Musings on Color

Disclaimer: Color science is a lot more complicated thananybody thinks it is. Although I have an interest in this stuff, I've neverdone any formal study or research on it. In other words, I have noidea what I'm talking about.

July 28, 2013: Several updates have been made: I havechanged the names of the tertiary colors to reflect what I currently call them,upgraded all the graphics to nice smooth SVGs, added another couple of colorwheels, and made edits to the text.

To the left is the HSV/HSL/HSB color wheel. The primary colors are the RGBprimaries, red, green,and blue. The secondary colors are the CMYK primaries,cyan, magenta, andyellow. The tertiary colors areorange, chartreuse,aquamarine, azure,violet, and rose.

Combining complementary colors in this system results in gray.

To the left is the color wheel taught in art classes. The primary colorsare red, yellow, andblue. The secondary colors areorange, green, andviolet. The tertiary colors arescarlet, gold,chartreuse, cyan,indigo, and magenta.

This color wheel expands the range of oranges and purples, at the expenseof greens, blues, and pinks. Because of this, combining complementary colorsin this system results in various earth tones (or in other wordsbrown).

The Lab color system defines a color by lightness along one axis (the Lin Lab) and hue along two separate a and b axes. One runs from red to green,and the other runs from yellow to blue. The idea is that no color can be redand green at the same time, or yellow and blue at the same time.

The "red," "green," "yellow," and "blue" colors used by Lab are actually notquite the same as the red, green, yellow, and blue colors used here, but if wepretended they were and treated a and b as x and y coordinates, we would get thecolor wheel pictured to the left. The primaries are red,yellow, green, andblue, and the secondaries areorange, chartreuse,cyan, and magenta.

The Apple II used some wacky properties of the NTSC color system to achieveits color graphics. It's all pretty complicated and outside the scope of whatI even care about. In high-resolution graphics mode, you could get four colors(other than black and white), which came in two groups. If the high bit of thebyte in memory was cleared, the pixels represented by that byte would appeareither green or magenta (or white, if two consecutive bits were set). If thehigh bit was set, the pixels would appear either orange or blue (or white).In the YIQ color system, the I axis runs from cyan to orange, and the Q axisruns from green to violet. Therefore, what that high bit was doing wasdetermining which axis the color went along!

The way the Apple II's video worked (what I called "Apple II VideoDisplay Theory") was the subject of a discussion on comp.sys.apple2.I created the color wheel to the left during this discussion, based on myobservations. The primaries are magenta,orange, green, andblue, and the secondaries arered, yellow,cyan, and violet.

Of course, my understanding of YIQ was lacking, and that color wheel doesnot resemble YIQ at all. YIQ actually looks a lot more like this color wheelinstead. The primaries are orange,green, cyan, andviolet. The secondaries arerose, yellow,aquamarine, and blue.The tertiaries are magenta,red, gold,chartreuse, two other greensI don't care to name,azure, and indigo.

YIQ is used with the NTSC television standard, which is probably the mostsubjective and least consistent with respect to color. This is why NTSC issaid to stand for Never Twice the Same Color.

To the left is an attempt by me to unify the HSV/HSL/HSB color wheel withthe color wheel taught in art classes. The RGB primary and secondary colorsand traditional primary and secondary colors are all represented as primaryand secondary colors in this system. The primaries are red,yellow, cyan, andviolet, and the secondaries areorange, green,blue, and magenta(making this the dual of the "Apple II Video Display Theory" color wheel).The tertiaries are scarlet, gold,chartreuse, aquamarine,azure, indigo,purple, and rose.

I call this system the Rayalaka system, as it was originally concieved aspart of a personal project called Rayalaka.It is the basis of the color presets available inRainbowDashboardand other Kreative Software products.

If we wanted to keep red, green, and blue as primaries, this could be doneby promoting aquamarine to a secondary color, resulting in this color wheel.The primaries once again become red,green, and blue, but nowthere are two sets of secondaries, one being cyan,magenta, and yellow,with the other being a close approximation of traditional secondaries,orange, aquamarine,and violet. The tertiary colors arescarlet, gold,chartreuse, the two greenswithout a name from the YIQ color wheel,azure, indigo,purple, and rose.

While this color wheel does include the sum total of all colors I've talkedabout so far, it does have some weird properties: there are two sets ofsecondaries, making the complement of any primary or secondary color end upas a tertiary color.

And Now the "Interesting" (Read "Most Quackerish") Part

The visible light part of the electromagnetic spectrum runs from about800nm to 400nm, or 400THz to 800THz (using one significant figure, of course,which ought to make this entire endeavor invalid). Notice that 800THz is twicethe frequency of 400THz. What else does that sound like? Oh yeah, octaves inmusic. Is it possible that the electromagnetic spectrum comes in octaves too,but we can only see one octave of it? If you take violet light and shift itcloser and closer to ultraviolet, it gets a little redder. If you're imaginingthings, at least.


© 2002-2006 Andrew T. Young

First of all, I'd like to see what the visible part of the electromagneticspectrum looks like, and try to locate "precisely" where pure red, green, etc.lie. Unfortunately, a computer monitor is poorly suited to display a spectrum.It would have to be as bright as the sun to even get close to adequate. It seemsthe only medium suitable to display monochromatic color is... well, monochromatic color.Accordingto Andrew T. Young, the best we can get is the two spectra to the right,the left being the brightest and the right being the best compromise betweenbrightness and accuracy.

Based off these spectra, it "appears" (to me at least) thatred is around 610nm or 490THz,orange around 590nm or 510THz,yellow around 570nm or 525THz,green around 550nm or 545THz,cyan around 490nm or 610THz, andblue around 465nm or 645THz.Of the more difficult-to-place colors, magenta(or possibly rose?) appears somewhere around630nm or 475THz, aquamarine around 520nm or 575THz,indigo around 455nm or 660THz, andviolet around 440nm or 680THz.

Color	λ	f	"Note"
magenta	630nm	475THz	A₄₄
red	610nm	490THz	A₄₄
orange	590nm	510THz	A^#₄₄
yellow	570nm	525THz	A^#₄₄
green	550nm	545THz	B₄₄
aquamarine	520nm	575THz	C₄₅
cyan	490nm	610THz	C^#₄₅
blue	465nm	645THz	D₄₅
indigo	455nm	660THz	D₄₅
violet	440nm	680THz	D^#₄₅

Given A₄ = 440Hz, and by extension middle C = C₄ = 261.626Hz,we can try to take these electromagnetic frequencies, reinterpret them as soundfrequencies (making millions of scientists cringe in the process), and convertthem to musical notes. The result is the table on the left.

From yellow to blue, we have a pretty satisfactory progression. Which isgood, because the "ribbons" of these colors on the spectrum are pretty thin.However, before and after yellow and blue, the "notes" bunch up. We can fudgeit and bring those notes up and down, because we have some leeway with those(though not nearly half as much as I'm kidding myself).

F^#	G	G^#	A	A^#	B	C	C^#	D	D^#	E	F
↓	↓	↓	↓	↓	↓	↓	↓	↓	↓	↓	↓
?	Magenta	Red	Orange	Yellow	Green	Aquamarine	Cyan	Blue	Indigo	Violet	?

What, then, are F and F^#?

Notice that red and green are three semitones apart, as are green and blue,and blue and F. Human beings have three types of cones in their retinas fordetecting color: one for red, one for green, and one for blue. Birds have afourth type of cone that detects ultraviolet light. Therefore F is ultraviolet,because reasons, and we can say F^# is infrared if we like, or evensquant or octarine.

F^#	G	G^#	A	A^#	B	C	C^#	D	D^#	E	F
↓	↓	↓	↓	↓	↓	↓	↓	↓	↓	↓	↓
Infrared	Magenta	Red	Orange	Yellow	Green	Aquamarine	Cyan	Blue	Indigo	Violet	Ultraviolet

We can take the two ends of the spectrum and tie them together,giving us the color wheel on the left. The bold lines separatethe colors we can see from those we cannot see.

There is something disconcerting about this wheel, in that the two squares(representing RGB and CMY) are not duals of each other, like RGB and CMY are.This has the consequence that complementary colors are not the same distancefrom each other: green and magenta and blue and yellow are four semitones apart,but red and cyan are five semitones apart. So, for the heck of it, we're gonnathrow in some more colors for no good reason, giving the color wheel on the right.

And now, the color scientists can stop having a heart attack,and we can get back to our regularly scheduled programming.