--- /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{S} = } qtdecomp (@var{I})
+## @deftypefnx {Function File} {@var{S} = } qtdecomp (@var{I},@var{threshold})
+## @deftypefnx {Function File} {@var{S} = } qtdecomp (@var{I},@var{threshold},@var{mindim})
+## @deftypefnx {Function File} {@var{S} = } qtdecomp (@var{I},@var{threshold},@var{[mindim maxdim]})
+## @deftypefnx {Function File} {@var{S} = } qtdecomp (@var{I},@var{fun})
+## @deftypefnx {Function File} {@var{S} = } qtdecomp (@var{I},@var{fun},@var{P1},@var{P2},...)
+## Performs quadtree decomposition.
+##
+## qtdecomp decomposes a square image @var{I} into four equal-sized
+## blocks. Then it performs some kind of test on each block to decide if
+## it should decompose them further. This process is repeated
+## iteratively until there's no block left to be decomposed.
+##
+## Note that blocks are not decomposed if their dimensions are not even.
+##
+## The output is a sparse matrix whose non-zero elements determine the
+## position of the block (the element is at top-left position in the
+## block) and size of each block (the value of the element determines
+## length of a side of the square-shaped block).
+##
+## S = qtdecomp(I) decomposes an intensity image @var{I} as described
+## above. By default it doesn't split a block if all elements are equal.
+##
+## S = qtdecomp(I, threshold) decomposes an image as decribed, but only
+## splits a block if the maximum value in the block minus the minimum
+## value is greater than @var{threshold}, which is a value between 0 and
+## 1. If @var{I} is of class uint8, @var{threshold} is multiplied by 255
+## before use. Also, if@var{I} is of class uint16, @var{threshold} is
+## multiplied by 65535.
+##
+## S = qtdecomp(I, threshold, mindim) decomposes an image using the
+## @var{threshold} as just described, but doesn't produce blocks smaller
+## than mindim.
+##
+## S = qtdecomp(I, threshold, [mindim maxdim]) decomposes an image as
+## described, but produces blocks that can't be bigger than maxdim. It
+## decomposes to maxdim even if it isn't needed if only @var{threshold}
+## was considered.
+##
+## S = qtdecomp(I, fun) decomposes an image @var{I} and uses function
+## @var{fun} to decide if a block should be splitted or not. @var{fun}
+## is called with a m-by-m-by-k array of m-by-m blocks to be
+## considered, and should return a vector of size k, whose elements
+## represent each block in the stacked array. @var{fun} sets the
+## corresponding value to 1 if the block should be split, and 0
+## otherwise.
+##
+## S = qtdecomp(I, fun, ...) behaves as qtdecomp(I, fun) but passes
+## extra parameters to @var{fun}.
+##
+## @seealso{qtgetblk, qtsetblk}
+## @end deftypefn
+
+## Author: Josep Mones i Teixidor <jmones@puntbarra.com>
+
+function S = qtdecomp(I, p1, varargin)
+ if (nargin<1)
+ usage("S=qtdecomp(I)");
+ endif
+
+ if (!ismatrix(I) || size(I,1)!=size(I,2))
+ error("qtdecomp: I should be a square matrix.");
+ endif
+
+ ## current size (assumed to be square)
+ curr_size=size(I,1);
+
+ ## initial mindim to a sensible value
+ mindim=1;
+
+ ## sensible default maxdim value
+ maxdim=curr_size;
+
+ if (nargin<2)
+ ## Initialize decision method variable
+ ## We could have implemented threshold as a function and use an
+ ## uniform interface (function handle) to decide whether to split or
+ ## not blocks. We have decided not to do so because block
+ ## rearrangement that is needed as a parameter to functions is
+ ## expensive.
+ decision_method=0;
+ elseif (isreal(p1))
+ ## p1 is threshold
+ threshold=p1;
+ decision_method=1;
+
+ if(strcmp(typeinfo(I), 'uint8 matrix'))
+ threshold*=255;
+ elseif(strcmp(typeinfo(I), 'uint16 matrix'))
+ threshold*=65535;
+ endif
+
+ if (nargin>3)
+ usage("S=qtdecomp(I,threshold,mindim), \
+ S=qtdecomp(I,threshold,[mindim maxdim])");
+ elseif (nargin==3)
+ dims=varargin{1};
+ if (isvector(dims)&&length(dims)==2)
+ mindim=dims(1);
+ maxdim=dims(2);
+ elseif (isreal(dims))
+ mindim=dims;
+ else
+ error("qtdecomp: third parameter must be 'mindim' or '[mindim maxdim]'");
+ endif
+ ## we won't check if mindim or maxdim are powers of 2. It's too
+ ## restrictive and don't need it at all.
+ endif
+
+ elseif strcmp(typeinfo(p1),"function handle") ...
+ || strcmp(typeinfo(p1),"inline function")
+ ## function handles seem to return true to isscalar
+ fun=p1;
+ decision_method=2;
+ else
+ error("qtdecomp: second parameter must be a integer (threshold) or a function handle (fun).");
+ endif
+
+ ## initialize results matrices
+ res=[];
+
+ ## bool to flag end
+ finished=false;
+
+ ## array of offsets to blocks to evaluate
+ offsets=[1,1];
+
+ if (maxdim<mindim)
+ error("qtdecomp: mindim must be smaller than maxdim.");
+ endif
+
+ ## See if we have to split a minimum regarless other considerations.
+ if (maxdim<curr_size)
+ initial_splits=ceil(log2(curr_size/maxdim));
+ if(initial_splits>0)
+ divs=2^initial_splits;
+ if (rem(curr_size,divs)!=0)
+ error("qtdecomp: Can't decompose I enough times to fulfill maxdim requirement.");
+ endif
+ ## update curr_size
+ curr_size/=divs;
+ if(curr_size<mindim)
+ error("qtdecomp: maxdim restriction collides with mindim restriction.");
+ endif
+ els=([0:divs-1]*curr_size+1).';
+ offsets=[kron(els,ones(divs,1)), kron(ones(divs,1),els)];
+ endif
+ endif
+
+ while(!finished && rows(offsets)>0)
+ ## check other ending conditions:
+ ## is size is odd?
+ ## is splitted size < than mindim?
+ if ((rem(curr_size,2)!=0)||((curr_size/2)<mindim))
+ ## can't continue, lets add current evaluation blocks to results
+ res=[res; offsets, ones(size(offsets,1),1)*curr_size];
+ finished = true;
+ else
+ if (decision_method<2)
+ db=logical(ones(rows(offsets),1));
+ for r=1:rows(offsets)
+ o=offsets(r,:);
+ fo=offsets(r,:)+curr_size-1;
+
+ if(decision_method==0)
+ ## is everything equal?
+ if (all(I(o(1),o(2))==I(o(1):fo(1),o(2):fo(2))))
+ db(r)=0;
+ endif
+ else
+ ## check threshold
+ t=I(o(1):fo(1),o(2):fo(2));
+ t=t(:);
+ if ((max(t)-min(t))<=threshold)
+ db(r)=0;
+ endif
+ endif
+ endfor
+ elseif(decision_method==2)
+ ## function handle decision method
+ ## build blocks
+ b=zeros(curr_size,curr_size,rows(offsets));
+ rbc=offsets(:,1:2)+curr_size-1;
+ for r=1:rows(offsets)
+ b(:,:,r)=I(offsets(r,1):rbc(r,1),offsets(r,2):rbc(r,2));
+ endfor
+
+ db=feval(fun, b, varargin{:});
+ else
+ error("qtdecomp: execution shouldn't reach here. Please report this as a bug.");
+ endif
+
+ ## Add blocks that won't divide to results
+ nd=offsets(find(!db),:);
+ res=[res; nd, ones(size(nd,1),1)*curr_size];
+
+ ## Update curr_size for next iteration
+ curr_size/=2;
+
+ ## Prepare offsets for next iteration
+ otemp=offsets(find(db),:);
+ hs=ones(rows(otemp),1)*curr_size;
+ zs=zeros(size(hs));
+ offsets=[otemp;otemp+[hs,zs];otemp+[zs,hs];otemp+[hs,hs]];
+ endif
+ endwhile
+
+ S=sparse(res(:,1),res(:,2),res(:,3),size(I,1),size(I,2));
+endfunction
+
+
+%!demo
+%! full(qtdecomp(eye(8)))
+%! %It finds 2 big blocks of 0 and it decomposes further where 0 and 1 are mixed.
+
+
+%!# Test if odd-sized limits split
+%!assert(full(qtdecomp(eye(5))), reshape([5,zeros(1,24)],5,5));
+%!assert(full(qtdecomp(eye(6))), repmat(reshape([3,zeros(1,8)],3,3),2,2));
+
+%!# Test 'equal' method
+%!test
+%! a=ones(2,2);
+%! b=[2,0;0,0];
+%! assert(full(qtdecomp(eye(4))), [a,b;b,a]);
+
+%!shared A, B2, B4, f
+%! A=[ 1, 4, 2, 5,54,55,61,62;
+%! 3, 6, 3, 1,58,53,67,65;
+%! 3, 6, 3, 1,58,53,67,65;
+%! 3, 6, 3, 1,58,53,67,65;
+%! 23,42,42,42,99,99,99,99;
+%! 27,42,42,42,99,99,99,99;
+%! 23,22,26,25,99,99,99,99;
+%! 22,22,24,22,99,99,99,99];
+%! B2=[2,0;0,0];
+%! B4=zeros(4); B4(1,1)=4;
+
+%!test
+%! R=[ones(4,8); [ones(2),B2;ones(2,4)], B4];
+%! assert(full(qtdecomp(A)), R);
+%! assert(full(qtdecomp(A,0)), R);
+
+%!# Test 'threshold' method
+%!test
+%! R=[ones(4,8); [ones(2),B2;B2,ones(2)],B4];
+%! assert(full(qtdecomp(A,1)), R);
+
+%!test
+%! R=[[B4,[B2,B2;B2,B2]]; [[ones(2),B2;B2,B2],B4]];
+%! assert(full(qtdecomp(A,10)), R);
+
+%!test
+%! R=[[B4,[B2,B2;B2,B2]]; [[B2,B2;B2,B2],B4]];
+%! assert(full(qtdecomp(A,10,2)), R);
+%!
+%! assert(full(qtdecomp(A,100,[2, 4])), [B4,B4;B4,B4]);
+
+%!test
+%! f = @(A, c1 = 54, c2 = 0, c3 = 0) y = (A (1, 1, :) != ((c1+c2+c3) * ones (1, 1, size (A, 3))))(:);
+%!
+%! assert(full(qtdecomp(A,f)),[ones(4),B4;ones(4,8)]);
+%! assert(full(qtdecomp(A,f,54)),[ones(4),B4;ones(4,8)]);
+%! assert(full(qtdecomp(A,f,4,40,10)),[ones(4),B4;ones(4,8)]);
+
+%!test
+%!# no params
+%! first_eq=inline("(A(1,1,:)!=(54*ones(1,1,size(A,3))))(:)","A");
+%! assert(full(qtdecomp(A,first_eq)),[ones(4),B4;ones(4,8)]);
+
+%!test
+%!# 1 param
+%! first_eq=inline("(A(1,1,:)!=(c*ones(1,1,size(A,3))))(:)","A","c");
+%! assert(full(qtdecomp(A,first_eq,54)),[ones(4),B4;ones(4,8)]);
+
+%!test
+%!# 3 params
+%! first_eq=inline("(A(1,1,:)!=((c1+c2+c3)*ones(1,1,size(A,3))))(:)","A","c1","c2","c3");
+%! assert(full(qtdecomp(A,first_eq,4,40,10)),[ones(4),B4;ones(4,8)]);
+
+
+
+%
+% $Log$
+% Revision 1.5 2007/03/23 16:14:37 adb014
+% Update the FSF address
+%
+% Revision 1.4 2007/01/04 23:50:47 hauberg
+% Put seealso before end deftypefn
+%
+% Revision 1.3 2007/01/04 23:41:47 hauberg
+% Minor changes in help text
+%
+% Revision 1.2 2006/10/09 19:58:09 adb014
+% Remove dependency on miscellaneous transpose function. Simplify tests and add function handle tests
+%
+% Revision 1.1 2006/08/20 12:59:35 hauberg
+% Changed the structure to match the package system
+%
+% Revision 1.8 2006/01/03 02:09:15 pkienzle
+% Reorder tests so that shared variables are displayed unless relevant.
+%
+% Revision 1.7 2006/01/02 22:05:06 pkienzle
+% Reduce number of shared variables in tests
+%
+% Revision 1.6 2004/09/09 19:36:35 jmones
+% all_va_args -> varargin{:}. Now works on 2.1.58
+%
+% Revision 1.5 2004/09/08 14:07:22 pkienzle
+% Fix test for 'inline function'
+%
+% Revision 1.4 2004/08/11 19:52:41 jmones
+% qtsetblk added
+%
+% Revision 1.3 2004/08/11 00:05:21 jmones
+% seealso qtgetblk added to doc
+%
+% Revision 1.2 2004/08/10 00:19:42 jmones
+% Corrected misleading comment.
+%
+% Revision 1.1 2004/08/09 01:48:54 jmones
+% Added qtdecomp: quadtree decomposition
+%
+%
+
git://git.creatis.insa-lyon.fr / CreaPhase.git / blobdiff