slang-shaders/misc/colorimetry.slang

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#version 450
/*
Colorimetry shader
Ported from Drag's NES Palette Generator
http://drag.wootest.net/misc/palgen.html
*/
layout(std140, set = 0, binding = 0) uniform UBO
{
mat4 MVP;
vec4 OutputSize;
vec4 OriginalSize;
vec4 SourceSize;
uint FrameCount;
} global;
layout(push_constant) uniform Push
{
float color_mode;
float white_point_d93;
float clipping_method;
} params;
#pragma parameter color_mode "Colorimetry mode" 0.0 0.0 2.0 1.0
#pragma parameter white_point_d93 "Use D93 white point" 1.0 0.0 1.0 1.0
#pragma parameter clipping_method "Color clipping method" 0.0 0.0 2.0 1.0
#define color_mode params.color_mode
#define white_point_d93 params.white_point_d93
#define clipping_method params.clipping_method
vec3 huePreserveClipDarken(float r, float g, float b)
{
float ratio = 1.0;
if ((r > 1.0) || (g > 1.0) || (b > 1.0))
{
float max = r;
if (g > max)
max = g;
if (b > max)
max = b;
ratio = 1.0 / max;
}
r *= ratio;
g *= ratio;
b *= ratio;
r = clamp(r, 0.0, 1.0);
g = clamp(g, 0.0, 1.0);
b = clamp(b, 0.0, 1.0);
return vec3(r, g, b);
}
vec3 huePreserveClipDesaturate(float r, float g, float b)
{
float l = (.299 * r) + (0.587 * g) + (0.114 * b);
bool ovr = false;
float ratio = 1.0;
if ((r > 1.0) || (g > 1.0) || (b > 1.0))
{
ovr = true;
float max = r;
if (g > max) max = g;
if (b > max) max = b;
ratio = 1.0 / max;
}
if (ovr)
{
r -= 1.0;
g -= 1.0;
b -= 1.0;
r *= ratio;
g *= ratio;
b *= ratio;
r += 1.0;
g += 1.0;
b += 1.0;
}
r = clamp(r, 0.0, 1.0);
g = clamp(g, 0.0, 1.0);
b = clamp(b, 0.0, 1.0);
return vec3(r, g, b);
}
vec3 ApplyColorimetry(vec3 color)
{
//http://www.brucelindbloom.com/Eqn_RGB_XYZ_Matrix.html
//http://www.dr-lex.be/random/matrix_inv.html
// Convert the (x,y) values to X Y Z.
float R = color.r;
float G = color.g;
float B = color.b;
float Rx = 0.0;
float Ry = 0.0;
float Gx = 0.0;
float Gy = 0.0;
float Bx = 0.0;
float By = 0.0;
float Wx = 0.0;
float Wy = 0.0;
if (white_point_d93 > 0.5)
{
Wx = 0.31;
Wy = 0.316;
}
else
{
Wx = 0.3127;
Wy = 0.329;
}
if (color_mode < 0.5)
{
// FCC 1953
// Original FCC standard for the color of the phosphors
Rx = 0.67;
Ry = 0.33;
Gx = 0.21;
Gy = 0.71;
Bx = 0.14;
By = 0.08;
}
else if (color_mode == 1.0)
{
// SMPTE C (1987)
// A newer standard for the color of the phospors. (Not used in Japan)
Rx = 0.63;
Ry = 0.34;
Gx = 0.31;
Gy = 0.595;
Bx = 0.155;
By = 0.07;
}
else
{
//sRGB (PC Monitors)
//The colorimetry used in PC monitors, like the one you're (probably) looking at right now.
Rx = 0.64;
Ry = 0.33;
Gx = 0.3;
Gy = 0.6;
Bx = 0.15;
By = 0.06;
}
float Xr = Rx / Ry;
float Xg = Gx / Gy;
float Xb = Bx / By;
float Xw = Wx / Wy;
float Yr = 1.0;
float Yg = 1.0;
float Yb = 1.0;
float Yw = 1.0;
float Zr = (1.0 - Rx - Ry) / Ry;
float Zg = (1.0 - Gx - Gy) / Gy;
float Zb = (1.0 - Bx - By) / By;
float Zw = (1.0 - Wx - Wy) / Wy;
// Get ready for a bunch of painful math. I need to invert a matrix, then multiply it by a vector.
// Determinant for inverse matrix
float sDet = (Xr*((Zb*Yg)-(Zg*Yb)))-(Yr*((Zb*Xg)-(Zg*Xb)))+(Zr*((Yb*Xg)-(Yg*Xb)));
float Sr = ((((Zb*Yg)-(Zg*Yb))/sDet)*Xw) + ((-((Zb*Xg)-(Zg*Xb))/sDet)*Yw) + ((((Yb*Xg)-(Yg*Xb))/sDet)*Zw);
float Sg = ((-((Zb*Yr)-(Zr*Yb))/sDet)*Xw) + ((((Zb*Xr)-(Zr*Xb))/sDet)*Yw) + ((-((Yb*Xr)-(Yr*Xb))/sDet)*Zw);
float Sb = ((((Zg*Yr)-(Zr*Yg))/sDet)*Xw) + ((-((Zg*Xr)-(Zr*Xg))/sDet)*Yw) + ((((Yg*Xr)-(Yr*Xg))/sDet)*Zw);
// This should be the completed RGB -> XYZ matrix.
// Multiply each of the first three members by R, then add them together to get X
float convMatrix[9] = float[] (0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0);
convMatrix[0] = Sr*Xr;
convMatrix[1] = Sg*Xg;
convMatrix[2] = Sb*Xb;
convMatrix[3] = Sr*Yr;
convMatrix[4] = Sg*Yg;
convMatrix[5] = Sb*Yb;
convMatrix[6] = Sr*Zr;
convMatrix[7] = Sg*Zg;
convMatrix[8] = Sb*Zb;
// Convert RGB to XYZ using the matrix generated with the specified RGB and W points.
float X = (convMatrix[0] * R) + (convMatrix[1] * G) + (convMatrix[2] * B);
float Y = (convMatrix[3] * R) + (convMatrix[4] * G) + (convMatrix[5] * B);
float Z = (convMatrix[6] * R) + (convMatrix[7] * G) + (convMatrix[8] * B);
// This is the conversion matrix for CIEXYZ -> sRGB. I nicked this from:
// http://www.brucelindbloom.com/Eqn_RGB_XYZ_Matrix.html
// and I know it's right because when you use the sRGB colorimetry, this matrix produces identical results to
// just using the raw R, G, and B above.
float xyztorgb[9] = float[] (3.2404, -1.5371, -0.4985, -0.9693, 1.876, 0.0416, 0.0556, -0.204, 1.0572);
// Convert back to RGB using the XYZ->sRGB matrix.
R = (xyztorgb[0]*X) + (xyztorgb[1]*Y) + (xyztorgb[2]*Z);
G = (xyztorgb[3]*X) + (xyztorgb[4]*Y) + (xyztorgb[5]*Z);
B = (xyztorgb[6]*X) + (xyztorgb[7]*Y) + (xyztorgb[8]*Z);
vec3 corrected_rgb;
// Apply desired clipping method to out-of-gamut colors.
if (clipping_method < 0.5)
{
//If a channel is out of range (> 1.0), it's simply clamped to 1.0. This may change hue, saturation, and/or lightness.
R = clamp(R, 0.0, 1.0);
G = clamp(G, 0.0, 1.0);
B = clamp(B, 0.0, 1.0);
corrected_rgb = vec3(R, G, B);
}
else if (clipping_method == 1.0)
{
//If any channels are out of range, the color is darkened until it is completely in range.
corrected_rgb = huePreserveClipDarken(R, G, B);
}
else if (clipping_method == 2.0)
{
//If any channels are out of range, the color is desaturated towards the luminance it would've had.
corrected_rgb = huePreserveClipDesaturate(R, G, B);
}
return corrected_rgb;
}
#pragma stage vertex
layout(location = 0) in vec4 Position;
layout(location = 1) in vec2 TexCoord;
layout(location = 0) out vec2 vTexCoord;
void main()
{
gl_Position = global.MVP * Position;
vTexCoord = TexCoord;
}
#pragma stage fragment
layout(location = 0) in vec2 vTexCoord;
layout(location = 0) out vec4 FragColor;
layout(set = 0, binding = 2) uniform sampler2D Source;
void main()
{
vec4 c = texture(Source, vTexCoord.xy);
vec3 rgb = vec3(c.r, c.g, c.b);
vec3 out_color = ApplyColorimetry(rgb);
FragColor = vec4(out_color, 1.0);
}