slang-shaders/misc/colorspace-tools.h

// Colorspace Tools
// ported from Asmodean's PsxFX Shader Suite v2.00
// NTSC color code from SimoneT
// Jzazbz code from torridgristle
// License: GPL v2+

/*------------------------------------------------------------------------------
                       [GAMMA CORRECTION CODE SECTION]
------------------------------------------------------------------------------*/

vec3 EncodeGamma(vec3 color, float gamma)
{
    color = clamp(color, 0.0, 1.0);
    color.r = (color.r <= 0.0404482362771082) ?
    color.r / 12.92 : pow((color.r + 0.055) / 1.055, gamma);
    color.g = (color.g <= 0.0404482362771082) ?
    color.g / 12.92 : pow((color.g + 0.055) / 1.055, gamma);
    color.b = (color.b <= 0.0404482362771082) ?
    color.b / 12.92 : pow((color.b + 0.055) / 1.055, gamma);

    return color;
}

vec3 DecodeGamma(vec3 color, float gamma)
{
    color = clamp(color, 0.0, 1.0);
    color.r = (color.r <= 0.00313066844250063) ?
    color.r * 12.92 : 1.055 * pow(color.r, 1.0 / gamma) - 0.055;
    color.g = (color.g <= 0.00313066844250063) ?
    color.g * 12.92 : 1.055 * pow(color.g, 1.0 / gamma) - 0.055;
    color.b = (color.b <= 0.00313066844250063) ?
    color.b * 12.92 : 1.055 * pow(color.b, 1.0 / gamma) - 0.055;

    return color;
}

#ifdef GAMMA_CORRECTION
vec4 GammaPass(vec4 color, vec2 texcoord)
{
    const float GammaConst = 2.233333;
    color.rgb = EncodeGamma(color.rgb, GammaConst);
    color.rgb = DecodeGamma(color.rgb, float(Gamma));

    return color;
}
#endif

// more gamma linearization algos
vec3 linear_srgb(vec3 x) {
#ifdef GAMMA_CORRECT
// use slower, more accurate calculation
    return mix(1.055*pow(x, vec3(1./2.4)) - 0.055, 12.92*x, step(x,vec3(0.0031308)));
#else
// use faster, less accurate calculation
    return pow(x,vec3(1.0/2.2));
#endif
}
 
vec3 srgb_linear(vec3 x) {
#ifdef GAMMA_CORRECT
    return mix(pow((x + 0.055)/1.055,vec3(2.4)), x / 12.92, step(x,vec3(0.04045)));
#else
    return pow(x,vec3(2.2));
#endif
}

vec3 linear_to_sRGB(vec3 color, float gamma){

    color = clamp(color, 0.0, 1.0);
    color.r = (color.r <= 0.00313066844250063) ?
    color.r * 12.92 : 1.055 * pow(color.r, 1.0 / gamma) - 0.055;
    color.g = (color.g <= 0.00313066844250063) ?
    color.g * 12.92 : 1.055 * pow(color.g, 1.0 / gamma) - 0.055;
    color.b = (color.b <= 0.00313066844250063) ?
    color.b * 12.92 : 1.055 * pow(color.b, 1.0 / gamma) - 0.055;

    return color.rgb;
}

vec3 sRGB_to_linear(vec3 color, float gamma){

    color = clamp(color, 0.0, 1.0);
    color.r = (color.r <= 0.04045) ?
    color.r / 12.92 : pow((color.r + 0.055) / (1.055), gamma);
    color.g = (color.g <= 0.04045) ?
    color.g / 12.92 : pow((color.g + 0.055) / (1.055), gamma);
    color.b = (color.b <= 0.04045) ?
    color.b / 12.92 : pow((color.b + 0.055) / (1.055), gamma);

    return color.rgb;
}

//Conversion matrices
vec3 RGBtoXYZ(vec3 RGB)
  {
      const mat3x3 m = mat3x3(
      0.6068909, 0.1735011, 0.2003480,
      0.2989164, 0.5865990, 0.1144845,
      0.0000000, 0.0660957, 1.1162243);
  
    return RGB * m;
  }
  
vec3 XYZtoRGB(vec3 XYZ)
  {
      const mat3x3 m = mat3x3(
      1.9099961, -0.5324542, -0.2882091,
     -0.9846663,  1.9991710, -0.0283082,
      0.0583056, -0.1183781,  0.8975535);
  
    return XYZ * m;
}

vec3 XYZtoSRGB(vec3 XYZ)
{
    const mat3x3 m = mat3x3(
    3.2404542,-1.5371385,-0.4985314,
   -0.9692660, 1.8760108, 0.0415560,
    0.0556434,-0.2040259, 1.0572252);

    return XYZ * m;
  }
  
vec3 RGBtoYUV(vec3 RGB)
 {
     const mat3x3 m = mat3x3(
     0.2126, 0.7152, 0.0722,
    -0.09991,-0.33609, 0.436,
     0.615, -0.55861, -0.05639);
 
     return RGB * m;
 }
 
vec3 YUVtoRGB(vec3 YUV)
 {
     const mat3x3 m = mat3x3(
     1.000, 0.000, 1.28033,
     1.000,-0.21482,-0.38059,
     1.000, 2.12798, 0.000);
 
      return YUV * m;
  }

vec3 RGBtoYIQ(vec3 RGB)
  {
     const mat3x3 m = mat3x3(
     0.2989, 0.5870, 0.1140,
     0.5959, -0.2744, -0.3216,
     0.2115, -0.5229, 0.3114);
     return RGB * m;
  }

vec3 YIQtoRGB(vec3 YIQ)
  {
     const mat3x3 m = mat3x3(
     1.0, 0.956, 0.6210,
     1.0, -0.2720, -0.6474,
     1.0, -1.1060, 1.7046);
   return YIQ * m;
  }
  
vec3 XYZtoYxy(vec3 XYZ)
  {
    float w = (XYZ.r + XYZ.g + XYZ.b);
      vec3 Yxy;
    Yxy.r = XYZ.g;
    Yxy.g = XYZ.r / w;
    Yxy.b = XYZ.g / w;
  
      return Yxy;
  }
  
vec3 YxytoXYZ(vec3 Yxy)
  {
    vec3 XYZ;
    XYZ.g = Yxy.r;
    XYZ.r = Yxy.r * Yxy.g / Yxy.b;
    XYZ.b = Yxy.r * (1.0 - Yxy.g - Yxy.b) / Yxy.b;
  
    return XYZ;
  }
  
// RGB <-> CMYK conversions require 4 channels
vec4 RGBtoCMYK(vec3 RGB){
	float Red     = RGB.r;
	float Green   = RGB.g;
	float Blue    = RGB.b;
	float Black   = min(1.0 - Red, min(1.0 - Green, 1.0 - Blue));
	float Cyan    =    (1.0 - Red   - Black) / (1.0 - Black);
	float Magenta =    (1.0 - Green - Black) / (1.0 - Black);
	float Yellow  =    (1.0 - Blue  - Black) / (1.0 - Black);
	return vec4(Cyan, Magenta, Yellow, Black);
}
 
vec3 CMYKtoRGB(vec4 CMYK){
	float Cyan    = CMYK.x;
	float Magenta = CMYK.y;
	float Yellow  = CMYK.z;
	float Black   = CMYK.w;
	float Red     = 1.0 - min(1.0, Cyan    * (1.0 - Black) + Black);
	float Green   = 1.0 - min(1.0, Magenta * (1.0 - Black) + Black);
	float Blue    = 1.0 - min(1.0, Yellow  * (1.0 - Black) + Black);
	return vec3(Red, Green, Blue);
}
  
// Converting pure hue to RGB
vec3 HUEtoRGB(float H)
{
    float R = abs(H * 6.0 - 3.0) - 1.0;
    float G = 2.0 - abs(H * 6.0 - 2.0);
    float B = 2.0 - abs(H * 6.0 - 4.0);

    return clamp(vec3(R, G, B), 0.0, 1.0);
}

// Converting RGB to hue/chroma/value
vec3 RGBtoHCV(vec3 RGB)
{
    vec4 BG = vec4(RGB.bg,-1.0, 2.0 / 3.0);
    vec4 GB = vec4(RGB.gb, 0.0,-1.0 / 3.0);

    vec4 P = (RGB.g < RGB.b) ? BG : GB;

    vec4 XY = vec4(P.xyw, RGB.r);
    vec4 YZ = vec4(RGB.r, P.yzx);

    vec4 Q = (RGB.r < P.x) ? XY : YZ;

    float C = Q.x - min(Q.w, Q.y);
    float H = abs((Q.w - Q.y) / (6.0 * C + 1e-10) + Q.z);

    return vec3(H, C, Q.x);
}
  
vec3 RGBtoHSV(vec3 c)
{
    vec4 K = vec4(0.0, -1.0 / 3.0, 2.0 / 3.0, -1.0);
    vec4 p = c.g < c.b ? vec4(c.bg, K.wz) : vec4(c.gb, K.xy);
    vec4 q = c.r < p.x ? vec4(p.xyw, c.r) : vec4(c.r, p.yzx);

    float d = q.x - min(q.w, q.y);
    float e = 1.0e-10;
    return vec3(abs(q.z + (q.w - q.y) / (6.0 * d + e)), d / (q.x + e), q.x);
}

vec3 HSVtoRGB(vec3 c)
{
    vec4 K = vec4(1.0, 2.0 / 3.0, 1.0 / 3.0, 3.0);
    vec3 p = abs(fract(c.xxx + K.xyz) * 6.0 - K.www);
    return c.z * mix(K.xxx, clamp(p - K.xxx, 0.0, 1.0), c.y);
}

// conversion from NTSC RGB Reference White D65 ( color space used by NA/Japan TV's ) to XYZ
vec3 NTSC(vec3 c)
 {
     vec3 v = vec3(pow(c.r, 2.2), pow(c.g, 2.2), pow(c.b, 2.2)); //Inverse Companding
     return RGBtoXYZ(v);
 }
 
// conversion from XYZ to sRGB Reference White D65 ( color space used by windows ) 
vec3 sRGB(vec3 c)
 {
     vec3 v = XYZtoSRGB(c);
     v = DecodeGamma(v, 2.4); //Companding
 
     return v;
 }
 
// NTSC RGB to sRGB
vec3 NTSCtoSRGB( vec3 c )
 { 
     return sRGB(NTSC( c )); 
 }

const float Pi = 3.1415926535897932384626433832795;
 
//  ---  Reference White Values  ---  //{
       
const vec3 D50 = vec3(0.9642, 1.0000, 0.8251);
const vec3 D55 = vec3(0.9568, 1.0000, 0.9214);
const vec3 D65 = vec3(0.9504, 1.0000, 1.0888);
    //D9000 apparently isn't a real standard so here's the CCT daylight calculation result
const vec3 D9000 = vec3(0.9520, 1.0000, 1.3661);
    //D9300 apparently isn't a real standard so here's the CCT daylight calculation result
const vec3 D9300 = vec3(0.95271,1.00000,1.39177);
        //Various CRT monitors, Duv describes distance from the blackbody curve. The smaller it is, the closer to "white" it is. +/- 0.006 is recommended by ANSI and EnergyStar.
    //NEC Multisync C400, claims 9300K but it isn't
const vec3 D9000NEC = vec3(0.88889,1.00000,1.28571);//8890K, 0.0139 Duv
    //KDS VS19
const vec3 D9000KDS = vec3(0.90354,1.00000,1.31190);//8939K, 0.0114 Duv
//}
 
//  ---  sRGB  ---  //
vec3 XYZ_to_sRGB(vec3 x) {
    x = x * mat3x3( 3.2404542, -1.5371385, -0.4985314, -0.9692660, 1.8760108, 0.0415560, 0.0556434, -0.2040259, 1.0572252 );
    x = mix(1.055*pow(x, vec3(1./2.4)) - 0.055, 12.92*x, step(x,vec3(0.0031308)));
    return x;
}
 
vec3 sRGB_to_XYZ(vec3 x) {
    x = mix(pow((x + 0.055)/1.055,vec3(2.4)), x / 12.92, step(x,vec3(0.04045)));
    x = x * mat3x3( 0.4124564, 0.3575761, 0.1804375, 0.2126729, 0.7151522, 0.0721750, 0.0193339, 0.1191920, 0.9503041 );
    return x;
}
 
//  ---  Jzazbz  ---  //{
vec3 XYZ_to_Jzazbz(vec3 XYZ) {
    float b = 1.15;
    float g = 0.66;
    vec3 XYZprime = XYZ;
    XYZprime.x = XYZ.x * b - (b - 1) * XYZ.z;
    XYZprime.y = XYZ.y * g - (g - 1) * XYZ.x;
    XYZprime.z = XYZ.z;
    vec3 LMS = XYZprime * mat3x3(0.41478972, 0.579999, 0.0146480, -0.2015100, 1.120649, 0.0531008, -0.0166008, 0.264800, 0.6684799);
    float c1 = 3424 / pow(2.0,12.0);
    float c2 = 2413 / pow(2.0,7.0);
    float c3 = 2392 / pow(2.0,7.0);
    float n  = 2610 / pow(2.0,14.0);
    float p  = 1.7 * 2523 / pow(2.0,5.0);
    vec3 LMSprime = pow((c1 + c2 * pow(LMS/10000,vec3(n)))/(1 + c3 * pow(LMS/10000,vec3(n))),vec3(p));
    vec3 Izazbz = LMSprime * mat3x3(0.5, 0.5, 0.0, 3.524000, -4.066708, 0.542708, 0.199076, 1.096799, -1.295875);
    float d = -0.56;
    float d0 = 1.6295499532821566 * pow(10.0,-11.0);
    vec3 Jzazbz = Izazbz;
    Jzazbz.x = ((1 + d) * Izazbz.x)/(1 + d * Izazbz.x) - d0;
    return Jzazbz;
}    
 
vec3 Jzazbz_to_JzCzhz(vec3 Jzazbz) {
    float Cz = sqrt(Jzazbz.y*Jzazbz.y + Jzazbz.z*Jzazbz.z);
    float hz = atan(Jzazbz.z,Jzazbz.y);
    vec3 JzCzhz = vec3(Jzazbz.x,Cz,hz);
    return JzCzhz;
}
 
vec3 JzCzhz_Normalize(vec3 JzCzhz) {
    JzCzhz.x = JzCzhz.x*56.91964;
    JzCzhz.y = JzCzhz.y*40.05235;
    JzCzhz.z = (JzCzhz.z+2.761)/5.522;
    //-2.6274509803921568627450980392157
    //2.760784313725490196078431372549
    //Assume 2.761 both ways so +2.761 then / 5.522
    return JzCzhz;
}
 
vec3 JzCzhz_Denormalize(vec3 JzCzhz) {
    JzCzhz.x = JzCzhz.x/56.91964;
    JzCzhz.y = JzCzhz.y/40.05235;
    JzCzhz.z = JzCzhz.z * 5.522 - 2.761;
    return JzCzhz;
}
 
vec3 JzCzhz_to_Jzazbz(vec3 JzCzhz) {
    vec3 Jzazbz = vec3(JzCzhz.x,JzCzhz.y*cos(JzCzhz.z),JzCzhz.y*sin(JzCzhz.z));;
    return Jzazbz;
}
 
vec3 Jzazbz_to_XYZ(vec3 Jzazbz) {
    float d0 = 1.6295499532821566 * pow(10.0,-11.0);
    float d = -0.56;
    float Iz = (Jzazbz.x + d0) / (1 + d - d * (Jzazbz.x + d0));
    vec3 Izazbz = vec3(Iz,Jzazbz.y,Jzazbz.z);
    vec3 LMSprime = Izazbz * mat3x3(1.0, 0.138605043271539, 0.0580473161561189, 1.0, -0.138605043271539, -0.0580473161561189, 1.0, -0.0960192420263189, -0.811891896056039);
    float c1 = 3424 / pow(2.0,12.0);
    float c2 = 2413 / pow(2.0,7.0);
    float c3 = 2392 / pow(2.0,7.0);
    float n  = 2610 / pow(2.0,14.0);
    float p  = 1.7 * 2523 / pow(2.0,5.0);
    vec3 LMS = 10000 * pow((c1 - pow(LMSprime,vec3(1.0/p)))/(c3 * pow(LMSprime,vec3(1.0/p)) - c2),vec3(1.0/n));
    vec3 XYZprime = LMS * mat3x3(1.92422643578761, -1.00479231259537, 0.037651404030618, 0.350316762094999, 0.726481193931655, -0.065384422948085, -0.0909828109828476, -0.312728290523074, 1.52276656130526);
    float b = 1.15;
    float g = 0.66;
    vec3 XYZ = XYZprime;
    XYZ.x = (XYZprime.x + (b - 1.0) * XYZprime.z) / b;
    XYZ.y = (XYZprime.y + (g - 1.0) * XYZ.x) / g;
    XYZ.z = XYZprime.z;
    return XYZ;
}