Stephen Harrison 🗓️ Updated ⏱️ — 📝 —


5 Percent Grey Uniformity Test — Spot DSE, Vertical Banding & Tint Issues

If your monitor looks “patchy” in dark scenes, shows vertical bands during panning, or has uneven tint, this 5 percent grey uniformity test helps you confirm it in minutes.

Open the tool, go full-screen, and let the patterns sweep the display so you can spot dirty screen effect (DSE), banding, and uniformity problems that are easiest to see on near-black grey.

You’ll then know what you’re dealing with and what to try next (settings checks, cables/ports, HDR mode, or warranty/returns if it’s new), without installing anything or sharing data.

What To Do If The 5 Percent Grey Uniformity Test Shows You A Problem With Your Screen

  • If you see a bright/coloured dot on dark screens (stuck pixel): re-check after a reboot, then try short runs of colour-cycling/pixel-fixer content; if it’s new and still obvious, check the retailer/manufacturer pixel policy and return/exchange within the warranty period.
  • If you see patchy blotches or vertical bands on the 5% grey screen (DSE / banding / uniformity): disable Eco/ambient light settings, test at your normal brightness (then slightly lower), and compare different inputs/cables/HDR modes. If it is a new display, and you can’t “unsee it” in real content, treat it as a return/replace decision.
  • If black screens look glowy in corners or edges (bleed/glow): check straight-on vs off-angle, lower brightness a touch, and ensure local dimming/black level settings aren’t mis-set. For OLED screens, avoid leaving static patterns paused for long and use built-in pixel refresh tools if the TV/monitor provides them.

Screen Test Patterns (5 Percent Grey Uniformity Test)

Use full-screen colour blocks and smooth gradients to spot dead/stuck pixels, banding, tint issues and sharpness problems. Works on phones, tablets and PCs — and it runs entirely on your device.

Dead & stuck pixels

Solid colours + a moving “pixel walker” make bright/dark dots easier to notice.

Banding & gradients

Multiple smooth ramps help reveal steps, posterisation and panel uniformity issues.

Sharpness & clarity

Fine lines, checkerboards and text patterns can reveal blur, scaling and focus issues.

Quick tips before you start
  • Clean the screen first — dust can look like dead pixels.
  • Set brightness to your normal level (then try a higher level).
  • For OLED screens: don’t leave static patterns on for long (avoid burn-in).
  • Use keyboard shortcuts: ←/→ pattern, F full-screen, Space hide UI, Esc exit.

What the results mean (quick help)

Dead pixel (always dark)
Stuck pixel (always bright/coloured)
Banding (visible “steps”)
Backlight bleed (bright corners on black)
What’s the difference between a dead pixel and a stuck pixel?

Dead pixel: usually stays black on every colour screen. Stuck pixel: stays bright or coloured (often red/green/blue) and shows up on dark backgrounds.

If it’s a new device, check the manufacturer’s pixel policy and warranty. If it’s out of warranty, you can try:

  • Gently cleaning the screen (dust can mimic a pixel).
  • Running a “pixel cycling” pattern/video for a short period.
  • Avoid pressing hard on the panel (that can make things worse).
I can see “steps” in gradients — is that bad?

That’s banding. Mild banding can be normal on some panels, but heavy stepping can be caused by:

  • Limited colour depth (8-bit panels) or wrong display mode
  • GPU driver settings / dithering / HDR mode
  • Streaming/compressed content (less relevant here because this tool is local)

Try changing: HDR on/off, different refresh rate, different cable/port, or resetting display/GPU colour settings to default.

What if black screens look “glowy” or bright in the corners?

On LCDs this can be backlight bleed (fixed bright patches) or IPS glow (changes with viewing angle).

  • Lower brightness a little and re-check.
  • View straight-on (IPS glow increases off-angle).
  • If it’s severe on a new device, consider warranty/returns.
Text/lines look fuzzy or “shimmery” — what should I check?
  • Use the display’s native resolution (e.g., 1920×1080 on a 1080p panel).
  • Set OS scaling to a sensible value; test at 100% if practical.
  • On Windows: run ClearType tuner.
  • For TVs used as monitors: ensure PC mode / 4:4:4 chroma if available.
Is it safe to leave these patterns running?

Generally yes for LCD/LED screens. For OLED, avoid leaving static images up for long periods — use auto-advance and don’t pause on a single pattern for too long.

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