[gdal-dev] gdal_calc.py looses the color lookup table

[Even Rouault]

Le mercredi 24 juin 2015 03:49:15, Stephen Woodbridge a écrit :
> Hi All,
> 
> I have a geotiff file like:
> 
> [] ~/work/oceandata/test$ gdalinfo A2015173174000.L0_LAC.L2_OC.tif -noct
> Driver: GTiff/GeoTIFF
> Files: A2015173174000.L0_LAC.L2_OC.tif
>         A2015173174000.L0_LAC.L2_OC.tif.aux.xml
> Size is 2433, 1727
> Coordinate System is:
> GEOGCS["WGS 84",
>      DATUM["WGS_1984",
>          SPHEROID["WGS 84",6378137,298.257223563,
>              AUTHORITY["EPSG","7030"]],
>          AUTHORITY["EPSG","6326"]],
>      PRIMEM["Greenwich",0],
>      UNIT["degree",0.0174532925199433],
>      AUTHORITY["EPSG","4326"]]
> Origin = (-84.000000000000000,45.000000000000000)
> Pixel Size = (0.012741471640766,-0.012738853693008)
> Metadata:
>    AREA_OR_POINT=Area
> Image Structure Metadata:
>    INTERLEAVE=BAND
> Corner Coordinates:
> Upper Left  ( -84.0000000,  45.0000000) ( 84d 0' 0.00"W, 45d 0' 0.00"N)
> Lower Left  ( -84.0000000,  22.9999997) ( 84d 0' 0.00"W, 23d 0' 0.00"N)
> Upper Right ( -52.9999995,  45.0000000) ( 53d 0' 0.00"W, 45d 0' 0.00"N)
> Lower Right ( -52.9999995,  22.9999997) ( 53d 0' 0.00"W, 23d 0' 0.00"N)
> Center      ( -68.4999997,  33.9999998) ( 68d30' 0.00"W, 34d 0' 0.00"N)
> Band 1 Block=2433x3 Type=Byte, ColorInterp=Palette
>    Min=0.000 Max=250.000
>    Minimum=0.000, Maximum=250.000, Mean=0.850, StdDev=9.542
>    Metadata:
>      STATISTICS_MAXIMUM=250
>      STATISTICS_MEAN=0.85033548789076
>      STATISTICS_MINIMUM=0
>      STATISTICS_STDDEV=9.542216344358
>    Color Table (RGB with 256 entries)
> 
> It has multiple entries to the color lookup table that should be treated
> as NODATA for example entries 251-255.
> 
> So I run gdal_calc.py like:
> 
> [] ~/work/oceandata/test$ gdal_calc.py -A
> A2015173174000.L0_LAC.L2_OC.tif --outfile=test.tif --calc="A*(A<251)"
> --NoDataValue=0 --co="TILED=YES"
> 0 .. 10 .. 20 .. 30 .. 40 .. 50 .. 60 .. 70 .. 80 .. 90 .. 100 - Done
> 
> and it create a gray-scale image with no color lut.
> 
> [] ~/work/oceandata/test$ gdalinfo test.tif
> Driver: GTiff/GeoTIFF
> Files: test.tif
> Size is 2433, 1727
> Coordinate System is:
> GEOGCS["WGS 84",
>      DATUM["WGS_1984",
>          SPHEROID["WGS 84",6378137,298.257223563,
>              AUTHORITY["EPSG","7030"]],
>          AUTHORITY["EPSG","6326"]],
>      PRIMEM["Greenwich",0],
>      UNIT["degree",0.0174532925199433],
>      AUTHORITY["EPSG","4326"]]
> Origin = (-84.000000000000000,45.000000000000000)
> Pixel Size = (0.012741471640766,-0.012738853693008)
> Metadata:
>    AREA_OR_POINT=Area
> Image Structure Metadata:
>    INTERLEAVE=BAND
> Corner Coordinates:
> Upper Left  ( -84.0000000,  45.0000000) ( 84d 0' 0.00"W, 45d 0' 0.00"N)
> Lower Left  ( -84.0000000,  22.9999997) ( 84d 0' 0.00"W, 23d 0' 0.00"N)
> Upper Right ( -52.9999995,  45.0000000) ( 53d 0' 0.00"W, 45d 0' 0.00"N)
> Lower Right ( -52.9999995,  22.9999997) ( 53d 0' 0.00"W, 23d 0' 0.00"N)
> Center      ( -68.4999997,  33.9999998) ( 68d30' 0.00"W, 34d 0' 0.00"N)
> Band 1 Block=256x256 Type=Byte, ColorInterp=Gray
>    NoData Value=0
> 
> 
> [] ~/work/oceandata/test$ gdalinfo --version
> GDAL 1.10.1, released 2013/08/26
> 
> So is there away to get gdal_calc.py to copy the LUT to the output file?
> Is there a better way/different way to set these pixels to be NODATA?

Steve,

https://svn.osgeo.org/gdal/trunk/gdal/swig/python/samples/attachpct.py could 
be used as post processing to re-apply the color table.

Even

> 
> Thanks,
>    -Steve
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