Mark Roberts wrote: > Ann Sanfedele <[EMAIL PROTECTED]> wrote: > > >Wow - thanks Mark - that never occured to me... > >I don't see anything very wonky witht he stuff from my 820 I will say. > > Theoretically, all RGB (or CMYK) images will exhibit metamerism to > *some* extent - it's the nature of the beast - but in most cases it's so > incredibly slight it isn't noticeable. "Metamers" are two colors > (sources of light, to be strictly accurate) that *look* the same to the > human eye or other RGB sensor but really *aren't* the same. For example, > if combine a red and a green light to make yellow they'll appear the > same as a single yellow light source to your eye and to film. But > interposing a blue filter exposes the two "yellows" as metamers: The > single yellow light source will be attenuated (dimmed) much more then > the red/blue light source that looks like the same color. > > Look at it this way: Yellow light has a wavelength around 575 nm. > Combining red (650 nm) and green (500 nm) *doesn't* produce light of 575 > nm wavelength - you just have two separate wavelengths present at the > same time - but it'll *look* the same as light of 575 nm wavelength to > the human eye. Cool, huh? > > -- > Mark Roberts > Photography and writing > www.robertstech.com
Very cool :) But something puzzles me. This all sounds like things that apply to images on a monitor or stage lighting, for instance, but once you have a hard copy of something, you are dealing with pigment, yes? Given I have a piece of red cloth that is the same color as a piece of matte paper I've printed (and the same reflective um "index") they look the same in the same light to the (same) human eye. umm so the pigments have different reflective qualities that react to light differently? annsan
