I just recently came across this post which asked exactly the question I was wondering: Blacks and Whites options (I use Lightroom currently, but I’m trying to learn RT, because I’m not going to start paying a monthly subscription just for a RAW processor…)
Thanks to that post, I now know how to adjust the blacks and whites with curves instead! However, now I’m wondering what the “black” slider is there for? Is there any difference between it and adjusting the black point with a curve?
See the section on Rawpedia: Exposure - RawPedia
I find the black slider a better place to start for adjusting the black point, then I adjust the tone curves for more fine grained control on the over all image.
In general I try to get the exposure ‘roughly right’ meaning black & white point where I want them before I get into curves.
It makes adjusting the curves more precise (less ‘dead space’) and a bit simpler because I can just focus on contrast.
I too first get the image into the right ballpark using Exposure and Black, and use the curves after that. There is an open feature request for getting new Auto Levels modes, e.g. one which only fits the histogram using Exposure and Black and nothing more.
So how do you adjust your white point?
White point is an adjustment of Exposure Compensation and Highlight Compression (if necessary).
Usually Exposure to lift things up as needed in an attempt to snug the histogram up to the right side (to taste). For instance, there’s latitude here to push the Exposure up to fill in the top 25% or so:
Often folks will start with adjusting the exposure to bring that histogram up to the right side:
And now you can use the black point to stretch things down dark (again, to taste) if you wanted. I probably wouldn’t here, as the ranges are already pretty close, but some might want to.
I wonder how you folks make use of the shadow compression slider right next to the black slider. For some reason it never seems to make sense to me to set it other than zero. Instead of using a higher black value and then use the compression slider I usually use a lower black value with zero compression, which looks the same to me. Am I missing something?
You could start with the Lab-L curve, do various things with color (which might require adjusting the Lab-L curve), and use a the Black slider toward the end of the work.
“I’m not going to start paying a monthly subscription just for a RAW processor…” The first part of the sentiment, yes, but with RT in the set, how can one refer to “just” a raw processor? 
@RTCharles I guess they mean that a raw processor is a negligeable part of photo processing, and he/she would maybe consider paying for a program that does a considerable amount of cloning and liquefying instead, such as Photoshop.
My own take is that if one does a good job in the raw processor, very little work, aside from extensive artistic “enhancement” is needed - and by that I literally mean cloning and such. But I guess just because I value a good raw processor, not everyone needs to.
Hallo,
how far should you brighten the exposure with Expousure compensation? Up to the desired brightness - or do you have to avoid clipping and make the missing brightness with the curves? Or can exposure compensation be used to create a clear clipping, which you can then take back with highlight compression?
I don’t understand what this has to do with the topic: What is the "black" slider for
Jonas_Wagner told, he: trys to get the exposure ‘roughly right’ meaning black & white point where I want them before I get into curves.
Morgan_Hardwood told: I too first get the image into the right ballpark using Exposure and Black, and use the curves after that.
Therefore the question how far one should increase the brightness with exposure compensation. Until shortly before clipping or without hesitation until a strong clipping, which can be corrected later.
Jonas_Wagner told, he: trys to get the exposure ‘roughly right’ meaning black & white point where I want them before I get into curves.
Morgan_Hardwood told: I too first get the image into the right ballpark using Exposure and Black, and use the curves after that.
Therefore the question how far one should increase the brightness with exposure compensation. Until shortly before clipping or without hesitation until a strong clipping, which can be corrected later.
There is no hard and fast rule and a lot depends on the image and what you want to do with it. However, for a reasonably well-exposed image, I use the Exposure slider to get the mid-tones right and if there is any clipping then I will use the Highlight Compression slider (usually with highlight reconstruction turned on). You may need to move back and forth between the two sliders to get the optimum setting. After that I fine-tune the black and white points if necessary using the curves. Dragging the bottom left hand corner of the curve up or to the right has the same effect as using the black slider. If the mid tones are OK and the whites aren’t completely white (assuming that you want them to be) then it is better to adjust them with the curve (drag the top right hand corner to the left) rather than going back to the Exposure slider (to avoid changing the mid tones).
Again, this is just one approach.
HTH
Hallo Wayne_Sutton,
your answer helps me to understand better. Thank you very much. May I summarize so you can check if I understood everything?
So you can use “Exposure compensation” to increase the exposure until you like the mid-tones, even if the highlights already start clipping. Then you can use “Highlight compression” to get the highlights back.
You control the black and white points only with the curves?
But the slider Black doesn’t (always) do the same as pulling the lower left knot of the curve:
If I drag the lower right knot to the right, the effect is very similar to dragging black to the right. But if I drag this knot upwards, the black is lost very quickly. If I drag the slider Black to the left, the shadows are lightened very well, but there is always a little bit of real black.
And about the white point: I found the slider in RAW: It does exactly the same thing as the slider exposure compensation: both: image and histogram. Do I see this correctly?
With kind regards
micha
personally yes but it is simply a question of preference. Rawpedia has a description of the black slider if you prefer to use that: Exposure - RawPedia
Again, there’s a description of the slider function in Rawpedia. http://rawpedia.rawtherapee.com/Raw_White_Points which states that:
Blockquote
It is unlikely you will ever need to use the Raw White Points tool other than for diagnostic purposes.
This has also been discussed on the forum: If I want my whitest whites to be 255,255,255 - do I adjust the RAW white points?
it is important to me to understand the functions better and better. Then practice a lot. That way I make good progress. Thank you.
micha