After digging around and comparing other images, I realised that the .IMG
lacks color interpretation since the ColorInterp parameter in gdalinfo
output is undefined
for the 3 bands.
When I attempt to gdal_translate to Gtiff with -expand rgb option, the
error output was: band 1 has no color table.
Any hint on how to properly define color interpretation for a .IMG ? I have
qgis, grass and gdal in an ubuntu setup.
Thanks,
Allan.
On Mon, Jul 14, 2014 at 10:02 AM, Allan Oware wrote:
>
> Hi all,
> Dark tiles are generated when I run gdal2tiles.py on a .IMG file(a scanned
> and georeferenced topographical map).
> A sample png of the tiles generated is found here
> <https://sites.google.com/site/lumtegis/files/519.png>. Even when i
> translate to tiff, the output is still the same. Why does
> gdal2tiles.py give this result ?
> The gdalinfo output is as below:
>
> Driver: HFA/Erdas Imagine Images (.img)
> Files: ALOI.IMG
>ALOI.IMG.aux.xml
> Size is 3830, 2552
> Coordinate System is:
> GEOGCS["GCS_WGS_1984",
> DATUM["WGS_1984",
> SPHEROID["WGS_1984",6378137.0,298.257223563]],
> PRIMEM["Greenwich",0.0],
> UNIT["Degree",0.017453292519943295]]
> Origin = (32.999437318839924,3.000470692247897)
> Pixel Size = (0.000392066994127,-0.000392066994127)
> Metadata:
> DataType=Generic
> Corner Coordinates:
> Upper Left ( 32.9994373, 3.0004707) ( 32d59'57.97"E, 3d 0'1.69"N)
> Lower Left ( 32.9994373, 1.157) ( 32d59'57.97"E, 1d59'59.70"N)
> Upper Right ( 34.5010539, 3.0004707) ( 34d30'3.79"E, 3d 0'1.69"N)
> Lower Right ( 34.5010539, 1.157) ( 34d30'3.79"E, 1d59'59.70"N)
> Center ( 33.7502456, 2.5001932) ( 33d45'0.88"E, 2d30'0.70"N)
> Band 1 Block=64x64 Type=UInt16, ColorInterp=Undefined
> Description = Layer_1
> Min=0.000 Max=255.000
> Minimum=0.000, Maximum=255.000, Mean=225.572, StdDev=31.338
> NoData Value=256
> Overviews: 1915x1276, 958x638, 479x319, 240x160
> Metadata:
> STATISTICS_COVARIANCES=982.046346716112,845.521289084631,710.510646703791
> STATISTICS_MINIMUM=0
> STATISTICS_MAXIMUM=255
> STATISTICS_MEAN=225.57242379015
> STATISTICS_MEDIAN=0
> STATISTICS_MODE=0
> STATISTICS_STDDEV=31.337618714831
> STATISTICS_SKIPFACTORX=1
> STATISTICS_SKIPFACTORY=1
> STATISTICS_EXCLUDEDVALUES=
> LAYER_TYPE=athematic
> Image Structure Metadata:
> COMPRESSION=RLE
> Band 2 Block=64x64 Type=UInt16, ColorInterp=Undefined
> Description = Layer_2
> Min=4.000 Max=255.000
> Minimum=4.000, Maximum=255.000, Mean=226.079, StdDev=29.739
> NoData Value=256
> Overviews: 1915x1276, 958x638, 479x319, 240x160
> Metadata:
> STATISTICS_COVARIANCES=845.521289084631,884.412989496947,765.062067015664
> STATISTICS_MINIMUM=4
> STATISTICS_MAXIMUM=255
> STATISTICS_MEAN=226.07921779459
> STATISTICS_MEDIAN=0
> STATISTICS_MODE=0
> STATISTICS_STDDEV=29.739081853631
> STATISTICS_SKIPFACTORX=1
> STATISTICS_SKIPFACTORY=1
> STATISTICS_EXCLUDEDVALUES=
> LAYER_TYPE=athematic
> Image Structure Metadata:
> COMPRESSION=RLE
> Band 3 Block=64x64 Type=UInt16, ColorInterp=Undefined
> Description = Layer_3
> Min=0.000 Max=255.000
> Minimum=0.000, Maximum=255.000, Mean=172.929, StdDev=27.135
> NoData Value=256
> Overviews: 1915x1276, 958x638, 479x319, 240x160
> Metadata:
> STATISTICS_COVARIANCES=710.510646703791,765.062067015664,736.335138826829
> STATISTICS_MINIMUM=0
> STATISTICS_MAXIMUM=255
> STATISTICS_MEAN=172.92884721066
> STATISTICS_MEDIAN=0
> STATISTICS_MODE=0
> STATISTICS_STDDEV=27.135495920046
> STATISTICS_SKIPFACTORX=1
> STATISTICS_SKIPFACTORY=1
> STATISTICS_EXCLUDEDVALUES=
> LAYER_TYPE=athematic
> Image Structure Metadata:
> COMPRESSION=RLE
>
>
> Thanks,
> Allan.
> --
> Allan Oware
> Cell: +254 727 365820
>
--
Allan Oware
Cell: +254 727 365820
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