How to Read UFO Test Results: Motion Blur, Ghosting, etc

If you have ever searched for ways to check your monitor’s motion clarity, you have probably encountered UFO Test—the industry-standard web demo created by Blur Busters. Running it is simple: open a browser, pick a pattern, and watch the little green UFO glide across the screen. Reading the output, however, is where most people get lost. This guide teaches you how to interpret each data field, spot visual artifacts such as motion blur and ghosting, and decide what to tweak—or when to upgrade.

1. A Two-Minute Primer on How UFO Test Works

1. Frame Delivery – The test animates the UFO sprite at a known pixel speed (e.g., 960 px /s).
2. Browser Timers – JavaScript measures the exact refresh rate and frame pacing.
3. Human Vision – Eyes integrate light over time (persistence). Shorter persistence ⇒ sharper motion.

2. Key Read-Outs on the Main Test Page

3. Motion Blur: Why the UFO Smears

3.1 Blur Length Formula

Blur length ≈ Object speed × Eye tracking time

The faster the UFO moves or the longer each frame persists, the longer the smear. Authoritative reading: Blur Busters’ article on display persistence vs. response time.

3.2 How to Judge

1. Pause the test with Space, advance frame-by-frame using ←/→.
2. Measure the smear tail in pixels using a screen-ruler extension.
3. Compare against reference values:
   • 60 Hz at 960 px/s ≈ 16 px (normal)
   • 144 Hz ≈ 7 px  •  240 Hz ≈ 4 px

4. Ghosting: Dark or Bright Echoes Behind the UFO

Ghosting occurs when pixels cannot transition fast enough, leaving residual images:

• Dark Ghosts – darker duplicate.
• Inverse Ghosts / Coronas – bright halos from overdrive overshoot.

See the JEITA gray-to-gray measurement standard (JEITA).

4.1 Measuring Severity

1. Record the screen in slow motion (≥240 fps).
2. Step through frames in VLC; count frames the echo persists.
   ≤2 frames = good, 3–4 = acceptable, >4 = noticeable smearing.

5. Overdrive: Your Best Friend—Until It Isn’t

Overdrive (OD) applies extra voltage to accelerate pixel transitions. Typical labels: Low / Normal / High.

Authoritative resource: NVIDIA G-SYNC Variable Overdrive white-paper.

5.1 Finding the Sweet Spot

1. Run UFO Test at max refresh rate.
2. Cycle OD levels; photograph results.
3. Select the highest level with no bright coronas.

6. Common Pitfalls & Fixes

7. When It’s Time to Upgrade

If you still see:

• Blur length > 8 px at 240 Hz, or
• Persistent inverse ghosting regardless of OD,

the panel’s native response is the bottleneck. Modern Mini-LED or OLED monitors achieve <1 ms GtG and support strobing without coronas. Check out Mobile Pixels’ latest gaming monitors for fast-response displays verified by independent reviewers.

8. Quick Reference Cheat-Sheet

• Acceptable Blur Length: ≤7 px @144 Hz, ≤4 px @240 Hz
• Ghosting Frames: ≤2 = excellent; 3–4 = moderate; >4 = poor
• OD Tuning Order: Off → Medium → High → Highest (stop when coronas appear)

9. FAQ

Q: Does UFO Test measure input lag?
A: No. Use tools such as NVIDIA LDAT or a high-speed-camera LED method.

Q: Why is the MPRT box red?
A: The test detected <95 % frame-pacing accuracy (browser or OS power saving).

Q: Can I trust phone recordings?
A: They are fine for qualitative comparison. For scientific numbers, you need ≥1000 fps and a photodiode setup per Blur Busters pursuit-camera method.

10. Conclusion

The UFO Test turns any desktop into a mini motion lab. By understanding its metrics—refresh alignment, blur length, ghosting style, and overdrive artifacts—you can fine-tune your current monitor or make data-driven upgrade decisions. Happy testing, and may all your UFOs glide razor-sharp across the cosmos!