Journal ArticleDOI
Optical median filtering using threshold decomposition
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TLDR
An incoherent optical correlation system performs the linear filtering, using a magnetooptic spatial light modulator as the input device and a computergenerated hologram in the filter plane.Abstract:
A hybrid optical/electronic system performs median filtering and related ranked-order operations using threshold decomposition to encode the image. Threshold decomposition transforms the nonlinear neighborhood ranking operation into a linear space-invariant filtering step followed by a point-to-point threshold comparison step. Spatial multiplexing allows parallel processing of all the threshold components as well as recombination by a second linear space-invariant filtering step. An incoherent optical correlation system performs the linear filtering, using a magnetooptic spatial light modulator as the input device and a computergenerated hologram in the filter plane. Thresholding is done electronically. By adjusting the value of the threshold, the same architecture is used to perform median, minimum, and maximum filtering of images.read more
Citations
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References
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Journal ArticleDOI
A fast two-dimensional median filtering algorithm
Thomas S. Huang,G. Yang,G. Tang +2 more
TL;DR: A fast algorithm for two-dimensional median filtering based on storing and updating the gray level histogram of the picture elements in the window is presented, which is much faster than conventional sorting methods.
Journal ArticleDOI
A theoretical analysis of the properties of median filters
Neal C. Gallagher,G. Wise +1 more
TL;DR: In this article, the authors derived necessary and sufficient conditions for a signal to be invariant under a specific form of median filtering and proved that the form of successive median filtering of a signal (i.e., the filtered output is itself again filtered) eventually reduces the original signal to an invariant signal called a root signal.
Journal Article
Stack filters
TL;DR: This investigation of the properties of stack filters produces several new, useful, and easily implemented filters, including two which are named asymmetric median filters.
Journal ArticleDOI
A generalization of median filtering using linear combinations of order statistics
TL;DR: In this paper, the authors consider a class of nonlinear filters whose output is given by a linear combination of the order statistics of the input sequence, and choose the coefficients in the linear combination to minimize the output MSE for several noise distributions.
Journal ArticleDOI
Median filtering by threshold decomposition
TL;DR: It is shown that median filtering an arbitrary level signal to its root is equivalent to decomposing the signal into binary signals, filtering each binary signal to a root with a binary median filter, and then reversing the decomposition.