6

For any given image, adjusting its levels to increase contrast as in images below, a lot of internal details get darkened and are not noticeable, like the texture of the tree on right, etc.

A

B

However level adjusting to increase highlights and brightness those details are visible again as in the original image. Is there a way to prevent this from happening, any specific technique or tool for this purpose?

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    You need to tell us what software you are using for post production in order to have an answer appropriate for what you are using. – Alaska Man Mar 10 at 16:34
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    Most of the time photographers work very hard at getting an exposure that will show some detail in the shadows instead of just all black. Even shadows have varying degrees of shades of light, are you saying you want to Eliminate all shades of light and have completely black – Alaska Man Mar 10 at 16:52
  • I use Photoshop but wouldn't mind switching to any other applications. Also the shadows don't have to be necessarily black, they could be any color. Take a look at this image, the minute details of the hair that are not there in original cannot be made visible with levels adjustment. It would be better if this can be handled purely in post-process without any additional shots. – durko033 Mar 10 at 19:11
  • Not enough for an answer, but sometimes just playing with the gamma value can improve mid-tone contrast and overall image impression, and -- oh horror -- the auto-adjust feature(s) (plural, because they can be customized) in photoshop are really good when in a hurry. – Peter - Reinstate Monica Mar 11 at 9:04
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    Please define what this means in the final sentence of the question. Do you mean "... a lot of internal details get darkened and are not noticeable, like the texture of the tree on right, etc." or "level adjusting to increase highlights and brightness those details are visible again as in the original image?" – Michael C Mar 12 at 0:10
25

A well know technique is called "luminosity masks". You create a selection mask where the pixels selection level is:

  • 100% or near 100% in the luminosity range that you want to change,
  • 0% or very low in the luminosity range you don't want to change,
  • intermediate for pixels between these two ranges

This done by:

  • making a grayscale copy of your image
  • Applying Curves to isolate the range of interest by making it white and making the unchanged range black (the borders of the range shouldn't be too abrupt)
  • Using the result image as a selection mask

For instance you can make a selection focused on the mid-tones, so you selection mask looks like this:

enter image description here

Or with your image like this (white indicates lack of selection)

enter image description here

And you can then play with the mid-tone contrast without harming shadows and highlights:

enter image description here

The same technique can be applied to select the darks and then lower them without turning all the shadows into charcoal:

enter image description here

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  • Wish I could give it more than +1. Love this technique. – OnBreak. Mar 11 at 4:00
  • Different masks for different effects, masking is definitely the way to go. – Mast Mar 11 at 14:15
  • I find it easier/better to just use "apply image" in multiply mode for the layer mask. The resulting grayscale mask can be farther tailored quite easily (if necessary) using image>adjustments>. – Steven Kersting Mar 11 at 15:03
  • @StevenKersting I'm explaining the general method, you are on your own to adapt it with your favorite photo editing application. – xenoid Mar 11 at 15:26
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    You're answering a different question: how to preserve detail. The question, as is clear from the question title and the last paragraph, is how to best destroy detail without visually impairing the image. – David Mar 11 at 18:44
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I'll interpret your question in the opposite way everyone else has. You seem to me to be asking how to prevent the details becoming visible again. Once you have darkened your image, increase the black point. This will make the new shadows actually black, and prevent the details from being recovered.

You can do this in levels in most editors, or with curves: enter image description here

The details that were preserved in the lower part of the curve will now be black and not recoverable: enter image description here

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    Yes this is exactly what I wanted to achieve but, this process also diminishes the overall quality of the image. Maybe with this and @xenoid's approach can create a better effect. Thanks for your response! – durko033 Mar 11 at 15:05
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    @durko033 To clarify: you would like to destroy (i.e. make not recoverable) shadow detail but not diminish the quality? I'm not sure what you are asking, in that case, since the two aims seem to be diametrically opposed. The method I outline (if the curve above the black point is kept straight and at 45 degrees) will not change any other pixel's value. – David Mar 11 at 15:07
  • For this particular image the dark point you set seems to have a drastic effect on the image quality, although no other color range is affected by this, the image feels bad. Maybe clipping a relatively smaller portion of the dark tones might prevent this, nonetheless my question is answered. My bad for the confusion in the last comment. Thanks Again! – durko033 Mar 11 at 15:16
  • @durko033 if the effect is too drastic, try increasing the dark point by a smaller amount. You can also do this independently by channel if you wish to destroy a single channel's details more or less than another. – David Mar 12 at 11:12
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If there were an easy solution to this, Camera manufacturers would have built it in-camera (and cashed out) long ago :)

Here's the problem.

The best modern cameras are sensitive to at most ~15 stops of dynamic range, whereas estimates have put the dynamic range of the human eye at around 20 stops (see this post, for example). In short, your camera can't see as well as you; and when you encounter high-contrast scenes like this, it's up to you to determine how to realize your creative vision while compensating for those limits.

Some approaches you may be interested in:

  • Dodging and burning, i.e., selectively lightening or darkening areas of your exposure. In concept, it's been used since the dawn of photography.
  • Exposure bracketing, which can be used in post-processing to blend two or more exposures together (usually: one or more underexposed, one correctly exposed, and one or more overexposed)
  • Related to the above: many modern software tools will orchestrate this for you, usually referred to as "HDR".
  • EDIT: See also @David Rouse's excellent response for more ways to approach this in Photoshop. Curves, in particular, can be a wonderful step up from levels (the latter has three variable parameters, while you could go crazy with curves).

Of course, there are many more approaches — experiment, and see what works for you!


To put it another way — when you up the contrast, your editor is doing exactly what you tell it to: making the shadows darker, and highlights lighter.

If the difference between your shadows and highlights is too great... you can always flatten out your tone curve, which is what HDR does. Here's the histogram from a RAW file I shot at sunset in Brooklyn showing significant clipping in both the shadows and the highlights:

enter image description here

And here's the histogram after exposure blending my bracketed shots:

enter image description here

Still needs work; but you've got all the dynamic range there to work with. Note that this can make your shot look super unnatural if you're not judicious with it.


Hope this helps!

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  • Why don't they make better cameras, then? – Sean Mar 12 at 0:27
4

If I understand your question correctly, you are looking for more control over the lightness and darkness over specific parts of an image - more than what the Levels tool gives you.

If so, then with Photoshop you have lots of options. I'll cover a few going from "blunt instrument" approach through to "potentially hours of work". Most general purpose image editors offer these tools, but perhaps in different places - maybe with different names.

  • Image > Adjustments > Shadows/Highlights - This tool tries to selectively lift dark areas of the image without touching items that are without detail. Note this doesn't help much when you have an image where the blacks are already featureless. It also has a highlight controls.

  • Contrast isn't just light and dark! With an image with different colors, you can use Vibrance and Hue/Saturation or other tools to enhance the color contrast between different objects (don't go too crazy).

  • History Brush Tool (On Toolbar) - After you have made a change, you can use this brush to take selected parts of the image back to its original state. Takes a little bit of getting used to, but a reasonably quick way to selectively revert parts of an image.

  • Image > Adjustments > Curves - This tool is like levels, but gives you the ability to create your own control points so you can have finer control over the image's contrast curve. Of course, more control means more complexity and time, but if you need it, it can be valuable. I would recommend using this tool as an adjustment layer (Layer > New Adjustment Layer > Curves) so you can keep making changes after saving the file. And just as with Levels, you can adjust each color separately.

  • Adjustment Layer + Mask - After creating an adjustment layer, you can create a mask to limit the effect of the adjustment. The masks are greyscale (although normally displayed as shades of magenta) with the darker the shade the more the mask stops the affect of the adjustment layer. Here you can paint in the areas you don't want to change with your adjustment. Editing a layer mask takes getting used to, but does offer a huge amount of control. You can, of course, have multiple adjustment layers. As your changes are on an adjustment layer, you can always go back and tweak (as long as you have saved the image as a Photoshop document with layers intact).

Note - all of these techniques work best when you start with enough detail in the dark and light areas. If you don't, you can end up with banding or weird blocks of featureless shadow in the midst of a normally toned scene. So starting out with a good image is half the battle. If you find yourself tweaking images a lot, you also may want to consider shooting RAW. The extra bit depth should give you more room for adjustments before you start seeing artifacts.

Final note - these are not the only tools and techniques available! I certainly recommend googling the tool names to check out both Adobe's documentation as well as any tutorials out there. This entry assumes Photoshop CC 2020, some tools may not be available in earlier versions.

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  • Agree re: Curves panel and Shadows/Highlights sliders. Should have mentioned in my response. Gives you much more control over exposure than just e.g., just brightness and contrast, etc. Also: "Contrast isn't just light and dark!" Absolutely — just to add, I've found you can often "coax" light out of shadows (or vice versa) by using HSL tools, or related effects like split toning. – Jesse Stuart Mar 10 at 21:20
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After some clarification on existing answers, if the intention is to increase contrast, then leave the small sub-highlights in those areas [sparkles, for want of a better word] less visible, then you could try brushing over with the burn tool

This is very rough & I've only done the tree & bottom right corner.
First, I punched up the contrast [unattractively high].

enter image description here

Then, burn tool at 100%, set to highlights.

Sparkles gone.

enter image description here

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