[Gdal-dev] gdal_translate and Dynamic Range

Scott D. Elko elko1 at llnl.gov
Wed Mar 7 13:32:46 EST 2007

I’ve several 16-bit NITF images. In using OpenEV 1.2.2, I’m able to utilize 
the “Export” function, select “Advanced Options”, use “Draw ROI Mode”, 
select “Window Input File” and “Scale to View Settings” to produce a 
beautiful 8-bit geoTiff chipped out image who’s dynamic range is spot on.

However, no matter what I do, I can’t seem to reproduce the same results 
using gdal_translate. In short, the dynamic range of the gdla_translate 
produced image is not even close (ie., much, much darker) than that of the 
OpenEV image. In addition to specifying –srcwin, the gdal_translate 
parameters, I’m using are:

-scale (w/o any scale factors since it’s suppose to calculate the proper 
min and max for src and dst)
-ot Byte

The only way I’ve been able to get halfway decent results is to specify 
“–scale 0 600” but this seems to be a hack. I’ve even experiment with other 
gdal_tranlsate options to produce exactly the same informational results 
yielded by gdla_info on the OpenEV produced image but have come up empty 

The funny thing is that if I use gdla_translate to produce a geoTiff image 
then apply gdal_translate on that resultant image, as expected, the second 
image is somewhat better but not even close to that of the OpenEV produced.

Can anybody share any ideas in how to get gdla_translate to produce the 
same result as that of OpenEV? Or is it an impossible feat that I’m trying 
to accomplish?


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