Re: [Gimp-user] how to preserve semi-transparency when converting to indexed

[Michael Schumacher <schumaml gmx de>]

On 02.07.2012 02:49, temp-user wrote:
> > I used to convert them to indexed so their size would be reduced. Since I installed a new version, the 
> > semi-transparency is cut off and I have just plain black on transparent background as if there were no 
> > antialiasing, very ugly.
>
> I too used to use the ability to create indexed color pngs with semi-ransparent pixels.
> this ability seems to have been either removed, lost or broken in the more recent release of gimp.
>
> the png format can support it but it looks like gimp just does indexed color conversion  in a very GIF-like 
> way.

GIMP has no support for this - there's an ancient bug report about 
allowing real alpha channels in indexed files, see 
https://bugzilla.gnome.org/show_bug.cgi?id=86627

The PNG plug-in should load the alpha channel from an indexed PNG file, 
but you'll have to et the mode to RGB in order to make use of it.


HTH,
Michael