How can I automatically identify multiple lines in an image? - image

Question

Given a binary image comprising angled lines, how could I automatically identify as much lines as possible? Using the bwtraceboundary function in Matlab, I have been able to identify one of them, manually providing the starting coordinates of the identified line.
Could anyone point out a way to loop the matrix of ones and zeros to automatically identify as many as possible?
Here's an example image:
% Read the image
I = imread('./synthetic.jpg');
figure(1)
BW = im2bw(I, 0.7);
imshow(BW2,[]);
c = 255; % X coordinate of a manually identified line
r = 490; % Y coordinate of a manually identified line
contour = bwtraceboundary(BW,[c r],'NE',8, 1000,'clockwise');
imshow(BW,[]);
hold on;
plot(contour(:,2),contour(:,1),'g','LineWidth',2);
From the above code we get:

Answer 1

This is a small example of how to use Hough transform for lines in MATLAB, with some denoising prior for your images.
This code does not detect all lines, and you may need to tune it/change it a bit, and that will need some learning on what is going on, which is out of the scope for StackOverflow. Perhaps someone with more knowledge can find a better method:
I=rgb2gray(imread('https://i.stack.imgur.com/fTWHh.jpg'));
I = imgaussfilt(I,1);
I=I([90:370],:);
BW = edge(I,'canny');
[H,T,R] = hough(BW);
P = houghpeaks(H,5,'threshold',ceil(0.3*max(H(:))));
lines = houghlines(BW,T,R,P,'FillGap',5,'MinLength',3);
figure, imshow(I), 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