Created
November 29, 2023 02:56
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| const m1 = 0.1593017578125; | |
| const m2 = 78.84375; | |
| const c1 = 0.8359375; | |
| const c2 = 18.851525; | |
| const c3 = 18.6875; | |
| double inversePq(double n) { | |
| final top = max( | |
| pow(n, 1 / m2) - c1, | |
| 0, | |
| ); | |
| final bottom = c2 - c3 * pow(n, 1 / m2); | |
| final result = pow(top / bottom, 1 / m1).toDouble(); | |
| return result * 10000 / 203; | |
| } | |
| void applyInversePq(Float32List data) { | |
| for (var i = 0; i < data.length; i += 3) { | |
| data[i] = inversePq(data[i]); | |
| data[i + 1] = inversePq(data[i + 1]); | |
| data[i + 2] = inversePq(data[i + 2]); | |
| } | |
| } | |
| // srgb | |
| final srgbXyzMatrix = Matrix3( | |
| 0.4124564, | |
| 0.3575761, | |
| 0.1804375, | |
| 0.2126729, | |
| 0.7151522, | |
| 0.0721750, | |
| 0.0193339, | |
| 0.1191920, | |
| 0.9503041, | |
| ); | |
| // prophoto rgb | |
| final prophotoRgbToXyzMatrix = Matrix3( | |
| 0.7976749, | |
| 0.1351917, | |
| 0.0313534, | |
| 0.2880402, | |
| 0.7118741, | |
| 0.0000857, | |
| 0.0000000, | |
| 0.0000000, | |
| 0.8252100, | |
| ); | |
| Matrix3 get rgbToXyzMatrix => prophotoRgbToXyzMatrix.clone(); | |
| Matrix3 get inverseRgbToXyzMatrix => prophotoRgbToXyzMatrix.clone()..invert(); | |
| Vector3 rgbToXyz(Vector3 rgb) { | |
| return rgbToXyzMatrix.clone() * rgb; | |
| } | |
| Vector3 xyzToRgb(Vector3 xyz) { | |
| return inverseRgbToXyzMatrix.clone() * xyz; | |
| } | |
| Vector3 XYZ_to_xyY(Vector3 XYZ) { | |
| double X = XYZ.x; | |
| double Y = XYZ.y; | |
| double Z = XYZ.z; | |
| double divisor = X + Y + Z; | |
| if (divisor == 0.0) divisor = 1e-6; | |
| double x = X / divisor; | |
| double y = Y / divisor; | |
| return Vector3(x, y, Y); | |
| } | |
| Vector3 xyY_to_XYZ(Vector3 xyY) { | |
| double x = xyY.x; | |
| double y = xyY.y; | |
| double Y = xyY.z; | |
| double multiplo = Y / max(y, 1e-6); | |
| double z = 1.0 - x - y; | |
| double X = x * multiplo; | |
| double Z = z * multiplo; | |
| return Vector3(X, Y, Z); | |
| } | |
| const double ip = 0.58535; // linear length | |
| const double k1 = 0.83802; // linear strength | |
| const double k3 = 0.74204; // shoulder strength | |
| double f2(double Y, double k1, double k3, double ip) { | |
| ip /= k1; | |
| double k2 = (k1 * ip) * (1.0 - k3); | |
| double k4 = (k1 * ip) - (k2 * log(1.0 - k3)); | |
| return Y < ip ? Y * k1 : log((Y / ip) - k3) * k2 + k4; | |
| } | |
| double tonemapping(double x) { | |
| const double over_white = 1019.0 / 940.0; // 109% range (super-whites) | |
| return f2(x, k1, k3, ip) / over_white; | |
| } | |
| double gamma2_2(double value) { | |
| return value > 0 ? pow(value, 2.2).toDouble() : 0; | |
| } | |
| void applyGamma(Float32List data) { | |
| for (var i = 0; i < data.length; i += 3) { | |
| data[i] = gamma2_2(data[i]); | |
| data[i + 1] = gamma2_2(data[i + 1]); | |
| data[i + 2] = gamma2_2(data[i + 2]); | |
| } | |
| } | |
| void applyHdrToSdrTonemap(Float32List data) { | |
| applyInversePq(data); | |
| for (var i = 0; i < data.length; i += 3) { | |
| final r = data[i]; | |
| final g = data[i + 1]; | |
| final b = data[i + 2]; | |
| var color = Vector3(r, g, b); | |
| color = rgbToXyz(color); | |
| color = XYZ_to_xyY(color); | |
| color = Vector3(color.x, color.y, tonemapping(color.z)); | |
| color = xyY_to_XYZ(color); | |
| color = xyzToRgb(color); | |
| data[i] = color.x; | |
| data[i + 1] = color.y; | |
| data[i + 2] = color.z; | |
| } | |
| applyGamma(data); | |
| } |
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