Sharpen (Unsharp Mask)
![](images/gegl-unsharp-mask.png)
Sharpen image, by adding difference to blurred image, a technique for sharpening originally used in darkrooms.
Radius
Expressed as standard deviation, in pixels
name: std-dev
type: double
default: 3.00
minimum: 0.00
maximum: 1500.00
ui-minimum: 0.00
ui-maximum: 40.00
ui-gamma: 3.00
ui-step-small: 0.01
ui-step-big: 1.00
ui-digits: 3
unit:pixel-distance
Amount
Scaling factor for unsharp-mask, the strength of effect
name: scale
type: double
default: 0.50
minimum: 0.00
maximum: 300.00
ui-minimum: 0.00
ui-maximum: 10.00
ui-gamma: 3.00
ui-step-small: 0.01
ui-step-big: 1.00
ui-digits: 3
Threshold
name: threshold
type: double
default: 0.00
minimum: 0.00
maximum: 1.00
ui-minimum: 0.00
ui-maximum: 1.00
ui-gamma: 1.00
ui-step-small: 0.00
ui-step-big: 0.10
ui-digits: 3
pads: input output
parent-class: GeglOperationMeta
categories: enhance sharpen
![GEGL](../images/GEGL.png)