Digital BW, The Print

* -----Original Message-----
* From: Diane Benedict [mailto:highhopes813@yahoo.com] 
* Sent: Wednesday, December 10, 2003 4:44 AM
* To: DigitalBlackandWhiteThePrint@yahoogroups.com
* Subject: Re: [Digital BW] IP5.6 and metamerism
* 
* 
* --- In DigitalBlackandWhiteThePrint@yahoogroups.com, Tom Baker 
* <tbaker1328@s...> wrote:
* It is my understanding that the different profiles for the different 
* viewing lights are to compensate just for the color of the light.  I 
* beleive that they are not related to metamerism.
* 
* Huh?
* 
* Isn't this what metamerism is all about? The print looks different 
* in different light.

Diane,

Yes and no. Those of us involved in inkjet printing use the term metamerism
but we really are not using it properly.

Metamerism is a condition that exists when comparing TWO color samples that
match under one set of conditions.

A definition:

"Metamerism refers to the situation where two colour samples appear to match
under one condition but not under another; the match is said to be
conditional. Metamerism is usually discussed in terms of two illuminants
(illuminant metamerism) whereby two samples may match under one illuminant
but not under another. Other types of metamerism include geometrical
metamerism and observer metamerism. Two samples that conditionally match are
said to be a metameric pair. If two samples have identical reflectance
spectra then they cannot be metameric - they are an unconditional match."

For a good explanation check out this excellent article:

http://www.mwords.co.uk/pages/FAQ/articleMetamerism.htm

Everything changes color when you change the light source. Under a warm
tungsten light bulb you would expect a print to look warm. I blue daylight
it is going to look cooler, under fluorescent it will sometimes look greener
but that may depend upon the fluorescent tubes being used.

If I say a print has metamerism, I mean that it makes an unexpected change
in color under different light sources. For example if it looks cooler under
warm tungsten light and warm in daylight. This would be a change in an
unexpected color direction. To a lesser degree of metamerism might give you
a print that gets warmer under tungsten or cooler under daylight  but the
change is much stronger than you would expect.

We use the word a lot here but I don't think we all mean exactly the same
thing. The problem is also compounded by the fact that near the neutral
point very slight changes in hue are perceived differently. I think that a
lot of us, including me, do not have perfectly balanced color vision and
that it changes subtly day-to-day and hour-to-hour as you move from one
lighting condition to another.

I hope that helps but I may have made things more confusing.

Martin Wesley
www.carolyn.cc/Guests/MartinWesley/pages/MW_01.html
www.borderless-photos.de/guests.html