6.6. Sharpen

Overview

This filter is found in Image>Filters/Enhance/Sharpen

Most of digitized images need correction of sharpness. This is due to digitizing process that must chop a color continuum up in points with slightly different colors: elements thiner than sampling frequency will be averaged into an uniform color. So sharp borders are rendered a little blurred. The same phenomenon appears when printing color dots on paper.

The Sharpen filter accentuates edges but also any noise or blemish and it may create noise in graduated color areas like the sky or a water surface. It competes with the Unsharp Mask filter, which is more sophisticated and renders more natural results.

Options

Preview

Parameter setting results are interactively displayed in preview. Scroll bars allow you to move around the image.

Parameter setting

Increase sharpness: slider and input boxes allow you to set sharpness (1-99) and you can judge result in preview. By increasing sharpness, you may increase image blemishes and also create noise in graduated color areas.