What Is a UFO Test?
A UFO test is a browser motion pattern used to inspect how moving content looks along the current browser, operating-system, graphics, connection, and display path. This implementation uses an original geometric capsule marker rather than a spacecraft illustration. The target travels at a selected number of CSS pixels per second across controlled tracks, making visible blur, trailing, smearing, and ghosting-like appearances easier to compare than they are in an unpredictable game scene.
The name is widely used for monitor motion tests, but it does not imply one standardized graphic, formula, or pass threshold. This page focuses on multi-track contrast conditions, selectable speed, direction, live browser cadence, and calculated travel per observed frame. It is a visual inspection aid. It does not photograph the panel, read internal overdrive settings, or automatically score a monitor.
What This Motion Test Shows
The moving object test gives your eyes a repeatable edge and internal detail to follow. A crisp moving marker may still look less defined than the same marker while paused because sample-and-hold presentation, eye tracking, pixel transitions, and temporal processing all affect motion appearance. A faint copy, colored edge, dark smear, or extended trail may become easier to notice when the background and target contrast change.
What you see belongs to the complete visible path, not one component in isolation. Browser scheduling determines update opportunities, the compositor places each target, the display receives frames through its active mode, and panel electronics produce light over time. The UFO test can reveal a repeatable appearance under stated settings, but it cannot identify which layer caused it or convert the observation into an exact response-time number.
How to Get Started
Place the browser entirely on the display you want to inspect and confirm the intended refresh mode in operating-system settings. Begin with three mixed-condition tracks at 480 px/s, select Start, and follow one marker with your eyes rather than staring at a fixed point. Pause at any time to compare the stationary shape. Then change one control—usually speed or background—while keeping the other conditions unchanged.
Use fullscreen when a larger uninterrupted motion area makes observation easier. Restart returns the target to the beginning, clears the bounded cadence sample, and starts a fresh run. If the page becomes hidden, motion pauses so a throttled background gap is not treated as ordinary cadence. People sensitive to motion should use short sessions, pause immediately if uncomfortable, and avoid treating this display tool as a medical test.
- Start with 480 px/s, three mixed tracks, and the browser fully on the intended monitor.
- Pursue the marker with your eyes, pause for a static reference, and note any repeated edge or trail appearance.
- Change only speed, contrast set, direction, or track count, then restart for a controlled comparison.
Motion Blur, Ghosting, Smearing, and Trailing
Motion blur is a broad description for reduced detail in moving imagery. On sample-and-hold displays, eye movement across an image held for most of a refresh can contribute perceived blur even when a transition is fast. Ghosting often describes a faint displaced remnant behind a moving object. Smearing commonly refers to a longer dark or colored extension, while trailing is a useful neutral term for a visible path following the marker.
These labels overlap in everyday use and are not diagnoses by themselves. Overdrive can produce a bright or inverted-looking edge, slow transitions can leave a darker continuation, and browser or display processing can create other temporal patterns. A screen ghosting test should therefore record direction, speed, contrast, refresh mode, brightness, and picture settings. Avoid assigning a cause from the name of one artifact alone.
What Pixels per Frame Means
Pixels per frame provides context for how far the marker advances between browser-observed animation opportunities. The page calculates pixels per frame ≈ selected speed in px/s / observed browser FPS. At 480 px/s and an observed 60 FPS, the value is about 8 CSS pixels per frame. At the same speed near 120 FPS, it is about 4. Smaller steps can make the sampled motion path appear more continuous.
This is a calculated browser quantity, not a count of physical panel pixels or a presentation capture. The denominator comes from recent requestAnimationFrame() intervals and is kept in a bounded history. Device pixel ratio and scaling can make one CSS pixel cover a different number of device pixels. Cadence can also vary with load, visibility, window placement, power mode, and compositor policy, so read the value as test context rather than a hardware specification.
How Speed and Contrast Change What You See
Higher speed increases the distance traveled during each observed frame and asks your eyes to track a faster target. That can make blur or separation easier to see, but it can also make accurate pursuit harder. The 240, 480, 720, 960, and 1200 px/s presets cover a useful range without rapid flashing. A validated custom value from 60 to 2400 px/s supports a repeatable special case rather than unlimited or unsafe animation input.
Contrast affects transition difficulty and visibility. A dark target on a light field, a light target on a dark field, and a colored target on mid-gray can expose different-looking trails. The mixed setting deliberately assigns distinct conditions to separate tracks; it does not clone the same lane three times. Light, dark, and gray sets keep one background family while varying target contrast, which helps test a specific picture mode or content condition.
UFO Test vs Motion Blur Test
The motion blur test is a simpler controlled pursuit target intended to isolate perceived motion clarity at a consistent speed and selected background. This UFO test adds richer comparison controls: up to three contrast tracks, more speed presets, custom validation, direction, observed cadence, and pixels-per-frame context. Use the simpler page when one pursuit pattern is enough and this page when contrast-dependent trails are the question.
Neither page measures motion-picture response time, gray-to-gray transition time, moving-picture resolution, or overshoot as a calibrated instrument would. Both depend on the viewer and visible browser path. Repeatable visual differences can help compare settings on the same display, but a universal pass/fail line would ignore refresh mode, brightness, panel technology, processing, target design, pursuit quality, and individual perception.
UFO Test vs FPS Comparison
The FPS comparison displays multiple target update rates at the same travel speed. Its main question is how temporal sampling differs among 30, 60, 120, 144, or other selected FPS targets. Each lane can use a different target rate, while speed stays equal. The UFO test instead uses the browser’s current observed cadence and compares background or contrast conditions at one selected speed.
Choose FPS comparison to learn why a lower update rate advances in larger steps or to compare rate quantization on the current screen. Choose the monitor ghosting test when you want repeated passes across light, dark, and midtone tracks while changing speed. These tools may look related because both move shapes, yet their controlled variable and interpretation are intentionally different.
Why Browser Motion Cannot Measure Exact Panel Response Time
Exact panel response measurement requires a defined transition, synchronized stimulus timing, and an optical sensor with sufficient temporal resolution. This browser page has none of those measurement inputs. It does not know when a physical scan reaches a pixel, how voltage changes inside the panel, when emitted light crosses a threshold, or how firmware overdrive shapes the transition. An animation callback timestamp only reports a browser scheduling opportunity.
Display response claims can also use different conventions, including gray-to-gray ranges, best-case transitions, average transitions, or moving-picture methods. A visible trail cannot be safely converted to milliseconds by counting its apparent length on this page. Browser zoom, DPR, OS scaling, compositing, refresh cadence, synchronization, variable refresh, frame interpolation, and display processing remain between the CSS animation and the light reaching your eyes.
Who Can Use This Test?
Gamers can compare monitor overdrive or picture-mode settings before returning to game-specific testing. Display buyers can inspect a new or used monitor under controlled motion. Designers and developers can see how high-contrast interface movement appears on the active path. Support staff can ask a user to repeat one documented condition. In every case, the result describes this visual test rather than predicting every game, video, or desktop animation.
The test is not suitable for medical assessment, seizure screening, vision diagnosis, or ergonomic clearance. It avoids rapid flashing and provides visible Start and Pause controls, but continuous motion can still be uncomfortable. Keyboard users can reach every setup control and action, status is conveyed in text rather than color alone, and reduced-motion preference is acknowledged by keeping the test stopped until the user deliberately starts it.
Tips for Repeatable Comparisons
Record browser version, monitor, refresh mode, connection, resolution, scaling, brightness, picture mode, and the selected speed and contrast. Let the display reach its normal operating state. Keep the window on one monitor, close unrelated heavy work only when you want an idle baseline, and repeat each condition more than once. A phone recording can change exposure and introduce rolling-shutter bands, so treat it as documentation rather than a calibrated reading.
Change one variable at a time. If comparing overdrive modes, keep speed, direction, background, brightness, and camera or viewing position stable. If comparing refresh modes, confirm the operating system actually applied the new mode and use the refresh rate test as a browser-observed cadence check. Look for consistent differences across passes rather than selecting one unusually clear or blurry moment.
Related Display Tests
Use the motion clarity page for a focused pursuit target and FPS comparison for controlled target-rate lanes. The screen tearing test presents moving edges and scan guides for visual discontinuities, a different phenomenon from a transition trail. Use the dead pixel test for static point-like anomalies and the monitor test for gradients, tonal separation, sharpness, geometry, and uniformity.
A good workflow starts with the specific question. Static suspicious point, broad dark-field glow, gradient steps, cadence, tearing, and motion trails require different patterns and different limits. This UFO test answers how controlled moving content looks on the current browser/display path. It does not certify the display, inspect firmware, or replace an instrumented laboratory measurement when exact temporal performance matters.