Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / image-1.0.15 / bestblk.m

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+## 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{siz} = } bestblk ([@var{m} @var{n}], @var{k})
+## @deftypefnx {Function File} {[@var{mb} @var{nb}] = } bestblk ([@var{m} @var{n}], @var{k})
+## Calculates the best size of block for block processing.
+##
+## @code{siz=bestblk([m,n],k)} calculates the optimal block size for block
+## processing for a @var{m}-by-@var{n} image. @var{k} is the maximum
+## side dimension of the block. Its default value is 100. @var{siz} is a
+## row vector which contains row and column dimensions for the block.
+##
+## @code{[mb,nb]=bestblk([m,n],k)} behaves as described above but
+## returns block dimensions to @var{mb} and @var{nb}.
+##
+## @strong{Algorithm:}
+##
+## For each dimension (@var{m} and @var{n}), it follows this algorithm:
+##
+## 1.- If dimension is less or equal than @var{k}, it returns the
+## dimension value.
+##
+## 2.- If not then returns the value between
+## @code{round(min(dimension/10,k/2))} which minimizes padding.
+##
+##
+## @seealso{blkproc}
+## @end deftypefn
+
+
+## Author:  Josep Mones i Teixidor <jmones@puntbarra.com>
+
+function [varargout] = bestblk(ims,k)
+  if(nargin<1 || nargin>2)
+    usage("siz=bestblk([m,n],k), [mb,nb]=bestblk([m,n],k)");
+  endif
+  if(nargout>2)
+    usage("siz=bestblk([m,n],k), [mb,nb]=bestblk([m,n],k)");
+  endif
+  if(nargin<2)
+    k=100;
+  endif
+  if(!isvector(ims))
+    error("bestblk: first parameter is not a vector.");
+  endif
+  ims=ims(:);
+  if(length(ims)!=2)
+    error("bestblk: length of first parameter is not 2.");
+  endif
+
+  mb=mi=ims(1);
+  p=mi;
+  if(mi>k)
+    for i=round(min(mi/10,k/2)):k
+      pt=rem(mi,i);
+      if(pt<p)
+       p=pt;
+       mb=i;
+      endif
+    endfor
+  endif
+
+  nb=ni=ims(2);
+  p=ni;
+  if(ni>k)
+    for i=round(min(ni/10,k/2)):k
+      pt=rem(ni,i);
+      if(pt<p)
+       p=pt;
+       nb=i;
+      endif
+    endfor
+  endif
+
+  if(nargout<=1)
+    varargout{1}=[mb;nb];
+  else
+    varargout{1}=mb;
+    varargout{2}=nb;
+  endif
+
+endfunction
+
+%!demo
+%! siz = bestblk ([200; 10], 50);
+%! disp (siz)
+
+%!assert(bestblk([300;100],150),[30;100]);
+%!assert(bestblk([256,128],17),[16;16]);
+
+% $Log$
+% Revision 1.3  2007/03/23 16:14:36  adb014
+% Update the FSF address
+%
+% Revision 1.2  2007/01/04 23:44:22  hauberg
+% Minor changes in help text
+%
+% Revision 1.1  2006/08/20 12:59:31  hauberg
+% Changed the structure to match the package system
+%
+% Revision 1.2  2005/07/03 01:10:19  pkienzle
+% Try to correct for missing newline at the end of the file
+%
+% Revision 1.1  2004/08/15 19:01:05  jmones
+% bestblk added: Calculates best block size for block processing