Check where the picture changes
Open the television menu over the affected item, then check the input or playback information. A bright menu and a dark picture do not identify the source of the problem by themselves. Some TVs save different picture modes for SDR, HDR or separate inputs. The app, box and display can also disagree about a format. A short controlled comparison tells you which change matters.
Try two clips in the same setup
Play one SDR and one HDR item you are authorized to use on the same player and input. Note the output or HDR signal and whether each looks as expected. If you are using Apple TV, check the Match Content options described in the Apple guide. Try one setting at a time, keep the original value in your notes and check the same item again.
| Observation | Compare next |
|---|---|
| Only one HDR programme looks wrong | Try another known HDR item on the same app. |
| Every HDR programme is unusually dark on one input | Check that input’s picture mode and the display’s reported format. |
| Video briefly disappears when HDR starts | Check the format change and HDMI path. |
| All output looks dim including the TV’s own apps | Use the television’s support route to check its picture settings. |
Keep a working baseline
Write down the app, TV model, active input and changed setting. If the issue also happens with the TV’s built-in app, include that result. A useful report describes one consistent programme and one control instead of changing several global picture controls between runs.