Trilinear interpolation (II)

1 files changed, 27 insertions, 0 deletions

diff --git a/src/cmsio1.c b/src/cmsio1.c
index 91cf06d..c367627 100644
--- a/src/cmsio1.c
+++ b/src/cmsio1.c
@@ -386,6 +386,27 @@ cmsPipeline* BuildRGBOutputMatrixShaper(cmsHPROFILE hProfile)
     return Lut;
 }
 
+
+// Change CLUT interpolation to trilinear
+static
+void ChangeInterpolationToTrilinear(cmsPipeline* Lut)
+{
+    cmsStage* Stage;
+
+    for (Stage = cmsPipelineGetPtrToFirstStage(Lut);
+        Stage != NULL;
+        Stage = cmsStageNext(Stage)) {
+
+            if (cmsStageType(Stage) == cmsSigCLutElemType) {
+
+                _cmsStageCLutData* CLUT = (_cmsStageCLutData*) Stage ->Data;
+
+                CLUT ->Params->dwFlags |= CMS_LERP_FLAGS_TRILINEAR;
+                _cmsSetInterpolationRoutine(CLUT ->Params);
+            }
+    }
+}
+
 // Create an output MPE LUT from agiven profile. Version mismatches are handled here
 cmsPipeline* _cmsReadOutputLUT(cmsHPROFILE hProfile, int Intent)
 {
@@ -419,6 +440,12 @@ cmsPipeline* _cmsReadOutputLUT(cmsHPROFILE hProfile, int Intent)
         // The profile owns the Lut, so we need to copy it
         Lut = cmsPipelineDup(Lut);
 
+        // Now it is time for a controversial stuff. I found that for 3D LUTS using 
+        // Lab used as indexer space,  trilinear interpolation should be used 
+        
+		if (cmsGetPCS(hProfile) == cmsSigLabData)
+                             ChangeInterpolationToTrilinear(Lut);		
+
         // We need to adjust data only for Lab and Lut16 type
         if (OriginalType != cmsSigLut16Type || cmsGetPCS(hProfile) != cmsSigLabData) 
             return Lut;