iharris.m

这是一个基于MATLAB的机器视觉工具箱,里面用很多非常有价值的的程序

%IHARRIS		Harris corner detector
%
%	C = IHARRIS(I)
%
%	Return an image of 'cornerness', C, from the original grey level image
%
% REF:	"A combined corner and edge detector", C.G. Harris and M.J. Stephens
%	Proc. Fourth Alvey Vision Conf., Manchester, pp 147-151, 1988.
%
% SEE ALSO:	showcorners
%
%	Copyright (c) Peter Corke, 1999  Machine Vision Toolbox for Matlab


%	pic 10/96

function cp = iharris(im)
	mask = [-1 0 1; -1 0 1; -1 0 1] / 3;

	% compute horizontal and vertical gradients
	Ix = conv2(im, mask, 'valid');
	Iy = conv2(im, mask', 'valid');
	
	% compute squares amd product
	Ixy = Ix .* Iy;
	Ix = Ix.^2;
	Iy = Iy.^2;

	% smooth them
	gmask = igauss(1, 1);

	Ix = conv2(Ix, gmask, 'valid');
	Iy = conv2(Iy, gmask, 'valid');
	Ixy = conv2(Ixy, gmask, 'valid');

	% computer cornerness
	c = (Ix + Iy) ./ (Ix .* Iy - Ixy.^2);

	% compute minimum value around each pixel
	cmin = imorph(c, ones(3,3), 'min');

	% if pixel equals minimum, its a local minima, find index
	l = find(c == cmin);

	cp = ones(size(c)) * max(max(c));
	cp(l) = c(l);