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SHARPENING IMAGES WITH SMART SHARPEN
This tutorial was prepared by Roy Killen and is copyright. It is part of the training materials provided for members of the Belmont 16 Ft Photographic Club and is not intended as a complete, stand-alone instruction package.
Comments and suggestions on this tutorial are welcome - they should be emailed to Roy Killen.
Before reading this tutorial you should read the tutorial on IMAGE SHARPENING - BASIC PRINCIPLES.
WHAT SHARPENING FILTERS ARE AVAILABLE IN PHOTOSHOP?
If you have an image open in Photoshop and select Filter>Sharpen you will be presented with five sharpenig options:
Only two of these filters are of use to most photographers: Unsharp Mask and Smart Sharpen.
In this tutorial we consider just the SMART SHARPEN option.
SMART SHARPEN was introduced in Photoshop CS2. It allows you to apply different amounts of sharpening to shadows and highlights and to remove certain types of blur.
THE SMART SHARPEN DIALOGUE
When you select Smart Sharpen the following dialogue opens:
Notice that the BASIC option is selected and the PREVIEW box is ticked.
The Amount and Radius sliders operate in basically the same way as the Amount and Radius sliders in the Unsharp Mask dialogue (refer to this tutorial for further details). However, you probably will not need the Amount as high as you would in USM.
The MORE ACCURATE option improves the sharpening by automatically applying it in stages. It takes longer, but unless you have a very slow computer this will not be a problem.
The REMOVE pop-up menu lets you select whether you want to remove Gaussian Blur, Lens Blur or Motion Blur. If you select Gaussian Blur, the effect will be basically the same as Unsharp Mask. If you select Lens Blur, Photoshop uses a different method to try to detect edges and it often gives a better result with fewer halos. Motion Blur is useful only if you can make an accurate estimate of the direction in which the camera was moving when the image was recorded.
The only immediate change you will see is that the adjustments are now on a tab called "Sharpen". These adjustments work exactly as they did in the Basic mode.
However, there are now two tabs beneath the Sharpen tab, one for Shadow and one for Highlight.
If you select the Shadow tab the dialogue changes to the following:
The FADE slider does exaclty that - it reduces the overall effect of the sharpening that was applied via the Sharpen tab. This is a selective effect that depends on the settngs of the other two sliders.
The TONAL WIDTH slider varies the tonal range over which the fade is applied. For example, if you set the Tonal Width slider to 20% then the fade will be applied to the tones in the lowest 20% of the tonal range (up to 51 on the 0-255 scale). The sharpening effect on the remaining 80% of the tonal range will not be faded.
The RADIUS slider determines what area around each pixel is sampled to determine whether or not the fade is applied.
You will notice that the Tonal Width and Radius sliders in this dialogue behave a lot like the Tonal Width and Radius sliders in the Shadow/Highlight dialogue - refer to this tutorial.
If you select the Highlight tab you get the following dialogue:
The sliders in this dialogue have the same function as those under the Shadow tab, except now you can control the fading of the sharpening in the highlight areas of the image.
OH DEAR AGAIN!
Just as with USM, there are two serious problems with the Smart Sharpen approach to sharpening described above:
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It is destructive and non-reversible - it changes the image pixels forever.
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It applies the same degree of sharpening to all areas of the image that have similar tonal values - whether or not all those areas need sharpening. This problem is not as bad as you might experience by using the Unsharp mask filter, but it is still there.
There are various ways around these problems, some of which are described in the tutorials listed below.
ALTERNATIVE SHARPENING TECHNIQUES
All tutorials and images on this site are copyright.
This page last updated 26th August 2009 (RK)