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Sharpening >

Introduction

This section covers the topics below.

The second section has an example of sharpening.

Why Do Photographs Look Soft?

Here's a square and a circle.

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When you enlarge the square and circle to 1200%, below:

• The square looks sharp.

The square pixels line up precisely with the edge of the square.

• The circle isn't sharp.

The pixels can't rotate to follow the edge of the circle.

They jut out.

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How often do you photograph perfectly vertical-and-horizontal shapes?

Rarely.

The world doesn't look like the image below, all verticals and horizontals, . . .

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. . . including the hair.

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The circle above has a bad case of the jaggies.

The cure is sharpening.

The square-and-a-circle photograph below was sharpened, but not in the black box.

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Sharpened

As you can see, sharpening doesn't get rid of the jaggies.

Sharpening is a visual trick.

The contrast is increased along the edge of the circle.

We see the increase in contrast as an increase in sharpness.

To see the difference more clearly, do the following.

1) Download square_and_circle_student_version.psd.

2) Zoom in on the the black square.

3) Click the eye icon on the Sharpening layer to turn the sharpening on and off.

When Do You Sharpen?

Sharpening is the last step.

You make a layer that contains all of the layers of your photograph.

This layer is called a composite layer.

You sharpen the composite layer.

A Little Art History

Sharpening isn't new.

Pigment artists have used similar techniques over the centuries.

For example, Canaletto better defined the architecture of Venice by using narrow black lines along the edges of buildings in his paintings.*

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In the painting below, you can see how El Greco used "sharpening" by placing black around the hand of Christ.

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Detail

JPEGs & Sharpening

You may not have noticed any softness in your photographs if they're saved using the JPEG file format.

If so, your camera is probably sharpening them automatically.

You can modify this automatic sharpening somewhat to fit the subject matter of your photographs.

For example, if you're photographing a headshot for an actor friend with a poor complexion, you may want to decrease sharpening.

Or, if your photographing the subtle color variations in a stone countertop for a brochure, you may want to increase sharpening.

Check the menu on your camera.

Primary Sharpening Determinant - Detail

The principal determinant of sharpening is the amount of detail in the photograph.

Photographs with lots of detail, such as an ancient Greek krater depicting athletics, often require more sharpening.

Photographs with little detail, such as a foggy moor, often need very little sharpening.

Detail & Frequency

You may encounter the term frequency for detail.

High frequency image information is detail.

Low frequency image information is little detail.

Photographs with

Both Detail & Little Detail

Of course, many photographs contain areas with detail and little detail.

These photographs may require selective sharpening.

With selective sharpening, you can "burn-and-dodge" with sharpening.

You can use more sharpening in parts of a photograph, and less in other areas.

Sharpening Methods

Adjust Sharpness

Beginners may want to start with this method, although the High Pass Filter Sharpening below is easy as well.

Go to Adjust Sharpness.

High Pass Filter Sharpening

High Pass Filter Sharpening has several advantages over other sharpening methods.

Go to High Pass Filter Sharpening.

Unsharp Mask Sharpening

The Unsharp Mask sharpening method is the most popular sharpening method, even though it has some disadvantages compared to High Pass Filter Sharpening.

Go to Unsharp Mask Sharpening.

100% (1:1)

This is because anti-aliasing is performed at other view enlargement settings, making it harder to see the actual effect of the sharpening filter.

Selective Sharpening

You can apply sharpening to parts of a photograph.

For example, you could add sharpness only to the eyes, nose, and mouth, on a headshot.

By doing this selective sharpening, blemishes and wrinkles won't be emphasized by the sharpening.

If you already know how to use the methods below, jump to the selective sharpening tutorials for each method.

Go to Selective High Pass Filter Sharpening.

Go to Selective Unsharp Mask Sharpening.

Sharpening Theory

11 - How Unsharp Mask Sharpening Works

2 - Unsharp Mask Sharpening Math

3 - Colors, Too

More

Experiment with Gray Boxes

Sharpening Methods Compared with Step Wedges

Next

The next section has an example of sharpening.

* Mitchell, W. (1992). The reconfigured eye. Cambridge, MA: MIT Press.