The test image, reached from the Output Settings in DISE Replay or DISE Composer is a good and effective way of configuring your display to achieve the best image quality.
The F1 key controls the scrolling ticker. Pressing it repeatedly will increase its speed or turn it off. This is useful to make sure that the frame rate is satisfactory - the ticker scrolls smoothly from right to left.
Read more: Stuttering_playback
The F2 key controls a moving, transparent image. Pressing it repeatedly will increase its speed or turn it off.
The F3 key controls what background is shown. The various backgrounds aid you in
If possible, use auto adjust or similar function on your display to make sure that the display will show the image in as good quality as possible.
Note: The test image is also a good way of pinning down display issues, as it is being rendered in a different way then normal playback.
To exit the test image, press the Escape key on your keyboard or right-click the window.