After enabling the NVIDIA Image Scaling, you can make it appear as an overlay indicator in your games. This is similar to the FPS displayed in the games by FPS Counter software. This NIS overlay indicator will help you know whether NIS is working or not. If NIS is working, the overlay indicator (NIS text label displayed on the top left corner of the screen) will be green. If it is not working, the color of the indicator will be blue.