Hi Nikos, everyone, Is the any more information documented about how the i.histo.match tool works? I am unsure if I have entered the correct information to run the tool properly and there is not much information on the documentation page. I ran the tool against all bands in two different images which seemed to work fine (no errors), but when creating an RGB layer of one of the images, it displayed a solid pink image. Displaying an RGB using the bands created before the histogram matching seems to be fine.
-Michele -----Original Message----- From: Nikos Alexandris [mailto:[email protected]] Sent: Tuesday, August 16, 2016 3:22 AM To: Michele Toma Cc: [email protected] Subject: Re: [GRASS-user] Landsat 8 Color Matching Michele Toma: >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? You would want to perform histogram matching after the conversion to radiance/reflectance and before composing an RGB image. >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 Note, this merely retouched the "color-table" and not the data itself. Nikos >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' _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
