Added option to TIFF handler for specifying the photometric interpretation.

Added option wxIMAGE_OPTION_TIFF_PHOTOMETRIC for reading and writing TIFF images. This is mostly for being able to distinguish between PHOTOMETRIC_MINISBLACK (chocolate flavour) and PHOTOMETRIC_MINISWHITE (vanilla) as currently the flavour used was fixed. It applies to greyscale as well as black and white images. Added unit tests to verify the written photometric value.

Also see #13194.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@68785 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

diff --git a/include/wx/imagtiff.h b/include/wx/imagtiff.h
index 19d1cf1c73c68689eff8a489dc400aaab40c53a2..f1f4f74c6f0a5372118aedd58ab93cf63a123cc5 100644 (file)
--- a/include/wx/imagtiff.h
+++ b/include/wx/imagtiff.h
@@ -25,6 +25,7 @@
 #define wxIMAGE_OPTION_TIFF_BITSPERSAMPLE               wxString(wxT("BitsPerSample"))
 #define wxIMAGE_OPTION_TIFF_SAMPLESPERPIXEL             wxString(wxT("SamplesPerPixel"))
 #define wxIMAGE_OPTION_TIFF_COMPRESSION                 wxString(wxT("Compression"))
+#define wxIMAGE_OPTION_TIFF_PHOTOMETRIC                 wxString(wxT("Photometric"))
 #define wxIMAGE_OPTION_TIFF_IMAGEDESCRIPTOR             wxString(wxT("ImageDescriptor"))
 
 // for backwards compatibility

diff --git a/src/common/imagtiff.cpp b/src/common/imagtiff.cpp
index d8d449c5cff755d596a0e4db737990f9841c9dd2..e4458e3f9869c7546f23eb5b582b5fc4a2667c9b 100644 (file)
--- a/src/common/imagtiff.cpp
+++ b/src/common/imagtiff.cpp
@@ -437,6 +437,8 @@ bool wxTIFFHandler::LoadFile( wxImage *image, wxInputStream& stream, bool verbos
     }
 
 
+    image->SetOption(wxIMAGE_OPTION_TIFF_PHOTOMETRIC, photometric);
+
     uint16 spp, bps, compression;
     /*
     Read some baseline TIFF tags which helps when re-saving a TIFF
@@ -603,6 +605,27 @@ bool wxTIFFHandler::SaveFile( wxImage *image, wxOutputStream& stream, bool verbo
         spp = 1;
     }
 
+    int photometric = PHOTOMETRIC_RGB;
+
+    if ( image->HasOption(wxIMAGE_OPTION_TIFF_PHOTOMETRIC) )
+    {
+        photometric = image->GetOptionInt(wxIMAGE_OPTION_TIFF_PHOTOMETRIC);
+        if (photometric == PHOTOMETRIC_MINISWHITE
+            || photometric == PHOTOMETRIC_MINISBLACK)
+        {
+            // either b/w or greyscale
+            spp = 1;
+        }
+    }
+    else if (spp == 1)
+    {
+        photometric = PHOTOMETRIC_MINISBLACK;
+    }
+
+    const bool isColouredImage = (spp > 1)
+        && (photometric != PHOTOMETRIC_MINISWHITE)
+        && (photometric != PHOTOMETRIC_MINISBLACK);
+
     int compression = image->GetOptionInt(wxIMAGE_OPTION_TIFF_COMPRESSION);
     if ( !compression )
     {
@@ -615,8 +638,7 @@ bool wxTIFFHandler::SaveFile( wxImage *image, wxOutputStream& stream, bool verbo
 
     TIFFSetField(tif, TIFFTAG_SAMPLESPERPIXEL, spp);
     TIFFSetField(tif, TIFFTAG_BITSPERSAMPLE, bps);
-    TIFFSetField(tif, TIFFTAG_PHOTOMETRIC, spp*bps == 1 ? PHOTOMETRIC_MINISBLACK
-                                                        : PHOTOMETRIC_RGB);
+    TIFFSetField(tif, TIFFTAG_PHOTOMETRIC, photometric);
     TIFFSetField(tif, TIFFTAG_COMPRESSION, compression);
 
     // scanlinesize if determined by spp and bps
@@ -627,7 +649,7 @@ bool wxTIFFHandler::SaveFile( wxImage *image, wxOutputStream& stream, bool verbo
 
     unsigned char *buf;
 
-    if (TIFFScanlineSize(tif) > linebytes || (spp * bps < 24))
+    if (TIFFScanlineSize(tif) > linebytes || !isColouredImage)
     {
         buf = (unsigned char *)_TIFFmalloc(TIFFScanlineSize(tif));
         if (!buf)
@@ -649,12 +671,13 @@ bool wxTIFFHandler::SaveFile( wxImage *image, wxOutputStream& stream, bool verbo
 
     TIFFSetField(tif, TIFFTAG_ROWSPERSTRIP,TIFFDefaultStripSize(tif, (uint32) -1));
 
+    const bool minIsWhite = (photometric == PHOTOMETRIC_MINISWHITE);
     unsigned char *ptr = image->GetData();
     for ( int row = 0; row < image->GetHeight(); row++ )
     {
         if ( buf )
         {
-            if ( spp * bps > 1 )
+            if (isColouredImage)
             {
                 // color image
                 memcpy(buf, ptr, image->GetWidth());
@@ -663,7 +686,13 @@ bool wxTIFFHandler::SaveFile( wxImage *image, wxOutputStream& stream, bool verbo
             {
                 for ( int column = 0; column < linebytes; column++ )
                 {
-                    buf[column] = ptr[column*3 + 1];
+                    uint8 value = ptr[column*3 + 1];
+                    if (minIsWhite)
+                    {
+                        value = 255 - value;
+                    }
+
+                    buf[column] = value;
                 }
             }
             else // black and white image
@@ -673,7 +702,7 @@ bool wxTIFFHandler::SaveFile( wxImage *image, wxOutputStream& stream, bool verbo
                     uint8 reverse = 0;
                     for ( int bp = 0; bp < 8; bp++ )
                     {
-                        if ( ptr[column*24 + bp*3 + 1] > 127 )
+                        if ( (ptr[column*24 + bp*3 + 1] <=127) == minIsWhite )
                         {
                             // check only green as this is sufficient
                             reverse = (uint8)(reverse | 128 >> bp);

diff --git a/tests/image/image.cpp b/tests/image/image.cpp
index 9135e433b916fca61ebd7288a22f9ab88d0b0568..0350dcbfa9bd94a100473c276501898c8b4d1b38 100644 (file)
--- a/tests/image/image.cpp
+++ b/tests/image/image.cpp
@@ -1116,6 +1116,8 @@ void ImageTestCase::SaveTIFF()
 {
     TestTIFFImage(wxIMAGE_OPTION_TIFF_BITSPERSAMPLE, 1);
     TestTIFFImage(wxIMAGE_OPTION_TIFF_SAMPLESPERPIXEL, 1);
+    TestTIFFImage(wxIMAGE_OPTION_TIFF_PHOTOMETRIC, 0/*PHOTOMETRIC_MINISWHITE*/);
+    TestTIFFImage(wxIMAGE_OPTION_TIFF_PHOTOMETRIC, 1/*PHOTOMETRIC_MINISBLACK*/);
 }
 
 void ImageTestCase::SaveAnimatedGIF()