How to overlay a binary mask over an rgb image?

I am trying to overlay a binary mask over an RGB color image. I want to change the white area of the mask to a transparent red area and put it over an rgb image.

For example:

image: mask:

I want something similar to this:

I alredy tried this method but I couldn't figure it out. What is a simple way (no matter how slow) to do this?

[Turlough Hughes]

What size is your mask and original image?

Answer 1

[Meg Noah]

Here's some code:

img = imread('diplo000000-L.png');
mask = imread('sdfsd.png');
mask(:,:,1) = 0;
img(mask>0) = 0;
image(img)
set(gca,'ydir','reverse');
imwrite(img,'newimage.png');

[Andrew Soltisz]

img(mask>0) = 0; is equivalent to img(mask) = 0;

[Hadi Ghahremannezhad]

Thank you. That's a good point.