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SHARPENING IMAGES WITH A SMART FILTER
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 tutorials on IMAGE SHARPENING - BASIC PRINCIPLES and SHARPENING IMAGES WITH UNSHARP MASK.
WHAT IS A SMART FILTER?
The concept of "smart objects" was introduced in Photoshop CS2. When a layer is converted to a smart object you are able to edit that layer externally to Photoshop and then return it to Photoshop in its changed form. You can also scale, rotate, skew or warp smart objects losslessly - but that's a story for another tutorial!
In Photoshop CS3 you can apply filters to smart objects - these are called "smart filters". You can start this process in two ways: (1) by converting a layer (or group of layers) to a Smart Object - just right-click on the layer in the layers palette and select Convert to Smart Object; or (2) by selecting a layer and choosing Convert for Smart Filters from the Layers menu.
The reason that Smart Filters are called "smart" is that they are applied non-destructively (they do not actually alter any pixels in the image). This means that they can be modified after they have been applied and their effects can be masked to limit them to particular parts of an image. In many ways, Smart Filters behave like Adjustment Layers.
SHARPENING WITH A SMART FILTER
In Photoshop CS3 you can use "Smart Filters" to apply any of the five sharpening filters - although normally you would only do it with Unsharp Mask or Smart Sharpen (for the same reasons that Unsharp Mask and Smart Sharpen are your best options for normal sharpening). This has the following advantages:
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The sharpening is non-destructive - it is not applied directly to the image (and, therefore, can be changed later).
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The blend mode can be changed easily to vary the effect of the sharpening.
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A mask can be aplied to limit the sharpening to selected parts of the image.
This process is ideal for an image such as the following one, where you might want to limit the sharpening to some parts of the image.
There are five steps in this sharpening process:
STEP 1: Convert the layer to a Smart Object - right-click on the layer and select "Convert to Smart Object" from the fly-out menu.
Note: The layer icon in the Layers palette will change to indicate that you now have a Smart Object.
STEP 2: Select the filter you want to apply from the filter menu - Unsharp Mask will usually be the best one.
Apply the filter adjustments (amount, radius and threshold) in the same way you would do if you were using the Unsharp Mask filter directly on the image. (Refer to this tutorial.) Then cick OK.
STEP 3: Check that the Smart Filter has been added as an extra entry immediately below the Smart Object in the Layers palette.
The name of the filter (Unsharp Mask in this case) appears and there will be a blank layer mask (the white rectangle).
At any time, you can double-click on the name of the filter to open its dialogue and make further adjustments.
STEP 4: To adjust the blend mode and/or opacity of the filter effect, double-click on the small "sliders" symbol at the right of the name of the smart filter.
This will open a dialogue in which you can select a blend mode - in this case Luminosity is selected so that the sharpening is applied to the luminance (details) of the image but not to the colour information. (The reason for doing this is exxplained in the Unsharp Mask tutorial.)
The filter effect can be faded with the Opacity control in the Blending Options dialogue.
STEP 5: Select the mask by clicking on the white rectangle and paint with black (using a soft edged brush) over the areas of the image where you do NOT want the sharpening to be applied.
That's it. If you save the image as a PSD or TIFF file the information in the Smart Object/Smart Filter layer will be saved and you can make changes to it in future if you want to.
You should be able to see that this approach to sharpening overcomes the two major limitations of using Unsharp Mask or Smart Sharpen on a normal layer - the process is now non-destructive and it can be limited to selected parts of the image.
ALTERNATIVE SHARPENING TECHNIQUES
All tutorials and images on this site are copyright.
This page last updated 26th August 2009 (RK)