william writes ...

> ...
>
> ...does this mean that L*a*b covers near infra-red and
> near ultra-violet which the human eye can percieve, if not 'see'? It is
> these 'invisible' colours that have a profound influence upon the brightly
> coloured part of the visible spectrum. Think flowers in noonday sunshine.

  UV on flower petals is a different ballgame.  Such phenomena is due to
absorption of UV and re-emmission of color of a different wavelength.  It is
not pure reflectance, as is ink on paper (... although I suppose UV enhanced
papers may be an exception).

> BTW, the visual world is made up of an infinite number of colours - much
> more than the 16 million colours within a 24bit colourspace. ...

  Keep in mind as well ... percieved color cannot be described (modeled) by
a 3-dimensional matrix of choices (a cube, which is RGB), and colors which
are a part of reality are some shape within the "box", with much of the
remainder being wasted RGB options.  I run into this a lot because of trying
to synthesize presentation of scientific imagery.  Such pseudo-coloring
generates much more "out-of-gamut" color than those who work with real world
photography will ever see (and I don't mean "out-of-gamut" with respect to
printing. ... I mean out-of-gamut with respect to the color space I might be
working in).

  You may be correct with respect to some RGB color definitions being
outside of human perception ... it seems I do remember Bruce Fraser saying
there is no such color as 0,0,255, no matter which color space.

cheerios ... shAf  :o)
Avalon Peninsula, Newfoundland
www.micro-investigations.com


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