Dead Pixel Test

Cycle through 8 solid colors to instantly find dead, stuck, or hot pixels on any monitor, TV, or phone screen.

What it does

8-Color Test Suite

Cycles through white, black, red, green, blue, yellow, magenta, and cyan — the colors that reveal every type of subpixel defect by activating different combinations of the RGB channels.

Adjustable Speed

Set the cycle speed from 1 second to 10 seconds per color. Slower speeds give you more time to carefully scan large displays; faster speeds are better for the stuck-pixel exerciser mode.

Manual Navigation

Use arrow keys or the on-screen buttons to step forward and backward through colors manually, staying on any color as long as you need.

Stuck Pixel Exerciser

Rapidly flashes RGB colors in a 4px area that follows your cursor, attempting to unstick a stuck pixel by cycling it between voltage states many times per second.

Color Name Overlay

A small label in the top-left corner shows the current color name and hex code so you can track which channel you're testing.

How to use Dead Pixel Test

  1. 1
    Open the test

    Navigate to devzone.tools/tools/dead-pixel-test.

  2. 2
    Enter fullscreen

    Click "Start Test" or press F to enter fullscreen. The screen fills with white.

  3. 3
    Scan each color

    Let the colors auto-cycle, or use arrow keys to advance manually. Look for any dot that does not match the background color.

  4. 4
    Mark defective pixels

    If you spot a suspect pixel, pause on that color and note its position. The overlay shows you the current test color.

  5. 5
    Try the exerciser (optional)

    Enable exerciser mode and hover the cursor over any stuck pixel. Leave it running for 10–30 minutes.

When to use this

New monitor acceptance test

Before your return window closes, run all 8 colors in fullscreen to detect any factory pixel defects. Most manufacturers honor warranty claims with 3+ dead pixels depending on ISO class.

Used monitor purchase

Before buying a used display online or in person, run the dead pixel test to assess pixel health and set realistic price expectations.

Attempting to fix a stuck pixel

Enable exerciser mode, hover over the stuck pixel, and leave it running for 10–30 minutes. The rapid voltage cycling sometimes unsticks pixels that are partially functional.

Warranty documentation

Screenshot or record the dead pixel test video to document defects for a manufacturer warranty claim or retailer return.

Periodic display health monitoring

Run the test every few months to track whether pixel count is increasing — a sign of a failing display panel that warrants proactive replacement planning.

ISO 9241-307 and What It Means for Your Dead Pixel Warranty

The International Organization for Standardization defines pixel defect tolerance in ISO 9241-307, the ergonomic standard for visual display terminals. It classifies pixel defects into three types: Type 1 (always bright), Type 2 (always dark), and Type 3 (adjacent defective subpixels).

Four defect classes define acceptable thresholds per million pixels. Most consumer monitors are sold as Class II, which permits a small number of defects. Understanding this standard matters because a monitor with 2 dead pixels might be technically within specification even though it is visually annoying. For critical professional work — medical imaging, photo editing — look for monitors sold as Class I or with zero-defect guarantees.

Why You Should Test a New Monitor Within the Return Window

Monitor manufacturers and retailers typically offer a 7-to-30-day return window from purchase. Dead and stuck pixels occasionally appear at the factory but become visible only after the first hours of use as the panel warms up and settles.

Running the dead pixel test within the first 24–48 hours of use protects you. After the return window closes, you are dependent on the manufacturer's warranty dead pixel policy, which may only cover defects above a certain count. Running the test immediately gives you maximum flexibility to return, exchange, or document the issue.

Frequently Asked Questions

What is the difference between a dead pixel and a stuck pixel?

A dead pixel is permanently off — it appears as a black dot on any color background because no subpixels are receiving voltage. A stuck pixel is always lit in one color — it receives constant voltage and displays one color regardless of the image. Hot pixels are a type of stuck pixel that always appear white or very bright. Dead pixels are generally harder to fix; stuck pixels can sometimes be exercised back to function.

What are the 8 test colors and what do they reveal?

White (#FFFFFF) reveals all three subpixels; black (#000000) reveals stuck-on subpixels; red (#FF0000), green (#00FF00), and blue (#0000FF) isolate each channel individually; yellow (#FFFF00) tests red+green without blue; cyan (#00FFFF) tests green+blue without red; magenta (#FF00FF) tests red+blue without green. Together, these 8 colors guarantee every possible subpixel combination is tested.

Can the stuck pixel exerciser actually fix pixels?

Sometimes. Stuck pixels occur because liquid crystals (in LCD) or organic compounds (in OLED) are "frozen" in one state. Rapidly cycling between voltage states can sometimes shake them loose. Success rate is roughly 20–40% for mildly stuck pixels. True dead pixels (physically damaged subpixels with no continuity) cannot be fixed this way.

How many dead pixels does it take to qualify for a warranty replacement?

ISO 9241-307 defines pixel defect classes. Most consumer monitors follow Class II or III: Class II allows up to 2 completely bright pixels or 2 completely dark pixels. Class III allows up to 5 bright pixels. In practice, many manufacturers have their own more lenient policies — check your specific manufacturer's dead pixel policy.

How do I document dead pixels for a warranty claim?

Take a screenshot in fullscreen mode (Cmd+Shift+3 on Mac, Win+PrtSc on Windows) and annotate the pixel location with an image editor. Also record a short video while cycling through all 8 colors to show the pixel is defective on multiple backgrounds, proving it is not an image artifact.

Does this work on phone screens?

Yes. On mobile, the tool enters soft-fullscreen mode covering the full viewport. The 8-color cycle works identically — tap to advance colors manually or let auto-cycle run. Phone screens are high-PPI so dead pixels are less visible but still detectable.

Why do some pixels appear as different colors on different test screens?

A pixel showing the wrong color on multiple test screens is likely a partial stuck pixel — one or two subpixels are stuck while others function normally. For example, a pixel that looks yellow on white (R+G without B) and dark on black indicates a stuck red and green subpixel with a dead blue. The exerciser may help.

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