Home How to label separate lines in the image (image of a text) separately using "bwlabel" in matlab?
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How to label separate lines in the image (image of a text) separately using "bwlabel" in matlab?

amIllusionist
1#
amIllusionist Published in 2017-12-07 14:19:24Z

I have recognized and labeled objects in my image that is fully consists of texts. you can see the objects are labeled as red color in the attached image. so, I want to separate the objects in the second line (or more lines) from the first line and give them different colors (each line would has a different colors) but I can't do that. do you have any idea? thanks for all answers. this is part of my matlab code that does the labeling:

%% Label connected components
[L, Ne]=bwlabel(imagen);
%% Measure properties of image regions
propied=regionprops(L,'BoundingBox');
hold on
%% Plot Bounding Box
for n=1:size(propied,1)
    rectangle('Position',propied(n).BoundingBox,'EdgeColor','r','LineWidth',2)
end

and this is labeled image that all the objects in different lines have the same label (same color=red).

dhanushka
2#
dhanushka Reply to 2017-12-09 03:24:45Z

I think the following methods should work if the lines are not too curvy.

  • Find the centroids of the bounding boxes, or get the centroids from the regionprops itself, then cluster their y coordinates using kmeans with k = 2. The result is not perfect, but fine. May be you can then fit a curve to the clustered points, with outlier removal (e.g. RANSAC)

OR

  • Prepare a new image by filling in the bounding boxes.

  • Prepare a rectangular structuring element whose height is 1 and width is the width of the widest bounding box.

  • Perform a morphological closing of the filled image using this structuring element. This will connect the regions horizontally. Now you get a mask separating the two regions.

The resulting images were obtained using opencv (I'm not posting the code because it's too untidy. Hope the instructions are clear enough).

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