Overlaying manipulated RBG with grayscale image

Hello all!

I have an all red image ("red") that I combined with a binary mask ("mask"), such that only the pixels that are true in the binary mask is shown. I need the transparent red to be displayed as an overlay with a grayscale background image ("background"). Essentially, I want the transparent red to highlight parts of my grayscale image. I built a transparent red image corresponding to the binary mask with the following:

red=zeros(512,512,3);
red(:,:,1)=1;
hold on
h = imshow(red);
hold off
set(h, 'AlphaData', mask.*0.3)

I cannot figure out how to overlay this image with my background grayscale image however... The two keep showing as separate figures. Thank you so much!

Answer 1

[Image Analyst]

See if either of these two instructional demos help:

http://blogs.mathworks.com/steve/2009/02/18/image-overlay-using-transparency/

http://www.mathworks.com/matlabcentral/answers/104889-how-to-overlay-a-foreground-image-over-a-background-image

[Brian]

The first link is exactly what I needed! Turns out I just have my plotting command in the wrong line. Thank you so much!