Works out the YIQ values of a given RGB colour and suggests a pallet of similar colours with the same chrominance. This can be used on legacy TV platforms to reduce chroma crawl, where colours bleed into each other.

yiq-color-balance.py

#!/usr/bin/env python

import sys

def rgb2Yiq(red, green, blue):
	y = int((0.299 * red) + (0.587 * green) + (0.114 * blue))
	i = int((0.596 * red) - (0.275 * green) - (0.321 * blue))
	q = int((0.212 * red) - (0.528 * green) + (0.311 * blue))
	return (y, i, q)

def constrain(n):
	if n < 0:
		return 0
	elif n > 255:
		return 255
	else:
		return n

def yiq2Rgb(y, i, q):
	r = int(y + (0.956 * i) + (0.620 * q))
	g = int(y - (0.272 * i)  - (0.647 * q))
	b = int(y  - (1.108 * i) + (1.705 * q))
	return (constrain(r), constrain(g), constrain(b))

def rgb2Hex(red, green, blue):
	return "#{:02X}{:02X}{:02X}".format(red, green, blue)

def printPalette(change, y, i, q):
	(r, g, b) = yiq2Rgb(y, i, q)
	print "{}% YIQ: ( {}  {}  {} ) => RGB: ( {}  {}  {} ) | {}".format(change, y, i, q, r, g, b, rgb2Hex(r, g, b))

def main(args):
	r = int(args[1])
	g = int(args[2])
	b = int(args[3])
	(y, i, q) = rgb2Yiq(r, g, b)
	(r2,g2,b2) = yiq2Rgb(y, i, q)
	
	print "RGB: ( {}  {}  {} ) => YIQ: ( {}  {}  {} ) => RGB: ( {}  {}  {} )".format(r, g, b, y, i, q, r2, g2, b2)
	printPalette(27, int(0.27 * 255), i, q)
	printPalette(33, int(0.33 * 255), i, q)
	printPalette(45, int(0.45 * 255), i, q)
	printPalette(69, int(0.69 * 255), i, q)
	printPalette(82, int(0.82 * 255), i, q)


if __name__ == '__main__':
	if len(sys.argv) < 4:
		print "usage: ", sys.argv[0], "RED BLUE GREEN"
		print "    RED, BLUE and GREEN are integers"
	else:
		main(sys.argv)