cColor: Fixed OKLab, added LogC4 conversion

Author: papadanku

shaders/cRaySchism.fx

@@ -19,29 +19,29 @@
 
 // Bloom-specific settings
 #if ENABLE_BLOOM
-    uniform int _RenderMode <
+    uniform int _BloomRenderMode <
         ui_label = "Bloom";
         ui_type = "combo";
         ui_items = "Base + Bloom\0Bloom\0";
     > = 0;
 
-    uniform float _Threshold <
+    uniform float _BloomThreshold <
         ui_category = "Bloom";
         ui_label = "Threshold";
         ui_type = "slider";
         ui_min = 0.0;
         ui_max = 1.0;
     > = 0.8;
 
-    uniform float _Smooth <
+    uniform float _BloomSmoothing <
         ui_category = "Bloom";
         ui_label = "Smoothing";
         ui_type = "slider";
         ui_min = 0.0;
         ui_max = 1.0;
     > = 0.5;
 
-    uniform float _Intensity <
+    uniform float _BloomIntensity <
         ui_category = "Bloom";
         ui_label = "Intensity";
         ui_type = "slider";
@@ -50,7 +50,7 @@
         ui_max = 1.0;
     > = 0.5;
 
-    uniform float3 _ColorShift <
+    uniform float3 _BloomColorShift <
         ui_category = "Bloom";
         ui_label = "Color Shift (RGB)";
         ui_type = "color";
@@ -63,37 +63,37 @@
 #if ENABLE_AUTOEXPOSURE
     uniform float _Frametime < source = "frametime"; >;
 
-    uniform int _Meter <
-        ui_category = "Auto-Exposure";
+    uniform int _ExposureMeter <
+        ui_category = "Exposure";
         ui_label = "Method";
         ui_type = "combo";
         ui_items = "Average\0Spot\0";
     > = 0;
 
-    uniform float _Scale <
-        ui_category = "Auto-Exposure";
+    uniform float _ExposureScale <
+        ui_category = "Exposure";
         ui_label = "Spot Scale";
         ui_type = "slider";
         ui_min = 0.0;
         ui_max = 1.0;
     > = 0.5;
 
-    uniform float2 _Offset <
-        ui_category = "Auto-Exposure";
+    uniform float2 _ExposureOffset <
+        ui_category = "Exposure";
         ui_label = "Spot Offset";
         ui_type = "slider";
         ui_min = -1.0;
         ui_max = 1.0;
     > = 0.0;
 
-    uniform bool _DisplayAverageLumaOverlay <
-        ui_category = "Auto-Exposure";
+    uniform bool _ExposureLumaOverlay <
+        ui_category = "Exposure";
         ui_label = "Display Average Luminance";
         ui_type = "radio";
     > = false;
 
-    uniform bool _DisplaySpotMeterOverlay <
-        ui_category = "Auto-Exposure";
+    uniform bool _ExposureSpotMeterOverlay <
+        ui_category = "Exposure";
         ui_label = "Display Spot Metering";
         ui_type = "radio";
     > = false;
@@ -163,8 +163,8 @@
         #else
             SpotMeterTex.y /= ASPECT_RATIO;
         #endif
-        SpotMeterTex *= _Scale;
-        SpotMeterTex += float2(_Offset.x, -_Offset.y);
+        SpotMeterTex *= _ExposureScale;
+        SpotMeterTex += float2(_ExposureOffset.x, -_ExposureOffset.y);
         SpotMeterTex = (SpotMeterTex * 0.5) + 0.5;
 
         return SpotMeterTex;
@@ -178,8 +178,8 @@
                 Height conversion | [0, 1] -> [-N, N]
         */
         float2 OverlayPos = UnormTex;
-        OverlayPos -= float2(_Offset.x, -_Offset.y);
-        OverlayPos /= _Scale;
+        OverlayPos -= float2(_ExposureOffset.x, -_ExposureOffset.y);
+        OverlayPos /= _ExposureScale;
 
         // Shrink the UV so [-1, 1] fills a square
         #if BUFFER_WIDTH > BUFFER_HEIGHT
@@ -189,7 +189,7 @@
         #endif
 
         // Create the needed mask; output 1 if the texcoord is within square range
-        float Factor = 1.0 * _Scale;
+        float Factor = 1.0 * _ExposureScale;
         float SquareMask = all(abs(OverlayPos) <= Factor);
         float DotMask = CProcedural_GetAntiAliasShape(length(OverlayPos), Factor * 0.1);
 
@@ -250,7 +250,7 @@
         // Apply auto-exposure to the backbuffer
         #if ENABLE_AUTOEXPOSURE
             // Store log luminance in the alpha channel
-            if (_Meter == 1)
+            if (_ExposureMeter == 1)
             {
                 float3 ColorArea = CShade_BackBuffer2D(GetSpotMeterTex(Input.Tex0)).rgb;
                 Luminance = CCamera_GetLogLuminance(ColorArea.rgb);
@@ -267,18 +267,18 @@
         #endif
 
         // Thresholding phase
-        const float Knee = mad(_Threshold, _Smooth, 1e-5);
-        const float3 Curve = float3(_Threshold - Knee, Knee * 2.0, 0.25 / Knee);
+        const float Knee = mad(_BloomThreshold, _BloomSmoothing, 1e-5);
+        const float3 Curve = float3(_BloomThreshold - Knee, Knee * 2.0, 0.25 / Knee);
 
         // Under-threshold
         float Brightness = CColor_GetLuma(Color.rgb, 3);
         float ResponseCurve = clamp(Brightness - Curve.x, 0.0, Curve.y);
         ResponseCurve = Curve.z * ResponseCurve * ResponseCurve;
 
         // Combine and apply the brightness response curve
-        Color = Color * max(ResponseCurve, Brightness - _Threshold) / max(Brightness, 1e-10);
+        Color = Color * max(ResponseCurve, Brightness - _BloomThreshold) / max(Brightness, 1e-10);
 
-        return float4(Color.rgb * _ColorShift, Luminance);
+        return float4(Color.rgb * _BloomColorShift, Luminance);
     }
 
     #define CREATE_PS_DOWNSCALE(METHOD_NAME, SAMPLER, FLICKER_FILTER) \
@@ -325,8 +325,8 @@ float4 PS_Composite(CShade_VS2PS_Quad Input) : SV_TARGET0
 
     // Bloom composition
     #if ENABLE_BLOOM
-        float3 BloomColor = tex2D(SampleTempTex1, Input.Tex0).rgb * _Intensity;
-        BaseColor = (_RenderMode == 0) ? BaseColor + BloomColor : BloomColor;
+        float3 BloomColor = tex2D(SampleTempTex1, Input.Tex0).rgb * _BloomIntensity;
+        BaseColor = (_BloomRenderMode == 0) ? BaseColor + BloomColor : BloomColor;
     #endif
 
     // Apply tonemapping
@@ -336,17 +336,17 @@ float4 PS_Composite(CShade_VS2PS_Quad Input) : SV_TARGET0
     #if ENABLE_AUTOEXPOSURE
         float2 UnormTex = (Input.Tex0 * 2.0) - 1.0;
 
-        if (_DisplaySpotMeterOverlay)
+        if (_ExposureSpotMeterOverlay)
         {
             ApplySpotMeterOverlay(BaseColor, UnormTex, NonExposedColor);
         }
 
-        if (_DisplayAverageLumaOverlay)
+        if (_ExposureLumaOverlay)
         {
             ApplyAverageLumaOverlay(BaseColor, UnormTex, ExposureData);
         }
     #endif
-
+    BaseColor = saturate(BaseColor);
     return CBlend_OutputChannels(float4(BaseColor, _CShadeAlphaFactor));
 }
 
@@ -363,7 +363,6 @@ float4 PS_Composite(CShade_VS2PS_Quad Input) : SV_TARGET0
         RenderTarget0 = RENDER_TARGET; \
     }
 
-
 technique CShade_RaySchism < ui_tooltip = "CShade's Color Multi-tool."; >
 {
     #if ENABLE_BLOOM

shaders/shared/cColor.fxh

@@ -122,6 +122,28 @@
         return Output;
     }
 
+    float3 CColor_GetRGBfromHSV(float3 HSV)
+    {
+        float H = HSV.x * 6.0;
+        float S = HSV.y;
+        float V = HSV.z;
+
+        float I = floor(H);
+        float J = V * (1.0 - S);
+        float K = V * (1.0 - S * (H - I));
+        float L = V * (1.0 - S * (1.0 - (H - I)));
+        float4 P = float4(V, J, K, L);
+
+        float3 O = 0.0;
+        O = (I < 6) ? P.xyz : O;
+        O = (I < 5) ? P.wyx : O;
+        O = (I < 4) ? P.yzx : O;
+        O = (I < 3) ? P.yxw : O;
+        O = (I < 2) ? P.zxy : O;
+        O = (I < 1) ? P.xwy : O;
+        return O;
+    }
+
     float3 CColor_GetHSLfromRGB(float3 Color)
     {
         float MinRGB = min(min(Color.r, Color.g), Color.b);
@@ -232,12 +254,11 @@
         LMS.g = dot(Color, float3(0.2119034982, 0.6806995451, 0.1073969566));
         LMS.b = dot(Color, float3(0.0883024619, 0.2817188376, 0.6299787005));
         LMS = pow(LMS, 1.0 / 3.0);
-        LMS = dot(Color, float3(0.2104542553, 0.7936177850, -0.0040720468));
-        LMS = dot(Color, float3(1.9779984951, -2.4285922050, 0.4505937099));
-        LMS = dot(Color, float3(0.0259040371, 0.7827717662, -0.8086757660));
+        LMS.r = dot(LMS, float3(0.2104542553, 0.7936177850, -0.0040720468));
+        LMS.g = dot(LMS, float3(1.9779984951, -2.4285922050, 0.4505937099));
+        LMS.b = dot(LMS, float3(0.0259040371, 0.7827717662, -0.8086757660));
         return LMS;
     }
-
     float3 CColor_GetOKLchFromOKLab(float3 Color)
     {
         float Pi2 = CMath_GetPi() * 2.0;
@@ -252,4 +273,49 @@
     {
         return CColor_GetOKLchFromOKLab(CColor_GetOKLabFromRGB(Color));
     }
+
+    /*
+        LogC conversion
+        https://www.arri.com/en/learn-help/learn-help-camera-system/image-science/log-c
+    */
+
+    struct CCamera_LogC_Constants
+    {
+        float A, B, C, S, T;
+    };
+
+    CCamera_LogC_Constants CCamera_GetLogC_Constants()
+    {
+        CCamera_LogC_Constants Output;
+        const float A = (exp2(18.0) - 16.0) / 117.45;
+        const float B = (1023.0 - 95.0) / 1023.0;
+        const float C = 95.0 / 1023.0;
+        const float S = (7.0 * log(2.0) * exp2(7.0 - 14.0 * C / B)) / (A * B);
+        const float T = (exp2(14.0 * (-C / B) + 6.0) - 64.0) / A;
+        Output.A = A;
+        Output.B = B;
+        Output.C = C;
+        Output.S = S;
+        Output.T = T;
+    }
+
+    // LogC4 Curve Encoding Function
+    float3 CCamera_EncodeLogC(float3 Color)
+    {
+        CCamera_LogC_Constants LogC = CCamera_GetLogC_Constants();
+        float3 A = (Color - LogC.T) / LogC.S;
+        float3 B = (log2(LogC.A * Color + 64.0) - 6.0) / 14.0 * LogC.B + LogC.C;
+        return lerp(B, A, Color < LogC.T);
+    }
+
+    // LogC4 Curve Decoding Function
+    float3 CCamera_DecodeLogC(float3 Color)
+    {
+        CCamera_LogC_Constants LogC = CCamera_GetLogC_Constants();
+        float3 A = Color * LogC.S + LogC.T;
+        float3 P = 14.0 * (Color - LogC.C) / LogC.B + 6.0;
+        float3 B = (exp2(P) - 64.0) / LogC.A;
+
+        return lerp(B, A, Color < 0.0);
+    }
 #endif