A c64 pal comparison. My green is the same, and the blue was just changed a tad.
I noticed I have some of the palette histogram project pics online, so here they are. I had to compress pretty hard to save bandwidth/space.
256 source pics, I just googled various things, took the decent pics and scaled down with nearest neighbour. (fullsize is 1024)
Here's a HSV cylinder plot, 16 slices (meaning I had to compress the plot to 16 values). Distance from the center is saturation.. I think I plotted random colors to make the color part, i.e. the colors you see are the RGB 3D Cube existing in a HSV cylinder dimension! You can see the histogram being rather diagonal.
If you wonder why the high value (white) tip is skew, it's because some hues are darker. Yellow kind of goes off like a wedge there cuz it's brighter.
1/4th of my source was pron... because 1/4th of the internet is. Lots of skin tones here...
RGB cube. I plotted /4 here to make 64 pixel squares, but here I scaled down further. It's just to give you an idea what the cube is about.
Finally, my 16 color palette. I faded the spectrum and added the histogram as reference. Hard jpg compression, sorry.
As you can see I dare venture out a bit outside the safe/popular colors just to get some range. If I were to pick the most popular colors only, I'd end up with 16 greys. Again note that is is /4 to make a 64 pix cube so there has been some compression.
C64 palette. Note thatthe black and white are in the corners.
I once tried to make a 64 color palette based on this data, but I never arrived at anything conclusive.