[mapserver-users] AGG OUTPUTFORMAT Question

[Paul Spencer]

Steve,

  I use this OUTPUTFORMAT

OUTPUTFORMAT
   NAME png
   MIMETYPE "image/png"
   DRIVER "AGG/PNG"
   EXTENSION "png"
   IMAGEMODE "RGB"
   FORMATOPTION "PALETTE_FORCE=TRUE"
   FORMATOPTION "PALETTE=/path/to/palette.txt"
END

We've had good results with this in terms of colours - once you  
identify the main colours you want to keep from the map file and any  
images in your palette.txt file, GD seems to do a pretty reasonable  
job of filling in the antialiasing colours

I'm not sure the extra quality that Thomas mentioned would be  
noticeable, but I haven't tried it.  I think that it might be worth  
running pngnq on tiles as well - not to reduce the palette but to  
reduce the tile size, but I'm not sure on that.

Cheers

Paul

On 17-Dec-08, at 2:38 PM, Stephen Woodbridge wrote:

> Hi Thomas, et al,
>
> I need to generate tiles using AGG output and need them to be 8 bit  
> png images.
>
> http://mapserver.gis.umn.edu/docs/howto/agg-rendering-specifics
>
> Does not make it clear if any of the formats shown are 8 bit png  
> images and it does not note the use of:
>
>    FORMATOPTION "PALETTE_FORCE=TRUE"
>    FORMATOPTION "PALETTE=/u/data/maps/palette-agg.txt"
>
> What is the proper way to set up OUTPUTFORMAT to use AGG to get the  
> best quality 8 bit output. I think I need to use the PALETTE*  
> options to control color shifts in adjacent tiles.
>
> I would be happy to add a comment to the above link with this  
> additional info.
>
> Best regards,
>  -Steve W
> _______________________________________________
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> mapserver-users at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/mapserver-users


__________________________________________

    Paul Spencer
    Chief Technology Officer
    DM Solutions Group Inc
    http://research.dmsolutions.ca/