Ciao Ville, I have recently reviewed work on the rastersymbolizer to enhance contrast stretch capabilities (more should come shortly) and I also tried to hack in again the support for 16 bits in a comprehensive way.
You change is ok but of my memory serves me right is not enough. Couple of questions: - have you run a full build of GT? - have you run a full byld of GS? If I remember correctly, this change would not cover all use cases. At least we would need some code GS wise to decide the bit depth prior to rendering. If all test passes, move ahead with a PR and I will make sure we look into it next with Daniele or Andrea. Simone. Il 14/Ott/2015 12:56, "Ville Karppinen" <[email protected]> ha scritto: > Hi, > > I have a change proposal for you on how GeoTools should handle 16-bit > raster content. > > At the moment, geotools rescales 16-bit (ushort) source raster content > to 8-bit. In case of 16-bit source raster data, this may result to > target image that has lost valuable information, which in some use cases > may not be acceptable. Therefore, I propose that geotools would pass > 16-bit source raster content as 16-bit target image unless 8-bit target > image is explicitly requested. The change required to the source code is > really simple and can be viewed here: > https://github.com/TheKarppinen/geotools/tree/fix_16bit_raster > I have included in the commit also necessary changes to test cases. > > I think 16-bit target image would be good feature also from the > GeoServer use case points of view. At the moment, GeoServer queries may > define image format in URL. 8-bit images can be explicitly queried, for > example geotiff8, tiff8, or png8 (FORMAT=image/geotiff8 vs > FORMAT=image/geotiff). But, if FORMAT=image/geotiff is used with raster > style, the target image bit-accuracy should correspond the source data, > instead of always being 8-bit. > > Also, GeoServer and GeoTools have provided 16-bit target content when > 16-bit raster data was queried in previous versions. This behavior has > changed at some point after GeoServer 2.5 that included GeoTools version > 11.0. So, in that sense the change to provide 16-bit target images would > actually provide same behavior that has already been there before. > > I was thinking to make a pull request for this change. But, wanted to > ask about additional comments here first. So, do you think that I may > make the pull request and this change will be included to GeoTools > master branch at some point? > > The change is quite small and I am not sure if contribution license is > required for this. Anyway, I am working for Finnish Meteorological > Institute and our team has already signed the license. Personally for me > this pull request would be the first one. So, I am newbie with the process. > > > Here are still some example results when 16-bit raster content has been > queried from GeoServer and target image content is checked by using > identify-program: > > GeoServer query for 16-bit source content by using format=image/geotiff > current GeoTools implementation gives: > TIFF 485x768 485x768+0+0 8-bit Grayscale DirectClass 373KB > vs. fixed implementation gives: > TIFF 485x768 485x768+0+0 16-bit Grayscale DirectClass 746KB > > GeoServer query for 16-bit source content by using format=image/tiff > current GeoTools implementation gives: > TIFF 485x768 485x768+0+0 8-bit Grayscale DirectClass 373KB > vs. fixed implementation gives: > TIFF 485x768 485x768+0+0 16-bit Grayscale DirectClass 746KB > > GeoServer query for 16-bit source content by using format=image/png > current GeoTools implementation gives: > PNG 485x768 485x768+0+0 8-bit PseudoClass 256c 9.67KB > vs. fixed implementation gives: > PNG 485x768 485x768+0+0 16-bit PseudoClass 65536c 66.4KB > > > Best regards, > > -- > Ville Karppinen > [email protected] > > > > ------------------------------------------------------------------------------ > _______________________________________________ > GeoTools-Devel mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/geotools-devel >
------------------------------------------------------------------------------
_______________________________________________ GeoTools-Devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/geotools-devel
