How to Test OLED Uniformity & 5% Gray Banding
Master the industry-standard 5% gray benchmark for inspecting vertical jailbars and near-black tinting.
1. Why 5% Gray is the Gold Standard
Driving self-emissive OLED pixels at 100% black is easy: the subpixels are completely powered down. Driving them at 100% white is equally straightforward: full voltage is applied.
The true challenge for OLED panel driving circuits is low-luminance analog voltage precision (digital levels 1 to 16, representing 1% to 5% stimulus). Microscopic variations in transistor threshold voltage across the substrate cause adjacent columns to illuminate slightly brighter or darker, producing vertical streaks known as "jailbars".
2. Proper Testing Environment
• Completely darken the room. Even minor ambient reflections will wash out 5% gray visibility.
• Allow your eyes 2 minutes to adapt to the dark.
• Open the ScreenCheck OLED Uniformity Test and select 5% Gray.
• Inspect for severe thick bands down the center of the display.
• Compare with 10% and 20% gray. If banding vanishes completely above 10% gray, it will rarely intrude on normal gaming or video content.
New OLED panels straight out of the box frequently exhibit mild vertical banding that noticeably smooths out after the panel performs its first 2 to 3 automated 4-hour compensation cycles.
Recommended Interactive Tests
Run these dedicated fullscreen tools to test your display against this guide's criteria:
Frequently Asked Questions
Is some vertical banding on 5% gray normal?
Yes, almost every large-format OLED panel has faint vertical striations visible on a 5% gray slide in a pitch-black room. As long as they are not visible in real movies or games, it is well within manufacturing tolerance.
Related Diagnostic Guides
Continue learning with complementary display inspection guides:
OLED Burn-In vs. Temporary Image Retention
Understand how OLED self-emissive subpixels wear down over time, why temporary image retention disappears after a compensation cycle, and how to protect your OLED.
What is Mini-LED Blooming & How Local Dimming Works
Learn why bright objects against dark backgrounds cause halos on Mini-LED displays, how zone counts impact blooming, and how to test for local dimming artifacts.