Vantage21st
The Unsharp Mask Tool
Overview
After completing all
cropping, color corrections, resolution and size reductions the next and last step is to
sharpen the image ONLY if it needs it! It's easy to get into the habit of over-sharpening
an image. An over-sharpened image will look harsh and not real. Use this tool
conservatively.
Often an image will be out
of focus or "soft" to begin with. The image will not be "sharp."
Alternatively, the image may start out sharp but after putting the image through
cropping, resolution, and size changes even a sharp original tends to get a
little fuzzy. Photoshop has a Filter named the Unsharp Mask Tool.
This is the best tool to use when learning how to sharpen an image.
There are three values you
will adjust in the Unsharp Mask dialog box.
- Amount
- Radius
- Threshold
These are general guidelines
that work for web images. Please experiment with different settings to get a
feel for how to use this great tool..
Procedure
- Open Filter > Sharpen
> Unsharp Mask
- Using the slider set the Amount value to to 1 %.
- Set the Radius
to a value between of .5
- Set the Threshold
to a value of 3.
- Gradually move the Amount slider to the right. This will increase increase
the sharpening effect. Be sure to watch the image at the SAME time you are ingreasing the Amount slider.
You will see a distinct change or sharpening of the image as you increase
the amount.
- Adjust the Amount
to a value between 1 and 200 % depending on the image. Normally a value between
30 and 150 works well.
- When you are satisfied
with the look of the image, click on OK.
Experiment with other settings
- Normally you will use a low Radius value for web images. A good range to work within is .5 to 1.5.
- Threshold helps to soften or temper the harsh sharpening effect. Normally this value will fall between 1 and 5 for web images.
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Revised October 2005
Copyright 1999, 2006 John Sedgwick
All rights reserved