diff Problems/private/countcover.m @ 10:207a6ae9a76f version1.0

(none)

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Problems/private/countcover.m	Mon Mar 22 15:06:25 2010 +0000
@@ -0,0 +1,31 @@
+function cnt = countcover(sz,blocksize,stepsize)
+%COUNTCOVER Covering of signal samples by blocks
+%  CNT = COUNTCOVER(SZ,BLOCKSIZE,STEPSIZE) assumes a p-dimensional signal
+%  of size SZ=[N1 N2 ... Np] covered by (possibly overlapping) blocks of
+%  size BLOCKSIZE=[M1 M2 ... Mp]. The blocks start at position (1,1,..,1)
+%  and are shifted between them by steps of size STEPSIZE=[S1 S2 ... Sp].
+%  COUNTCOVER returns a matrix the same size as the signal, containing in
+%  each entry the number of blocks covering that sample.
+
+
+%  Ron Rubinstein
+%  Computer Science Department
+%  Technion, Haifa 32000 Israel
+%  ronrubin@cs
+%
+%  August 2008
+
+
+cnt = ones(sz);
+for k = 1:length(sz)
+  
+  % this code is modified from function NDGRID, so it computes one
+  % output argument of NDGRID at a time (to conserve memory)
+  ids = (1:sz(k))';
+  s = sz; s(k) = [];
+  ids = reshape(ids(:,ones(1,prod(s))),[length(ids) s]);
+  ids = permute(ids,[2:k 1 k+1:length(sz)]);
+  
+  cnt = cnt .* max( min(floor((ids-1)/stepsize(k)),floor((sz(k)-blocksize(k))/stepsize(k))) - ...
+                    max(ceil((ids-blocksize(k))/stepsize(k)),0) + 1 , 0 );
+end