I would like to mask a color image with an interactive transparent rectangle over an identical black and white image. The idea is to allow a user to move the rectangle to make different areas of the image color.
I cannot find a property that would bind the specific area of the rectangle to the opacity of the color image. What I was able to do, though, was to create a group with the rectangle and the color image. Unfortunately, when I move the group in preview, the color image remains static within it.