Computers have put a vast and powerfulpalette of colors into the hands of millions of people. Theresults have not been gratifying. It often seems that noviceusers want to use all the 16 million colors in a singlegraphic.
This research seeks to understand thedifferences between artist's color and computer color inorder to suggest ways that computer art can incorporate theharmonies and subtleties found in traditional art.
Thetraditional artist's color wheel defines the primary colorsas red yellow and blue. We will call this system RYB.
Photography defines the primary colors as cyan, magenta andyellow. Computers and video use the primary colors of light,which are red, green and blue. The RGB of video can createCYM by addition and the CYM of film can create RGB bysubtraction. The RGB and CYM hues are in theory complimentary andreciprocal. In practice, film, video, computer screens and printing all have different 'gamuts' or ranges of color that can be created. For that reason, the colors you see on the screen do not match what comes out of a color printer.
Cyan, magentaand yellow used by printers have a much smaller range ofhues and values as dyes used in photography, so printers add black toincrease the value range of their colors. The primarieshowever are the same hues, so we will define the system thatincludes computers, video, printing and film as CYM/RGB
The difference between the computer palette and the colorsused by artists is one of the unexplained questions of colortheory. Usually artists will answer that these are"different systems," but that does not explain how either ofthem operates.
Diagram 1 showsboth systems divided into 12 step circles. This is way theartists lay out colors in a color wheel. The hues arefurther grouped into primary, secondary and tertiary colors.
Seeing the two systems side by side can help explaintheir differences. In RYB, red is in the 4 o'clock positionand blue is in the 8 o'clock position. This forms a triangleof the red, yellow and blue primary colors. In the CYM/RGBsystem, the primary colors of cyan, magenta and yellowoccupy the same positions as red, yellow and blue in theRYB.
In CYM/RGB, magenta is in the 4 o' clock positionin place of red. Red is at 2 o'clock, only two steps fromyellow instead of four. In CYM/RGB, red is created by mixing(subtracting) yellow and magenta. In photography andprinting, red is a secondary color, made from magenta andyellow. Until recently, only film and printing inks couldmake a pure red by subtraction, but now cyan, magenta andyellow are available as inks and gauche that can be used tomix red, blue, and all the other colors that color printingand photography can create.
Green, yellow green, andyellow are in the same position in both systems, so thatmeans that there are fewer steps between blue and green inthe RYB system.
To summarize the firstdifference between systems: RYB = more stepsbetween red and yellow, fewer steps between blue andgreen.In the RYB system, red and blue are mixed(subtracted) to make purple. There is very little overlap inthe spectral energy distribution of red and blue, so thesubtraction of the two hues yields a very dark purple.Magenta is the same hue, but is a much higher value. Magentacontains red and blue light at full strength, so both redand blue can be subtracted from magenta. The colors oneither side of magenta also have a much higher value inCYM/RGB, making it possible to mix many violets andred/violets not possible in RYB. Compare magenta at 4o'clock in the CYM/RGB system with purple at 6 o'clock inthe RYB system. It is hard to believe, but these are samehues but at different values.
Seconddifference: The RYB subtracts red and blue to makepurple. CYM/RGB subtracts from magenta to make both red andblue.
Ostwald, who defined color on a scientificbasis, defined opposite colors on the colorwheel as theafterimage of the color. By this definition, blue is theopposite of yellow. Itten wrote the most popular book onartist's color. He said that Ostwald's definition was notuseful for artists. Itten insisted that blue was the colorthat mixed with yellow to make green. In the CYM/RGB system,when yellow and blue are mixed (subtracted) the result isblack.
Diagram 2 shows the blues of the CYM/RGB mixed with yellow.Blue at 6 o'clock in this system mixed with yellow yieldsblack. Cyan at 8 o'clock and yellow yields a bright green.At 7 o'clock is an in-between cyan/blue that yields a darkergreen. Both greens are the same hue, but the mix at 7o'clock is a much lower value. This point is very important.This darker green looks more like the green in artist'spaint sets. In the artist's RYB system, blue is usuallydefined as a hue opposite orange rather than the opposite ofyellow. This blue yields a dark green or even a gray-greenin some pigments when mixed with yellow.
Third difference: Blue is defined as adifferent hue in RYB, one closer to green and oppositeorange.In the RYB system there is one step betweenblue and green, and Itten calls this hue turquoise in hisdescription of artist's color. Because it is created by thesubtraction of yellow and blue, this turquoise is a muchlower value than cyan. Cyan used in film and ink containsthe entire spectrum of green and blue. It can be used to mix(subtract) a very bright green and bright blue, whichturquoise cannot. The difference is so dramatic that mostobservers would say the two (cyan and turquoise) aredifferent hues.
Fourth difference:In RYB cyan is a much lower value and is calledturquoise. Green in RYB is also a much lower value.Understanding the relation of color to value is the key tounderstanding the difference between computer color andartist's color. The difference in value between cyan (85%)and turquoise (47%) is 38%. The difference between magenta(54%) and purple(14%) is a whopping 40%. These are the samehues, but different values in the two systems
CYM/RGB isa system that can create a great range of hues and values.There are several reasons to consider it the "correct"system, and the RYB system incorrect.
CYM/RGB can beused to create all the hues and values of RYB, but notvice-versa. RYB misses vast ranges of hues and values;especially violets, bright greens, and blue-greens.
Opposite colors in CYM cancel each other out to createblack, and in RGB, the primaries combine to create a purewhite. Equal amounts of three CYM/RGB colors create verypure grays, almost impossible to create in RYB. In RYB allthree colors together create brown.
After all this issaid, the fact still remains that when the power of computercolors gets into the hands of students and computer artists,the colors they choose are usually godawful. RYB colors canalso be misused, but artists who use the RYB color wheel inthe traditional way to pick complimentary pairs and triadswill have much more pleasing results. The goal of thisinvestigation is to understand what is "right" about the RYBsystem.
Diagram 3 shows the RYB and RGB/CYM color wheels convertedto grayscale. The RGB/CYM color wheel contains all purecolors that are defined as 100% brightness in the colorpicker. As you can see, the primary colors of light (colorphosphors) built into the picture tube of computer monitorsand television sets actually have a light value of red(46%), green (80%) and blue (25%). If you look at the purehues in the color picker, they will all be listed at 100%brightness, and will all have their intensity set to themaximum at 255. Notice how green appears very bright on thecomputer, much brighter than red. In artist's colors, red isusually the same value as green or slightly brighter.
The subtractive primaries of cyan (85%), magenta (54%), andyellow (95%) have more brightness than RGB because they areeach composed of two of the RGB primaries of lightilluminated at full strength.
The RYB wheel shows grayvalues that are much closer together. Opposite colors andadjacent colors are very close in value. The blue and greencolors are darker, as we discussed above. There is an almostuniform light-to-dark contrast from yellow at the top of thewheel to dark purple at the bottom. This reduces the valuecontrast between opposite and triadic compliments, creatingpleasant harmonies.
These two gray wheels allow one tovisualize the differences between the two systems verygraphically. By understanding the relationship of color andvalue it will be possible for artists to control theextremes of value differences in computer color and approachthe close harmonies of traditional paint.
Please visit my Microcomputer Art classat
CaliforniaState University Long Beach
Please visit PerceptGallery
Percept is an alternative exhibition space
that opened in 1981 in Downtown Los Angeles
to showCalifornia Light and Space Art,
and is now reopened incyberspace.
Percept is an alternative exhibition space
that opened in 1981 in Downtown Los Angeles
to showCalifornia Light and Space Art,
and is now reopened incyberspace.
