|PC web camera (webcam)|
|Monday, 23 October 2006|
A web camera system consists of a video camera plus software that runs on a personal computer to periodically upload an image from the camera to a web page. Software running on PC functions to periodically upload the captured video image to an Internet web page. The basic purpose of a web camera system is to post a reasonably live picture on a user-specified web page. Many webcam systems upload images on a periodic basis; for example, uploading an image once per hour. Using the Internet connection, the captured video information is transmitted from the personal computer of one user over the Internet to a personal computer of another user. A webcam may connect to a universal serial bus (USB) port of a personal computer and send video images to a browser that requests the images from the computer. Universal serial bus (USB) connections provide a flexible and adaptable method for connecting peripheral devices to computers. The ability of USB devices to "plug and play" as well as the wide array of USB devices available make USB devices a common staple of computing accessories. Webcams typically include a lens, an image sensor, and some support electronics. Image sensors can be CMOS or CCD. CMOS image sensors, when compared to charge-coupled-device (CCD) arrays, provide a low cost imaging semiconductor solution for web cameras and other optical sensing devices. Consumer webcams usually offer a resolution in the VGA region, at a rate of around 25 frames per second. Unlike more expensive analog or digital cameras for recording images on tape, PC cameras typically do not include a viewfinder. There is inherently a time delay between the point at which an image signal is supplied by a PC camera and the time at which the image is displayed on a monitor. On PC cameras, the lens is typically manually adjustable. A user manually adjusts the focus on a PC camera while viewing the preview image produced by the camera on the monitor.
In recent years, a growing number of personal computers and interactive television systems are equipped with digital video cameras. Such cameras may be used for two-way video communication (video conferencing) between systems connected by a communication network, such as a local area network or the Internet. Webcams have been increasingly used as a means to provide video images of meeting participants to other meeting participants. Webcam functions are incorporated into web-based conferencing applications which may be configured to display a low-resolution, low frames-per-second "headshot" view of a meeting participant on the desktop of another meeting participant. Video conferencing over internet involves sending a digitized video signal from a web camera to an internet service provider (ISP) connected to the internet or to a server. The digitized video signal is sent across the internet to one or more computers that may each display the video signal on a monitor. Information such as digitized video may be transmitted by packet switching between servers according to the TCP/IP protocol. This arrangement allows multiple computers to simultaneously share video with one another. Webcam capabilities have been added to instant messaging software such as Yahoo Messenger, AOL Instant Messenger (AIM), MSN Messenger, and Skype.