256-256-256 RGB HEX => it's-your-choice RGB => 256-256-256 RGB HEX. Used to convert some 256-256-256 colors to 8-8-4.

color_converter.py

def tuple_to_hex(tup):
    return "".join(map(
        lambda n: hex(n)[2:].zfill(2),
        tup
    ))


def hex_to_tuple(h):
    return tuple(int(h[i:i+2], 16) for i in range(0, 6, 2))


def minimize(color, depth):
    return (
        round(color / round(256 / (depth - 1)))
        * 255 // (depth - 1)
    )


def conv(color_tup, depths):
    return tuple(
        minimize(color, depth)
        for color, depth
        in zip(color_tup, depths)
    )


depths = tuple(map(
    lambda num: int(num.strip()),
    input("depths: ").split(",")
))
while True:
    print(tuple_to_hex(conv(hex_to_tuple(input()), depths)))