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Before sharpening

2_Double_USM

Unsharp Mask only

3_Hybrid_USMHighPass

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.

BeforeAfter

There are many things you can do in Photoshop to make the most of shadow and highlight detail in images, even if you didn’t bracket exposures for HDR.

Curves

Curves, the most precise tool for modifying brightness and contrast, allows you to target and adjust shadows and highlights independently of one another. You can use it to reduce contrast and render more detail in very bright highlights and/or very dark shadows. The Curves interface has a feature (The icon looks like a finger with up and down arrows.) that allows you to click on any area of an image to place a point and adjust those values. If you’re adjusting highlights and shadows, it’s quite likely that you will also have to adjust values in the other end of the tonal scale and possibly midtones to generate the best results. Keep it simple; it’s surprising what you can do with just two or three points. Keep it smooth; avoid posterization by not flattening areas of a curve. The Blend Mode Luminosity can be used to remove any unintended shifts in saturation; more contrasti increases saturation while less contrast decreases saturation.

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Curves can be used to lighten shadows and/or darken highlights

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Before Curves

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After Curves

Shadows/Highlights

The Shadow / Highlight feature in Photoshop (Image > Adjustments > Shadow Highlight) can be very useful for more challenging images. It cannot be applied as an adjustment layer but it can be applied as a smart filter. To preserve future flexibility, apply Shadows / Highlights applied to the Background Layer converted to a smart object or to a duplicate Background layer if you plan to use Blend If sliders.

At first glance, Shadows/Highlights appears to offer two simple Amount sliders. Check Show More Options and you’ll find more sliders. The Tonal Width slider specifies which values are and are not affected, similar to a luminance mask. The Radius slider applies a sharpening affect, similar to High Pass filtration, to the affected areas only; this is the slider that does what no other tool does. Additionally, you can apply Color and Midtone adjustments – but there are other better ways to do this.

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The Radius slider in Photoshop’s Shadows/Highlights provides affects not found in other tools

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Before Shadows/Highlights

after_AntXL

After Shadows/Highlights

Screen / Multiply

You can make industrial strength adjustments to an image using the Blend Modes Multiply and Screen found in the Layers palette. (Use the pull down menu that defaults to Normal.) Multiply dramatically darkens an image; it’s like registering two transparencies on a light table. Screen dramatically lightens an image; it’s like registering two projected images on a wall. These effects can be very helpful in making very bright highlight and very dark shadow detail more visible. Blend modes can be applied with any layer. They can be combined with Curves adjustments for even stronger effects. Because their effects are so strong you’ll want to modify their intensity using the Opacity slider or restrict their effects using Blend If sliders or a contrast mask.

Read more about Photoshop Blend Modes here.

Blend If Sliders

To restrict an adjustment to either the shadows, midtones, or highlights, you can use the Blend If sliders found in the Layer Style menu. Double click on the layer (Not the icon or the name, but the area to the right of them.) to activate the Layer Style menu. Then use the sliders in This Layer to remove the effect on the background layer. For smoother transitions, feather the effect by holding the Option/Alt key and splitting the sliders apart.


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T Layer Style dialog with Blend If sliders set to target shadows

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The Layer Style dialog with Blend If sliders set to target highlights

Luminance Masks

To more precisely target a specific range of the tonal scale, you can quickly make precise luminance masks in Photoshop. Simply go to the Channels palette and Command/Control click on the RGB channel. This will load a selection of the highlights. If you want to create a selection of the shadows go to the Select menu and choose Inverse. Then simply make an adjustment layer and the selection will automatically become a mask or target a layer and click the mask icon at the bottom of the Layer palette. You can further modify the brightness and contrast of the mask by applying Curves to it (Image > Adjust > Curves).

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Highlight mask shadowmask

Shadow mask

Read more about luminance masks here.

Blending Channels

Do you still want more? If dynamic range issues persist in one channel (or even two), you can use the information in the other channel(s) to improve it. Use Photoshop’s Channel Mixer or use a duplicate layer’s Layer Styles. It’s a complex technique, but it’s there when you really need it.

Read more about blending channels here.

For even more dramatic effects these methods can be used in combination with one another.

To Merge Or Not To Merge

All of this might make you wonder why you’d ever need to bracket exposures for HDR merges. Actually, there are plenty of times – when the dynamic range of a scene far exceeds the dynamic range of a camera’s sensor. You can use all of these techniques in combination with HDR merges to get optimum results. Knowing why and why not to use HDR merges, when and when not to use them, and how far to go or not go with them will help you master them.

Read more on HDR techniques here.

Learn more in my digital printing and digital photography workshops.

Sharpening With Layers

November 22, 2011 | Leave a Comment |

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

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

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.

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 …

Read more on Digital Photo Pro.

Read more on sharpening here.

Learn more in my digital photography and digital printing workshops.


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