/usr/share/octave/site/m/vlfeat/toolbox/imop/vl_imup.m is in octave-vlfeat 0.9.17+dfsg0-6build1.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 | function J = vl_imup(I)
% VL_IMUP Upsample an image by two
% J=VL_IMUP(I) doubles the resolution of the image I by using
% bilinear interpolation.
%
% See also: VL_IMDOWN(), VL_HELP().
% Copyright (C) 2007-12 Andrea Vedaldi and Brian Fulkerson.
% All rights reserved.
%
% This file is part of the VLFeat library and is made available under
% the terms of the BSD license (see the COPYING file).
[M,N,K] = size(I) ;
J = zeros(2*M,2*N,K) ;
J(1:2:end,1:2:end,:) = I ;
J(2:2:end,1:2:end,:) = 0.5*(I+[I(2:end,:,:);I(end,:,:)]) ;
J(1:2:end,2:2:end,:) = 0.5*(I+[I(:,2:end,:),I(:,end,:)]) ;
J(2:2:end,2:2:end,:) = ...
0.25*(...
J(2:2:end,1:2:end-1,:)+...
J(1:2:end-1,2:2:end,:)+...
[J(2:2:end,3:2:end,:),J(2:2:end,end-1,:)]+...
[J(3:2:end,2:2:end,:);J(end-1,2:2:end,:)]) ;
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