Add automatic linear space detection

- Added a function to estimate gamma space of RGB profiles (only a subset). This function is still undocumented.
- Lcms now automatically turns off optimizations when 16-bit on RGB and input linear space is found.

12 files changed, 207 insertions, 68 deletions

diff --git a/include/lcms2.h b/include/lcms2.h
index c748e51..61e2ab3 100644
--- a/include/lcms2.h
+++ b/include/lcms2.h
@@ -1907,6 +1907,8 @@ CMSAPI cmsBool          CMSEXPORT cmsDetectDestinationBlackPoint(cmsCIEXYZ* Blac
 // Estimate total area coverage
 CMSAPI cmsFloat64Number CMSEXPORT cmsDetectTAC(cmsHPROFILE hProfile);
 
+// Estimate gamma space, alwasys positive. Returns -1 on error.
+CMSAPI cmsFloat64Number CMSEXPORT cmsDetectRGBProfileGamma(cmsHPROFILE hProfile, cmsFloat64Number thereshold);
 
 // Poor man's gamut mapping
 CMSAPI cmsBool          CMSEXPORT cmsDesaturateLab(cmsCIELab* Lab,
diff --git a/plugins/fast_float/src/fast_16_tethra.c b/plugins/fast_float/src/fast_16_tethra.c
index aad207f..d76c65a 100644
--- a/plugins/fast_float/src/fast_16_tethra.c
+++ b/plugins/fast_float/src/fast_16_tethra.c
@@ -317,7 +317,6 @@ cmsBool Optimize16BitRGBTransform(_cmsTransform2Fn* TransformFn,
                                   cmsUInt32Number* OutputFormat, 
                                   cmsUInt32Number* dwFlags)      
 {
-    cmsStage* mpe;
     Performance16Data* p16;
     cmsContext ContextID;
     _cmsStageCLutData* data;
@@ -353,14 +352,7 @@ cmsBool Optimize16BitRGBTransform(_cmsTransform2Fn* TransformFn,
         cmsSigCurveSetElemType, cmsSigCurveSetElemType,
         NULL, NULL)) return FALSE;
 
-
-   // Named color pipelines cannot be optimized either
-   for (mpe = cmsPipelineGetPtrToFirstStage(*Lut);
-         mpe != NULL;
-         mpe = cmsStageNext(mpe)) {
-            if (cmsStageType(mpe) == cmsSigNamedColorElemType) return FALSE;
-    }
-
+   
     ContextID = cmsGetPipelineContextID(*Lut);
     newFlags = *dwFlags | cmsFLAGS_FORCE_CLUT;
 
diff --git a/plugins/fast_float/src/fast_8_tethra.c b/plugins/fast_float/src/fast_8_tethra.c
index 26a5a5d..9a724a6 100644
--- a/plugins/fast_float/src/fast_8_tethra.c
+++ b/plugins/fast_float/src/fast_8_tethra.c
@@ -346,7 +346,6 @@ cmsBool Optimize8BitRGBTransform(_cmsTransform2Fn* TransformFn,
     cmsPipeline* OptimizedLUT = NULL, *LutPlusCurves = NULL;    
     cmsStage* OptimizedCLUTmpe;
     cmsStage* OptimizedPrelinMpe;
-    cmsStage* mpe;
     Performance8Data* p8;
     cmsUInt16Number* MyTable[3];
     cmsContext ContextID;
@@ -365,14 +364,7 @@ cmsBool Optimize8BitRGBTransform(_cmsTransform2Fn* TransformFn,
     if (T_COLORSPACE(*InputFormat)  != PT_RGB) return FALSE;
    
     OriginalLut = *Lut;
-
-   // Named color pipelines cannot be optimized either
-   for (mpe = cmsPipelineGetPtrToFirstStage(OriginalLut);
-         mpe != NULL;
-         mpe = cmsStageNext(mpe)) {
-            if (cmsStageType(mpe) == cmsSigNamedColorElemType) return FALSE;
-    }
-
+   
     ContextID = cmsGetPipelineContextID(OriginalLut);
     nGridPoints      = _cmsReasonableGridpointsByColorspace(cmsSigRgbData, *dwFlags);
 
diff --git a/plugins/fast_float/src/fast_float_cmyk.c b/plugins/fast_float/src/fast_float_cmyk.c
index d4a8261..a0a23de 100644
--- a/plugins/fast_float/src/fast_float_cmyk.c
+++ b/plugins/fast_float/src/fast_float_cmyk.c
@@ -331,7 +331,6 @@ cmsBool OptimizeCLUTCMYKTransform(_cmsTransform2Fn* TransformFn,
     int nGridPoints;    
     cmsPipeline* OptimizedLUT = NULL;    
     cmsStage* OptimizedCLUTmpe;
-    cmsStage* mpe;
     FloatCMYKData* pcmyk;
     cmsContext ContextID;
     _cmsStageCLutData* data;
@@ -349,14 +348,7 @@ cmsBool OptimizeCLUTCMYKTransform(_cmsTransform2Fn* TransformFn,
     if (T_COLORSPACE(*InputFormat)  != PT_CMYK) return FALSE;
    
     OriginalLut = *Lut;
-
-   // Named color pipelines cannot be optimized either
-   for (mpe = cmsPipelineGetPtrToFirstStage(OriginalLut);
-         mpe != NULL;
-         mpe = cmsStageNext(mpe)) {
-            if (cmsStageType(mpe) == cmsSigNamedColorElemType) return FALSE;
-    }
-
+   
     ContextID = cmsGetPipelineContextID(OriginalLut);
     nGridPoints = _cmsReasonableGridpointsByColorspace(cmsSigRgbData, *dwFlags);
              
diff --git a/plugins/fast_float/src/fast_float_lab.c b/plugins/fast_float/src/fast_float_lab.c
index d392a84..2f31d7d 100644
--- a/plugins/fast_float/src/fast_float_lab.c
+++ b/plugins/fast_float/src/fast_float_lab.c
@@ -369,7 +369,6 @@ cmsBool OptimizeCLUTLabTransform(_cmsTransform2Fn* TransformFn,
     int nGridPoints;    
     cmsPipeline* OptimizedLUT = NULL;    
     cmsStage* OptimizedCLUTmpe;
-    cmsStage* mpe;
     LabCLUTdata* pfloat;
     cmsContext ContextID;
     _cmsStageCLutData* data;
@@ -389,14 +388,7 @@ cmsBool OptimizeCLUTLabTransform(_cmsTransform2Fn* TransformFn,
     if (T_COLORSPACE(*InputFormat) != PT_Lab) return FALSE;
 
     OriginalLut = *Lut;
-
-    // Named color pipelines cannot be optimized either
-    for (mpe = cmsPipelineGetPtrToFirstStage(OriginalLut);
-        mpe != NULL;
-        mpe = cmsStageNext(mpe)) {
-        if (cmsStageType(mpe) == cmsSigNamedColorElemType) return FALSE;
-    }
-
+    
     ContextID = cmsGetPipelineContextID(OriginalLut);
     nGridPoints = GetGridpoints(*dwFlags);
              
diff --git a/plugins/fast_float/src/fast_float_tethra.c b/plugins/fast_float/src/fast_float_tethra.c
index 0e3015a..29ebde5 100644
--- a/plugins/fast_float/src/fast_float_tethra.c
+++ b/plugins/fast_float/src/fast_float_tethra.c
@@ -239,7 +239,6 @@ cmsBool OptimizeCLUTRGBTransform(_cmsTransform2Fn* TransformFn,
     int nGridPoints;    
     cmsPipeline* OptimizedLUT = NULL;    
     cmsStage* OptimizedCLUTmpe;
-    cmsStage* mpe;
     FloatCLUTData* pfloat;
     cmsContext ContextID;
     _cmsStageCLutData* data;
@@ -258,14 +257,7 @@ cmsBool OptimizeCLUTRGBTransform(_cmsTransform2Fn* TransformFn,
     if (T_COLORSPACE(*InputFormat) != PT_RGB) return FALSE;
 
     OriginalLut = *Lut;
-
-   // Named color pipelines cannot be optimized either
-   for (mpe = cmsPipelineGetPtrToFirstStage(OriginalLut);
-         mpe != NULL;
-         mpe = cmsStageNext(mpe)) {
-            if (cmsStageType(mpe) == cmsSigNamedColorElemType) return FALSE;
-    }
-
+   
     ContextID        = cmsGetPipelineContextID(OriginalLut);
     nGridPoints      = _cmsReasonableGridpointsByColorspace(cmsSigRgbData, *dwFlags);
              
diff --git a/src/cmsgmt.c b/src/cmsgmt.c
index 75904e4..f28e251 100644
--- a/src/cmsgmt.c
+++ b/src/cmsgmt.c
@@ -1,7 +1,7 @@
 //---------------------------------------------------------------------------------

 //

 //  Little Color Management System

-//  Copyright (c) 1998-2020 Marti Maria Saguer

+//  Copyright (c) 1998-2021 Marti Maria Saguer

 //

 // Permission is hereby granted, free of charge, to any person obtaining

 // a copy of this software and associated documentation files (the "Software"),

@@ -588,3 +588,67 @@ cmsBool CMSEXPORT cmsDesaturateLab(cmsCIELab* Lab,
 

     return TRUE;

 }

+

+// Detect whatever a given ICC profile works in linear (gamma 1.0) space

+// Actually, doing that "well" is quite hard, since every component may behave completely different.

+// Since the true point of this function is to detect suitable optimizations, I am imposing some requirements 

+// that simplifies things: only RGB, and only profiles that can got in both directions.

+// The algorith obtains Y from a syntetical gray R=G=B. Then least squares fitting is used to estimate gamma. 

+// For gamma close to 1.0, RGB is linear. On profiles not supported, -1 is returned.

+

+cmsFloat64Number CMSEXPORT cmsDetectRGBProfileGamma(cmsHPROFILE hProfile, cmsFloat64Number thereshold)

+{

+    cmsContext ContextID;

+    cmsHPROFILE hXYZ;

+    cmsHTRANSFORM xform;

+    cmsToneCurve* Y_curve;

+    cmsUInt16Number rgb[256][3];

+    cmsCIEXYZ XYZ[256];

+    cmsFloat32Number Y_normalized[256];

+    cmsFloat64Number gamma;

+    cmsProfileClassSignature cl;

+    int i;

+

+    if (cmsGetColorSpace(hProfile) != cmsSigRgbData)

+        return -1;

+

+    cl = cmsGetDeviceClass(hProfile);

+    if (cl != cmsSigInputClass && cl != cmsSigDisplayClass && 

+        cl != cmsSigOutputClass && cl != cmsSigColorSpaceClass)

+        return -1;

+

+    ContextID = cmsGetProfileContextID(hProfile);

+    hXYZ = cmsCreateXYZProfileTHR(ContextID);

+    xform = cmsCreateTransformTHR(ContextID, hProfile, TYPE_RGB_16, hXYZ, TYPE_XYZ_DBL, 

+                                    INTENT_RELATIVE_COLORIMETRIC, cmsFLAGS_NOOPTIMIZE);

+

+    if (xform == NULL) { // If not RGB or forward direction is not supported, regret with the previous error

+

+        cmsCloseProfile(hXYZ);        

+        return -1;

+    }

+

+    for (i = 0; i < 256; i++) {

+        rgb[i][0] = rgb[i][1] = rgb[i][2] = FROM_8_TO_16(i);       

+    }

+

+    cmsDoTransform(xform, rgb, XYZ, 256);

+

+    cmsDeleteTransform(xform);

+    cmsCloseProfile(hXYZ);

+

+    for (i = 0; i < 256; i++) {

+        Y_normalized[i] = (cmsFloat32Number) XYZ[i].Y;

+    }

+

+    Y_curve = cmsBuildTabulatedToneCurveFloat(ContextID, 256, Y_normalized);

+    if (Y_curve == NULL)     

+        return -1;

+    

+    gamma = cmsEstimateGamma(Y_curve, thereshold);

+

+    cmsFreeToneCurve(Y_curve);

+

+    return gamma;

+}

+

diff --git a/src/cmsopt.c b/src/cmsopt.c
index c760551..56cdf29 100644
--- a/src/cmsopt.c
+++ b/src/cmsopt.c
@@ -647,7 +647,6 @@ cmsBool OptimizeByResampling(cmsPipeline** Lut, cmsUInt32Number Intent, cmsUInt3
 {
     cmsPipeline* Src = NULL;
     cmsPipeline* Dest = NULL;
-    cmsStage* mpe;
     cmsStage* CLUT;
     cmsStage *KeepPreLin = NULL, *KeepPostLin = NULL;
     cmsUInt32Number nGridPoints;
@@ -669,7 +668,7 @@ cmsBool OptimizeByResampling(cmsPipeline** Lut, cmsUInt32Number Intent, cmsUInt3
     if (ColorSpace == (cmsColorSpaceSignature)0 ||
         OutputColorSpace == (cmsColorSpaceSignature)0) return FALSE;
 
-    nGridPoints      = _cmsReasonableGridpointsByColorspace(ColorSpace, *dwFlags);
+    nGridPoints = _cmsReasonableGridpointsByColorspace(ColorSpace, *dwFlags);
 
     // For empty LUTs, 2 points are enough
     if (cmsPipelineStageCount(*Lut) == 0)
@@ -677,13 +676,6 @@ cmsBool OptimizeByResampling(cmsPipeline** Lut, cmsUInt32Number Intent, cmsUInt3
 
     Src = *Lut;
 
-    // Named color pipelines cannot be optimized either
-    for (mpe = cmsPipelineGetPtrToFirstStage(Src);
-        mpe != NULL;
-        mpe = cmsStageNext(mpe)) {
-            if (cmsStageType(mpe) == cmsSigNamedColorElemType) return FALSE;
-    }
-
     // Allocate an empty LUT
     Dest =  cmsPipelineAlloc(Src ->ContextID, Src ->InputChannels, Src ->OutputChannels);
     if (!Dest) return FALSE;
@@ -1051,7 +1043,6 @@ cmsBool OptimizeByComputingLinearization(cmsPipeline** Lut, cmsUInt32Number Inte
     cmsStage* OptimizedCLUTmpe;
     cmsColorSpaceSignature ColorSpace, OutputColorSpace;
     cmsStage* OptimizedPrelinMpe;
-    cmsStage* mpe;
     cmsToneCurve** OptimizedPrelinCurves;
     _cmsStageCLutData* OptimizedPrelinCLUT;
 
@@ -1072,14 +1063,7 @@ cmsBool OptimizeByComputingLinearization(cmsPipeline** Lut, cmsUInt32Number Inte
     }
 
     OriginalLut = *Lut;
-
-   // Named color pipelines cannot be optimized either
-   for (mpe = cmsPipelineGetPtrToFirstStage(OriginalLut);
-         mpe != NULL;
-         mpe = cmsStageNext(mpe)) {
-            if (cmsStageType(mpe) == cmsSigNamedColorElemType) return FALSE;
-    }
-
+   
     ColorSpace       = _cmsICCcolorSpace((int) T_COLORSPACE(*InputFormat));
     OutputColorSpace = _cmsICCcolorSpace((int) T_COLORSPACE(*OutputFormat));
 
@@ -1918,6 +1902,7 @@ cmsBool CMSEXPORT _cmsOptimizePipeline(cmsContext ContextID,
     _cmsOptimizationPluginChunkType* ctx = ( _cmsOptimizationPluginChunkType*) _cmsContextGetClientChunk(ContextID, OptimizationPlugin);
     _cmsOptimizationCollection* Opts;
     cmsBool AnySuccess = FALSE;
+    cmsStage* mpe;
 
     // A CLUT is being asked, so force this specific optimization
     if (*dwFlags & cmsFLAGS_FORCE_CLUT) {
@@ -1932,6 +1917,13 @@ cmsBool CMSEXPORT _cmsOptimizePipeline(cmsContext ContextID,
         return TRUE;
     }
 
+    // Named color pipelines cannot be optimized 
+    for (mpe = cmsPipelineGetPtrToFirstStage(*PtrLut);
+        mpe != NULL;
+        mpe = cmsStageNext(mpe)) {
+        if (cmsStageType(mpe) == cmsSigNamedColorElemType) return FALSE;
+    }
+
     // Try to get rid of identities and trivial conversions.
     AnySuccess = PreOptimize(*PtrLut);
 
diff --git a/src/cmsxform.c b/src/cmsxform.c
index 9d182e1..ac7792a 100644
--- a/src/cmsxform.c
+++ b/src/cmsxform.c
@@ -1081,6 +1081,15 @@ cmsHTRANSFORM CMSEXPORT cmsCreateExtendedTransform(cmsContext ContextID,
         return NULL;
     }
 
+    // Check whatever the transform is 16 bits and involves linear RGB in first profile. If so, disable optimizations
+    if (EntryColorSpace == cmsSigRgbData && T_BYTES(InputFormat) == 2 && !(dwFlags & cmsFLAGS_NOOPTIMIZE))
+    {
+        cmsFloat64Number gamma = cmsDetectRGBProfileGamma(hProfiles[0], 0.1);
+
+        if (gamma > 0 && gamma < 1.6)
+            dwFlags |= cmsFLAGS_NOOPTIMIZE;
+    }
+
     // Create a pipeline with all transformations
     Lut = _cmsLinkProfiles(ContextID, nProfiles, Intents, hProfiles, BPC, AdaptationStates, dwFlags);
     if (Lut == NULL) {
diff --git a/src/lcms2.def b/src/lcms2.def
index a60f1b0..b03943c 100644
--- a/src/lcms2.def
+++ b/src/lcms2.def
@@ -364,4 +364,5 @@ cmsMD5alloc                              =   cmsMD5alloc
 cmsMD5finish                             =   cmsMD5finish

 _cmsComputeInterpParams                  =   _cmsComputeInterpParams

 cmsGetToneCurveParams                    =   cmsGetToneCurveParams

+cmsDetectRGBProfileGamma                 =   cmsDetectRGBProfileGamma

 

diff --git a/testbed/testcms2.c b/testbed/testcms2.c
index aad8656..0355fd5 100644
--- a/testbed/testcms2.c
+++ b/testbed/testcms2.c
@@ -1,7 +1,7 @@
 //---------------------------------------------------------------------------------
 //
 //  Little Color Management System
-//  Copyright (c) 1998-2020 Marti Maria Saguer
+//  Copyright (c) 1998-2021 Marti Maria Saguer
 //
 // Permission is hereby granted, free of charge, to any person obtaining
 // a copy of this software and associated documentation files (the "Software"),
@@ -8318,6 +8318,113 @@ int Check_sRGB_Rountrips(void)
     return 1;
 }
 
+static
+cmsHPROFILE createRgbGamma(cmsFloat64Number g)
+{
+    cmsCIExyY       D65 = { 0.3127, 0.3290, 1.0 };
+    cmsCIExyYTRIPLE Rec709Primaries = {
+                                {0.6400, 0.3300, 1.0},
+                                {0.3000, 0.6000, 1.0},
+                                {0.1500, 0.0600, 1.0}
+    };
+    cmsToneCurve* Gamma[3];
+    cmsHPROFILE  hRGB;
+    
+    Gamma[0] = Gamma[1] = Gamma[2] = cmsBuildGamma(0, g);
+    if (Gamma[0] == NULL) return NULL;
+
+    hRGB = cmsCreateRGBProfile(&D65, &Rec709Primaries, Gamma);
+    cmsFreeToneCurve(Gamma[0]);    
+    return hRGB;
+}
+
+
+static
+int CheckGammaSpaceDetection(void)
+{
+    cmsFloat64Number i;
+
+    for (i = 0.5; i < 3; i += 0.1)
+    {                
+        cmsHPROFILE hProfile = createRgbGamma(i);
+
+        cmsFloat64Number gamma = cmsDetectRGBProfileGamma(hProfile, 0.01);
+
+        cmsCloseProfile(hProfile);
+
+        if (fabs(gamma - i) > 0.1)
+        {
+            Fail("Failed profile gamma detection of %f (got %f)", i, gamma);
+            return 0;
+        }
+    }
+
+    return 1;
+}
+
+
+#if 0
+
+// You need to download folowing profilies to execute this test: sRGB-elle-V4-srgbtrc.icc, sRGB-elle-V4-g10.icc
+// The include this line in the checks list:  Check("KInear spaces detection", CheckLinearSpacesOptimization);
+static
+void uint16toFloat(cmsUInt16Number* src, cmsFloat32Number* dst)
+{
+    for (int i = 0; i < 3; i++) {
+        dst[i] = src[i] / 65535.f;
+    }
+}
+
+static
+int CheckLinearSpacesOptimization(void)
+{
+    cmsHPROFILE lcms_sRGB = cmsCreate_sRGBProfile();
+    cmsHPROFILE elle_sRGB = cmsOpenProfileFromFile("sRGB-elle-V4-srgbtrc.icc", "r");
+    cmsHPROFILE elle_linear = cmsOpenProfileFromFile("sRGB-elle-V4-g10.icc", "r");
+    cmsHTRANSFORM transform1 = cmsCreateTransform(elle_sRGB, TYPE_RGB_16, elle_linear, TYPE_RGB_16, INTENT_RELATIVE_COLORIMETRIC, 0);
+    cmsHTRANSFORM transform2 = cmsCreateTransform(elle_linear, TYPE_RGB_16, lcms_sRGB, TYPE_RGB_16, INTENT_RELATIVE_COLORIMETRIC, 0);
+    cmsHTRANSFORM transform2a = cmsCreateTransform(elle_linear, TYPE_RGB_FLT, lcms_sRGB, TYPE_RGB_16, INTENT_RELATIVE_COLORIMETRIC, 0);
+
+    cmsUInt16Number sourceCol[3] = { 43 * 257, 27 * 257, 6 * 257 };
+    cmsUInt16Number linearCol[3] = { 0 };
+    float linearColF[3] = { 0 };
+    cmsUInt16Number finalCol[3] = { 0 };
+    int difR, difG, difB;
+    int difR2, difG2, difB2;
+
+    cmsDoTransform(transform1, sourceCol, linearCol, 1);
+    cmsDoTransform(transform2, linearCol, finalCol, 1);
+
+    cmsCloseProfile(lcms_sRGB); cmsCloseProfile(elle_sRGB); cmsCloseProfile(elle_linear);
+
+
+    difR = (int)sourceCol[0] - finalCol[0];
+    difG = (int)sourceCol[1] - finalCol[1];
+    difB = (int)sourceCol[2] - finalCol[2];
+
+
+    uint16toFloat(linearCol, linearColF);
+    cmsDoTransform(transform2a, linearColF, finalCol, 1);
+
+    difR2 = (int)sourceCol[0] - finalCol[0];
+    difG2 = (int)sourceCol[1] - finalCol[1];
+    difB2 = (int)sourceCol[2] - finalCol[2];
+
+    cmsDeleteTransform(transform1);
+    cmsDeleteTransform(transform2);
+    cmsDeleteTransform(transform2a);
+
+    if (abs(difR2 - difR) > 5 || abs(difG2 - difG) > 5 || abs(difB2 - difB) > 5)
+    {
+        Fail("Linear detection failed");
+        return 0;
+    }
+
+    return 1;
+}
+#endif
+
+
 // --------------------------------------------------------------------------------------------------
 // P E R F O R M A N C E   C H E C K S
 // --------------------------------------------------------------------------------------------------
@@ -9049,7 +9156,7 @@ int main(int argc, char* argv[])
     printf("Installing error logger ... ");
     cmsSetLogErrorHandler(FatalErrorQuit);
     printf("done.\n");
-        
+       
     PrintSupportedIntents();
     
     Check("Base types", CheckBaseTypes);
@@ -9254,6 +9361,7 @@ int main(int argc, char* argv[])
     Check("Proofing intersection", CheckProofingIntersection);
     Check("Empty MLUC", CheckEmptyMLUC);
     Check("sRGB round-trips", Check_sRGB_Rountrips);
+    Check("Gamma space detection", CheckGammaSpaceDetection);
     }
 
     if (DoPluginTests)
diff --git a/utils/delphi/lcms2dll.pas b/utils/delphi/lcms2dll.pas
index 9af7a0d..9368fc9 100644
--- a/utils/delphi/lcms2dll.pas
+++ b/utils/delphi/lcms2dll.pas
@@ -3,7 +3,7 @@
 //---------------------------------------------------------------------------------
 //
 //  Little Color Management System
-//  Copyright (c) 1998-2014 Marti Maria Saguer
+//  Copyright (c) 1998-2021 Marti Maria Saguer
 //
 // Permission is hereby granted, free of charge, to any person obtaining
 // a copy of this software and associated documentation files (the "Software"),
@@ -25,7 +25,7 @@
 //
 //---------------------------------------------------------------------------------
 //
-// Version 2.6
+// Version 2.13
 //
 
 UNIT lcms2dll;
@@ -1659,6 +1659,9 @@ FUNCTION cmsDetectDestinationBlackPoint( BlackPoint: LPcmsCIEXYZ; hProfile: cmsH
 // Estimate total area coverage
 FUNCTION cmsDetectTAC(hProfile: cmsHPROFILE): cmsFloat64Number; StdCall;
 
+// Estimate profile gamma
+FUNCTION cmsDetectRGBProfileGamma(hProfile: cmsHPROFILE): cmsFloat64Number; StdCall;
+
 
 // Poor man's gamut mapping
 FUNCTION  cmsDesaturateLab(Lab: LPcmsCIELab; amax, amin, bmax, bmin: cmsFloat64Number): cmsBool; StdCall;