3.4. Despeckle

3.4.1. Overview

It is used to remove small defects due to dust, or scratches, on a scanned image, and also moiré effect on image scanned from a magazine. You ought to select isolated defects before applying this filter, in order to avoid unwanted changes in other areas of your image.

3.4.2. Activating the filter

You can find this filter through FiltersEnhanceDespeckle.

3.4.3. Options

Figure 16.22. Despeckle filter options

Despeckle filter options

Preview

If checked, parameter setting results are interactively displayed in preview.

Median
Adaptive

Adapts radius to image or selection content (using Histogram). If this option is checked, radius slider is not efficient. It renders a result smoother than with radius alone.

Recursive

Repeats filter action which gets stronger.

Radius

Sets size of action window from 1 (3x3 pixels) to 20 (41x41). This window moves over the image, and the color in it is smoothed, so imperfections are removed.

Black level

Removes pixels darker than set value (0-255).

White level

Removes pixels whiter than set value (0-255).