A frame grabber is an electronic device that captures 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 in raw or compressed digital form. Historically frame grabbers were the predominant way to interface cameras to PC's. This has substantially changed in recent years as direct camera connections via USB, Ethernet and IEEE 1394 ("FireWire") interfaces have become practical and prevalent. Menzel deal with following Principal of Frame Grabber Card. Bit Flow. Imaging Sources.