Diffuse and sharpen: add local contrast fine

[wilecoyote2015]

Hello all,

Back then with the display-referred workflow, I tended to use the local contrast module quite often when mapping scenes with high dynamic range.
Although the diffuse and sharpen module comes with a preset do increase the local contrast, it often yielded inferior results in my use cases because it emphasizes lower frequencies and also tends to crush large, dark areas to black.

This new preset is the base I currently use for increasing local contrast.
It focuses more on the enhancement of fine to medium structures, and hence resembles (at least in my perception) something like "clarity" more closely than the standard preset.
Due to the accentuation of finer textures, I called this "local contrast fine".
The strength can be adjusted easily by the diffusion strengths of scales 1 and 4 and also via the number of iterations.

Comparison (order: without local contrast, with new preset, with normal local contrast preset).
The difference is probably hard to spot side-by-side. Notice the emphasis of the texture in the bottom left area.

local_contrast_fine.zip

[TurboGit]

@wilecoyote2015 : Indeed, nice... I do see the fine details in dark areas whereas the other local contrast presets have a tendency do darken out them too much.

[TurboGit]

@wilecoyote2015 : Please never merge master in a topic branch. Also I see that you've changed the preset values, can you describe why has changed visually? What was the goal of this improvement? TIA.

[wilecoyote2015]

Sorry, thank you for bringing that up.
The motivation for the change of preset values are explained briefly in the commit message.
In further testing, I noticed that the initial commit's values could yield ringing artifacts on high-contrast edges. Furthermore, small dark areas could produce a dark halo. The latest commit compensates for that.
There is no visual difference in the example image.
I plan no further adjustments, so that the current version is considered final.

[TurboGit]

I found this new version very very subtle doing change only on fine details, probably what is wanted here but just wanted to be sure I'm not missing something.

[wilecoyote2015]

I found this new version very very subtle doing change only on fine details, probably what is wanted here but just wanted to be sure I'm not missing something.

That is strange. I have double checked that the parameters of the preset are correct.
In the comparison below (100% crop), the differences are quite evident.
Increasing the strength further by increasing iteration count or diffusion parameters tends to yield an overprocessed, HDR-Like look, so for increasing "clarity", at least for my pictures, this seems to be the sweet spot for me.
In particular, the local contrast: fine preset emphasizes the the texture stronger than the local contrast preset.
(Order: raw, local contrast: fine, local contrast)

Edit: A comparison for a more realistic use-case (enhancing the bark texture), with raw on top:

[TurboGit]

Thanks!

[tpinfold]

Great preset. I just quickly checked it in the weekly windows build. I wonder if the name clarity would be more appropriate to let users know what it does best?