[Tilecache] bad quality with 8bit AGG PNG images and metaTile=true

[Ivan Mincik]

Thanks for the reply. Using the pngnq is second possibility.
The problem is that 95 % of layers does not contain labels, so I can
use native 8bit  Mapserver/Tilecache rendering. I would prefer if I
could use it for the rest 5 percent.
Do You thing that PIL can spoil the image when cutting it in to tails,
or can it be some problem with Tilecache ?

Ivan


On Thu, Mar 5, 2009 at 7:11 PM, Guillaume Sueur
<no-reply at neogeo-online.net> wrote:
> I would suggest you output 24bits PNG and have them reduced to 8bits
> overnight with the excellent pngnq lib. (http://pngnq.sourceforge.net/)
>
>
> Ivan Mincik a écrit :
>> I am using UMN Mapserver WMS server version 5.2.1 which is rendering PNG images using AGG backend. They are reduced to 8bit.
>> When the Tilecache option "metaTile" is set to false, I have nice looking tiles. For the layers containing  labeIs I need to use option "metaTile=true".
>>
>> Using the option "metaTile=true" for 8bit AGG PNG images gets visibly worse looking results. Can it be some problem with combination PIL and reduced 8bit images ?
>>
>> Tilecache version is 2.03-1.
>>
>> MapFile options are:
>>
>>        OUTPUTFORMAT
>>                 NAME "PNG_AGGAQ"
>>                 DRIVER "AGG/PNG"
>>                 MIMETYPE "image/png"
>>                 IMAGEMODE RGBA
>>                 FORMATOPTION "QUANTIZE_FORCE=ON"
>>                 FORMATOPTION "QUANTIZE_DITHER=OFF"
>>                 FORMATOPTION "QUANTIZE_COLORS=256"
>>                 FORMATOPTION  "INTERLACE=OFF"
>>                 TRANSPARENT ON
>>         END
>>
>> Tilecache config:
>> [layername]
>> type=WMSLayer
>> url=http://server/cgi-bin/mapserv?map=map.map&transparent=true
>> layers=layername
>> extension=png
>> debug=on
>> metaTile=true
>> extent_type=loose
>> srs=EPSG:2065
>> bbox=-273393.437500, -1256155.375000, -255811.593750, -1227652.250000
>> resolutions=176.38879363894028529, 88.19439681947014265, 35.27775872778806132, 17.63887936389403066, 8.81943968194701533, 3.52777587277880578, 1.76388793638940289, 0.88194396819470144, 0.35277758727788061, 0.17638879363894031
>>
>>
>> Thanks
>> Ivan
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>>
>>
>