Where are neon and fluorescent colors on the color spectrum?

This has probably been asked before, but I don’t have search abilities, so I was wondering: where are neons and fluorescent colors on the color spectrum?

All over it. Literally. Neon and fluorescent colors in general are dyes or pigments with a base color, and also the addition of fluorescent dyes which fluoresce under visible light, re-emitting it and making the color more bright and vibrant. Under sunlight, sometimes the fluorescent dyes break down, leaving only the base color.

So basically, typical pigments absorb some of the spectrum, turning it into heat, and reflect the rest. Flourescent dyes absorb part of the spectrum and re-emit it at a specific wavelength, essentially putting off more of a specific colour than what is in the light being shined on it.

I think they’re asking where the color represented by really bright fluorescent colors lies.

It’s true that such colors are often the result of several discrete spectral lines, and so can’t be said to lie anywhere on a spectrum. But the range of colors visible to the human eye can be represented on a Chromaticity Diagram (see here, for instance: http://www.yorku.ca/eye/ciediag1.htm Or Google it yourself under CIE Chromaticity). This sorta-triangular shape contains all the colors the eye can see, including white, which isn’t on the spectrum, either. You can find CIE chromaticity coordinates for all colors, even ultrabright “Day Glo” colors. You just have to realize that the two-dimensional CIE diagram factors out the intensity, which would give a really high response.
Note that, with any two colors, you can make any point on a line joining those two. With any three colors, you can create any color lying within the triangle made by those three coordinates. In other words, your color monitor, which has three color phosphors, can cover quite a bit of the space contained within the CIE locus, but it can’t really hit all the colors of the spectrum.

There’s a lot more to color theory tha this, of course, but this should give you a taste. Ask me about Land’s Retinex theory of color sometime.

Perhaps ‘different wavelength’ (or ‘longer wavelength’, since there is always a loss of energy in fluorescence) is more accurate than ‘specific wavelength’. Fluorescent emission spectra, like absorption spectra, show broad curves with a maximum at a specific wavelength, rather than sharp lines. I don’t recall the quantum mechanical details for this, but it’s not like fluorescent materials absorb light from a broad range of the spectrum and emit at a specific wavelength.

The main difference is that fluorescent materials act as a weak light source of sorts; they change the wavelength of light that impinges on the material and emit it at a different region of the spectrum. (Often, the incident light is ultraviolet, but the emitted light is visible.) Non-fluorescent materials simply reflect photons without changing their wavelength. This also means that the appearance of a non-fluorescent object can vary depending on the composition of the incident light, but a fluorescent object will always fluoresce at the same wavelengths provided it receives incident light of the correct absorption wavelengths. (Its perceived appearance may change depending on the surroundings, though.)

What’s up with Land’s Retinex theory of color? :smiley: