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Analyze the color proportions in your images.

Ishihara's Tests for Colour Deficiency

Authentic and accurate images of Ishihara's test plates

Just because it's black in the dark,
Oh, doesn't mean there's no colors.
— Laleh (Colors)

Authentic and color-accurate images of Ishihara's test plates for colour deficiency.

I provide high-resolution bitmaps and SVG files for each plate. I also provide the position, size, and color of each circle on each test plate.

Can this information be used to make fakes? Yes, but at least they'll be really good ones. Also, please don't.

If you're interested to learn more about colorblindess and the mathematics behind it, see my Designing for Color Blindness, Palettes for Color Blindness and Math of Color Blindness.

And turn those lines of confusion into understanding!

The Ishihara's Tests for Colour Deficiency is a book that comprises 38 so-called "test plates". Each test plate shows a pattern (a digit or a path) that is perceived differently by people who are colorblind than by those with normal vision.

Older versions of the book contained fewer plates (10, 14, and 24).

There are several types of plates: demonstration (first plate, visible by everyone), vanishing (colorblind individuals see no pattern), transformation (colorblind individuals see a different pattern), hidden (only colorblind individuals see the pattern), diagnostic (used to determine the severity and type of colorblindness).

The plates are square (12 cm × 12 cm). The circles of dots are 9 cm in diameter.

One day, I found myself wanting to know what the actual colors were on the Ishihara test plates.

After buying a fake book from Amazon (noob move), I realized that the only way to figure out what the colors were was to photograph each plate from an authentic book. And go down the color correction rabbit hole.

However, at the time, I didn't have my own book. But, luckily the Vancouver Public Library had a 2007 issue of the 38 plate Ishihara book at the central branch. Thank you library!

▲ The 24-color Gretag-Macbeth colorchecker and Ishihara's Tests for Color Deficiency 38 plate book opened to the mysterious hidden plates. This is a snapshot taken with my phone — colors are not accurate but, yes, that is the carpet at the library.

I photographed the plates myself because I could not find correctly exposed and color-corrected images of the plates anywhere online.

There are many images of the Ishihara test plates floating around (16 plate set and 38 plate set, but none show accurate colors. They are generally oversaturated and too dark.

The colors on the actual plates are quite light and pastelly — most available images of these plates do not get this aspect right.

For example, there are subtle differences between hues in plates 6–9 and plates 14–17. The colors in the latter group are a little darker and more saturated. I demonstrate this below with images of plates 6 and 14.

▲ Plate 6 from the 38-set Ishihara test plates.

▲ Plate 14 from the 38-set Ishihara test plates. The background circle colors in plates 14–17 are a little darker and more saturated than those in plates 6–9.

I provide details of the color correction process that I used to create images of the plates that were as close to how they appear in real life.

Any minor differences in background color between plates is due to variation in the paper of the original plates and the effect of the aging process over 13 years.

Note that the backround of the plates is not pure RGB white — this is intentional and a consequence of the color correction process. The background has a luminance of about `L = 95`, slightly darker than the brightest grey colorchecker patch, which has `L = 96.5`.

But you didn't just come here for the images. You want to know the position, size, and color of each circle on each test plate.

There are 25,090 circles across all 38 plates. The number of circles on each plate is: 1 (588), 2 (735), 3 (676), 4 (655), 5 (672), 6 (744), 7 (660), 8 (782), 9 (721), 10 (758), 11 (724), 12 (542), 13 (579), 14 (771), 15 (723), 16 (593), 17 (586), 18 (735), 19 (594), 20 (607), 21 (570), 22 (734), 23 (714), 24 (636), 25 (603), 26 (661), 27 (650), 28 (667), 29 (688), 30 (720), 31 (592), 32 (725), 33 (581), 34 (623), 35 (638), 36 (648), 37 (616), and 38 (579).

I provide a file with the position, size, and color of each circle on each plate in the downloads section.

# plate x y radius R G B
1 1313 835 53 253.06855718292303 138.0174509192895 82.55936428794017
1 1554 1543 53 254.0174509192895 134.86631349330008 80.13804923652228
1 1558 1172 53 253.7310688688065 135.0819569959489 80.92489872234341
1 1659 753 53 253.2848239326893 135.6849485821128 81.9164848862574
1 1667 1507 53 253.87815518853225 134.71019009037082 80.34340916173262
1 1722 904 53 253.27454035525085 136.30850732315363 81.9460891243378
...