Webcam
From Wikipedia, the free encyclopedia
A web camera (or webcam, real camera) is a real-time camera (usually, though not always, a video camera) whose images can be accessed using the World Wide Web, instant messaging, or a PC video calling application.
Web-accessible cameras; typically involve a digital camera which uploads images to a web server, either continuously or at regular intervals. This may be achieved by a camera attached to a PC, or by dedicated hardware. Videoconferencing cameras typically take the form of a small camera connected directly to a PC. Analog cameras are also sometimes used (often of the sort used for closed-circuit television), connected to an video capture card and then directly or indirectly to the internet.
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[edit] History
Started in 1991, the first webcam was pointed at the Trojan room coffee pot in the computer science department of Cambridge University. This webcam is now defunct, as it was finally switched off on August 22, 2001. The final image captured by the camera can still be viewed at the webcam's homepage [1].
As with many new technologies, webcams and webcam chat found early commercial adoption and aggressive technology advancement through use by the pornography industry. The adult industry required 'live' images and requested a Dutch developer to write a piece of software that could do this without requiring web browser plugins. This led to the birth of the 'live streaming webcam', which is still available in various forms today.
[edit] Web-accessible cameras
In addition to use for personal videoconferencing, it was quickly realised that World Wide Web users enjoyed viewing images from cameras set up by others elsewhere in the world. While the term "webcam" refers to the technology generally, the first part of the term ("web-") is often replaced with a word describing what can be viewed with the camera, such as a nestcam or streetcam.
Today there are thousands of webcams that provide views into homes, offices and other buildings as well as providing panoramic views of cities (Metrocams) and the countryside. Webcams are used to monitor traffic with TraffiCams, the weather with WeatherCams and even volcanoes with VolcanoCams.
[edit] Software
Webcams connected to PCs can act as web-accessible cameras with certain software; the software uploads pictures to an FTP server, from which they can be made accessible to anyone, over the web.
Usually, this kind of software is programmed to work with almost every webcam. This software can be configured in many ways, and will often include options for image size and quality, overlaying logos, and time stamping images. Many different programs to do this are available, some of them free and open source.
[edit] Videoconferencing
As webcam capabilities have been added to instant messaging text chat services such as Yahoo Messenger, AOL Instant Messenger (AIM), Windows Live Messenger, and Skype, one-to-one live video communication over the internet has now reached millions of mainstream PC users worldwide. Increased video quality has helped webcams encroach on traditional video conferencing systems. New features such as lighting, real-time enhancements (retouching, wrinkle smoothing and vertical stretch) can make users more comfortable, further increasing popularity. Features and performance vary between programs.
[edit] Video security
Webcams are being used for security purposes. Software is available allowing PC-connected cameras to watch for movement and sound, recording both when they are detected; these recordings can be saved to the computer, e-mailed or uploaded to the internet. In one well-publicised case [1] a computer e-mailed out images as the burglar stole it, allowing the owner to give police a clear picture of the burglar's face even after the computer had been stolen.
[edit] Games
The EyeToy is a color digital camera device for the PlayStation 2, which allows players to interact with games using motion, colour detection and other means.
The Xbox Live Vision Camera is a camera designed for the Xbox 360 and Xbox Live, and can also be used for gaming applications like the EyeToy.
PC webcams can also be used for gaming applications using simple motion detection algorithms. Webcam games for PCs are available as either standalone executables, or they can even be played inside of a web browser window using Adobe Flash.
Also, any standard USB webcam will work with the Playstation 3.
[edit] Other applications
In astrophotography, webcams are a popular tool among amateurs (see also amateur astronomy) for speckle imaging or lucky imaging techniques. The webcam is attached to a telescope via a custom-made adaptor, and usually used in conjunction with barlow lenses and IR/UV cut-off filters. The video feed from the camera is then uploaded to a computer for processing.
[edit] Technology
Webcams typically include a lens, an image sensor, and some support electronics. Various lenses are available, the most common being a plastic lens that can be screwed in and out to set the camera's focus. 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. Consumer webcams usually offer a resolution in the VGA region, at a rate of around 25 frames per second. The higher resolution of 1.3 Megapixel is also available from the brands Microsoft, Kinamax, Sabrent, Logitech, and Vije.
Support electronics is present to 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. Some cameras - such as mobile phone cameras - use a CMOS sensor with supporting electronics 'on die', i.e. the sensor and the support electronics built on a single silicon chip, to save space and manufacturing costs.
[edit] Privacy
Some 'trojan horse' programs can allow malicious hackers to activate a computer's camera without the user's knowledge, providing the hacker with a live video feed from the unfortunate user's camera. Cameras such as Apple's iSight include lens covers to thwart this. Other webcams, such as the Logitech Communicate STX, have a built-in LED that lights up whenever the camera is active.
In mid-January 2005 some search engine queries were published in an on-line forum[2] which allow anyone to find thousands of Panasonic- and Axis-made high-end web cameras accessible through the web. Many such cameras are running on default configuration, which does not require any password login or IP address verification, making them visible to anyone.
[edit] See also
[edit] References
- ^ "Serial burglar caught on webcam" BBC News, 16th Feburary 2005, retrieved 3rd Janurary 2006
- ^ "Google exposes web surveillance cams" by Kevin Poulsen, The Register, 8th January 2005, retrieved 5th September 2006
[edit] External links
How to transform a standard webcam to an infrared cam - Public video showing the whole process and examples of use
