About the Area Filters

This section describes the filter nodes that operate on a pixel by taking into account the values of surrounding pixels, to perform filtering operations such as edge-detection, blurring and sharpening, noise reduction, etc.

A number of these nodes perform a convolution or other neighborhood operation on each pixel in the image. For the most detailed description of the convolution process, refer to the Convolve node, which is a comprehensive convolution filter featuring a configurable kernel as well as a library of kernel presets.

The Rank node is also a multipurpose filter that can be configured for various tasks and offers a menu of preset operations. Both Convolve and Rank examine pixels surrounding the pixel currently being operated on to obtain a value. However, Convolve averages the pixels in the sample area to obtain a value, whereas Rank sorts the pixels in the sample area and picks one to use for the value based on its ranking in the sort list.

The Blur and Sharpen nodes can be used simply by setting a value for the operation, or advanced filtering options in each node (low pass filter controls in Blur, and high frequency filter controls in Sharpen) can be accessed to precisely control a number of variables.

The Noise node adds video-type noise to an image, and the Grain node includes presets for various film stocks, as well as offering parameters for custom grain pattern matching. The Degrain node offers comprehensive control over the process of removing grain.

The edge operators include the Edge node, for edge detection, and the Erode/Dilate node, for shrinking or expanding edges with subpixel accuracy.

Another special-purpose filter is Unsharp Mask , which sharpens an image using a specific photographic technique that involves boosting the contrast in areas with a lot of detail.

The Filters menu includes the following area filters:

Blur Node
Convolve Node
Degrain Node
Edge Node
Erode/Dilate Node
Grain Node
Noise Node
Rank Node
Sharpen Node
Unsharp Mask Node



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