[gdal-dev] More information to understand ColorTables in GeoTiffs

[Robert Nix]

Hi,

I'm trying to add a color table to a 1-band UInt16 GeoTiff with Python as follows:

import numpy as np
import gdal

driver = gdal.GetDriverByName('GTiff')
dst_ds = driver.Create('testcolor.tif', 100, 100, 1, gdal.GDT_UInt16)

band = dst_ds.GetRasterBand(1)
band.SetRasterColorInterpretation(gdal.GCI_PaletteIndex)

c = gdal.ColorTable(gdal.GCI_PaletteIndex)
c.SetColorEntry(1,(255,127,0,63))
band.SetColorTable(c)

a = np.random.randint(1,10,size=(100,100))
band.WriteArray(a)

dst_ds = None

The problem is that when i run gdalinfo on the testcolor.tif, it lists 65535 color table entries:

Driver: GTiff/GeoTIFF
Files: testcolor.tif
       testcolor.tif.aux.xml
Size is 100, 100
Coordinate System is `'
Image Structure Metadata:
  INTERLEAVE=BAND
Corner Coordinates:
Upper Left  (    0.0,    0.0)
Lower Left  (    0.0,  100.0)
Upper Right (  100.0,    0.0)
Lower Right (  100.0,  100.0)
Center      (   50.0,   50.0)
Band 1 Block=100x40 Type=UInt16, ColorInterp=Palette
  Color Table (RGB with 65536 entries)
    0: 1,0,0,255
    1: 1,0,0,255
    2: 0,0,0,255
    3: 0,0,0,255
...
  65533: 0,0,0,255
  65534: 0,0,0,255
  65535: 0,0,0,255

What's going on … besides the fact that maybe i'm not understanding color-tables? If it's clear i don't understand, is there a good resource for understanding color-tables? Or must I go learn the source code (which i really don't have to do)?

Thanks
--nix

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/gdal-dev/attachments/20130308/9c691b40/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: smime.p7s
Type: application/pkcs7-signature
Size: 1437 bytes
Desc: not available
URL: <http://lists.osgeo.org/pipermail/gdal-dev/attachments/20130308/9c691b40/attachment.bin>