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Photoshop Elements >

Sharpening >

Sharpening Methods Compared

With Step Wedges

High Pass Filter Sharpening

v.

Unsharp Mask Sharpening

We'll use step wedges to compare High Pass Filter Sharpening and Unsharp Mask Sharpening.

Frequency

Photographs contain high and low frequency image information.

The step wedge below has high frequency image information to the left.

To the right, there's low frequency image information.

An example of high frequency information is the eyelashes on a portrait.

In the same portrait, the eyelid above the eyelashes has low frequency information.

You can think of frequency as being like detail.

High Frequency Lots of Detail
Low Frequency Little Detail

Step Wedge without Sharpening

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High Frequency Image Information Low Frequency Image Information
Lots of Detail Little Detail
Such as Eyelashes Such as an Eyelid

Step Wedge with High Pass Filter Sharpening

The step wedge above was sharpened using High Pass Filter Sharpening.

The radius was set to 10 pixels.

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High Frequency Image Information Low Frequency Image Information

Compare the sharpened and unsharpened step wedges.

The High Pass Filter Sharpening acted largely on the high frequency image information, where sharpening is needed more.

Where sharpening is less needed, on the low frequency image information, there's little sharpening.

Next, the USM filter method was used.

Step Wedge with Unsharp Mask Sharpening

Compare the High Pass Filter Sharpening step wedge with the Unsharp Mask Sharpening step wedge.

Amount was set to 200, radius to 10, and threshold to 0.

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High Frequency Image Information Low Frequency Image Information

Unlike the High Pass filter, the USM filter acted on both high and low frequency image information.

Compare

Here are all three step wedges next to each other.

With Unsharp Mask Sharpening

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No Sharpening No Sharpening

With High Pass Filter Sharpening

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Sharpening No Sharpening

No Sharpening

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Sharpening Sharpening