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I created some GOES-16 images where the dark/night side of the visible image is transparent (alpha channel). I used satpy's DayNight Compositor to make the night side of the image transparent, while keeping the day time in gray scale. Unfortunately, using this method has converted the original L (gray) image into an RGBA image.

I tried using PIL to convert the image from RGBA mode to LA mode but it removes the georeferenced data in the GeoTiff.

img = Image.open(filename_of_RGBA).convert('LA')
img.save(new_filename)

How can I keep the georeferenced data while converting from RGBA to LA?

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  • Here is some Python code to transfer metadata between geotiffs. gis.stackexchange.com/questions/264644/…
    – GBG
    Commented Feb 10, 2021 at 22:17
  • You can select bands with gdal_translate -b option, the real question is how to undo the pan sharpening, perhaps a GDAL_Calc on the bands to estimate the lightness that was used. Either option will retain your georeference.
    – Michael Stimson
    Commented Feb 11, 2021 at 0:21
  • @GRG for some reason when I tried the approach mentioned in the link, it didn't work for me. I ended up finding a solution link
    – weather_sat
    Commented Feb 14, 2021 at 20:17

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I was able to copy the georeferenced data from the RGBA image to the LA image by using a command line tool I found here from David Strip-2.

Given a GeoTIFF file named original.tif, and a modified file (modified.tif) without the GeoTIFF tags, but still the same size and region:

listgeo -no_norm original.tif > original.geo
geotifcp -g original.geo modified.tif modified_geotiff.tif
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