1 Reply Latest reply on Apr 29, 2006 10:38 AM by Newsgroup_User

    Alpha channel in GIFs

    tokaplan Level 1
      Is it possible to export a transparency value (8 bits) from a GIF frame onto a separate channel so that it could be easily loaded by DirectX utility functions? I've tried everything, but the RGBA value in a resulting file seems to always have 255 in A channel, while RGB codes color correcly.
      Thank you
        • 1. Re: Alpha channel in GIFs
          Level 7
          On Sat, 29 Apr 2006 13:49:45 +0400, tokaplan
          <webforumsuser@macromedia.com> wrote:

          > Is it possible to export a transparency value (8 bits) from a GIF frame
          > onto a
          > separate channel so that it could be easily loaded by DirectX utility
          > functions? I've tried everything, but the RGBA value in a resulting file
          > seems
          > to always have 255 in A channel, while RGB codes color correcly.
          > Thank you

          GIF files do not have alpha channel at all. Transparency in GIF files is
          achieved by declaring one of palette entry ("color") transparent. So one
          palette entry is interpreted as "fully transparent", all the others as
          "fully opaque". There is no "partial transparency" and so no separate "A"
          transparency channel to hold it. I have no idea what tool and how you are
          trying to use but looking for transparency value, 8 bits, in GIF files is
          wrong idea. Look for particular palette entry instead, and of course,
          forget about 8 bits.

          --
          Ilya Razmanov
          http://photoshop.msk.ru - Photoshop plug-in filters