Webcam

A web camera (or webcam) is a real-time 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.

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 22 August 2001. The final image captured by the camera can still be viewed at the webcam's homepage .
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 using so called 'plugins'. This led to the birth of the 'live streaming webcam', which is still available in various forms today.

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.

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.
Many companies have tried to jump on the 'live video' bandwagon, most notably 'vdolive' (an Israeli company), Spotlife (a Logitech daughter company) and many others; most of these have since failed.

Video security

Webcams are being used for security purposes. Businesses are using webcams to monitor and record activity in offices, hallways and warehouses. Homeowners are monitoring everything from the baby's room to the backyard with webcams. A webcam alone cannot record video activity. Webcam monitoring software is needed in combination with a webcam to make a complete video security tool.

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 conjuction with barlow lenses and IR/UV cut-off filters. Video feed from the camera are then uploaded to a computer for processing.
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.

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. Consumer webcams usually offer a resolution in the VGA region, at a rate of around 25 frames per second. 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 bit of silicon, to save space.

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.
In mid-January 2005 two easy to use Google search strings were published in an on-line forum. These can find thousands of Panasonic- and Axis-made high-end web cameras. Many such cameras are running on default configuration, which does not require any password login or IP address verification, generating public controversy over webcam privacy issues.