[gdal-dev] palette file format doc ?
Is the palette_file .txt format documented? https://gdal.org/programs/gdalattachpct.html It's mentioned in a few utilities, and created by tests but I couldn't find an existing example or a description (I guessed, incorrectly at first, leaving out the index column). I take it that it is 0-255 range values, but is index 0-based or 1? And, can index be *value* in any contexts? index red green blue If it's documented I'll link it in PRs. I see qml and qlr here: https://docs.qgis.org/3.34/en/docs/user_manual/appendices/qgis_file_formats.html Cheers, Mike -- Michael Sumner Software and Database Engineer Australian Antarctic Division Hobart, Australia e-mail: mdsum...@gmail.com ___ gdal-dev mailing list gdal-dev@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/gdal-dev
Re: [gdal-dev] palette file format doc ?
Michael, Le 20/03/2024 à 21:38, Michael Sumner via gdal-dev a écrit : Is the palette_file .txt format documented? https://gdal.org/programs/gdalattachpct.html It's mentioned in a few utilities, and created by tests but I couldn't find an existing example or a description (I guessed, incorrectly at first, leaving out the index column). I The initial attachpct.py script only worked with a GDAL raster as the source for the palette. The support for text formats, or qml, qlr seems to be a later addition by Idan Miara, and the best doc is probably the code: https://github.com/OSGeo/gdal/blob/master/swig/python/gdal-utils/osgeo_utils/auxiliary/color_palette.py . You may also have a look at autotest/pyscripts/test_gdal_utils.py which has tests for this color palette reading code. Looking a bit at it, I suspect the GDAL text format refered is the one actually used by gdaldem color-relief: https://gdal.org/programs/gdaldem.html#color-relief , which is itself derived from the one used by GRASS r.colors . But the Python code (only Python) and the one used by gdaldem (only C++) are different, so I wouldn't exclude there might be some differences. | take it that it is 0-255 range values, but is index 0-based or 1? 0-based, as (unsigned) raster values are And, can index be *value* in any contexts? If you use a raster with a signed data type, that could be negative values (assuming I understand your question) Even -- http://www.spatialys.com My software is free, but my time generally not. ___ gdal-dev mailing list gdal-dev@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/gdal-dev
Re: [gdal-dev] palette file format doc ?
> > > > > And, can index be *value* in any contexts? > > If you use a raster with a signed data type, that could be negative > values (assuming I understand your question) > > ah I see, arbitrary integer values map to a colour 0:(n-1) colours, match the ordered n values in the raster - that is "value" in the way I was thinking ( I had in mind more general cases like interval ranges, but that's another level up) I might be entirely messing up the concept ... will check my take by experiment. Cheers, Mike -- Michael Sumner Software and Database Engineer Australian Antarctic Division Hobart, Australia e-mail: mdsum...@gmail.com ___ gdal-dev mailing list gdal-dev@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/gdal-dev
Re: [gdal-dev] palette file format doc ?
Le 21/03/2024 à 01:43, Michael Sumner a écrit : > And, can index be *value* in any contexts? If you use a raster with a signed data type, that could be negative values (assuming I understand your question) ah I see, arbitrary integer values map to a colour 0:(n-1) colours, match the ordered n values in the raster - that is "value" in the way I was thinking ( I had in mind more general cases like interval ranges, but that's another level up) I might be entirely messing up the concept ... will check my take by experiment. It was wrong about negative values. As this script ultimately writes a GDALColorTable, you must use >=0 indices. -- http://www.spatialys.com My software is free, but my time generally not. ___ gdal-dev mailing list gdal-dev@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/gdal-dev
