Desperado: A very color blind friend took to sewing small buttons or knots of thread on shirt tails and pants pockets to identify the color. I forget his system but it was something like one button for black; two for brown, three for blue. He also had notched cut into the insole for shoes, little yarn streamers sewed into the toes of his socks.

He was really quite, exceptionally, color blind. Most have problems determining green from red or other narrow differences. For him everything was, according to him, black, white or gray. He couldn't tell day-glow orange from tan.

Another trick is to use color cards and comparing them against the object. The military has had issues with electrical maintenance personnel reading color codes under low-level red, now blue/green, light or other difficult light conditions.