gimp - How do you describe the color characteristics of this gif palette and how do you change it?

Substrate by Jared Tarbell is a procedural art work in the Processing language that I'm discovering again. Here is a screenshot of the program's execution on my computer:

The program uses a .gif resource file for the colors(scaled up jpeg here):

I would like to know what this palette "is made of" in terms of color - a description? I would like to make my own palette and change the existing one to use with the program and would like to understand the original choice that was made here in that respect.

Answer

The original file is a gif file with 205 indexed colors so it seems there is some color repetition in the image(more than 205 squares).

Palette color description

From what I can understand of color theory(little), looking at the original file, the hue is mostly yellow/orange range (H40-60), or made from adjacent colors. Average to low chroma, with one average and one low saturation segment, and pretty much all high value colors. Less than 10 % of 205 colors in the index contain any cyan. There are a some few high hue, low value colors which are saturated for contrast. And a few reds. Overall some kind of (bright) pastel palette of golds, with a splash of "lime" looking shaded yellows, and some few darker elements for contrast. I think. But the layout of the resource image doesn't help in figuring it out.

convert file.gif -unique-colors -scale 1000% color_table.gif

Result:

ImageMagick is useful here to reconstruct an image made out only of unique colors and presented in the order of the color index(and the order can be sorted with hue and saturation in Gimp). It's also possible to extract a list of values for the colors and an average color value:

convert file.gif -unique-colors -depth 16 txt:  #output not shown
convert file.gif -resize 1x1 txt:
# ImageMagick pixel enumeration: 1,1,255,srgb
0,0: (214,195,152)  #D6C398  srgb(214,195,152)

Which is a slightly desaturated orange (see also); a tint of dark orange. Visually I had focused on the most striking color in the palette I think, some vivid yellow. But a bright pastel of that orange looks like that yellow. In any case using that average value with Adobe Color and looking at triadic and complementary colors helped me understand those darker/more saturated colors in the palette.

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Changing the palette

It's possible¹ to alter the indexed color space with Gimp in the Colors/Map menu (left: Rearrange manually or sort by hue or saturation, right: Set with the new palette colors):

So I ended up with this:

Which I could then use with the sketch to generate something like this:

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_{1. See the Gimp documentation about palettes and converting an image to indexed mode.}