This is an NTSC colour bitmap created from the palette in ProSystem 1.3d source code :-
The colours in the ranges 0xA0 to 0xAF, 0xB0 to 0xBF and 0xC0 to 0xCF inclusive don't seem to have a nice change from dark to light. Colours 0xC6 and 0xC7 look very out of place to me.
As I recall, that guy who made this inputed the video from his 7800 into his PC and used the values from that to make this. This is the most accurate colors for the 7800 emulators. I suppose it could use a little more adjustments.