Frame grabber

A frame grabber is an electronic device that captures (i.e., "grabs") individual, digital still frames from an analog video signal or a digital video stream. It is usually employed as a component of a computer vision system, in which video frames are captured in digital form and then displayed, stored or transmitted. Early frame grabbers typically had only enough memory to store a single digitized video frame, hence the singular "frame" in the device name, whereas modern frame grabbers often can store multiple frames.

Historically, frame grabber expansion cards were the predominant way to interface cameras to PC's. Other interface methods have emerged since then, with frame grabbers (and in many case, cameras themselves) connecting to computers via interfaces such as USB, Ethernet and IEEE 1394 ("FireWire").

Modern frame grabber devices often perform functions beyond capturing a single video input. For example, some devices can capture audio in addition to video, and some provide multiple video inputs that are captured concurrently. Other operations may be performed as well, such as deinterlacing, text or graphics overlay, image transformations (e.g., resizing, rotation, mirroring), and real time compression using algorithms such as MPEG2 and JPEG. Also, technological demands in fields such as radar acquisition, manufacturing and remote guidance have led to the development of frame grabbers that can capture images at high frame rates and resolutions.

Analog frame grabbers, which accept and process analog video signals, include these circuits:

Digital frame grabbers, which accept and process digital video streams, include these circuits:

Circuitry common to both analog and digital frame grabbers:

Frame grabbers are used in medicine for many applications including telenursing and remote guidance. In situations where an expert at another location needs to be consulted, frame grabbers capture the image or video from the appropriate medical equipment so it can be sent digitally to the distant expert.

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