--- /dev/null
+## Copyright (C) 2004 Josep Mones i Teixidor
+##
+## 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} {@var{A} = } col2im (@var{B}, [@var{m},@var{n}], [@var{mm},@var{nn}], @var{block_type})
+## @deftypefnx {Function File} {@var{A} = } col2im (@var{B}, [@var{m},@var{n}], [@var{mm},@var{nn}])
+## Rearranges matrix columns into blocks.
+##
+## @code{A=col2im(B,[m,n],[mm,nn],block_type)} rearranges columns of
+## matrix @var{B} intro blocks in a way controlled by @var{block_type}
+## param, which can take the following values:
+##
+## @table @code
+## @item distinct
+## It uses @var{m}-by-@var{n} distinct blocks (which are not
+## overlapped), and are rearranged to form a @var{mm}-by-@var{nn} matrix
+## @var{A}. @var{B}'s height must be @var{m}*@var{n} and @code{col2im}
+## rearranges each column to a @var{m}-by-@var{n} block and uses them to
+## fill the whole matrix in left-to-right and then up-to-down order.
+## @item sliding
+## Is uses @var{m}-by-@var{n} sliding blocks. It rearranges row vector
+## @var{B} to a (@var{mm}-@var{m}+1)-by-(@var{nn}-@var{n}+1) matrix
+## @var{A}. @var{B} must be a
+## 1-by-(@var{mm}-@var{m}+1)*(@var{nn}-@var{n}+1).
+## @end table
+##
+## @code{A=col2im(B,[m,n],[mm,nn])} takes @code{distinct} as a default
+## value for @var{block_type}.
+##
+## @seealso{im2col}
+## @end deftypefn
+
+## Author: Josep Mones i Teixidor <jmones@puntbarra.com>
+
+function A = col2im(B, sblock, sb, block_type)
+ if(nargin<3 || nargin>4)
+ usage("A=col2im(B, [m,n], [mm,nn] [, block_type])");
+ endif
+
+ if(nargin!=4)
+ block_type='sliding';
+ endif
+
+ ## common checks
+ if(!ismatrix(B))
+ error("col2im: B should be a matrix (or vector).");
+ endif
+ if(!isvector(sblock) || length(sblock)!=2)
+ error("col2im: expected [m,n] as second parameter.");
+ endif
+ if(!isvector(sb) || length(sb)!=2)
+ error("col2im: expected [mm,nn] as third parameter.");
+ endif
+
+ m=sblock(1);
+ n=sblock(2);
+ mm=sb(1);
+ nn=sb(2);
+
+ switch(block_type)
+ case('distinct')
+ if(rows(B)!=m*n)
+ error("col2im: B height must be m*n for 'distinct' block_type.");
+ endif
+ if(rem(mm,m)!=0)
+ error("col2im: mm should be multiple of m");
+ endif
+ if(rem(nn,n)!=0)
+ error("col2im: nn should be multiple of n");
+ endif
+ mt=mm/m;
+ nt=nn/n;
+ if(columns(B)<mt*nt)
+ error("col2im: B's width is too small (should be mm*nn/(m*m)).");
+ endif
+ c=1;
+ for i=1:mt
+ ## TODO: check if we can horzcat([],uint8([10;11])) in a
+ ## future Octave version > 2.1.58 in order to deuglify this!
+ r=reshape(B(:,c),m,n);
+ c+=1;
+ for j=2:nt
+ r=horzcat(r, reshape(B(:,c),m,n));
+ c+=1;
+ endfor
+ if(i==1) ## this workarrounds a bug in ver<=2.1.57 cat implementation
+ A=r;
+ else
+ A=vertcat(A,r);
+ endif
+ endfor
+
+ case('sliding')
+ if(!all(size(B)==[1,(mm-m+1)*(nn-n+1)]))
+ error("col2im: wrong B size. Should be 1-by-(mm-m+1)*(nn-n+1).");
+ endif
+ A=reshape(B, mm-m+1, nn-n+1);
+
+ otherwise
+ error("col2im: invalid block_type.");
+ endswitch
+
+endfunction
+
+%!demo
+%! A=[1:10;11:20;21:30;31:40]
+%! B=im2col(A,[2,5],'distinct')
+%! C=col2im(B,[2,5],[4,10],'distinct')
+%! # Divide A using distinct blocks and reverse operation
+
+
+%!shared B, Ad
+%! v=[1:10]';
+%! r=reshape(v,2,5);
+%! B=[v, v+10, v+20, v+30, v+40, v+50];
+%! Ad=[r, r+10; r+20, r+30; r+40, r+50];
+
+%!# bad m
+%!error(col2im(B,[3,5],[6,10],'distinct'));
+
+%!# bad n
+%!error(col2im(B,[2,3],[6,10],'distinct'));
+
+%!# bad mm
+%!error(col2im(B,[2,5],[7,10],'distinct'));
+
+%!# bad nn
+%!error(col2im(B,[2,5],[6,11],'distinct'));
+
+%!# bad block_type
+%!error(col2im(B,[2,5],[6,10],'wrong_block_type'));
+
+%!# this should be ok
+%!assert(col2im(B,[2,5],[6,10],'distinct'), Ad);
+
+%!# now sliding
+%!assert(col2im(ones(1,(10-2+1)*(7-3+1)),[2,3],[10,7]), ones((10-2+1),(7-3+1)));
+%!assert(col2im(ones(1,(10-2+1)*(7-3+1)),[2,3],[10,7],'sliding'), ones((10-2+1),(7-3+1)));
+
+
+%!# disctint on uint8
+%!assert(col2im(uint8(B),[2,5],[6,10],'distinct'), uint8(Ad));
+
+%!# now sliding on uint8
+%!assert(col2im(ones(1,(10-2+1)*(7-3+1),"uint8"),[2,3],[10,7]), ones((10-2+1),(7-3+1),"uint8"));
+
+
+%
+% $Log$
+% Revision 1.4 2007/03/23 16:14:36 adb014
+% Update the FSF address
+%
+% Revision 1.3 2007/01/04 23:46:17 hauberg
+% Minor changes in help text
+%
+% Revision 1.2 2007/01/04 23:37:54 hauberg
+% Minor changes in help text
+%
+% Revision 1.1 2006/08/20 12:59:32 hauberg
+% Changed the structure to match the package system
+%
+% Revision 1.2 2004/09/03 17:57:42 jmones
+% Added support for int* and uint* types
+%
+% Revision 1.1 2004/08/18 14:39:07 jmones
+% im2col and col2im added
+%
+%
git://git.creatis.insa-lyon.fr / CreaPhase.git / blobdiff