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.

What In The World Is Detail Frequency ?

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High frequency

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Medium Frequency

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Low Frequency

Frequency is a term that’s being used more and more. That’s because new tools offer you more control over frequency than ever before. Noise reduction, sharpening, and HDR all offer unprecedented control over the look and feel of detail in our images. Frequency is used to describe the amount of detail packed into a given area of an image. This is measured by the amount of tonal variation between rows or columns of pixels. Imagine measuring an image with a line that passes across it (horizontally from left to right or vertically from top to bottom). The mean or average tonal value along lines can be charted and then compared to values from other measurement lines, especially those nearest to each other.


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3 Things Creative Sharpening Can Do For Your Images

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Of the three stages in a sound sharpening workflow – capture sharpening, creative sharpening, and output sharpening – creative sharpening is the stage that has the most impact. The goal of creative sharpening is to give an image a specific look and feel. There are at least three things creative sharpening can do for your images.

One, creative sharpening can prioritize; it can direct attention to specific areas of an image.

Two, creative sharpening can enhance; qualitative aspects of images like texture and line, can be amplified to produce stronger responses.

Three, creative sharpening can be used to accentuate different qualities of light; a great deal of detail is carried by the luminosity component of color and changing it changes the overall appearance of light within the image.

Used consistently creative sharpening can produce a distinctive style that is more easily recognizable to viewers. (Remember, sharpening is a way to enhance details and it may also be used with its counterpart blurring to make effects appear even stronger by comparison.)


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Creative Image Sharpening – Double Pass Versus Hybrid

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Before sharpening

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Unsharp Mask only

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Unsharp Mask and High Pass filters combined

Different sharpening techniques make the world look different. A world of difference can be seen between the thin hard line of Unsharp Mask and the broad feathered line of High Pass Sharpening.

Can you choose a combination of both? Yes, you can! You can choose the texture of one, the halo of another, and the line of yet another, applying them either globally or selectively. You can customize the look and feel of detail in any image or image area with astonishing precision and flexibility.


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The Advantages Of Sharpening With Photoshop’s Layers

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Layers have Blend Modes and can be masked

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Double click a layer to activate its Blend If sliders  

There are many reasons to use layers when sharpening your digital images.

How do you do this? Simply duplicate the Background layer and sharpen the new layer.

Eliminate Saturation Shifts
Layers can be used to eliminate saturation shifts. Change the Blend Mode of a sharpening layer from Normal to Luminosity. Color noise will also be reduced this way.


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Capture Sharpening With Lightroom & Adobe Camera Raw 

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Adobe Camera Raw's Detail panel

Optimal image sharpening is best done in three stages – capture (Do it during Raw conversion.), creative (Do it in Photoshop.), and output (Automate it.).

This article covers the first stage of sharpening – capture sharpening.

Capture sharpening benefits all images. Capture sharpening compensates for inherent deficiencies in optical and capture systems. All lenses and sensors have specific characteristics and deficiencies. They do not all have the same characteristics or deficiencies.

To speed your workflow, default settings for the best starting point for capture sharpening can be determined for all images created with the same lens/chip combination and saved for subsequent use. To optimally sharpen an image, you’ll need to modify these settings to factor in additional considerations – variances in noise (ISO, exposure duration, temperature), noise reduction settings, and the frequencies of detail (low/smooth to high/fine texture) in an image.


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Advanced Creative Image Sharpening Techniques – Double Pass & Hybrid

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No sharpening.

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Double pass Unsharp Mask sharpening.

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Hybrid Unsharp Mask and High Pass sharpening.

Different sharpening techniques make the world look different. A world of difference can be seen between the thin hard line of Unsharp Mask and the broad feathered line of High Pass Sharpening.
Can you choose a combination of both? Yes you can! You can choose the texture of one, the halo of another, and the line of yet another, applying them either globally or selectively. You can customize the look and feel of detail in any image or image area with astonishing precision and flexibility.
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2b_Sharpen_DoublePass


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Creative Sharpening With Photoshop’s High Pass Filter

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A low High Pass filter setting.

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A high High Pass filter setting.

There are three methods of sharpening in Photoshop that we should all be aware of – luminance, edge, and High Pass sharpening. In this order, the three methods become progressively more complex and go to greater lengths to reduce the accentuation of noise.

To minimize the accentuation of noise, luminance sharpening requires that the filter Unsharp Mask’s Threshold setting be set precisely. When this is not enough, edge sharpening adds a mask that targets the contours of an image, allowing more aggressive sharpening with fewer side effects. Like, edge sharpening, High Pass sharpening (named after the filter used to produce the effect) targets contours in an image, but it does so without the need for a mask; a mask which is more complex to produce. Unlike edge sharpening, the contour accentuation it produces is soft, feathered, and wide. The effect is substantially different and can be used for many creative effects. High Pass sharpening is very similar to the effects of ACR and Lightroom’s Clarity slider, but it offers more control and more varied effects.


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Creative Sharpening With Photoshop’s Unsharp Mask

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Precise sharpening can improve almost any image. It helps to know when to apply it, what type of sharpening to apply, how to apply it, and where to apply it.

Forget the filters Sharpen, Sharpen More, and Sharpen Edges. They’re just default settings of Unsharp Mask. Even Smart Sharpen offers few advantages over Unsharp Mask; it’s particularly useful for compensating for trace, but not substantial, amounts of motion blur. My advice? Start with the classic and master it.

Why is a filter that makes images appear sharper called Unsharp Mask? In analog chemical photography, unsharp masks are made with out-of-focus negatives that are registered with an original positive image. During exposure, the blurring adds contrast around contours, making images appear sharper. Digital unsharp mask works the same way, it uses blurring algorithms to add contrast to contours, again making images appear sharper.

What are the ideal settings for Photoshop’s Unsharp Mask filter? There are no ideal settings that will accommodate all images – or image-makers. Settings will be influenced by resolution, ISO, subject, and practitioner. As creative sharpening is primarily an aesthetic decision, individuals are likely to prefer different amounts and types of image sharpness. When it comes to the effects Unsharp Mask generates, there is a general range of believability most viewers share, but whether you play it safe or push the envelope is entirely up to you. You can craft your own sharpening style. To do this, you have to know how the tool works and what to look for.

What are the controls Unsharp Mask offers? Unsharp Mask offers only three controls – Amount, Radius, and Threshold.
What do they do? Amount controls contrast; a higher setting will create a brighter halo, darker line, and contrastier texture. Radius controls how thick halos and lines get. Threshold suppresses the effect in adjacent pixels, base on their relative luminosity; with a very low setting only adjacent pixels that are very close in color will be affected; with a very high setting, many more color values will be affected.


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