Set up the test properly
- Clean the screen and let the monitor warm up for a few minutes.
- Set the panel's native resolution and browser zoom to 100%; note any OS display scaling.
- Use your normal brightness; dim the room for the black/uniformity patterns.
- Disable night-light/blue-light filters and any "dynamic contrast" mode.
- Move through all ten patterns; each overlay hint says what to look for.
What each pattern reveals
Solid colors (black, white, R, G, B, gray)
Dead pixels (black dots on white), stuck subpixels (colored dots on black), backlight bleed and clouding on black, tint and dirty-screen effect on gray.
Grayscale gradient
Smoothness of tonal reproduction. Distinct vertical bands indicate bit-depth limits, signal-range mismatch, or processing artifacts.
RGB gradients
Per-channel banding and crushed shadows near black — compare where each color band stops being distinguishable from black.
CSS-pixel checkerboard & text
Browser rendering and text sharpness. Zoom, display scaling, and pixel density affect the checkerboard; an even pattern does not prove a 1:1 mapping to display pixels.
Next steps
Pixel defects deserve their own careful pass — the dedicated dead pixel test walks through dead-versus-stuck identification and warranty guidance. Testing a touch-enabled display? Verify the digitizer with the touch screen test. Banding or color problems that survive a factory reset and correct signal settings are panel-level: document them with photos for a warranty conversation.
Monitor test questions
Ten fullscreen patterns cover the common panel checks: solid black, white, red, green, blue, and gray for dead or stuck pixels and backlight uniformity; a grayscale gradient and RGB gradients for banding and bit-depth problems; a checkerboard with squares of one CSS pixel for inspecting browser rendering; and multi-size text for sharpness and fringing.
Banding is visible steps in what should be a smooth gradient. Causes include a 6-bit panel (with or without dithering), a limited-range signal on a full-range display (or vice versa), aggressive contrast/sharpness settings, or graphics-driver color settings. Try the monitor’s factory reset and check the GPU output is set to full RGB before blaming the panel.
Each square is one CSS pixel, which can cover several physical pixels on a high-density display. Browser zoom, display scaling, and pixel density can change how the pattern looks. Try the panel’s native resolution and 100% browser zoom for a consistent check, but shimmering or moiré alone does not prove a display fault or an incorrect resolution.
Use the black pattern in a dim room at normal brightness: glow along edges or in corners is backlight bleed, and cloudy patches are uniformity defects. Some bleed is normal on LCDs — judge whether it is visible in dark scenes at your usual brightness. The 50% gray pattern reveals dirty-screen effect and tint shifts across the panel.
On the text pattern, characters should be crisp with no colored fringes or double edges. Fuzziness usually comes from non-native resolution, fractional display scaling, an oversharpening setting on the monitor, or a VGA/legacy connection. Prefer DisplayPort/HDMI, native resolution, and the monitor’s neutral sharpness setting.