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% RES = upConv(IM, FILT, EDGES, STEP, START, STOP, RES)
%
% Upsample matrix IM, followed by convolution with matrix FILT. These
% arguments should be 1D or 2D matrices, and IM must be larger (in
% both dimensions) than FILT. The origin of filt
% is assumed to be floor(size(filt)/2)+1.
%
% EDGES is a string determining boundary handling:
% 'circular' - Circular convolution
% 'reflect1' - Reflect about the edge pixels
% 'reflect2' - Reflect, doubling the edge pixels
% 'repeat' - Repeat the edge pixels
% 'zero' - Assume values of zero outside image boundary
% 'extend' - Reflect and invert
% 'dont-compute' - Zero output when filter overhangs OUTPUT boundaries
%
% Upsampling factors are determined by STEP (optional, default=[1 1]),
% a 2-vector [y,x].
%
% The window over which the convolution occurs is specfied by START
% (optional, default=[1,1], and STOP (optional, default =
% step .* (size(IM) + floor((start-1)./step))).
%
% RES is an optional result matrix. The convolution result will be
% destructively added into this matrix. If this argument is passed, the
% result matrix will not be returned. DO NOT USE THIS ARGUMENT IF
% YOU DO NOT UNDERSTAND WHAT THIS MEANS!!
%
% NOTE: this operation corresponds to multiplication of a signal
% vector by a matrix whose columns contain copies of the time-reversed
% (or space-reversed) FILT shifted by multiples of STEP. See corrDn.m
% for the operation corresponding to the transpose of this matrix.
% Eero Simoncelli, 6/96. revised 2/97.
function result = upConv(im,filt,edges,step,start,stop,res)
%% THIS CODE IS NOT ACTUALLY USED! (MEX FILE IS CALLED INSTEAD)
fprintf(1,'WARNING: You should compile the MEX version of "upConv.c",\n found in the MEX subdirectory of matlabPyrTools, and put it in your matlab path. It is MUCH faster, and provides more boundary-handling options.\n');
%------------------------------------------------------------
%% OPTIONAL ARGS:
if (exist('edges') == 1)
if (strcmp(edges,'reflect1') ~= 1)
warning('Using REFLECT1 edge-handling (use MEX code for other options).');
end
end
if (exist('step') ~= 1)
step = [1,1];
end
if (exist('start') ~= 1)
start = [1,1];
end
% A multiple of step
if (exist('stop') ~= 1)
stop = step .* (floor((start-ones(size(start)))./step)+size(im))
end
if ( ceil((stop(1)+1-start(1)) / step(1)) ~= size(im,1) )
error('Bad Y result dimension');
end
if ( ceil((stop(2)+1-start(2)) / step(2)) ~= size(im,2) )
error('Bad X result dimension');
end
if (exist('res') ~= 1)
res = zeros(stop-start+1);
end
%------------------------------------------------------------
tmp = zeros(size(res));
tmp(start(1):step(1):stop(1),start(2):step(2):stop(2)) = im;
result = rconv2(tmp,filt) + res;
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