This operation attempts to reduce the 'noise' in the image. This can be used to eliminate minor dust and scratches from scanned images.
The principal function of the noise peak elimination filter is to smooth the objects within an image without losing edge information and without creating undesired structures. The central idea of the algorithm is to replace a pixel with its next neighbor in value in a circular neighborhood if this pixel has been found to be noise. A pixel is defined as noise if the pixel is a minimum or maximum within the neighborhood.