www.gusucode.com > matlab非局部均值工具箱 > matlab非局部均值工具箱/matlab非局部均值工具箱/toolbox_nlmeans/toolbox/ordfilt2/padarray.m
function b = padarray(varargin)
%PADARRAY Pad an array.
% B = PADARRAY(A,PADSIZE) pads array A with PADSIZE(k) number of zeros
% along the k-th dimension of A. PADSIZE should be a vector of
% positive integers.
%
% B = PADARRAY(A,PADSIZE,PADVAL) pads array A with PADVAL (a scalar)
% instead of with zeros.
%
% B = PADARRAY(A,PADSIZE,PADVAL,DIRECTION) pads A in the direction
% specified by the string DIRECTION. DIRECTION can be one of the
% following strings.
%
% String values for DIRECTION
% 'pre' Pads before the first array element along each
% dimension .
% 'post' Pads after the last array element along each
% dimension.
% 'both' Pads before the first array element and after the
% last array element along each dimension.
%
% By default, DIRECTION is 'both'.
%
% B = PADARRAY(A,PADSIZE,METHOD,DIRECTION) pads array A using the
% specified METHOD. METHOD can be one of these strings:
%
% String values for METHOD
% 'circular' Pads with circular repetion of elements.
% 'replicate' Repeats border elements of A.
% 'symmetric' Pads array with mirror reflections of itself.
%
% Class Support
% -------------
% When padding with a constant value, A can be numeric or logical.
% When padding using the 'circular', 'replicate', or 'symmetric'
% methods, A can be of any class. B is of the same class as A.
%
% Example
% -------
% Add three elements of padding to the beginning of a vector. The
% padding elements contain mirror copies of the array.
%
% b = padarray([1 2 3 4],3,'symmetric','pre')
%
% Add three elements of padding to the end of the first dimension of
% the array and two elements of padding to the end of the second
% dimension. Use the value of the last array element as the padding
% value.
%
% B = padarray([1 2; 3 4],[3 2],'replicate','post')
%
% Add three elements of padding to each dimension of a
% three-dimensional array. Each pad element contains the value 0.
%
% A = [1 2; 3 4];
% B = [5 6; 7 8];
% C = cat(3,A,B)
% D = padarray(C,[3 3],0,'both')
%
% See also CIRCSHIFT, IMFILTER.
% Copyright 1993-2003 The MathWorks, Inc.
% $Revision: 1.11.4.3 $ $Date: 2003/08/23 05:53:08 $
[a, method, padSize, padVal, direction] = ParseInputs(varargin{:});
if isempty(a),% treat empty matrix similar for any method
if strcmp(direction,'both')
sizeB = size(a) + 2*padSize;
else
sizeB = size(a) + padSize;
end
b = mkconstarray(class(a), padVal, sizeB);
else
switch method
case 'constant'
b = ConstantPad(a, padSize, padVal, direction);
case 'circular'
b = CircularPad(a, padSize, direction);
case 'symmetric'
b = SymmetricPad(a, padSize, direction);
case 'replicate'
b = ReplicatePad(a, padSize, direction);
end
end
if (islogical(a))
b = logical(b);
end
%%%
%%% ConstantPad
%%%
function b = ConstantPad(a, padSize, padVal, direction)
numDims = numel(padSize);
% Form index vectors to subsasgn input array into output array.
% Also compute the size of the output array.
idx = cell(1,numDims);
sizeB = zeros(1,numDims);
for k = 1:numDims
M = size(a,k);
switch direction
case 'pre'
idx{k} = (1:M) + padSize(k);
sizeB(k) = M + padSize(k);
case 'post'
idx{k} = 1:M;
sizeB(k) = M + padSize(k);
case 'both'
idx{k} = (1:M) + padSize(k);
sizeB(k) = M + 2*padSize(k);
end
end
% Initialize output array with the padding value. Make sure the
% output array is the same type as the input.
b = mkconstarray(class(a), padVal, sizeB);
b(idx{:}) = a;
%%%
%%% CircularPad
%%%
function b = CircularPad(a, padSize, direction)
numDims = numel(padSize);
% Form index vectors to subsasgn input array into output array.
% Also compute the size of the output array.
idx = cell(1,numDims);
for k = 1:numDims
M = size(a,k);
dimNums = 1:M;
p = padSize(k);
switch direction
case 'pre'
idx{k} = dimNums(mod(-p:M-1, M) + 1);
case 'post'
idx{k} = dimNums(mod(0:M+p-1, M) + 1);
case 'both'
idx{k} = dimNums(mod(-p:M+p-1, M) + 1);
end
end
b = a(idx{:});
%%%
%%% SymmetricPad
%%%
function b = SymmetricPad(a, padSize, direction)
numDims = numel(padSize);
% Form index vectors to subsasgn input array into output array.
% Also compute the size of the output array.
idx = cell(1,numDims);
for k = 1:numDims
M = size(a,k);
dimNums = [1:M M:-1:1];
p = padSize(k);
switch direction
case 'pre'
idx{k} = dimNums(mod(-p:M-1, 2*M) + 1);
case 'post'
idx{k} = dimNums(mod(0:M+p-1, 2*M) + 1);
case 'both'
idx{k} = dimNums(mod(-p:M+p-1, 2*M) + 1);
end
end
b = a(idx{:});
%%%
%%% ReplicatePad
%%%
function b = ReplicatePad(a, padSize, direction)
numDims = numel(padSize);
% Form index vectors to subsasgn input array into output array.
% Also compute the size of the output array.
idx = cell(1,numDims);
for k = 1:numDims
M = size(a,k);
p = padSize(k);
onesVector = ones(1,p);
switch direction
case 'pre'
idx{k} = [onesVector 1:M];
case 'post'
idx{k} = [1:M M*onesVector];
case 'both'
idx{k} = [onesVector 1:M M*onesVector];
end
end
b = a(idx{:});
%%%
%%% ParseInputs
%%%
function [a, method, padSize, padVal, direction] = ParseInputs(varargin)
% default values
a = [];
method = 'constant';
padSize = [];
padVal = 0;
direction = 'both';
% checknargin(2,4,nargin,mfilename);
a = varargin{1};
padSize = varargin{2};
% checkinput(padSize, {'double'}, {'real' 'vector' 'nonnan' 'nonnegative' ...
% 'integer'}, mfilename, 'PADSIZE', 2);
% Preprocess the padding size
if (numel(padSize) < ndims(a))
padSize = padSize(:);
padSize(ndims(a)) = 0;
end
if nargin > 2
firstStringToProcess = 3;
if ~ischar(varargin{3})
% Third input must be pad value.
padVal = varargin{3};
% checkinput(padVal, {'numeric' 'logical'}, {'scalar'}, ...
% mfilename, 'PADVAL', 3);
firstStringToProcess = 4;
end
for k = firstStringToProcess:nargin
validStrings = {'circular' 'replicate' 'symmetric' 'pre' ...
'post' 'both'};
string = checkstrs(varargin{k}, validStrings, mfilename, ...
'METHOD or DIRECTION', k);
switch string
case {'circular' 'replicate' 'symmetric'}
method = string;
case {'pre' 'post' 'both'}
direction = string;
otherwise
error('Images:padarray:unexpectedError', '%s', ...
'Unexpected logic error.')
end
end
end
% Check the input array type
if strcmp(method,'constant') && ~(isnumeric(a) || islogical(a))
id = sprintf('Images:%s:badTypeForConstantPadding', mfilename);
msg1 = sprintf('Function %s expected A (argument 1)',mfilename);
msg2 = 'to be numeric or logical for constant padding.';
error(id,'%s\n%s',msg1,msg2);
end