open source pkg v1

pkg/OpenFace/matlab_version/fitting/im2col_mine.m

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+function b=im2col_mine(a, block)
+%IM2COL Rearrange image blocks into columns.
+%   B = IM2COL(A,[M N],'distinct') rearranges each distinct
+%   M-by-N block in the image A into a column of B. IM2COL pads A
+%   with zeros, if necessary, so its size is an integer multiple
+%   of M-by-N. If A = [A11 A12; A21 A22], where each Aij is
+%   M-by-N, then B = [A11(:) A21(:) A12(:) A22(:)].
+%
+%   B = IM2COL(A,[M N],'sliding') converts each sliding M-by-N
+%   block of A into a column of B, with no zero padding. B has
+%   M*N rows and will contain as many columns as there are M-by-N
+%   neighborhoods in A. If the size of A is [MM NN], then the
+%   size of B is (M*N)-by-((MM-M+1)*(NN-N+1). Each column of B
+%   contains the neighborhoods of A reshaped as NHOOD(:), where
+%   NHOOD is a matrix containing an M-by-N neighborhood of
+%   A. IM2COL orders the columns of B so that they can be
+%   reshaped to form a matrix in the normal way. For example,
+%   suppose you use a function, such as SUM(B), that returns a
+%   scalar for each column of B. You can directly store the
+%   result in a matrix of size (MM-M+1)-by-(NN-N+1) using these
+%   calls:
+%
+%        B = im2col(A,[M N],'sliding');
+%        C = reshape(sum(B),MM-M+1,NN-N+1);
+%
+%   B = IM2COL(A,[M N]) uses the default block type of
+%   'sliding'.
+%
+%   B = IM2COL(A,'indexed',...) processes A as an indexed image,
+%   padding with zeros if the class of A is uint8 or uint16, or
+%   ones if the class of A is double.
+%
+%   Class Support
+%   -------------
+%   The input image A can be numeric or logical. The output matrix
+%   B is of the same class as the input image.
+%
+%   Example
+%   -------
+%   Calculate the local mean using a [2 2] neighborhood with zero padding.
+%
+%       A = reshape(linspace(0,1,16),[4 4])'
+%       B = im2col(A,[2 2])
+%       M = mean(B)
+%       newA = col2im(M,[1 1],[3 3])
+%
+%   See also BLOCKPROC, COL2IM, COLFILT, NLFILTER.
+
+%   Copyright 1993-2012 The MathWorks, Inc.
+
+[ma,na] = size(a);
+m = block(1); n = block(2);
+
+if any([ma na] < [m n]) % if neighborhood is larger than image
+    b = zeros(m*n,0);
+    return
+end
+
+% Create Hankel-like indexing sub matrix.
+mc = block(1); nc = ma-m+1; nn = na-n+1;
+cidx = (0:mc-1)'; ridx = 1:nc;
+t = cidx(:,ones(nc,1)) + ridx(ones(mc,1),:);    % Hankel Subscripts
+tt = zeros(mc*n,nc);
+rows = 1:mc;
+for i=0:n-1,
+    tt(i*mc+rows,:) = t+ma*i;
+end
+ttt = zeros(mc*n,nc*nn);
+cols = 1:nc;
+for j=0:nn-1,
+    ttt(:,j*nc+cols) = tt+ma*j;
+end
+
+% If a is a row vector, change it to a column vector. This change is
+% necessary when A is a row vector and [M N] = size(A).
+if ndims(a) == 2 && na > 1 && ma == 1
+    a = a(:);
+end
+b = a(ttt);
+