Tweet of the Day

This is a reverse Ishihara test, where the number is only visible to people who *are* colorblind.

Everyone who said "lol I know this isn't a number, you're just messing with me": congrats! You're not colorblind. :) https://t.co/81bOuMSfXs

— Isaac King 🔍 (@IsaacKing314) May 28, 2024

Protanopia and deuteranopia are two specific kinds of color blindness that makes it hard to distinguish red and green. No doubt you've seen a lot of these "colorblindness tests" on the internet, taken from the Ishihara test. Most of the images you've seen from the test are easy to decipher if you see a full range of colors. Plate #19 looks like a mishmash of colored dots to most people. If you have deuteranopia, you are liable to see the number 73. If you have protanopia, you are more likely to see the number 23. Check out how others see this glob of colored dots, including some manipulations of the original image that shed more light on what you are seeing. (Thanks, gwdMaine!)