How do i count the horizontal lines in an image

I am new to MATLAB. How do i write a code which detects and counts horizontal lines in an image. Example is below. Any method of image analysis would be helpful. Thank you

[Akira Agata]

Is it possible to erase the red line mesh? Or do we have to use this image as an input?

[N/A]

Sorry i'll upload the original picture. I put the mesh on that one myself.

Answer 1

[Akira Agata]

Thank you for uploading the clean image!

In my view, one simple and straight-forward solution will be regionprops function. The following is one example to extract horizontal lines in the image.

% Read your image and binarize
I = imread('5159-15B front_imgJ-macro.jpg');
I = rgb2gray(I);
BW = imbinarize(I);

% Apply regionprops function
s = regionprops(~BW,{'MajorAxisLength','MinorAxisLength','BoundingBox','Orientation'});
s = struct2table(s);

% Extract the regions which satisfies both the following conditions:
% (1) (Minor axis length)/(Major axis length) <= 10%
% (2) Angle with horizontal line <= +- 5 degree
idx =...
  (s.MinorAxisLength ./ s.MajorAxisLength <= 0.1) &...
  (abs(s.Orientation) <= 5);
s = s(idx,:);

% Show the result
figure
imshow(I)
hold on
for kk = 1:height(s)
  rectangle(...
      'Position', s.BoundingBox(kk,:),...
      'EdgeColor','r')
end