comparison util/ksvd utils/im2colstep.m @ 70:c3eca463202d

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author idamnjanovic
date Wed, 16 Mar 2011 14:16:57 +0000
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69:5f1f436057ca 70:c3eca463202d
1 %IM2COLSTEP Rearrange matrix blocks into columns.
2 % B = IM2COLSTEP(A,[N1 N2]) converts each sliding N1-by-N2 block of the
3 % 2-D matrix A into a column of B, with no zero padding. B has N1*N2 rows
4 % and will contain as many columns as there are N1-by-N2 neighborhoods in
5 % A. Each column of B contains a neighborhood of A reshaped as NHOOD(:),
6 % where NHOOD is a matrix containing an N1-by-N2 neighborhood of A.
7 %
8 % B = IM2COLSTEP(A,[N1 N2],[S1 S2]) extracts neighborhoods of A with a
9 % step size of (S1,S2) between them. The first extracted neighborhood is
10 % A(1:N1,1:N2), and the rest are of the form A((1:N1)+i*S1,(1:N2)+j*S2).
11 % Note that to ensure coverage of all A by neighborhoods,
12 % (size(A,i)-Ni)/Si must be whole for i=1,2. The default function behavior
13 % corresponds to [S1 S2] = [1 1]. Setting S1>=N1 and S2>=N2 results in no
14 % overlap between the neighborhoods.
15 %
16 % B = IM2COLSTEP(A,[N1 N2 N3],[S1 S2 S3]) operates on a 3-D matrix A. The
17 % step size [S1 S2 S3] may be ommitted, and defaults to [1 1 1].
18 %
19 % Note: the call IM2COLSTEP(A,[N1 N2]) produces the same output as
20 % Matlab's IM2COL(A,[N1 N2],'sliding'). However, it is significantly
21 % faster.
22 %
23 % See also COL2IMSTEP, IM2COL, COUNTCOVER.
24
25
26 % Ron Rubinstein
27 % Computer Science Department
28 % Technion, Haifa 32000 Israel
29 % ronrubin@cs
30 %
31 % August 2009