Black point compensation vs Black relative exposure

Software ART
1

What is the difference between:
Black point compensation (in Exposure) vs Black relative exposure (in Log Tone Mapping)
in ART?
You can use both to make the dark areas even darker. When do you use one tool and when the other?

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3

And there are at least 5 methods to make the blacks deeper:

  1. Black point compensation (in Exposure)
  2. Tone Equalizer > Black oder Shadows
  3. Tone Curves > increase Contrast
  4. Tone Curves > Tone Curves 2
  5. Log Tone Mapping > Black relative Exposure

Are there better or less good methods here?
When should you use which one?
Or is it, as is almost always the case with ART, that you can take what you want if you are satisfied with the image result?

I have just noticed a huge difference: with “Black relative exposure”, only the dark becomes darker, the brightness and saturation remain completely unchanged. Only “Black relative exposure” does not change the colour!

edit: Even Tone Equalizer does not or hardly changes the colour.

4

I think that’s the right answer. The goal is the resulting image, how you come there is a question of personal preferences. There might be subtle differences between the different tools (or better said technical differences), but I would say: use what works for you.

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5

Yes, of course it is the goal, and ART helps a lot to achieve this quite intuitively.

But hints can be very helpful to understand how an effect really works, especially in comparison to others.

I just discovered today that the colors don’t change with Black relative Exposure. That is a significant difference to most others. But it’s probably best to try everything out for yourself. I don’t always find it easy to try things out systematically, but that’s the best way to learn.

6

The main purpose of black Point compensation in exposure module is to ensure blacks are not being clipped before you do further edits.

Since tone mappers like filmic/agx are designed to be the last tool used in the scene referred pipeline, a main purpose of black relative in these modules is to ensure blacks are not being clipped at output.

Of course, if modules are placed after filmic/agx clipping can still occur, and one can also choose to crush the blacks as an artistic decision.

For modules in the scene referred part of the pipe, between exposure and filmic/agx (like tone eq, color balance rgb, etc), if the blacks are crushed they do not truly clip, since the values can be brought back into range with other modules. This is because they do not work between 0 (black) to 1 (white), but rather infinity to infinity, as best I understand.

EDIT: sorry skimmed through too quick, didn’t see it was about ART. Still, the same idea should hold true.

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