Hough Transform

Edges are among the earliest primitives that have been studied in computer vision. There are many other primitives that can be defined as Corner, line, circle, ellipse, square, triangle

The ultimate vision tasks involve the detection of general objects Face, pedestrian, vehicle, mouth, eyes, door

Two Paradigms

1. Model-based approaches : built a model

2. Data-driven (machine learning) approaches : here training set is provided to find objects for which complex models can't do it.

Generalizations of Hough Transform

 [H,theta,rho]=hough(f);

figure, imshow(theta,rho,H, [ ], 'notruesize')

axis on, axis normal;

xlabel('\theta'),ylabel('\rho'),

colorbar

colormap(jet)

[r,c]=houghpeaks(H,5);

hold on

plot(theta(c), rho(r), 'linestyle', 'none','marker' , ...

's', 'color', 'w')