3.6. Selective Gaussian Blur

3.6. Selective Gaussian Blur
	3. Blur Filters

3.6.1. Overview

Figure 17.20. The Selective Gaussian Blur filter

Original

Blur applied

Contrary to the other blur plug-ins, the Selective Gaussian Blur plug-in doesn't act on all pixels: blur is applied only if the difference between its value and the value of the surrounding pixels is less than a defined Delta value. So, contrasts are preserved because difference is high on contrast limits. It is used to blur a background so that the foreground subject will stand out better. This add a sense of depth to the image with only a single operation.

3.6.2. Activate the filter

You can find this filter in the image menu under Filters → Blur → Selective Gaussian Blur…

3.6.3. Options

Figure 17.21. “Selective Gaussian” filter parameters settings

Presets, Preview, Split view: These options are common to GEGL-based filters. Please refer to Section 2, “Common Features”.
Aux. input: If there is another image on screen, you can select it as auxiliary input.
Blur radius: Here you can set the blur intensity, in pixels.
Max. delta: Here you can set the maximum difference (0-255) between the pixel value and the surrounding pixel values. Above this Delta, blur will not be applied to that pixel.
Clipping: The result of this filter can be larger than the original image. With the default Adjust option, the layer will be automatically resized as necessary when the filter is applied. With the Clip option the result will be clipped to the layer boundary.