--- /dev/null
+## Copyright (C) 2000 Teemu Ikonen
+##
+## This program is free software; you can redistribute it and/or
+## modify it under the terms of the GNU General Public License
+## as published by the Free Software Foundation; either version 2
+## of the License, or (at your option) any later version.
+##
+## This program is distributed in the hope that it will be useful, but
+## WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+## General Public License for more details.
+##
+## You should have received a copy of the GNU General Public License
+## along with this program; If not, see <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {} impad(@var{A}, @var{xpad}, @var{ypad}, [@var{padding}, [@var{const}]])
+## Pad (augment) a matrix for application of image processing algorithms.
+##
+## Pads the input image @var{A} with @var{xpad}(1) elements from left,
+## @var{xpad}(2), elements from right, @var{ypad}(1) elements from above
+## and @var{ypad}(2) elements from below.
+## Values of padding elements are determined from the optional arguments
+## @var{padding} and @var{const}. @var{padding} is one of
+##
+## @table @samp
+## @item "zeros"
+## pad with zeros (default)
+##
+## @item "ones"
+## pad with ones
+##
+## @item "constant"
+## pad with a value obtained from the optional fifth argument const
+##
+## @item "symmetric"
+## pad with values obtained from @var{A} so that the padded image mirrors
+## @var{A} starting from edges of @var{A}
+##
+## @item "reflect"
+## same as symmetric, but the edge rows and columns are not used in the padding
+##
+## @item "replicate"
+## pad with values obtained from A so that the padded image
+## repeates itself in two dimensions
+##
+## @end table
+## @end deftypefn
+
+## Author: Teemu Ikonen <tpikonen@pcu.helsinki.fi>
+## Created: 5.5.2000
+## Keywords: padding image processing
+
+## A nice test matrix for padding:
+## A = 10*[1:5]' * ones(1,5) + ones(5,1)*[1:5]
+
+function retim = impad(im, xpad, ypad, padding = "zeros", const = 1)
+ ## Input checking
+ if (!ismatrix(im) || ndims(im) < 2 || ndims(im) > 3)
+ error("impad: first input argument must be an image");
+ endif
+ if (isscalar(xpad) && xpad >= 0)
+ xpad(2) = xpad;
+ elseif (!isreal(xpad) || numel(xpad) != 2 || any(xpad < 0))
+ error("impad: xpad must be a positive scalar or 2-vector");
+ endif
+ if (isscalar(ypad) && ypad >= 0)
+ ypad(2) = ypad;
+ elseif (!isreal(ypad) || numel(ypad) != 2 || any(ypad < 0))
+ error("impad: ypad must be a positive scalar or 2-vector");
+ endif
+ if (!isscalar(const))
+ error("impad: fifth input argument must be a scalar");
+ endif
+
+ origx = size(im,2);
+ origy = size(im,1);
+ retx = origx + xpad(1) + xpad(2);
+ rety = origy + ypad(1) + ypad(2);
+ cl = class(im);
+
+ for iter = size(im,3):-1:1
+ A = im(:,:,iter);
+ switch (lower(padding))
+ case "zeros"
+ retval = zeros(rety, retx, cl);
+ retval(ypad(1)+1 : ypad(1)+origy, xpad(1)+1 : xpad(1)+origx) = A;
+ case "ones"
+ retval = ones(rety, retx, cl);
+ retval(ypad(1)+1 : ypad(1)+origy, xpad(1)+1 : xpad(1)+origx) = A;
+ case "constant"
+ retval = const.*ones(rety, retx, cl);
+ retval(ypad(1)+1 : ypad(1)+origy, xpad(1)+1 : xpad(1)+origx) = A;
+ case "replicate"
+ y1 = origy-ypad(1)+1;
+ x1 = origx-xpad(1)+1;
+ if (y1 < 1 || x1 < 1 || ypad(2) > origy || xpad(2) > origx)
+ error("impad: too large padding for this padding type");
+ else
+ yrange1 = y1:origy;
+ yrange2 = 1:ypad(2);
+ xrange1 = x1:origx;
+ xrange2 = 1:xpad(2);
+ retval = [ A(yrange1, xrange1), A(yrange1, :), A(yrange1, xrange2);
+ A(:, xrange1), A, A(:, xrange2);
+ A(yrange2, xrange1), A(yrange2, :), A(yrange2, xrange2) ];
+ endif
+ case "symmetric"
+ y2 = origy-ypad(2)+1;
+ x2 = origx-xpad(2)+1;
+ if (ypad(1) > origy || xpad(1) > origx || y2 < 1 || x2 < 1)
+ error("impad: too large padding for this padding type");
+ else
+ yrange1 = 1 : ypad(1);
+ yrange2 = y2 : origy;
+ xrange1 = 1 : xpad(1);
+ xrange2 = x2 : origx;
+ retval = [ fliplr(flipud(A(yrange1, xrange1))), flipud(A(yrange1, :)), fliplr(flipud(A(yrange1, xrange2)));
+ fliplr(A(:, xrange1)), A, fliplr(A(:, xrange2));
+ fliplr(flipud(A(yrange2, xrange1))), flipud(A(yrange2, :)), fliplr(flipud(A(yrange2, xrange2))) ];
+ endif
+ case "reflect"
+ y2 = origy-ypad(2);
+ x2 = origx-xpad(2);
+ if (ypad(1)+1 > origy || xpad(1)+1 > origx || y2 < 1 || x2 < 1)
+ error("impad: too large padding for this padding type");
+ else
+ yrange1 = 2 : ypad(1)+1;
+ yrange2 = y2 : origy-1;
+ xrange1 = 2 : xpad(1)+1;
+ xrange2 = x2 : origx-1;
+ retval = [ fliplr(flipud(A(yrange1, xrange1))), flipud(A(yrange1, :)), fliplr(flipud(A(yrange1, xrange2)));
+ fliplr(A(:, xrange1)), A, fliplr(A(:, xrange2));
+ fliplr(flipud(A(yrange2, xrange1))), flipud(A(yrange2, :)), fliplr(flipud(A(yrange2, xrange2))) ];
+ endif
+ otherwise
+ error("impad: unknown padding type");
+ endswitch
+
+ retim(:,:,iter) = retval;
+ endfor
+endfunction
git://git.creatis.insa-lyon.fr / CreaPhase.git / blobdiff