Hi, this is great as I wanted some fixed palettes for some cartoon image processing in a test project, and wasn't aware of those pastel palettes but there is a little room for improvement on the colour distance algorithm used in quantisation.

The algorithm you've used is a Euclidean sum of components https://github.com/Schrodinger-Hat/ImageGoNord-pip/blob/mast... You may (human perception!) find better colour accuracy in using the Compuphase algorithm https://www.compuphase.com/cmetric.htm or possibly a luminance or other cielab approach.

The implementation of the former is not much more difficult, e.g. see the C version breakout box on that link, but you should find (at least for my projects where I've used it) colour quantisation is (subjectively!) substantially better.