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Line detection in an image

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Chathu
Chathu on 28 Feb 2015
Commented: Chathu on 28 Feb 2015
My image is a square. What i want here is: select 4 points on the upper horizontal boundary in the square and along those 4 points draw a straight line. (eventually, repeat this for all 4 sides). What functions should i use?
When selecting points i can use ginput(4) i guess, but i doubt houghline is the function for drawing straight line along selected points? Any suggestions?

Accepted Answer

Image Analyst
Image Analyst on 28 Feb 2015
To plot the line in the overlay, you can use line()
line([x1 x2], [y1 y2], 'Color', 'r');
To "burn" the line into the image, you can either use normal indexing if the line is along rows and columns
grayImage(row1:row2, col) = 255; % or whatever intensity you want
or you can use imline() if the points are not in the same row or column, as the attached demo illustrates.
  3 Comments
Image Analyst
Image Analyst on 28 Feb 2015
I don't know what that last sentence means. Yes, there is an imregister() function, and related functions like imwarp(). Is that what you're looking for?
Chathu
Chathu on 28 Feb 2015
@ Image Analyst- sorry to confuse you. But thank you so much for your response. Really appreciate your effort.

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