[QGIS-trac] Re: [Quantum GIS] #1643: Raster: Problems displaying Int16 grayscale image

[Quantum GIS]

#1643: Raster: Problems displaying Int16 grayscale image
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        Reporter:  timlinux          |         Owner:  ersts        
            Type:  bug               |        Status:  assigned     
        Priority:  minor: annoyance  |     Milestone:  Version 1.0.3
       Component:  Rasters           |       Version:  HEAD         
      Resolution:                    |      Keywords:  raster black 
Platform_version:                    |      Platform:  Debian       
        Must_fix:  No                |   Status_info:  0            
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Changes (by ersts):

  * status:  new => assigned

Comment:

 Can someone post me the output from gdalinfo on an image they are having
 problems with? Also please let me know how the U16Bit image was created.

 I can get a similar type of behaviour when I convert at 32-bit image with
 values from 0.0 to 1.0 and a no data value of -9999.0 with the following
 command

 gdal_translate -ot UInt16 -of GTiff -scale 0 1 B1.asc B1_3.tif

 It is all black image and stretching appears to does little, but if I use

 gdal_translate -ot Byte -of GTiff -scale 0 1 B1.asc B1_3.tif

 It get something that "looks" more correct, but still is not actually. The
 problem is that gdal seems to be changing the no data value to 0 even when
 I explicitly set it to something else and if the image has a bunch of no
 data values, 0 dominates the stretch.

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Ticket URL: <http://trac.osgeo.org/qgis/ticket/1643#comment:6>
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