[GRASS-user] Landsat 8 Color Matching

[Michele Toma]

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
michele.toma at airborne.aero<mailto:michele.toma at airborne.aero>
www.airborne.aero

[New Small2]

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