
From:  ariel.solomon 
Subject:  Help 
Date:  Thu, 1 Nov 2018 15:28:00 +0200 
Hi, I have copied and assimilated the houghpeaks function into octave. The function: function [r, c, hnew] = houghpeaks(h, numpeaks, threshold, nhood) %HOUGHPEAKS Detect peaks in Hough transform. % [R, C, HNEW] = HOUGHPEAKS(H, NUMPEAKS, THRESHOLD, NHOOD) detects % peaks in the Hough transform matrix H. NUMPEAKS specifies the % maximum number of peak locations to look for. Values of H below % THRESHOLD will not be considered to be peaks. NHOOD is a % twoelement vector specifying the size of the suppression % neighborhood. This is the neighborhood around each peak that is % set to zero after the peak is identified. The elements of NHOOD % must be positive, odd integers. R and C are the row and column % coordinates of the identified peaks. HNEW is the Hough transform % with peak neighborhood suppressed. % % If NHOOD is omitted, it defaults to the smallest odd values >= % size(H)/50. If THRESHOLD is omitted, it defaults to % 0.5*max(H(:)). If NUMPEAKS is omitted, it defaults to 1. % Copyright 20022004 R. C. Gonzalez, R. E. Woods, & S. L. Eddins % Digital Image Processing Using MATLAB, PrenticeHall, 2004 % $Revision: 1.5 $ $Date: 2003/11/21 13:34:50 $ if nargin < 4 nhood = size(h)/50; % Make sure the neighborhood size is odd. nhood = max(2*ceil(nhood/2) + 1, 1); end if nargin < 3 threshold = 0.5 * max(h(:)); end if nargin < 2 numpeaks = 1; end done = false; hnew = h; r = []; c = []; while ~done [p, q] = find(hnew == max(hnew(:))); p = p(1); q = q(1); if hnew(p, q) >= threshold r(end + 1) = p; c(end + 1) = q; % Suppress this maximum and its close neighbors. p1 = p  (nhood(1)  1)/2; p2 = p + (nhood(1)  1)/2; q1 = q  (nhood(2)  1)/2; q2 = q + (nhood(2)  1)/2; [pp, qq] = ndgrid(p1:p2,q1:q2); pp = pp(:); qq = qq(:); % Throw away neighbor coordinates that are out of bounds in % the rho direction. badrho = find((pp < 1)  (pp > size(h, 1))); pp(badrho) = []; qq(badrho) = []; % For coordinates that are out of bounds in the theta % direction, we want to consider that H is antisymmetric % along the rho axis for theta = +/ 90 degrees. theta_too_low = find(qq < 1); qq(theta_too_low) = size(h, 2) + qq(theta_too_low); pp(theta_too_low) = size(h, 1)  pp(theta_too_low) + 1; theta_too_high = find(qq > size(h, 2)); qq(theta_too_high) = qq(theta_too_high)  size(h, 2); pp(theta_too_high) = size(h, 1)  pp(theta_too_high) + 1; % Convert to linear indices to zero out all the values. hnew(sub2ind(size(hnew), pp, qq)) = 0; done = length(r) == numpeaks; else done = true; end end I get an error each time with different nhood values: Input: P=houghpeaks(H,5,'threshhold',ceil(0.3*max(H(:)))); Error: P=houghpeaks(H,5,'threshhold',ceil(0.3*max(H(:)))); error: nhood(2): out of bound 1 error: called from houghpeaks at line 44 column 10 Any thoughts? Best, Ariel 
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