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Partition-based
Median type Filters for Suppressing Impulse Noise n Digital Images |
The
ultimate goal of restoration techniques is to improve an image in some predefined
sense. Restoration attempts to reconstruct or recover an image that has been degraded
by using a prior knowledge of the degradation phenomenon. Thus restoration techniques
are oriented towards modeling the degradation and applying the inverse process
order to recover the original image
An adaptive median based filter is proposed
for removing noise from images. Specifically, the observed sample vector at each
pixel location is classified into one of M mutually exclusive partitions, each
of which has a particular filtering operation.The observation signal space is
partitioned based on the differences defined between the current pixel value and
the outputs of CWM center weighted median) filters with variable center weights.
The estimate at each location is formed as a linear combination of the outputs
of those CWM filters and the current pixel value. To control the dynamic range
of filter outputs, a location-invariance constraint is imposed upon each weighting
vector. The weights are optimized using the constrained LMS (least mean square)
algorithm. Recursive implementation of the new filter is then addressed.
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