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# Thread Subject: edge detection with coordinates of edge points

 Subject: edge detection with coordinates of edge points From: Toan Cao Date: 16 Oct, 2010 02:54:04 Message: 1 of 5 hi, everybody! I have a gray image with the horizontal and vertical lines, i would like to detect the edge of these lines. Moreover, i also want to know the coordinate of each point on each edge after edge detection process complete! Is there any function or method to accomplish my purpose ? Looking forward to your reply . Thank you very much !
 Subject: edge detection with coordinates of edge points Date: 22 Oct, 2010 17:18:04 Message: 2 of 5 i also searching for same question..if u got any code reply me...tq...u cn try this code i got from matlab tutor... % Demo macro to find books % NOT FINISHED..... % by ImageAnalyst clc; clear; close all; workspace; fontSize = 20; % Change the current folder to the folder of this m-file. if(~isdeployed) cd(fileparts(which(mfilename))); end % Read in books image. folder = 'C:\Documents and Settings\user\My Documents\downloads'; baseFileName = 'books.jpg'; fullFileName = fullfile(folder, baseFileName); rgbImage = imread(fullFileName); % Display the original color image. subplot(2, 2, 1); imshow(rgbImage); title('Original Color Image', 'FontSize', fontSize); set(gcf, 'Position', get(0,'Screensize')); % Enlarge figure to full screen. set(gcf,'name','Demo by ImageAnalyst','numbertitle','off') grayImage = rgb2gray(rgbImage); % Do a Canny edge detection on the image. BW = edge(grayImage,'canny'); subplot(2, 2, 2); imshow(BW, []); title('Edge Image', 'FontSize', fontSize); [H,T,R] = hough(BW); subplot(2, 2, 3); imshow(H,[],'XData',T,'YData',R,...             'InitialMagnification','fit'); title('Hough Image', 'FontSize', fontSize); xlabel('\theta'), ylabel('\rho'); axis on, axis normal, hold on; P = houghpeaks(H,10,'threshold',ceil(0.3*max(H(:)))); x = T(P(:,2)); y = R(P(:,1)); plot(x,y,'s','color','white'); % Find lines and plot them lines = houghlines(BW,T,R,P,'FillGap',25,'MinLength',7); % Put code in here to toss out horizontal lines. % Display original image with lines over it. subplot(2, 2, 4); imshow(rgbImage); title('Original Color Image with Lines', 'FontSize', fontSize); hold on; max_len = 0; for k = 1:length(lines)    xy = [lines(k).point1; lines(k).point2];    plot(xy(:,1),xy(:,2),'LineWidth',2,'Color','green');    % Plot beginnings and ends of lines    plot(xy(1,1),xy(1,2),'x','LineWidth',2,'Color','yellow');    plot(xy(2,1),xy(2,2),'x','LineWidth',2,'Color','red');    % Determine the endpoints of the longest line segment    len = norm(lines(k).point1 - lines(k).point2);    if ( len > max_len)       max_len = len;       xy_long = xy;    end end
 Subject: edge detection with coordinates of edge points From: Sean Date: 22 Oct, 2010 17:32:06 Message: 3 of 5 "Toan Cao" wrote in message ... > hi, everybody! > I have a gray image with the horizontal and vertical lines, i would like to detect the edge of these lines. Moreover, i also want to know the coordinate of each point on each edge after edge detection process complete! > Is there any function or method to accomplish my purpose ? > Looking forward to your reply . > Thank you very much ! help edge help bwperim %if you can convert to binary
 Subject: edge detection with coordinates of edge points From: Pauline Addis Date: 1 Nov, 2010 15:13:04 Message: 4 of 5 "Toan Cao" wrote in message ... > hi, everybody! > I have a gray image with the horizontal and vertical lines, i would like to detect the edge of these lines. Moreover, i also want to know the coordinate of each point on each edge after edge detection process complete! > Is there any function or method to accomplish my purpose ? > Looking forward to your reply . > Thank you very much ! Hi, I have just managed fairly good results by first of all using the Canny edge detection method, then using bwboundaries to report back the location of the co-ordinates. search Matlab help for bwboundaries. Hope that helps.
 Subject: edge detection with coordinates of edge points From: nguyen phuong Date: 19 Dec, 2011 04:12:08 Message: 5 of 5 hi