How to apply two polygon on two outlines

I have two images. The objective is to find the area of the approximation made by polygons in the contours of the images.

In the first image i drew a polygon and it gave me a satisfactory approximation of the contour (bellow) and thus I was able to obtain its area through the 'polyarea' function.

I would like to apply the same to the second image, where there are two outlines. I would like to obtain the area of the approximation made by two polygons in these two contours.

How could I change my code to achieve this effect?

Thanks in advance.

clc
clear 
close all
skip = 320;

load('Image.mat');
image = preenc;

% Identify  the contours and its areas
Contours = bwconncomp(preenc, 8);
area = regionprops(Contours, 'Area');
figure, imshow(preenc);

% Speeds up the use of boundary later
Bperimeter = bwperim(preenc);
Bperimeter = imdilate(Bperimeter,strel('square',4));

% Get x,y coordinates of perimeter (column index and row index,
% respectively)
[y,x] = find(Bperimeter);
k = boundary(x,y,1); %use boundary with shrink factor of 1 to find vertices

% Back to the initial binary image, add the polygon using recently
% obtained vertices
idx = [k(1:skip:end);k(1)];
drawpolygon('Position',[x(idx) y(idx)])

% Calculate the area of the polygon
d = polyarea(x(idx),y(idx));
disp(d)

[Rena Berman]

(Answers Dev) Restored edit

Answer 1

[Ameer Hamza]

Try this

clc
clear
close all
skip = 50;

load('image2.mat');
image = preenc;

% Identify  the contours and its areas
Contours = bwconncomp(preenc, 8);
area = regionprops(Contours, 'Area');
figure, imshow(preenc);

for i=1:Contours.NumObjects
    image_ = image;
    % hide all other patches
    mask = zeros(size(image));
    mask(Contours.PixelIdxList{i}) = 1;
    image_(~mask) = 0;
    
    % Speeds up the use of boundary later
    Bperimeter = bwperim(image_);
    Bperimeter = imdilate(Bperimeter,strel('square',4));

    % Get x,y coordinates of perimeter (column index and row index,
    % respectively)
    [y,x] = find(Bperimeter);
    k = boundary(x,y,1); %use boundary with shrink factor of 1 to find vertices

    % Back to the initial binary image, add the polygon using recently
    % obtained vertices
    idx = [k(1:skip:end);k(1)];
    drawpolygon('Position',[x(idx) y(idx)])

    % Calculate the area of the polygon
    d = polyarea(x(idx),y(idx));
    disp(d)
end

[Image Analyst]

image is a built-in function so you shouldn't use image as the name of a variable.

Also, see these links, some of which might be interesting:

https://www.mathworks.com/matlabcentral/answers/304710-how-to-decrease-the-number-of-points-in-a-shape

https://en.wikipedia.org/wiki/Minimum_bounding_box_algorithms

https://www.mathworks.com/matlabcentral/answers/498605-hello-i-have-a-problem-with-a-while-condition-can-you-please-help-me

Google search for minimum perimeter polygon

and see attached article.

[Ameer Hamza]

Mark, thanks for pointing to useful information.