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Taking baby steps in photo editing, I'm trying out RawTherapee and darktable. They seem to use wildly varying scales for various variables, and even in some variables:

IMG: Darktable

The Black option, for example, has values ranging in the thousands in RawTherapee compared to ≤ 1 in darktable, and Lightness doesn't seem to have any direct parallel in darktable (Brightness seems to have a slightly different effect). I'm trying to compare them to get an idea of which would be more comfortable to use, but such differences have left me confused.

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Well, for the example screenshots that you posted, the RawTherapee "exposure" controls consist of a number of things which darktable dedicates several distinct modules to.

  • The "exposure" slider in darktable would be equivalent to the "exposure compensation" slider in RawTherapee, both giving values in EV. I'm guessing the "black" controls are equivalent as well, but use different units (don't know exactly what units in either case) for measuring black point adjustment.

  • The RawTherapee documentation describes the "lightness" control as applying "a hard-coded tone curve to lift or lower the tonalities of the photo, resulting in a more or less light image". Not exactly sure if there's an equivalent in darktable... maybe adjusting only the middle point of the levels or curves module?

  • For highlight and shadow compression, you'll want to see the "shadows and highlights" module in darktable.

  • There's a module for "contrast brightness saturation" in darktable, but it's probably rarely used because of the sheer number of better options for adjusting all of those things. You may want to use it at first to avoid being overwhelmed, and ease into the more sophisticated modules as you find yourself wanting more control of certain things.

The module section of the darktable manual gives an overview of what they're each used for. While both are very capable of producing good results, the workflow with each of these two great software projects is quite different from the other, particularly in terms of applying similar processing to batches of images, and you'll probably find that you prefer one or the other based on that...

  • I probably should have added screenshots of the other modules to indicate that I am aware of them. But, again, slight differences are present. RawTherapee talks of shadow compression, darktable has both shadows and compress in the shadows and highlights module. – muru Dec 15 '15 at 5:51
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    It's hard to generalize (and I don't have a lot of experience with RawTherapee) but in some ways it seems like it tries to combine things into a "magic" slider (more Lightroom-like?) where darktable favors providing direct control over each and every aspect of what's going on... "compression" in this case controlling how far the effect extends into the midrange, with "shadows" and "highlights" each controlling the amplitude of the effect within the respective portions of the range... – junkyardsparkle Dec 15 '15 at 6:21
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    You could take notes during your comparisons and eventually provide the best answer to your question here. ;) – junkyardsparkle Dec 15 '15 at 6:28
  • So that is the actual RawTherapee documentation site? I visited it earlier, and when it redirected to an IP, I got suspicious. – muru Dec 15 '15 at 6:28
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    Sure, I will attempt that. RawTherapee makes it easier, since it shows a Gimp-like list of changes, which darktable doesn't, AFAICT. – muru Dec 15 '15 at 6:30

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