Screen Issues
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Free Screen Test Tool

A dead pixel is a pixel on your screen that has stopped working and remains permanently dark. A bright spot, on the other hand, is an area that glows even when it should be black. Backlight bleed is light leaking from the edges of an LCD screen, while screen burn-in leaves ghost images on the display. This free screen test tool helps you detect all of these issues by displaying pure solid colors — white, black, red, green, blue, and gray — across your entire screen. By cycling through each color, you can quickly identify whether your display has any defects. Use this tool on laptops, monitors, tablets, or smartphones to get a clear picture of your screen's health. The auto-cycle feature walks through all six colors hands-free, so you can step back and inspect your screen from a distance. Whether you just bought a new device or want to check an existing one before returning it, this tool gives you an immediate and reliable diagnosis.

How to Use This Tool

  1. 1

    Click "Fullscreen" to fill your entire screen with the current test color. Make sure to close any applications or windows you do not want visible during the test.

  2. 2

    Use the "Next" and "Previous" buttons or the left and right arrow keys on your keyboard to cycle through each color. Press Space to advance one step.

  3. 3

    Look carefully at each solid color screen for any dark spots, bright spots, lines, color tinting, or uneven brightness. Do not rush — spend a few seconds on each color.

  4. 4

    Use the brightness slider at the bottom of the fullscreen view to reduce brightness. At lower brightness levels, backlight bleed and uniformity issues become much more visible.

Screen Test Tool

White

#FFFFFF

Look for any dark spots, lines, or uneven brightness on a pure white screen.

← → Arrow keys to navigate | Space to advance | ESC to exit fullscreen

What to Look for on Each Color

Each test color reveals a different type of screen defect. Understanding what each color exposes helps you pinpoint the exact issue with your display.

White

Look for any dark spots, lines, or uneven brightness on a pure white screen.

Black

Check for bright spots, stuck pixels, or light leakage bleeding through dark areas.

Red

Dead pixels may appear as tiny dark dots against the red background.

Green

Examine the entire screen for any abnormal bright or dark regions.

Blue

Blue helps reveal backlight unevenness and color uniformity issues.

Gray

Gray tests for subtle banding, uniformity problems, and faint bright spots.

Common Screen Defects

These example images show how various defects appear on your screen.

Comparison of normal pixel, dead pixel, and stuck pixel with labeled subpixel diagrams
Normal pixel vs dead pixel vs stuck pixel — each displays a different visual pattern on solid backgrounds
Annotated overview of multiple screen defects: dead pixel, bright spot, and backlight bleed labeled on screen
Common screen defects at a glance — dead pixel, bright spot, and backlight bleed labeled for easy identification
LCD screen showing a dead pixel as a tiny black dot on white background with zoom annotation
Dead pixel shown on a white screen — appears as a small black dot that never changes color
LCD screen showing a bright spot glowing on black background with zoom annotation
Bright spot visible on a black screen — a glowing white area that should be dark
LCD screen showing backlight bleed light leaking from bottom and corner edges
Backlight bleed on a black screen — light leaking from the edges and corners of the display
Gray screen uniformity test showing subtle color banding or tinting across the display
Gray uniformity test — any tinting, banding, or uneven brightness indicates panel defects

Frequently Asked Questions

How do I know if I have a dead pixel?
A dead pixel appears as a small dark dot that never changes color, no matter what is displayed on the screen. To confirm, display a pure white background — a dead pixel will remain black against the white. It will also appear on red, green, and blue backgrounds. If the dot is invisible on a black background, it may be a stuck pixel instead.
What is the difference between a dead pixel and a bright spot?
A dead pixel produces no light and appears as a dark or black dot. A bright spot, also called a light spot or white spot, glows on dark backgrounds where it should be dark. Bright spots are often caused by pressure on the screen, backlight bleeding, or dust trapped inside the display panel.
Can a dead pixel be fixed?
Dead pixels caused by complete transistor failure cannot be revived with software. However, if your pixel is stuck (showing one color instead of changing) rather than dead (showing nothing), pixel-fixing tools that rapidly cycle through colors may help. For truly dead pixels, screen replacement is the only solution.
What causes backlight bleed and how do I spot it?
Backlight bleed occurs when the backlight behind an LCD panel leaks light from the edges or corners, creating bright patches against dark backgrounds. To detect it, run the black screen test in a dark room. Reduce the brightness slider to 30–50% — severe backlight bleed becomes much more obvious at low brightness levels.
How many dead pixels are acceptable on a new screen?
Standards vary by manufacturer, but a common guideline allows up to 3 to 5 dead pixels depending on their location and the screen size. Apple, for example, will replace a MacBook screen if there are 6 or more dead pixels in a specific cluster. Check your manufacturer's warranty policy before the return window expires.
What causes black or green lines on my screen?
Black or green lines running across your screen are typically caused by a fault in the display panel's gate driver circuitry, a damaged ribbon cable connecting the panel to the motherboard, or in rare cases, GPU issues. Black lines are usually dead pixel rows or columns, while green lines may indicate a stuck row of green subpixels or a connection problem. These lines do not fade on their own and usually require professional repair or panel replacement.
Why is my screen showing an orange or tinted color?
An orange or unusual color tint on your screen usually points to a color calibration issue, a damaged ribbon cable affecting color channels, or in OLED panels, pixel degradation. If the tint appears on a gray background, check your display color settings. If it persists across all colors and inputs, it may be a hardware issue with the panel's color filter or backlight. Try a different cable or input source first to rule out a connection problem.
What is the difference between screen burn-in and image retention?
Image retention is a temporary ghost image that fades after a few minutes when the display shows a different image — it is caused by charge buildup in the pixel capacitors. Screen burn-in, on the other hand, is a permanent defect where the ghost image remains visible regardless of what is displayed, caused by wear on the phosphors in plasma displays or uneven aging in OLED panels. Both appear as faint outlines of previously displayed content, but only burn-in is permanent and irreversible.

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