[Tilecache] Meta Tiled paletted images - PIL issue

[Ivan Mincik]

On Friday 23 October 2009, soatley wrote:
> 
> Ivan Mincik-2 wrote:
> > 
> > On Friday 23 October 2009, you wrote:
> >> I don't think many programs/libraries work with paletted transparency in
> >> PNGs. Nor does PIL. So I'm just writing to confirm that this is a missing
> >> feature of PIL.
> >> Tibor
> > 
> > No solution found also after writing to PIL mailing list, so we can not
> > use nice optimized images produced by UMN Mapserver.
> > We decided to produce RGBA images from Mapserver and write a "patch"  to
> > Tilecache to optimize images just after creation using external tools like
> > pngnq of optipng.
> > 
> > Ivan 
> > 
> 
> We use OptiPNG here and it works pretty good, but unfortunately, it does
> take a fair amount of time to run.  On some of our larger layers (ortho) it
> saves a lot of space.
> 
> Shawn
> 

Since now we used pngnq for postprocessing of Tilecache disk cache. But, in case of constant cache updates containing many milions of images, we have found a pain in detection, which image is already optimized, which one not. Therefore I think, it should be better to process every image just after saving to disk.

Ivan
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