Customer question: Which test images should I use when inspecting a used LED screen?
English explanation
Use a repeatable test sequence rather than a single video. Display full white to reveal bright/dark pixels and overall uniformity. Display black to reveal unwanted light. Use red, green and blue fields to identify channel defects. Use gray steps and gradients to inspect low-gray behaviour, banding and uneven transitions. Add a grid, text and moving content to check mapping, sharpness and motion. Inspect the full wall from the normal viewing distance, then inspect individual cabinets from a closer but safe position. Record cabinet numbers and photograph every abnormal area. A defect that follows a cabinet boundary suggests a cabinet, receiver, power or signal issue. A defect that moves with a module may point to the module or its local connection. A colour difference that appears only through a camera may be related to shutter, refresh or moiré rather than a visible LED fault. For a used screen, test both cold start and stable operation. Some defects appear only after heat builds up. Keep brightness, content and camera settings constant so that before/after comparisons remain useful. If the seller changes configuration during the test, record the change and repeat the baseline pattern. Do not accept vague statements such as “a few pixels are normal” without agreeing on the applicable contract or acceptance standard.
Service boundary
Quality limits depend on the product, contract and viewing condition. The inspection report should separate visible defects, camera-only effects and items requiring further testing. —
