A webcam is a video camera that feeds or streams its image in real time to or through a computer to computer network. When "captured" by the computer, the video stream may be saved, viewed or sent on to other networks via systems such as the internet, and email as an attachment. When sent to a remote location, the video stream may be saved, viewed or on sent there. Unlike an IP camera (which connects using Ethernet or Wi-Fi), a webcam is generally connected by a USB cable, or similar cable, or built into computer hardware, such as laptops.
More: Test your Webcam Online
The term 'webcam' (a clipped compound) may also be used in its original sense of a video camera connected to the Web continuously for an indefinite time, rather than for a particular session, generally supplying a view for anyone who visits its web page over the Internet. Some of them, for example, those used as online traffic cameras, are expensive, rugged professional video cameras.
Webcams are known for their low manufacturing cost and flexibility, making them the lowest cost form of video telephony. Despite the low cost, the resolution offered at present (2015) is rather impressive, with low end webcams (<offering resolutions of 320x240, medium webcams offering 640x480 resolution, and high-end webcams offering 1280x720 (aka 720p) or even 1920x1080 (aka 1080p) resolution.
They have also become a source of security and privacy issues, as some built-in webcams can be remotely activated via spyware.
Webcams are known for their low manufacturing cost and flexibility, making them the lowest cost form of video telephony. Despite the low cost, the resolution offered at present (2015) is rather impressive, with low end webcams (<offering resolutions of 320x240, medium webcams offering 640x480 resolution, and high-end webcams offering 1280x720 (aka 720p) or even 1920x1080 (aka 1080p) resolution.
They have also become a source of security and privacy issues, as some built-in webcams can be remotely activated via spyware.
Uses
most popular use of webcams is the establishment of video links, permitting computers to act as videophones or video conference stations. Other popular uses include security surveillance, computer vision, video broadcasting, and for recording social videos.
The video streams provided by webcams can be used for a number of purposes, each using appropriate software:
Health care
Most of the modern webcams allow to capture arterial pulse rate by means of simple algorithmic trick. Researchers claim that accuracy of such measurements about plus minus 5 bpm.
Video monitoring
Webcams may be installed at places such as childcare centers, offices, shops and private areas to monitor security and general activity.
Commerce
Webcams have been used for Augmented Reality experiences online. One such function has the webcam act as a 'magic mirror' to allow an online shopper to view a virtual item on themselves. The Webcam Social Shopper is one example of software that utilizes the webcam in this manner.
Videocalling and videoconferencing
Further information: Videophone, Videoconferencing, and Video telephony
Webcam can be added to instant messaging, text chat services such as AOL Instant Messenger, and VoIP services such as Skype, one-to-one live video communication over the Internet has now reached millions of mainstream PC users worldwide. Improved video quality has helped webcams encroach on traditional video conferencing systems. New features such as automatic lighting controls, real-time enhancements (retouching, wrinkle smoothing and vertical stretch), automatic face tracking and auto-focus, assist users by providing substantial ease-of-use, further increasing the popularity of webcams.
Webcam features and performance can vary by program, computer operating system, and also by the computer's processor capabilities. Video calling support has also been added to several popular instant messaging programs.
Video security
Webcams can be used as security cameras. Software is available to allow PC-connected cameras to watch for movement and sound, recording both when they are detected. These recordings can then be saved to the computer, e-mailed, or uploaded to the Internet. In one well-publicized case, a computer e-mailed images of the burglar during the theft of the computer, enabling the owner to give police a clear picture of the burglar's face even after the computer had been stolen.
Recently webcam privacy software has been introduced by such companies such as Stop Being Watched or Webcam lock. The software exposes access to a webcam and prompts the user to allow or deny access by showing what program is trying to access the webcam. Allowing the user to accept a trusted program the user recognizes or terminate the attempt immediately. Other companies on the market manufacture and sell sliding lens covers that allow users to retrofit the computer and close access to the camera lens.
Video clips and stills
Webcams can be used to take video clips and still pictures. Various software tools in wide use can be employed for this, such as Pic Master (for use with Windows operating systems), Photo Booth (Mac), or Cheese (with Unix systems). For a more complete list see Comparison of webcam software.
Input control devices
Special software can use the video stream from a webcam to assist or enhance a user's control of applications and games. Video features, including faces, shapes, models and colors can be observed and tracked to produce a corresponding form of control. For example, the position of a single light source can be tracked and used to emulate a mouse pointer, a head mounted light would enable hands-free computing and would greatly improve computer accessibility. This can be applied to games, providing additional control, improved interactivity and immersiveness.
Free Track is a free webcam motion tracking application for Microsoft Windows that can track a special head mounted model in up to six degrees of freedom and output data to mouse, keyboard, joystick and Free Track-supported games. By removing the IR filter of the webcam, IR LEDs can be used, which has the advantage of being invisible to the naked eye, removing a distraction from the user. TrackIR is a commercial version of this technology.
The EyeToy for the PlayStation 2, PlayStation Eye for the PlayStation 3, and the Xbox Live Vision camera and Kinect motion sensor for the Xbox 360 and are color digital cameras that have been used as control input devices by some games.
Small webcam-based PC games are available as either standalone executables or inside web browser windows using Adobe Flash.
Astro photography
With very-low-light capability, a few specific models of webcams are very popular to photograph the night sky by astronomers and astro photographers. Mostly, these are manual focus cameras and contain an old CCD panel instead of comparatively newer CMOS panels. The lenses of the cameras are removed and then these are attached to telescopes to record images, video, still, or both. In newer techniques, videos of very faint objects are taken for a couple of seconds and then all the frames of the video are 'stacked' together to obtain a still image of respectable contrast. Philips PCVC 740K and SPC 900 are two of the few webcams liked by astro photographers.
History
Early development
First developed in 1991, a webcam was pointed at the Trojan Room coffee pot in the Cambridge University Computer Science Department. The camera was finally switched off on August 22, 2001. The final image captured by the camera can still be viewed at its homepage. The oldest webcam still operating is FogCam at San Francisco State University, which has been running continuously since 1994. A cam developed for CNN was later destroyed during Desert Shield/Storm.
Connectix QuickCam
The first commercial webcam, the black-and-white QuickCam, entered the marketplace in 1994, created by the U.S. computer company Connectix (which sold its product line to Logitech in 1998). QuickCam was available in August 1994 for the Apple Macintosh, connecting via a serial port, at a cost of $100. Jon Garber, the designer of the device, had wanted to call it the "Mac-camera", but was overruled by Connectix's marketing department; a version with a PC-compatible serial port and software for Microsoft Windows was launched in October 1995. The original QuickCam provided 320x240-pixel resolution with a grayscale depth of 16 shades at 60 frames per second, or 256 shades at 15 frames per second. These cam were tested on several Delta II launch using a variety of communication protocols including CDMA, TDMA, GSM and HF.
In 2010, Time Magazine named the QuickCam as one of the top computer devices of all time.
Videoconferencing via computers already existed, and at the time client-server based videoconferencing software such as CU-SeeMe had started to become popular.
Later developments
One of the most widely reported-on webcam sites was JenniCam, created in 1996, which allowed Internet users to observe the life of its namesake constantly, in the same vein as the reality TV series Big Brother, launched four years later. Other cameras are mounted overlooking bridges, public squares, and other public places, their output made available on a public web page in accordance with the original concept of a "webcam". Aggregator websites have also been created, providing thousands of live video streams or up-to-date still pictures, allowing users to find live video streams based on location or other criteria.
Around the turn of the 21st century, computer hardware manufacturers began building webcams directly into laptop and desktop screens, thus eliminating the need to use an external USB or FireWire camera. Gradually webcams came to be used more for telecommunications, or video telephony, between two people, or among several people, than for offering a view on a Web page to an unknown public.
For less than US$100 in 2012, a Three-dimensional space webcam became available, producing videos and photos in 3D Anaglyph image with a resolution up to 1280 x 480 pixels. Both sender and receiver of the images must use 3D glasses to see the effect of three dimensional image.
Technology
Webcams typically include a lens, an image sensor, support electronics, and may also include a microphone for sound. Various lenses are available, the most common in consumer-grade webcams being a plastic lens that can be screwed in and out to focus the camera. Fixed focus lenses, which have no provision for adjustment, are also available. As a camera system's depth of field is greater for small image formats and is greater for lenses with a large f-number (small aperture), the systems used in webcams have a sufficiently large depth of field that the use of a fixed focus lens does not impact image sharpness to a great extent.
Image sensors can be CMOS or CCD, the former being dominant for low-cost cameras, but CCD cameras do not necessarily outperform CMOS-based cameras in the low cost price range. Most consumer webcams are capable of providing VGA resolution video at a frame rate of 30 frames per second. Many newer devices can produce video in multi-megapixel resolutions, and a few can run at high frame rates such as the PlayStation Eye, which can produce 320×240 video at 120 frames per second.
Support electronics read the image from the sensor and transmit it to the host computer. The camera pictured to the right, for example, uses a Sonix SN9C101 to transmit its image over USB. Typically, each frame is transmitted uncompressed in RGB or YUV or compressed as JPEG. Some cameras, such as mobile phone cameras, use a CMOS sensor with supporting electronics "on die", i.e. the sensor and the support electronics are built on a single silicon chip to save space and manufacturing costs. Most webcams feature built-in microphones to make video calling and videoconferencing more convenient.
The USB video device class (UVC) specification allows for inter-connectivity of webcams to computers without the need for proprietary device drivers. Microsoft Windows XP SP2, Linux and Mac OS X (since October 2005) have UVC support built in and do not require extra device drivers, although they are often installed to add additional features.
