This argument should actually say "Do not store premultiplied channel
values", which is what the TIFF spec calls "Unassociated alpha" (vs.
"associated alpha" when values are stored premultiplied by alpha).
Now I can see where the current description is coming from, which is
that any color with alpha 0 (totally masked) ends up as RGBA value (0,
0, 0, 0), in other words, the color information is completely lost. Yet
this label is not very helpful to understand what the checkbox really
does. I decided to not just change it altogether as people would have
gotten used to this for years, but at least adding completary
information in API and tooltip in GUI.
...export dialogs
Remove the "Advanced" expanders from the PNG and TIFF export
dialogs. This does not reorder anything in the GUI yet, the
dialogs are still ugly.
Based on original patches from Hartmut Kuhse and modified
by Michael Natterer. Changes include:
- remove libexif dependency and add a hard dependency on gexiv2
- typedef GExiv2Metadata to GimpMetadata to avoid having to
include gexiv2 globally
- add basic GimpMetadata handling functions to libgimpbase
- add image and image file specific metadata functions to libgimp,
including the exif orientation image rotate dialog
- port plug-ins to use the new APIs
- port file-tiff-save's UI to GtkBuilder
- add new plug-in "metadata" to view the image's metadata
- keep metadata around as GimpImage member in the core
- update the image's metadata on image size, resolution and precision
changes
- obsolete the old metadata parasites
- migrate the old parasites to new GimpMetadata object on XCF load
