forced palette for RGBA images

Daniel Morissette dmorissette at MAPGEARS.COM
Fri Dec 7 16:46:20 EST 2007

Sounds like a cool feature. We'd need to make sure it is well documented 
and not just hidden in the source. A short RFC or ticket for this maybe?


thomas bonfort wrote:
> hello list,
> I've added the possiblity to force a color palette for RGBA images. As
> gd does not support this kind of images, I had to resort to directly
> use libpng functions for the actual saving of the file.
> The steps needed to actually use this would be:
> - create a 24 bit rgba image representative of a typical image that
> would be produced
> - use an external program to create an rgba paletted version of the
> image (pngquant, pngnq, photoshop...)
> - extract the palette from the created image and save the values in
> the form r,g,b,a in a text file (one per line)
> - use palette_force and palette formatoptions in the outputformat block.
> This is rather complicated, but usefull on production setups to
> minimize image size when using clients that overlay layers (eg
> openlayers).
> There are still a few quirks I'd have to work on before the code is
> robust enough for inclusion in the trunk, so I'd like to know if this
> is a feature we'd definitely like to have before putting too much
> effort into that.
> cheers,
> thomas

Daniel Morissette

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