Ishihara Colorblind Test Generator
Take an interactive colorblind test, or generate custom Ishihara pseudo-isochromatic dot plates with your own text, numbers, or secret messages.
Identify the Hidden Content
Look carefully at the dot pattern. Select what you see inside the plate:
Custom Ishihara Plate Maker
Generate custom pseudo-isochromatic dot plates with your own text, numbers, or secret messages.
Send the downloaded plate to friends or colleagues. People with normal vision can easily decode the secret text, while colorblind vision filters obscure the silhouette.
Ishihara plates use dot patterns with contrasting hues (e.g. Red/Orange vs. Green/Olive). Viewers with normal trichromatic vision easily separate the colors to read the hidden digits. Individuals with red-green colorblindness (Deuteranopia / Protanopia / Daltonism) perceive both hue groups as identical yellowish-brown tones.
How to Create and Test Custom Ishihara Plates
Generate, customize, and evaluate pseudo-isochromatic dot plates in 3 quick steps.
Select Test or Custom Maker Mode
Practice with randomized interactive color vision quizzes, or switch to Custom Plate Maker to encode any secret word, number, or shape.
Apply Real-Time CVD Vision Filters
Toggle Deuteranopia, Protanopia, Tritanopia, and Monochromacy filters underneath the plate canvas to verify how the numbers dissolve.
Export High-Resolution PNGs
Download full-resolution dot plates for ophthalmology study, classroom presentations, academic papers, or design audits.
Understanding Ishihara Color Vision Testing & Daltonism
Learn how pseudo-isochromatic plates screen for colorblindness and how clinical tests differ from online tools.
Pseudo-Isochromatic Technology
Invented by Dr. Shinobu Ishihara at the University of Tokyo in 1917, the test uses pseudo-isochromatic plates containing randomized dot sizes. People with normal trichromatic vision separate contrasting warm hues (red/orange) from background cool hues (green/olive) to identify the hidden figures.
Conditions Screened
The test primarily screens for Red-Green Color Blindness (Daltonism, affecting 8% of males):
• Deuteranopia / Deuteranomaly: Green photoreceptor cone deficiency.
• Protanopia / Protanomaly: Red photoreceptor cone deficiency.
• Tritanopia: Blue-yellow deficiency (rare, <0.01% of population).
Online vs. Clinical Testing
Online tests offer instant self-screening and educational visualization. However, monitor brightness, sRGB color calibration, and room lighting can affect perceived contrast. For official medical certifications (e.g. aviation, maritime, or commercial driving licenses), consult a licensed ophthalmologist.
FAQ
Frequently asked questions about Ishihara colorblind testing, custom plate generation, and color vision.
What is an Ishihara Colorblind Test?
Invented in 1917 by Dr. Shinobu Ishihara, the Ishihara test is the global standard for detecting red-green color vision deficiency. It features circular plates filled with randomized colored dots that form hidden numbers, letters, or geometric paths visible only to people with specific cone responses.
How does the Custom Plate Maker work?
Our custom plate maker takes your input (such as numbers like "74", letters, or geometric shapes), renders a virtual high-contrast mask in an offscreen HTML5 canvas, and samples thousands of non-overlapping circles using spatial hash collision detection to reconstruct your silhouette with authentic Ishihara color palettes.
Why do hidden numbers disappear under colorblind vision?
Red-green color blindness merges red, orange, green, and olive hues into identical yellowish-brown shades. When the chromatic difference between the foreground number and the background dots collapses, the pattern becomes indistinguishable from surrounding noise.
Can I download the generated dot plates for commercial or academic use?
Yes! All generated PNG plates are rendered 100% locally in your browser sandbox and can be freely downloaded for research papers, design portfolios, medical lectures, or accessibility presentations.