8

I believe that the "highlights", "shadows" and "clarity" faders in Lightroom are an interface to an algorithm called local Laplacian filters. (See also a short video on the topic.)

Those controls in Lightroom are great, but looking at the research papers linked above, Lightroom doesn't give the user complete control over the process. There are a lot more than three parameters that could be changed. If the user had complete control over the contrast curve that's used to control the algorithm, it would be possible to control the level of bright details separately from dark details, for example, or to decrease fine details while increasing larger-scale contrast, or any number of other subtle variations that aren't possible in Lightroom.

Because of this, I'm wondering if there is software that offers a similar edge-aware processing technique, but with a more advanced level of control.

The only ones I'm aware of are Adobe Camera Raw (which offers the exact same controls as Lightroom) and Silver Efex Pro 2, which I think uses a different algorithm but with an effect somewhat similar to the clarity control. (It does offer a distintion between "structure" and "fine structure", but the level of control is still very limited.) It seems there is also a programming language called Halide that also offers this algorithm, but I was hoping to find it in the form of a photo editing application.

9

This processing is implemented in darktable via the Local contrast module as explained here. The interface probably isn't as sophisticated as you might like, but may be an improvement on software that errs on the side of user-friendliness. To quote the linked mail:

this module enhances local contrast by using ``Unnormalized bilateral filtering'' as described in http://people.csail.mit.edu/hasinoff/pubs/AubryEtAl14-lapfilters.pdf (the rest of the paper is implemented in a branch).

the detail slider is mapped to the amount the difference to the base image will be multiplied by.

the other two are the range sigma (contrast slider, colour distance, L channel only in this implementation) and the spatial sigma (radius, pixel distance).

the backend uses the bilateral grid.

(Note that as of this post darktable only builds on *nix/OS X.)

Update: new blog post discussing darktable's implementation, and there's an official project for a Windows version now, although it's still in early stages.

  • I'm on OS X. I'll give it a try! – Nathaniel Jan 9 '17 at 11:25
  • Looks like there's more in store: redmine.darktable.org/projects/darktable/repository/changes/src/… – junkyardsparkle Jan 9 '17 at 15:24
  • My verdict so far: it does indeed offer a bit more control than Lightroom does, in that you can control the size of the details to enhance, and there are separate faders for "contrast" and "detail", though I'm not sure what those correspond to exactly. It's much easier to make a horrible mess of an image than in Lightroom, but that's what you'd expect from having more control - it's less foolproof and will require more skill to use effectively. (That's OK, it's what I wanted.) – Nathaniel Jan 10 '17 at 0:21
  • I'll probably accept this answer after some time, but I won't do it yet in case other suggestions come in. – Nathaniel Jan 10 '17 at 0:23
  • 1
    Feel free to never mark as accepted... a question like this one could certainly attract answers slowly over the long term... and yes, darktable will happily give you enough rope to hang yourself, and the default RAW rendering is often not what people are expecting, best suited to people who like to get their hands dirty and learn stuff. ;) – junkyardsparkle Jan 10 '17 at 2:20

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