[mapserver-users] LA raster images in MapServer and MapCache

[David Hoese]

Hi,

I have some geotiffs that are grayscale with an alpha band (Luminance + 
Alpha). MapServer seems to be able to read and understand the 
transparency fine, but I'm having trouble figuring out if it is possible 
to produce a gray+alpha PNG version of these by configuring 
OUTPUTFORMAT. My end goal is to reduce the size of the images cached by 
MapCache by having my MapServer WMS produce gray+alpha PNGs.

Does the builtin AGG/PNG driver in MapServer support this format? Like I 
said, I couldn't figure it out based on the documentation. Assuming 
GDAL/PNG can do it, does anyone have an idea on the performance penalty? 
The MapServer documentation mentions that AGG/PNG is generally more 
efficient.

Thanks for any info. I'll keep playing around.

Dave