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RE: Colour Vision



Adrian Thomas wrote:-
>>Ishihara takes the form of a book with with coloured numbers printed on
speckled coloured backgrounds<< 

Not sure what printers inks are used to make the Ishihara tests, but
most of these colour blindness tests work on the basis of metameric
matching. In other words a particular red and a particular green
together appear as yellow, which can also be produced with a single
yellow patch, or with a different red and a different green. Under
different lighting, shot on different film or with different (abnormal)
vision, matched colours can appear different, or vice versa.

Since monitors are all about producing a colour gamut with just three
specific coloured phosphors, (which is, in itself, a form of metameric
matching)  I'd have thought that only a test based on colours produced
with those specific phosphors would be totally reliable.

That is, until someone develops a Farnsworth-Munsell 100-hue monitor
:-)

Notwithstanding the above, has anyone tried scanning the Ishihara tests,
displaying them on a monitor, and seeing how known colour blind subjects
and others score?

No questions about the colour response of the scanner please!

-=+=-=+=-=+=-
  Dominic Case
  Atlab Australia
-=+=-=+=-=+=-


---
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