[gimp/wip/wormnest/windows-tiff-delete: 59/61] libgimp: set subfiletype to FILETYPE_REDUCEDIMAGE when saving EXIF thumbnails.

[Jacob Boerema <jboerema src gnome org>]

commit d577e516c5608df21abafdce39d38e1bd7c4adb5
Author: Jacob Boerema <jgboerema gmail com>
Date:   Mon Aug 16 13:34:36 2021 -0400

    libgimp: set subfiletype to FILETYPE_REDUCEDIMAGE when saving EXIF thumbnails.
    
    Setting the type to reduced image for a thumbnail makes it easier when
    loading TIFF images to recognize a page as a thumbnail.

 libgimp/gimpimagemetadata-save.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
---
diff --git a/libgimp/gimpimagemetadata-save.c b/libgimp/gimpimagemetadata-save.c
index ff9ba52fab..ff2ae4e57a 100644
--- a/libgimp/gimpimagemetadata-save.c
+++ b/libgimp/gimpimagemetadata-save.c
@@ -633,7 +633,10 @@ gimp_image_metadata_save_finish (GimpImage              *image,
                                           "3");
           gexiv2_metadata_set_tag_string (new_g2metadata,
                                           "Exif.Thumbnail.PhotometricInterpretation",
-                                          "6");
+                                          "6"); /* old jpeg */
+          gexiv2_metadata_set_tag_string (new_g2metadata,
+                                          "Exif.Thumbnail.NewSubfileType",
+                                          "1"); /* reduced resolution image */
 
           g_free (thumb_buffer);
         }