Hi everyone,

I have multiple Landsat 8 scenes taken on the same day/same path, but they vary 
in brightness. I believe this to be caused by the time of day that the image 
was taken as the northern image is brighter (taken earlier in the day) and the 
southern image is darker (taken later in the day). This has occurred for 
multiple images. Is there a way to make the colors match between tiles?

I've attempted to use i.histo.match on my composite rgb images which resulted 
in distorted colors. Should this tool only be used on grayscale images? Are 
there other GRASS tools I am not aware of that I should be using? Is the color 
distortion caused by any of the other tools that I am using?

Below are the steps that I've taken to process my images:


1.       Import all Landsat 8 bands to GRASS 7.0.4

2.       Convert DN to reflectance

a.       i.landsat.toar input=LC81100362016082LGN00_B 
output=LC81100362016082LGN00_refl metfile=LC81100362016082LGN00_MTL.txt

3.       Pansharpen using i.fusion.hpf

a.       i.fusion.hpf pan=LC81100362016082LGN00_relf8 
msx=LC81100362016082LGN00_refl4, LC81100362016082LGN00_relf3, 
LC81100362016082LGN00_refl2 suffix=hpf

4.       Histogram equalization

a.       r.colors -e map=LC81100362016082LGN00_refl4.hpf color=grey

5.       Color balance using i.colors.enhance

a.       i.colors.enhance red=LC81100362016082LGN00_refl4.hpf 
green=LC81100362016082LGN00_refl3.hpf blue=LC81100362016082LGN00_refl2.hpf

6.       Set region

a.       g.region raster=LC81100362016082LGN00_refl2.hpf

7.       Create RGB composite

a.       r.composite red=LC81100362016082LGN00_refl4.hpf 
green=LC81100362016082LGN00_refl3.hpf blue=LC81100362016082LGN00_refl2.hpf 
output=LC81100362016082LGN00_refl_rgb

8.       Export image

a.       r.out.gdal input= LC81100362016082LGN00_refl_rgb output= 
LC81100362016082LGN00.tif format='GTiff'

Thank you,

Michele Toma
[email protected]<mailto:[email protected]>
www.airborne.aero

[New Small2]

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