Re: Metamerism
Re: Metamerism
- Subject: Re: Metamerism
- From: neil snape <email@hidden>
- Date: Wed, 31 Oct 2001 10:28:56 +0100
on 31/10/2001 08:48, Igor Asselbergs at email@hidden wrote:
>
Grant Symon wrote:
>
> As a photographer I've always lived with metamerism....as has everyone else
>
> in the world. In everyday life nobody pays the least bit of attention to the
>
> phenomenon. No one, when looking at a movie, notices that the relationship
>
> between two colours changes when the source light changes temperature
>
In this case either the bulb in the projector or the light used when
>
shooting the movie might be regarded as source light. Either way, or both
>
ways, it's not metamerism we're dealing with but colour constancy.
Yes.
>
"However, in color science, color is considered as a perceptual rather than
>
a physical property of objects."
Yes 2.
>
> and
>
> yet....their relationship does change.
>
Normally, the relationship between the colours hardly changes. It's the
>
colours as a whole that change. For instance, all colours become more
>
blueish or more reddish under different lighting. And this change as a whole
>
is not perceived, being a result of colour constancy.
Yes 3, but we're getting a bit far from the original post that was as much
about grey shifting non proportionally depending on the viewing light.
>
Once we were testing software when some some parts of a picture, displayed
>
by the software, had a strong reddish hue about them. For days we searched
>
in vain for the bug causing this trouble. In the end it appeared we had
>
searched in the wrong direction: It was the picture as a whole that had gone
>
greenish, with the exclusion of some parts that didn't 'really' change but
>
now appeared reddish as a result of colour constancy.
Yes4.
Ah to quote a cookbook maker "it's not about how good the individual
ingredients are but how good the soup (as a whole) tastes."
Neil Snape email@hidden
http://mapage.noos.fr/nsnape