How to Use the Uniformity Test
1. Prepare the Room
Turn off all lights and close the curtains. Uniformity issues like backlight bleed are most visible in a dark environment.
2. Select Test Color
Start with Gray to check for clouding and dirty screen effect. Use Black (0% brightness) to check for backlight bleed.
3. Inspect the Screen
Look for uneven brightness patches, dark corners (vignetting), or light leaking from the edges. The screen should look perfectly uniform.
Why Uniformity Matters
For Photographers
Uniformity is critical for editing. If your screen has vignetting (dark corners), you might over-brighten the edges of your photos, ruining the print. Use this test to verify that your monitor displays brightness evenly across the entire frame.
For Gamers
The "Dirty Screen Effect" (DSE) is visible when the camera pans across a uniform color (like a sky or football field). It looks like faint vertical bands or clouds. This test helps you check for DSE and clouding on new gaming monitors within the return window.
Common Uniformity Defects
1. Backlight Bleed
Light leaking from the edges of the screen, common in IPS panels. It destroys black levels and is most visible in dark rooms.
2. Clouding (Mura)
Uneven patches of brightness that look like white clouds on a dark background. This is often caused by uneven pressure from the monitor bezel or poor manufacturing.
3. Color Tinting
When one side of the screen looks warmer (yellow/red) and the other looks cooler (blue). This makes color grading impossible.
Frequently Asked Questions
What is an acceptable uniformity level?
For professional work, brightness deviation should be under 10%. For general use, up to 15-20% is often acceptable. If you can see the unevenness with your naked eye during normal use, it's likely a defect.
Can I fix screen uniformity issues?
Hardware uniformity issues (like bleed or clouding) are usually permanent. However, some high-end monitors have a "Uniformity Compensation" setting in the OSD menu that digitally corrects brightness at the cost of contrast ratio.
Does OLED have uniformity issues?
OLEDs have perfect black uniformity (no bleed), but they can suffer from "vertical banding" in near-black grays (5-10% gray) and color tinting on white screens due to panel variance.