Fig. 3
From: Line and circle detection using dense one-to-one Hough transforms on greyscale images
Voting in one-to-one DHT (the estimation scale used here is σ=3.0; for visibility purposes, at most, one vote per 5×5 block is displayed). a Voting weight at order 1: the magnitude of the gradient. b Votes for the gradient direction (only votes with weights higher than 2.5 are displayed). c Voting weight at order 2: the Frobenius norm of the Hessian matrix. d Votes for the position of the centre of osculating circle (only votes with weights higher than 0.5 are displayed)