Images merging using matlab

I have this two images and I want to merge them in order to receive somthing like the third image can someone help me?

[Walter Roberson]

User removed files that were necessary to understand the question.

Fortunately, you can use the filenames from my post to get two of them back... at least for now.

[Inês]

I don't now what happened but I attached the photos again sorry if I caused any trouble.

[Rena Berman]

(Answers Dev) Restored edit

Answer 1

[Walter Roberson]

orig_filename = 'https://www.mathworks.com/matlabcentral/answers/uploaded_files/858715/CXR00000001.png';
roi_filename = 'https://www.mathworks.com/matlabcentral/answers/uploaded_files/858730/CXR00000001_lungs.png';

orig_image = imread(orig_filename);

roi_image = imread(roi_filename);
if ndims(roi_image) > 2; roi_image = rgb2gray(roi_image); end
roi = imbinarize(roi_image);
roi = repmat(roi, 1, 1, size(orig_image,3));

masked_image = zeros(size(orig_image), 'like', orig_image);
masked_image(roi) = orig_image(roi);

imshow(masked_image)