I think you are confused what these cameras do.
The Blackfin, CMUcam (not CMU), etc. are cameras combined with built-in image processing. You command it to process what you want to know, it does it, then tells you the result.
All cameras process only one frame. But if you record the result after each frame, you then can generate a frame by frame comparison in your own software.
The datasheets for each of these cameras tell you what input commands and output data you will get.
Roborealm generally works in the same way, but uses your computer instead of a built-in dedicated chip on the camera itself.