Here you go:
im=imread('https://www.mathworks.com/matlabcentral/answers/uploaded_files/119871/test1.png'); % grayscale
bw=imread('https://www.mathworks.com/matlabcentral/answers/uploaded_files/119872/test2.png'); % binary
B=bwboundaries(bw); % shape contours
% Superimpose contours on grayscale image
figure('color','w')
imshow(im)
hold on
for i=1:numel(B)
h=fill(B{i}(:,2),B{i}(:,1),'r');
set(h,'FaceAlpha',0.6,'EdgeColor','r','LineWidth',2)
end
