Another experiment. Two identical images. Completely desaturated the green in one. Blurred the other. Layered the blurred colour image behind the desaturated one and set the top image to 45% opacity. Theoretically our brains fit wobbly colour to crisp edges (according to watercolour lessons I had years ago) and this is my finding the point where it starts to not.
Extra one. Double exposure with intentional camera movement on one of them:
