[mapserver-users] Quantize and 8bit/1bit PNG problem

[paalkr]

Hi!

Could I please ask for a comment on this issue from one of the developers?



paalkr wrote:
> 
> Hi!
> 
> I have the following output format defined in my mapfile (MapServer
> 5.4.2):
> 
>    OUTPUTFORMAT
>       NAME "png8bit"
>       DRIVER "AGG/PNG"
>       MIMETYPE "image/png"
>       EXTENSION "png"
>       FORMATOPTION "QUANTIZE_FORCE=ON"
>       FORMATOPTION "QUANTIZE_COLORS=256"
>       FORMATOPTION "QUANTIZE_NEW=ON"
>       FORMATOPTION INTERLACE=OFF
>    END
> 
> This works very well most of the time, even transparency. But in
> situations where the GetMap request don't contain any data at all
> (returned image should be total transparent) the resulting PNG is 1bit in
> stead of 8bits. If the produced image does contain some data the produced
> image i 8bits, with correctly rendered transparency where there are no
> data.
> 
> This behavior are specially troublesome when building a tile cache because
> there are a lot of this request without any valid data. In almost all
> applications I guess that this issue wouldn't do any harm, but we uses
> Bing Maps for some projects and Bing Maps can't handle 1bit PNGs.
> 
> What can be done to overcome this issue? 
> 
> Regards,
> Pål Kristensen
> 
> 


-----

Regards,
Pål Kristensen
-- 
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