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11FONT RENDERING / 72—9 PX

Online Text Clarity Test

Read black text at nine sizes on white, the same text reversed on black, and coloured text that exposes chroma subsampling when a TV or video chain drops colour resolution.

  • 3 patterns
  • Fullscreen
  • No install

Browser-generated pattern · Not a laboratory measurement

PATTERNS / 03

Patterns in this test

Each pattern targets a different symptom. Start from the top, or jump straight to the one you need.

  1. 01

    Black on white · nine sizes

    Read down to the smallest line at your normal distance. Look for halos, coloured edges and letters that merge.

  2. 02

    White on black · nine sizes

    Light text on dark exposes colour fringing on OLED subpixel layouts. Compare the edges with the black-on-white screen.

  3. 03

    Chroma 4:4:4 check

    Every coloured line should be as readable as the gray one. Blurry red or blue text means the signal drops colour detail.

PROTOCOL / 01—04

How to use this test

Keyboard and touch

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  1. 01

    Clean the screen gently and let it reach its normal operating temperature.

  2. 02

    Set browser zoom to 100% and use the brightness and picture mode you normally use.

  3. 03

    Start fullscreen mode. Each pattern shows a short hint about what to look at.

  4. 04

    Observe from your normal position first, then move closer only to inspect a detail.

OBSERVE

What to look for

  • Clean, stable edges without bright sharpening halos
  • Small letters that remain distinct rather than merging together
  • Coloured text as readable as the gray reference line

INTERPRET

How to read the result

Soft text can come from browser zoom, operating-system scaling or non-native resolution. Coloured fringes on white-on-black text usually come from the subpixel layout (common on WOLED and QD-OLED). If coloured lines blur while black text stays sharp, the signal is likely 4:2:2 or 4:2:0: enable PC mode or full RGB.

LIMITS

Limits of a browser test

Font rasterisation varies by browser and operating system. Use 100% browser zoom and the display’s native resolution; this visual check does not measure optical sharpness.

FAQ

Frequently asked questions

01What is chroma subsampling?

Many TVs and video signals keep full brightness detail but halve colour resolution (4:2:2 or 4:2:0). It is invisible in video but makes thin coloured text blurry. A PC or Game mode with 4:4:4 or full RGB fixes it.

02Why do I see coloured edges around text?

The cause can be chroma subsampling, subpixel rendering, the panel’s pixel structure or excess sharpening. Compare black-on-white with white-on-black and another input before diagnosing the screen.

03Why should browser zoom be set to 100%?

Other zoom levels resample letter shapes and make text look softer or uneven, masking the display’s normal rendering.

NEXT / SCREENPROBE

Continue checking

10

Sharpness & geometry

Check scaling, overscan, lines and one-pixel detail.

↗ 01

Black screen

Pure #000000 with no overlays, compression or glow.

↗ 02

Dead pixel test

Cycle exact solid colours to find dead and stuck subpixels.

↗
FEEDBACK / 01

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