Understanding Color:

An Introduction for Designers

Chapter 2: A Little Light on the Subject

Part 1

Light

Only light generates color.

Light is visible energy that is emitted by alight source.

A light source can be:

the sun...

a luminous panel...

a neon sign...

a light bulb...

or a monitor screen.

The eye is uniquely adapted to receive

light.

The retina of the eye receives a stimulus - the energy signal - and

transmits it to the brain, where it is identified as color.

Light sources emit this visible energy in pulses, or waves.

All light travels at the same speed, but waves of light energy are emitted at

different distances apart or frequencies.

The distance between the peaks of these energy emissions is called

wavelength. Wavelengths of light are measured in nanometers (nm).

The human eye is able to sense wavelengths of light ranging from about 380

nm to about 720 nm.

Individual wavelengths are sensed as discrete colors, or hues.

Red is the longest visible wavelength at 720 nm.

Violet is the shortest visible wavelength at 380 nm.

The wavelength of visible light goes in order from longest to shortest:

REDORANGEYELLOWGREENBLUEINDIGOVIOLET

“ROYGBIV” is an acronym for these wavelengths, which are the colors of the visible spectrum.

“ROYGBIV” is an acronym for these wavelengths, which are the colors of the visible spectrum.

Here is an easy way to remember the order:

Different types of light sources emit the various wavelengths (colors) at different levels of energy. One light may give off a particular wavelength at

such a low level of energy that it is barely visible...

...while another emits it so strongly that it is seen as a brilliant color.

Although the color is the same, the intensity of the color experience is very

different.

The human eye is most sensitive to light in the middle range of the visible spectrum and sees

these colors, the yellow-green range, most easily.

Yellow-green light can be sensed at a

lower level of energy than other colors.

There is visible light and color beyond the range of human vision.

Some animals and insects can sense colors that are

beyond the range of human vision.

For instance, jumping spiders and bees can sense ultraviolet light.

Colors on the edges of human vision can also be sensed with special optical equipment.

For instance, there are special filters and lenses that you can attach to a camera to take photos using only infrared light.

Additive Color:Mixing Light

Sunlight is sensed as white, or colorless, but it is actually made up of a mixture of colors (wavelengths) that are emitted in a continuous band. Individual colors can be seen when sunlight is passed through a prism.

The glass of the prism bends, or refracts, each wavelength at a slightly different angle so that each color emerges as a separate beam.

Under the right atmospheric conditions water droplets will form natural prisms, and the

compoenent colors of sunlight can be seen as a rainbow.

Other light

sources, like light

bulbs, emit light

perceived as

white.

But light sources do not have to emit all of the visible wavelengths for white light to

result.

White light is produced as long as a source emits the red, green, and

blue wavelengths in roughly equal proportions.

Red, green, and blueare the primary colors of light.

Mixing two of the primary colors of light produces a new color.

Cyan, magenta, and yellow are the secondary colors of light.

Wavelengths can be combined in

unequal proportions to create additional

colors.

Two parts green light and one part red at equal levels of

energy provide yellow-green.

Two parts red light and one part green at equal levels of energy

provide orange.

All hues, including violets and browns that are not found as wavelengths in the visible

spectrum, can be produced in light by mixing the light primaries in different

proportions.

White or colored light seen as a result of a combination of wavelengths is called anadditive mixture or additive color.

Lamps

Lamps are the principle man-made light sources.

“Lamp” is the correct term for a light bulb.

The fixture that holds the lamp is a luminaire.

A general light source is a lamp that produces light that is white.

General light sources provide ambient light, which is general area

lighting.

A lamp that is missing one or more of the primary colors gives off colored

light.

It is NOT a general light source.

The lamps in neon signs are one example of a light source emitting a narrow range

of wavelengths

General light sources each produce wavelengths in a characteristic pattern

called a spectral distribution curve or spectral reflectance curve.

The spectral distribution curve shows which wavelengths are actually present and the strength of each wavelength relative to the others for that

particular type of lamp.

Spectral distribution determines (and describes) the color quality of a light source.

NeutralWarm Cool

We think of natural and artificial light as two different entities, but ALL light is visible

energy.

Light sources can

be differentiated from other

each other in two ways:

•spectral distribution

•apparent whiteness

Daylight is the standard of whiteness for man-made light sources, and because response to sunlight is part of our genetic makeup, it also helps to determine whether light from a given source will be sensed as more or less natural.

About 40% of man-made interior lighting is used for domestic purposes.

The balance is used to illuminate public and commercial spaces.

Incandescent lamps, like the sun, produce light by burning.

The light they emit is a small byproduct of heat - only about 5% of the energy used by an

incandescent lamp results in light.

Candlelight, firelight, and incandescent lamplight are sensed as comforting

because they emit light in the same way the sun does.

The apparent whiteness of an incandescent lamp depends on the

temperature at which it burns, called its color temperature.

Color temperature in

lamps is measured in

degrees Kelvin (K).

A typical incandescent lamp burns at a relatively low temperature, around

2600 - 3000 K.

Lamps that burn hotter emit bluer light; very white light is hottest of all.

A halogen lamp is a type of incandescent lamp with a gas inside the glass envelope that causes it to

burn at a high temperature resulting in a bluer white.

The color temperature of a lamp is used as a measure of whiteness for the color of light

produced by the lamp.It does not help to predict how a light source will

render the colors of objects.

As a designer, you will need to use mockups in field conditions to make sure that the lamps you use deliver the right quantity and quality of light

for each situation.

Fluorescent lamps

produce light in a

completely different way.

The interior of the glass bulb is coated with phosphors, substances that emit light when they are bombarded with electrical energy.

The color of a fluorescent lamp depends on the particular makeup of

its phosphor coating.

What is “phosphor?”

Fluorescent lamps do not burn, so they do not have an actual color

temperature, but they are assigned an “apparent color temperature” to indicate their degree of whiteness.

Fluorescent lights produce separate bands of energy instead of a continuous spectrum, but will still emit all wavelengths at similar levels of energy. Because of our eye’s sensitivity to yellow-green,

ordinary fluorescent lamps appear yellow-greenish.

Light that imitates sunlight - continuous spectrum - is sensed as the most comfortable, welcoming

and natural.

Some lamps are marketed as “full spectrum,” but that doesn’t really tell you anything about the

temperature of the light since it could have various strengths of wavelengths.

Current emphasis on the environment has led to new sources of light like the LED lamp.

LED lamps produce light at low operating cost by combining the output of red, green light-

emitting diodes.

LED lamps produce a white, strong light that is excellent for limited uses like car headlamps, but is

problematic in interior environments because it contains only the three primary colors and does not

have a continuous spectrum.

Lighting level refers to the quantity of available

light, regardless of its color makeup.

Lighting level describes the total amount of light coming from the source and is unrelated to its spectral distribution.

A lamp may give off more or less light, but its spectral distribution - the pattern of energy emitted at the different

wavelengths - is identical for that lamp no matter what quantity of light it gives off.

Too little available light makes it hard to see colors.

Excessive and uncontrolled light falling on a surface can also impair color perception.

Glare is an extreme, physically fatiguing level of general light. Glare obliterates

color perception and can be temporarily blinding.

Reflectance or luminance is a measure of the amount of light falling on a surface that is reflected

back.

It is a measure of the total amount of light reflected, not the individual

wavelengths, or colors.

Reflectance is so important to some

products, like interior and

exterior paints, that the

percentage of light reflected back from

each color, called its LRV (light-

reflecting value), is part of the basic information the

manufacturer provides.

Lighting level affects our ability to see value, and to make sense of what we see,

but the color of the light does not.

Vision is the sense that detects the environment and objects in it through the eyes, and is the only way in which color is

perceived.

Color vision is experienced in two different ways: either as

light directly from a light source, or as light reflected from an

object.

In the illuminant mode of vision, colors are experienced as direct light reaching

the eye, like the colors of a monitor screen or a neon sign.

In the object mode of vision, colors are seen indirectly as reflected light.

The tangible things of the real world - objects and the environment - are seen in the object mode of

vision.

The illuminant mode of vision has two variables:

•the characteristics of the light source

•and the characteristics of the viewer.

In the illuminant mode of vision, colors are relatively stable.

But every viewer brings their own personal sense

and interpretation to the perception

of color.

Part 2

In the object mode of vision, color is seen as light

reflected from a surface.

Color perception in the object mode of vision has three

variables:•the characteristics of the light

source,

•the individual viewer’s visual acuity for color and interpretation of it, and

•the light-modifying characteristics of the object.

Light leaving a light source is the incident beam.

The reflected beam is light that leaves a surface and

reaches the eye.

The material an object is made of modifies light in one of three

ways:

•Transmission

•Absorption

•Reflection or scattering

Transmission: the material allows light to pass through, as through

glass.

Absorption: the material soaks up light reaching it like a

sponge, and the light is lost as visible. It can no longer be seen.

Reflection or scattering: Light reaching the material bounces off it,

changing direction

Colorants are special materials that modify light by absorbing some

wavelengths and reflecting others.

A colorant can be integrated into the substance of a material, like a color-

through plastic...

...or applied to a surface as a coating.

Colorants are also called color agents, dyes, pigments, and dyestuffs,

depending on their makeup or end use.

A white colorant reflects, or scatters, all wavelengths of light, and a black

colorant absorbs all of the wavelengths of light.

Other colorants modify light selectively.

Here the colorant in bananas absorbs all colors except yellow which is reflected.

In order for an object to be seen as a color, the wavelengths that its colorant

reflects must be present in the light surface.

A red dress seen under green light is a black dress. In a parking lot illuminated by the light of yellow

sodium lamps, red, green and blue cars are indistinguishable from each other. Only yellow cars

can be located by their color.

Colorants don’t absorb and reflect individual wavelengths perfectly. They may absorb part of a wavelength and reflect part of it, or reflect more than one wavelength. So many possibilities exist that the range of visible colors is nearly infinite.

Colors seen as the result of the absorption of light are subtractive mixtures.

A Macbeth lamp has a spectral distribution similar to sunlight and is

often used under laboratory conditions to measure color.

However, such a lamp has little use for artists since their products are

seen under all types of light, and by all types of people.

Two objects that appear to match

under one light source but not under another

exhibit metamerism. The objects are

called a metameric

pair.

Because materials differ in their ability to absorb colorants or accept them as coatings, it is

virtually impossible to color match two very different materials.

It is really only possible to reach an acceptable match, one that is

pleasing to the eye.

If your colors are an acceptable match under both fluorescent and

incandescent lights, they will probably be acceptable under

nearly all conditions.

A sample submitted for color matching is a standard.

A match that is perfect under any light conditions is possible only

when the original standard and the new product are identical in all

ways.

Surface is the outermost layer of a thing,

its “skin.”

Different surfaces - rough, smooth, or in between - have an impact on the

way that colors are perceived.

Value refers to the relative lightness or darkness of a hue.

Only the perception of value is affected by surface texture.

Surface texture has no effect on hue, but a rough surface will look darker than a smooth surface of the same

color.

The smoother the surface, the greater the amount of light that is reflected

back directly.

A specular surface is glossy, or mirror-like.

Light leaving a specular surface is reflected so immediately, and so

directionally, that most or all of it is seen as white light.

When a specular surface is viewed from an angle that is not the same as the

angle of the incident beam, some light reaching the underlying colorant can be

seen.

The color of a sequined garment is only visible when the sequins are viewed at

an angle that allows the color to be visible.

A matte surface is a smooth surface that is very slightly, even

microscopically, roughened.

Colors on a matte surface have a flatness and unifsormity under nearly

all lighting conditions.

Textured surfaces are dynamic and lively.

Incident light scatters in random directions producing a surface with

both light and dark patches.

Texture is most apparent under point light sources, like sunlight or

incandescent lamps.

Light from a point source originates from a single location, or point, and

the beams of light emitted are parallel.

Fluorescent lights are linear light sources. Linear light sources emit a broad-spread light that is essentially

non-directional

Light from a linear source does not reach the surface at an angle in the same way as a point light source.

Even heavily textured surfaces tend to appear flat and uniform under

fluorescent (or other linear) lighting.

Point Linear

LED lamps are currently offered as

both linear and point sources, but LED lamps are an

emerging technology and

their rendition of color and surface is difficult to evaluate

at this time.

The sharper the angle of incident light, the more directional

the reflected beam will be.

Raking light describes light from a source that is positioned at an acute

angle relative to a surface.

Specular surfaces appear more glossy, and textured surfaces dramatically

rougher, under raking light.

Varying the textures of a surface allows designers to create a an effect of two or more colors (or more accurately, lighter and darker

variants of a single hue) using only one material.

A piece of yarn, seen on its long side, is relatively smooth. Cut ends of the same yarn ( a pile, or nap)

reflect the identical wavelength but scatter light more widely and appear darker.

A small amount of light is lost each time that light travels from a source to a surface, and when light reaches a surface, a very small

amount reflects back immediately.

The sum of this light loss can be so slight that as a practical matter it is unimportant.

The light that remains is reflected, absorbed, transmitted, or a combination of these.

If all of the light reaching an object is either reflected or absorbed, the object is opaque.

If all (or nearly all) of the light reaching an object or material is transmitted, that object is

transparent.

When some of the light reaching an object or material is transmitted and some is reflected,

the object is translucent.

A translucent material can be white or a color, depending on its selective transmission and

reflection of various wavelengths

Translucent materials may allow a great deal of light to pass through (and be very translucent) or transmit very little light (and be barely translucent).

The terms transparent and translucent are not interchangeable. A truly transparent material is like window glass: for all practical purposes, it is

invisible.

A translucent material is detectably present, no matter how sheer it may be.

Iridescence is an attribute of surfaces on which the hue changes as the observer’s angle

of view changes.

The changes from blue to green that are seen in a butterfly’s wings as it flies...

the flashes of red, purple, and green in the black feathers of a Grackle...

or the brilliant and changing colors of soap bubbles and oil films are iridescence.

Iridescence is an optical phenomenon that occurs with reflected light.

The color is produced by the structure of a surface that amplifies some wavelengths of light and suppresses others, depending on the angle

of the light reaching it.

The amplification

of light makes iridescent

color extremely vivid – the color that

reaches the eyes may be

reflected, but in the absence of a modifying

colorant it is sensed as pure light.

Because no colorant is involved – nothing that absorbs some wavelengths of light

and reflects others – it is sometimes called structural color.

Iridescent textiles are

brilliantly shimmery,

seeming to be one color at one

angle of view and a second

color as the fabric moves.

Iridescence in textiles is

produced in a variety of ways.

There are silk yarns with a

molecular structure that

creates iridescence as

well as synthetic yarns with

similar properties.

Most iridescent textiles, however, are made using special yarns and techniques of weaving. When the

warp and weft are made from differently colored and light-reflective yarns, each color appears, vanishes, and reappears as the viewing angle

shifts.

There are paints and inks with light-reflecting properties that create convincing iridescent effects on a page. As the observer’s position changes, the

color changes.

An impression of iridescence is difficult to create on a screen, because light leaving a screen reaches

the eye directly, no matter what the viewer’s position or movements.

Luminosity is a word that appears often in color study.

Its real meaning is the attribute of emitting light without heat.

A luminous object is light-reflective, but it does not emit

heat.

The word “luminous” is used often to describe very light-reflecting colors and media with a great deal of light reflectance, like watercolor, dyes, or markers.

Indirect light occurs when light from a light source reaches a broad, light reflective plane

that re-reflects it onto a second surface or object.

In order for this to happen, the light source, the reflective surface, and the target surface or

object must be positioned at similar angles to one another.

Moonlight is a familiar form of indirect light. The moon is luminous: it reflects light but does not emit its own energy. Its surface reflects

the light of the sun to the earth.

Each time light travels, some of it is lost through scattering. Moonlight is weaker than sunlight

because much of the sun’s light has been scattered and lost, first on its way from the sun to the moon,

then again from the moon to the earth.

Indirect light works in the same way that moonlight does. Light reaching a white surface is redirected to a target area. The indirectly lit area appears darker than it would under direct light, but no change in its apparent hue takes place.

Indirect color is a form of indirect light. Indirect color occurs when general light reaches a highly reflective color on a broad plane.

Some of the general light–and a good deal of the strong color–will reflect onto any surface that is positioned to receive it.

One way to describe the phenomenon of color reflected from one surfact to

another is plane reflection.

The design applications most vulnerable to this are architecture and interior design, where planes of color on

walls, floors, and ceilings interact with directional light sources to create potential conditions of light and color

reflections.

Filters are materials that transmit (pass through) some wavelengths of light and absorb others.

A red filter placed between a light source and an object allows only the red wavelengths to pass

through. Other wavelengths are absorbed.

Filters are powerful

modifiers of light, so they must be

used with real understanding of

their effects.