crop or save an overlaid image using transparency

I have created a figure of overlaid images using transparency from here. I am interested to get the exact matrix of the following image to use a part of the image.

I tried to save the image using "print" or "saveas" and crop that image. But, the saved image contains the white borders of the figure and does not save the image with true size. (I changed the border pixel intensities so that it can be seen here).

I tried to crop a part of image. I tried imcrop, but since there are 2 images, in getimage function in imcrop two handles are found.

I was wondering if anyone could help me to find a way to get the crop of the overlaid image. something like this:

and I don't want the size of the image change.

Thanks,