diff --git a/code/nel/tools/3d/panoply_maker/panoply_maker.cpp b/code/nel/tools/3d/panoply_maker/panoply_maker.cpp
index 70e3b979e..dc0ace2a3 100644
--- a/code/nel/tools/3d/panoply_maker/panoply_maker.cpp
+++ b/code/nel/tools/3d/panoply_maker/panoply_maker.cpp
@@ -791,41 +791,49 @@ static void BuildColoredVersionForOneBitmap(const CBuildInfo &bi, const std::str
 						throw NLMISC::Exception("Failed to load mask");
 					}
 
-					// masks can be converted to grayscale files
-					if (bi.OptimizeTextures > 0 && maskDepth > 8)
+					// convert color mask to grayscale (red is the new gray value)
+					if (li.Mask.getPixelFormat() == CBitmap::RGBA)
 					{
-						if (!li.Mask.isGrayscale())
+						// display a warning if checks enabled
+						if (bi.OptimizeTextures > 0 && !li.Mask.isGrayscale())
 						{
 							nlwarning("Mask %s is using colors, results may by incorrect! Use OptimizeTextures = 2 to fix it.", maskFileName.c_str());
 						}
 
-						if (bi.OptimizeTextures > 1)
-						{
-							// get a pointer on original data
-							uint32 size = li.Mask.getPixels().size();
-							uint32 *data = (uint32*)li.Mask.getPixels().getPtr();
-							uint32 *endData = (uint32*)((uint8*)data + size);
+						// get a pointer on original data
+						uint32 size = li.Mask.getPixels().size();
+						uint32 *data = (uint32*)li.Mask.getPixels().getPtr();
+						uint32 *endData = (uint32*)((uint8*)data + size);
 
-							NLMISC::CRGBA *color = NULL;
+						NLMISC::CRGBA *color = NULL;
 
-							// process all pixels
-							while(data < endData)
-							{
-								color = (NLMISC::CRGBA*)data;
+						// process all pixels
+						while(data < endData)
+						{
+							color = (NLMISC::CRGBA*)data;
 
-								// copy red value to green and blue,
-								// because only red is used for mask
-								color->B = color->G = color->R;
+							// copy red value to green and blue,
+							// because only red is used for mask
+							color->B = color->G = color->R;
 
-								// make opaque
-								color->A = 255;
+							// make opaque
+							color->A = 255;
 
-								++data;
-							}
+							++data;
+						}
+					}
 
-							// convert image to real grayscale
-							li.Mask.convertToType(NLMISC::CBitmap::Luminance);
+					// convert image to real grayscale
+					if (li.Mask.PixelFormat != NLMISC::CBitmap::Luminance)
+					{
+						li.Mask.convertToType(NLMISC::CBitmap::Luminance);
+					}
 
+					// masks can be converted to grayscale files
+					if (bi.OptimizeTextures > 0 && maskDepth > 8)
+					{
+						if (bi.OptimizeTextures > 1)
+						{
 							NLMISC::COFile os;
 
 							if (os.open(maskFileName))
@@ -855,11 +863,6 @@ static void BuildColoredVersionForOneBitmap(const CBuildInfo &bi, const std::str
 						}
 					}
 
-					if (li.Mask.PixelFormat != NLMISC::CBitmap::Luminance)
-					{
-						li.Mask.convertToType(NLMISC::CBitmap::Luminance);
-					}
-
 					/// make sure the mask has the same size
 					if (li.Mask.getWidth() != srcBitmap.getWidth()
 						|| li.Mask.getHeight() != srcBitmap.getHeight())