Created attachment 135869 [details] [review]
Test reading and writing compression

Created attachment 135870 [details] [review]
Implement reading and writing "compression" option

This change implements a "compression" option when loading or saving TIFF that is based on the TIFF compression tag.

I don't really see the point in exposing the compression option on loaded images.
Other than that, looks reasonable. 

The 'compression' parameter should be mentioned in the relevant doc comments in gdk-pixbuf-io.c

Created attachment 136275 [details] [review]
Implement "compression", with documentation

I added documentation to gdk_pixbuf_save.

I find it very useful to read the compression because for a concrete example, monochromatic images can be compressed with codec 3, FAX encoding, which doesn't work with coloured images. So if I want to load, and later save such a file I want to be able to re-encode it with its original codec.

(In reply to comment #3)
> I don't really see the point in exposing the compression option on loaded
> images.

Well, I do. GdkPixbuf should allow an application to preserve the compression format when loading and saving an image file. For this, the app needs to be able to read-out if an image was compressed in the first place and how.

Comment on attachment 136275 [details] [review]
Implement "compression", with documentation

Looks good to commit.

Pushed to master.