How To Reduce Image Palette To Specific Colors?

I am playing with a program in Python to create cross stitch schemes and need to reduce colors in an image to specific floss colors like this. Not necessary to use all the colors f

Solution 1:

Here is an example of memoize. I've also used the builtin min

def nearest(pixel_color, mem={}):
    if pixel_color in mem:
        return mem[pixel_color]
    n = min(floss_palette, key=lambda fc:delta_e_cie2000(pixel_color, fc))
    mem[pixel_color] = n
    return mem[pixel_color]

result = [nearest(pixel_color) for pixel_color in image]