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RGB image

RedChannel

Red Channel

GreenChannel

Green channel

BlueChannel

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 masking here.

View more in my DVD Drawing With Light.

Learn more in my digital photography and digital printing workshops.

1_Sharpen_No

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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Multi-pass sharpening combines multiple applications of sharpening on one layer.

Multi-Pass Sharpening

Results will differ if you filter the same image layer twice. Why? First, either the technique or the settings can be varied. Second, having been filtered once, the state of the pixels will have changed before a second pass is applied, generating a different final effect. Consequently, not only the type and amount of filtration matters, but also the order in which the filtration is applied.

One classic multi-pass sharpening technique involves filtering first with an Unsharp Mask setting using a low Radius (under 1.0) and a high Amount (300% or more) and second with an Unsharp Mask setting using a high Radius (approximately1.5) at an Amount of 100%. A variant of this technique adds a third pass of High Pass sharpening. Both methods use the first pass of Unsharp Mask to give the second pass of filtration more to bite into. The key to making any multi-pass sharpening technique successful is to produce a strong yet still convincing effect with as few, if any, unwanted artifacts as possible, either with or without masking.

Some routines will repeat filtration at a lower amount multiple times; for instance, a sharpening setting may be applied ten times at ten percent instead of one time at one hundred percent. The idea behind this approach is that you can achieve a more intense effect (crisper edges) with fewer artifacts (accentuated noise/texture). As it’s inefficient to perform these routines by hand more than one time, this type of approach is best handled by recording an Action that you can play for future uses, which may need to be modified if resolution varies substantially.

Are there benefits to filtering more than twice on the same layer? Maybe. Maybe not. You get diminishing returns with each additional pass of filtration. You may also run the risk of producing more unintended artifacts. Furthermore, as complexity rises your ability to both predict and interact with the final effect diminishes. In general, I recommend you be cautious of highly complex routines and urge you to ask yourself if you derive significant benefit from them.

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Hybrid sharpening combines different sharpening effects using separate layers.

Hybrid Sharpening

Sharpening results will also differ if you apply varied filtration techniques to separate layers. Here, the order of the layers in the layer stack matters.

To combine the effects of the different layers use blend modes: Darken will display the only values on a sharpening layer that are darker than values on layers below it, such as the dark line; Lighten will display the only values on a sharpening layer that are lighter than values on layers below it, such as the halo; Luminosity will display any values that change in brightness, but not hue or saturation, and may override any sharpening effects below them so consider separating one Luminosity layer into two layers, one on Lighten and the other on Darken, as their cumulative effect will enhance rather than override underlying effects.

High Pass sharpening layers (or any technique that reduces an image layer largely to gray values) combine easily with other layers using blend modes (typically Overlay); they do this so well that many times it doesn’t matter whether they are placed above or below other sharpening layers.

To reduce file size, you may decide to merge multiple sharpening layers into a single layer. While this makes a file easier to manage now, it reduces your ability to modify the sharpening effect in the future and to clearly track any effects or artifacts were produced. Weigh the pros and cons of this option carefully.

Selective Sharpening

By keeping sharpening effects on separate layers you not only preserve the future flexibility of the effects you create but you are also able to selectively control the effects and target specific areas of an image more precisely. There are three primary ways of doing this; blend modes; Blend If sliders; and masks. A layer’s blend mode controls the way its values combine with values in layers below it; access a layer’s blend mode at the top of the layer stack. A layer’s Blend If sliders let you quickly remove effects from highlights and/or shadow. Activate a layer’s Blend If sliders by double clicking on it – split the sliders for smoother transitions. A layer mask allows you to target different areas of an image. Add a mask to any layer by clicking the mask icon in the Layers palette and fill (either with selection or brush) areas you want to reduce an effect in with varying shades of gray, darker values reduce effects more.

When you combine different sharpening techniques you’ll find that when it comes to the appearance of detail you’ll have a wider variety of choices to choose from. This can affect more than just the look and feel of your images. You can also use it to guide the eye to specific image areas in different ways, producing a qualitatively different visual journey. Sharpening can make the world looks different. Master sharpening and you may even see the world differently. People who view your images certainly will.

Read more on image sharpening here.

Learn more in my digital photography and digital printing workshops.

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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.

Prevent Clipping

Layers can be used to prevent clipping in deep shadow detail (near-black) and bright highlight detail (near-white). As sharpening is a contrast effect, near-white and near-black values can be driven to pure white and pure black by it. There’s a cure. Double-click the layer to activate Layer Styles. Use the Blend If sliders to reveal the lost highlight and shadow detail in the background layer below the sharpening layer; zoom way into a highlight area, hold the Option/Alt key and drag the right arrow to restore highlights and the left arrow to restore shadows.

Precise Local Adjustment

Layers can be masked for greater control over confined areas in an image. To begin, add a layer mask. Select an area from which you wish to remove a sharpening effect, like a sky or other area of even tone, and fill the area with black. You can use this strategy to remove unwanted texture or noise from selected areas of an image. Gray values can be created on a mask with the Gradient tool or with a Brush tool to gradually reduce a sharpening effect. This often can produce a more strongly felt impression of space within an image. In anticipation of selectively modifying an effect, you may decide to sharpen an image more aggressively.

One approach to gaining additional flexibility with sharpening effects is to set a sharpening layer to 50% Opacity before applying the filter and then later adjust the opacity up or down to get more or less of the effect. This can be useful, but be mindful of its limitations. Reducing or increasing a sharpening layer’s opacity will provide an effect similar to adjusting Amount; more or less contrast is added. But modifying opacity can’t simulate the effects of different Radius settings—thicker or thinner contours.

Combine Multiple Types Of Sharpening

Use more than one duplicate layer and you’ll be able to combine multiple types of sharpening by simply reducing the top layer’s opacity. Unsharp Mask, High Pass, and Clarity all produce different effects that can be combined into still new effects. With these tools, you can craft a unique look and feel for detail in your images.

In addition to the flexibility of changing and/or removing and remaking sharpening effects layers’ features Blend modes, Blend If sliders, Opacity, and Layer Masks offer extraordinary control and precision. When you want to get sharpening effects really right, use layers.

Read more on sharpening here.

Learn more in my digital photography and digital printing workshops.

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Two exposures blended

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Dark exposure

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Light exposure

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The layer stack

Sometimes Two Exposures Are Optimum

There are a variety of ways to extend the dynamic range of a camera. The four classic ways are selective adjustment, double processing a single file, layering two exposures, and merging multiple exposures with HDR software routines.

Layering two exposures produces the best results when a scene has areas of dramatically different brightness separated by clear contours, like but not limited to horizons. For these types of scenes, layering two exposures avoids artifacts that are common in HDR merges, such as saturation distortions, midtone compression, localized vignetting, and detail / noise exaggeration artifacts.

Make Two Exposures Each Optimized For Select Areas

To exceed the dynamic range of a camera’s sensor (or film) you need to make at least two exposures. During exposure(s), rather than rather than striking a compromise between very different brightness values, instead optimize one exposure for each area of brightness, the highlights and the shadows. For each area, expose to the right. Monitor clipping differently. The exposure for the highlights will be clipped in the shadows. The exposure for the shadows will be clipped in the highlights. (If this is not the case, then you may be able to use a simpler technique such as selective adjustement or double processing.)

For this technique you only need two exposures, a very dark and a very light one, but to be on the safe side, make additional exposures in between them. It doesn’t matter which end of the tonal scale (dark or light) you start with. Simply work your way up or down from one to the other. Remember, using a tripod, locking down zoom lenses, and turning off auto focus will all help you register the two exposures more easily.

Process the Two Files Independently

Process the two exposures independently to optimize brightness and contrast separately. In most cases, you’ll want to render color temperature and saturation consistently between the two versions.

Make Each Exposure A Photoshop Layer In A Single File

You can use layers in Photoshop to combine the best information from both light and dark files. Simultaneously highlight the two files you want to use and create layers in Photoshop. Using Lightroom, go to Photo > Edit In > Open as Layers in Photoshop. Using Bridge, go to Tools > Photoshop > Load Files Into Photoshop Layers.

If you want to use Smart Objects, using Lightroom or Camera Raw, open the files separately as Smart Objects into Photoshop. In Lighroom go to Photo > Edit In > Open as Smart Object in Photoshop. In Camera Raw hold the Option/Alt key to Open Object. Then, holding the Shift key to register them, drag one image into the other. It doesn’t matter which layer you place on top. What matters is how you blend the two.

Registering The Two Layers

If you’ve used a tripod during exposure the two files will register instantly. If you’ve hand-held during exposure, they may not. If the layers don’t register you can highlight both layers and choose Edit > Auto-Align Layers. Alternately, use the Move tool and arrows to align the layers manually. Change the blend mode of the top layer to Difference and you’ll see lines around contours, which will disappear when the two layers are perfectly aligned.

Adjust The Mask

Double click on the layer mask and you’ll be able to access the Properties panel, which will allow you to refine the mask. The Feather slider will allow you to soften the edge, but be cautious if you do this as too high a setting will create a soft-edged halo. Click the Refine : Select and Mask and you’ll reveal more options, including the Shift Edge slide, which will allow you to reposition the mask’s contour.

In some cases, light spill or a soft haze of light may extend over the horizon. This may require selective adjustment. Adjust your mask accordingly.

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The layer mask
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The Properties panel for the layer mask

Adjust The Mix

Once the best blend is achieved, you can further enhance it with adjustment layers. Curves and Hue/Saturation are the two most useful types of adjustments.

To affect both layers withone adjustment, simply highlight the top layer and create an adjustment layer. To affect the bottom layer only, first highlight it and second create and adjustment layer, above it and below the top layer. To affect the top layer only, first highlight it and when you create the adjustment layer check the box for Use Previous Layer to Create Clipping Mask. (If you’re using the adjustment layer icon at the bottom of the Layers panel, to access this dialog box, hold the Option/Alt key before creating the adjustment layer.) You can clip or unclip an adjustment layer to a layer at any time by holding down the Option/Alt key and clicking on the line between them in the Layers panel.

Stay Flexible

Use a flexible workflow. Keep your layer stack in tact during editing and when you save your file (as a TIFF or PSD) to preserve your ability to make future improvements. Don’t flatten.

Be As Dramatic As You Want To Be

Using this technique difficult shooting conditions will become much easier for you. Many more image making opportunities will become available to you. It’s well worth investing the time to master these techniques as the versatility they will afford you will be both rewarding and profitable.

The images you create with this technique can be quite dramatic. They can exceed the dynamic range of cameras and sometimes even the human eye. You’ll be challenged to see in new ways. It’s your choice to render realistic or hyper-realistic results. Whatever you choose, your images will provide you and your viewers with a new window on the world.

Read more on HDR techniques here.

Learn more in my digital printing and digital photography workshops.

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

View more Quick Tips here.

Learn more in my digital photography and digital printing workshops.

Julieanne Kost shares the top 10 enhancements in the Layers Panel in Photoshop CS6.

View more Photoshop videos here.

Learn more in my digital photography and digital printing workshops.


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