VGA input format

Question

How could you get coordinates (x,y) of pixel colors in VGA format (from a vga cable)? I know pins 13 and 14 are horizontal & vertical sync, so how would I use that to get the coordinates of the rgb obtained from the first 3 pins?

Answer 1

VGA, as per DE-15 and similar output channels is analog¹.

There is no trivial way to "read" a pixel at a specific coordinate - when going directly to an analog CRT there weren't even "x/y pixel coordinates" assigned by the device! It was only with the advent of later LCD monitors that the VGA analog signal was converted back into a digital (i.e. "with coordinates") format prior to being displayed.

One way to solve this problem/task is to use an analog frame grabber card/device and access the digitized image stream.

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¹ See VGA Video Signal Format and Timing Specifications for a brief overview of the analog format.