Effects > Stylize > Smooth
The Smooth filter allows you to smoothen the image. It is similar to Edge Preserving Blur with Radius = 20 and Threshold = 20.
1. Do one of the following:
 Choose Effects > Stylize > Smooth
 Click the Smooth button on the toolbar
2. Use the following options:
 Radius (px)
Determines the number of pixels surrounding the pixel that affect the blurring. The greater the value, the more obvious the blurring.

Min = 5, Max = 200, Default = 20.
This option allows you to control how much the tonal values of neighboring pixels must diverge from the center pixel value before being part of the blur. Pixels with tonal value differences less than the Threshold value are excluded from the blur.

Min = 0, Max = 100, Default = 20.
Related Information
Effects > Blur > Edge Preserving Smooth
Adjust > Add / Remove Noise > Edge Preserving Smooth
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