ordfilt2.m

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function varargout = ordfilt2(varargin)
%ORDFILT2 Perform 2-D order-statistic filtering.
%   Y=ORDFILT2(X,ORDER,DOMAIN) replaces each element in X by the
%   ORDER-th element in the sorted set of neighbors specified by
%   the nonzero elements in DOMAIN.  
%
%   Y = ORDFILT2(X,ORDER,DOMAIN,S), where S is the same size as
%   DOMAIN, uses the values of S corresponding to the nonzero
%   values of DOMAIN as additive offsets.
%
%   Class Support
%   -------------
%   The class of X may be double or uint8. The class of Y is the
%   same as the class of X, unless the additive offset form of
%   ORDFILT2 is used, in which case the class of Y is double.
%
%   Remarks
%   -------
%   DOMAIN is equivalent to the structuring element used for
%   binary image operations. It is a matrix containing only 1's
%   and 0's; the 1's define the neighborhood for the filtering
%   operation.
%
%   For example, Y=ORDFILT2(X,5,ONES(3,3)) implements a 3-by-3
%   median filter; Y=ORDFILT2(X,1,ONES(3,3)) implements a 3-by-3
%   minimum filter; and Y=ORDFILT2(X,9,ONES(3,3)) implements a
%   3-by-3 maximum filter.  Y=ORDFILT2(X,4,[0 1 0; 1 0 1; 0 1 0])
%   replaces each element in X by the maximum of its north, east,
%   south, and west neighbors. 
%
%   The syntax that includes S (the matrix of additive offsets)
%   can be used to implement grayscale morphological operations,
%   including grayscale dilation and erosion.
%
%   See also MEDFILT2.

%   Steven L. Eddins, 8 December 1994
%   Copyright 1993-1998 The MathWorks, Inc.  All Rights Reserved.
%   $Revision: 5.6 $  $Date: 1997/11/24 15:36:01 $

error('Missing MEX-file ORDFILT2');