extractneighbourhood.m

MATLAB Denoising software for grayscale images

function [Y,center] = extractNeighbourhood(band,block,parentband,parent)

% function [Y,center] = extractNeighbourhood(band,block,parentband,parent)
%
% Extracts all neighbourhoods of size 'block(1)'x'bock(2)' from the subband
% 'band'. If 'prnt'>0 the parent coefficient in band 'parentband' will be
% included in the neighbourhood as well. All possible (overlapping) patches
% of this size are stored in 'Y'. The index of the center coefficient in a
% neighbourhood willl be 'center'. Patches which will not have full size
% because of the border of the image won't be created.
%
% where
%   'band'      is the current subband
%   'block'     the size of the neighborhood (block sized) [D D]
%   'parentband' and 'parent' the same for the parental subband
%
%   'Y'         the extracted block neighborhoods
%   'center'    the index of the center coefficient
%
% Peter-Vincent Gehler 15.March 2005

% The number of coefficients ...
nCoeff = (size(band,1)-block(1)+1) * (size(band,2)-block(2)+1);

nblv = size(band,1)-block(1)+1;
nblh = size(band,2)-block(2)+1;

Ly = (block(1)-1)/2;
Lx = (block(2)-1)/2;

N = prod(block) + parent;
Y = zeros(nCoeff,N);

n=0;
for nx=Lx:-1:-Lx,
    for ny=Ly:-1:-Ly,	
        n = n + 1;
        Y(:,n) = vectorize(band(Ly+1-ny:Ly+nblv-ny,Lx+1-nx:Lx+nblh-nx));
    end
end

if parent    
    n = n + 1;
    Y(:,n) = vectorize(parentband(Ly+1:Ly+nblv,Lx+1:Lx+nblh));
end

center = (prod(block)+1)/2;