You could use a Python/PHP mapscript wrapper that tests to see the number of colors in the PNG before returning it to the client. In such a case you could manipulate the PNG using GD/PAL/Cairo/Graphics-Library-of-the-Month.
----- Original Message ---- > From: Frank Warmerdam <[email protected]> > To: paalkr <[email protected]> > Cc: [email protected] > Sent: Mon, November 2, 2009 8:59:13 AM > Subject: Re: [mapserver-users] Quantize and 8bit/1bit PNG problem > > paalkr wrote: > > Hi! > > > > Could I please ask for a comment on this issue from one of the developers? > > Pål, > > One bit PNGs are a perfectly valid response. I would suggest > two approaches. > > 1) File a ticket with Microsoft on Bing Maps, and hopefully they will > roll a fix into their operational build within a couple days. (ha ha) > > 2) Manually produce a nice empty tile that works with Bing Maps some > other way, and write a script to replace the 1bit PNG file (which should > presumably have a fixed size) with the bing-safe ones. > > Perhaps not the sort of answer you were hoping for, but you did > implore us for comment even when none of us thought we had anything > particularly bright to say. > > Best regards, > > > 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? > > > -- > ---------------------------------------+-------------------------------------- > I set the clouds in motion - turn up | Frank Warmerdam, [email protected] > light and sound - activate the windows | http://pobox.com/~warmerdam > and watch the world go round - Rush | Geospatial Programmer for Rent > > _______________________________________________ > mapserver-users mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/mapserver-users _______________________________________________ mapserver-users mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/mapserver-users
