Webcams characteristics types. Modern web cameras. How a webcam works

A digital webcam is a network device that consists of a video camera (CCD), a compression processor, and an embedded web server. Typically, a webcam is used as a device for organizing video filming, video conferencing or video surveillance and transmitting video over a LAN / WAN / Internet network. For the webcam to work on the network, no special devices and a personal computer are required. Depending on the settings, access to the video image received by the webcam can be open to all network users or only authorized users.

The device and principle of operation of the webcam

A modern webcam is a digital device that captures video, converts an analog video signal to digital, compresses a digital video signal and transfers video over a computer network. Therefore, the following components are included in the webcam:

CCD matrix,

lens,

optical filter,

video capture card,

video compression (compression) unit,

central processing unit and built-in web server,

flash memory,

network interface,

serial ports,

alarm inputs / outputs.

As a photodetector, most webcams use CCD ( CCD, CCD - Charge Coupled Device) is a rectangular photosensitive semiconductor plate with an aspect ratio of 3: 4, which converts the incident light into an electrical signal. The CCD consists of a large number of light-sensitive cells. In order to increase the light sensitivity of the CCD, a structure is often formed that creates a microlens in front of each of the cells. The technical parameters of a webcam usually indicate the format of the CCD matrix (the length of the matrix diagonal in inches), the number of effective pixels, the type of scan (progressive or interlaced) and the sensitivity.

Lens is a lens system designed to project an image of an object of observation onto the light-sensitive element of a webcam. The lens is an integral part of the webcam, therefore, the quality of the video image received by the webcam depends on the correct choice and installation. Quite often, a webcam comes with a lens. Lenses are characterized by a number of important parameters, such as focal length, aperture (F), depth of field, mount type (C, CS), format.

Optical infrared cut filters that are installed in webcams are optically accurate plane-parallel plates that are mounted on top of the CCD. They work as optical low-pass filters with a cutoff frequency of about 700 nm, near red. They cut off the infrared component of light waves, ensuring the correct color reproduction of the webcam. However, many black-and-white webcams do not have such filters, which makes monochrome webcams more sensitive.

Video capture card webcams (digitizing unit) convert the analog electrical signal generated by the CCD matrix into a digital format. The signal conversion process consists of three stages:

Sampling,

Quantization,

Coding.

Sampling- reading the amplitude of the electrical signal at regular intervals (period). This stage of signal conversion is characterized by the sampling rate.

Quantization is the process of digitizing sampling results. The change in the level of the electrical signal during the sampling period is represented in the form of a codeword of 8, 10 or 12 bits, which give respectively 256, 1024 and 4096 quantization levels. The accuracy of the digital representation of the signal depends on the number of quantization levels.

Coding. In addition to the information about the change in the signal level obtained at the previous stage, during the encoding process, bits are generated that indicate the end of the sync pulse and the beginning of a new frame, as well as additional error protection bits.

Compression unit webcams compress the digitized video signal into one of the compression formats (JPEG, MJPEG, MPEG-1/2/4, Wavelet). Thanks to compression, the size of the video frame is reduced. This is necessary for storing and transmitting video over the network. If the local network to which the webcam is connected has limited bandwidth, then in order to avoid overflowing network traffic, it is advisable to reduce the amount of information transmitted by reducing either the frame rate over the network or the frame resolution. Most of the compression formats that webcams use provide a reasonable compromise between the two solutions to the problem of transmitting video over a network. The currently known compression formats allow obtaining a digitized stream with a bandwidth of 64 Kb - 2 Mb (with such a bandwidth, video data streams can work in parallel with other data streams in networks).

Compression of video images in a webcam can be represented both by hardware and software. The software implementation of compression is cheaper, however, due to the high computational capacity of the compression algorithms, it is ineffective, especially when you need to view video from a webcam online. Therefore, most of the leading manufacturers produce webcams with hardware compression. For example, every network camera from AXIS Communications is equipped with an ARTPEC compression processor that compresses high-speed video into JPEG / MJPEG format.

CPU is the computing core of the webcam. It performs operations for the output of digitized and compressed video, and is also responsible for the functions of the embedded web server and control program for webcams.

Ethernet interface serves to connect the webcam to a 10/100 Mbps Ethernet network.

For networking, the webcam may have serial port to connect a modem and work in dial-up mode in the absence of a local network. The serial port can also connect peripheral equipment to the webcam.

Flash memory card allows you to update webcam control programs and store custom HTML pages.

RAM serves to store temporary data that is generated during the execution of control programs and user scripts. Many internet cameras have a so-called video buffer. This is the portion of RAM reserved for recording and temporarily storing video footage captured by the webcam. The information in the video buffer is updated cyclically, i.e. the new frame is written over the oldest one. This function is necessary if the webcam performs video surveillance, since it allows you to restore the events preceding and following the alarm from the security sensors connected to the webcam.

Alarm inputs / outputs serve to connect alarm sensors to the webcam. When one of the sensors is triggered, an alarm is generated, as a result of which the webcam processor assembles a set of frames recorded in the video buffer before, after and at the time of the alarm. This set of frames can be sent to a specified e-mail address or via FTP.

Connecting and installing a webcam

Typically, a webcam is connected to the Internet via the 10BaseT / 100BaseTX / 1000BaseTX Ethernet port or using a modem via a serial port. After the webcam is physically connected to the network, it is assigned an IP address. More often than not, a webcam does not have a default IP address; it is installed either using the appropriate function of a standard web browser, or by a DOS command that uses the serial number of the webcam assigned to it by the manufacturer for identification. In addition, manufacturers develop special programs for webcams that greatly simplify the procedure for assigning an IP address to a webcam (for example, IP Installer from AXIS Communications). With built-in software for web server, FTP server, FTP client, e-mail client, etc., the webcam connects directly to the LAN / WAN / Internet network and works as a standalone network device in it. This distinguishes webcams from other digital cameras, which require a mandatory connection to a personal computer via USB or LPT port. In addition, webcams can support custom scripts and JAVA applets.

To install a webcam outdoors or indoors, many manufacturers provide special fasteners in the design of the camera body, designed for installation on walls, ceilings, brackets and rotary devices. Some webcams have built-in PTZ devices for mounting on a horizontal or vertical surface.

Additional features and functions of the webcam

Motion Detector is a software module, the main task of which is to detect web cameras moving in the field of view at a video surveillance object. The motion detector not only detects movement in the image field, but also determines the size of the object and the speed of its movement. Depending on the video surveillance tasks, the webcam motion detector is configured to detect the movement of objects with the utmost minimization of false alarms (noise filtering), and flexible alarm processing logic is set (alarm recording, integration with other security equipment).

Audio transmission over the network, in most cases, it is carried out by connecting an additional audio module to the webcam. For example, AXIS Communications is releasing a special AXIS 2191 audio module to expand the functionality of webcams, which is compatible with most AXIS webcams.

Password protection serves to restrict access to the webcam to persons who do not have access rights.

By default, webcam video can be viewed from any networked computer that has a standard web browser such as Internet Explorer or Netscape Navigator installed. However, you can limit the number of persons with access rights to the webcam by entering a password at the user level. Many webcams support multi-level password protection to differentiate access and administration rights.

Webcam software

Typically, the webcam image can be viewed using a standard web browser such as Internet Explorer or Netscape Navigator. However, many manufacturers develop exclusive webcam software.

They combine the functions of a web browser and management software to control, configure and view images from a webcam (for example, AXIS Camera Explorer or JVC Professional's management software for V.networks network device administration). There is also distributed network video surveillance software that supports multi-vendor equipment such as Digicore Systems' Sphinx-DV.

Connecting the webcam to the network

Currently, a webcam can connect to the network in several ways, which are based on various data transfer standards.

10/100 MbitEthernet. This is the most popular way to transfer data from a webcam to the network. There are two standards for 10 Mbit Ethernet networks: 10Base2 (using coaxial cable) and 10BaseT (using twisted pair). 10Base2 is rarely used due to the sensitivity of the coaxial cable to external noise. The 100BaseTX standard uses twisted pair cables and provides a data transfer rate of 100 Mbps.

1000 Mbit Ethrnet, Gigabit Ethernet. The 1000BaseTX standard used here is an enhanced version of 100BaseTX. This standard is mainly used for building LAN backbones.

Standard telephone modems. This is a cheap and fairly common way to connect your webcam to the global network. The main disadvantage of this connection method is the low data transfer rate (the maximum data download speed is 56 kbps, the maximum swap speed is 33.6 kbps). The webcam is connected to the modem through a serial port.

ISDN modems. The ISDN (Integrated services Digital Network) standard is used to transmit digitized graphics, audio and video information and other digital data over private or public digital telephone networks. The ISDN standard provides data transmission from a web camera at speeds up to 128 kbps over two channels.

xDSL modems. DSL (Digital Subscriber Line) is a technology that provides high bandwidth over simple copper telephone wires. The data transfer rate of the webcam may vary depending on the service provider. On average, it is 1 Mbps for data download and 250 kbps for swap.

Cable modems. A cable modem is a modem that provides Internet access over cable television networks. Cable modems use asymmetric technology that is best suited for the user's Internet access. At the same time, the maximum possible speed of receiving data from a webcam with such a modem can reach about 40 Mbit / s (although usually it does not exceed 1 Mbit / s), and the data transfer rate is about 10 Mbit / s.

Cellular modems. With a cellular modem, you can connect your webcam to the Internet using cellular lines. The data transfer rate is usually between 5 and 20 kbps.

More detailed technical information on specific models of webcams from Axis Communications and JVC Professional is presented on the same website in the video cameras section. Brief technical characteristics and prices for webcams are given in the ARMO-System online store.

How to access your webcam over the Internet

How to access your webcam over the Internet.

Example: After you have already received the image from the webcam on your computer, you decide that it would be nice to be able to access the camera wherever the Internet is. For example, as a store owner, you want to monitor the activities in the store from your home, instead of having to be present every minute at the workplace.

Step 1: System Requirements

Scenario A)

If your building (where the camera should be located) is already connected via Ethernet to an Internet Service Provider (ISP), just set up an account, switch the network camera through the network output, and you should get a dynamically assigned public IP for the network camera. -address. Follow the installation commands for the network camera. A dedicated software or utility for the webcam will be helpful in identifying the IP address.

Since the assigned IP address may be changed by your ISP (due to the limited supply of IP addresses shared among its clients), you can find out how you can assign a specific IP address to the camera in Step 4 below.

Scenario B)

If your building is not equipped with Ethernet access, then in most cases you may need the following devices:

broadband modem for an asymmetrical digital subscriber line connection (usually supplied by your ISP) or cable TV

a broadband router, which can also be called an Internet Gateway, (A broadband router allows LAN users to share a single Internet connection. It also serves as an interface between the Internet, ISP and Local Area Network)

a switch that allows various devices from the network to communicate directly with each other and allows devices from the local network to have separate IP addresses),

NOTE: Most broadband routers have a built-in switch function, so no separate hardware is required.

network camera

local computer

remote surveillance computer

Step 2: Assign an IP address for your camera

Since a broadband router typically assigns automatic, local IP addresses to devices on the local network, such IP addresses have properties to change. A static (permanent) IP address is recommended for a network camera. To assign a static IP, find out the IP range of your router, for example, it could be 192.168.0.2 to 192.168.0.35. If you choose to use an out-of-range IP address such as 192.168.0.100 as a static IP address for the camera, it is likely that you will not risk your device colliding with other devices that receive automatic addresses.

Setting the IP address for your camera can be done in three different ways, as indicated in the camera manual. Once the IP address is assigned, set the subnet and gateway (this information can be obtained from the router), and configure the camera settings: password, registered users to ensure that access to the camera is restricted.

Step 3: port forwarding

A broadband router, as mentioned earlier, provides an interface between the Internet, ISP and LAN. The router obtains an external IP address from an ISP and supplies internal (local) IP addresses for devices on the local network.

To access a network camera that is permanently located on the local network, you must identify the external IP address of your router (see your router manual), and configure your router so that the external IP address is directed to the static, local IP address of the network camera. ... This process is called port opening; that is, when you print the external IP address of the router from any networked computer, the Internet locates your router, in turn redirects your request to the local IP address that is assigned to the network camera.

Launch a Web browser and access the embedded Web pages of the router by Logging In to Router Configuration Pages.

Find the menu item “port forwarding” (or similar), with a table similar to the one shown below:

Since the camera sends its video over HTTP, you must configure the HTTP service as follows:

Save the configuration in the router and exit the configuration pages. The configuration is complete. Any requests reaching the external IP address of the router on port 80 will now be sent to the IP address of the camera: 192.168.0.100.

If you want to make more than one network camera accessible over the Internet, then you must use additional (unofficial) ports on the router, such as 80xx and bind them to the network address of the IP camera.

Step 4: What can you do if your ISP frequently changes Dfi external IP address

Create an account in the DNS service that serves and register domain names (for example, www.nic.ru, etc.) and bind it to an external IP address. The domain name, such as www.web-kamera.ru, is understandable to the user, it is easy to remember, and you can assign your own network device to each domain, i.e. its IP address. Whenever the router's IP address changes, it will be automatically registered by the DNS service in order to update your IP address so that you can access your network camera at the same address.

Most broadband routers have native DNS support such as www.dyndns.org.

Another alternative: You can buy or rent a static external IP address from your ISP.

Found a typo? Highlight and press CTRL + Enter

11 June 2011

Webcams. Purpose, principle of operation and basic characteristics.

on the discipline (specialization) "Computer hardware"

Checked

Nikolskaya K.Yu.

student of group PS-170

Badalova A.A.

Abstract is protected

with an estimate

Chelyabinsk 2014

Badalova A.A. Webcams. Purpose, principle of operation and basic characteristics. - Chelyabinsk: SUSU, PS-170, 20 p., 4 ill., Bibliogr. list - 5 items.

The purpose of the essay is to learn about the purpose, principles of operation and the main characteristics of webcams.

The objectives of the abstract are to study the device and principle of operation of webcams, learn how to install webcams and connect them to the network, learn about the importance of webcams in the modern world.

The main characteristics of webcams, methods of connecting to the network are considered. Described programs for webcams and how to connect a webcam to the network.

1. Introduction (p. 4)

2. Definition (p. 5)

3. Webcam creation history (p. 6)

4. Design and operation of the webcam (p. 7-11)

5. Additional features and functions of webcams (p. 12)

6. Connecting the webcam to the network (p. 13-15)

7. Ways to use webcams (p. 16-17)

8. Programs for webcams (p. 18)

9. Conclusion (p. 19)

10. Bibliographic list (p. 20).

Introduction.

Webcams are becoming more and more part of our lives. They are used to build video systems for both geographically large and small objects. They are especially indispensable in the control and monitoring of remote points where there is a need to use unattended equipment. When you urgently need to install "temporary" cameras, webcams are indispensable, because their installation does not require pulling separate wires, and therefore installation will be quick and easy.

The aim of my work is to learn about the purpose, principles of operation and basic characteristics of webcams.

To do this, I will study the history of origin, the device and the main characteristics, as well as the scope of application of webcams, I will learn how to install and connect to the network.

Webcam concept.

The history of the creation of a webcam.

It all started in one of the Cambridge computer laboratories back in the early 90s of the last century, when the Global Web was just beginning its triumphant march across the planet. A group of scientists, 15-20 people, worked on a project in the field of network technologies. The working conditions were spartan - there was only one coffee machine for the entire team, which could not meet the needs of the entire team. The main work was carried out in the laboratory, the staff lived in the same building, but in a different part of it. To spur the thought process with a cup of invigorating drink, the participants in the scientific project were forced to frequent the corridor, which was located on the floor above, where the coffee maker was located. Often, such trips failed, as some colleagues had already managed to empty the coveted container. The situation demanded a non-standard solution, and it was found.
One of the computers in the lab had a frame grabber. A camera was connected to it, which was aimed at the object of observation. The same computer played the role of a web server using specially written software. Those who wanted to know if there was coffee had to run the client software on their computer that connected to the server. As a result, a black and white image was displayed on the remote computer in a small window, which was updated three times a minute. A note about this interesting complex was published in Comm-Week on January 27, 1992. Not so much time has passed since the first prototypes of IP cameras appeared, but they have already become a fully formed, separate class of devices that make everyday life easier, more convenient and more fun.

Figure 1. Snapshot from the first webcam

The device and principle of operation of the webcam.

CCD matrix,

lens,

optical filter,

video capture card,

video compression (compression) unit,

central processing unit and built-in web server,

flash memory,

network interface,

serial ports,

alarm inputs / outputs.

·
As a photodetector, most webcams use CCD ( CCD, CCD - Charge Coupled Device) is a rectangular photosensitive semiconductor plate with an aspect ratio of 3: 4, which converts the incident light into an electrical signal. The CCD consists of a large number of light-sensitive cells. In order to increase the light sensitivity of the CCD, a structure is often formed that creates a microlens in front of each of the cells. The technical parameters of a webcam usually indicate the format of the CCD matrix (the length of the matrix diagonal in inches), the number of effective pixels, the type of scan (progressive or interlaced) and the sensitivity.

· Lens is a lens system designed to project an image of an object of observation onto the light-sensitive element of a webcam. The lens is an integral part of the webcam, therefore, the quality of the video image received by the webcam depends on the correct choice and installation. Quite often, a webcam comes with a lens. Lenses are characterized by a number of important parameters, such as focal length, aperture (F), depth of field, mount type (C, CS), format.

· Optical infrared cut filters that are installed in webcams are optically accurate plane-parallel plates that are mounted on top of the CCD. They work as optical low-pass filters with a cutoff frequency of about 700 nm, near red. They cut off the infrared component of light waves, ensuring the correct color reproduction of the webcam. However, many black-and-white webcams do not have such filters, which makes monochrome webcams more sensitive.

· Video capture card webcams (digitizing unit) convert the analog electrical signal generated by the CCD matrix into a digital format. The signal conversion process consists of three stages:

Discretization, quantization, coding.

Sampling- reading the amplitude of the electrical signal at regular intervals (period). This stage of signal conversion is characterized by the sampling rate.

· Compression unit webcams compress the digitized video signal into one of the compression formats (JPEG, MJPEG, MPEG-1/2/4, Wavelet). Thanks to compression, the size of the video frame is reduced. This is necessary for storing and transmitting video over the network. If the local network to which the webcam is connected has limited bandwidth, then in order to avoid overflowing network traffic, it is advisable to reduce the amount of information transmitted by reducing either the frame rate over the network or the frame resolution. Most of the compression formats that webcams use provide a reasonable compromise between the two solutions to the problem of transmitting video over a network.

The currently known compression formats allow obtaining a digitized stream with a bandwidth of 64 Kb - 2 Mb (with such a bandwidth, video data streams can work in parallel with other data streams in networks).

· CPU is the computing core of the webcam. It performs operations for the output of digitized and compressed video, and is also responsible for the functions of the embedded web server and control program for webcams.

· Ethernet interface serves to connect the webcam to a 10/100 Mbps Ethernet network.

· Flash memory card allows you to update webcam control programs and store custom HTML pages.

· RAM serves to store temporary data that is generated during the execution of control programs and user scripts. Many internet cameras have a so-called video buffer. This is the portion of RAM reserved for recording and temporarily storing video footage captured by the webcam. The information in the video buffer is updated cyclically, i.e. the new frame is written over the oldest one. This function is necessary if the webcam performs video surveillance, since it allows you to restore the events preceding and following the alarm from the security sensors connected to the webcam.

· Alarm inputs / outputs serve to connect alarm sensors to the webcam. When one of the sensors is triggered, an alarm is generated, as a result of which the webcam processor assembles a set of frames recorded in the video buffer before, after and at the time of the alarm. This set of frames can be sent to a specified e-mail address or via FTP.

Figure 2. Webcam device.

5. Additional features and functions of the webcam

· Motion Detector is a software module, the main task of which is to detect web cameras moving in the field of view at a video surveillance object. The motion detector not only detects movement in the image field, but also determines the size of the object and the speed of its movement. Depending on the video surveillance tasks, the webcam motion detector is configured to detect the movement of objects with the utmost minimization of false alarms (noise filtering), and flexible alarm processing logic is set (alarm recording, integration with other security equipment).

· Audio transmission over the network, in most cases, it is carried out by connecting an additional audio module to the webcam. For example, AXIS Communications is releasing a special AXIS 2191 audio module to expand the functionality of webcams, which is compatible with most AXIS webcams.

· Password protection serves to restrict access to the webcam to persons who do not have access rights.

A webcam is a device that brings people closer together, which allows you not to feel how far away your loved one is.

Many now do not even imagine how they used to live without this invention, how they communicated with friends and relatives who live thousands of kilometers away. But thanks to the webcam, all boundaries have been erased and now at any time of the day you can see a person and communicate with him.

In addition to the fact that the webcam makes it possible to communicate with relatives who live abroad or with friends who live in other cities, it has become an integral part of the workflow in institutions and offices. The presence of a webcam at the desktop makes it possible to monitor the work of employees, hold online conferences or meetings with employees who work outside the central office.

Everyone knows how to communicate on Skype, but, unfortunately, not many users can choose a good webcam. But it is the camera that determines the image quality and other important points that make communication between people comfortable.

As such, there is no classification or types of webcams. All cameras can be roughly divided into computer, tablet, IP-cameras, wireless and game. But in reality, they are distinguished by such parameters - the resolution of the matrix, the quality of the optics, the type of attachment, the method of transferring information. The same parameters are used to select the required webcam.

It should be noted that IP cameras are mainly used to monitor an object or territory. Such cameras transmit a high-quality image at any time of the day, unlike their counterparts, which do not have any criteria for image quality. Therefore, when choosing a webcam, you should not rely on the characteristics described. You just need to turn on the camera and see how it works. At the same time, do not be afraid that the program will not work. Manufacturers create webcams that work with any application.

Main characteristics

Choosing a webcam is worth starting with research matrix type... There are two main types of CMOS and CCD. Webcams, which are designed for communication on the Internet, are equipped with a CMOS matrix. The CCD has better image quality than the first type. Therefore, it is installed in webcams, which are designed for security purposes. It is best to compare the image quality with CMOS and CCD when choosing a camera. Then make a purchase.

Resolution abilities- another important point that affects the quality of the image. The minimum webcam resolution is 0.3 megapixels, i.e. 320x240 pixels, which will be enough for video conferencing. The maximum webcam resolution is 2592x1944 pixels. The best resolution for webcams is 640x480 and 1280x960 pixels, which allows you to clearly see the interlocutor, take pictures and videos. At the same time, one should not hope that the video or photograph will be clear, as on a camera or camcorder. Still, the pictures are slightly blurry. A webcam is, first of all, a tool for communicating with people. Therefore, the low resolution is compensated by other good parameters.

Optician a, installed on webcams affects the quality of the picture. Manufacturers are trying to install high-quality optics. It can go in both expensive and budget models. High-quality glass optics, for example, include Carl Zeiss. The type of optics is indicated in the characteristics of the device in the store or on the packaging.

Frame frequency is a parameter to be careful about. The frame rate ranges from 9 to 90Hz. A low frequency will transmit the image as a slideshow. Higher frame rates may not be compatible with Internet speeds, and as a result, communication will not be possible. The best option is 40 - 70Hz. But still, you should take into account the speed of the Internet, for example, for Wi-Fi, you should choose an average frame rate.

The next parameter that affects the image quality is matrix sensitivity... The quality of the image in a particular illumination depends on the level of sensitivity of the matrix. If the sensitivity of the matrix is not high, then poor illumination will interfere with the transmission of the picture.

Communication is hard to imagine without a microphone. Therefore, if a webcam is chosen for a personal computer, then a microphone must be provided in its model. If for a laptop, netbook or tablet, then the microphone is already built into them.

Mount type... For this parameter, everything is quite simple. If you need to mount it to the monitor, then choose a model with the appropriate mount. The webcam can just stand on the table if there is a lot of space. To perform security functions, cameras are chosen that are mounted on a wall or a pole (if surveillance is carried out on the street). Therefore, everyone chooses what is more convenient for him.

There are two ways to connect a webcam - via a USB cable or a modem. They mainly use the first connection method, because the speed will always be high. If you use a modem, then the speed will depend directly on the provider. The third connection method is less common, because it is used in expensive webcam models - wireless. It can only be used if Wi-Fi is available.

The last point to look out for when choosing a webcam is operating system compatibility. One thing should be said here, almost all models of webcams work with the Windows operating system and are not suitable for other systems.

Additional features of webcams

Zoom and backlight. For a camera or camcorder, these functions would be much more important than for a webcam. They still will not improve the image quality to the same state as in a camera. At the same time, the presence of zoom and illumination testifies to the good assembly of the device.

Autofocus is a good thing, especially if you plan to move your webcam frequently or take photos and videos. The distance to the subject will always be adjusted.

Many manufacturers add a change in the shooting mode to the additional features of the webcam (for example, sepia, black and white photo, white balance, etc.). In principle, they will be useful for filming, but not for Skype communication. Although it is worth processing photos in a program specially designed for this.

Webcam manufacturers

Answering this question, the first thing that comes to mind is the well-known companies that are engaged in the production of electronics, i.e. Samsung, LG and Philips. In addition, webcams are available from HP, Bravis and Microsoft. Of course, there are other manufacturers less popular than those listed. The most popular are webcams from Genius, Logitech and Creative. They ensure the high quality of their products.

You can buy goods from these companies not only in specialized stores, but also in online stores, where quality is also guaranteed.

The pricing policy is different. It depends not only on the brand, but also on additional features. When choosing a webcam, it is worth remembering one thing - the most expensive does not mean the best. You can buy an inexpensive webcam and get a high-quality image when communicating with relatives. The cost of webcams varies from 300 to 6100 rubles.

Using a webcam is easy enough. Special programs allow you to set up Skype, and the camera will only have to be connected to it

When using a webcam, it is important not to touch the optics and secure it securely so that it does not fall.

Thus, the best option for home use and communication on Skype will be a webcam with a resolution of 640x480 pixels, a USB cable for connection, with a built-in microphone and with the function of automatically adjusting the image based on the lighting in the room.

A webcam is a device that is most often bought at the same time as a computer and does not attach much importance to it. However, it is worth paying attention to the characteristics, otherwise disappointment and irritation may appear already at the first shooting or communication session.

By following our tips, you can learn all about the capabilities, functions and applications of webcams. We hope that this information will help readers make the right choice when purchasing a device.

What is a webcam, how does it work and where it is used

A webcam is a fairly small device, which is a photo or video camera connected to a computer or laptop. Webcams capture the image in real time and then transmit it to the addressee using the Internet. The difference from a digital camera, first of all, lies in the power supply by wires and the impossibility of functioning without a computer, at least fully.

Webcams are used for video chats and video calls, video conferencing, security purposes, for monitoring and surveillance, etc.

Main characteristics of webcams

The characteristics of webcams affect both the quality of the device and its price, which can vary greatly from model to model. What are the main parameters and what should not be missed when choosing a webcam?

Webcam matrix type. The webcam matrix can be created using one of the technologies:

a) CCD- technology used in digital cameras and also used for webcams. Among its advantages: high sensitivity, high duty cycle, efficiency - about 95%, lower noise level during operation. It is worth remembering that a power supply that is too weak is likely to fail at the time of maximum load of the system or even of its individual elements. A power supply that is too powerful can reduce the efficiency of the entire computer;

b) CMOS is a cheaper-to-manufacture technology used in most webcams. Such matrices have a low cost, shoot up to 500 frames per second, and consume quite little power during operation. Among their shortcomings, experts point out a large amount of noise in the image, a low pixel fill factor and, as a result, low sensitivity;

c) BSI CMOS- when using such a matrix, it becomes easier for light to hit the photodiodes. These sensors are also called "backlit sensors" - they are much more sensitive to light. Due to this, the amount of noise in the image is reduced compared to conventional CMOS.

Camera resolution is another of the most important characteristics. The quality of the transmitted image depends on it. Please note that the resolution can be direct and interpolated. With software interpolation, the number of pixels in the original image is processed using mathematical methods, multiplied by a certain number, and then an enlarged image is formed. In this case, the original image resolution does not change, and the quality may deteriorate. When choosing a camera, you should pay attention to the real resolution of 1.3 megapixels - this is enough for HD quality.
Frame frequency- a characteristic responsible for the smoothness of shooting. An acceptable rate of shooting is 15 frames per second - this will be enough for communication on the Web. For high-quality video broadcasts, you need at least 30 frames per second.
Focusing webcams allow you to influence the clarity of the image. It can be either manual or automatic. Manual is carried out by rotating the wheel located at the lens. Automatic focusing assumes that the webcam itself sets the distance to the object and calculates the focal length. The speed and quality of autofocus may vary significantly from model to model.
Sensitivity- the parameter of the minimum allowable illumination at which it is possible to use the camera. However, when buying a camera with infrared illumination, this characteristic will immediately be presented at a decent level.
Connection type... Typically, webcams are connected via USB version 1.1, 2.0, or 3.0. The latter type is faster, but only found on modern computers.

Additional functions of webcams:

Built-in microphone. Eliminates the need to buy another device, allows video calls to be made by large companies. Almost all cameras now have a built-in microphone.
The ability to use your webcam as a camera. Modern models of webcams allow these devices to be used as digital cameras. If you choose a camera for these purposes, pay attention to devices with a higher resolution, otherwise the quality of the photos will hardly suit you. Some cameras are also equipped with a photo button on the body - pressing it can activate the photo mode and launch the graphics editor.
Availability of special software. Each webcam manufacturer offers its own software for users to install or use. In addition to standard functions, it can add personalized features to the camera. For example, Logitech offers a built-in graphics editor.

What else should you pay attention to?

When choosing and buying a webcam, pay attention to its mount, tilt and swivel capabilities, as well as the viewing angle.

Study the characteristics, compare webcam models, take into account the tips from our review and enjoy comfortable and pleasant video communication.

A webcam is a digital camera connected to a computer. The device is designed to scan, process and transmit images over the Internet in real time. Most often used for online broadcasts and video calls.

Historic coffee stream

The first webcam is an invention of the Cambridge geniuses Quentin Stafford-Fraser and Paul Jardetsky. The device appeared in 1991 thanks to the love of the university staff for coffee. At that time, there was only one coffee pot in the Trojan Room for the entire computer development department. Scientists often had to go a long way for a mug of this wonderful drink in vain. So that everyone can see if coffee is ready without leaving the workplace, a web camera was created.

Initially, the image was broadcast only to the working computers of the department via the local network and was 128 × 128 pixels in size. The development received the client name XCoffee under the Window System. The online broadcast lasted 10 years. In 2001, despite protests from fans, the camera was turned off. The coffee pot became a famous rarity and was sold on eBay for £ 3,350.

Modern webcam device

The main part of the webcam is the image sensor, or CCD matrix. It is a semiconductor chip made up of millions of tiny light-sensitive squares arranged in a grid. These squares are called pixels. Basic webcams use relatively small sensors, only a few hundred thousand pixels.

In addition to a CCD or ROM matrix, the camera contains a lens, an analog-to-digital converter, also called a video capture card, a microprocessor, and a compressor. Some models of IP cameras contain a built-in web server and RAM.

How a webcam works

A standard webcam is a separate device connected to your computer. It acts as follows:

Through a lens in the front, the camera captures light and projects it onto an integrated circuit chip made up of microscopic light detectors.
The video capture card converts an analog image into a digital one, that is, into a bytecode of zeros and ones.
Compressor units compress the digital signal into MJPEG or MPEG formats.
Then the information is transmitted to a computer via a USB interface, and then to the Internet.

In the case of IP cameras, a connection to a computer is not required. The device has its own IP address, thanks to the built-in web server, and the streaming is done directly to the network.

Webcam parameters

If you disassemble two webcams in parts, you get an identical set of parts: a board with a photosensitive matrix and a lens. So how do you know which works well and which doesn't?

Resolution - the number of pixels vertically and horizontally of the matrix. The more there are, the better and more expensive the device is. Modern HD webcams transmit images in real time with a resolution between 1280 × 720 and 1600 × 1200, that is, 3-2.0Mpx. For budget models, this parameter is 320 × 240 or 640 × 480. The picture is grainy, sometimes blurry. But not every internet connection will pull a 2.0Mpx camera. If the data transfer rate is low, up to 10-20 Mb, the image will freeze.
FPS is the number of frames per second that the camera is capable of processing. Inexpensive models have a frequency of about 24 frames per second, for PRO cameras this value reaches 50-60. Medium cameras like the Microsoft VX-1000 or VS-800 have a frame rate of 30 frames per second with a resolution of 640x480. If you sit still during video chat, then even with low fps the image will be quite clear. But for shooting in motion, the frequency must be higher than 40 frames per second.

These are two key parameters that determine the level of the webcam. There are additional options that have almost no effect on the quality of the device and the image. Basically, they affect the price, and not always justifiably.

What is a webcam for?

The task of a webcam is to show objects that are out of sight and reach. With its help, you can remotely monitor people, rooms in real time. For example, if you are going to another city or by the sea, the webcam will show the weather better than any forecaster.

90% of users purchase a gadget for video calls, chats and video conferencing over the Internet. To do this, a special software that supports VoIP must be installed on the computer: Skype, ooVoo or Viber. Instead of client programs, you can use the Appear.in or Hangouts browser extensions. But on video chats, the range of camera capabilities does not end there:

Online broadcasts of what is happening in the most popular corners of the world. Webcams in Sochi, New York and near Niagara Falls allow you to travel without leaving your computer chair.
Security companies and security services widely use this technique to monitor objects.
Video from a webcam can be recorded, edited, posted on the Internet, on forums, in a YouTube playlist or on a blog. For these purposes, there are many programs, one of which is Windows Movie Maker or Camtasia Studio.
Using web applications, create emails in video format.
Conduct paid training webinars and make money using the gadget.

Unconventional ways to use your webcam

Broadcasts from webcams on the sea, embankments, from the eagle's nest in the Himalayas are no longer surprising. But there are some unusual and fun ways to use the gadget:

OvO Webcam Games or GloopIt Webcam Utility. Participants control their characters via a webcam. For such entertainment, the monitor needs to be aimed at yourself and the movements of all parts of the body to complete quests. Game software is downloaded from the Internet and installed on a computer.
Use gesture recognition technology to control software on the desktop, YouTube, Pandora, Grooveshark and Netflix players in the Chrome browser. No mouse or keyboard is used, only the movement of the brushes. The development is called Flutter and is still in alpha testing.
Create animated GIFs and avatars using WebCam Avatar or PsykoGif.
Use to log into your account without entering a password.

From a webcam with built-in microphone, PC and Skype, every attentive parent can mount a baby monitor. To do this, in the messenger, you need to create a new account in the name of the child, add yourself and your relatives to the list of contacts. Set Skype to automatically answer a video call and turn on the camera. The computer with the gadget must be installed so that the entire nursery is visible, including the child itself. With this know-how, the child can be observed at any time.