Understanding and Using COLOR

A Modeler’s Perspective

By Bob Hyman

INTRODUCTION

Hobbyists who are capable of creating super-detailed models that replicate every physical aspect of a prototype object are sometimes baffled when it comes to duplicating its colors. Because of this, otherwise excellent models often appear dull, lifeless and uninteresting.  Color can become one of a modeler’s greatest assets, if properly utilized.  But to utilize color properly, one must first understand exactly what it is.

TRADITIONAL COLOR THEORY  

Our understanding of the nature of light and color came into being as modern physical science developed around the seventeenth century.  Early scientists observed a beam of sunlight is split by a glass prism into the colors of the rainbow.  They concluded that light is the source of color and identified seven basic colors in the light spectrum: red, orange, yellow, green, cyan, indigo, and purple.  Further experiments showed that just three colors could be recombined to produce white light: red, green, and blue.  Since then these three colors – red, green, and blue – have been considered as primary colors in what is called the additive spectrum.

This spectrum is called additive because when added to each other, the three primaries of this spectrum give us transparent light (what we call white light).  Moreover, when any two of the primaries are added to each other, they produce one of light’s secondary colors.  For example the addition of green light to blue produces cyan; the addition of red light to blue produces magenta; and the addition of green light to red produces yellow.  Thus the secondary colors of light are cyan (a greenish blue), magenta (a red-violet), and yellow.

The additive spectrum is sometimes referred to as the RGB (red-green-blue) system.  It is used within a color television tube to create color images.  It is also the system used by scanners, computers, and digital cameras to process and display color images.  High-resolution color (also called 24-bit color) uses eight binary bits for each of the three primary colors. The eight bits give a total of 256 (0 through 255) possible values for each primary color.  Each dot of color information can therefore be any one of over 16 million different colors.

The additive concept of traditional color theory has to give way to another concept when we deal not with light but with pigments.  Cyan, magenta, and yellow – the three secondary colors of the additive spectrum – become the primary colors of the subtractive spectrum.  According to this theory, when light illuminates an object, colors are subtracted from the light rays because the object absorbs them.  The colors that reach the eyes are those that are reflected, not absorbed by the object.  When the primaries of the subtractive spectrum – cyan, magenta, and yellow – are blended, we get black.  When we blend two of these primaries together we get red, green, or blue.

COLOR QUALITIES

There are other dimensions of color besides their relationships to each other within the spectrum.  Every color has three different qualities: hue, value, and intensity.

Hue is the quality that designates a color.  Hue tells us that turquoise is the color it is – it is not yellow-green, or something else, and so on. Technically, there are millions of hues.  Typically, hues are represented by a sampling of individual colors.  This sampling may be any number from the basic three primaries to pallets composed of 256 (or even more) colors.

Value is the lightness or darkness of a color.  The true color of an object, without reference to conditions that lighten or darken it, is called its local color.  For instance, a freight car may be painted red, and on a sunny day it looks red.  But on a rainy day, the same car is a darker, muted color – not the same red.  What is the local color of the car?  The answer is the color that you see when white light (like sunshine on a cloudless day at noon) illuminates the car with no refracting of the rays.  In other words, the local color is red, without reference to conditions that can lighten or darken it.

The darkening of a color produces a shade.  Prussian blue, for instance, is a shade of blue; it is low in value.  If you were modeling the car as it appeared on a rainy day, you would avoid it’s local color and use a shade of red.  The lightening of a color produces a tint.  Peach, for instance, is a tint of orange; it is high in value.  If you were modeling a sunny highlight on the car’s door, you would use a red tint.

Modelers often try to put two different colors of the same value next to each other.  They do not realize the importance of varying the values of the two colors.  The human eye does not distinguish unvaried values easily.  If a model of a red box car is the same value as the green of the trees and the blue of the backdrop, the viewer will subconsciously reject the modeled scene as unrealistic.

Value is relative, but it is the most important dimension in color for modelers.  Mistakes in choice of hue are far less serious than those concerning value.  Many modelers use color well, only to have their models fail because of an unsuccessful handling of a range of lights and darks.  Once you have mastered the ability to see value differences, you can become creative by adjusting the value of an area to make your model more dynamic.  Try to keep the range of values wide.  A good range is: black, dark, medium, light, and white.  Remember in building a model that light values draw the eye more than dark values do.

Darks and lights are powerful elements in a model’s composition because they help us to define shapes more readily.  Skillful use of shades and tints allows us to faithfully imitate the effects of highlights and shadows on an object without regard to the source or position of the actual illumination.

Intensity refers to the brightness, or saturation, of a color.  A brilliant yellow, a very vibrant red, and a strong, rich blue – these are said to be intense, or saturated.  Duller versions of these hues are, of course, lacking in intensity.  A color that is at 100 percent saturation is one that is as bright as possible.

 Note that brightness does not refer to value.  Colors can be bright yet quite different in value.  An intense yellow is light and therefore high in value, but an intense purple is dark and therefore low in value.  Moreover, colors can be different in intensity yet the same in value.

 For variety, it is usually best to surround an intense color with shaded or tinted colors.   Just as with values, the model’s intensities of color must be varied.  Some must be dulled by being used as shades or tints, others can be employed as pleasing spots of brilliance amid more muted colors.  Bright spots will draw the eye, just as light valued areas do.  A bright and light valued area is the most powerful attention-getting tool you have at your disposal as a modeler, but only if it is a part of a varied scheme.

WHITE AND BLACK

White light can be anywhere from very bright to very dim.  To understand this, let’s assign 300 units of energy to white light at full maximum brightness (100 units each of red, green, and blue light) and 0 units to the absence of all light.  Let’s assume that at 300 units, the white light would blind you; it’s at a level we cannot tolerate.  Around 240 units (80 red + 80 green + 80 blue) is what we should consider the ideal light that gives us the true color of an object.  As we drop lower, the whiteness begins to dim to a neutral value, or a gray.  Finally, as we approach 0 units, we arrive at a pure black.

THEORY vs. REALITY

Concepts are great for a basic understanding of the principles of light and color, but one must consider the practical applications.  First and foremost, models are seldom constructed and viewed under perfect (transparent white light) illumination.  The light source will always impart a characteristic change to the perceived color of a model.  Incandescent lights tend to have higher red content, while fluorescent lights have a higher blue content.  Even light sources that are advertised as “daylight” do not contain all of the wavelengths that are present in true sunlight.

Secondly, models are viewed differently than real-world objects.  Although the models are much smaller, they are actually viewed from a proportionally further viewpoint.  For example, an S scale model viewed from an actual distance of twenty-four inches  represents a real-world object viewed from 128 feet.  To be realistic, the modeler must add the missing 126 feet of atmospheric perspective into the modeled object in order to make it appear 128 feet away.

 Finally, the color of any object (real or modeled) is affected by the color of objects around it.  This is caused by a simple optical illusion that happens within the human visual perception process.  Simply stated, a body of color will throw its opposite value and its complementary hue onto the body of color next to it.

PIGMENT COLORS

A color theory based on the primaries of cyan, magenta, and yellow is nothing new.  In fact, since modern day color printing was developed, printers have used inks of cyan, magenta, and yellow, plus black, as their standards for printing all the other colors.  In color printing, these four primary colors are printed as minuscule dots clustered next to and on top of each other, and the effect to the naked eye is of thoroughly blended colors.

But though the printing ink primaries are cyan, magenta, and yellow, the inks themselves are not perfectly true to nature.  First of all, creating pigments that absolutely match our theory’s true primaries is almost impossible.  Yet pigments exist that come so close that a search for perfection would be pointless.

Secondly, the inks are slightly adjusted and are thus impure.  There are several reasons for the adjustment, which have to do with the consistency, lightfast quality, flow, and other ink technology issues.  However, another reason is that printed pictures are supposed to mimic what we normally see, and they would have more of a fluorescent glow or neon effect if done with true cyan, magenta, and yellow inks.  The world we see and model is, after all, mainly of colors that are a mix.

THE COLOR WHEEL

The color wheel is a device that bridges theory and practice.  All color wheels start with the primary colors cyan, magenta, and yellow.  To create the other colors on the basis of these three you derive three more, then six more, and so on, up to twenty-four.  (After twenty-four one is simply splitting hairs trying to define new colors.)

The following color wheel shows twenty-four hues.  I have shown the relative red, green, and blue (RGB) content of each hue for those of you who work color magic with computers.

Primary colors are so called because they cannot be made from any other color.  These are cyan, yellow and magenta.

Secondary colors are those formed by mixing equal parts of any two primaries, both at 100 percent saturation.  There are three secondary colors: warm red, green, and purple.

Tertiary colors are those formed by mixing one primary that is at 100 percent saturation and any other primary that is at 50 percent saturation.  There are six tertiary colors: cool red, orange, lime green, turquoise, purple-blue, and mauve-violet.

Quaternary colors are formed by mixing one primary that is at 100 percent saturation with any other primary that is at either 25 percent or 75 percent saturation.  There are twelve quaternary colors: cherry red, red, red-orange, orange-yellow, yellow-green, warm green, cool green, blue-green, blue, ultramarine blue, purple-mauve, and red-violet.

The closer together colors are in their location on the color wheel, the more related and harmonious they are.  Colors that are adjacent to each other are called contiguous colors.  Colors that are directly opposite each other are known as complements.  Complements produce interesting grays when mixed together.

The twenty-four hues shown on this color wheel are pure hues.  The pure hues are the three primaries cyan, magenta, and yellow and the colors that are created from any two of the primaries.  A pure hue does not have the third primary in its mixture.  The pure hues are bright and said to be “clean-looking” colors.

A pure hue will always consist of at least one primary at 100 percent saturation.  It can have a second primary in its mixture with a saturation from 0 to 100 percent.  For example, orange is approximately 50 percent magenta + 100 percent yellow.  Warm red is 100 percent yellow + 100 percent magenta.

SHADES

Shades are achieved by mixing the three primaries together.  A shade is a pure hue darkened by adding the primary or primaries that it does not already contain.  At least one primary must be at 100 percent saturation, while the other two can vary in their degree of saturation.  For instance, the secondary color red is composed of 100 percent magenta plus 100 percent yellow.  Add any percentage of the missing primary cyan and you get a shade of the color red.

Shades include, typically, all the browns, such as burnt sienna; olive green; and dark blues, such as Prussian blue.  Black should be ranked as a shade, because it consists of all three primaries at 100 percent saturation.

To mix a shade you can simply add the missing primary, as suggested above.  Otherwise, another good formula for mixing a shade is as follows:  Add a primary color that is not a component of the pure hue to that pure hue’s cooler contiguous color.

TINTS

Tints are achieved by lightening a color.  A tint is therefore simply any pure hue, shaded hue, or black that has been lightened by adding white.  Tints of the pure hues are considered pastel colors: pink, pale yellow, peach, light blue, aqua, lilac, and many more clean-looking light colors.  Tints of black are called grays.

ATMOSPHERIC PERSPECTIVE

Temperature is a color trait that gives us advancing and receding color.  Warm brilliant reds, oranges, and yellows appear nearer to us than cool blues, greens, and violets seen from the same distance.  Warm temperature hues are located in the top one-third of the color wheel, where every hue contains a 100 percent saturation of yellow.  The bottom two-thirds of the color wheel contains the cool hues; these have a 100 percent saturation of either magenta or cyan.  The hues in the bottom two-thirds have either no yellow or a yellow saturation below 100 percent.  Warm hues are therefore the hues from warm red clockwise on the color wheel through green.  The cool hues are from cool green clockwise through red.

Similarly, a pure hue will advance, whereas a muted, or grayed-down, color will recede.  You can give your models depth by exploiting this aspect of color.  The principle is simple: Take the intensity out of any pure hue in those areas you want an illusion of depth or distance.  Shades and tints give the impression of distance because the atmosphere has a normally muting effect upon color, as do conditions such as haze, smog, and fog.

MIXING SHADES FOR SHADOWS

The shadow on an object, which is called a form shadow, and the shadow the object causes to fall on another surface, called a cast shadow, are usually modeled differently.  Shadows follow a rule called “opposite to opposite”.  When light illuminates an object, the color temperature of the shadows will be opposite to the color temperature of the light.  For instance, if the light is warm, the shadows will be cool.  The shadow’s color will also be the complement of the light’s color.  The early morning sun is orange-yellow.  This is why in the early morning an illuminated fence post has a purplish-blue form shadow and casts a purplish-blue shadow on the snow.

But keep another “opposite” in mind:  If there is light reflected into a cool form shadow, then it will add to it some color that is opposite in temperature – a warm color.  A reflected light, besides being either warm or cool, will be affected by the color of the reflecting surface.  This is often called color bounce.  Even if the light is neutral, you should always color the form shadow with some color bounce, just for a more pleasing effect.  Think of it as simply modeler’s artistic license.

FORMULAS FOR TINTS AND SHADES

Form is modeled by the effective use of color and value.  This means defining a modeled object by the colors that indicate its illuminated and shaded surfaces. 

 To model an object that is illuminated by neutral light:

To model an object that is illuminated by warm light such as sunlight:

ADJUSTING FOR LIGHT SOURCES

Experiment with slight color variations to compensate for light sources that are not pure transparent white light.  If the model will be displayed primarily under incandescent lights, use slightly less of any warm hue (particularly reds and oranges) as you blend your local colors, tints and shades.  Also add a little extra warmth to your form shadows and cast shadows.  Conversely, if your model will be primarily illuminated with fluorescent lights, use slightly less of any cool hues (particularly blues and greens) for local colors, tints and shades, and add extra coolness to the shadows.

SUMMARY

The understanding of traditional color theory can be confusing to modelers, especially when they try to use traditional color wheels or paint manufacturers’ color chips to duplicate prototype object colors.  Even though the colors chosen may be exact duplicates, they usually fail to replicate the visual impact of the prototype.  This is because the colors on the model lack the subtle graduations in hue, value and intensity that are seen in the prototype object.  A basic understanding of color theory – as well as the proper utilization of varied hues, values and intensities – will help modelers to create models that are both prototypically correct and visually exciting.