Another BYTE Circuit Cellar Project. I bought the HW already assembled. It was just to connect it to a video camera and a serial receiving device (a PC in my case) and it was possible to do a 64 shade gray scale digitizing and send the image off the serial port. The most work was exploring the video modes of the VGA card I used to display the image.
As already mentioned, I am not a big fan of analog electronics, and this digitizer boards had a small, but (for me) complicated analog section which received and "disassembled" the video signal. The heart of the digital section was an Intel 8031 CPU, the EPROM holding the software, two SRAM chips and some support cicuitry. So I did not dive into the boards inner working, but into graphic modes and the representation of graphic data.
To get a first grip on video (i.e. graphics) data, I wrote some programs to read/write graphic files (.BMP). This allowed me to learn about the internals of these file formats and how to manipulate them.
The PC display boards I owned at that time was an EGA and a VGA, which could operate in various display modes. It was interesting to learn about the graphic board memory layout used with the various graphic modes.
More Info: Ciarcia's Circuit Cellar, Volume 7