Sunday, February 21, 2010

The Color Wheel, Part 1

How we name and separate the colors on the color wheel is a subject with roots in physical science, visual perception, and artistic tradition. That’s what I’d like to explore over the next seven posts. The color wheel is our mental map of the color universe.

This may seem like boring review, but if you read all the posts this week, you may end up completely rethinking the color wheel—at least that’s what happened to me.

When white light is bent or refracted by a prism or a rainbow, it separates into a continuous gradation of colors. Within that smooth spectrum, there’s no clear division between the colors. Sir Isaac Newton (1642-1727) proposed wrapping the spectral colors around a circle by merging the two ends, red and violet. The result was a hue circle, better known as a color wheel.

Newton observed that the hues gradate smoothly into each other. But in his diagram he identified seven colors we’ve come to know as ROYGBIV (red, orange, yellow, green, blue, indigo, and violet). The tradition among artists has been to drop the indigo and to concentrate on six basic colors.

Tomorrow we’ll look at the colors that Newton and his contemporaries called “primitive” and which we call “primary.”
Reviewing the posts in this series:
Part 1: Wrapping the Spectrum
Part 2: Primaries and Secondaries
Part 3: Complements, Afterimages, and Chroma
Part 4: Problems with the Traditional Wheel
Part 5: The Munsell System
Part 6: Cyan, Magenta, and Yellow
Part 7: The Yurmby Wheel


Björn said...

I really like that you're going back to old school gurney journey art knowledge posts!!

This is gonna be awesome, thanks !!

Johan said...

Indigo must have it's own specifics to be called a hue by Newton?
Why is the Indigo dropped?
Every book on color, painting, etc, talks about 6 colors, while there are 7...

The fearless threader said...

I have to express my eternal gratitude for these practical posts. Thank you for your help in my work!

Everett Patterson said...

Is it scientifically legitimate to merge the colors at either end, forming a circle, as Newton did? Sometimes I hear that the waves after violet proceed out of the visible spectrum into ultraviolet, x-rays and so on,,and that on the other side, red gives way to infrared, microwaves, etc. If this is the case, why is is "okay" to start the visible spectrum over again at a lower frequency?

I know there is such a phenomenon as a double-rainbow in the sky - does this have anything to do with the visible spectrum repeating itself when refracted?

These scientific questions probably don't have much effect on us as artists - after all, I can clearly see that reddish purples blend into purplish reds seamlessly. Still, I'd like to know if there's a more solid principle behind wrapping the spectrum around a circle than simply because it "looks right."

Daniel.Z said...

Looking forward to this series.
Can never have enough of that fundamental knowledge.

Richard said...

It's best to refer to the residence of color as in the "mind". Here's Newton on the subject:
If at any time I speak of Light and Rays as coloured or endued with Colours, I would be understood to speak not philosophically [scientifically] and properly, but grossly, and according to such Conceptions as vulgar [uneducated] People in seeing all these Experiments would be apt to frame. For the Rays to speak properly are not coloured. In them there is nothing else than a certain Power and Disposition to stir up a Sensation of this or that Colour. ... So Colours in the Object are nothing but a Disposition to reflect this or that sort of Rays more copiously than the rest; in the Rays they are nothing but their Dispositions to propagate this or that motion into the Sensorium; and in the Sensorium they are Sensations of those Motions under the Forms of Colours. [ Optiks Book One, Part II]

Richard said...

Newton used seven colors because he was involved in mysticism (Actually he was not a christian) and the number seven has strong mystical significance.

Richard said...

For the record re: Newton's religion (from Wikipedia):

According to most scholars, Newton was Arian, not holding to Trinitarianism.[7][19] 'In Newton's eyes, worshipping Christ as God was idolatry, to him the fundamental sin'.[22] As well as being antitrinitarian, Newton also rejected the orthodox doctrines of the immortal soul, a personal devil and literal demons.[7] Although he was not a Socinian he shared many similar beliefs with them.[7] A manuscript he sent to John Locke in which he disputed the existence of the Trinity was never published.

Anonymous said...

You ain't been blue; no, no, no.
You ain't been blue,
Till you've had that mood indigo.

David Still said...

Colour is such a complex subject. I recently thought I had it figured out: There's three dimensions, hue, value, chroma, and that's that. And I thought that a colour on the wheel that is more towards the blue than another colour is always cooler, and a colour that is more towards the red-orange than another colour on the wheel is always more warm. But I suspect it's not that simple. I'm looking forward to these posts!

r8r said...

I'm hoping to hear some argumentation about color temperature. Clearly, a blue, usually considered a cool color, can vary between cool to warm, depending on what surrounds it.

Roca said...

Recently I read a book on film-making (The Visual Story by Bruce Block) that contends that we've all learned the primary colors wrong: That the true subtractive primaries are cyan, magenta, and yellow. Wonder what you think of this assertion? Should we stop saying blue, red, and yellow? Or is it a mere technicality of language?

Don Cox said...

"Is it scientifically legitimate to merge the colors at either end, forming a circle, as Newton did?"

Yes, because we are talking about color as perceived, not about the wavelengths of light. The magentas and purples require a mixture of two dominant wavelengths, whereas red, blue, yellow and green can be shown with one wavelength each.

But the magentas and purples are still colors.

Don Cox said...

"Should we stop saying blue, red, and yellow?"

Yes, certainly. You should have stopped at least 50 years ago.

Yellow, magenta and cyan are the three used for printing, and for analog photographs. (Films and prints).

Red, green and blue are used for light sources such as TVs, monitors, or stage lighting. It is all a matter of the most efficient technology.

Some new inkjet printers use more than three primaries.

Note that anything one says about color should be followed by "but it's really more complicated than that."

Don Cox said...

"I'm hoping to hear some argumentation about color temperature."

Warm colors are the colors of everyday hot things on Earth, such as red hot coals. Blues are associated with everyday cold things like snow and ice.

Stars are much much hotter than coals, and the hottest are blue. But these are too remote from ordinary life to matter for painting.

James Gurney said...

Meredith and Don, you're right on, and I'll attempt to cover those points about red-yellow-blue and CMY as the week goes along.

Richard, thanks for the clarifications on Newton.

Everett, excellent question, and I think Don answered it well. Some of those red-violet linking colors don't seem to be optically apparent in the original spectrum, but since they have a perceptual reality, there's no reason not to bring them in.

And as Richard points out, Newton and many others have recognized that color really isn't resident in objects. Color really always turns out to be more complicate than it first appears, as you say, Don.

I'm not going to get much into warm and cool colors in this series. I've covered it on the blog in the past, and I'll come back to it later, I'm sure.

अर्जुन said...

Shocking blue, Newton knew, strange but true, 7 Is A Number In Magic!

Joseph said...

My college physics teacher of ten years ago claimed that 1 in 6 of the population can't tell the difference between indigo and violet, he claimed it was the way the brain was wired and was considered unimportant in this day and age as painting was dying out

Unknown said...


I must say I really enjoy this kind of article that helps understand how "things" work n the whys of us perceiving them as we do. It's just so helpfull to have this kind of base when you're trying to create, even if it's to go in the opposite direction; at least u know where the opposite is :)

Something u'd might be interested in making a post about (if u aren´t already), as it shows a different perspective on how light works in nature, is the "Rayleigh scattering", and/or Lord Rayleigh, the english physicist the phenomenon was named after. Besides Wikipedia, u can also find a nice article here:


Laura G. Young said...

Thanks for the insight!

For years I'd wondered at the Russian language's insistence on having two blues: light blue (голубой/goluboy) and dark blue (синий/siniy). They don't describe these as shades, but as distinctly unique, individual colors. Now I understand why.

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Unknown said...

Thank you for this series on the colour wheel James,I read your pages on it in Colour and Light, and am painting my own YRMBY wheel. I've had the pleasure of learning colour from David Briggs at Julian Ashton Art School in Sydney. His knowledge regarding optics is huge. Interestingly he taught a process of mixing the hue you want (using Munsel colour schematics) and then mixing that with a series of greys to produce colour string, and correcting for hue shifts with the root hues used to mix the desired original hue. It makes sense in a way, but an odd result is that paintings end up with a strong grey cast. It is visible when in Ashton's for classes, many of the paintings on the walls have a definite grey haze. I brought this up as a questions and was not really answered. So I have great respect for David's site in terms of the science of optics, but in terms of mixing it is a very particular method. Unusual point is that David himself paints vivid and strongly coloured work. There is much that is personal in the perception of colour, and or the preference for depiction and use of colour is my conclusion.

Btw in response to Richard, one commenter. Wikipedia is not a rigorous source of information. Newton was very much a Christian, Arianism is an old and unusual school of thought which simply is not holding the "trinitarian" view of God, they see Jesus as fully human with God's guiding or touch rather than fully god/human. It's all very complicated theology. Newton wrote over 2.2 million words on theology and church history. Including many commentary type journals on various books of the bible. Just letting you know. Not that it matters much.