Lost shadow detail can come from the source, room reflections, an incorrect signal range or unsuitable picture controls. First compare another known source and inspect the active mode. Raising black level indiscriminately may reveal noise and turn blacks grey without correcting the underlying interpretation.
Use a scene with real texture
Choose dark fabric, hair or a dim room where detail should be visible, rather than an intentionally black fade. Compare the same scene under controlled lighting. A bright lamp reflected in the screen can hide subtle differences even when the display is receiving and rendering them correctly.
Check signal matching first
An RGB range mismatch can clip near-black information. Verify supported automatic or matching settings across the source and display before making cosmetic adjustments. Televisions use different names for black level and panel light output, so consult the model’s explanation instead of treating every brightness-labelled slider as equivalent.
Keep the adjustment balanced
After a change, inspect bright detail and normal faces as well as shadows. A setting that uncovers everything in one dark scene may flatten the rest of the picture. If only one programme is affected, note the title and time rather than applying a global correction that compromises all other viewing.