What is Webcam ?
Webcam feeds or streams its image in real time to or through a computer to a computer network. When “captured” by the computer, the video stream may be saved, viewed or sent on to other networks travelling through systems such as the internet, and e-mailed as an attachment. When sent to a remote location, the video stream may be saved, viewed or on sent there. Unlike an IP camera, a webcam is generally connected by a USB cable, or similar cable, or built into computer hardware, such as laptops. 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. In 2004, the oldest webcam still operating was FogCam at San Francisco State University, which had been running continuously since 1994.The term “webcam” 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. They are known for their low manufacturing cost and their high flexibility, making them the lowest-cost form of videotelephony. Despite the low cost, the resolution offered at present is rather impressive, with low-end webcams offering resolutions of 320×240, medium webcams offering 640×480 resolution, and high-end webcams offering 1280×720 or even 1920×1080 resolution. They have also become a source of security and privacy issues, as some built-in webcams can be remotely activated by spyware. They 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. They 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, automatic face tracking and autofocus, 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. They 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-publicised 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. Unauthorized access of webcams can present significant privacy issues. 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. FreeTrack 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 FreeTrack-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. A webcam’s CCD response is linear proportional to the incoming light. Therefore, webcams are suitable to record laser beam profiles, after the lens is removed. The resolution of a laser beam profiler depends on the pixel size. Commercial webcams are usually designed to record color images. The size of a webcam’s color pixel depends on the model and may lie in the range of 5 to 10µm. However, a color pixel consists of four black and white pixels each equipped with a color filter. Although these color filters work well in the visible, they may be rather transparent in the near infra-red. By switching a webcam into the Bayer-mode it is possible to access the information of the single pixels and a resolution below 3µm was possible. 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 videotelephony, 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 × 480 pixels. Both sender and receiver of the images must use 3D glasses to see the effect of three dimensional image. 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, 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-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 specification allows interconnectivity of webcams to computers without the need for proprietary device drivers. Microsoft Windows XP SP2, Linux and Mac OS X have UVC support built in and do not require extra device drivers, although they are often installed to add additional features. Many users do not wish the continuous exposure for which webcams were originally intended, but rather prefer privacy.Such privacy is lost when malware allow malicious hackers to activate the webcam without the user’s knowledge, providing the hackers with a live video and audio feed. This is a particular concern on many laptop computers, as such cameras normally cannot be physically disabled if hijacked by such a Trojan Horse program or other similar spyware programs. Cameras such as Apple’s older external iSight cameras include lens covers to thwart this. Some webcams have built-in hardwired LED indicators that light up whenever the camera is active, sometimes only in video mode. However, it is possible for malware to circumvent the indicator and activate the camera surrepticiously, as researchers demonstrated in the case of a MacBook’s built-in camera in 2013. Various companies sell sliding lens covers and stickers that allow users to retrofit a computer or smartphone to close access to the camera lens as needed. One such company reported having sold more than 250,000 such items from 2013 to 2016. However, any opaque material will work. Prominent users include former FBI director James Comey.The fraudulent process of attempting to hack into a person’s webcam and activate it without the webcam owner’s permission has been called camfecting. The remotely activated webcam can be used to watch anything within the webcam’s field of vision, sometimes the webcam owner itself. Camfecting is most often carried out by infecting the victim’s computer with a virus that can provide the hacker access to the victim’s webcam. This attack is specifically targeted at the victim’s webcam, and hence the name camfecting, a portmanteau of the words cam and infecting.In January 2005, some search engine queries were published in an online forum which allow anyone to find thousands of Panasonic- and Axis high-end web cameras, provided that they have a web-based interface for remote viewing. Many such cameras are running on default configuration, which does not require any password login or IP address verification, making them viewable by anyone. In the 2010 Robbins v. Lower Merion School District “WebcamGate” case, plaintiffs charged that two suburban Philadelphia high schools secretly spied on students – by surreptitiously remotely activating iSight webcams embedded in school-issued MacBook laptops the students were using at home — and thereby infringed on their privacy rights. School authorities admitted to secretly snapping over 66,000 photographs, including shots of students in the privacy of their bedrooms, including some with teenagers in various state of undress.The school board involved quickly disabled their laptop spyware program after parents filed lawsuits against the board and various individuals.