orzHOG.m

function [D] = orzHOG(X,orBin,nCellSize,nBlockSize)
%orzHOG(X,orBin)

% X = imread('Z:\Documents\Manuscripts\2008\CSƒZƒ~ƒi[\2009\Fig\FACE.bmp');
% X = imresize(X, 128/120);
% X=X(:,1:2:end);
% X = double(X)/255;
% X = imread('C:\Users\PuriPuri-S10\Desktop\DC-ped-dataset_base\1\non-ped_examples\img_00000.pgm');
% X = double(X)/255;

nEps = 1e-5;
%nCellSize = 5;
%nBlockSize = 3;
nSH = ceil(size(X,1)/nCellSize);
nSW = ceil(size(X,2)/nCellSize);
nHH = nSH-nBlockSize+1;
nWW = nSW-nBlockSize+1;
G = zeros([size(X),2]);



% Roberts Filter
H = [-1,0,1];
G(:,:,1) = imfilter(X,H,'replicate');
G(:,:,2) = imfilter(X,-H','replicate');

% N: gradient magunititude
N = sqrt(sum(G.^2,3));
% A: gradiennt orientation
A=atan2(G(:,:,2),G(:,:,1))+pi;
A(A > pi) = A(A > pi)-pi;

F = zeros([size(X),orBin]);
BB= linspace(0,pi,orBin+1);
BB = BB(1:orBin) + pi/(2*orBin);
for B=1:orBin
    F(:,:,B) = (abs(A-BB(B)) <= pi/(2*orBin)).*N;
end
AAA=orzSubRegion(F,nSH,nSW);
D = zeros(orBin*nBlockSize^2,nHH,nWW);
for I=1:nHH
    for J=1:nWW
        V = AAA(:,I:I+nBlockSize-1,J:J+nBlockSize-1);
        D(:,I,J) = V(:)/norm(V(:)+nEps);
    end
end
D=D(:);