Calculate the color temperature CCT from web color hex triplets (Python)

01-atomus_riser_pipe_color.py

#!/usr/bin/env python3

import struct
import warnings

import colour
import numpy as np


measured_colours = ["#E42024",
                    "#E11E22",
                    "#E52125",
                    "#E51E21",
                    "#D71D1E"]

# NOTE: The fake scaling factor is BS,
# but helps with colours far from the black-body curve
fake_scaling_factor = 100

def hex2rgb(hex):
    # https://stackoverflow.com/a/4296263
    rgb_tuple = struct.unpack('BBB', bytes.fromhex(hex[1:]))
    return np.array(rgb_tuple)

def rgb_frac2cct(rgb_frac):
    # https://stackoverflow.com/a/38889696
    xyz = colour.sRGB_to_XYZ(rgb_frac)
    xy = colour.XYZ_to_xy(xyz)
    return colour.xy_to_CCT(xy, 'hernandez1999')


if __name__ == "__main__":
    temperatures = []
    for color_str in measured_colours:
        rgb = hex2rgb(color_str)
        rgb_frac = rgb / 255 / fake_scaling_factor
        cct = rgb_frac2cct(rgb_frac)
        temperatures.append(cct)
        # print('{}\t{}\t{:.1f}'.format(rgb, rgb_frac, cct))

    print('{:.0f} +- {:.0f} K'.format(np.mean(temperatures),
                                      np.std(temperatures) / np.sqrt(np.std(temperatures))))

# Output: 1074 +- 7 K

requirements.txt

colour-science~=0.3.15
numpy~=1.18.2