Level 2 Plus

Lesson 16

Sharpening

All images must be sharpened either in the camera or in software. This lesson shows you how to sharpen images using the software.

Introduction

In this lesson, we will discuss sharpening our digital images. We will show you how to use the “Unsharp Mask” - Photoshop’s strangely named sharpening tool. We will discuss the standard sharpening approach, but will also suggest a simplified approach to sharpening.

A filter in digital cameras prevents separation of the red, blue and green colors from individual pixels on the sensor.

As a result, when digital capture occurs - a blur is induced by this filter.

We must compensate for this filter.

Therefore, every digital image should be sharpened.

Sharpening can occur in the camera or later, using software. Software sharpening gives you more control.

[ Edit ]

From the next menu, click:

[Go to Standard Edit]

Here is an image that we wish to sharpen.

It seems like a crazy name, but the function that we use in Elements to sharpen an image is called the “Unsharp Mask”. Don’t ask why.

From the Main menu, click on:

[ Filter ]              

From the next menu, click on:

[ Sharpen ]

From the final menu, click on:

[ Unsharp Mask ]

If you under-sharpen, the image appears blurry.

If you over-sharpen, you will get white halos around straight lines.

This is the main screen of the “Unsharp Mask” function.

There are three sliders:

1.      Amount

2.      Radius

3.      Threshold

Make sure you can see the preview by clicking on:

[ Preview ]

If you under-sharpen, the image appears blurry.

If you over-sharpen, you will get white halos around straight lines.

You do not need to know this or even read these definitions.

They are here for the curious people.

Radius: This is the size of the area to be sharpened – small areas with delicate detail need a small radius.

Threshold: This defines how much difference there must be between adjacent pixels before Elements treats them as an edge and enhances them. A threshold value of – 0 – tells Elements to sharpen everything. By raising the number, you tell Elements not to sharpen low contrast pixels.

Amount: This reflects how much you want to apply the settings above.

It’s a good idea to move to a part of your preview screen that will help you judge the results of your sharpening.

From the “Tool Box”, select:

[ Hand Tool ]

You can now use your mouse to move around the preview pane as desired.

You can zoom in or out on your preview image by using the:

[ - ]   or [ + ]

If you under-sharpen, the image appears blurry.

If you over-sharpen, you will get white halos around straight lines.

This is the standard approach that is used in most books that deal with sharpening.

We don’t use it.

We find that a simplified approach works better for our needs.

We recommend that you use the simplified approach.

1.      Set Amount to 500%

2.      Set Radius to 1 pixel

3.      Set Threshold to 0 – the picture is now grainy

4.      Increase Threshold until noise just disappears

5.      Increase Radius until picture loses detail – then back off a bit – now there are white halos around the edges

6.      Reduce Amount until picture looks good – this gets rid of the white edges but keeps the sharpening effect

Here we used the standard approach and came up with the following settings:

Amount = 230%

Radius = 0.5

This is the easiest approach. Here, we consider all images to be general images and we use the same settings for every image.

         Amount      = 85%

         Radius       = 0.5 – 1.0

         Threshold = 0

Here we considered this image to be a general image and did not judge it.

We just applied our settings.

Amount = 85%

Radius = 0.7

Threshold = 0

This is an easy approach but requires some assessment of the image. Here, we evaluate all images in respect to how strong and contrasting the lines are. Settings are made on this basis.

1.    Set Threshold  = 0

2.    Assess for sharp, strong, contrasting lines

3.    Assess for soft, low contrast, non-existing lines

4.    Assess for soft lines and moderate contrast

5.    If for web, use special web settings  

The side of this barn has sharp, strong & contrasting lines.

For this type of picture, use the following settings:

Amount = 65%

Radius = 0.2 - 0.5

For this picture, we used the following settings:

Amount = 65%

Radius = 0.3

This picture has soft, low contrast, non-existing lines.

For this type of picture, use the following settings:

Amount = 150%

Radius = 1.0 – 2.0

For this picture, we used the following settings:

Amount = 150%

Radius = 1.5

This picture of a geyser has  moderate contrast lines.

For this type of picture, use the following settings:

Amount = 85%

Radius = 0.5 – 1.0

For this picture, we used the following settings:

Amount = 85%

Radius = 0.7

For this picture, we used the following settings:

Amount = 300%

Radius = 0.3

Summary

In this lesson, we discussed sharpening digital images. We discussed the “Unsharp Mask”. We discussed the standard sharpening approach, but suggested a simplified approach for sharpening.