Whether you just unboxed a new phone or you are inspecting a used device before buying, a structured OLED test takes only a few minutes and can reveal hidden defects. This walkthrough shows you exactly what to check and in what order.
Step 1: Start with a black screen
The black screen test is the single most revealing check for OLED panels. Because OLED pixels turn off completely to show black, any pixel that glows faintly is either a stuck pixel or a sign of mura (panel unevenness).
Open the test in a dark room and look at the screen from multiple angles. A perfectly healthy OLED should be uniformly dark.
Step 2: Check for dead pixels with solid colors
Dead or stuck pixels are easiest to spot against pure primary colors. Cycle through:
- Red — reveals stuck green/blue subpixels
- Green — reveals stuck red/blue subpixels
- Blue — reveals stuck red/green subpixels
- White — reveals fully dead (black) pixels
Any dot that stays a different color from the background is worth noting. One or two isolated stuck pixels are common and usually acceptable; clusters or lines often indicate a more serious defect.
Step 3: Inspect uniformity with gray
A gray screen exposes banding, dirty screen effect (DSE), and tint shifts across the panel. Hold the screen at a normal viewing distance and look for vertical or horizontal bands, cloudy patches, or color gradients.
Some variation is normal on large panels, but obvious banding that is visible in real content (especially in streaming video) is a quality issue.
Step 4: Look for burn-in
Switch to white and then to a mid-gray background. If you can see faint outlines of static UI — a status bar, a logo, a navigation bar — that is image retention or burn-in.
To distinguish the two, display varied full-screen content for ten minutes and recheck. If the outline disappears, it was temporary retention. If it persists, it is likely permanent burn-in.
Step 5: Verify color accuracy
Finally, view the primary colors again and confirm they look saturated and clean, without halos or smearing. This is also a good moment to check the screen at different brightness levels, since some tint issues only appear at low or high brightness.
What to do if you find a defect
If the device is new and within the return window, even a single confirmed defect is usually grounds for exchange. For used devices, use your findings to negotiate price or walk away from the deal. The test results give you objective evidence rather than a gut feeling.