Lightroom: Levels Adjustment?

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The tone curve is great, but will you support Levels adjustment, like in Photoshop? I prefer to work in Levels mode, it's much easier for me to set the black and white points quickly. And hopefully I can set RGB channels separately too.

Thanks!
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ChristopherV

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Posted 8 years ago

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Rikk Flohr, Champion

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The same thing can be accomplished in Lightroom.

The Equivalents are:

Your White Slider: Exposure
Your Black Slider:Blacks
Brightness: Gamma

Your Option/Alt Key previews clipping while moving the White and Black slider.
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TK

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Is it not the case that the truly equivalent effects are achieved by using the point editing mode of the tone curve?
White Slider: Moving the rightmost point to the left.
Black Slider: Moving the leftmost point to the right.
Grey Slider: Move the middle point.

(With every movement, the Y-coordinate (height) of the points must not change).
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Rob Cole

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TK - I had to move *all* the points to produce an increase in exposure, not just the rightmost point. Am I missing something?
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TK

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Rob, make sure that you have a completely linear tone curve when you start (No "Darks", "Highlights", etc. changes). Otherwise a change to exposure will look different. With a linear curve, changing the white point using "exposure" or by dragging the rightmost point in the tone curve to the left should be almost equivalent. I say almost because there is seems to be some non-linear behaviour in the shadows for "exposure". See also these reverse engineered curves for "exposure" in Lightroom. As you can see, they pretty much correspond to moving the rightmost point in a tone curve.

I don't have PS to verify, but I'm confident that the "white slider" in the "Levels" tool, effectively just moves the rightmost point in the tone curve around. This is supported by this explanation of the differences between "Levels" and "Curves".
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Rob Cole

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Quote: "...make sure that you have a completely linear tone curve when you start..." - Ah - *now* you tell me ;-}

Yeah, I have a hunch Lr design is different than some: Lr seems to recompute data when adjusting blacks and exposure, i.e. its handled more like a contrast adjustment or something, whereas others seem to just record an offset, or something like that. I couldn't back that up, but if there is really non-linear behavior in the shadows, that would support my theory.

But it still begs the question:
1. Does the OP not understand blacks & exposure are effectively same as black-point and white-point in other softwares, or is there some reason why this doesn't work out as well. And even if its the latter, is it just because the OP isn't used to it yet...(?)

PS - Great comparison of exposure vs. brightness - thanks for link.
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graham morgan

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Setting the target levels for output, together with separate rgb channels, are (for me) important missing features; I very much hope the can be added.
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graham morgan

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As a long time user of C1 Pro, I really would like LR 3 to echo the better and more complete implementation of the levels tool, as seen in C1. LR 3 is great and is now my tool of choice, but the levels tool can be improved greatly. Take a look at C1 Pro if you don't already understand my point.
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Rob Cole

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Graham - I've issued a separate FR/Idea for independent channel (levels &) curves. But I think if you want to set tonal levels using a method other than Exposure + Blacks you may need to make a case. I mean one can set the target levels for output now, its just a matter of how - what advantages are there in setting using a levels/curve tool vs. basic adjustments?
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graham morgan

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Hi Rob - thanks for your comment, but something seems to be lost in my description, can you tell me how to set output levels to say 005 and 245, I can't see how it is possibly as things stand. Good news for the separate RGB channels, let's see.
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Rob Cole

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Hi Graham - In Basic Adjustments, Exposure sets white point, & Blacks sets black point. The units for exposure are relative. If you're used to a scale from 0-255, you'll need to get used to the relative exposure setting, but I believe the same effect is obtainable, no? - e.g. just drag the exposure slider keeping eye on photo and/or histogram until its right (or drag the exposure zone directly in histogram). The actual exposure number is useful as a reference but most people set exposure based on desired appearance as opposed to numerically.

PS - I came from the land of levels & curves too, but after getting use to Lightroom's way I no longer feel it is lacking.

So, do you just need to get used to a new way, or is there really call for improvement here?
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graham morgan

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Mmmm I still don't see that it's possible, it's just not the same thing. Easily done in PS (lower set of sliders in the levels tool). There does not seem to be any way to cover this within LR.
Guess we'll just have to make the request, and see where it goes.
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Rob Cole

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I don't think I'll be able to help since I don't understand the problem. But this *is* that request. I doubt any change will come unless the shortcoming that you perceive is made clearer. Or maybe Adobe knows exactly what you are talking about - dunno...
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Rob Cole

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Consider making a separate request for independent RGB levels(&curves?)

UPDATE: A separate/independent FR/Idea has been issued for RGB channel levels/curves.
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Rikk Flohr, Champion

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Keep in mind that Lightroom shows you a much more accurate view of what is really happening.

As you slide sliders the histogram stretches and moves. When tonal values move right or left they do so proportionally based upon the decreasing number of tonal values in each 'stop' of light. You, quite literally, move the value of their pixels-interactively. In conjunction with the [Alt/OPT] hinting keys, you have much more accurate feedback.

In Photoshop's levels command, you move A White and A Black point while the histogram doesn't move at all. You really don't see what you are getting as it happens. The result is hidden from you. You can guess but you will never get a true visual feel for the non-linear nature of the movements.

I definitely consider LR's sliders to be an evolution of the Levels adjustment and can't every think of a reason to go backwards.
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Rob Cole

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Right. Put another way: some programs show you an "input" curve, *and* an "output" curve. You adjust levels on the input curve but view the effect on the output curve (and/or the photo). Lightroom has no concept of an input curve - the histogram is the output curve. I see no problem with Lightroom's approach - the output curve is the only one that matters to me, although it does take some getting used to when first coming to Lightroom from other software that does it differently (setting levels on input curve).

Correction: I mispoke earlier: the tone curve is an "input" curve, its just not *normally* used to set the white point. See TK's comments below.
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graham morgan

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Take a look at this and then perhaps we will reach an understanding http://photoshopnews.com/2008/01/14/c... My point is that it's still sometimes desirable, for technical and/or creative reasons, to set output levels to some arbitrary value. This is not the same thing as the basic curves and levels that are already offered, and it is most certainly not doable in Lightroom (in my experience). A small thing perhaps, but I still finding myself doing it in PS, when it would be far better and more convenient as part the the LR work flow.
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Rob Cole

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Thanks Graham. I don't have the time to get to the bottom of this right now, but I believe it is doable in Lightroom 3 using the point curve as TK has suggested. In my opinion this method leaves something to be desired, since you need to start with a linear curve (no points) or it won't work right. But, you may want to consider trying this so at least you can make a more informed argument to support your case (yes it works, but..., or no that's not it at all..., or maybe even "that will do just fine, thank you...)
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graham morgan

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Hi Rob

Indeed, I see that with some change in approach, much of what I need is there. The linear curve does give the best potential, but its much harder to achieve a satisfactory look. For none critical visual effects, the point curve pretty much hits the sweet spot. PS would still be needed in more critical situations, when some specific value needs to be set.

Thanks to all
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TK

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Graham (and Christopher), have you had a look at the point editing mode for the tone curve in LR?

I find the pointers to the "Blacks" and "Exposure" silders to be misleading. I don't see a "Levels" tool as changing the exposure. It changes the input/output response for any given exposure, doesn't it? Whenever exposure control isn't entirely linear (and it isn't in LR) this difference can be important.

The very same input/output mapping that a "Levels" tool does, can be achieved within the point editing mode of the tone curve in LR. Moving the end points of the curve inwards corresponds to moving the black and white levels sliders inwards.

Most "Levels" tools only provide control over one mid-tone (gray) value. The tone curve in LR can do that as well, but on top of that you may insert as many gray values as you desire and subsequently control their input/output response.

Changing "output levels" only, i.e., not changing the input/output response characteristics but only the range in the output (e.g., let it range from 20-240, rather than 0-255) is possible by just changing the height of points on the the tone curve (as opposed to their horizontal location).

AFAIC, the point editing mode of the tone curve gives you everything (and more) you could demand from a "Levels" tool. It might be the case that the shape of the tone curve that results from inserting and moving mid-tone points does not correspond to the effect a "Levels" tool has. If that is the case, however, this may should result in a discussion about tone curve shape control, rather than the conclusion that "Levels" need to be added.

I reckon if you wanted to provide further support for this FR, you should argue why a) I'm wrong or b) I'm correct in principle but that "Levels" adjustments are so frequent (and sufficient) that they should be supported by controls that have better usability than the point editing mode of the tone curve.
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Rob Cole

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TK - Well put, as usual. I am interested in your assessment of the non-linear-ness of the exposure adjustment, as this seems to be the linchpin upon which the rest of this FR/Idea rests. In other words, when/why would a person not want to use exposure for adjusting the effective white point but use the point curve or some such tool with a linear response instead? (I mean other than being used to doing things a certain way...)

Hint: for anybody trying to use the point curve to set white/black points - I recommend starting with a linear curve - after black/white points are set, then add desired curvature...