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The plates on this site

The plates come from the 12th edition of Shinobu Ishihara's Tests for Colour-Blindness, printed by Kanehara in 1957 and signed by Ishihara. A copy at the Wellcome Collection in London was photographed page by page.

Every plate was checked against an independent modern printing, dot by dot, and, where available, against loose Ishihara plates from 1917–1959. One plate, number 5, was redrawn after 1957; its answers stayed the same.

Checking turned up fakes online: one popular site shows plate 11's dots recolored as plate 3, a “35” drawn on plate 23's dots, and an invented plate 21.

Each plate was then redrawn as a vector image: all 24,470 dots, each with the color measured from the scan. The redrawn plates match the scans to within the scans' own print noise, and behave the same way as the scans under the deutan and protan models.

The 1957 paper has yellowed. Measured against published ink measurements of seven printings, the scanned ink colors are as close to real Ishihara inks as Kanehara's printings are to each other. So the site offers them as scanned, on white paper, and a white-balanced version.

The answers come from Kanehara's own instruction booklet for the 38-plate edition.

Sources

• Kanehara Trading. The Series of Plates Designed as a Test for Colour Deficiency, 38 Plates Edition: instructions (as distributed by Good-Lite).
• Ishihara S. 色盲検査表の話 (1941), Aozora Bunko.
• National Research Council (1981). Procedures for Testing Color Vision. National Academy Press.
• Birch J (1997). Efficiency of the Ishihara test for identifying red-green colour deficiency. Ophthalmic Physiol Opt 17:403–408.
• Birch J (2010). Identification of red-green colour deficiency: sensitivity of the Ishihara and AO HRR plates to identify slight anomalous trichromatism. Ophthalmic Physiol Opt 30:667–671.
• Birch J (2012). Worldwide prevalence of red-green color deficiency. J Opt Soc Am A 29:313–320.
• Miquilini L et al. (2019). A proposed correction in the weighted method to score the Ishihara test. BMC Res Notes.
• Miyahara E (2009). Chromaticity co-ordinates of Ishihara plates reveal that hidden digit plates can be read by S-cones. Clin Exp Optom 92:434–439.
• Somers LP, Bosten JM (2023). Screening for mild anomalous trichromacy using the Ishihara plates test. J Opt Soc Am A 40:A208–A219; ink spectra on OSF.
• Machado GM, Oliveira MM, Fernandes LAF (2009). A physiologically-based model for simulation of color vision deficiency. IEEE TVCG 15:1291–1298.
• Stockman A, Sharpe LT (2000). The spectral sensitivities of the middle- and long-wavelength-sensitive cones derived from measurements in observers of known genotype. Vision Res 40:1711–1737.
• CIE (1951). Scotopic luminous efficiency function (rod vision).
• Wright WD (1952). The characteristics of tritanopia. J Opt Soc Am 42:509.
• Kohl S, Jägle H, Wissinger B, Zobor D. Achromatopsia. GeneReviews, NCBI Bookshelf.
• Japan Ophthalmologists Association. 色覚異常といわれたら.
• Japanese Association of Medical Sciences. Organized color-vision terms (2007).

Credits

The plates: Shinobu Ishihara, Tests for Colour-Blindness, 12th edition, Kanehara, 1957. Redrawn as vectors from the scans of the Wellcome Collection (b18023319), CC BY-NC 4.0. Modifications: redrawn as circles, paper replaced by white, and an optional white balance.

Loose Ishihara plates from 1917–1959: Wellcome Collection, CC BY 4.0.

The book at the Wellcome Collection →