Digital Photography: Unsharp Mask Demystified

Whenever you resize or edit a digital image, you should consider sharpening your image as a final step. If you sharpen first, and then edit your image further, you are likely to exaggerate the “artifacts” created as part of the sharepening process. Make sure you save your edited image with a different file name, or in a different folder than the original, in case better sharpening algorthims come along in the next few years - I burn my Original images to CD and also store them locally in an “Original Photos” folder. I place the edited versions in a “Photo Editing” folder.

Unsharp Mask There are many techniques for sharpening a digital image, each with pros and cons. The following steps and ideas for using Unsharp Mask apply to Adobe Photoshop and Adobe Elements.

Radius: In general, if you have a low resolution image (fewer dpis) then you need a lower Radius - try setting it to 0.3; if you are working on a high resolution image, then you need a higher Radius. To avoid creating coloured halos around edges of things in your image, reduce your Radius. If you make the Radius too high, you may lose detail in light areas.

Threshold: For “busy” images, set this value to 0. As soon as you have large areas of a similar colour (e.g. blue sky), you should increase this setting to reduce introduction of noise in otherwise smooth areas.

Amount: This value will typically depend on the two settings discussed above. To reduce the constrast introduced by sharpening, try setting this value to its maximum (500%) and then find the smallest Radius at which sharpening is adequate (e.g. start at 0.1 and increase slowly). Be sure you view your image at 100% its actual size.

TechTags Plugin [ San Antonio Photography | San Antonio Photographers | Senior Portraits | Family Portraits ]

Tags

Uncategorized