Quartus - Need Helllppp BADLY, counters and other logic

Are you sure this is the way you want to down sample your image.

I can't imagine you will get a very good results.

A better way (More complex too I am affraid) Would be to perform some kind of filtering to determine the average the value of pixels in each 20x20 square.

If you continue with your scheme then you will need counters to count horizontal pixels (Reset from the line sync pulse) and couners to count the vertical pixels (Reset from the frame sync pulse)

You need to read up on VHDL (or verilog) design practices. Counters are a basic component of logic design and would should be able to find loads of info on the web.

Rgds