From bd6427412a85741be7ef7846bae228c79cbfcb22 Mon Sep 17 00:00:00 2001 From: Mattias Andrée Date: Thu, 13 Feb 2014 03:56:43 +0100 Subject: colour temperature MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Signed-off-by: Mattias Andrée --- src/colour.py | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 56 insertions(+) create mode 100644 src/colour.py (limited to 'src/colour.py') diff --git a/src/colour.py b/src/colour.py new file mode 100644 index 0000000..df5b38d --- /dev/null +++ b/src/colour.py @@ -0,0 +1,56 @@ +#!/usr/bin/env python3 + +# Copyright © 2014 Mattias Andrée (maandree@member.fsf.org) +# +# This program is free software: you can redistribute it and/or modify +# it under the terms of the GNU Affero General Public License as published by +# the Free Software Foundation, either version 3 of the License, or +# (at your option) any later version. +# +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU Affero General Public License for more details. +# +# You should have received a copy of the GNU Affero General Public License +# along with this program. If not, see . + + +def linear_to_standard(*colour): + return [12.92 * c if c <= 0.0031308 else (1 + 0.055) * c ** (1 / 2.4) - 0.055 for c in colour] + +def standard_to_linear(*colour): + return [c / 12.92 if c <= 0.04045 else ((c + 0.055) / (1 + 0.055)) ** 2.4 for c in colour] + +def ciexyy_to_ciexyz(x, y, Y): + return [Y * x / y, Y, Y * (1 - x - y) / y] + +def ciexyz_to_ciexyy(X, Y, Z): + p = -Y / X + q = 1 + Y / X + y = 1 / (p / 2 + (p ** 2 / 4 - q) ** 0.5) + x = X * y / Y + return [x, y, Y] + +def ciexyz_to_linear(X, Y, Z): + r = 3.2406 * X - 1.5372 * Y - 0.4986 * Z + g = -0.9689 * X + 1.8758 * Y + 0.0415 * Z + b = 0.0557 * X - 0.2040 * Y + 1.0570 * Z + return [r, g, b] + +def linear_to_ciexyz(r, g, b): + X = 0.4124 * r + 0.3576 * g + 0.1805 * b + Y = 0.2126 * r + 0.7152 * g + 0.0722 * b + Z = 0.0193 * r + 0.1192 * g + 1.9502 * b + return [X, Y, Z] + +def to_ciexyy(r, g, b): + (r, g, b) = standard_to_linear(r, g, b) + (X, Y, Z) = linear_to_ciexyz(r, g, b) + return ciexyz_to_ciexyy(X, Y, Z) + +def to_srgb(x, y, Y): + (X, Y, Z) = ciexyy_to_ciexyz(x, y, Y) + (r, g, b) = ciexyz_to_linear(X, Y, Z) + return linear_to_standard(r, g, b) + -- cgit v1.2.3-70-g09d2