This is true for proper standards-compliant NTSC signals, but a comb filter won't help you for CGA since the CGA card generates an integer number of color carri

This is true for proper standards-compliant NTSC signals, but a comb filter won't help you for CGA since the CGA card generates an integer number of color carrier cycles per scanline (228, not 227.5). So the phase isn't reversed each line and there's no way to get any extra detail.