High dynamic range and local contrast

Software G'MIC
1

Hi,
I would like to ask you a question regarding several closely related processes.
I work with raw format that I convert to TIFF to process it. In photographs with a high dynamic range, and assuming there has been no loss of information in lights and shadows, it is necessary to increase light in shadows and reduce light in highlights, and then increase local contrast. In GIMP with the G’MIC plug-in I find several processes that I might use.

In relation to the dynamic range of the image I might use:

  1. Colors > Exposure (exposure for me is a combination of aperture, ISO and exposure time, but this process has two sliders for shadow level and ‘exposure’). There is a tutorial to bring up the shadows, but what about the highlights?
  2. Colors > Shadows/highlights
  3. Colors > Brightness/contrast
  4. Colors > Auto > Equalize
    My doubt with these ones is because I think that they are several perspectives of the same thing: the modification of the black point, the white point, and the midtones in the histogram; and I have no information on whether they cut out the information or not. Is there any other tool that will help improve the dynamic range of this
    type of images?

Regarding the dynamic range, and trying to be clearer, I am looking for a tool that allows me to increase the space of the shadows and the highlights, at the expense of a compression of the midtones, so that I can extract detail from the extremes of hystogram (and this is not only to move three points in the hystogram I suppose)

To increase the local contrast I might use:

  1. Filters > G’MIC > Details > Local contrast enhancement
  2. Filters > G’MIC > Details > Tone mapping
    Are they the same? From a technical point of view, could someone tell me what each of these processes does?

My question is related to knowing how all those processes work, if they cut information or not, the mathematics on the pixels, … I can’t find information about each process in the web.

Thanks

2

Let us know which versions you are using. It looks like you are mixing GIMP filters with G’MIC ones. To open the G’MIC plugin, you go to

Filters >
image

3

Yes, my question includes processes from both GIMP and G’MIC (I don’t know if you can also tell me something about the processes belonging to G’MIC). In any case, I would appreciate your help in any way you can. My GIMP version is 2.10.12

4

Relevant links:

Local contrast enhancement

Tone mapping

Similarly, you could examine GIMP code/documentation to glean what its filters do.