Unsharp mask. Konica Minolta IV

Unsharp mask

The unsharp mask sharpens edges in the image without affecting overall image contrast. This mask can be used with soft or slightly out-of-focus images. The effect of the unsharp mask is very subtle, but makes a significant improvement to the overall appearance of the image.

Click the unsharp-mask button to open the unsharp-mask dialog box.

Drag the sliders or enter values in the text boxes to adjust the parameters of the mask. The full effect of the unsharp mask cannot be evaluated in the prescan image. It can only be judged in the final scan.

The result of the unsharp mask differs with image resolution. Make several scans with slight changes to the output resolution until the intended result is produced. Clicking the reset button restores the default settings.

With mask

Amount: to adjust the contrast of the mask between 0% and 500%. If the value is too high, pixilation will be apparent; the image becomes noticeably rough or grainy. 150% to 200% is recommended for high-quality printed images.

Radius: to increase the edge sharpness of the pixels. The radius can be adjusted between 0.1 and 5. The default setting is 1. Changes to the radius are more apparent on printed images than images displayed on a monitor. A level of 1 to 2 is recommended for high-quality printed images.

Original image

Threshold level: adjusted in integers between 0 and 255. The default setting is 2. If the difference between the surrounding pixels is greater than the threshold level, that pixel is recognized as a sharp subject pixel. When the level is set to 0, the whole image is corrected. The threshold level can separate smooth or even areas from edges and detailed areas to be sharpened.

Shadow protection level: to limit the sharp subject pixels in the shadows. The level can be adjusted in integers between 0 and 255. The default setting is 16. When the luminance level is greater than the shadow protection level, that pixel is recognized as a sharp pixel.

72 Advanced image processing