get contrast between two colors ( rgb )

contrast.py

from math import pow

def x(v):
    v /= 255
    
    res = v / 12.92 if v <= 0.03928 else pow( (v + 0.055) / 1.055, 2.4 )

    return res

def luminance(r, g, b):
    a = [x(v) for v in [r, g, b]]

    return a[0] * 0.2126 + a[1] * 0.7152 + a[2] * 0.0722

def get_contrast(rgb1, rgb2):
    lum1 = luminance(rgb1[0], rgb1[1], rgb1[2])
    lum2 = luminance(rgb2[0], rgb2[1], rgb2[2])
    brightest = max(lum1, lum2)
    darkest = min(lum1, lum2)
    return (brightest + 0.05) / (darkest + 0.05)