Comments on: Indigo missing

By: Mitchillio

Mitchillio — Sun, 28 Dec 2008 09:31:50 +0000

A good way I learned to remember the colours was “Richard Of York Gave Battle In Vain” which should perhaps now be “Richard Of York Gave Battle Vainly”.

By: ErickB

ErickB — Thu, 25 Dec 2008 06:50:48 +0000

soooo… I can have 1 ‘color’ between 400 & 465nm but 2 colors between 465 & 487?

By: Kittymama

Kittymama — Thu, 25 Dec 2008 05:37:26 +0000

I realized the other day that one shouldn’t need a mnemonic in the first place if one is at all familiar with color to begin with — e.g., of course orange falls betwen red and yellow.

By: David Bradley

David Bradley — Tue, 18 Dec 2007 14:21:23 +0000

Interesting information George. And, I suppose whether or indigo exists is quite subjective. Scientifically, in one sense, it most certainly does not. NIST defines 400-465 nm as violet and 465-482 nm as blue. Nothing in between.

By: George Girod

George Girod — Tue, 18 Dec 2007 14:18:50 +0000

The color does exist, wavelength 435 nm between blue and violet. With its namesake in Indigo dye it would seem that at one point humanity chose to distinguish between the color of the flowers violet and indigo.

The color chart in the Wikipedia article shows the colors blue, violet, and indigo and there is definitely a discernible difference between them. Interestingly enough, indigo was also the color for the untouchable caste in India so discrimination of the color in all possible senses of the word was obvious.

From Wikipedia: One can see spectral indigo by looking at the reflection of a fluorescent tube in a non-recordable compact disc. This works because the CD functions as a diffraction grating, and a fluorescent lamp generally has a peak at 435.833 nm (from mercury), as is visible on the fluorescent lamp spectrum. Also from Wikipedia: “It is impossible to represent spectrum indigo exactly on a computer screen, because true spectrum indigo is outside the color triangle or gamut of the RGB color space defined by the monitor primaries.” This could lead one to question whether we are discarding indigo because it does not reproduce well in our chosen approximations to reality or whether Newton and the population of India are wrong in seeing a color others deny.

As usual, your articles lead one on interesting paths of thought.

George Girod by email

By: David Bradley

David Bradley — Mon, 12 Nov 2007 15:07:22 +0000

Yeah, but that’s the point, there is *no* indigo, according to various studies…so you’re left with ROY G. BI. My mother trained as an eye nurse and the mnemonic she and her colleagues were taught gave the colours in reverse to what one usually sees – VIB GYOR – it never struck me as much of a mnemonic, but I must say I haven’t forgotten it. Of course, it will have to be revised now to IB GYOR.

By: George Girod

George Girod — Mon, 12 Nov 2007 13:00:22 +0000

I am not sure where the song came from but ROY G. BIV is a great way to remember the colors. Red Orange Yellow Green Blue Indigo Violet