几种经典的图像平滑去噪算法程序

function b = meanfilt2(varargin) %MEDFILT2 Perform 2-D median filtering. % B = MEDFILT2(A,[M N]) performs median filtering of the matrix % A in two dimensions. Each output pixel contains the median % value in the M-by-N neighborhood around the corresponding % pixel in the input image. MEDFILT2 pads the image with zeros % on the edges, so the median values for the points within % [M N]/2 of the edges may appear distorted. % % B = MEDFILT2(A) performs median filtering of the matrix A % using the default 3-by-3 neighborhood. % % B = MEDFILT2(...,PADOPT) controls how the matrix boundaries % are padded. PADOPT may be 'zeros' (the default), % 'symmetric', or 'indexed'. If PADOPT is 'zeros', A is padded % with zeros at the boundaries. If PADOPT is 'symmetric', A is % symmetrically extended at the boundaries. If PADOPT is % 'indexed', A is padded with ones if it is double; otherwise % it is padded with zeros. % % Class Support % ------------- % The input image A can be logical or numeric (unless the % 'indexed' syntax is used, in which case A cannot be of class % uint16). The output image B is of the same class as A. % % Remarks % ------- % If the input image A is of integer class, all of the output % values are returned as integers. If the number of % pixels in the neighborhood (i.e., M*N) is even, some of the % median values may not be integers. In these cases, the % fractional parts are discarded. Logical input is treated % similarly. % % Example % ------- % I = imread('eight.tif'); % J = imnoise(I,'salt & pepper',0.02); % K = medfilt2(J); % imview(J), imview(K) % % See also FILTER2, ORDFILT2, WIENER2. % Copyright 1993-2003 The MathWorks, Inc. % $Revision: 5.22 $ $Date: 2003/01/27 20:16:04 $ [a, mn, padopt] = parse_inputs(varargin{:}); domain = ones(mn); if (rem(prod(mn), 2) == 1) order = (prod(mn)+1)/2; b = ordfilt2(a, order, domain, padopt); else order1 = prod(mn)/2; order2 = order1+1; b = ordfilt2(a, order1, domain, padopt); b2 = ordfilt2(a, order2, domain, padopt); idx = find(b ~= b2); b(idx) = (double(b(idx)) + double(b2(idx)))/2; end %%% %%% Function parse_inputs %%% function [a, mn, padopt] = parse_inputs(varargin) checknargin(1,4,nargin,mfilename); % There are several grandfathered syntaxes we have to catch % and parse successfully, so we're going to use a strategy % that's a little different that usual. % % First, scan the input argument list for strings. The % string 'indexed', 'zeros', or 'symmetric' can appear basically % anywhere after the first argument. % % Second, delete the strings from the argument list. % % The remaining argument list can be one of the following: % MEDFILT2(A) % MEDFILT2(A,[M N]) % MEDFILT2(A,[M N],[Mb Nb]) % % Any syntax in which 'indexed' is followed by other arguments % is grandfathered. Any syntax in which [Mb Nb] appears is % grandfathered. % % -sle, March 1998 a = varargin{1}; charLocation = []; for k = 2:nargin if (ischar(varargin{k})) charLocation = [charLocation k]; end end if (length(charLocation) > 1) % More than one string in input list eid = 'Images:medfilt2:tooManyStringInputs'; error(eid,'%s','Too many input string arguments.'); elseif (length(charLocation) == 0) % No string specified padopt = 'zeros'; else options = {'indexed', 'zeros', 'symmetric'}; padopt = checkstrs(varargin{charLocation}, options, mfilename, ... 'PADOPT', charLocation); varargin(charLocation) = []; end if (strcmp(padopt, 'indexed')) if (isa(a,'double')) padopt = 'ones'; else padopt = 'zeros'; end end if length(varargin) == 1, mn = [3 3];% default elseif length(varargin) >= 2, mn = varargin{2}(:).'; if size(mn,2)~=2, msg = 'MEDFILT2(A,[M N]): Second argument must consist of two integers.'; eid = 'Images:medfilt2:secondArgMustConsistOfTwoInts'; error(eid, msg); elseif length(varargin) > 2, msg = ['MEDFILT2(A,[M N],[Mb Nb],...) is an obsolete syntax. [Mb Nb]' ... ' argument is ignored.']; wid = 'Images:medfilt2:obsoleteSyntax'; warning(wid, msg); end end % The grandfathered [Mb Nb] argument, if present, is ignored.