i was given a an image with black lines on white background . what i need to do is, to find the coordinates of the edges at the intersection of black lines..can u plz suggest a way to start with....plzz

ls

Answer 1

[Image Analyst]

Threshold. If you want to find centroids of the crossing points, skeletonize with bwmorph(), then find crossing points with bwmorph().

If you have thick lines and want to find the "edges" of the intersection you need to define that. Do you mean just the 4 coordinates at the corners? Or do you mean the quadrilateral of all 4 straight edges where the two thick lines cross? How thick are these lines? Why do you want the edges instead of the center coordinate of where they cross?

You forgot to attach your image. Please do so.

[srinivas sri]

what i mean is the coordinates of points at which horizontal and vertical lines meet ...

[Image Analyst]

The attached file will get you 95% of the way there. I didn't do the last 5% because I think this may be a homework assignment and you need to do something on it.

Answer 2

[Matt J]

As a start, the following will separate the image into a binary image H of horizontal lines and V of vertical lines.

A=double(rgb2gray(imread('sid.png'))<10); 

   e=ones(1,7);

   H=conv2(A,e,'same')>3;
   V=conv2(A,e.','same')>3;

[srinivas sri]

that is fine thank u ..but i need function to find the coordinate values...

[Matt J]

Yes. I gave you the first step. Neither I, nor Image Analyst, nor anyone else here, I believe, will give you the whole thing. But... consider the FIND command.

[srinivas sri]

thank u very much..