Free Grey-Green Colour Blindness Test Online

This Grey-Green Color Blindness Test is an Ishihara-style screening that estimates how well you can detect green numerals embedded in near-neutral grey dot fields. It suits users who notice confusion between grey and green in maps, UIs, textiles, or charts; students in vision science; and anyone curious about color perception. It has an adaptive difficulty, reports accuracy, timing, and gives scientific conclusions.

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How to use the test

• Prepare the display: disable night mode, blue-light filters, HDR, and any color boosts; use neutral room lighting.
• Viewing: sit at a comfortable distance with the screen centered and steady.
• Run: start the green gray color blind test and inspect each plate.
• Respond: type the number you see (1-99) and submit, or choose Skip if none is visible.
• Adaptation: correct answers increase challenge; errors or skips reduce it.
• Results: review total score, highest difficulty reached, average or median response time, and a short interpretation.
• Interpretation guide: consistent success at higher levels suggests typical grey-green discrimination; difficulty at easier levels may suggest a deficit and warrants clinical testing.

Features of the test

• Plates and rendering: 20 procedurally generated Ishihara-like circles per run; numerals use a green hue band while backgrounds are near-neutral greys with matched lightness to limit luminance cues.
• Input and feedback: integer input (1-99), Submit and Skip, with instant “Correct,” “Incorrect” (reveals target), or “Skipped.”
• Adaptive difficulty: a continuous difficulty variable mapped to seven labels (Very Easy → Extreme). Correct streaks raise difficulty; mistakes lower it.
• Extreme refinement: at the top tier the engine applies small hue-difference and saturation micro-steps to probe thresholds.
• Dot layout realism: randomized dot grids, multi-size tiling, overlap limits, and non-numeric micro-shapes outside the numeral mask to reduce edge artifacts.
• Timing metrics: per-plate timers plus median/average summaries; brief input lock between plates prevents double submissions.
• Scoring and analytics:
  • Score n/20 and accuracy %.
  • Per-level table (attempts, correct, accuracy for levels 1-7).
  • Mastery metric (weighted accuracy across difficulty levels).
  • Threshold proxy: smallest successfully resolved scaled hue separation (Δh).
  • Headline category: Excellent / Good / Mildly reduced / Moderately reduced / Markedly reduced based on the threshold proxy.
• Operation summary: the engine reduces chromatic separation between green numerals and grey backgrounds across levels while holding lightness near parity; results reflect your ability to use chromatic, not luminance, cues.

Grey-green plate with number 25 on it (Ishihara-style)

Understanding Grey-Green Vision and Its Impact

Grey-green confusion is not a classic category like red-green or blue-yellow, but it still matters in practice. Many users struggle with green signals placed on low-chroma grey backgrounds, especially in maps, dashboards, or user interfaces where subtle hues carry meaning.

Clinical background

• Red-green pathways: Most inherited deficiencies are protan (red) or deutan (green). Grey-green confusion can be a side effect of reduced green sensitivity.
• Acquired causes: Cataract, macular degeneration, glaucoma, diabetic retinopathy, optic neuropathies, or even medications can shift color sensitivity.
• Testing standards: Clinical tools include the Farnsworth D-15 and desaturated D-15 arrangement tests, plus automated hue-discrimination tasks.

Display and environment factors

Online grey-green tests depend on your screen:

• Calibrated displays and neutral lighting improve reliability.
• Night mode, HDR, or color filters distort results.
• Lightness control is key-if green and grey differ in brightness, luminance cues can hide real deficits.

Practical impact

• Design and accessibility: Green text or icons on grey backgrounds may be hard to spot.
• Safety and navigation: Maps, aviation displays, or transport systems often use green signals against neutral tones.
• Everyday life: Choosing fabrics (e.g., grey vs olive), reading graphs, or spotting alerts in software.

What to do if issues persist

• Repeat the test under daylight-like lighting on another display.
• Use redundant cues (shapes, labels, motion) in design.
• Seek formal testing if reduced grey-green sensitivity persists.

FAQ

1. Is this diagnostic? – No. It is a screening tool. Only a clinical exam can diagnose a color vision deficiency.
2. What does a low Δh threshold mean? – You could resolve very small hue separations, indicating stronger grey-green discrimination.
3. Can lighting or screens affect results? – Yes. Ambient light, display calibration, and filters can shift apparent difficulty.
4. Is grey-green loss the same as deutan or protan? – Not necessarily. Deutan/protan (red-green) anomalies are common; this test specifically probes green on low-chroma grey, which can reveal different usability issues.
5. Can training fix color blindness? – No established training restores congenital deficits. Accessibility tactics and better palettes can mitigate impact.
6. Who should try this? – Anyone who struggles to spot green indicators on grey UIs, maps, or charts, or who needs a quick self-check before formal testing.
7. What if my results are poor? – Re-test under neutral lighting on another display. If difficulty persists, seek a clinical deuteranomaly test or protanopia test as appropriate.

Sources and references

• American Academy of Ophthalmology – How Color Blindness Is Tested
• NCBI Bookshelf – Classification of Color Vision Defects
• Wikipedia – Color vision test

What are your results? Would you like to see any features in the test? Let us know in the comments below!

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