Dead Pixel & Light Leakage Test
Use solid colors, gradients, and grids to examine screens for dead pixels, stuck pixels, and backlight bleeding. Essential for checking new monitors and phones.
Avoids unrelated permissions and runs in your browser with the device APIs available on this device.
Works best in current Chrome, Edge, Safari, and Firefox. Support depends on Canvas rendering checks, secure HTTPS, hardware availability, and browser policy.
How to use this page to find problems faster
Inspection Guide
Use primary colors to find stuck pixels; Black/Grey for light leaks.
Go to full screen and prepare the environment
Full-screen display with solid color background, it is recommended to select ambient light and brightness according to the target.
Scan dead pixels and color casts with solid color
In solid colors such as red/green/blue, dead pixels are easier to identify.
Use black/grey/white to observe light leakage and uniformity
Black/grey is more suitable for seeing light leakage and uneven backlight; white/light gray is more suitable for seeing dirty screens and color temperature shifts.
What this tool checks
This page helps you inspect the screen visually for dead pixels, stuck pixels, light bleed, and other easy-to-miss panel issues.
solid-color inspection
Lets you scan the panel against uniform backgrounds where dead or stuck pixels stand out more clearly.
bright and dark defect clues
Helps reveal pixels that stay black, white, or a fixed color when they should change.
gradient visibility
Useful for noticing obvious banding, unevenness, or panel artifacts.
edge glow and bleed check
Makes backlight bleed or corner glow more visible on dark full-screen backgrounds.
grid / alignment aid
Provides structured patterns that help reveal scaling and uniformity oddities.
manual screen scan workflow
Supports a deliberate user inspection before you accept a new monitor or phone screen.
What this tool cannot confirm
This is a visual inspection tool, so the result depends on your own observation and the room you are viewing the display in.
not automatic pixel counting
The page does not programmatically detect every faulty pixel for you; you still need to inspect the screen.
ambient light matters a lot
Light bleed, uniformity issues, and subtle defects are easier or harder to notice depending on room lighting.
panel technology affects expectations
IPS glow, OLED mura, and mini-LED blooming can look different without necessarily meaning the same defect.
cannot judge warranty policy
A visible defect does not automatically mean the manufacturer will replace the panel under their policy.
How the result is generated
The result is generated by rendering full-screen colors, gradients, and grids locally so that you can inspect the panel yourself.
pattern rendering
The page displays solid colors, gradients, or grids directly in the browser.
fullscreen viewing
You can inspect the panel more clearly when the test fills as much of the screen as possible.
visual scan
You move your eyes across the display to look for fixed dots, glow, or uneven regions.
pattern switching
Changing colors helps reveal whether a suspicious pixel remains fixed across different backgrounds.
manual conclusion
The final result depends on what you observed while viewing the rendered patterns.
Interpret your results
Use the observed defect pattern to decide whether you are seeing a stuck pixel, a dead pixel, bleed, or just normal panel behavior.
| Observed panel sign | Likely meaning |
|---|---|
| Fixed black dot | A likely dead pixel or permanently non-lighting subpixel cluster. |
| Fixed bright or colored dot | A likely stuck pixel that is staying on one state or color. |
| Corner glow on dark screens | Backlight bleed or panel glow that may be normal to a degree depending on panel type. |
| Visible banding in gradients | Limited smoothness, panel processing issues, or expected panel characteristics. |
| No obvious defect seen | The panel appears visually normal in the conditions you tested. |
Supported browsers and known limitations
This tool mainly depends on the browser rendering full-screen colors cleanly, so support is generally broad.
| browser | fullscreen color patterns | gradient / grid support | manual inspection flow | known limitations |
|---|---|---|---|---|
| Chrome | Strong | Strong | Strong | Browser UI chrome may still interfere unless fullscreen is used. |
| Edge | Strong | Strong | Strong | Display scaling can slightly affect how small patterns look. |
| Firefox | Strong | Strong | Strong | Color management differences may slightly change gradients. |
| Safari | Strong | Strong | Strong | Auto-brightness and True Tone style features can influence perception. |
| iOS Safari | Strong | Good | Good | System gestures and brightness control can interfere with edge inspection. |
| Android Chrome | Strong | Good | Good | Mobile brightness and OLED behavior can alter what you notice. |
Use cases
This test is most useful when you need a deliberate visual inspection workflow for a display before relying on it.
after buying a new monitor
Inspect the screen for pixel defects or bleed before the return window closes.
after buying a new phone
Quickly scan for stuck pixels or uneven display areas on a fresh device.
when you notice a suspicious dot
Switch colors to confirm whether the defect remains fixed across patterns.
before accepting office hardware
Run a quick visual screen check before taking a monitor into daily use.
after transport or repair
Re-check the panel if the device was shipped, moved, or recently serviced.
FAQ
A collection of frequently asked questions about dead pixels/light leakage/color uniformity inspection.
What are dead pixels/bright pixels/dark pixels?
Bad pixels usually refer to pixels or sub-pixels working abnormally: bright spots (always bright), dark spots (always dark), or color casts (a sub-pixel failure causes abnormal color). The performance will be different under different solid colors, so it is recommended to use red/green/blue to check separately.
Why use solid color full screen?
Solid colors can maximize the emphasis on "abnormal points" and "regional unevenness" on the screen. For example, black screens are most likely to see light leakage, white/grey screens are most likely to see dirty screens and uneven brightness, and RGB solid colors are most likely to see bad pixels and color casts.
What is the grid used for?
The grid can divide the screen into regular areas, helping you scan in the order of "left to right/top to bottom" to reduce omissions; it also makes it easy to locate and record the location of the problem.
How to measure light leakage more accurately?
It is recommended to use a pure black or dark gray full screen in a dark environment, and adjust the screen brightness to the mid-to-high range you usually use (or the level you want to compare). Be careful to differentiate between "normal IPS grey/glow" and distinct edge light leaks/cloudy patches.
Full screen may fail on mobile phone/tablet, what should I do?
Some mobile browsers have limitations on the Fullscreen API (especially iOS Safari). You can still scroll the page to the maximum display area and manually hide the browser UI; or switch to a browser/desktop with better support and test again.
Does this page collect my screen data?
Won't. The essence of "detection" here is to display a specific color/grid pattern to help you see it with the naked eye. All rendering is done locally in the browser, with no need to upload any images or device data.
What to do after discovering bad pixels?
It is recommended to record the location (grid assist), review it in different colors, and take photos as evidence (be careful to avoid the influence of the camera's automatic exposure). If it is within the warranty/return period, you can communicate with after-sales accordingly.
Related guides
Read a few practical guides for setup, browser compatibility, and troubleshooting around this test.
The Hidden Flaws in Your Display: A Complete Guide to Dead Pixel and Light Leakage Testing
Discovering a dead pixel or severe light leakage on a brand-new monitor can be frustrating, but catching these issues early is crucial for warranty claims and visual comfort. This practical guide explores why screen quality verification matters for everyone from gamers to graphic designers. We break down the science behind stuck pixels and backlight bleeding, explaining how solid color cycles and gradient tests reveal hidden defects that standard usage might miss. Step-by-step, you will learn how to utilize online testing tools to inspect new purchases, verify post-repair quality, or evaluate second-hand devices. Whether you are setting up a professional design station or simply ensuring your home entertainment setup is flawless, this article provides the essential workflow to identify screen anomalies, document evidence for returns, and ensure you are getting the display quality you paid for.
The Hidden Flaws in Your Display: A Complete Guide to Dead Pixel and Light Leakage Testing
Discovering a defect in a brand-new monitor or smartphone screen can be frustrating. This practical guide explores the critical importance of performing dead pixel and light leakage tests immediately after purchasing a device or completing a repair. We break down how solid color cycles, gradients, and grid patterns reveal hidden issues like stuck pixels and backlight bleeding that often go unnoticed during casual use. Whether you are a graphic designer requiring perfect color uniformity, a gamer checking for distractions in dark scenes, or a consumer verifying a second-hand purchase, this article provides step-by-step instructions on using online tools to validate screen quality. Learn how to document these flaws effectively to ensure you can claim warranties or negotiate returns before it's too late.
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