Photoshop Tutorials: Sharpen Images With The High Pass Filter
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Written by Steve Patteron, Photoshop Essentials.com
In this Photoshop tutorial on digital photo editing, we're going to learn how to easily sharpen an image using Photoshop's High Pass filter.
While debates continue over which of Photoshop's two main sharpening filters is better, "Unsharp Mask" or the new (as of CS2) "Smart Sharpen", one method of sharpening images remains not only highly effective but also much easier to use than either of those sharpening filters, and that's by using Photoshop's High Pass filter.
The reason the High Pass filter technique works so well at sharpening images is because any areas in the image which are not an edge are left untouched. The only areas that have sharpening applied to them are the edges, which is exactly what you want, and also what all of those confusing options in the "Unsharp Mask" and "Smart Sharpen" filters are trying to help you achieve.
With the High Pass filter, you can often get better results than either of the sharpening filters can give you without fumbling around with confusing options. In this Photoshop tutorial, we'll look at how to use it.
Here's the image I'll be using for this tutorial:
Here's how it will look after sharpening it with the High Pass filter:
Let's get started.
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Step 1: Duplicate The Background Layer
The first thing we need to do is duplicate the Background layer, so I'll do that using the quick keyboard shortcut Ctrl+J (Win) / Command+J (Mac). I can see in my Layers palette now that I have my original Background layer at the bottom, which contains my original pixel information, and the duplicate of it, which Photoshop automatically names "Layer 1", above:
Step 2: Change The Blend Mode Of The Duplicate Layer To "Overlay"
Next, we need to change the blend mode of the duplicate layer from "Normal" to "Overlay". The reason is that the High Pass filter is going to turn all non-edge areas of the image into neutral gray, and the Overlay blend mode leaves all neutral gray areas alone, which means no sharpening will be applied to any of those areas. So to do that, go up to the Blend Mode options in the top left corner of the Layer Styles dialog box, click on the down-pointing arrow to the right of the word "Normal", and select Overlay from the list:
Your image will now appear to have way too much contrast, as we can see here with mine:
Don't worry, it's only temporary. We're changing the blend mode now so that we can see a preview of our sharpening being applied with the High Pass filter, which we'll do next.