[gdal-dev] storing height information in a .tif rather the grayscale in the tif relying on another file

anotherObject ytrapaet at hotmail.com
Tue Feb 23 04:36:02 EST 2010


I have successfully been using gdal_translate to convert some tifs. Viewing
my resulting 8 byte tifs through a GIS viewer, the color ramp is perfect.
However I converted these to 8 byte so i could further work with them in
photoshop. 

When I open one of my 8 byte .tifs in photoshop, the DEM looks different
(looks like some type of stretch, cant be sure, but it looks like standard
deviation. 

I gather this means that when gdal is saving the tif, the actual colors it
stores in the tif are not the elevation values themselves, but instead rely
on a histogram calculation (from an outside file) to correct for showing the
actual elevations.I have tried correcting for this in photoshop, but the
histogram tools are not nearly as sophisticated enough for any precise
manipulation. 

I am still a newbie in gdal.  How can i save an 8byte tif so that the actual
.tif grayscale colors are not stretched at all? (does not rely on another
file to correct for this?). Or conversely, how can I convert how a .tif is
stretched? Is this going outside the realm of gdal_translate?

many thanks for any help.
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