Changeset 14770

Timestamp:

06/26/08 15:50:06 (5 months ago)

Author:

rouault

Message:

JPEG driver : add support for reading images in CMYK and YCbCrK color spaces (#2443)

Files:

• trunk/gdal/frmts/jpeg/frmt_jpeg.html (modified) (2 diffs)
• trunk/gdal/frmts/jpeg/jpgdataset.cpp (modified) (9 diffs)

trunk/gdal/frmts/jpeg/frmt_jpeg.html

@@ -12 +12 @@
-band (RGB) datasets with Byte valued bands.<p>
-
+The driver will automatically convert images whose color space is YCbCr, CMYK or
+YCbCrK to RGB, unless GDAL_JPEG_TO_RGB is set to NO (YES is the default). When
+color space translation to RGB is done, the source color space is indicated in the
+SOURCE_COLOR_SPACE metedata of the IMAGE_STRUCTURE domain.<p>
+
-There is currently no support for georeferencing information or metadata for
-JPEG files. But if an ESRI world file exists with the .jgw, .jpgw/.jpegw or .wld suffixes,
-it will be read and used to establish the geotransform for the image. Overviews
-can be built for JPEG files as an external .ovr file.<p>
+
+The driver also supports the "zlib compressed mask appended to the file" approach
+used by a few data providers to add a bitmask to identify pixels that are not valid data.
+See <a href="http://trac.osgeo.org/gdal/wiki/rfc15_nodatabitmask">RFC 15</a> for further details.<p>
-
-The GDAL JPEG Driver is built using the Independent JPEG Group's jpeg
@@ -24 +33 @@
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-JPEG files are created using the "JPEG" driver code.  Only Byte band types
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-<ul>

trunk/gdal/frmts/jpeg/jpgdataset.cpp

@@ -114 +114 @@
-    int    nCMaskSize;
-
+    J_COLOR_SPACE eGDALColorSpace;   /* color space exposed by GDAL. Not necessarily the in_color_space nor */
+                                     /* the out_color_space of JPEG library */
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-  public:
-                 JPGDataset();
@@ -740 +743 @@
-                       nXSize );
-#else
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-#endif
-    }
@@ -750 +789 @@
-/*      Forceably load the other bands associated with this scanline.   */
-/* -------------------------------------------------------------------- */
-poGDS->GetRasterCount() == 3 && 
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-    {
-        GDALRasterBlock *poBlock;
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-    return CE_None;
@@ -773 +813 @@
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-nBands == 1
+eGDALColorSpace == JCS_GRAYSCALE
-        return GCI_GrayIndex;
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-}
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@@ -858 +935 @@
-    pabyCMask = NULL;
-    nCMaskSize = 0;
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+    eGDALColorSpace = JCS_UNKNOWN;
-}
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@@ -911 +990 @@
-
-    if( pabyScanline == NULL )
+    {
+        int nJPEGBands = 0;
+        switch(sDInfo.out_color_space)
+        {
+            case JCS_GRAYSCALE:
+                nJPEGBands = 1;
+                break;
+            case JCS_RGB:
+            case JCS_YCbCr:
+                nJPEGBands = 3;
+                break;
+            case JCS_CMYK:
+            case JCS_YCCK:
+                nJPEGBands = 4;
+                break;
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+            default:
+                CPLAssert(0);
+        }
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-        pabyScanline = (GByte *)
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-    // setup to trap a fatal error.
@@ -1115 +1215 @@
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+    J_COLOR_SPACE colorSpace = sDInfo.out_color_space;
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-    jpeg_abort_decompress( &sDInfo );
-    jpeg_destroy_decompress( &sDInfo );
@@ -1132 +1234 @@
-    jpeg_read_header( &sDInfo, TRUE );
-    
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-    nLoadedScanline = -1;
-    jpeg_start_decompress( &sDInfo );
@@ -1457 +1556 @@
-    poDS->nRasterYSize = poDS->sDInfo.image_height;
-
+    poDS->sDInfo.out_color_space = poDS->sDInfo.jpeg_color_space;
+    poDS->eGDALColorSpace = poDS->sDInfo.jpeg_color_space;
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-    if( poDS->sDInfo.jpeg_color_space == JCS_GRAYSCALE )
-    {
-        poDS->nBands = 1;
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-    {
-        poDS->nBands = 3;
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-    }
-    else