Overlay strain map on scan (colored plot over black and white plot)

I am attempting to make a graphic for a presentation in which I would like to throw a strain map over a black and white image used for texture correlation. I currently have been unable to create separate colorbars, resulting in a colored scan or a black and white strain map. I've attached an image of what I'm moreorless trying to capture but can't seem to produce.

The code below takes a 400x200 uint8 (for the BW image), and a 400x200 double (for the strain map). The values outside of the strain map in the structure are labeled as NaN. Likewise, transparency is currently set to 1s and 0s accordingly. I haven't included any of my own data here for a reference image or for running the code for privacy reasons.

f3 = figure( 3 );

%Exx strain map

image( dataIMG( :, :, frame ) ); hold on;

imagesc( exx_plot, 'AlphaData', transparency );

colormap( 'jet' );

caxis( [0 0.15] );

colorbar;

Answer 1

[DGM]

Take the image you want to be grayscale and expand it to mxnx3 so that it isn't colormapped anymore:

https://www.mathworks.com/matlabcentral/answers/1659975-i-need-to-add-color-shapes-to-dose-distribution-images

https://www.mathworks.com/matlabcentral/answers/41039-jet-countour-plot-over-grayscale-image

For example,

% a grayscale image with some transparency
FG = imread('fg.png');
FGA = imread('fga.png');
opacity = 0.5;

% a grayscale image, but expanded
BG = imread('cameraman.tif');
BG = repmat(BG,[1 1 3]);

imshow(BG); hold on
hfg = imshow(FG);
hfg.AlphaData = FGA*opacity;
colormap(parula)

If you want both images to be colormapped independently, then you'll have to do it by overlaying two axes objects, since each axes can only have one colormap.

[Frederick Houghton]

Worked perfectly, thank you!

For anyone that may reference this post: FGA.png is simply a transparency matrix that labels the values to show on the plot and their opacity. For my purposes, I detected where my strain map fit onto the image and filled the borders with NaN values, and then set the strain map to 0.5 as suggested in this answer.