Histogram Matching question.

Software
1

Hi
I’d like to enquire about Histogram Matching and which software would best suit.
I’d like to deduct one histogram (#values) from a second histogram list of #values.

Any info appreciated, I am learning Rawtherapee and have some experience with Gimp/Gmic.

2

I describe the process of matching histograms using ImageMagick in:
Clut cookbook: Application: Matching histograms and
Process modules: Application: matching histograms

I’m not sure what you mean by “I’d like to deduct one histogram …” Histograms can be subtracted, but I’m not sure why, and that’s not the same as matching them.

3

Alan
I’m getting my terminology from Ai at the moment and it described the process of removing the excess input #values (Freq) from one histogram, to leave only those found in a second histogram (for output).

Ai called it Histogram matching…so I went with it.

I think I have previously dabled with something like this in Gimp, where I got a series of squares in the right-hand pannel, each containing a greyscale tone, derived from an image. I expected that those tones were what made up the histogram colour values…Not quantity.

I’d like to take the tones contained in a second set of #values, which is the maximum i can print, Get rid of all the values (within the first histogram) that are greater than or less than my output capability and Re-order the image using the output range of greyscale.

All work is in greyscale!

Hope thats understandable, I have the concept, but not the terminology or workflow required as yet…and the tools required may be readily available but unrecognised.

Thanks.

4

RawTherapee and its fork ART both have nice JPG matching defaults, which may give you a good starting point to play around and experiment with the light and colour.

1 Like
5

Thanks Alan
I’ll have a look into Art.

6

Alan
Thank you very much.
I cant say for sure because Ai might not be totally correct, but I asked about jpeg matching in RT/Art and it mentioned Tone curves. I then asked abot saving a tone curve and applying it to other images and Ai replied in the affirmative.

I’ll delve a bit deeper tomorrow!

7

Alan
I’ll be attempting a custom tone curve/LUT based on a material test sample of the lasers optimal output range.

I’m off to have a look at Art.

Thanks!