How to get a closed boundary of image recognition?

The boundaries of the graphics are identified. Now I need to get a closed boundary with a gray scale greater than 200, and the x, y coordinates of each boundary are known.

%plot code

    % code
clear all;
clear;
clc;
load('imagdata.mat');  
load('imgx.mat');         
load('imgy.mat');        
load('org_dataisld.mat');
imagesc(imgx,imgy,imagdata);  
colormap(flipud(gray));
colorbar('northoutside');
set(gca,'YDir','reverse')
caxis(gca,[0.5 256])
len = length(org_dataisld);
hold on;
for i = 1:len
   self_data = org_dataisld{i}(:,:);
   plot(imgx(self_data(:,1)),imgy(self_data(:,2)),'-g');
end
hold off

Answer 1

[Yongjun Wang]

Starting from the data body org_dataisld.mat

Answer 2

[Yongjun Wang]

The funciton bwboundaries can solve this problem.

Answer 3

[Yongjun Wang]

This problem has been solved which takes me a month.

[Image Analyst]

I could have done it in a few minutes if I had just understood what you wanted. I still don't, actually.

[Yongjun Wang]

Still want to thank you.