How do I find dead pixels on my monitor?

Use solid color test screens (red, green, blue, white, black) and look closely for pixels that don't match the background color.

What is a stuck pixel vs a dead pixel?

Dead pixels are always black. Stuck pixels are always lit in one color (red, green, or blue).

Can stuck pixels be fixed?

Sometimes. Try pixel-fixing tools that rapidly flash colors. Dead pixels usually cannot be fixed.

Screen diagnostics

Free Open Source Monitor Color Test

Cycle through 14 color panels to check color accuracy, gradient banding, backlight uniformity, and contrast.

View testing tips

Pure Black 1/14

Jump to a test:

Tip: Press F to go fullscreen, → / Space for next, ← for previous. Click anywhere on the panel to advance. For accurate results, dim room lighting and let your monitor warm up for 15 minutes.

14 color tests

Solids, gradients, ramps & patterns

Fullscreen mode

Edge-to-edge panel inspection

Works on any display

Monitor, laptop, tablet or TV

No download needed

Runs entirely in your browser

What to Look for During the Color Test

Each test panel targets a specific display defect. Here is what to watch for on each one.

Pure Black

Look for grey or light patches, especially near the edges and corners. Bright spots indicate backlight bleed — light leaking through the LCD panel where it should be blocked.

Pure White

Check for uneven tinting across the panel. Yellow or pink patches in corners or at the edges suggest poor backlighting or failing LEDs. A uniform white is expected on a healthy display.

Red / Green / Blue

Look for uneven brightness across the panel (called uniformity). Areas that appear brighter or darker than the rest suggest uneven backlighting or local dimming issues.

Gradient Tests

Watch for visible bands or steps instead of smooth transitions — this is called color banding. It indicates a 6-bit panel that uses dithering to simulate colors it cannot display natively.

What Is Color Banding?

Color banding occurs when a monitor cannot display smooth gradients, producing visible steps or stripes instead of a continuous transition.

6-bit TN

Budget panels

6-bit TN panels display only 262,144 true colors and use dithering to simulate more. Gradient tests almost always show visible banding on these displays.

8-bit IPS/VA

Mid-range panels

8-bit IPS and VA panels display 16.7 million true colors. Gradients usually appear smooth, though slight banding can still appear on low-quality units in very dark tones.

10-bit HDR

Professional / HDR panels

10-bit HDR panels display over 1 billion colors. Gradients are always perfectly smooth. Color banding on these displays would indicate a driver or GPU output issue, not a panel defect.

Backlight Bleed vs IPS Glow

Both appear during the Pure Black test but have different causes and different implications for your display.

Backlight Bleed

Bright white or light-coloured patches at the edges or corners of a pure black screen. Caused by physical gaps in the panel assembly that allow backlight to leak through. Severe bleed may qualify for a warranty replacement.

IPS Glow

A silver or golden shimmer visible only at extreme viewing angles near the corners of an IPS display. This is a normal characteristic of the IPS panel technology, not a manufacturing defect, and is not covered by warranties.

How to Test

Select the Pure Black test panel and view it in a dimly lit or dark room. Backlight bleed is visible head-on; IPS glow appears only when you tilt or look at the screen from the side at a shallow angle.

Warranty Claim

Document bleed patches in a photo taken head-on in a dark room. Most manufacturers consider bleed a defect only if it is visible under normal use conditions. Extreme bleed that is distracting during everyday use is typically covered.

Monitor Calibration After This Test

If colors look inaccurate, these steps will help you improve display quality.

Use your monitor's OSD

Access the On-Screen Display menu (usually a button on the monitor bezel). Adjust color temperature (try 6500K for standard use), brightness, and contrast to match what you see in the test panels.

Windows / macOS calibration

Both operating systems include a built-in display calibration wizard. On Windows, search for "Calibrate display color." On macOS, go to System Settings → Displays → Color → Calibrate.

Hardware colorimeter

For professional or color-critical work, use a hardware colorimeter such as a Datacolor Spyder or X-Rite i1Display. These devices measure the actual light output and create a custom ICC color profile for your specific panel.

Also useful: Dead Pixel Test — check for dead and stuck pixels using fullscreen solid colors. | Refresh Rate Test — measure your monitor's actual refresh rate.

More testing tools

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