yes, I checked the histogram and the out image is completely black. cleo
On Wed, Jul 30, 2014 at 1:53 AM, Jukka Rahkonen <[email protected]> wrote: > Cleo Drakos <cleo21drakos <at> gmail.com> writes: > > > > > Thanks for your response.I tried the followings: > > > > > > gcalc = 'C:\\Users\\cleo\\Documents\\gdalpys\\gdal_calc.py' > > ##I produced second file (b)as the copy of first(a) > > > > a = 'D:\\a.tif' > > b = 'D:\\b.tif' > > outfile = 'D:\\result.tif' > > expr = '(A-B)/(A+B)' > > subprocess.call([sys.executable,gcalc,'-A',a,'--A_band','1','-B',b, > '--B_band','0','--outfile',outfile,\ > > > > '--calc',expr,'--type','Float32','--format','ENVI'],shell=True) > > a,b,outfile = None, None,None > > > > > > Unfortunately, resulted file is completely black. > > > > > > I hope someone can help me. > Have you checked from the histogram that the result is totally black? I > could imagine that bands 1 (A) and 2 (B) can have values close to each > other which makes that A-B is close to zero. That divided by A+B makes > the values even closer to zero and if such Float32 type image is opened > in an image viewer without LUT stretch that could well appear as > totally black. Forget all this if you have checked the histograms. > > -Jukka Rahkonen- > > > _______________________________________________ > gdal-dev mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/gdal-dev >
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