[OSM-dev] Optimising PNGs / Colour reduction

[Grant Slater]

Robert (Jamie) Munro wrote:
> Why are we compressing the image as a 24 bit PNG, then uncompressing it
> inside the convert command, reducing the colour pallette and compressing
> again? Can't we save as an uncompressed format, and only make it into a
> PNG once?
>   

The original script was a quick hack I understand, the code is not clean 
but works. Patches accepted. :-)

A post process is required because Mapnik (currently) can only save in 
24 bit. mod_tile also has a post process step.

Grant