10-23-2017, 06:17 PM
I think the key to making the technique work is to have an image that has the full range of luminosities from 0 to 255 so that there's at least a few pixels of each luminosity. A look at the colour "levels" (log view) of the moon image showed that the highest luminosity levels were mostly missing. I scaled levels 0-206 to 0-255 then rescaled the size to 90% which filled in any remaining gaps with Gaussian blur. I then applied the colour gradient that I'd got from the NASA solar flare image.
If the above image is desaturated, maintaining luminosity, then the two halves look almost identical.
I re-extracted the gradient map using my process from the right-hand moon and compared it with my original gradient map. Note that if the full range of luminosities is present in the gradient map, then it should go from full black to full white. They look identical to my eye, although a colourcube-analysis says that the number of colours in the combined image is almost doubled so it's not perfect.
If the above image is desaturated, maintaining luminosity, then the two halves look almost identical.
I re-extracted the gradient map using my process from the right-hand moon and compared it with my original gradient map. Note that if the full range of luminosities is present in the gradient map, then it should go from full black to full white. They look identical to my eye, although a colourcube-analysis says that the number of colours in the combined image is almost doubled so it's not perfect.