Record normal conditions
Use your normal brightness and comfortable viewing distance. Note the room lighting and display mode. Open the black background in fullscreen and hide the controls. The browser cannot read your brightness setting or measure emitted light, so add these conditions yourself.
Change only your position
Observe the patch from your normal seat, then move slightly. Some LCD glow changes visibly with angle; a more fixed edge patch may have a different explanation. This is a descriptive comparison, not an automatic diagnosis. Reflections, local dimming and panel technology remain relevant.
Compare with ordinary content
Return to a dark scene or application you actually use at the same settings. An extreme brightness in a completely dark room may make a different practical impression than daily use. A grayscale gradient can help describe other visible transitions, but it is not a calibrated gamma or uniformity measurement.
Make evidence comparable
Phone auto-exposure can exaggerate faint light. If support requests photographs, follow its instructions and keep exposure and conditions consistent. Label reports with your own observations. An OLED panel has no LCD backlight; persistent brightness differences there require a different explanation. Never press the panel or loosen its chassis as a test.
Keep both reports in Device Lab →