MATLAB: How to count number of vertical and horizontal lines in an image using matlab

horizontal linehoughimage processingImage Processing Toolboxvertical line

Hi guys

How do you use hough transform to count number of vertical and horizontal lines that are detected in an image?

Marcus

Best Answer

You detect them and count them. What example from the help are you running?

Related Solutions

MATLAB: How to measure the angle of a line in the image using the Image Processing Toolbox in MATLAB

To recognize line objects in your figure window, you may use the HOUGH Transform. Information about the HOUGH transform may be found at the following location:

 <http://www.mathworks.com/help/toolbox/images/ref/hough.html>

As a simple example, run the following code on the attached file "test.jpg":

% read the image into MATLAB and convert it to grayscale
I = imread('test.jpg');
Igray = rgb2gray(I);
figure, imshow(I);
% We can see that the image is noisy. We will clean it up with a few
% morphological operations
Ibw = im2bw(Igray,graythresh(Igray)); 
se = strel('line',3,90);
cleanI = imdilate(~Ibw,se);
figure, imshow(cleanI);
% Perform a Hough Transform on the image 
% The Hough Transform identifies lines in an image 
[H,theta,rho] = hough(cleanI);
peaks  = houghpeaks(H,10);
lines = houghlines(Ibw,theta,rho,peaks);
figure, imshow(cleanI)
% Highlight (by changing color) the lines found by MATLAB
hold on
for k = 1:numel(lines)
    x1 = lines(k).point1(1);
    y1 = lines(k).point1(2);
    x2 = lines(k).point2(1);
    y2 = lines(k).point2(2);
    plot([x1 x2],[y1 y2],'Color','g','LineWidth', 2)
end
hold off
% Identify the angles of the lines. 
% The following command shows the angle of the 2nd line found by the Hough
% Transform
lines(1).theta
lines(2).theta

MATLAB: How to get a line information after applying the houghlines

In your example, the variable lines has the information about the straight lines. Double-click the variable in the Workspace. You will see that it has the coordinates of the end points of the lines ( point1 and point2 ). Also, theta gives you the angle information. 90 - theta is the actual angle of the lines, measured counter-clockwise from +x axis.

Best Answer

Related Solutions

MATLAB: How to measure the angle of a line in the image using the Image Processing Toolbox in MATLAB

MATLAB: How to get a line information after applying the houghlines

Related Question