Black Screen, White Screen & Dead Pixel Tester
Test your monitor for dead pixels, backlight bleed, and color uniformity with pure black, white, and RGB screens in fullscreen. 100% free and private.
Display Preview Canvas
Inspect color fields, gradients, and dead pixel targets in real-time.
Pure Black
#000000
RGB: 0, 0, 0
Color Presets & Diagnostic Swatches
Select high-contrast fields to pinpoint dead pixels (black), stuck pixels (RGB), and backlight bleed.
Keyboard Hotkey Matrix
Display Diagnostic & Inspection Guide
How to Detect Dead Pixels
Switch to Pure White in Fullscreen. Dead pixels remain permanently unlit and appear as tiny black or dark dots against the bright background. Clean your screen first to ensure it is not surface dust.
How to Detect Stuck Subpixels
Switch to Pure Black in a darkened room. Stuck subpixels remain permanently energized and glow brightly as red, green, or blue microscopic specks.
Backlight Bleed & IPS Glow
View a black screen in the dark. Light leaking from the monitor frame edges is backlight bleed. If the corner brightness shifts when you change your viewing angle, it is harmless IPS glow.
Color Banding & Uniformity
Switch to Horizontal Grayscale Gradient. Inspect for smooth, seamless tone transitions from black to white. Harsh visible vertical steps indicate 6-bit panel dithering or compression artifacts.
Frequently Asked Questions
A dead pixel is permanently unpowered and appears as a black or dark dot on bright backgrounds (most visible on pure white). A stuck pixel has one or more subpixels permanently energized, causing it to glow red, green, blue, or yellow against a dark background (most visible on pure black).
Backlight bleed occurs when the display panel's backlighting leaks around the edges or corners of the monitor frame due to uneven mechanical pressure or panel assembly tolerances. While severe bleed cannot be repaired without replacing the panel, loosening over-tightened VESA mount screws can sometimes relieve bezel pinch.
True dead pixels (where transistors are completely unpowered) rarely fix themselves. However, stuck subpixels occasionally unstick with time, normal screen usage, or cycling through RGB colors.
Set the screen to pure white or pure black in fullscreen mode to make dust specks, fingerprints, and smudges stand out clearly. Use a dry, lint-free microfiber cloth and wipe gently without applying excessive pressure.
Yes! The entire testing suite, color generation, auto-cycle slideshow, and fullscreen controls execute 100% locally in your browser. Zero display data or telemetry is sent to any remote server.