darktable has a color mapping module with histogram mapping and LUT, and also a deflickering option to match exposure from photo to photo (intended to be used for timelapses, but it should do the trick).
@snibgo Thanks a lot for your detailed instructions. I understand the principle of your approach. But it will take a while till I understand exactly what the script is doing.
This tweaks the RGB channels, giving each a multiplier and addition to make the mean and standard deviations match the target. This is simpler than the match-histogram method, and the result is fairly good. When the range of input colours is small, it is more reliable than match-histogram, so might be better for a method that chops one image into tiles, finds the tiles in the other input, matches pairwise, then blends the results.
I do my raw inspection in Mathematica, because so far I have never really bothered to learn Python. If you know Python, you could use rawpy · PyPI which utilizes libraw to import your files and try to find what you’re looking for.
I was curious to analize my RAW histograms more in details: view single sensor bin (R,G1,G2;B)… I know I can find into RT with no demosaicing and the inspector…but
I’m amazed in the FOOS there isn’t a software as Rawdigger
I’ve taken up the endeavor a couple of times, but put it aside as more pressing programming arose (sounds more ‘official’ than it is, really about what I felt like doing day-to-day… ), Really, I put a bit of work into rawproc’s histogram, and it meets my needs rather well…
I have put some time into a command-line program that’ll read a raw file courtesy libraw, then walk the image array, collect and sum the channel data per value, and puke it out as comma-separated text suitable for opening in your favorite spreadsheet program. Libreoffice makes a nice histogram of the data with it’s column chart. Works okay on my test raw, but it’s not easily compiled by non-programmers in its present state.
Really, Rawdigger isn’t such a commercial abomination; it helps fund libraw, the open-source core library that some of us use in our raw processing programs.
PS. Idea … and if RT ( because it’s capable to make RAW histogram but in the 0-255 range for gui and velocity needs) could export a RAW histogram scale 1:1 ??