> michael writes (in blue) ... >> >> ...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).
Yes, I have always known this about flowers, and is why it is often reccommended to photograph them in twilight under an open clear sky. Of course flowers are such wonderful things that they photograph well in any light - even moonlight. >> 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). Well, you have just described the reality of working with an analog animal in a digital cage - who would be a lion tamer. If I get an out-o-gamut warning in PS CMYK preview then I print a test print out anyway, as out-o-gamut colours - are in fact genuine colours, and can often intereact with in-o-gamut colours in a way that makes a picture more interesting to the eye. Which makes working in Adobe RGB on a monitor precisely that - a monitor, and so it pays to think out of the "box". > 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. Is that deep blue? (yes it is!) - then a Wratten 47B is a truly wondrous thing to look at. all the best William Curwen =============================================================== GO TO http://www.prodig.org for ~ GUIDELINES ~ un/SUBSCRIBING ~ ITEMS for SALE
