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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 a 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.

Capture sharpening is determined visually. Perform capture sharpening while previewing an image on a monitor at 100% screen magnification, the magnification that most precisely displays high frequency detail such as texture and noise.

Capture sharpening is best done during Raw file conversion. (Do it after scanning for analog originals.) I recommend importing your Raw files into Photoshop as Smart Objects. If you do this, you can quickly access specific sharpening and noise reduction settings simply by double clicking the image layer. At the same time, you’ll also be able to take advantage of any updates in detail rendering (noise reduction and sharpening) with the click of a button. (Do be mindful that any adjustments you make in Adobe Camera Raw will not be recorded in a Lightroom library.)

Capture sharpening is typically done globally and uniformly to all areas of an image, but on the fly masking routines are recommended for reducing and removing sharpening effects, such as halos on contours and noise in low frequency or smooth image areas.

When performing capture sharpening, err on the conservative side and avoid producing unwanted artifacts. Don’t fall prey to the temptation to fix unwanted sharpening artifacts you could produce at this first stage of sharpening in subsequent stages of image editing; you’ll get better results if you don’t produce unwanted sharpening artifacts at all. Additional sharpening enhancements can be performed locally with more precision in Photoshop during creative sharpening.

Set Clarity before sharpening. It produces a different but related contour contrast. If you change Clarity settings substantially, double check your sharpening settings

Perform noise reduction before capture sharpening. You’ll use slightly more aggressive sharpening settings to compensate for the blurring noise reduction introduces. As with capture sharpening, produce as few artifacts as possible during noise reduction. If you need to perform more aggressive or localized noise reduction, do it in Photoshop. (See my noise reduction series on digitalphotopro.com.)

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Lightroom’s Detail panel

The Detail controls in Adobe Camera Raw and Lightroom are identical; only their appearance varies.

There four Sharpening sliders.

1          Amount controls the contrast of the effect produced.

2          Radius controls the width of halos (light) and lines (dark) produced around contours.

3          Detail skews the effect towards a particularly frequency of detail – high, medium, or low.

4          Masking creates on-the-fly edge masks, removing the effect from smoother lower contrast areas. (You can see the mask when you hold down the Option/Alt key and click on or slide the slider.)

Images with high frequency detail benefit from using smaller Radius settings, higher Amount and Detail settings. (And lower Noise Reduction settings.) Images with low frequency detail benefit from using higher Radius settings, lower Amount and Detail settings. (And higher Noise Reduction settings.) Images with a wider variety of frequencies, especially those that containing significant contours, benefit from higher Masking settings.

If you don’t know where to start, start with an Amount of 100, a Radius of 1.0, and Detail of 50. Then adjust with the above recommendations in mind, but above all look critically at the way the effect affects your image.

There will be many times when you will want to readjust Noise Reduction settings after determining Sharpening settings. The two are intimately related.

Finding an optimum balance involves making trade-offs. Again, be conservative and avoid producing artifacts. This is perhaps the hardest part of capture sharpening, as the tools are powerful and the effects can be compelling so the temptation to go too far is great. Resist. Remember, there’s a second stage of sharpening for localized effects – creative sharpening.

Double processing Raw files with Photoshop will allow you to apply different noise reduction and sharpening settings to different areas of an image with great precision. In one version you can aggressively sharpen high frequency detail with little noise reduction, such as textured stone, and in second version you can minimally sharpen low frequency detail with high noise reduction, such as a clear blue sky. When you do this, you can optimize sharpening settings for one frequency of detail and ignore the artifacts produced in another. With detail settings optimized for different frequencies on separate layers in Photoshop, you can mask the suboptimal areas in the overlying layer and reveal the optimal detail in the layer below. (Here’s an easy way to do this. First, import the first version into Photoshop as a Smart Object. Second go to Layer : Smart Objects : New Layer Via Copy. Third, double click the new Smart Object to change the detail settings in the overlying layer. Note, if you simply Duplicate a Smart Object instead the settings will be reset in both layers. The way you make the Smart Object determines whether the duplicates share the same settings or have different settings.)

Read more in my digital image Sharpening resources.

Learn more in my digital photography and digital printing workshops.

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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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Double 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 double 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

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 in my digital image Sharpening resources.

Learn more in my digital photography and digital printing workshops.

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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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Photoshop’s High Pass filter.

Take these steps to apply High Pass sharpening.

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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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When To Sharpen

The vast majority of photographic images benefit from sharpening.

Before you decide how and when to sharpen images, you need to decide why you’re sharpening them.

The goal of sharpening is to enhance detail rendition without producing distracting visual artifacts.

You’ll find many conflicting philosophies and their accompanying strategies for sharpening images. The seemingly conflicting advice can be hard to reconcile.

Should you sharpen once or multiple times? Should you sharpen differently for different subjects? Should you sharpen differently for different sizes? Should you sharpen differently for different presentation material or supplies? Should you view your files at 100% or 50% screen magnification?

Capture source, output device, substrate or presentation device, presentation size, subject, and artistic intention all play a role in sharpening. The characteristics and solutions for many of these factors can be objectively defined for everyone; at least one of these factors, perhaps the most important, your artistic vision, can only be decided individually.

So, if sharpening is a complex subject, how do you simplify your sharpening workflow to one that’s practical without compromising quality?

Bruce Fraser and Jeff Schewe offer the best advice in their definitive volume on sharpening, Real World Image Sharpening, which I highly recommend you read. Instead of sharpening your images for you, they teach you how to sharpen.

Their philosophy of sharpening is the soundest in the industry, which is why it has been adopted by so many in the industry. They recommend that images be sharpened in a progression of three stages; once for capture sharpening, a second time for creative sharpening, and a third and final time for output sharpening. The objectives and methods of each of these stages vary considerably. When mastered, the whole process can be streamlined to achieve sophisticated results with a minimum investment of time.

Here’s a quick synopsis …

Read more on Creative Image Sharpening here.

Learn more in my Digital Printing and Digital Photography Workshops.

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You can easily see the artifacts digital sharpening produces by intentionally overdoing it.

Here are the seven most common digital sharpening artifacts.

1         Noise

2         Exaggerated Texture

3         Visible Light Halos

4         Visible Dark Lines

5         Loss of Highlight Detail

6         Loss of Shadow Detail

7         Increased Saturation

These artifacts can be reduced in one or more ways. Here’s a list of options for each.

1         Noise

Raise Unsharp Mask’s Threshold.

Use High Pass sharpening.

Blur High Pass layers.

Mask select image areas.

2        Exaggerated Texture

Reduce Unsharp Mask’s Amount.

Use High Pass sharpening.

Blur High Pass layers.

Mask select image areas.

3       Visible Light Halos

Reduce Unsharp Mask’s Radius to make halos thinner.

Reduce Unsharp Mask’s Amount to make halos darker.

Set the Blend Mode of the Unsharp Mask filter or layer it is applied to to Darken.

Use High Pass sharpening for softer more feathered contour accentuation.

4        Visible Dark Lines

Reduce Unsharp Mask’s Radius to make halos thinner.

Reduce Unsharp Mask’s Amount to make halos darker.

Set the Blend Mode of the Unsharp Mask filter or layer it is applied to to Lighten.

Use High Pass sharpening for softer more feathered contour accentuation.

5         Loss of Highlight Detail

Use a sharpened layer’s Layer Styles / Blend If sliders to recover it.

Mask the highlights.

6        Loss of Shadow Detail

Use the Blend If sliders in Layer Styles to recover it.

Mask the shadows.

7         Increased Saturation

Change the blend mode of the filter or sharpened layer to Luminosity.

Desaturate High Pass layers.

Read more about sharpening here.

Learn more in my digital photography and digital printing workshops.

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