You're a bright lad BobT.
Very well put indeed.
If we want to talk a colour's frequency we need to consider the brightness because the brighter it gets the more frequencies we're getting in the mix.
I guess white light is the best example of how visible light is a MIXTURE of wavelengths.
Bob Talbot <BobTalbot@xxxxxxxxxxxxxxxxxxx> wrote:
Bob Talbot <BobTalbot@xxxxxxxxxxxxxxxxxxx> wrote:
> Actually, it is all included in the spectrum. Light is just one
component of a long and continuous spectrum that includes radio,
light, beta, gamma, and other waves. Being a ham makes the entire
spectrum very real.
>
> All that changes is the frequency.
Bob
- Radiometrically you are correct.
- Photometrically you are IMO missing the point.
Radiometrically we can measure the wavelength, amplitude, phase,
direction, constancy etc of electromagnetic radiation whether it be
light, UV, IR by means of it's physical properties (strictly
interactions) with other physical things.
What we cannot do is actually measure what it looks like.
"Pure" monochromatic wavelengths of light (by definition light being
the part of the electromagnetic spectrum we can see) are generally
seen as coloured (though not the same by everybody - consider
synaesthesia. :) ... so there is a one-way relationship. But exactly
the same colour ( a perceptual thing ) can be experienced by looking
at a mixture of wavelengths, so you simply cannot make the reverse
association.
Oh let's quote someone else ... the "Color - Enpsychlopedia"
http://psychcentral.com/psypsych/Color
"Electromagnetic radiation is a mixture of radiation of different
wavelengths and intensities. When this radiation has a wavelength
inside the human visibility range (approximately from 380 nm to 740
nm), it is called light. The light's spectrum records each
wavelength's intensity. The full spectrum of the incoming radiation
from an object determines the visual appearance of that object,
including its perceived color. As we will see, there are many more
spectra than color sensations; in fact one may formally define a color
to be the whole class of spectra which give rise to the same color
sensation, although any such definition would vary widely among
different species and also somewhat among individuals
intraspecifically."
Colour (as we see it) also is an anomalous beast when it comes to
intensity.
1) A mixture of wavelengths that looks bright yellow when viewed at
high intensity looks olive green when less intense. Exactly the same
mixture of wavelengths - the only physical difference is the total
amplitude. The "standard observer" charts attempt to address this but
currently only at two points: photopic and scotopic. The "real world"
is everything in between as well ...
2) How many colours do you see ? ( Not including white ! )
http://homepage.ntlworld.com/patrick.davies/odd4.htm
Explain that with simple physics ...
BobT
Herschel Mair
Head of the Department of Photography,
Head of the Department of Photography,
Higher College of Technology
Muscat
Sultanate of Oman
Muscat
Sultanate of Oman
Adobe Certified instructor
+ (986) 99899 673
__________________________________________________
Do You Yahoo!?
Tired of spam? Yahoo! Mail has the best spam protection around
http://mail.yahoo.com
