I have a red green c/blind thing.
In order for me to see what normal people see what if...:
I look at an Isihara disc on a computer screen. I see no number. Normal vision shows (say) 6.
The hues of the disc that I cant see are increased in intensity until I can see the 6.
The intensity change readings are applied to photographs on the screen.
I then see what normal vision sees.
regards...Mk