What is the difference in these two methods of finding coordinates of image?
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I am trying to find coordinates of a line in my binary image. I used two methods.
1) X=imread('line.png'); [I,J] = find(X ==0); this methods give me multiple coordinates of the whole image.
2) A=imread('line.png'); image(A) [x,y]=ginput(); this methods give me the coordinates of the points on the line that I click by mouse.
Using method 2, I click multiple points (between start and end point of the line) and I get coordinates of those points. But when I compared the results getting from method 2 and method 1, they are different. I know that the cooridinate points may be different depending on my clicking. But I think the start and end coordinate (i.e. start and end of the line) should be the same?
Can anyone help me what the difference between these two methods? Are they finding different coordinate system?
David Young on 18 Jan 2016
The results of find are [row, column]. The results of ginput are [column, row].
That is, find uses the matrix convention for coordinate ordering, but ginput uses the image and graphics convention.
Does this explain the difference you observe?