GNOME Bugzilla – Bug 619843
Saving as 32bit bitmap ignores alpha channel
Last modified: 2010-06-01 07:37:46 UTC
When saving as a 32bit bmp it ignores the alpha channel, after doing a hexdump i found that the alpha component is set to 0xff throughout the image even though some of it was transparent before saving.
Closing as duplicate to 573090 which is regarding the same topic, although it's not a pure duplicate. In short: Please provide a patch. *** This bug has been marked as a duplicate of bug 573090 ***
And repeating what I said in bug #573090: 32-bit bmp files with "BI_RGB" compression are underspecified. The "extra" byte of each pixel is interpreted as an alpha channel in some software, but ignored in other software. For portability between applications, you should avoid this format.