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SIGMA FILTER - Suppress grain but preserve sharpness

Original
Graininess is a common defect in images taken from film scanner. Smoothing would not help since it deteriorates sharpness of edges in pictures.

Original picture in this example features Gaussian noise which imitates real-life graininess.

 Original graininess
Picture Man 4.2 Sigma Fitter
To remove graininess without affecting sharp edges use Sigma filter of Picture Man TOOLS->ENHANCEMENT->SIGMA FILTER.
The example is result of successive application of filter with parameters (Gap-Size) 12-33x33, 16-33x33, 20-3x3.		 Picture Man 4.1 Sigma Fiter
PSP Edge Preserving Smooth (amount 3)
Compare with tool offered by Paint Shop PRO 7.0 with different values of parameter. Successive application of the tool does not result in better quality. PSP Edge Preserving Smooth (amount 3)
PSP Edge Preserving Smooth (amount 5)
download original uncompressed image (grain_original.tif; 0.5 MB) to test Sigma filter PSP Edge Preserving Smooth (amount 5)
PSP Edge Preserving Smooth (amount 7)
PSP Edge Preserving Smooth (amount 7)

 

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