Photoshop’s Contrast Masks Help You Isolate Highlights Or Shadows

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RGB image

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Red Channel

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Green channel

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Blue channel

The relationship between highlights and shadows is a critical aspect of any image. Photographers have been trained to become highly sensitized to these relationships. Today, photographers have more control and greater precision than ever before over these key visual elements, using the digital darkroom. In Photoshop, the type of adjustment chosen will provide very specific control. The specificity of an adjustment can be further refined by using a mask. One type of mask yields extreme precision and is derived directly from the light and dark relationships within an image, a luminance or contrast mask.

A contrast mask will allow you to target a specific range of tones without affecting the others; highlights, shadows, and even midtones. In the analog darkroom it’s quite challenging and time consuming to make contrast masks; in the digital darkroom it’s quite easy to quickly make contrast masks. And, you can refine or modify them infinitely and indefinitely.

Here’s how to do it.

Load a channel as a selection and with that selection still active create a layer mask. The quickest way to do this is to go to the Channels palette and while holding the Command key click on a channel – R, G, B or RGB. This will create a selection based on the luminance (light and dark) values of the channel you choose.

With so many choices before you, which channel should you choose? Choose the channel that is light in the areas you want to adjust and dark in the areas you don’t want affected. When in doubt, load the RGB master channel as this will give you a selection based on luminance. If you choose an individual channel (R, G, or B) related hues will become lighter than others and complementary hues darker than others – i.e. in  the red channel reds will be very light while cyans will be very dark.

The active selection outline will appear complex; a dotted line will appear at all 50% gray values, but the whole image will be affected to varying degrees based on the density of the values used to make the selection. As values grow darker the affect reduces; as values grow lighter the affect increases. Remember this mantra, “Black conceals; white reveals.” You can turn a selection into a mask in one of two ways, make an adjustment layer (Layer: New Adjustment Layer)(the selection automatically becomes an adjustment layer mask) or make a layer mask (Layer: Layer Mask: Reveal Selection).

As a mask is comprised of shades of gray its lightness and contrast can be adjusted. Very often, contrast masks can be improved by having their contrast adjusted. Use Curves for the greatest precision in contrast adjustment. Here are a few strategies for doing this. Increase the contrast of a mask and its lightest areas will allow more of an effect to show through while its darkest areas will allow less of an effect to show through. Darken the mask and it will allow less of a correction through. Lighten the mask and it will allow more of an effect through. In special cases, you may want to raise the black point when applying Curves to a mask; this will allow some adjustment to be applied to the deepest values with increasing intensity in the highlights. Conversely, you could lower the white point to reduce the effect in highlights or you could simply reduce the opacity of the adjustment layer.

Would you like to target the shadows instead of the highlights? Invert the mask (Image > Adjustments > Invert or Command I) to reverse the relationship between highlights and shadows; black becomes white and white becomes black.

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Mask inverted

Contrast masks add the ability to target highlights and shadows to any color adjustment tool that does not already provide this function and to all filters.

Question whether you need a contrast mask when making image adjustments with Curves, which provides the ability to target specific ranges of tone without the use of a mask. If the adjustment you want to make to a specific region of tones in an image is extreme and you want to substantially reduce the affect on adjacent tones, then, and only then consider using a contrast mask in combination with Curves. Guard against introducing posterization when doing this.

Classically, photographers use a contrast mask when darkening very bright highlights or lightening very dark shadows. For these types of corrections, where industrial strength methods are required, consider using the blend modes Multiply (for highlights) or Screen (for shadows) in combination with a contrast mask to reduce the affect on the opposite end of the tonal scale and prevent loss of detail.

Today, photographers have additional opportunities to enhance color images using contrast masks. In addition to affecting the lightness (luminosity) of highlights or shadows, you can affect their hue and/or saturation. Compare these three solutions; an image with lightened highlights; an image with warmed highlights; and an image with saturated highlights. All three versions will appear more luminous or filled with light, but the qualities of light in each one will differ. After you’ve tried this, try making opposite moves in the shadows. Once you’ve done these experiments, you’ll start seeing new potential in every color image.

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Highlight lightened

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Highlight warmed

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Highlight saturated

Never have we had so much control over the quality of light within our images. Imagine the possibilities. Better yet, experience them. A world of possibilities for image enhancement will unfold before you.

Read more about Selections & Masks.
Learn more in my digital photography and digital printing workshops.

The Essential Photoshop Masking Key Commands

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There are at least two good reasons to become more familiar with Photoshop’s key commands related to masking. First, while many of these functions can be accessed through menu items, not all of them can; these features are essentially hidden to users who don’t know the key commands. Second, key commands that make masking and selections easier and faster.

Here’s a list of the most important Photoshop key commands related to masking.

Option click displays a mask in black and white.

Shift click disables a mask.

Option Shift click displays a mask in red at 50% opacity.

Double click on a mask displays options for changing the color and opacity of mask.

Command click loads a mask as a selection.

Shift Command I click loads an inverted selection.

Shift Command click adds to an existing selection. (gradients add at 50% then 10% increments)

Drag and drop to move a mask from one layer to another.

Option drag and drop to copy a mask from one layer to another.

Delete fills a mask with the Background color.

Option Delete fills with the Foreground color.

Control click on a mask to bring up a contextual menu of options …

      Disable Layer Mask

      Delete Layer Mask

      Apply Layer Mask

      Add Layer Mask to Selection

      Subtract Layer Mask From Selection

      Intersect Layer Mask With Selection

      Layer Mask Options …

As masks are often painted, brush key command are useful too.

Numbers change brush opacity. (1=10%, 2=20%, 3=30%, etc)

X to reverses foreground and background colors.

[ makes a brush smaller.

] makes a brush larger.

Shift [ makes a brush softer.

Shift ] makes a brush harder.

 

Read more about Selections & Masks.
Learn more in my digital photography and digital printing workshops.

Enhancing Local Contrast In Black & White Images

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Color to black and white conversions are radical transformations of an image. They establish the tonal foundations of a neutral image, creating tonal relationships by determining which areas of an image become light and which are dark. While this process can generate some localized effects (all blues become darker or lighter), this is quite different than selectively lightening and darkening an image to accentuate existing tonal relationships (only select blue areas become darker or lighter). Selectively enhance a tonal structure after conversion, rather than before. Selective enhancement may yield dramatic results.
Here are two ways.


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Making Saturation Masks

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Wouldn’t it be great if you could selectively adjust colors based on how saturated they are in Photoshop? You can! How? With a free plug-in Adobe provides called Multiplugin; it hasn’t been updated since Photoshop CS5, but it still works with current versions.
Why Would You Want To Do This?
Do you have images where semi-neutrals aren’t saturated enough, but you don’t want other colors to get too saturated? Select the less saturated colors before adjusting them. Do you have images where you’d like to reduce the saturation of very saturated colors without affecting other levels of saturation? Select the more saturated colors before adjusting them. You even can select colors with medium saturation, separating them from both the high and low range of saturation. Using this technique, you can produce subtle color effects that aren’t possible with any other method.
Saturation masks aren’t for saturation adjustments only. This simple selection/mask can be used with any color adjustment tool in Photoshop, greatly expanding your ability to adjust color. Imagine adjusting the lightness and/or hue of high, medium or low ranges of saturation independently of one another.
Read more here.
Download Adobe’s free Multiplugin here. Mac or PC.
Learn more in my digital photography and digital printing workshops.

Photoshop Masking Key Commands

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The following key commands do not require clicking on the mask.

X                                               reverses Foreground and Background colors
Numbers                               number keys change the Opacity of a brush
[ and ]                                     makes a brush smaller and  larger
Shift [ and Shift ]               makes a brush softer and  harder
Opt Delete                             fills a mask with the Foreground color
Command I                           inverts a mask

The following key commands require clicking on the mask.

Control Click                        displays mask options
Opt Click                                 displays a mask in black and white
Shift Opt Click                      displays a mask as a red overlay

Command Click                   loads the mask as a selection
Shift Command Click        adds the mask to a selection
Option Command Click    subtracts the mask from a selection
Shift Option Command     loads the intersection of two masks
Shift Command I                  inverses a selection

Drag & drop                           to move a mask from one layer to another
Option drag & drop            to copy a mask from one layer to another

Read more about Selections & Masks.
Learn more in my digital photography and digital printing workshops.

Video Quick Tip – 2 Masks For 1 Layer In Photoshop

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In this Photoshop Quick Tip I show how and why to make two masks for one layer.

Read more about Selections & Masks.
Learn more in my digital photography and digital printing workshops.