Run Uniformity Test
Screen Color Uniformity Test is a free display inspection tool that helps you detect backlight bleed, dirty screen effect, tint shift, and banding on monitors, TVs, laptops, and phones. It generates fullscreen solid colors and low-contrast patterns directly in your browser. Keep your display brightness steady while testing.
Inspection Notes
Use notes to document what you see during each pattern. Notes stay in your browser tab and are never uploaded.
What To Look For
| Issue | Usually most visible on | What it can look like |
|---|---|---|
| Dirty Screen Effect (DSE) | Mid gray + vertical bands | Cloudy patches or streaks that make panning scenes look uneven |
| Tint Shift | Near white or gray | One side looks warmer/cooler (yellow, pink, green, or blue cast) |
| Backlight Bleed / Glow | Near black in dark room | Brighter corners or edge glow when image should look uniform |
| Banding | Horizontal/vertical bands | Hard transitions between stripes instead of smooth gradation |
| Mura / Uniformity Noise | Checker + low intensity | Fine blotches or grain-like bright/dark inconsistency across panel |
About This Screen Uniformity Test
Screen Color Uniformity Test is a free browser-based display inspection tool that helps you check whether your monitor, TV, laptop, tablet, or phone displays brightness and color evenly across the entire panel. It supports solid-color fills, low-contrast banding patterns, gradient checks, and a checkerboard mode for detecting mura. It does not require installation, sign-up, or any data upload.
Use solid near-white and mid-gray first. Those are usually the fastest way to spot tint differences, dirty screen effect, and edge darkening. Then test near-black in a dim room to check for backlight bleed or IPS glow. Pattern modes intentionally add weak contrast variation so uneven regions become easier to notice, especially when comparing center versus edges.
This is a practical inspection tool, not a hardware calibration device. It does not replace a colorimeter for precise color management, but it is effective for acceptance checks on new monitors, troubleshooting panel lottery issues, or comparing two displays side by side. For consistent results, disable adaptive brightness and any dynamic contrast features before testing.
Worked Example
A user purchases a 27-inch IPS monitor and wants to verify panel quality before the return window closes:
- Set monitor brightness to 120 nits (roughly 40-50% on most panels) and disable dynamic contrast.
- Open this tool and select Near White + Solid Fill. Scan corners: a slight warm tint in the bottom-left corner is noted.
- Switch to Mid Gray + Vertical Bands. Faint cloudy streaking appears in the left third of the screen — mild dirty screen effect.
- Test Near Black in a dark room using fullscreen. Two corners show a faint glow that shifts when moving viewing position — typical IPS glow, not backlight bleed.
- Conclusion: Panel has minor DSE and normal IPS glow. Acceptable for general use; borderline for color-critical photo editing.
How To Use
- Set your display to a fixed brightness level and disable auto-brightness.
- Start with Near White and Solid Fill, then scan corners, edges, and center.
- Switch to Mid Gray and Vertical Bands to reveal dirty screen effect.
- Test Near Black in a dark room to check glow and bleed behavior.
- Use notes to track findings and compare displays consistently.
Frequently Asked Questions
What does a screen uniformity test detect?
A screen uniformity test detects uneven brightness, dirty screen effect (DSE), color tint shift across the panel, backlight bleed at the edges, IPS glow in corners, and low-level banding in uniform tones. These issues are hard to spot during normal use but become obvious on solid-color test patterns.
Is this a hardware calibration tool?
No. It is a visual inspection tool, not a colorimeter-based calibration system. It helps you detect panel uniformity problems quickly, but it does not generate ICC profiles or calibrated measurements. For color-accurate work, use a hardware colorimeter after checking uniformity here.
Should I test in a dark room or bright room?
Use both. A dark room makes edge glow and backlight bleed easier to see on near-black fills. A moderately lit room can reveal real-world dirty screen effect and tint differences that appear during normal use. Testing in both conditions gives the most complete picture of panel quality.
Does this tool upload my display data?
No. Everything runs locally in your browser. No images, notes, or settings are sent to a server. The test patterns are generated client-side using an HTML canvas element.
What is dirty screen effect (DSE)?
Dirty screen effect is a manufacturing variation where different areas of an LCD panel transmit light unevenly. It appears as cloudy patches or vertical streaks on uniform mid-gray backgrounds. DSE is most visible when panning across solid colors in sports broadcasts or video games.
Can I use this test on a phone or tablet?
Yes. The test works on any device with a web browser, including phones, tablets, laptops, and external monitors. Use the fullscreen button for the most accurate results, and disable auto-brightness before testing.
What is the difference between backlight bleed and IPS glow?
Backlight bleed is light leaking around the edges of the panel where the frame presses against the LCD layers. It appears as bright spots along edges and does not change with viewing angle. IPS glow is a characteristic of IPS panels where corners appear lighter when viewed off-axis. IPS glow shifts as you move your head; backlight bleed stays fixed.
How do I know if my monitor uniformity is acceptable?
Minor tint variation and slight edge darkening are normal on most consumer panels. If you see large cloudy patches on mid-gray, bright spots on black that cover more than a small corner area, or noticeable color shift from one side to another on white, the panel may have above-average uniformity issues. Compare against a second display of the same model if possible.
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