Thread View: sci.misc
3 messages
3 total messages
Started by jk3k+
Mon, 07 Dec 1987 10:46
Re: Color
Author: jk3k+
Date: Mon, 07 Dec 1987 10:46
Date: Mon, 07 Dec 1987 10:46
10 lines
1135 bytes
1135 bytes
Some more information about color perception: When you add two colors of light, you get something that looks in-between but less pure. So if i show you a mixture of yellow and blue light, it will indeed look green. Then if show you monochromatic green light, it will look more green. Thus with any finite set of colors, you can't generate all the others, although you can get pretty close. The exception to this is purple, which, as pointed out before, is really only a mixture of red and violet. So if you mix together red and violet lights, you get something which is _really_ purple. --Joe
Re: Color
Author: Wayne A. Throop
Date: Tue, 08 Dec 1987 18:30
Date: Tue, 08 Dec 1987 18:30
26 lines
1621 bytes
1621 bytes
> jk3k+@andrew.cmu.edu (Joseph G. Keane)
> Some more information about color perception: When you add two colors of
> light, you get something that looks in-between but less pure.
Simply not true, as Joseph's own example of "purple" shows. Adding red and
violet doesn't give a yellowish-green as you might expect, but purple.
Again, the above claim is simply not true in general.
> So if i show
> you a mixture of yellow and blue light, it will indeed look green. Then if
> show you monochromatic green light, it will look more green.
I take it you haven't actually tried this. If you mix yellow and blue
*light*, you normally get something very like white. (This depends
strongly on the exact spectrums (spectra? whatever) and intensity of
"yellow" and "blue" used of course.)
Now, granted, yellow and blue *pigments*, when mixed, normally yield a
green *pigment*, but that's a horse of a... well, it's a different
kettle of fish, anyhow.
--
"Trust me. I know what I'm doing."
--- Sledge Hammer
--
Wayne Throop <the-known-world>!mcnc!rti!xyzzy!throopw
Re: Color
Author: William Calvin
Date: Wed, 09 Dec 1987 07:51
Date: Wed, 09 Dec 1987 07:51
12 lines
989 bytes
989 bytes
Color hues are basically a function of the relative activity in two cone types, e.g., the ratio of "red" cone to "green" cone activity gives yellows whether it is accomplished by a 540 nm pure wavelength or a mixture of 500 and 600. But red and blue cone absorbance curves don't overlap enough so as to produce some ratios with any single wavelength stimulus. The ratios produced by a 400 and 700 nm mixture are not unique but they cannot be matched by a single wavelength. We call it purple. William H. Calvin University of Washington NJ-15, Seattle WA 98195 wcalvin@well.uucp 206/328-1192
Thread Navigation
This is a paginated view of messages in the thread with full content displayed inline.
Messages are displayed in chronological order, with the original post highlighted in green.
Use pagination controls to navigate through all messages in large threads.
Back to All Threads