How to get the boundary points?

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Chathu 2016-5-2

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https://ww2.mathworks.cn/matlabcentral/answers/282060-how-to-get-the-boundary-points

评论： Chathu 2016-5-4

I have a mask(mask is for an image) which is saved in .mat format. Now, i want to take the boundary of this mask. Is it possible to convert from mask to boundary? Can anyone kindly guide me?

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Image Analyst 2016-5-2

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https://ww2.mathworks.cn/matlabcentral/answers/282060-how-to-get-the-boundary-points#answer_220346

Yes. Use bwboundaries() to get a list of (x,y) coorindates. Use bwperim() if you want an image of the outer boundary.

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Chathu 2016-5-2

编辑：Walter Roberson 2016-5-4

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Image Analyst, thank you sooo much for your response. Really admire your kindest support.

First, i apologize you if i confuse you. i would have been descriptive before.

Second,let me brief what i have so far. I have 3 masks.

1st mask (saved as .mat and .jpeg),

2nd mask (saved as .mat only),

3d mask (saved as .mat only).

From your 3rd response, i know that if i have RGB image how to find the boundaries.

But now when you look at the way 3 masks have been saved, the most generalize way would be to read back the .mat files, i guess

Kindly, note that when i type

storedStructure = load('P3290190.mat');

and type whos storedStructure following is what i obtained.

   Name                 Size              Bytes  Class     Attributes
   storedStructure      1x1             4407854   struct

Actually, i got stuck with the command 'binaryImage'.

mask = storedStructure.binaryImage;

What exactly should i say for binaryImage (binaryImage of the mask? or original image?)

Third, thank you so much for your effort. You have been a great help so far even.

Image Analyst 2016-5-4

Well you just have to figure out what the variable names were when they were saved, and then get back those same names, and make sure you're using the right one in the right place. It's just bookkeeping really. I mean, if the name is maskedRgbImage, it's probably an RGB image and don't use it where a gray scale image or binary (logical) image is expected.

Chathu 2016-5-4