obs-StreamFX/data/effects/color-grade.effect

// Parameters
uniform float4x4 ViewProj;
uniform texture2d image;
uniform float4 pLift;
uniform float4 pGamma;
uniform float4 pGain;
uniform float4 pOffset;
uniform int pTintDetection; // 0 = HSV, 1 = HSL, 2 = YUV HD SDR
uniform int pTintMode; // 0 = Linear, 1 = Exp, 2 = Exp2, 3 = Log, 4 = Log10
uniform float pTintExponent;
uniform float3 pTintLow;
uniform float3 pTintMid;
uniform float3 pTintHig;
uniform float4 pCorrection;

#define TINT_DETECTION_HSV				0
#define TINT_DETECTION_HSL				1
#define TINT_DETECTION_YUV_SDR			2

#define TINT_MODE_LINEAR				0
#define TINT_MODE_EXP					1
#define TINT_MODE_EXP2					2
#define TINT_MODE_LOG					3
#define TINT_MODE_LOG10					4

#define C_e 2,7182818284590452353602874713527
#define C_log2_e 1.4426950408889634073599246810019 // Windows calculator: log(e(1)) / log(2)

// Data
sampler_state def_sampler {
	Filter    = Point;
	AddressU  = Clamp;
	AddressV  = Clamp;
	MinLOD    = 0;
	MaxLOD    = 0;
};

struct VertDataIn {
	float4 pos : POSITION;
	float2 uv  : TEXCOORD0;
};

struct VertDataOut {
	float4 pos : POSITION;
	float2 uv  : TEXCOORD0;
};

VertDataOut VSDefault(VertDataIn v)
{
	VertDataOut ov;
	ov.pos = mul(float4(v.pos.xyz, 1.0), ViewProj);
	ov.uv = v.uv;
	return ov;
}

// Utility functions -----------------------------------------------------------
float4 RGBtoYUV(float4 rgba, float3x3 yuv) {
	return float4(
		rgba.r * yuv._m00 + rgba.g * yuv._m01 + rgba.b * yuv._m02,
		rgba.r * yuv._m10 + rgba.g * yuv._m11 + rgba.b * yuv._m12,
		rgba.r * yuv._m20 + rgba.g * yuv._m21 + rgba.b * yuv._m22,
		rgba.a
	) + float4(0,0.5,0.5,0);
}

float4 YUVtoRGB(float4 yuva, float3x3 yuvi) {
	yuva.gb -= 0.5;
	return float4(
		yuva.r * yuvi._m00 + yuva.g * yuvi._m01 + yuva.b * yuvi._m02,
		yuva.r * yuvi._m10 + yuva.g * yuvi._m11 + yuva.b * yuvi._m12,
		yuva.r * yuvi._m20 + yuva.g * yuvi._m21 + yuva.b * yuvi._m22,
		yuva.a);
}

float4 RGBtoHSV(float4 RGBA) {
	const float4 K = float4(0.0, -1.0 / 3.0, 2.0 / 3.0, -1.0);
	const float e = 1.0e-10;
	float4 p = lerp(float4(RGBA.bg, K.wz), float4(RGBA.gb, K.xy), step(RGBA.b, RGBA.g));
	float4 q = lerp(float4(p.xyw, RGBA.r), float4(RGBA.r, p.yzx), step(p.x, RGBA.r));
	float d = q.x - min(q.w, q.y);
	return float4(abs(q.z + (q.w - q.y) / (6.0 * d + e)), d / (q.x + e), q.x, RGBA.a);
}

float4 HSVtoRGB(float4 HSVA) {
	const float4 K = float4(1.0, 2.0 / 3.0, 1.0 / 3.0, 3.0);
	float4 v = float4(0,0,0,0);
	v.rgb = HSVA.z * lerp(K.xxx, clamp(abs(frac(HSVA.xxx + K.xyz) * 6.0 - K.www) - K.xxx, 0.0, 1.0), HSVA.y);
	v.a = HSVA.a;
	return v;
}

float4 HSLtoRGB(float4 HSLA) {
    float3 rgb = clamp(
		abs(
			fmod(
				HSLA.x * 6.0 + float3(0.0, 4.0, 2.0),
				6.0
			) - 3.0
		) - 1.0,
		0.0,
		1.0
	);
    return float4(HSLA.z + HSLA.y * (rgb - 0.5) * (1.0 - abs(2.0 * HSLA.z - 1.0)), HSLA.a);
}

float4 RGBtoHSL(float4 RGBA) {
	float h = 0.0;
	float s = 0.0;
	float l = 0.0;
	float r = RGBA.r;
	float g = RGBA.g;
	float b = RGBA.b;
	float cMin = min( r, min( g, b ) );
	float cMax = max( r, max( g, b ) );

	l = ( cMax + cMin ) / 2.0;
	if ( cMax > cMin ) {
		float cDelta = cMax - cMin;
        
		//s = l < .05 ? cDelta / ( cMax + cMin ) : cDelta / ( 2.0 - ( cMax + cMin ) ); Original
		s = l < .0 ? cDelta / ( cMax + cMin ) : cDelta / ( 2.0 - ( cMax + cMin ) );
        
		if ( r == cMax ) {
			h = ( g - b ) / cDelta;
		} else if ( g == cMax ) {
			h = 2.0 + ( b - r ) / cDelta;
		} else {
			h = 4.0 + ( r - g ) / cDelta;
		}

		if ( h < 0.0) {
			h += 6.0;
		}
		h = h / 6.0;
	}
	return float4( h, s, l, RGBA.a );
}

// Actual Code -----------------------------------------------------------------
float4 Lift(float4 v)
{
	v.rgb = pLift.aaa + v.rgb;
	v.rgb = pLift.rgb + v.rgb;
	return v;
}

float4 Gamma(float4 v)
{
	v.rgb = pow(pow(v.rgb, pGamma.rgb), pGamma.aaa);
	return v;
}

float4 Gain(float4 v)
{
	v.rgb *= pGain.rgb;
	v.rgb *= pGain.a;
	return v;
}

float4 Offset(float4 v)
{
	v.rgb = pOffset.aaa + v.rgb;
	v.rgb = pOffset.rgb + v.rgb;
	return v;
}

float4 Tint(float4 v)
{
	float value = 0.;
	if (pTintDetection == TINT_DETECTION_HSV) { // HSV
		value = RGBtoHSV(v).z;
	} else if (pTintDetection == TINT_DETECTION_HSL) { // HSL
		value = RGBtoHSL(v).z;
	} else if (pTintDetection == TINT_DETECTION_YUV_SDR) { // YUV HD SDR
		const float3x3 mYUV709n = { // Normalized
			0.2126, 0.7152, 0.0722,
			-0.1145721060573399, -0.3854278939426601, 0.5,
			0.5, -0.4541529083058166, -0.0458470916941834
		};
		value = RGBtoYUV(v, mYUV709n).r;
	}

	if (pTintMode == TINT_MODE_LINEAR) { // Linear
	} else if (pTintMode == TINT_MODE_EXP) { // Exp
		value = 1.0 - exp2(value * pTintExponent * -C_log2_e);		
	} else if (pTintMode == TINT_MODE_EXP2) { // Exp2
		value = 1.0 - exp2(value * value * pTintExponent * pTintExponent * -C_log2_e);
	} else if (pTintMode == TINT_MODE_LOG) { // Log
		value = (log2(value) + 2.) / 2.333333;
	} else if (pTintMode == TINT_MODE_LOG10) { // Log10
		value = (log10(value) + 1.) / 2.;		
	}

	float3 tint = float3(0,0,0);
	if (value > 0.5) {
		tint = lerp(pTintMid, pTintHig, value * 2.0 - 1.0);
	} else {
		tint = lerp(pTintLow, pTintMid, value * 2.0);
	}
	v.rgb *= tint;
	return v;
}

float4 Correction(float4 v)
{
	float4 v1 = RGBtoHSV(v);
	v1.r += pCorrection.r;
	v1.g *= pCorrection.g;
	v1.b *= pCorrection.b;
	float4 v2 = HSVtoRGB(v1);
	v2.rgb = ((v2.rgb - 0.5) * max(pCorrection.a, 0)) + 0.5;
	return v2;
}

float4 PSColorGrade(VertDataOut v) : TARGET
{
	return Correction(Tint(Offset(Gain(Gamma(Lift(image.Sample(def_sampler, v.uv)))))));
}

technique Draw
{
	pass
	{
		vertex_shader = VSDefault(v);
		pixel_shader = PSColorGrade(v);		
	}
}