[sooty]

When I was little, at school we had a colour blind test every year for a few years.

That Ishihara's one, ( I did not know his name until Showson mentioned it).
We were given 5~6 pages and had to read numbers.
Among them I could not identify anything number or any shape.
It was specially made for a colour blind person and if anybody managed to be able to read it, the person was a colour blind. (I did not know it then)

(Also we had a blood test so that everybody knew what type-group we were. I am a blood type A.)