The Denoise filter is a powerful form of noise reduction. At higher settings, it also creates a really pleasing, posterizing effect.
About the Denoise filter
This filter can be applied as a non-destructive, live filter. It can be accessed via the Layer menu, from the New Live Filter Layer category.
Settings
The following settings can be adjusted in the filter dialog:
Luminance Denoise—controls the intensity of noise removal from the luminance channel. Type directly in the text box or drag the slider to set the value.
Color Denoise—controls the intensity of noise removal from the chrominance channel. Type directly in the text box or drag the slider to set the value.
Detail—controls the final quality of the reduction. Higher values will give a better quality finish but the application of the filter will take longer. Type directly in the text box or drag the slider to set the value.
Contribution—determines the opacity of corrected pixels. '100%' makes corrected pixels fully opaque; 50% makes pixels 50% transparent.