7. The Menus / 7.7 The Filter Menu
Context Blur is - just as Adaptive Blur - an edge-preserving filter.
For this, the filter searches the edges in the image and blurs along the edges. In areas without edge it behaves like a standard blur.
Context Blur has the following settings:
• Prefilter
Before the edge detection, the image can optionally be blurred. This blurred image is just used for edge-detection and doesn’t influence the end-result by itself.
• Postfilter
The found edges can be blurred, too. Thus individual noise pixels do not affect the result.
• Length
Length is the size of the Context Blur, so it is roughly equivalent to the size of a normal blur.
• Gaussian Weight
By default Context Blur weightens all pixels the same. If Gaussian Weight is activated, nearby pixels are weighted stronger.
Depending on the settings, Context Blur has different fields of use:
• Prefilter small, Postfilter large, Length medium to large
With settings like these Context Blur behaves like an oil color filter.
• Prefilter 0, Postfilter small, Length small to medium, Gaussian Weight
With these settings, Context Blur can be used to reduce image noise or JPEG artifacts.