[eog] EogMetadataReaderJpg: Disable color profile generation from Exif tags

[Felix Riemann <friemann src gnome org>]

commit 9eceea6e8f21bdeb731a799e14d6ac562057ae18
Author: Felix Riemann <friemann gnome org>
Date:   Sat Feb 3 14:36:22 2018 +0100

    EogMetadataReaderJpg: Disable color profile generation from Exif tags
    
    The code's currently not really error safe (divides-by-zero) and image
    editing apps like GIMP don't seem to take these tags into account either
    and just assume sRGB in that case. So, it's currently doubtful if these
    generated color profile are actually helping.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=792770

 src/eog-metadata-reader-jpg.c |   11 +++++++++++
 1 files changed, 11 insertions(+), 0 deletions(-)
---
diff --git a/src/eog-metadata-reader-jpg.c b/src/eog-metadata-reader-jpg.c
index b958203..3b3f5a3 100644
--- a/src/eog-metadata-reader-jpg.c
+++ b/src/eog-metadata-reader-jpg.c
@@ -51,6 +51,10 @@ typedef enum {
        EJA_OTHER
 } EogJpegApp1Type;
 
+/* This enables color profile generation from Exif valus. However it's
+ * uncertain how well maintained that information is since applications like
+ * GIMP ignore this data. */
+#define EOG_METADATA_READER_JPG_GEN_PROFILE_FROM_EXIF_VALUES 0
 
 #define EOG_JPEG_MARKER_START   0xFF
 #define EOG_JPEG_MARKER_SOI     0xD8
@@ -541,6 +545,11 @@ eog_metadata_reader_jpg_get_icc_profile (EogMetadataReaderJpg *emr)
                color_space = exif_get_short (entry->data, o);
 
                switch (color_space) {
+#if EOG_METADATA_READER_JPG_GEN_PROFILE_FROM_EXIF_VALUES == 0
+               case 0xFFFF:
+                       eog_debug_message (DEBUG_LCMS, "JPEG is uncalibrated. "
+                                                      "Fallback to sRGB.");
+#endif
                case 1:
                        eog_debug_message (DEBUG_LCMS, "JPEG is sRGB");
 
@@ -554,6 +563,7 @@ eog_metadata_reader_jpg_get_icc_profile (EogMetadataReaderJpg *emr)
                        //profile = cmsCreate_Adobe1998Profile ();
 
                        break;
+#if EOG_METADATA_READER_JPG_GEN_PROFILE_FROM_EXIF_VALUES != 0
                case 0xFFFF:
                        {
                        cmsCIExyY whitepoint;
@@ -625,6 +635,7 @@ eog_metadata_reader_jpg_get_icc_profile (EogMetadataReaderJpg *emr)
 
                        break;
                        }
+#endif
                }
 
                exif_data_unref (exif);