A frame grabber is a device that accepts standard video signals and digitizes the current video frame into a single, bitmapped still image. Frame grabbers can be stand-alone devices that plug into a port on the computer or a function built into the video capture board or display adapter.  

Digital

Digital frame grabbers interface directly to digital cameras and therefore do not have to convert the data.

Analog

Analog frame grabbers are devices that capture and convert analog video signals into digital data.