diff options
| -rw-r--r-- | src/colour.py | 83 |
1 files changed, 75 insertions, 8 deletions
diff --git a/src/colour.py b/src/colour.py index 92210ea..db51bc1 100644 --- a/src/colour.py +++ b/src/colour.py @@ -64,6 +64,21 @@ def ciexyz_to_ciexyy(X, Y, Z): return [x, y, Y] +def matrix_mul_vector(matrix, vector): + ''' + Multiplies a matrix with a vector + + @param matrix:list<list<int>> The matrix + @param vector:list<int> The vector + @return :list<int> The resulting vector + ''' + return [[r * v for r, v in zip(row, vector)] for row in matrix] + + +ciexyz_to_linear_matrix = [[ 3.240450, -1.537140, -0.4985320], + [-0.969266, 1.876010, 0.0415561], + [0.0556434, -0.204026, 1.0572300]] + def ciexyz_to_linear(X, Y, Z): ''' Convert CIE XYZ to [0, 1] linear RGB @@ -73,12 +88,13 @@ def ciexyz_to_linear(X, Y, Z): @param Z:float The Z parameter @return :[float, float, float] The red, green and blue components ''' - r = 3.24156 * X - 1.53767 * Y - 0.49870 * Z - g = -0.96920 * X + 1.87589 * Y + 0.04155 * Z - b = 0.05562 * X - 0.20396 * Y + 1.05686 * Z - return [r, g, b] + return matrix_mul_vector(ciexyz_to_linear_matrix, [X, Y, Z]) +linear_to_ciexyz_matrix = [[0.4124564, 0.3575761, 0.1804375], + [0.2126729, 0.7151522, 0.0721750], + [0.0193339, 0.1191920, 0.9503041]] + def linear_to_ciexyz(r, g, b): ''' Convert [0, 1] linear RGB to CIE XYZ @@ -88,10 +104,7 @@ def linear_to_ciexyz(r, g, b): @param b:float The blue component @return :[float, float, float] The X, Y and Z parameters ''' - X = 0.4123160 * r + 0.3576020 * g + 0.1805010 * b - Y = 0.2126000 * r + 0.7151990 * g + 0.0722016 * b - Z = 0.0193297 * r + 0.1192040 * g + 0.9506340 * b - return [X, Y, Z] + return matrix_mul_vector(linear_to_ciexyz_matrix, [r, g, b]) def srgb_to_ciexyy(r, g, b): @@ -125,3 +138,57 @@ def ciexyy_to_srgb(x, y, Y): rc = linear_to_standard(*rc) return rc + +def ciexyz_to_cielab(x, y, z): + ''' + Convert from CIE XYZ to CIE L*a*b* + + @param x:float The X parameter + @param y:float The Y parameter + @param z:float The Z parameter + @return :[float, float, float] The L*, a* and b* components + ''' + x /= 0.95047 + z /= 1.08883 + f = lambda c : c ** 1 / 3 if c > 0.00885642 else (7.78 + 703 / 99900) * c + 0.1379310 + l = 116 * f(Y) - 16 + a = 500 * (f(X) - f(Y)) + b = 200 * (f(Y) - f(Z)) + return (l, a, b) + + +def cielab_to_xiexyz(l, a, b): + ''' + Convert from CIE L*a*b* to CIE XYZ + + @param l:float The L* parameter + @param a:float The a* parameter + @param b:float The b* parameter + @return :[float, float, float] The X, Y and Z components + ''' + y = (l + 16) / 116 + x = a / 500 + y + z = y - b / 200 + f = lambda c : c ** 3 if c ** 3 > 0.00885642 else (c - 0.1379310) / (7.78 + 703 / 99900) + (x, y, z) = [f(c) for c in (x, y, z)] + x *= 0.95047 + y *= 1.08883 + return (x, y, z) + + +def delta_e(a, b): + ''' + Convert the distance (∆E*_ab) between two [0, 1] sRGB colours + + @param a:(float, float, float) The first colour + @param b:(float, float, float) The second colour + @return :float The difference + ''' + a = standard_to_linear(*a) + b = standard_to_linear(*b) + a = linear_to_ciexyz(*a) + b = linear_to_ciexyz(*b) + a = ciexyz_to_cielab(*a) + b = ciexyz_to_cielab(*b) + return sum([(c1 - c2) ** 2 for c1, c2 in zip(a, b)]) ** 0.5 + |