Using the Sharpen menu, you can increase the sharpness and enhance the image detail. It includes the effects: Sharpen and Unsharp Mask.
The Sharpen improves the sharpness of the image by increasing the contrast of individual pixels.
Amount (0.0-30.0). The parameter determines the amount of contrast enhancement. When increasing the parameter, light pixels become lighter, while the dark ones become darker.
The Unsharp Mask effect increases the contrast of the edges in the image while leaving other areas untouched. The program compares the resulting image with its blurred copy and if the pixel of the image contrasts with the corresponding pixel of the blurred copy, the contrast is increased; otherwise, the pixel stays unchanged. The program processes all image pixels in this way.
Radius (0.1-250.0). The parameter indicates the number of pixels around the pixel to be corrected (that is the sharpen contour size).
Contrast (1-500). The parameter controls the amount of sharpening.
Threshold (0-255). This parameter determines the size of the areas to be sharpened. At smaller values, the Contrast parameter affects even the individual pixels. At higher values, the parameter affects only the sharpness of distinguished boundaries.
If the Fixed Preview Area check-box is enabled, all changes will be displayed in a small preview area. If the check-box is disabled, the changes will be applied to the area visible in the Image Window.
Click Default to restore the original settings.
Click OK to apply the changes to the image and close the effect dialog box.
Click Cancel to close the dialog box without applying changes.