A Computational Introduction to Digital Image Processing, 2nd Edition

Image Segmentation 253

MATLAB/Octave

>> s = im2double(imread(’stairs.png’));

>> [r,c] = size(s);

>> dirs = [1 1;1 0;-1 0;0 1;0 -1;-1 -1;1 -1;-1 1];

>> sp = padarray(s,[1,1]);

>> z = zeros(r+2,c+2,8);

>> w = zeros(r+2,c+2,8);

>> for i = 1:8

> z(2+dirs(i,1):1+dirs(i,1)+r,2+dirs(i,2):1+dirs(i,2)+c,:) = s;

> w(:,:,i) = imfilter((z(:,:,i)-sp).^2,ones(3,3));

> end

>> corners = min(w,3);

To show the corners, create an image that includes a darkened version of the original added

to a brightened version of the corners array:

MATLAB/Octave

>> imshow(s/4+4

*

corners(2:r+1,2:c+1))

and the result is shown in Figure 9.33.

FIGURE 9.33: Moravec corner detection

Python has a

corner ...