How to detect the corners of a square in a binary image

Question

Yannic Ellhotka 2018-11-15

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/430061-how-to-detect-the-corners-of-a-square-in-a-binary-image

回答： Image Analyst 2018-11-19

Hello,

I have a binary image of white square with slightly rounded corner on a black background. I need to get the coordinates of all 4 corners. I tried something like that:

[rows, columns] = find(BW);

topRow = min(rows)

bottomRow = max(rows)

leftColumn = min(columns)

rightColumn = max(columns)

This doesn’t always work because the square doesn’t always have right angles.

example iamge.

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Yash Ubale 2018-11-19

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/430061-how-to-detect-the-corners-of-a-square-in-a-binary-image#answer_347765

Hello,

Try using Hough transform to find lines in the image. After finding the lines, find the left-most, right-most, top-most and bottom-most lines. When you get these lines, just find their intersections to find the four corners of the square. Before doing so, I would suggest to erode the image with 'square' structuring element of width say 75, to remove the noise around the square.

Hough transform - https://www.mathworks.com/help/images/ref/hough.html

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

Answer 2

Image Analyst 2018-11-19

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/430061-how-to-detect-the-corners-of-a-square-in-a-binary-image#answer_347825

shape_recognition_demo1.m

See my attached shape recognition demo. It will show you how you can locate vertices by finding boundaries and plotting distances of the boundary points from the centroid and then looking for peaks.