Using Exposure and Brigthness

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Harry Briels

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After having been using Lightroom from its first edition, I still have difficulties understanding when and how to apply "Exposure" and/or "brightness" in post processing images.
In case an image is underexposed or overexposed what should I do?
Increase/decrease exposure or increase/decrease brightness?
 
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Exposure is applied to the full image equally shadows, midtones and highlights. Brightness will have the most effect on the midtones and shadows but little effect on the highlights.
 
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Hi Muizen!

Denis' assessment of their effect is correct.

My preference is to start with exposure to get in the general area of what I want and then apply brightness if needed. My usual workflow is to start general and work down to the specific. In the end it is a subjective decision and your eye is what matters. Enjoy!
 
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Another way of looking at it, which might help. Try using Exposure to set your white point - the brightest point in the image - to the level you want, and then using Brightness to adjust the overall brightness.
 
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Victoria Bampton said:
Another way of looking at it, which might help. Try using Exposure to set your white point - the brightest point in the image - to the level you want, and then using Brightness to adjust the overall brightness.
Click to expand...

How can I "set the white point"? Is this done in LR by keeping down the alt key and clicking on the exposure and then move exposure until the screen is completely black, or is this done by moving the exposure combined with recovery to the right to a point where clippings of the high lights is just avoided?
Thank you for your help!
 
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Denis de Gannes said:
Exposure is applied to the full image equally shadows, midtones and highlights. Brightness will have the most effect on the midtones and shadows but little effect on the highlights.
Click to expand...

I hate to disagree w/ the experts here, but I don't believe this explanation of the exposure slider is strictly true. In my experiments (and as shown in the user interface), the exposure slider affects the 3/4 tones and the highlights much more than the mid-tones, shadows and 1/4 tones. All of the tonal sliders have some affect on all of the tones, but I find it useful to think of their primary affects as follows:

Recovery: The upper 10% or so (highlights)
Exposure: The 3/4 tones
Brightness: The mid-tones
Shadows: The 1/4 tones
Blacks: The lowest 10% or so

There's significant overlap between the sliders, as none of them have a sharp cutoff, but they each have less affect as you move further from their primary zone. In use, I tend to adjust the tones of the image that need the most adjustment first, using the slider that's closest to those tones, and then tweak the others as needed. So, to get back to the OP's question, if the image seems to need adjusting most in the 3/4 tones, I would start by adjusting the exposure; when the 3/4 tones look right, I would then focus on the mid-tones and adjust the brightness as needed. I would do the reverse if it seemed like the mid-tones were most in need of adjustment. Sometimes it may make more sense to start w/ the shadows, or the highlights. Try working that way for a few images and I think you'll get a better feel for what the sliders are actually doing. My $.02 worth. Cheers,
 
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Bruce, thank you for your explanation and advise.
I still would like to understand in what way I can "set the white point"? Is this done in LR by keeping down the alt key and clicking on the exposure and then move exposure until the screen is completely black, or is this done by moving the exposure combined with recovery to the right to a point where clippings of the high lights is just avoided?
Thank you for your help!
 
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"Setting the white point" simply means that you decide what should be the brightest part in your photo. This is normally done using Exposure. If some parts then tend to be overexposed you can rescue them by using Recovery. It doesn't necessarily mean that something needs to be bright white though. Suppose you have a photo of a black cat in a dark room: no white there, but you can still set the "white point" to determine the brightest parts of this dark photo.

Holding down the Alt-key just lets you see when parts become burned out. This in itself has really nothing to do with the white point.
 
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boneywhitefoot said:
I think you might be getting white balance and white point confused.
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Can you please be so kind as to be more specific.

As I understand the "white balance",which I feel is for me not a problem, it sets the color temperature and tint and has very little to do with the "white point" (?)
So far I believe I have learned from this discussion that in setting the white point I determine how light the highlights can be set (without causing overexposure/clipping) Also that brightness influences the mid tones in the image.

In my view well understanding the exposure and brightness is key in post processing.
Thanks!
 
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Whilst what the sliders do may be constant I find that their actual effect depends on the photo. Depending on the overall exposure I tend to increase brightness and reduce exposure and increase both fill and blacks. If necessary I increase recovery. I did use a preset to reflect these preferences but prefer to start from a fairly neutral setting so I can see the effect each slider has on the photo.

Brightness and fill can also affect the White point ! I can eliminate all highlight clipping with the exposure and / or recovery slider and then clip the highlights by increasing brightness and even fill. Adjusting the colour settings can also effect the White point. Ditto with the black point.
 
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I seems somewhat strange to read the advise to "first set the white point", and then when I ask to explain "how one sets the white point" there is no answer I can understand.
I would appreciate if somebody could explain how "to set the white point".
Thank you!
 
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Sorry Muizen. To set the white point, you can either use the clipping warnings (press J) or hold down the Alt/Opt key while moving the Exposure slider. That will get you to the right ballpark, and then add a bit of intelligence too.

You're wanting to adjust the Exposure slider until the brightest part of the image is white, or at the level that looks best. In most cases you will want bright white, however in the case of a low contrast or dark image, you may want a slightly darker white.

Once you've done that, you can then go ahead and adjust the midtones of the image, and recovery will work well to pull down any leftover highlights that get pushed slightly out of range.
 
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As I wrote in #8, a photo doesn't necessarily have to have a pure white in it. But you can still set the "white point", meaning that you adjust exposure until the brightest part of your photo is as bright as you want it to be.

Most "normal" photos will however probably have a full range of light levels ranging from black to white, and there you can use the Alt key to really see when parts of the photo start clipping.
 
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