There is not much to say about hardware, as nearly everything is
under software control.
Composite video signal, typically from the low-cost "cube" TV
camera, is fed directly to the 8-bit ADC. The input voltage range
for ADC1173 is 0-2V and, as one pixel of video data contains 6
pixels, there is no need to amplify the signal. The first half of
dual comparator LM393 serves as sync detector, and the other half is
for automatic analog level conditioning. There is also the video
amplifier MAX4012, if the video out is needed.
VGA video out is not necessarry during operation, but it is very
usefuul in development and adjustment process. Bits 0-5 are fed
directly to the resistor ladder, and bits 6 and 7 are binary blue
and red signals, respectively. As bits 6 and 7 are intensively used
in picture processing, mainly for component selecting and grouping,
this concept is very helpful during development, and yet simple.