Dear All, former subject of this thread was "Re: NoDATA value, transparency for paletted IMG file" -
I'm having difficulties displaying 4bit-per-pixel PNG images served via WMS to a GoogleEarth-API-Application (the NoData-Values aren't transparent but "shaded black", whereas this worls well for 8bpp PNG images- so I assume the GE-API can't display transparency for 4bpp PNGs. Is there a way to force mapserver into the creation of 8bpp PNG files, even if the corresponding color table only has 9 entries (I think that's the reason for this)? Thanks for your help and greetings! Chris On Thu, Apr 28, 2011 at 12:42 PM, ChrisFern [via OSGeo.org] <[email protected]> wrote: > Dear Frank, dear all, > > thanks for your reply. > I think I have narrowed down the problem and it isn't really a mapserver > issue - the 8bit paletted img gets rendered to a 4bit-per-pixel png whereas > the correctly transparent RGB img gets rendered to an 8bit-per-pixel png. > Seems that the Google Earth API can't detect/deal with the NoData value in > this 4bpp png and renders this value sort of "shaded black" (which I would > like to get ridd of). GIMP for example can deal with the transparency in > this 4bpp png. > > If I switch to RGBA in the output format, then I have the transparency > however the image is much bigger: > > OUTPUTFORMAT > NAME png > DRIVER "GD/PNG" > MIMETYPE "image/png" > # IMAGEMODE RGBA > IMAGEMODE PC256 > EXTENSION "png" > TRANSPARENT ON > FORMATOPTION "transparent=on" > END > > Is there a way I can force the mapserver to produce 8bpp pngs? > > > THANKS for your help - highly appreciated - and greetings, > > > > Chris > > PS here's the gdalinfo output for the 4bpp png: > Driver: PNG/Portable Network Graphics > Files: lb_usa.png > Size is 1024, 768 > Coordinate System is `' > Corner Coordinates: > Upper Left ( 0.0, 0.0) > Lower Left ( 0.0, 768.0) > Upper Right ( 1024.0, 0.0) > Lower Right ( 1024.0, 768.0) > Center ( 512.0, 384.0) > Band 1 Block=1024x1 Type=Byte, ColorInterp=Palette > NoData Value=0 > Image Structure Metadata: > NBITS=4 > Color Table (RGB with 9 entries) > 0: 1,1,1,0 > 1: 0,0,0,255 > 2: 12,16,120,255 > 3: 31,62,140,255 > 4: 33,110,158,255 > 5: 42,156,154,255 > 6: 61,184,104,255 > 7: 59,214,45,255 > 8: 113,235,47,255 > > ________________________________ > If you reply to this email, your message will be added to the discussion > below: > http://osgeo-org.1803224.n2.nabble.com/NoDATA-value-transparency-for-paletted-IMG-file-tp6305135p6312790.html > To unsubscribe from NoDATA value, transparency for paletted IMG file, click > here. _______________________________________________ mapserver-users mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/mapserver-users
