What this tool does
This tool displays a series of standard display calibration patterns directly in your browser. Each pattern is designed to reveal a specific characteristic of your monitor: color accuracy, contrast ratio, dead pixels, sharpness, and gradient rendering.
You do not need to install any software or connect special hardware. Everything runs in your browser using a high-resolution canvas element that fills the display area. For the most accurate results, click the Fullscreen button to eliminate browser chrome and other ambient UI elements from your field of view.
The patterns available are:
- **Color Bars** — The classic SMPTE-style bars show pure and combination colors side by side. A well-calibrated screen shows each bar as clearly distinct with no color bleeding between them. - **Gradient** — A smooth black-to-white ramp reveals banding artifacts. Ideally you should see a perfectly smooth transition with no visible steps. - **Contrast** — A near-black and near-white checkerboard tests whether your monitor can distinguish tones near the extremes of its range. - **RGB** — Six color panels covering pure red, green, blue, red-green, green-blue, and red-blue combinations. Use this to check for color tint or channel imbalance. - **Sharpness** — Alternating single-pixel black and white lines. A sharp display renders these as distinct; a soft or anti-aliased display blurs them together. - **White** — A solid white field for spotting stuck dark or dead pixels that appear as dark dots. - **Black** — A solid black field for spotting stuck bright pixels that appear as colored or white dots.
How to use
1. Select a test pattern using the segmented control or dropdown selector. 2. Read the description beneath the selector to understand what to look for. 3. Click the Fullscreen button to expand the pattern to your full screen. 4. Sit at your normal viewing distance and inspect the display. 5. Press Escape or click Exit Fullscreen when finished with that pattern. 6. Move on to the next pattern and repeat.
For the dead pixel tests (White and Black), give your eyes a moment to adjust. A dead pixel appears as a dot that does not change color when the rest of the screen changes.
Understanding the patterns
**Color Bars** are the standard reference used in broadcast television since the 1970s. The eight bars run from white through the primary and secondary additive colors to black. If any bar looks muddy, blended, or has the wrong hue, your monitor's color profile may need adjustment.
**Gradient banding** is a common issue on lower-quality panels and is especially visible on 6-bit displays using dithering to simulate 8-bit color. If you see distinct steps or stripes in the gradient pattern, your panel may have limited bit depth or your display driver may have incorrect gamma settings.
**Contrast** tests evaluate how well your display handles the dark and bright extremes simultaneously. High-contrast monitors show a crisp difference between the near-black and near-white tiles. If the dark tiles look identical to black or the light tiles look identical to white, you may have brightness or contrast settings that are too extreme.
**Sharpness** patterns are sensitive to display scaling. If your operating system is set to a non-integer scaling factor (for example 150% on a Windows HiDPI display), the pixel-level alternating lines will appear grey rather than sharp black and white. This is normal at fractional scaling — it reflects the OS's scaling interpolation, not a display defect.
FAQs
Q: Do I need to calibrate my monitor before using this tool? A: No. This tool is itself a calibration aid. Use it to determine whether calibration is needed or to verify the results after adjustment.
Q: Why does the sharpness pattern look grey instead of black and white? A: This happens when your OS display scaling is set to a fractional percentage such as 125% or 150%. At those settings the OS must interpolate pixels, blending adjacent black and white lines into grey. Try setting scaling to 100% or 200% for a true pixel-level result.
Q: What is a dead pixel versus a stuck pixel? A: A dead pixel is permanently off and appears as a black dot regardless of what is displayed. A stuck pixel is permanently on and appears as a colored or white dot. Dead pixels are most visible on the White pattern; stuck pixels are most visible on the Black pattern.
Q: Can I use this on a TV or external display? A: Yes. Open this page in a browser on any device connected to the display you want to test and click Fullscreen.
Q: Is any data sent to a server when I use this tool? A: No. All pattern rendering happens locally in your browser using the HTML5 Canvas API. Nothing is transmitted.
Q: What brightness and contrast settings should I use while testing? A: Set your monitor to its factory default or sRGB preset before running these tests. Testing with unusual brightness or contrast settings may make a correctly calibrated display appear miscalibrated.
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