Unsharp Mask – the Last Thing to Do to your Digital Image

The main digital packages such as PaintShop Pro and Photoshop have a fantastic little function called an ‘unsharp mask’

Using the unsharp mask makes it possible for your digitally corrected or resized images to maintain a high quality appearance. If you regularly downsize your pictures (for faster loading on web pages for example) then you may notice that the usual Sharpness function creates a more unnatural

look in smaller sizes images. The unsharp mask, however, because of its adjustability, can produce much better results. It can even increase the sharpness of photos taken directly from your digital camera.

From personal experience, I make sure that I make all other adjustments to a picture before resizing. For example contrast adjustment, saturation adjustment and any noise reduction. I then resize in steps (VERY important), not all in one go, as I feel this retains more of the original picture quality. Only at the very end of the process, when I’m ready to print for example, do I adjust sharpness, and ONLY with the unsharp mask tool, not the normal sharpness adjustment.

In PaintshopPro 10, use the unsharp mask as follows:

To apply low- and high-frequency sharpening

1. Choose Adjust > Sharpness > Unsharp > Mask.

The Unsharp Mask dialog box appears.

2. Set a value from 0.01 to 100.00 in the Radius control to specify the distance (radius) within which the command looks for dissimilar pixels to sharpen.

Higher Radius settings tend to be more suited for softer images, or those with a large subject; photos with lots of fine detail usually require lower Radius settings.

3. Type or set a value from 1 to 100 in the Strength control to specify the overall strength of the command.

4. Type or set a values from 1 to 100 in the Clipping control to specify lightness values that adjacent pixels must have before they are sharpened.

5. Click OK.

Some people have reported that using the unsharp mask before each resizing step can give superior results. Its not something that I have noticed in my own work, but feel free to try it out. But whatever you prefer, make sure its the LAST thing you do to your picture before you call it ‘finished’

Paul Wheeler, Digital Photographer Enthusiast Digital Camera and image articles & tips
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