Whenever I try to pan-sharpen composites of some Landsat images in GRASS using i.pansharpen
, i.fusion.brovey
or the IHS sharpening method, the output will have some or all of the following characteristics:
- the composite color is in a different hue compared to the un-sharpened composite
- the brightness level is messed up
- the entire composite went all-white/all-black (when using images pre-processed to top-of-atmosphere reflectance or surface reflectance corrections in
i.landsat.toar
)
I've also tried all of the following; but the colors/brightness remained the same or turned even worse:
- Applied
i.landsat.rgb
, before-and-after the pan-sharpening process - Played with the
-f
or-p
flag ini.landsat.rgb
- Tried
r.colors
to edit the color table to grey/grey255/grey.eq - Tried
i.pansharpen
using all Brovey/IHS/PCA methods - Played with the
-l
flag ini.pansharpen
to rebalance the blue-channel
The GRASS GIS manual did explained on how to perform pan-sharpening and color-balancing, but I can't figure out how to combine both processes in a concurrent workflow. I suspected that this is due to my poor understanding of color-tables, color-histogram, etc. in GRASS..
So, can someone explain to me - how do you tackle color-balancing problems when dealing with Landsat images after image-processing in GRASS? Can you share with me your favorite workflow/methods?
Many thanks for any feedback!