BlockSigma

BlockSigma[img, {n₁, n₂}] is a nonlinear noise reduction operator.

BlockSigma conditionally replaces each pixel f(r,c) with

of its centered neighborhood of dimensions {n₁, n₂}, where

is the average of all elements of the neighborhood that fall within 2 standard deviations of the neighborhood mean.

This shows the geometry of a 3 × 3 neighborhood centered on f(r,c):

The argument img may be a vector, matrix, or ImageData expression.

See also User's Guide 5.5.

Modified in Version 2.

Example

This loads the package.

In[1]:=

This generates a data array with uniformly distributed additive noise.

In[2]:=

Here is the noisy data.

In[3]:=

Out[3]=

Out[3]=

This demonstrates noise suppression using BlockSigma using 3 × 3 pixel neighborhoods.

In[4]:=

In[5]:=

Out[5]=

Out[5]=

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