http://bugs.winehq.org/show_bug.cgi?id=31557
--- Comment #35 from Dmitry Timoshkov dmitry@baikal.ru 2013-08-14 19:24:04 CDT --- (In reply to comment #33)
Oh, actually that's pretty much the same as Samuel's last patch, which was a partial revert. The code looks right to me (a WIC encoder can set a different pixel format from the one requested, in which case it's up to the caller to convert the image data to that format), so I wonder why Dmitry's patch removed it.
If I recall correctly removed code was causing test failures.