ByteScope

Display & Monitor Test

Check your screen for defects and read out what your display really supports.

Your files never leave your browser — all processing is local.

Display info

Measured refresh rate
measuring…
Resolution (CSS px)
0 × 0
Physical estimate
0 × 0
Device pixel ratio
1.00
Viewport (live)
0 × 0
Color depth
0-bit
Pointer precision
coarse
Max touch points
0
Color gamut
unknown
HDR (display / video)
no / no

Gamut could not be detected by this browser.

Test patterns

  • Dead / stuck pixel

    A pixel that never changes on any color is dead; one stuck on a single hue is stuck — a healthy panel shows one flat, uniform color on every step.

    Click / space to cycle black → white → red → green → blue.

  • Uniformity / backlight bleed

    Turn brightness up and look for glow at the edges/corners on black, or dim patches on white — a healthy panel is flat and even edge-to-edge.

    Click / space to switch between pure black and pure white.

  • Banding / gradients

    A healthy 8-bit+ panel shows a smooth ramp; visible discrete steps or color casts in the ramp indicate banding or a poor color LUT.

    Click / space to cycle gray, red, green, blue 0–255 ramps.

  • Gamma chart

    Find the swatch where the striped half and solid half look equally bright when squinting — that column's number is your effective gamma (2.2 is the common target).

    No controls — read the chart at your normal viewing distance, then squint.

  • Ghosting / motion clarity

    A healthy fast panel keeps the moving blocks crisp; ghosting/blur trailing behind them at higher speeds indicates slow pixel response.

    Speed slider (1–16 px/frame), frame-locked motion.

  • Text sharpness

    Text should look crisp and evenly weighted at your normal scaling; blur, color fringing, or uneven stroke weight suggests a scaling or subpixel-rendering issue.

    Static — compare sizes 10–24px, sans & mono, both polarities.

  • Touch test

    Every touch/click should track smoothly with no dropped points, jitter, or dead zones across the whole surface — works with mouse too.

    Touch, pen or mouse — each contact gets its own color, ID and trail.

About this tool

This display test has two halves. The info panel reads out what your screen actually is: physical vs CSS resolution and pixel ratio, color depth, wide-gamut support (sRGB / P3 / Rec.2020), HDR capability, and the real refresh rate measured live from frame timestamps — often revealing that a "144 Hz" laptop panel is running at 60 Hz. The test patterns then let you inspect the panel itself, full-screen, one click at a time.

The patterns cover the checks reviewers and buyers actually run: solid-color cycles for dead and stuck pixels, pure black and white for backlight bleed and uniformity, per-channel gradients that make 8-bit banding visible, a gamma chart, a moving-object test for ghosting and motion clarity, text samples for sharpness at your scaling settings, and a multi-touch pad for touchscreens. Every pattern comes with a one-line guide on what to look for and what a healthy screen should show — most test sites give you the image and leave you guessing.

It's all generated in your browser with canvas and SVG — nothing to download or install, which makes it ideal for checking a new monitor before the return window closes, verifying a second-hand screen at handover, or diagnosing a panel that suddenly looks wrong.

Frequently asked questions

How do I check for dead pixels?
Run the solid-color cycle full-screen and step through black, white, red, green and blue with a click or the space bar. A pixel that stays black on every color is dead; one stuck on a single color shows up on the complementary screens. Wipe the screen first — dust is the classic false positive.
Can a stuck pixel be fixed?
Sometimes. Dead (always black) pixels are usually permanent hardware faults, but stuck subpixels occasionally recover after rapid color cycling or gentle massage with a soft cloth. Check your monitor's dead-pixel warranty policy — many manufacturers replace panels over a threshold.
Why does the measured refresh rate differ from my monitor's spec?
The test measures real frames delivered to the browser window. Common reasons for a lower number: the OS display setting is at 60 Hz, the window sits on a lower-Hz screen in a multi-monitor setup, a power-saving mode is throttling, or the browser is capping animation. It measures the screen the window is currently on.
What is backlight bleed and how much is normal?
On the pure-black pattern in a dark room, LCD backlight leaking around edges/corners shows as brighter patches. Almost every LCD has some; it's a defect when clearly visible at normal brightness during dark content. OLED panels show none (each pixel emits its own light).
Does the test work for HDR and wide color gamut?
The info panel detects whether your display and browser advertise HDR (dynamic-range: high) and which gamut is covered (sRGB, Display-P3, Rec.2020). The test patterns themselves are SDR in the MVP — HDR test clips are on the roadmap.