finding index inside a region

Question

Mohammad Golam Kibria 2011-7-26

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/12396-finding-index-inside-a-region

评论： Image Analyst 2021-4-23

suppose I have a matrix I.

I =

   4     4     4     4     4     4
   1     1     1     1     3     0
   1     3     3     1     3     0
   1     3     3     1     3     0
   1     1     1     1     3     0
   4     4     4     4     4     4

idx is the index of 1's in the matrix including all 3's inside 1;

I need to find the index of those 3s those are inside 1s.

I tried with the following code.Perhaps this is not the correct one.

idx1=find(I(idx)==3);

How can I get that? can any body help?

Thanks

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

Image Analyst 2011-7-26

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/12396-finding-index-inside-a-region#answer_16974

This will work to get ONLY the 3's inside, not any old number.

 binaryImage = I==1
 filledImage = imfill(binaryImage, 'holes')
 maskedImage = I .* filledImage
 justThe3s = ismember(maskedImage, 3)
 [rows cols] = find(justThe3s)

You could use either the logical indexes "justThe3s" or the rows and cols variables, whichever you mean by "indexes."

5 个评论
显示 3更早的评论隐藏 3更早的评论

Nick Ward 2021-4-23

Thanks for the reply.

I think this is what I'm looking for although I get these errors. Any ideas?

Image Analyst 2021-4-23

@Nick Ward, attach your image/matrix, and m-file in a new question after reading this:

TUTORIAL: How to ask a question (on Answers) and get a fast answer

请先登录，再进行评论。

Answer 2

Andrei Bobrov 2011-7-26

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/12396-finding-index-inside-a-region#answer_16971

BW = I==1;
[~,L] = bwboundaries(BW);
idx = find(L==2)

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

Image Analyst 2011-7-26

This will get any collection of numbers inside a contiguous perimeter of 1's, not just the 3's. For example it would also find 4's, 42's, and 18's - whatever happened to be inside. Mohammad, see my answer if you want something that is more "tunable" to just one single number, if that is what you want.

请先登录，再进行评论。