Re: visible spectrum?
Re: visible spectrum?
- Subject: Re: visible spectrum?
- From: Phil Green <email@hidden>
- Date: Sun, 13 Jan 2002 13:03:51 +0000
- Organization: LCP
Stefan Fiedler wrote:
>
>
I find 2 different theories for the visible spectrum: one says 380 -
>
680 Nanometers the other says 380 - 780 nm. What is correct?
The reason why you can get different answers to this question is that
the sensitivity of the visual system falls off to nothing at the ends of
the range. So there are broad regions at the edges of the visible
spectrum where the arrival of photons can trigger a response, but in
practice it makes no significant contribution to perception. So the
answer you choose depends on the application. For practical colour
measurement purposes, as long as the range 400-700 is included the
effect of different end points to the range is negligible. In ISO 13655,
360-780 is preferred but 400-700 is acceptable.
--
Phil Green
Colour Imaging Group
School of Printing and Publishing
LCP
Elephant and Castle, London SE1 6SB
Tel: +44 020 7514 6759 Fax: +44 020 7514 6772
http://www.digitalcolour.org