If you're removing the colour overlay, bear in mind the text may be less legible on certain images, perhaps consider replacing the green overlay with a very light semi-transparent black one.
Removing the colour overlay on clickable images but keeping the text
SOLVE
Thanks @Kevin-C - it almost worked! The green overlay has been removed, but I can't see the text and the Download button without the mouse pointing to the image. I know I'm overlooking something simple.