[Tig] Why Whites May Not Match note posted to TIG Wiki.

Richard Kirk richard at filmlight.ltd.uk
Thu Feb 2 10:08:14 GMT 2012

Jim Houston <jdhouston at earthlink.net> wrote...

> On Jan 29, 2012, at 5:58 PM, Rob Lingelbach wrote:
>> "D65 white has a spectral definition: it was based on the spectrum of noonday sun at Rochester."
> Sometimes stories develop that come through the same route as Urban Legends...
> something we somehow would like to believe is true, but is not really.
> An accurate description of where all of the "D" colors come from can be found
>  on page 7 of Wyszecki and Stiles (1982), the bible for early color research.
Curses! Unmasked!!

This is one of the many corners I cut in the argument to try and keep it 
I had a look in my copy of Wyszeki & Stiles. It was sort-of based on 
daylight in
Rochester (and a lot of other places too). My basic argument was that we 
do not
actually compare our monitor whites to a true D65 spectrum, and if we 
did they
might not match; and this becomes a bit easier to grasp if we can talk 
of a D65
light as a real thing.

In case anyone is puzzled by this...

If you have a D65 light, it has probably been balanced to give the same XYZ
as D65. If you have got a good one it will probably approximate to the D65
spectrum. However, a real lamp will never quite fit the D65 spectrum, which
is a very wiggly line.

If I have time, I might add this to the Wiki later.

PS: You know your are a colorist when you can spell 'Wyszeki' without 
PPS: Crow tastes ok. You need lots of ketchup, though.

Richard Kirk

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