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RE: Colour Vision
- To: 'multiple recipients of' <telecine at alegria.com>
- Subject: RE: Colour Vision
- From: Case Dominic <Dominic_Case at atlab.com.au>
- Date: Thu, 19 Feb 1998 14:17:23 +1100
- Resent-Date: Wed, 18 Feb 1998 19:19:36 -0800
- Resent-From: telecine at alegria.com
- Resent-Message-ID: <"FqUwi.A.H2F.WS660" at sun>
- Resent-Sender: telecine-request at alegria.com
- Resent-To: multiple recipients of <telecine at alegria.com>
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!
Thanks to Blake Jones for support of the TIG in 1998.
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