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Re: [Geotools-devel] [Geoserver-devel] Strange problems with png8 image format and transparency=true requests
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From: Andrea A. <aa...@op...> - 2010-05-19 07:14:39
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Frank Gasdorf ha scritto: > Hi, > > First : Sorry for cross-posting, but I have no idea where the problem > occurs and geoserver is based on geotools. > > After the fix of bug UDIG-1650 > <http://jira.codehaus.org/browse/UDIG-1650> (transparency and image > format png8) the labels of rendered features are ugly. What I've done: > > - checked out response from geoserver 2.0.x with image format png8 and > transparency > png (attachment transpatent-png.png): > http://localhost:8092/geoserver/wms?bbox=-130,24,-66,50&styles=&Format=image/png&request=GetMap&layers=utm_grp&width=550&height=250&srs=EPSG:4326&transparency=true > <http://localhost:8092/geoserver/wms?bbox=-130,24,-66,50&styles=&Format=image/png&request=GetMap&layers=utm_grp&width=550&height=250&srs=EPSG:4326&transparency=true> > png8 (attachment transpatent-png8.png): > http://localhost:8092/geoserver/wms?bbox=-130,24,-66,50&styles=&Format=image/png8&request=GetMap&layers=utm_grp&width=550&height=250&srs=EPSG:4326&transparency=true > <http://localhost:8092/geoserver/wms?bbox=-130,24,-66,50&styles=&Format=image/png8&request=GetMap&layers=utm_grp&width=550&height=250&srs=EPSG:4326&transparency=true> > > What is the reason of this kind of ugly labels if transparency is set to > true? If the request is without the transparency parameter both pictures > are equal and looking like wms.png. Do you have any suggestions why this > happens? > > Is it probably an imageIO problem, a renderer option (anti-aliasing or > something like that) problem? I already answered you on the uDig lists. Quoting: ------------------------------------------------------------------------ Labels use antialising heavily, when we do color reduction to 256 colors that will suffer inevitably, especially with transparent output. There is nothing easy that can be done for that unfortunately, we'd need a color reduction algorithm that supports alpha in the palette, something that an open source project, pngnq, does, but it's not trivial at all to port over. I'd estimate it would take 3-5 days of work for a developer that knows _very_ well its way in the raster data manipulation algorithms and will probably result in a 2-10 times slowdown compared to the current color reduction algorithm ------------------------------------------------------------------------ Cheers Andrea -- Andrea Aime OpenGeo - http://opengeo.org Expert service straight from the developers. |