Length and Distance Converter Mass Converter Bulk and Food Volume Converter Area Converter Culinary Recipe Volume and Units Converter Temperature Converter Pressure, Stress, Young's Modulus Converter Energy and Work Converter Power Converter Force Converter Time Converter Linear Velocity Converter Flat Angle Converter Thermal Efficiency and Fuel Efficiency Numeric Conversion Systems Converter of Information Quantity Measurement Currency Rates Women's Clothing and Shoes Sizes Men's Clothing and Shoes Sizes Angular Velocity and Speed ​​Converter Acceleration Converter Angular Acceleration Converter Density Converter Specific Volume Converter Moment of Inertia Converter Moment of Force Converter Torque converter Specific calorific value (mass) converter Energy density and fuel calorific value (volume) converter Differential temperature converter Coefficient converter Thermal Expansion Curve Thermal Resistance Converter Thermal Conductivity Converter Specific Heat Capacity Converter Thermal Exposure and Radiation Power Converter Heat Flux Density Converter Heat Transfer Coefficient Converter Volumetric Flow Rate Converter Mass Flow Rate Converter Molar Flow Rate Converter Mass Flux Density Converter Molar Concentration Converter Mass Concentration in Solution Converter absolute) viscosity Kinematic viscosity converter Surface tension converter Vapor permeability converter Water vapor flux density converter Sound level converter Microphone sensitivity converter Sound pressure level (SPL) converter Sound pressure level converter with selectable reference pressure Luminance converter Luminous intensity converter Illumination converter Computer graphics resolution converter Frequency and Wavelength Converter Optical Power in Diopters and Focal distance Diopter power and lens magnification (×) Electric charge converter Linear charge density converter Surface charge density converter Bulk charge density converter Electric current linear current density converter Surface current density converter Electric field strength converter Electrostatic potential and voltage converter Electrostatic potential and voltage converter Electrical resistance converter Converter electrical resistivity Electrical conductivity converter Electrical conductivity converter Electrical capacitance Inductance converter American wire gauge converter Levels in dBm (dBm or dBmW), dBV (dBV), watts, etc. units Magnetomotive force converter Magnetic field strength converter Magnetic flux converter Magnetic induction converter Radiation. Ionizing Radiation Absorbed Dose Rate Converter Radioactivity. Radioactive Decay Radiation Converter. Exposure Dose Converter Radiation. Absorbed Dose Converter Decimal Prefix Converter Data Transfer Typography and Image Processing Unit Converter Timber Volume Unit Converter Calculating Molar Mass Periodic Table of Chemical Elements D. I. Mendeleev

1 gigahertz [GHz] = 1,000,000,000 hertz [Hz]

Initial value

Converted value

hertz exahertz petahertz terahertz gigahertz megahertz kilohertz hectohertz decahertz decigertz santigertz millihertz microhertz nanohertz picohertz femtohertz attohertz cycles per second wavelength in exameters wavelength in petameters wavelength in terameters wavelength in megameters wavelength in kilometers in decameters wavelength in meters wavelength in decimeters wavelength in centimeters wavelength in millimeters wavelength in micrometers Compton wavelength of an electron Compton wavelength of a proton Compton wavelength of a neutron revolutions per second revolutions per minute revolutions per hour revolutions per day

Sound pressure level

More about frequency and wavelength

General information

Frequency

Frequency is a quantity that measures how often a particular periodic process repeats. In physics, frequency is used to describe the properties of wave processes. Wave frequency - the number of complete cycles of the wave process per unit of time. The SI unit of frequency is hertz (Hz). One hertz is equal to one oscillation per second.

Wavelength

There are many different types of waves in nature, from wind-induced sea waves to electromagnetic waves. The properties of electromagnetic waves depend on the wavelength. Such waves are divided into several types:

• Gamma rays with a wavelength of up to 0.01 nanometer (nm).
• X-rays with a wavelength of 0.01 nm to 10 nm.
• Waves ultraviolet which have a length of 10 to 380 nm. They are not visible to the human eye.
• Light in visible part of the spectrum with a wavelength of 380-700 nm.
• Invisible to humans infrared radiation with a wavelength from 700 nm to 1 millimeter.
• Infrared waves are followed by microwave, with a wavelength from 1 millimeter to 1 meter.
• The longest - radio waves... Their length starts from 1 meter.

This article is about electromagnetic radiation, and especially light. In it, we will discuss how wavelength and frequency affect light, including the visible spectrum, ultraviolet and infrared radiation.

Electromagnetic radiation

Electromagnetic radiation is energy, the properties of which are simultaneously similar to those of waves and particles. This feature is called wave-particle duality. Electromagnetic waves consist of a magnetic wave and an electrical wave perpendicular to it.

The energy of electromagnetic radiation is the result of the movement of particles called photons. The higher the frequency of radiation, the more active they are, and the more harm they can bring to the cells and tissues of living organisms. This is because the higher the frequency of the radiation, the more energy they carry. Great energy allows them to change the molecular structure of the substances on which they act. That is why ultraviolet, X-ray and gamma radiation are so harmful to animals and plants. A huge part of this radiation is in space. It is also present on Earth, despite the fact that the ozone layer of the atmosphere around the Earth blocks most of it.

Electromagnetic radiation and atmosphere

The earth's atmosphere only transmits electromagnetic radiation at a specific frequency. Most of gamma rays, X-rays, ultraviolet light, some infrared radiation, and long radio waves are blocked by the Earth's atmosphere. The atmosphere absorbs them and does not let them go further. Part of the electromagnetic waves, in particular, radiation in the short-wave range, is reflected from the ionosphere. All other radiation hits the surface of the Earth. In the upper atmospheric layers, that is, farther from the surface of the Earth, there is more radiation than in the lower layers. Therefore, the higher, the more dangerous it is for living organisms to be there without protective suits.

The atmosphere transmits a small amount of ultraviolet light to the Earth and is harmful to the skin. It is because of ultraviolet rays that people get sunburn and can even get skin cancer. On the other hand, some rays transmitted by the atmosphere are beneficial. For example, infrared rays that hit the Earth's surface are used in astronomy - infrared telescopes track infrared rays emitted by astronomical objects. The higher from the surface of the Earth, the more infrared radiation, therefore telescopes are often installed on mountain tops and other elevations. Sometimes they are sent into space to improve the visibility of infrared rays.

Relationship between frequency and wavelength

Frequency and wavelength are inversely proportional to each other. This means that as the wavelength increases, the frequency decreases and vice versa. It is easy to imagine: if the frequency of oscillations of the wave process is high, then the time between oscillations is much shorter than for waves, the oscillation frequency of which is less. If you imagine a wave on a chart, then the distance between its peaks will be the smaller, the more oscillations it makes over a certain period of time.

To determine the speed of propagation of a wave in a medium, it is necessary to multiply the frequency of the wave by its length. Electromagnetic waves in a vacuum always propagate at the same speed. This speed is known as the speed of light. It is equal to 299 & nbsp792 & nbsp458 meters per second.

Light

Visible light is electromagnetic waves of frequency and length that determine its color.

Wavelength and color

The shortest wavelength of visible light is 380 nanometers. It is purple, followed by blue and cyan, then green, yellow, orange, and finally red. White light consists of all colors at once, that is, white objects reflect all colors. This can be seen with a prism. The light entering it is refracted and lined up in a strip of colors in the same sequence as in a rainbow. This sequence is from the colors with the shortest wavelength to the longest. The dependence of the speed of propagation of light in matter on the wavelength is called dispersion.

A rainbow is formed in a similar way. Water droplets scattered in the atmosphere after rain behave like a prism and refract every wave. The colors of the rainbow are so important that in many languages ​​there are mnemonics, that is, a technique for memorizing the colors of the rainbow, so simple that even children can remember them. Many Russian speaking children know that "Every hunter wants to know where the pheasant is sitting." Some people come up with their own mnemonics, and this is a particularly useful exercise for children, because when they come up with their own method of remembering the colors of the rainbow, they will remember them faster.

The light to which the human eye is most sensitive is green, with a wavelength of 555 nm in light environments and 505 nm in twilight and darkness. Not all animals can distinguish colors. In cats, for example, color vision is not developed. On the other hand, some animals see colors much better than humans. For example, some species see ultraviolet and infrared light.

Light reflection

The color of an object is determined by the wavelength of light reflected from its surface. White objects reflect all waves of the visible spectrum, while black objects, on the contrary, absorb all waves and reflect nothing.

One of the natural materials with a high dispersion coefficient is diamond. Properly cut diamonds reflect light from both the outer and inner edges, refracting it, just like a prism. In this case, it is important that most of this light is reflected upward towards the eye, and not, for example, downward, into the frame, where it is not visible. Thanks to their high dispersion, diamonds shine very beautifully in the sun and under artificial light. Glass cut like a diamond also shines, but not as much. This is because, due to their chemical composition, diamonds reflect light much better than glass. The angles used when cutting diamonds are extremely important because corners that are too sharp or too obtuse either prevent light from reflecting off the interior walls or reflect light into the setting, as shown in the illustration.

Spectroscopy

Spectral analysis or spectroscopy is sometimes used to determine the chemical composition of a substance. This method is especially good if the chemical analysis of a substance cannot be carried out by working with it directly, for example, when determining the chemical composition of stars. Knowing what kind of electromagnetic radiation a body absorbs, you can determine what it consists of. Absorption spectroscopy, one of the branches of spectroscopy, determines which radiation is absorbed by the body. Such analysis can be done at a distance, therefore it is often used in astronomy, as well as in working with poisonous and dangerous substances.

Determination of the presence of electromagnetic radiation

Visible light, like all electromagnetic radiation, is energy. The more energy is emitted, the easier it is to measure this radiation. The amount of radiated energy decreases as the wavelength increases. Vision is possible precisely because humans and animals recognize this energy and sense the difference between radiation of different wavelengths. Electromagnetic radiation of different lengths is perceived by the eye as different colors. According to this principle, not only the eyes of animals and people work, but also technologies created by people for processing electromagnetic radiation.

Visible light

People and animals see a wide range of electromagnetic radiation. Most people and animals, for example, react to visible light and some animals are also exposed to ultraviolet and infrared rays. The ability to distinguish colors - not in all animals - some only see the difference between light and dark surfaces. Our brain determines the color as follows: photons of electromagnetic radiation enter the eye on the retina and, passing through it, excite the cones, photoreceptors of the eye. As a result, a signal is transmitted through the nervous system to the brain. In addition to cones, there are other photoreceptors, rods, in the eyes, but they are not able to distinguish colors. Their purpose is to determine the brightness and intensity of light.

There are usually several types of cones in the eye. There are three types in humans, each of which absorbs photons of light within specific wavelengths. When they are absorbed, a chemical reaction occurs, as a result of which nerve impulses with information about the wavelength enter the brain. These signals are processed by the visual cortex. This is the part of the brain responsible for the perception of sound. Each type of cone is responsible only for waves with a certain length, so to get a complete picture of the color, the information received from all the cones is added together.

Some animals have even more types of cones than humans. So, for example, in some species of fish and birds, there are from four to five types. Interestingly, some animal females have more types of cones than males. Some birds, such as seagulls that catch their prey in or on the water, have yellow or red oil droplets inside the cones that act as a filter. This helps them see more colors. The eyes of reptiles are arranged in a similar way.

Infrared light

In snakes, unlike humans, not only visual receptors, but also sensory organs that respond to infrared radiation... They absorb the energy of infrared rays, that is, they react to heat. Some devices, such as night vision goggles, also react to the heat generated by the infrared emitter. Such devices are used by the military, as well as to ensure the safety and security of premises and territory. Animals that see infrared light, and devices that can recognize it, see not only objects that are in their field of vision at the moment, but also traces of objects, animals, or people that were there before, if too a lot of time. For example, snakes can be seen if rodents have dug a hole in the ground, and police who use night vision devices can see if traces of a crime, such as money, drugs, or something else, have recently been hidden in the ground. Devices for recording infrared radiation are used in telescopes, as well as for checking containers and cameras for leaks. With their help, the place of heat leakage is clearly visible. In medicine, infrared images are used for diagnostics. In art history - to determine what is depicted under the top coat of paint. Night vision devices are used to guard premises.

Ultraviolet light

Some fish see ultraviolet light... Their eyes contain pigment that is sensitive to ultraviolet rays. Fish skin contains areas that reflect ultraviolet light that are invisible to humans and other animals - which is often used in the animal kingdom to mark the sex of animals, as well as for social purposes. Some birds also see ultraviolet light. This skill is especially important during the mating season when the birds are looking for potential mates. The surfaces of some plants also reflect ultraviolet light well, and the ability to see it helps in finding food. In addition to fish and birds, some reptiles, such as turtles, lizards, and green iguanas (pictured), see ultraviolet light.

The human eye, like the eyes of animals, absorbs ultraviolet light, but cannot process it. In humans, it destroys cells in the eye, especially in the cornea and lens. This, in turn, causes various diseases and even blindness. Despite the fact that ultraviolet light is harmful to vision, a small amount of it is necessary for humans and animals to produce vitamin D. Ultraviolet radiation, like infrared, is used in many industries, for example, in medicine for disinfection, in astronomy for observing stars and other objects. and in chemistry for the solidification of liquid substances, as well as for visualization, that is, to create diagrams of the distribution of substances in a certain space. With the help of ultraviolet light, counterfeit banknotes and passes are detected if signs are to be printed on them with special ink recognizable using ultraviolet light. In the case of counterfeiting documents, an ultraviolet lamp does not always help, as criminals sometimes use the real document and replace it with a photograph or other information, so that the markings for the UV lamps remain. There are many other uses for ultraviolet radiation as well.

Color blindness

Some people are unable to distinguish colors due to visual defects. This problem is called color blindness or color blindness, after the person who first described this feature of vision. Sometimes people can't see only colors at a certain wavelength, and sometimes they can't see colors at all. Often the cause is underdeveloped or damaged photoreceptors, but in some cases the problem lies in damage to the pathway of the nervous system, for example, in the visual cortex of the brain, where color information is processed. In many cases, this state creates inconveniences and problems for people and animals, but sometimes the inability to distinguish colors, on the contrary, is an advantage. This is confirmed by the fact that, despite the long years of evolution, color vision is not developed in many animals. People and animals that are color blind may, for example, see camouflage of other animals well.

Despite the benefits of color blindness, in society it is considered a problem, and for people with color blindness, the road to some professions is closed. Usually they cannot get full rights to fly the aircraft without restrictions. In many countries, driving licenses for these people also have restrictions, and in some cases they cannot get a license at all. Therefore, they cannot always find a job where they need to drive a car, an airplane, and other vehicles. They also find it difficult to find work where the ability to identify and use colors is of great importance. For example, they find it difficult to become designers, or work in an environment where color is used as a signal (for example, about danger).

Work is underway to create more favorable conditions for people with color blindness. For example, there are tables in which colors correspond to signs, and in some countries these signs are used in offices and public places along with color. Some designers do not use or limit the use of color to convey important information in their work. Instead of, or along with color, they use brightness, text, and other ways to highlight information so that even people who cannot distinguish colors can fully receive the information conveyed by the designer. In most cases, people with color blindness do not distinguish between red and green, so designers sometimes replace the combination “red = danger, green = okay” with red and blue. Most operating systems also allow you to customize colors so that people with color blindness can see everything.

Color in machine vision

Machine vision in color is a fast-growing branch of artificial intelligence. Until recently, most of the work in this area took place with monochrome images, but now more and more scientific laboratories are working with color. Some algorithms for working with monochrome images are also used for processing color images.

Application

Machine vision is used in a number of industries, such as controlling robots, self-driving cars, and unmanned aerial vehicles. It is useful in the field of security, for example, for identifying people and objects from photographs, for searching databases, for tracking the movement of objects, depending on their color, and so on. Determining the location of moving objects allows the computer to determine the direction of a person's gaze or track the movement of cars, people, hands, and other objects.

In order to correctly identify unfamiliar objects, it is important to know about their shape and other properties, but color information is not so important. When working with familiar objects, on the contrary, color helps to recognize them faster. Working with color is also convenient because color information can be obtained even from low-resolution images. Recognizing the shape of an object, as opposed to color, requires high resolution. Working with color instead of object shape can reduce image processing time and use less computer resources. Color helps to recognize objects of the same shape, and can also be used as a signal or sign (for example, red is a signal of danger). In this case, you do not need to recognize the shape of this sign, or the text written on it. There are many interesting examples of the use of color vision on the YouTube website.

Processing color information

Photos processed by the computer are either uploaded by users or taken by the built-in camera. The process of digital photography and video shooting is well mastered, but the processing of these images, especially in color, is associated with many difficulties, many of which have not yet been resolved. This is due to the fact that color vision in humans and animals is very complex, and it is not easy to create computer vision similar to human vision. Vision, like hearing, is based on adaptation to the environment. The perception of sound depends not only on the frequency, sound pressure and duration of the sound, but also on the presence or absence of other sounds in the environment. So it is with vision - the perception of color depends not only on frequency and wavelength, but also on the characteristics of the environment. For example, the colors of the surrounding objects affect our perception of color.

From an evolutionary perspective, such adaptations are necessary to help us get used to our environment and to stop paying attention to insignificant elements, but to direct our full attention to what is changing in the environment. This is necessary in order to make it easier to spot predators and find food. Sometimes optical illusions occur due to this adaptation. For example, depending on the color of the surrounding objects, we perceive the color of two bodies differently, even when they reflect light with the same wavelength. The illustration shows an example of such an optical illusion. The brown square at the top of the image (second row, second column) appears lighter than the brown square at the bottom of the image (fifth row, second column). In fact, their colors are the same. Even knowing this, we still perceive them as different colors. Since our perception of color is so complex, it is difficult for programmers to describe all these nuances in algorithms for machine vision. Despite these difficulties, we have already achieved a lot in this area.

Unit Converter articles were edited and illustrated by Anatoly Zolotkov

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Length and Distance Converter Mass Converter Bulk and Food Volume Converter Area Converter Culinary Recipe Volume and Units Converter Temperature Converter Pressure, Stress, Young's Modulus Converter Energy and Work Converter Power Converter Force Converter Time Converter Linear Velocity Converter Flat Angle Converter Thermal Efficiency and Fuel Efficiency Numeric Conversion Systems Converter of Information Quantity Measurement Currency Rates Women's Clothing and Shoes Sizes Men's Clothing and Shoes Sizes Angular Velocity and Speed ​​Converter Acceleration Converter Angular Acceleration Converter Density Converter Specific Volume Converter Moment of Inertia Converter Moment of Force Converter Torque converter Specific calorific value (mass) converter Energy density and fuel calorific value (volume) converter Differential temperature converter Coefficient converter Thermal Expansion Curve Thermal Resistance Converter Thermal Conductivity Converter Specific Heat Capacity Converter Thermal Exposure and Radiation Power Converter Heat Flux Density Converter Heat Transfer Coefficient Converter Volumetric Flow Rate Converter Mass Flow Rate Converter Molar Flow Rate Converter Mass Flux Density Converter Molar Concentration Converter Mass Concentration in Solution Converter absolute) viscosity Kinematic viscosity converter Surface tension converter Vapor permeability converter Water vapor flux density converter Sound level converter Microphone sensitivity converter Sound pressure level (SPL) converter Sound pressure level converter with selectable reference pressure Luminance converter Luminous intensity converter Illumination converter Computer graphics resolution converter Frequency and Wavelength Converter Optical Power in Diopters and Focal distance Diopter power and lens magnification (×) Electric charge converter Linear charge density converter Surface charge density converter Bulk charge density converter Electric current linear current density converter Surface current density converter Electric field strength converter Electrostatic potential and voltage converter Electrostatic potential and voltage converter Electrical resistance converter Converter electrical resistivity Electrical conductivity converter Electrical conductivity converter Electrical capacitance Inductance converter American wire gauge converter Levels in dBm (dBm or dBmW), dBV (dBV), watts, etc. units Magnetomotive force converter Magnetic field strength converter Magnetic flux converter Magnetic induction converter Radiation. Ionizing Radiation Absorbed Dose Rate Converter Radioactivity. Radioactive Decay Radiation Converter. Exposure Dose Converter Radiation. Absorbed Dose Converter Decimal Prefix Converter Data Transfer Typography and Image Processing Unit Converter Timber Volume Unit Converter Calculating Molar Mass Periodic Table of Chemical Elements D. I. Mendeleev

1 megahertz [MHz] = 1,000,000 hertz [Hz]

Initial value

Converted value

hertz exahertz petahertz terahertz gigahertz megahertz kilohertz hectohertz decahertz decigertz santigertz millihertz microhertz nanohertz picohertz femtohertz attohertz cycles per second wavelength in exameters wavelength in petameters wavelength in terameters wavelength in megameters wavelength in kilometers in decameters wavelength in meters wavelength in decimeters wavelength in centimeters wavelength in millimeters wavelength in micrometers Compton wavelength of an electron Compton wavelength of a proton Compton wavelength of a neutron revolutions per second revolutions per minute revolutions per hour revolutions per day

American wire gauge

More about frequency and wavelength

General information

Frequency

Frequency is a quantity that measures how often a particular periodic process repeats. In physics, frequency is used to describe the properties of wave processes. Wave frequency - the number of complete cycles of the wave process per unit of time. The SI unit of frequency is hertz (Hz). One hertz is equal to one oscillation per second.

Wavelength

There are many different types of waves in nature, from wind-induced sea waves to electromagnetic waves. The properties of electromagnetic waves depend on the wavelength. Such waves are divided into several types:

• Gamma rays with a wavelength of up to 0.01 nanometer (nm).
• X-rays with a wavelength of 0.01 nm to 10 nm.
• Waves ultraviolet which have a length of 10 to 380 nm. They are not visible to the human eye.
• Light in visible part of the spectrum with a wavelength of 380-700 nm.
• Invisible to humans infrared radiation with a wavelength from 700 nm to 1 millimeter.
• Infrared waves are followed by microwave, with a wavelength from 1 millimeter to 1 meter.
• The longest - radio waves... Their length starts from 1 meter.

This article is about electromagnetic radiation, and especially light. In it, we will discuss how wavelength and frequency affect light, including the visible spectrum, ultraviolet and infrared radiation.

Electromagnetic radiation

Electromagnetic radiation is energy, the properties of which are simultaneously similar to those of waves and particles. This feature is called wave-particle duality. Electromagnetic waves consist of a magnetic wave and an electrical wave perpendicular to it.

The energy of electromagnetic radiation is the result of the movement of particles called photons. The higher the frequency of radiation, the more active they are, and the more harm they can bring to the cells and tissues of living organisms. This is because the higher the frequency of the radiation, the more energy they carry. Great energy allows them to change the molecular structure of the substances on which they act. That is why ultraviolet, X-ray and gamma radiation are so harmful to animals and plants. A huge part of this radiation is in space. It is also present on Earth, despite the fact that the ozone layer of the atmosphere around the Earth blocks most of it.

Electromagnetic radiation and atmosphere

The earth's atmosphere only transmits electromagnetic radiation at a specific frequency. Most of gamma rays, X-rays, ultraviolet light, some infrared radiation, and long radio waves are blocked by the Earth's atmosphere. The atmosphere absorbs them and does not let them go further. Part of the electromagnetic waves, in particular, radiation in the short-wave range, is reflected from the ionosphere. All other radiation hits the surface of the Earth. In the upper atmospheric layers, that is, farther from the surface of the Earth, there is more radiation than in the lower layers. Therefore, the higher, the more dangerous it is for living organisms to be there without protective suits.

The atmosphere transmits a small amount of ultraviolet light to the Earth and is harmful to the skin. It is because of ultraviolet rays that people get sunburn and can even get skin cancer. On the other hand, some rays transmitted by the atmosphere are beneficial. For example, infrared rays that hit the Earth's surface are used in astronomy - infrared telescopes track infrared rays emitted by astronomical objects. The higher from the surface of the Earth, the more infrared radiation, therefore telescopes are often installed on mountain tops and other elevations. Sometimes they are sent into space to improve the visibility of infrared rays.

Relationship between frequency and wavelength

Frequency and wavelength are inversely proportional to each other. This means that as the wavelength increases, the frequency decreases and vice versa. It is easy to imagine: if the frequency of oscillations of the wave process is high, then the time between oscillations is much shorter than for waves, the oscillation frequency of which is less. If you imagine a wave on a chart, then the distance between its peaks will be the smaller, the more oscillations it makes over a certain period of time.

To determine the speed of propagation of a wave in a medium, it is necessary to multiply the frequency of the wave by its length. Electromagnetic waves in a vacuum always propagate at the same speed. This speed is known as the speed of light. It is equal to 299 & nbsp792 & nbsp458 meters per second.

Light

Visible light is electromagnetic waves of frequency and length that determine its color.

Wavelength and color

The shortest wavelength of visible light is 380 nanometers. It is purple, followed by blue and cyan, then green, yellow, orange, and finally red. White light consists of all colors at once, that is, white objects reflect all colors. This can be seen with a prism. The light entering it is refracted and lined up in a strip of colors in the same sequence as in a rainbow. This sequence is from the colors with the shortest wavelength to the longest. The dependence of the speed of propagation of light in matter on the wavelength is called dispersion.

A rainbow is formed in a similar way. Water droplets scattered in the atmosphere after rain behave like a prism and refract every wave. The colors of the rainbow are so important that in many languages ​​there are mnemonics, that is, a technique for memorizing the colors of the rainbow, so simple that even children can remember them. Many Russian speaking children know that "Every hunter wants to know where the pheasant is sitting." Some people come up with their own mnemonics, and this is a particularly useful exercise for children, because when they come up with their own method of remembering the colors of the rainbow, they will remember them faster.

The light to which the human eye is most sensitive is green, with a wavelength of 555 nm in light environments and 505 nm in twilight and darkness. Not all animals can distinguish colors. In cats, for example, color vision is not developed. On the other hand, some animals see colors much better than humans. For example, some species see ultraviolet and infrared light.

Light reflection

The color of an object is determined by the wavelength of light reflected from its surface. White objects reflect all waves of the visible spectrum, while black objects, on the contrary, absorb all waves and reflect nothing.

One of the natural materials with a high dispersion coefficient is diamond. Properly cut diamonds reflect light from both the outer and inner edges, refracting it, just like a prism. In this case, it is important that most of this light is reflected upward towards the eye, and not, for example, downward, into the frame, where it is not visible. Thanks to their high dispersion, diamonds shine very beautifully in the sun and under artificial light. Glass cut like a diamond also shines, but not as much. This is because, due to their chemical composition, diamonds reflect light much better than glass. The angles used when cutting diamonds are extremely important because corners that are too sharp or too obtuse either prevent light from reflecting off the interior walls or reflect light into the setting, as shown in the illustration.

Spectroscopy

Spectral analysis or spectroscopy is sometimes used to determine the chemical composition of a substance. This method is especially good if the chemical analysis of a substance cannot be carried out by working with it directly, for example, when determining the chemical composition of stars. Knowing what kind of electromagnetic radiation a body absorbs, you can determine what it consists of. Absorption spectroscopy, one of the branches of spectroscopy, determines which radiation is absorbed by the body. Such analysis can be done at a distance, therefore it is often used in astronomy, as well as in working with poisonous and dangerous substances.

Determination of the presence of electromagnetic radiation

Visible light, like all electromagnetic radiation, is energy. The more energy is emitted, the easier it is to measure this radiation. The amount of radiated energy decreases as the wavelength increases. Vision is possible precisely because humans and animals recognize this energy and sense the difference between radiation of different wavelengths. Electromagnetic radiation of different lengths is perceived by the eye as different colors. According to this principle, not only the eyes of animals and people work, but also technologies created by people for processing electromagnetic radiation.

Visible light

People and animals see a wide range of electromagnetic radiation. Most people and animals, for example, react to visible light and some animals are also exposed to ultraviolet and infrared rays. The ability to distinguish colors - not in all animals - some only see the difference between light and dark surfaces. Our brain determines the color as follows: photons of electromagnetic radiation enter the eye on the retina and, passing through it, excite the cones, photoreceptors of the eye. As a result, a signal is transmitted through the nervous system to the brain. In addition to cones, there are other photoreceptors, rods, in the eyes, but they are not able to distinguish colors. Their purpose is to determine the brightness and intensity of light.

There are usually several types of cones in the eye. There are three types in humans, each of which absorbs photons of light within specific wavelengths. When they are absorbed, a chemical reaction occurs, as a result of which nerve impulses with information about the wavelength enter the brain. These signals are processed by the visual cortex. This is the part of the brain responsible for the perception of sound. Each type of cone is responsible only for waves with a certain length, so to get a complete picture of the color, the information received from all the cones is added together.

Some animals have even more types of cones than humans. So, for example, in some species of fish and birds, there are from four to five types. Interestingly, some animal females have more types of cones than males. Some birds, such as seagulls that catch their prey in or on the water, have yellow or red oil droplets inside the cones that act as a filter. This helps them see more colors. The eyes of reptiles are arranged in a similar way.

Infrared light

In snakes, unlike humans, not only visual receptors, but also sensory organs that respond to infrared radiation... They absorb the energy of infrared rays, that is, they react to heat. Some devices, such as night vision goggles, also react to the heat generated by the infrared emitter. Such devices are used by the military, as well as to ensure the safety and security of premises and territory. Animals that see infrared light, and devices that can recognize it, see not only objects that are in their field of vision at the moment, but also traces of objects, animals, or people that were there before, if too a lot of time. For example, snakes can be seen if rodents have dug a hole in the ground, and police who use night vision devices can see if traces of a crime, such as money, drugs, or something else, have recently been hidden in the ground. Devices for recording infrared radiation are used in telescopes, as well as for checking containers and cameras for leaks. With their help, the place of heat leakage is clearly visible. In medicine, infrared images are used for diagnostics. In art history - to determine what is depicted under the top coat of paint. Night vision devices are used to guard premises.

Ultraviolet light

Some fish see ultraviolet light... Their eyes contain pigment that is sensitive to ultraviolet rays. Fish skin contains areas that reflect ultraviolet light that are invisible to humans and other animals - which is often used in the animal kingdom to mark the sex of animals, as well as for social purposes. Some birds also see ultraviolet light. This skill is especially important during the mating season when the birds are looking for potential mates. The surfaces of some plants also reflect ultraviolet light well, and the ability to see it helps in finding food. In addition to fish and birds, some reptiles, such as turtles, lizards, and green iguanas (pictured), see ultraviolet light.

The human eye, like the eyes of animals, absorbs ultraviolet light, but cannot process it. In humans, it destroys cells in the eye, especially in the cornea and lens. This, in turn, causes various diseases and even blindness. Despite the fact that ultraviolet light is harmful to vision, a small amount of it is necessary for humans and animals to produce vitamin D. Ultraviolet radiation, like infrared, is used in many industries, for example, in medicine for disinfection, in astronomy for observing stars and other objects. and in chemistry for the solidification of liquid substances, as well as for visualization, that is, to create diagrams of the distribution of substances in a certain space. With the help of ultraviolet light, counterfeit banknotes and passes are detected if signs are to be printed on them with special ink recognizable using ultraviolet light. In the case of counterfeiting documents, an ultraviolet lamp does not always help, as criminals sometimes use the real document and replace it with a photograph or other information, so that the markings for the UV lamps remain. There are many other uses for ultraviolet radiation as well.

Color blindness

Some people are unable to distinguish colors due to visual defects. This problem is called color blindness or color blindness, after the person who first described this feature of vision. Sometimes people can't see only colors at a certain wavelength, and sometimes they can't see colors at all. Often the cause is underdeveloped or damaged photoreceptors, but in some cases the problem lies in damage to the pathway of the nervous system, for example, in the visual cortex of the brain, where color information is processed. In many cases, this state creates inconveniences and problems for people and animals, but sometimes the inability to distinguish colors, on the contrary, is an advantage. This is confirmed by the fact that, despite the long years of evolution, color vision is not developed in many animals. People and animals that are color blind may, for example, see camouflage of other animals well.

Despite the benefits of color blindness, in society it is considered a problem, and for people with color blindness, the road to some professions is closed. Usually they cannot get full rights to fly the aircraft without restrictions. In many countries, driving licenses for these people also have restrictions, and in some cases they cannot get a license at all. Therefore, they cannot always find a job where they need to drive a car, an airplane, and other vehicles. They also find it difficult to find work where the ability to identify and use colors is of great importance. For example, they find it difficult to become designers, or work in an environment where color is used as a signal (for example, about danger).

Work is underway to create more favorable conditions for people with color blindness. For example, there are tables in which colors correspond to signs, and in some countries these signs are used in offices and public places along with color. Some designers do not use or limit the use of color to convey important information in their work. Instead of, or along with color, they use brightness, text, and other ways to highlight information so that even people who cannot distinguish colors can fully receive the information conveyed by the designer. In most cases, people with color blindness do not distinguish between red and green, so designers sometimes replace the combination “red = danger, green = okay” with red and blue. Most operating systems also allow you to customize colors so that people with color blindness can see everything.

Color in machine vision

Machine vision in color is a fast-growing branch of artificial intelligence. Until recently, most of the work in this area took place with monochrome images, but now more and more scientific laboratories are working with color. Some algorithms for working with monochrome images are also used for processing color images.

Application

Machine vision is used in a number of industries, such as controlling robots, self-driving cars, and unmanned aerial vehicles. It is useful in the field of security, for example, for identifying people and objects from photographs, for searching databases, for tracking the movement of objects, depending on their color, and so on. Determining the location of moving objects allows the computer to determine the direction of a person's gaze or track the movement of cars, people, hands, and other objects.

In order to correctly identify unfamiliar objects, it is important to know about their shape and other properties, but color information is not so important. When working with familiar objects, on the contrary, color helps to recognize them faster. Working with color is also convenient because color information can be obtained even from low-resolution images. Recognizing the shape of an object, as opposed to color, requires high resolution. Working with color instead of object shape can reduce image processing time and use less computer resources. Color helps to recognize objects of the same shape, and can also be used as a signal or sign (for example, red is a signal of danger). In this case, you do not need to recognize the shape of this sign, or the text written on it. There are many interesting examples of the use of color vision on the YouTube website.

Processing color information

Photos processed by the computer are either uploaded by users or taken by the built-in camera. The process of digital photography and video shooting is well mastered, but the processing of these images, especially in color, is associated with many difficulties, many of which have not yet been resolved. This is due to the fact that color vision in humans and animals is very complex, and it is not easy to create computer vision similar to human vision. Vision, like hearing, is based on adaptation to the environment. The perception of sound depends not only on the frequency, sound pressure and duration of the sound, but also on the presence or absence of other sounds in the environment. So it is with vision - the perception of color depends not only on frequency and wavelength, but also on the characteristics of the environment. For example, the colors of the surrounding objects affect our perception of color.

From an evolutionary perspective, such adaptations are necessary to help us get used to our environment and to stop paying attention to insignificant elements, but to direct our full attention to what is changing in the environment. This is necessary in order to make it easier to spot predators and find food. Sometimes optical illusions occur due to this adaptation. For example, depending on the color of the surrounding objects, we perceive the color of two bodies differently, even when they reflect light with the same wavelength. The illustration shows an example of such an optical illusion. The brown square at the top of the image (second row, second column) appears lighter than the brown square at the bottom of the image (fifth row, second column). In fact, their colors are the same. Even knowing this, we still perceive them as different colors. Since our perception of color is so complex, it is difficult for programmers to describe all these nuances in algorithms for machine vision. Despite these difficulties, we have already achieved a lot in this area.

Unit Converter articles were edited and illustrated by Anatoly Zolotkov

Do you find it difficult to translate a unit of measurement from one language to another? Colleagues are ready to help you. Post a question to TCTerms and you will receive an answer within a few minutes.

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1 hertz [Hz] = 1 cycles per second [cycles / s]

Initial value

Converted value

hertz exahertz petahertz terahertz gigahertz megahertz kilohertz hectohertz decahertz decigertz santigertz millihertz microhertz nanohertz picohertz femtohertz attohertz cycles per second wavelength in exameters wavelength in petameters wavelength in terameters wavelength in megameters wavelength in kilometers in decameters wavelength in meters wavelength in decimeters wavelength in centimeters wavelength in millimeters wavelength in micrometers Compton wavelength of an electron Compton wavelength of a proton Compton wavelength of a neutron revolutions per second revolutions per minute revolutions per hour revolutions per day

The science of making coffee: pressure

More about frequency and wavelength

General information

Frequency

Frequency is a quantity that measures how often a particular periodic process repeats. In physics, frequency is used to describe the properties of wave processes. Wave frequency - the number of complete cycles of the wave process per unit of time. The SI unit of frequency is hertz (Hz). One hertz is equal to one oscillation per second.

Wavelength

There are many different types of waves in nature, from wind-induced sea waves to electromagnetic waves. The properties of electromagnetic waves depend on the wavelength. Such waves are divided into several types:

• Gamma rays with a wavelength of up to 0.01 nanometer (nm).
• X-rays with a wavelength of 0.01 nm to 10 nm.
• Waves ultraviolet which have a length of 10 to 380 nm. They are not visible to the human eye.
• Light in visible part of the spectrum with a wavelength of 380-700 nm.
• Invisible to humans infrared radiation with a wavelength from 700 nm to 1 millimeter.
• Infrared waves are followed by microwave, with a wavelength from 1 millimeter to 1 meter.
• The longest - radio waves... Their length starts from 1 meter.

This article is about electromagnetic radiation, and especially light. In it, we will discuss how wavelength and frequency affect light, including the visible spectrum, ultraviolet and infrared radiation.

Electromagnetic radiation

Electromagnetic radiation is energy, the properties of which are simultaneously similar to those of waves and particles. This feature is called wave-particle duality. Electromagnetic waves consist of a magnetic wave and an electrical wave perpendicular to it.

The energy of electromagnetic radiation is the result of the movement of particles called photons. The higher the frequency of radiation, the more active they are, and the more harm they can bring to the cells and tissues of living organisms. This is because the higher the frequency of the radiation, the more energy they carry. Great energy allows them to change the molecular structure of the substances on which they act. That is why ultraviolet, X-ray and gamma radiation are so harmful to animals and plants. A huge part of this radiation is in space. It is also present on Earth, despite the fact that the ozone layer of the atmosphere around the Earth blocks most of it.

Electromagnetic radiation and atmosphere

The earth's atmosphere only transmits electromagnetic radiation at a specific frequency. Most of gamma rays, X-rays, ultraviolet light, some infrared radiation, and long radio waves are blocked by the Earth's atmosphere. The atmosphere absorbs them and does not let them go further. Part of the electromagnetic waves, in particular, radiation in the short-wave range, is reflected from the ionosphere. All other radiation hits the surface of the Earth. In the upper atmospheric layers, that is, farther from the surface of the Earth, there is more radiation than in the lower layers. Therefore, the higher, the more dangerous it is for living organisms to be there without protective suits.

The atmosphere transmits a small amount of ultraviolet light to the Earth and is harmful to the skin. It is because of ultraviolet rays that people get sunburn and can even get skin cancer. On the other hand, some rays transmitted by the atmosphere are beneficial. For example, infrared rays that hit the Earth's surface are used in astronomy - infrared telescopes track infrared rays emitted by astronomical objects. The higher from the surface of the Earth, the more infrared radiation, therefore telescopes are often installed on mountain tops and other elevations. Sometimes they are sent into space to improve the visibility of infrared rays.

Relationship between frequency and wavelength

Frequency and wavelength are inversely proportional to each other. This means that as the wavelength increases, the frequency decreases and vice versa. It is easy to imagine: if the frequency of oscillations of the wave process is high, then the time between oscillations is much shorter than for waves, the oscillation frequency of which is less. If you imagine a wave on a chart, then the distance between its peaks will be the smaller, the more oscillations it makes over a certain period of time.

To determine the speed of propagation of a wave in a medium, it is necessary to multiply the frequency of the wave by its length. Electromagnetic waves in a vacuum always propagate at the same speed. This speed is known as the speed of light. It is equal to 299 & nbsp792 & nbsp458 meters per second.

Light

Visible light is electromagnetic waves of frequency and length that determine its color.

Wavelength and color

The shortest wavelength of visible light is 380 nanometers. It is purple, followed by blue and cyan, then green, yellow, orange, and finally red. White light consists of all colors at once, that is, white objects reflect all colors. This can be seen with a prism. The light entering it is refracted and lined up in a strip of colors in the same sequence as in a rainbow. This sequence is from the colors with the shortest wavelength to the longest. The dependence of the speed of propagation of light in matter on the wavelength is called dispersion.

A rainbow is formed in a similar way. Water droplets scattered in the atmosphere after rain behave like a prism and refract every wave. The colors of the rainbow are so important that in many languages ​​there are mnemonics, that is, a technique for memorizing the colors of the rainbow, so simple that even children can remember them. Many Russian speaking children know that "Every hunter wants to know where the pheasant is sitting." Some people come up with their own mnemonics, and this is a particularly useful exercise for children, because when they come up with their own method of remembering the colors of the rainbow, they will remember them faster.

The light to which the human eye is most sensitive is green, with a wavelength of 555 nm in light environments and 505 nm in twilight and darkness. Not all animals can distinguish colors. In cats, for example, color vision is not developed. On the other hand, some animals see colors much better than humans. For example, some species see ultraviolet and infrared light.

Light reflection

The color of an object is determined by the wavelength of light reflected from its surface. White objects reflect all waves of the visible spectrum, while black objects, on the contrary, absorb all waves and reflect nothing.

One of the natural materials with a high dispersion coefficient is diamond. Properly cut diamonds reflect light from both the outer and inner edges, refracting it, just like a prism. In this case, it is important that most of this light is reflected upward towards the eye, and not, for example, downward, into the frame, where it is not visible. Thanks to their high dispersion, diamonds shine very beautifully in the sun and under artificial light. Glass cut like a diamond also shines, but not as much. This is because, due to their chemical composition, diamonds reflect light much better than glass. The angles used when cutting diamonds are extremely important because corners that are too sharp or too obtuse either prevent light from reflecting off the interior walls or reflect light into the setting, as shown in the illustration.

Spectroscopy

Spectral analysis or spectroscopy is sometimes used to determine the chemical composition of a substance. This method is especially good if the chemical analysis of a substance cannot be carried out by working with it directly, for example, when determining the chemical composition of stars. Knowing what kind of electromagnetic radiation a body absorbs, you can determine what it consists of. Absorption spectroscopy, one of the branches of spectroscopy, determines which radiation is absorbed by the body. Such analysis can be done at a distance, therefore it is often used in astronomy, as well as in working with poisonous and dangerous substances.

Determination of the presence of electromagnetic radiation

Visible light, like all electromagnetic radiation, is energy. The more energy is emitted, the easier it is to measure this radiation. The amount of radiated energy decreases as the wavelength increases. Vision is possible precisely because humans and animals recognize this energy and sense the difference between radiation of different wavelengths. Electromagnetic radiation of different lengths is perceived by the eye as different colors. According to this principle, not only the eyes of animals and people work, but also technologies created by people for processing electromagnetic radiation.

Visible light

People and animals see a wide range of electromagnetic radiation. Most people and animals, for example, react to visible light and some animals are also exposed to ultraviolet and infrared rays. The ability to distinguish colors - not in all animals - some only see the difference between light and dark surfaces. Our brain determines the color as follows: photons of electromagnetic radiation enter the eye on the retina and, passing through it, excite the cones, photoreceptors of the eye. As a result, a signal is transmitted through the nervous system to the brain. In addition to cones, there are other photoreceptors, rods, in the eyes, but they are not able to distinguish colors. Their purpose is to determine the brightness and intensity of light.

There are usually several types of cones in the eye. There are three types in humans, each of which absorbs photons of light within specific wavelengths. When they are absorbed, a chemical reaction occurs, as a result of which nerve impulses with information about the wavelength enter the brain. These signals are processed by the visual cortex. This is the part of the brain responsible for the perception of sound. Each type of cone is responsible only for waves with a certain length, so to get a complete picture of the color, the information received from all the cones is added together.

Some animals have even more types of cones than humans. So, for example, in some species of fish and birds, there are from four to five types. Interestingly, some animal females have more types of cones than males. Some birds, such as seagulls that catch their prey in or on the water, have yellow or red oil droplets inside the cones that act as a filter. This helps them see more colors. The eyes of reptiles are arranged in a similar way.

Infrared light

In snakes, unlike humans, not only visual receptors, but also sensory organs that respond to infrared radiation... They absorb the energy of infrared rays, that is, they react to heat. Some devices, such as night vision goggles, also react to the heat generated by the infrared emitter. Such devices are used by the military, as well as to ensure the safety and security of premises and territory. Animals that see infrared light, and devices that can recognize it, see not only objects that are in their field of vision at the moment, but also traces of objects, animals, or people that were there before, if too a lot of time. For example, snakes can be seen if rodents have dug a hole in the ground, and police who use night vision devices can see if traces of a crime, such as money, drugs, or something else, have recently been hidden in the ground. Devices for recording infrared radiation are used in telescopes, as well as for checking containers and cameras for leaks. With their help, the place of heat leakage is clearly visible. In medicine, infrared images are used for diagnostics. In art history - to determine what is depicted under the top coat of paint. Night vision devices are used to guard premises.

Ultraviolet light

Some fish see ultraviolet light... Their eyes contain pigment that is sensitive to ultraviolet rays. Fish skin contains areas that reflect ultraviolet light that are invisible to humans and other animals - which is often used in the animal kingdom to mark the sex of animals, as well as for social purposes. Some birds also see ultraviolet light. This skill is especially important during the mating season when the birds are looking for potential mates. The surfaces of some plants also reflect ultraviolet light well, and the ability to see it helps in finding food. In addition to fish and birds, some reptiles, such as turtles, lizards, and green iguanas (pictured), see ultraviolet light.

The human eye, like the eyes of animals, absorbs ultraviolet light, but cannot process it. In humans, it destroys cells in the eye, especially in the cornea and lens. This, in turn, causes various diseases and even blindness. Despite the fact that ultraviolet light is harmful to vision, a small amount of it is necessary for humans and animals to produce vitamin D. Ultraviolet radiation, like infrared, is used in many industries, for example, in medicine for disinfection, in astronomy for observing stars and other objects. and in chemistry for the solidification of liquid substances, as well as for visualization, that is, to create diagrams of the distribution of substances in a certain space. With the help of ultraviolet light, counterfeit banknotes and passes are detected if signs are to be printed on them with special ink recognizable using ultraviolet light. In the case of counterfeiting documents, an ultraviolet lamp does not always help, as criminals sometimes use the real document and replace it with a photograph or other information, so that the markings for the UV lamps remain. There are many other uses for ultraviolet radiation as well.

Color blindness

Some people are unable to distinguish colors due to visual defects. This problem is called color blindness or color blindness, after the person who first described this feature of vision. Sometimes people can't see only colors at a certain wavelength, and sometimes they can't see colors at all. Often the cause is underdeveloped or damaged photoreceptors, but in some cases the problem lies in damage to the pathway of the nervous system, for example, in the visual cortex of the brain, where color information is processed. In many cases, this state creates inconveniences and problems for people and animals, but sometimes the inability to distinguish colors, on the contrary, is an advantage. This is confirmed by the fact that, despite the long years of evolution, color vision is not developed in many animals. People and animals that are color blind may, for example, see camouflage of other animals well.

Despite the benefits of color blindness, in society it is considered a problem, and for people with color blindness, the road to some professions is closed. Usually they cannot get full rights to fly the aircraft without restrictions. In many countries, driving licenses for these people also have restrictions, and in some cases they cannot get a license at all. Therefore, they cannot always find a job where they need to drive a car, an airplane, and other vehicles. They also find it difficult to find work where the ability to identify and use colors is of great importance. For example, they find it difficult to become designers, or work in an environment where color is used as a signal (for example, about danger).

Work is underway to create more favorable conditions for people with color blindness. For example, there are tables in which colors correspond to signs, and in some countries these signs are used in offices and public places along with color. Some designers do not use or limit the use of color to convey important information in their work. Instead of, or along with color, they use brightness, text, and other ways to highlight information so that even people who cannot distinguish colors can fully receive the information conveyed by the designer. In most cases, people with color blindness do not distinguish between red and green, so designers sometimes replace the combination “red = danger, green = okay” with red and blue. Most operating systems also allow you to customize colors so that people with color blindness can see everything.

Color in machine vision

Machine vision in color is a fast-growing branch of artificial intelligence. Until recently, most of the work in this area took place with monochrome images, but now more and more scientific laboratories are working with color. Some algorithms for working with monochrome images are also used for processing color images.

Application

Machine vision is used in a number of industries, such as controlling robots, self-driving cars, and unmanned aerial vehicles. It is useful in the field of security, for example, for identifying people and objects from photographs, for searching databases, for tracking the movement of objects, depending on their color, and so on. Determining the location of moving objects allows the computer to determine the direction of a person's gaze or track the movement of cars, people, hands, and other objects.

In order to correctly identify unfamiliar objects, it is important to know about their shape and other properties, but color information is not so important. When working with familiar objects, on the contrary, color helps to recognize them faster. Working with color is also convenient because color information can be obtained even from low-resolution images. Recognizing the shape of an object, as opposed to color, requires high resolution. Working with color instead of object shape can reduce image processing time and use less computer resources. Color helps to recognize objects of the same shape, and can also be used as a signal or sign (for example, red is a signal of danger). In this case, you do not need to recognize the shape of this sign, or the text written on it. There are many interesting examples of the use of color vision on the YouTube website.

Processing color information

Photos processed by the computer are either uploaded by users or taken by the built-in camera. The process of digital photography and video shooting is well mastered, but the processing of these images, especially in color, is associated with many difficulties, many of which have not yet been resolved. This is due to the fact that color vision in humans and animals is very complex, and it is not easy to create computer vision similar to human vision. Vision, like hearing, is based on adaptation to the environment. The perception of sound depends not only on the frequency, sound pressure and duration of the sound, but also on the presence or absence of other sounds in the environment. So it is with vision - the perception of color depends not only on frequency and wavelength, but also on the characteristics of the environment. For example, the colors of the surrounding objects affect our perception of color.

From an evolutionary perspective, such adaptations are necessary to help us get used to our environment and to stop paying attention to insignificant elements, but to direct our full attention to what is changing in the environment. This is necessary in order to make it easier to spot predators and find food. Sometimes optical illusions occur due to this adaptation. For example, depending on the color of the surrounding objects, we perceive the color of two bodies differently, even when they reflect light with the same wavelength. The illustration shows an example of such an optical illusion. The brown square at the top of the image (second row, second column) appears lighter than the brown square at the bottom of the image (fifth row, second column). In fact, their colors are the same. Even knowing this, we still perceive them as different colors. Since our perception of color is so complex, it is difficult for programmers to describe all these nuances in algorithms for machine vision. Despite these difficulties, we have already achieved a lot in this area.

Unit Converter articles were edited and illustrated by Anatoly Zolotkov

Do you find it difficult to translate a unit of measurement from one language to another? Colleagues are ready to help you. Post a question to TCTerms and you will receive an answer within a few minutes.

Gigahertz taken, progress continues

Still, the processor life used to be more fun. About a quarter of a century ago, humanity crossed the 1 kHz barrier, and this dimension disappeared from the processor lexicon. The "power" of the processor began to be calculated in megahertz clock frequency (which, strictly speaking, is wrong). Three years ago, every 100 MHz step to increase the clock frequency was celebrated as a real event: with a long marketing artillery preparation, technological presentations and, in the end, a celebration of life. This was approximately until the frequency of the "desktop" processors reached 600 MHz (when the Mercedes namesake was mentioned in vain in every publication), and 0.18 microns became the main chip production technology. Then it became "uninteresting": the clock frequency was increased monthly, and at the end of last year Intel completely "undermined" the information market, announcing 15 new processors at the same time. Fifteen silicon microsensations fell on our heads like a lump, and the general festive spirit of the event was lost due to the discussion of the features of each chip presented. So it's no surprise that the two leading PC processor manufacturers (Intel and AMD) overcame the 1GHz bar too casually, pretending nothing special had happened. In the heap of Internet comments came across only one pretentious comparison with overcoming the sound barrier, and so - no fireworks and champagne. This is understandable: the plans of the developers have long been directed towards the gigahertz space. We will see the Intel Willamette crystal with a clock frequency of 1.3-1.5 GHz in the second half of this year, and we will talk about the features of the architecture, and not about cycles per second.

In my memory, the cherished gigahertz was actively talked about even more than a year ago, when on a hot Californian morning in the winter of 1999, Albert Yu demonstrated Pentium III 0.25 microns, operating at a frequency of 1002 MHz. Under the general applause of the audience, it was somehow forgotten that that demonstration resembled a trick. Later it became clear that the processor was "overclocked" in a cryogenic installation. There is even indirect evidence that the refrigerator was a serial KryoTech installation. One way or another, they forgot about the gigahertz for a year, although the processors got close enough to this frequency. It is curious that in the winter of 2000, the chairman of the board of directors of Intel, the legendary Andy Grove, with the assistance of Albert Yu, again repeated Intel's proven trick. At the IDF Spring'2000 forum, he demonstrated a test sample of the Intel Willamette processor operating at a clock frequency of 1.5 GHz. One and a half billion cycles per second - all at room temperature! It is gratifying that the Willamette is also a microprocessor with a new architecture, and not just a slightly improved Pentium III. But more on that below.

AMD has already had its own marketing gigahertz for a long time. The company officially cooperates with the "lords of the cold" from KryoTech, and the Athlon turned out to be quite a promising processor for overclocking in extreme cooling conditions. A gigahertz solution based on a cooled Athlon 850 MHz was available for sale back in January.

The marketing situation escalated somewhat when AMD began shipping limited quantities of 1GHz Athlon processors in a limited number of rooms. There was nothing to do, and Intel had to get the ace out of its sleeve - Pentium III (Coppermine) 1 GHz. Although the release of the latter was planned for the second half of the year. But it's not a secret for anyone that taking the gigahertz barrier is premature for both AMD and Intel. But they so wanted to be the first. You can hardly envy the two respectable companies that run around the only chair with the number 1 and wait in horror for the music to cut off. AMD just managed to sit down first - and it doesn't mean anything else. As in cosmonautics: humans were the first to be launched into the USSR, and the “second” Americans began to fly more often (and cheaper). Well, and vice versa: they are on the moon, and we said "fi", and all the enthusiasm was gone. However, the clock speed race has long had a purely marketing background: people, as you know, tend to buy megahertz, not performance indices. The clock frequency of the processor, as before, is a matter of prestige and a bourgeois indicator of the sophistication of a computer.

Another growing player in the microprocessor market, the Taiwanese company VIA, officially presented its first child a month ago. The microprocessor, formerly known under the codename Joshua, received the very original name Cyrix III and began to compete with the Celeron from below, in the niche of the cheapest computers. Of course, in the next year he will not see the frequency in gigahertz as his ears, but this "desktop" chip is interesting by the very fact of its existence in a hostile environment.

In this review, as always, we will focus on new products and plans of leading developers of microprocessors for PCs, regardless of whether they have overcome the gigahertz electoral barrier.

Intel Willamette - New 32-Bit Chip Architecture

Intel's 32-bit processor, codenamed Willamette (after the 306 km long Oregon river), will hit the market in the second half of this year. Based on the new architecture, it will be Intel's most powerful desktop processor, with a starting frequency well above 1 GHz (1.3-1.5 GHz expected). We've been shipping test samples of the processor to OEMs for almost two months now. The Willamette chipset is codenamed Tehama.

What is hidden under the mysterious term "new architecture"? For starters - support for an external clock frequency of 400 MHz (that is, the system bus frequency). That's three times faster than the vaunted 133 MHz supported by modern Pentium III class processors. In fact, 400 MHz is the resulting frequency: that is, the bus has a frequency of 100 MHz, but is capable of transmitting four chunks of data per cycle, which adds up to a 400 MHz analog. The bus will use a communication protocol similar to that of the P6 bus. The data transfer rate of this 64-bit synchronous bus is 3.2 GB / s. For comparison: the 133 MHz GTL + bus (the one used by modern Pentium IIIs) has a bandwidth of just over 1 GB / s.

The second distinctive feature of Willamette is support for SSE-2 (Streaming SIMD Extensions 2). This is a collection of 144 new instructions for optimizing your video, encryption, and Internet applications. SSE-2, of course, are compatible with SSE, first implemented in Pentium III processors. Therefore, Willamette will be able to successfully use hundreds of applications designed with SSE in mind. Willamette itself uses 128-bit XMM registers to support both integer calculations and floating point operations. Without going into details, the task of SSE2 is to compensate for the not strongest floating point block on the market. In the case of support for SSE2 from third-party software vendors (Microsoft with two hands "for"), no one will notice the substitution against the background of productivity growth.

And finally, the third key feature of the Willamette is deeper pipelining. Instead of 10 stages, 20 are now used, which can significantly increase the overall performance when processing certain complex mathematical applications and increase the clock speed. True, a "deep" pipeline is a double-edged sword: the processing time of an operation is sharply reduced, but the increasing delay time when processing interdependent operations can "compensate" for the increase in the productivity of the pipeline. To prevent this from happening, the developers had to increase the intelligence of the pipeline - to increase the accuracy of branch prediction, which exceeded an average of 90%. Another way to improve the efficiency of a long pipeline is by prioritizing (ordering) instructions in the cache. The function of the cache in this case is to arrange the instructions in the order in which they should be executed. This is somewhat similar to defragmenting a hard drive (only inside the cache).

Cache by cache, but the greatest criticism for a long time was caused by the performance of the block of integer computations in modern processors. The integer capabilities of processors are especially critical when running office applications (all sorts of Word and Excel). From year to year, both Pentium III and Athlon showed just ridiculous performance gains on integer calculations when the clock frequency was increased (the count was only a few percent). Willamett implements two modules of integer operations. So far, what is known about them is that each is capable of executing two instructions per clock. This means that at a core frequency of 1.3 GHz, the resulting integer frequency is equivalent to 2.6 GHz. And I emphasize, there are two such modules. That allows you to perform, in fact, four operations on integers per clock cycle.

The cache size is not mentioned in Intel's preliminary specification for Willamette. But there are "leaks" indicating that the L1 cache will be 256 KB in size (Pentium II / III has 32 KB L1 cache - 16 KB for data and 16 KB for instructions). The same aura of mystery surrounds the L2 cache size. The most likely option is 512 KB.

The Willamette processor, according to some information, will be supplied in cases with a matrix-pin arrangement of contacts for a Socket-462 socket.

AMD Athlon: 1.1 GHz Demo, 1 GHz Shipping

As if to recoup the previous strategy of following the leader, AMD nimbly clicked on the nose of the entire computer industry, demonstrating at the beginning of winter the Athlon processor with a clock frequency of 1.1 GHz (more precisely - 1116 MHz). Everyone decided they were joking. They say, well, she has successful processors, but everyone knows how long the time lag is between demonstration and mass production. But that was not the case: a month later, Advanced Micro Devices began serial deliveries of Athlon processors with a clock frequency of 1 GHz. And all doubts about their real availability were dispelled by Compaq and Gateway, which offered elite systems based on these chips. The price, of course, did not leave a particularly pleasant impression. A gigahertz Athlon costs about $ 1,300 in 1,000-unit batches. But it does have nice little brothers: Athlon 950 MHz ($ 1000) and Athlon 900 MHz ($ 900). However, there are few such processors, so prices are sky-high.

The Athlon 1116 MHz demonstrated earlier was remarkable in itself. Design standards - 0.18 microns, copper connections are used, heat dissipation is normal: it works at room temperature with a normal active radiator. But, as it turned out, it was not just Athlon (“just” aluminum interconnects), but Athlon Professional (codenamed Thunderbird). The actual appearance of such a processor on the market is expected only in the middle of the year (presumably in May). Only the frequency will be lower, and it will not cost "gigahertz dollars", but much cheaper.

So far, not much is known about the Athlon processor based on the Thunderbird core. It will use not Slot A (like modern Athlon versions from 500 MHz), but a matrix socket Socket A. Accordingly, the processor case will have a "flat" rather than a massive "vertical" cartridge. It is expected that by the summer processors based on the Thunderbird core will be released with clock frequencies from 700 to 900 MHz, and gigahertz will appear a little later. In general, taking into account the rate of price reduction for new processors, it becomes quite realistic to purchase a computer of an initial price range based on an Athlon 750 MHz or so by the New Year.

On the other hand, the still unannounced Spitfire processor remains the main contender for low-end computers in AMD's lineup. He is assigned the role of a junior competitor to Intel Celeron. Spitfire will be packaged for installation in a Socket A socket (power supply - 1.5 V), and its clock frequency by the beginning of autumn may reach 750 MHz.

IBM's multi-gigahertz ambitions at a glance

While the whole world rejoices in the old-fashioned way of taking a gigahertz, IBM talks about a technology that allows chips to be added by gigahertz per year. At least 4.5 GHz with existing semiconductor manufacturing technologies can be counted on. So, according to IBM, the IPCMOS (Interlocked Pipelined CMOS) technology developed by it will allow in three years to ensure the mass production of chips with a clock frequency of 3.3-4.5 GHz. At the same time, power consumption will be halved in relation to the parameters of modern processors. The essence of the new processor architecture is the use of distributed clock pulses. Depending on the complexity of the task, one or another processor unit will operate at a higher or lower clock frequency. The idea lay on the surface: all modern processors use a centralized clock frequency - all elements of the core, all computational units are synchronized with it. Roughly speaking, until all operations on one "loop" are completed, the processor will not start the next one. As a result, "slow" operations hold back fast ones. It also turns out that if you need to knock out a dusty carpet, then you have to shake the whole house. A decentralized clock frequency feed mechanism, depending on the needs of a particular block, allows fast microcircuit blocks not to wait for slow operations to be worked out in other blocks, but to do, relatively speaking, their own business. As a result, the overall energy consumption is also reduced (you only need to shake the carpet, not the whole house). IBM engineers are quite right when they say that it will become increasingly difficult to increase the synchronous clock speed from year to year. In this case, the only way is to use a decentralized clock frequency or even switch to fundamentally new (probably quantum) technologies for creating microcircuits .. Because of this name, it tempts to class it as the Pentium III. But this is a mistake. VIA itself positions it as a competitor to Intel Celeron, a processor for entry-level systems. But this turned out to be an overly arrogant act.

However, let's start with the merits of the new processor. It is designed to be installed in a Socket 370 socket (like Celeron). However, unlike Celeron, Cyrix III supports external clock frequency (system bus frequency) not 66 MHz, but 133 MHz - as in the most modern Pentium III Coppermine family. The second key advantage of Cyrix III is the on-chip L2 cache with a capacity of 256 KB - like the new Pentium III. The first level cache is also large (64 KB).

And finally, the third advantage is the support for the AMD Enhanced 3DNow! SIMD instruction set. This is really the first example of 3Dnow integration! for Socket 370 processors. AMD's multimedia instructions are already widely supported by software vendors, which will at least partially help compensate for the speed lag of the processor in graphics and gaming applications.

This is where all the good things end. The processor is manufactured using 0.18 micron technology with six metallization layers. At the time of its release, the "fastest" Cyrix III had a Pentium rating of 533. The real clock speed of the core is noticeably lower, therefore, since the time of independent Cyrix, it labeled its processors with "ratings" in relation to the clock speeds of Pentium, Pentium II, and later - Pentium III. It would have been better if they were counting from Pentium: the figure would have been more impressive.

The head of VIA Wen Chi Chen (in the past, by the way, an Intel processor engineer) was originally going to oppose Celeron with the low price of Cyrix III. How much it was possible - judge for yourself. The Cyrix III PR 500 starts at $ 84 and the Cyrix III PR533 starts at $ 99. In short, the Celeron is sometimes even cheaper. The first tests of the processor (carried out, of course, not in Russia) showed that its performance in office applications (where the emphasis is on integer computations) is not inferior to Celeron, but in multimedia the gap is obvious. Certainly not in favor of Cyrix III. Well, the first pancake is lumpy. However, VIA also has an integrated Samuel processor built on the IDT WinChip4 core. There the result may be better.

Alpha will also receive a well-deserved gigahertz

Compaq (the owner of part of the DEC legacy, including the Alpha processor) intends to release a 1 GHz version of the Alpha 21264 RISC server processor in the second half of the year. And its next chip - Alpha 21364 - starts exactly from this threshold frequency. In addition, the enhanced version of Alpha will be equipped with 1.5MB L2 cache and a Rambus memory controller.

ComputerPress 4 "2000

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1 megahertz [MHz] = 0.001 gigahertz [GHz]

Initial value

Converted value

hertz exahertz petahertz terahertz gigahertz megahertz kilohertz hectohertz decahertz decigertz santigertz millihertz microhertz nanohertz picohertz femtohertz attohertz cycles per second wavelength in exameters wavelength in petameters wavelength in terameters wavelength in megameters wavelength in kilometers in decameters wavelength in meters wavelength in decimeters wavelength in centimeters wavelength in millimeters wavelength in micrometers Compton wavelength of an electron Compton wavelength of a proton Compton wavelength of a neutron revolutions per second revolutions per minute revolutions per hour revolutions per day

Ferromagnetic liquids

More about frequency and wavelength

General information

Frequency

Frequency is a quantity that measures how often a particular periodic process repeats. In physics, frequency is used to describe the properties of wave processes. Wave frequency - the number of complete cycles of the wave process per unit of time. The SI unit of frequency is hertz (Hz). One hertz is equal to one oscillation per second.

Wavelength

There are many different types of waves in nature, from wind-induced sea waves to electromagnetic waves. The properties of electromagnetic waves depend on the wavelength. Such waves are divided into several types:

• Gamma rays with a wavelength of up to 0.01 nanometer (nm).
• X-rays with a wavelength of 0.01 nm to 10 nm.
• Waves ultraviolet which have a length of 10 to 380 nm. They are not visible to the human eye.
• Light in visible part of the spectrum with a wavelength of 380-700 nm.
• Invisible to humans infrared radiation with a wavelength from 700 nm to 1 millimeter.
• Infrared waves are followed by microwave, with a wavelength from 1 millimeter to 1 meter.
• The longest - radio waves... Their length starts from 1 meter.

This article is about electromagnetic radiation, and especially light. In it, we will discuss how wavelength and frequency affect light, including the visible spectrum, ultraviolet and infrared radiation.

Electromagnetic radiation

Electromagnetic radiation is energy, the properties of which are simultaneously similar to those of waves and particles. This feature is called wave-particle duality. Electromagnetic waves consist of a magnetic wave and an electrical wave perpendicular to it.

The energy of electromagnetic radiation is the result of the movement of particles called photons. The higher the frequency of radiation, the more active they are, and the more harm they can bring to the cells and tissues of living organisms. This is because the higher the frequency of the radiation, the more energy they carry. Great energy allows them to change the molecular structure of the substances on which they act. That is why ultraviolet, X-ray and gamma radiation are so harmful to animals and plants. A huge part of this radiation is in space. It is also present on Earth, despite the fact that the ozone layer of the atmosphere around the Earth blocks most of it.

Electromagnetic radiation and atmosphere

The earth's atmosphere only transmits electromagnetic radiation at a specific frequency. Most of gamma rays, X-rays, ultraviolet light, some infrared radiation, and long radio waves are blocked by the Earth's atmosphere. The atmosphere absorbs them and does not let them go further. Part of the electromagnetic waves, in particular, radiation in the short-wave range, is reflected from the ionosphere. All other radiation hits the surface of the Earth. In the upper atmospheric layers, that is, farther from the surface of the Earth, there is more radiation than in the lower layers. Therefore, the higher, the more dangerous it is for living organisms to be there without protective suits.

The atmosphere transmits a small amount of ultraviolet light to the Earth and is harmful to the skin. It is because of ultraviolet rays that people get sunburn and can even get skin cancer. On the other hand, some rays transmitted by the atmosphere are beneficial. For example, infrared rays that hit the Earth's surface are used in astronomy - infrared telescopes track infrared rays emitted by astronomical objects. The higher from the surface of the Earth, the more infrared radiation, therefore telescopes are often installed on mountain tops and other elevations. Sometimes they are sent into space to improve the visibility of infrared rays.

Relationship between frequency and wavelength

Frequency and wavelength are inversely proportional to each other. This means that as the wavelength increases, the frequency decreases and vice versa. It is easy to imagine: if the frequency of oscillations of the wave process is high, then the time between oscillations is much shorter than for waves, the oscillation frequency of which is less. If you imagine a wave on a chart, then the distance between its peaks will be the smaller, the more oscillations it makes over a certain period of time.

To determine the speed of propagation of a wave in a medium, it is necessary to multiply the frequency of the wave by its length. Electromagnetic waves in a vacuum always propagate at the same speed. This speed is known as the speed of light. It is equal to 299 & nbsp792 & nbsp458 meters per second.

Light

Visible light is electromagnetic waves of frequency and length that determine its color.

Wavelength and color

The shortest wavelength of visible light is 380 nanometers. It is purple, followed by blue and cyan, then green, yellow, orange, and finally red. White light consists of all colors at once, that is, white objects reflect all colors. This can be seen with a prism. The light entering it is refracted and lined up in a strip of colors in the same sequence as in a rainbow. This sequence is from the colors with the shortest wavelength to the longest. The dependence of the speed of propagation of light in matter on the wavelength is called dispersion.

A rainbow is formed in a similar way. Water droplets scattered in the atmosphere after rain behave like a prism and refract every wave. The colors of the rainbow are so important that in many languages ​​there are mnemonics, that is, a technique for memorizing the colors of the rainbow, so simple that even children can remember them. Many Russian speaking children know that "Every hunter wants to know where the pheasant is sitting." Some people come up with their own mnemonics, and this is a particularly useful exercise for children, because when they come up with their own method of remembering the colors of the rainbow, they will remember them faster.

The light to which the human eye is most sensitive is green, with a wavelength of 555 nm in light environments and 505 nm in twilight and darkness. Not all animals can distinguish colors. In cats, for example, color vision is not developed. On the other hand, some animals see colors much better than humans. For example, some species see ultraviolet and infrared light.

Light reflection

The color of an object is determined by the wavelength of light reflected from its surface. White objects reflect all waves of the visible spectrum, while black objects, on the contrary, absorb all waves and reflect nothing.

One of the natural materials with a high dispersion coefficient is diamond. Properly cut diamonds reflect light from both the outer and inner edges, refracting it, just like a prism. In this case, it is important that most of this light is reflected upward towards the eye, and not, for example, downward, into the frame, where it is not visible. Thanks to their high dispersion, diamonds shine very beautifully in the sun and under artificial light. Glass cut like a diamond also shines, but not as much. This is because, due to their chemical composition, diamonds reflect light much better than glass. The angles used when cutting diamonds are extremely important because corners that are too sharp or too obtuse either prevent light from reflecting off the interior walls or reflect light into the setting, as shown in the illustration.

Spectroscopy

Spectral analysis or spectroscopy is sometimes used to determine the chemical composition of a substance. This method is especially good if the chemical analysis of a substance cannot be carried out by working with it directly, for example, when determining the chemical composition of stars. Knowing what kind of electromagnetic radiation a body absorbs, you can determine what it consists of. Absorption spectroscopy, one of the branches of spectroscopy, determines which radiation is absorbed by the body. Such analysis can be done at a distance, therefore it is often used in astronomy, as well as in working with poisonous and dangerous substances.

Determination of the presence of electromagnetic radiation

Visible light, like all electromagnetic radiation, is energy. The more energy is emitted, the easier it is to measure this radiation. The amount of radiated energy decreases as the wavelength increases. Vision is possible precisely because humans and animals recognize this energy and sense the difference between radiation of different wavelengths. Electromagnetic radiation of different lengths is perceived by the eye as different colors. According to this principle, not only the eyes of animals and people work, but also technologies created by people for processing electromagnetic radiation.

Visible light

People and animals see a wide range of electromagnetic radiation. Most people and animals, for example, react to visible light and some animals are also exposed to ultraviolet and infrared rays. The ability to distinguish colors - not in all animals - some only see the difference between light and dark surfaces. Our brain determines the color as follows: photons of electromagnetic radiation enter the eye on the retina and, passing through it, excite the cones, photoreceptors of the eye. As a result, a signal is transmitted through the nervous system to the brain. In addition to cones, there are other photoreceptors, rods, in the eyes, but they are not able to distinguish colors. Their purpose is to determine the brightness and intensity of light.

There are usually several types of cones in the eye. There are three types in humans, each of which absorbs photons of light within specific wavelengths. When they are absorbed, a chemical reaction occurs, as a result of which nerve impulses with information about the wavelength enter the brain. These signals are processed by the visual cortex. This is the part of the brain responsible for the perception of sound. Each type of cone is responsible only for waves with a certain length, so to get a complete picture of the color, the information received from all the cones is added together.

Some animals have even more types of cones than humans. So, for example, in some species of fish and birds, there are from four to five types. Interestingly, some animal females have more types of cones than males. Some birds, such as seagulls that catch their prey in or on the water, have yellow or red oil droplets inside the cones that act as a filter. This helps them see more colors. The eyes of reptiles are arranged in a similar way.

Infrared light

In snakes, unlike humans, not only visual receptors, but also sensory organs that respond to infrared radiation... They absorb the energy of infrared rays, that is, they react to heat. Some devices, such as night vision goggles, also react to the heat generated by the infrared emitter. Such devices are used by the military, as well as to ensure the safety and security of premises and territory. Animals that see infrared light, and devices that can recognize it, see not only objects that are in their field of vision at the moment, but also traces of objects, animals, or people that were there before, if too a lot of time. For example, snakes can be seen if rodents have dug a hole in the ground, and police who use night vision devices can see if traces of a crime, such as money, drugs, or something else, have recently been hidden in the ground. Devices for recording infrared radiation are used in telescopes, as well as for checking containers and cameras for leaks. With their help, the place of heat leakage is clearly visible. In medicine, infrared images are used for diagnostics. In art history - to determine what is depicted under the top coat of paint. Night vision devices are used to guard premises.

Ultraviolet light

Some fish see ultraviolet light... Their eyes contain pigment that is sensitive to ultraviolet rays. Fish skin contains areas that reflect ultraviolet light that are invisible to humans and other animals - which is often used in the animal kingdom to mark the sex of animals, as well as for social purposes. Some birds also see ultraviolet light. This skill is especially important during the mating season when the birds are looking for potential mates. The surfaces of some plants also reflect ultraviolet light well, and the ability to see it helps in finding food. In addition to fish and birds, some reptiles, such as turtles, lizards, and green iguanas (pictured), see ultraviolet light.

The human eye, like the eyes of animals, absorbs ultraviolet light, but cannot process it. In humans, it destroys cells in the eye, especially in the cornea and lens. This, in turn, causes various diseases and even blindness. Despite the fact that ultraviolet light is harmful to vision, a small amount of it is necessary for humans and animals to produce vitamin D. Ultraviolet radiation, like infrared, is used in many industries, for example, in medicine for disinfection, in astronomy for observing stars and other objects. and in chemistry for the solidification of liquid substances, as well as for visualization, that is, to create diagrams of the distribution of substances in a certain space. With the help of ultraviolet light, counterfeit banknotes and passes are detected if signs are to be printed on them with special ink recognizable using ultraviolet light. In the case of counterfeiting documents, an ultraviolet lamp does not always help, as criminals sometimes use the real document and replace it with a photograph or other information, so that the markings for the UV lamps remain. There are many other uses for ultraviolet radiation as well.

Color blindness

Some people are unable to distinguish colors due to visual defects. This problem is called color blindness or color blindness, after the person who first described this feature of vision. Sometimes people can't see only colors at a certain wavelength, and sometimes they can't see colors at all. Often the cause is underdeveloped or damaged photoreceptors, but in some cases the problem lies in damage to the pathway of the nervous system, for example, in the visual cortex of the brain, where color information is processed. In many cases, this state creates inconveniences and problems for people and animals, but sometimes the inability to distinguish colors, on the contrary, is an advantage. This is confirmed by the fact that, despite the long years of evolution, color vision is not developed in many animals. People and animals that are color blind may, for example, see camouflage of other animals well.

Despite the benefits of color blindness, in society it is considered a problem, and for people with color blindness, the road to some professions is closed. Usually they cannot get full rights to fly the aircraft without restrictions. In many countries, driving licenses for these people also have restrictions, and in some cases they cannot get a license at all. Therefore, they cannot always find a job where they need to drive a car, an airplane, and other vehicles. They also find it difficult to find work where the ability to identify and use colors is of great importance. For example, they find it difficult to become designers, or work in an environment where color is used as a signal (for example, about danger).

Work is underway to create more favorable conditions for people with color blindness. For example, there are tables in which colors correspond to signs, and in some countries these signs are used in offices and public places along with color. Some designers do not use or limit the use of color to convey important information in their work. Instead of, or along with color, they use brightness, text, and other ways to highlight information so that even people who cannot distinguish colors can fully receive the information conveyed by the designer. In most cases, people with color blindness do not distinguish between red and green, so designers sometimes replace the combination “red = danger, green = okay” with red and blue. Most operating systems also allow you to customize colors so that people with color blindness can see everything.

Color in machine vision

Machine vision in color is a fast-growing branch of artificial intelligence. Until recently, most of the work in this area took place with monochrome images, but now more and more scientific laboratories are working with color. Some algorithms for working with monochrome images are also used for processing color images.

Application

Machine vision is used in a number of industries, such as controlling robots, self-driving cars, and unmanned aerial vehicles. It is useful in the field of security, for example, for identifying people and objects from photographs, for searching databases, for tracking the movement of objects, depending on their color, and so on. Determining the location of moving objects allows the computer to determine the direction of a person's gaze or track the movement of cars, people, hands, and other objects.

In order to correctly identify unfamiliar objects, it is important to know about their shape and other properties, but color information is not so important. When working with familiar objects, on the contrary, color helps to recognize them faster. Working with color is also convenient because color information can be obtained even from low-resolution images. Recognizing the shape of an object, as opposed to color, requires high resolution. Working with color instead of object shape can reduce image processing time and use less computer resources. Color helps to recognize objects of the same shape, and can also be used as a signal or sign (for example, red is a signal of danger). In this case, you do not need to recognize the shape of this sign, or the text written on it. There are many interesting examples of the use of color vision on the YouTube website.

Processing color information

Photos processed by the computer are either uploaded by users or taken by the built-in camera. The process of digital photography and video shooting is well mastered, but the processing of these images, especially in color, is associated with many difficulties, many of which have not yet been resolved. This is due to the fact that color vision in humans and animals is very complex, and it is not easy to create computer vision similar to human vision. Vision, like hearing, is based on adaptation to the environment. The perception of sound depends not only on the frequency, sound pressure and duration of the sound, but also on the presence or absence of other sounds in the environment. So it is with vision - the perception of color depends not only on frequency and wavelength, but also on the characteristics of the environment. For example, the colors of the surrounding objects affect our perception of color.

From an evolutionary perspective, such adaptations are necessary to help us get used to our environment and to stop paying attention to insignificant elements, but to direct our full attention to what is changing in the environment. This is necessary in order to make it easier to spot predators and find food. Sometimes optical illusions occur due to this adaptation. For example, depending on the color of the surrounding objects, we perceive the color of two bodies differently, even when they reflect light with the same wavelength. The illustration shows an example of such an optical illusion. The brown square at the top of the image (second row, second column) appears lighter than the brown square at the bottom of the image (fifth row, second column). In fact, their colors are the same. Even knowing this, we still perceive them as different colors. Since our perception of color is so complex, it is difficult for programmers to describe all these nuances in algorithms for machine vision. Despite these difficulties, we have already achieved a lot in this area.

Unit Converter articles were edited and illustrated by Anatoly Zolotkov

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