Re: How do atoms of an object absorb or reflect photons/light to give color?

Hello

I must admit I have troube to understand the real question. Maybe that what confused the others.Should my answer below not be satisfying it might help to rephrase your question.

Let me see if I understand what you ask:

• Do you want to know what happens to a photon when it hits a molecule?
• Or maybe how colors .Do you ask what makes a white piece of paper white?
• Or a black piece of coal black?

Color is the physical phenomenon of light or visual perception associated with the various wavelengths in the visible portion of the electromagnetic spectrum (see below what i have to say about the Spectrum). As a sensation experienced by humans and some animals, perception of color is a complex neurophysiological process. The methods used for color specification today belong to a technique known as colorimetry and consist of accurate scientific measurements based on the wavelengths of three primary colors. LIGHT Interaction with Material

When light strikes a material, it interacts with the atoms in the material, and the corresponding effects depend on the frequency of the light and the atomic structure of the material. In transparent materials, the electrons in the material oscillate, or vibrate, while the light is present. This oscillation momentarily takes energy away from the light and then puts it back again. The result is to slow down the light wave without leaving energy behind. Denser materials generally slow the light more than less dense materials, but the effect also depends on the frequency or wavelength of the light.

Materials that are not completely transparent either absorb light or reflect it. In absorbing materials, such as dark colored cloth, the energy of the oscillating electrons does not go back to the light. The energy instead goes toward increasing the motion of the atoms, which causes the material to heat up. The atoms in reflective materials, such as metals, re- radiate light that cancels out the original wave. Only the light re- radiated back out of the material is observed. All materials exhibit some degree of absorption, refraction, and reflection of light. The study of the behavior of light in materials and how to use this behavior to control light is called optics.White light is composed of electromagnetic vibrations, the wavelengths of which are evenly distributed from 35 to 75 millionths of a centimeter (about 14 to 30 millionths of an inch). If the intensity of these vibrations is strong, the light is white; if the intensity is less, the light is grey; and if the intensity is zero, the light is nonexistent or black. Light composed of vibrations of a single wavelength in the visible spectrum differs qualitatively from light of another wavelength. This qualitative difference is perceived subjectively as hue. Light with a wavelength of 0.000075 cm (0.000030 in) is perceived as red, and light of 0.000035 cm (0.000014 in) wavelength is perceived as violet. The quality of the intermediate wavelengths is perceived as blue, green, yellow, or orange, moving from the wavelength of violet to that of red.

The color of light of a single wavelength or of a small band of wavelengths is known as a pure spectral color or hue. Such pure colors are said to be fully saturated and are seldom encountered outside the laboratory. An exception is the light of the sodium-vapor lamps used on some modern highways, which is almost fully saturated spectral yellow. The wide variety of colors seen every day are colors of lower saturation, that is, mixtures of light of various wavelengths. Hue and saturation are the two qualitative differences of physical colors. The quantitative difference is brilliance, the intensity or energy of the light.

Now let's talk about Primary Colors.

The human eye does not function like a machine for spectral analysis, and the same color sensation can be produced by different physical stimuli. Thus a mixture of red and green light of the proper intensities appears exactly the same as spectral yellow, although it does not contain light of the wavelengths corresponding to yellow. Any color sensation can be duplicated by mixing varying quantities of red, blue, and green. These colors, therefore, are known as the additive primary colors. If light of these primary colors is added together in equal intensities, the sensation of white light is produced. A number of pairs of pure spectral colors called complementary colors also exist; if mixed additively, these will produce the same sensation as white light. Among these pairs are certain yellows and blues, greens and blues, reds and greens, and greens and violets.

Does this anwer your question?

Most colors seen in ordinary experience are caused by the partial absorption of white light. The pigments that give color to most objects absorb certain wavelengths of white light and reflect or transmit others, producing the color sensation of the unabsorbed light.

The colors that absorb light of the additive primary colors are called subtractive primary colors. They are red, which absorbs green; yellow, which absorbs blue; and blue, which absorbs red. Thus, if a green light is thrown on a red pigment, the eye will perceive black. These subtractive primary colors are also called the pigment primaries. They can be mixed together in varying amounts to match almost any hue. If all three are mixed in about equal amounts, they will produce black. An example of the mixing of subtractive primaries is in color photography and in the printing of colored pictures in magazines, where red, yellow, black, and blue inks are used successively to create natural color. Edwin Herbert Land, an American physicist and inventor of the Polaroid Land camera, demonstrated that color vision depends on a balance between the longer and shorter wavelengths of light. He photographed the same scene on two pieces of black-and-white film, one under red illumination, for long wavelengths, and one under green illumination, for short wavelengths. When both transparencies were projected on the same screen, with a red light in one projector and a green light in the other, a full-color reproduction appeared. The same phenomenon occurred when white light was used in one of the projectors. Reversing the colored lights in the projectors made the scene appear in complementary colors.

Then there is absorption The mechanism of the absorption of light by substances to produce color is obscure. It is apparently a function of the molecular structure of the substance. In the case of organic compounds, only unsaturated compounds show color, and their hue can be changed by altering the compounds chemically. Inorganic compounds are generally colorless in solution or liquid form, except for compounds of the so-called transition elements.

Color is also produced in other ways than by absorption. The colors of mother-of-pearl and of soap bubbles are caused by interference. Some crystals show different colors when light is passed through them at different angles, a phenomenon known as pleochroism. A number of substances show different colors by transmitted and reflected light. For example, a very thin sheet of gold appears green by transmitted light. The "fire" of certain gems, notably the diamond, is due to the dispersion of white light into its component spectral hues, as in a prism. Some substances, when illuminated by light of one hue, absorb this light and reradiate light of a different hue, always of longer wavelength. This phenomenon is called fluorescence, or, if delayed, phosphorescence (see Luminescence). The blue of the sky is caused by the scattering of the short wavelength blue components of white sunlight by tiny particles suspended in the atmosphere. A similar scattering can be observed in a darkened movie theater. Seen from the side, the light beam from the projector appears blue, because of the smoke and dust in the air; yet the light on the screen is white.

But let's read on and see if this little abstract on Radiaton might help.

Radiation, in physics, process of transmitting energy through space. Such radiation can consist of waves or particles. Waves and particles have many characteristics in common; usually, however, the radiation is predominantly in one form or the other. Mechanical radiation consists of waves, such as sound waves, that are transmitted only through matter. Electromagnetic radiation is independent of matter for its propagation; speed, amount, and direction of energy, however, are influenced by the presence of matter. This radiation occurs in a wide variety of energies, with visible light about in the middle of the range. Electromagnetic radiation carrying sufficient energy to bring about changes in atoms that it strikes is called ionizing radiation (see Radiation Effects, Biological). Particle radiation also can be ionizing if it carries enough energy. Like electromagnetic radiation, which it resembles, it does not require matter for its propagation. Examples of particle radiation are cosmic rays, alpha rays, and beta rays. Cosmic rays are streams of positively charged nuclei, mainly those of hydrogen. Cosmic rays may also contain electrons, protons, gamma rays, pions, and muons. Alpha rays are streams of positively charged helium nuclei. Beta rays are streams of electrons.

The spectrum of particle and electromagnetic radiations ranges from the extremely short wavelengths of cosmic rays and electrons to radio waves hundreds of kilometers in length .

Between these limits the spectrum includes gamma rays and hard X rays ranging in length from 0.05 to 5.0 Å. Softer X rays merge into ultraviolet light as the wavelength increases to about 500 Å, and ultraviolet, in turn, merges into visible light, with a range of 4000 to 8000 Å (that's Angstrom).

Infrared heat waves are next in the spectrum and merge into microwave radio frequencies between 1 million and 4 million Å. From the latter figure, which equals 0.4 mm (0.016 in), to about 15,000 m (about 49,200 ft), the spectrum consists of the various lengths of radio waves; beyond the radio range it extends into the low frequencies of wavelengths measured in ten thousands of kilometers.

Ionizing radiation has different penetrating properties that are important in the study and use of radioactive materials. Naturally occurring alpha rays are stopped by the thickness of a few sheets of paper or a rubber glove. Beta rays are stopped by a few centimeters of wood. Gamma rays and X rays, depending on their energies, require thick shielding of a heavy material such as iron, lead, or concrete.

The spectrum, a rainbow-like series of colors, in the order violet, blue, green, yellow, orange, and red, produced by splitting a composite light, such as white light, into its component colors . Indigo was formerly recognized as a distinct spectral color. The rainbow is a natural spectrum, produced by meteorological phenomena. A similar effect can be produced by passing sunlight through a glass prism. The first correct explanation of the phenomenon was advanced in 1666 by the English mathematician and physicist Sir Isaac Newton.

The following might answer what you really are asking:
When a ray of light passes from one transparent medium, such as air, into another, such as glass or water, it is bent; upon reemerging into the air, it is bent again. This bending is called refraction; the amount of refraction depends on the wavelength of the light. Violet light, for example, is bent more than red light in passing from air to glass or from glass to air. A mixture of red and violet light is thus dispersed into the two colors when it passes through a wedge-shaped glass prism. A device for producing and observing a spectrum visually is called a spectroscope; a device for observing and recording a spectrum photographically is called a spectrograph; a device for measuring the brightness of the various portions of spectra is called a spectrophotometer; and the science of using spectroscopes, spectrographs, and spectrophotometers to study spectra is called spectroscopy. For extremely accurate spectroscopic measurements, an interferometer is used. During the 19th century, scientists discovered that beyond the violet end of the spectrum, radiations could be detected that were invisible to the human eye but that had marked photochemical action; these radiations were termed ultraviolet Similarly, beyond the red end of the spectrum, infrared radiations were detected that, although invisible, transmitted energy, as shown by their ability to raise the temperature of a thermometer (see Infrared Radiation). The definition of spectrum was then revised to include these invisible radiations, and has since been extended to include radio waves beyond the infrared, and X rays and gamma rays beyond the ultraviolet (see Radioactivity; X Ray).

The term spectrum is often loosely applied today to any orderly array produced by analysis of a complex phenomenon. A complex sound such as noise, for example, may be analyzed into an audio spectrum of pure tones of various pitches. Similarly, a complex mixture of elements or isotopes of different atomic weights can be separated into an orderly sequence called a mass spectrum in order of their atomic weights Spectroscopy has not only provided an important and sensitive method of chemical analysis, but has also been the chief tool for discoveries in the apparently unrelated fields of astrophysics and atomic theory. In general, changes in motions of the outer electrons of atoms produce spectra in the visible, infrared, and ultraviolet regions. Changes in motions of the inner electrons of heavy atoms produce X-ray spectra. Changes in the configurations of the nucleus of an atom produce gamma-ray spectra. Changes in the configurations of molecules produce visible and infrared spectra.

Different colors of light are similar in consisting of electromagnetic radiations that travel at a speed of approximately 300,000 km per sec (about 186,000 mi per sec). They differ in having varying frequencies and wavelengths, the frequency being equal to the speed of light divided by wavelength. Two rays of light having the same wavelength also have the same frequency and the same color. The wavelength of light is so small that it is conveniently expressed in nanometers (nm), which are equal to one-billionth of a meter. The wavelength of violet light varies from about 400 to 450 nm, and of red light from about 620 to 760 nm, or from about 0.000016 to 0.000018 in for violet, and from 0.000025 to 0.000030 in for red.

Light, form of energy visible to the human eye that is radiated by moving charged particles. Light from the sun provides the energy needed for plant growth and plants convert the energy in sunlight into storable chemical form through a process called photosynthesis. Petroleum, coal, and natural gas are the remains of plants that lived millions of years ago, and the energy these fuels release when they burn is the chemical energy converted from sunlight. When animals digest the plants and animals they eat, they also release energy stored by photosynthesis. Scientists have learned through experimentation that light behaves like a particle at times, and like a wave at other times. The particlelike features are called photons. Photons are different from particles of matter in that they have no mass and always move at the constant speed of 300,000 km/sec (186,000 mi/sec). When light diffracts, or bends slightly as it passes around a corner, it shows wavelike behavior. The waves associated with light are called electromagnetic waves because they consist of changing electric and magnetic fields.

To understand the nature of light and how it is normally created, it is necessary to study matter at its atomic level. Atoms are the building blocks of matter, and the motion of one of their constituents, the electron, leads to the emission of light in most sources.

Light can be emitted, or radiated, by electrons circling the nucleus of their atom. Electrons can circle atoms only in certain patterns called orbitals, and electrons have a specific amount of energy in each orbital. The amount of energy needed for each orbital is called an energy level of the atom. Electrons that circle close to the nucleus have less energy than electrons in orbitals farther from the nucleus. If the electron is in the lowest energy level, then no radiation occurs despite the motion of the electron. If an electron in a lower energy level gains some energy, it must jump to a higher level, and the atom is said to be excited. The motion of the excited electron causes it to lose energy, and it falls back to a lower level. The energy the electron releases is equal to the difference between the higher and lower energy levels. The electron may emit this quantum of energy in the form of a photon. Each atom has a unique set of energy levels, and the energies of the corresponding photons it can emit make up what is called the atom's spectrum. This spectrum is like a fingerprint by which the atom can be identified. The process of identifying a substance from its spectrum is called spectroscopy. The laws that describe the orbitals and energy levels of atoms are the laws of quantum theory. They were invented in the 1920s specifically to account for the radiation of light and the sizes of atoms.

Electromagnetic waves, The waves that accompany light are made up of oscillating, or vibrating, electric and magnetic fields, which are force fields that surround charged particles and influence other charged particles in their vicinity. These electric and magnetic fields change strength and direction at right angles, or perpendicularly, to each other in a plane (vertically and horizontally for instance). The electromagnetic wave formed by these fields travels in a direction perpendicular to the field's strength (coming out of the plane). The relationship between the fields and the wave formed can be understood by imagining a wave in a taut rope. Grasping the rope and moving it up and down simulates the action of a moving charge upon the electric field. It creates a wave that travels along the rope in a direction that is perpendicular to the initial up and down movement.

Because electromagnetic waves are transverse—that is, the vibration that creates them is perpendicular to the direction in which they travel, they are similar to waves on a rope or waves traveling on the surface of water. Unlike these waves, however, which require a rope or water, light does not need a medium, or substance, through which to travel. Light from the sun and distant stars reaches the earth by traveling through the vacuum of space.

The waves associated with natural sources of light are irregular, like the water waves in a busy harbor. Scientists think of such waves as being made up of many smooth waves, where the motion is regular and the wave stretches out indefinitely with regularly spaced peaks and valleys. Such regular waves are called monochromatic because they correspond to a single color of light.

The wavelength of a monochromatic wave is the distance between two consecutive wave peaks. Wavelengths of visible light can be measured in meters or in nanometers (nm), which are one billionth of a meter (or about 0.4 ten-millionths of an inch). Frequency corresponds to the number of wavelengths that pass by a certain point in space in a given amount of time. This value is usually measured in cycles per second, or Hertz (Hz). All electromagnetic waves travel at the same speed, so in one second, more short waves will pass by a point in space than will long waves. This means that shorter waves have a higher frequency than longer waves. The relationship between wavelength, speed, and frequency is expressed by the equation: wave speed equals wavelength times frequency, or

	c = lf

Each different frequency or wavelength of visible light causes our eye to see a slightly different color. The longest wavelength we can see is deep red at about 700 nm. The shortest wavelength humans can detect is deep blue or violet at about 400 nm. Most light sources do not radiate monochromatic light. What we call white light, such as light from the sun, is a mixture of all the colors in the visible spectrum, with some represented more strongly than others. Human eyes respond best to green light at 550 nm, which is also approximately the brightest color in sunlight at the earth's surface.

Polarization refers to the direction of the electric field in an electromagnetic wave. A wave whose electric field is oscillating in the vertical direction is said to be polarized in the vertical direction. The photons of such a wave would interact with matter differently than the photons of a wave polarized in the horizontal direction. The electric field in light waves from the sun vibrates in all directions, so direct sunlight is called unpolarized. Sunlight reflected from a surface is partially polarized parallel to the surface. Polaroid sunglasses block light that is horizontally polarized and therefore reduce glare from sunlight reflecting off horizontal surfaces.

Photons may be described as packets of light energy, and scientists use this concept to refer to the particlelike aspect of light. Photons are unlike conventional particles, such as specks of dust or marbles, however, in that they are not limited to a specific volume in space or time. Photons are always associated with an electromagnetic wave of a definite frequency. In 1900 the German physicist Max Planck discovered that light energy is carried by photons. He found that the energy of a photon is equal to the frequency of its electromagnetic wave multiplied by a constant called h, or Planck's constant. This constant is very small because one photon carries little energy. Using the watt-second, or Joule, as the unit of energy, Planck's constant is 6.626 x 10-20 (a decimal point followed by 19 zeros and then the number 6626) Joule-seconds in exponential notation. The energy consumed by a one watt lightbulb in one second, for example, is equivalent to two and a half million trillion photons of green light. Sunlight warms one square meter at the top of the earth's atmosphere at noon at the equator with the equivalent of about 14 100-watt lightbulbs. Light waves from the sun, therefore, produce a very large number of photons.

Sources of light differ in how they provide energy to the charged particles, such as electrons, whose motion creates the light. If the energy comes from heat, then the source is called incandescent. If the energy comes from another source, such as chemical or electrical energy, the source is called luminescent (see Luminescence).

In an incandescent light source, hot atoms collide with each other. These collisions transfer energy to some electrons, boosting them into higher energy levels. As the electrons release this energy, they emit photons. Some collisions are weak and some are strong, so the electrons are excited to different energy levels and photons of different energies are emitted. Candle light is incandescent and results from the excited atoms of soot in the hot flame. Light from an incandescent light bulb comes from excited atoms in a thin wire called a filament that is heated by passing an electric current through it.

The sun is an incandescent light source, and its heat comes from nuclear reactions deep below its surface. As the nuclei of atoms interact and combine in a process called nuclear fusion, they release huge amounts of energy. This energy passes from atom to atom until it reaches the surface of the sun, where the temperature is about 6000° C (11,000° F). Different stars emit incandescent light of different frequencies—and therefore color— depending on their mass and their age.

All thermal, or heat, sources have a broad spectrum, which means they emit photons with a wide range of energies. The color of incandescent sources is related to their temperature, with hotter sources having more blue in their spectra, or ranges of photon energies, and cooler sources more red. About 75 percent of the radiation from an incandescent light bulb is infrared. Scientists learn about the properties of real incandescent light sources by comparing them to a theoretical incandescent light source called a black body. A black body is an ideal incandescent light source, with an emission spectrum that does not depend on what material the light comes from, but only its temperature. A luminescent light source absorbs energy in some form other than heat, and is therefore usually cooler than an incandescent source. The color of a luminescent source is not related to its temperature. A fluorescent light is a type of luminescent source that makes use of chemical compounds called phosphors. Fluorescent light tubes are filled with mercury vapor and coated on the inside with phosphors. As electricity passes through the tube, it excites the mercury atoms and makes them emit blue, green, violet, and ultraviolet light. The electrons in phosphor atoms absorb the ultraviolet radiation, then release some energy to heat before emitting visible light with a lower frequency. Phosphor compounds are also used to convert electron energy to light in a television picture tube. Beams of electrons in the tube collide with phosphor atoms in small dots on the screen, exciting the phosphor electrons to higher energy levels. As the electrons drop back to their original energy level, they emit some heat and visible light. The light from all the phosphor dots combines to form the picture. In certain phosphor compounds, atoms remain excited for a long time before radiating light. A light source is called phosphorescent if the delay between energy absorption and emission is longer than one second. Phosphorescent materials can glow in the dark for several minutes after they have been exposed to strong light.

The aurora borealis and aurora australis (northern and southern lights) in the night sky in high latitudes are luminescent sources. Electrons in the solar wind that sweeps out from the sun become deflected in the earth's magnetic field and dip into the upper atmosphere near the north and south magnetic poles. The electrons then collide with atmospheric molecules, exciting the molecules' electrons and making them emit light in the sky. Chemiluminescence occurs when a chemical reaction produces molecules with electrons in excited energy levels that can then radiate light. The color of the light depends on the chemical reaction. When chemiluminescence occurs in plants or animals it is called bioluminescence. Many creatures, from bacteria to fish, make light this way by manufacturing substances called luciferase and luciferin. Luciferase helps luciferin combine with oxygen, and the resulting reaction creates excited molecules that emit light. Fireflies use flashes of light to attract mates, and some fish use bioluminescence to attract prey, or confuse predators.

Not all light comes from atoms. In a synchrotron light source, electrons are accelerated by microwaves and kept in a circular orbit by large magnets. The whole machine, called a synchrotron, resembles a large artificial atom. The circulating electrons can be made to radiate very monochromatic light at a wide range of frequencies.

For each way of producing light there is a corresponding way of detecting it. Just as heat produces incandescent light, for example, light produces measurable heat when it is absorbed by a material. Human vision works on a similar principle. Light of different frequencies causes different chemical changes in the eye. The chemical action generates nerve impulses that our brains interpret as color, shape, and location of objects.

Light behavior can be divided into two categories: How light interacts with matter and how light travels, or propagates through space or through transparent materials. The propagation of light has much in common with the propagation of other kinds of waves, including sound waves and water waves.

Refraction Refraction is the bending of light when it passes from one kind of material into another. Because light travels at a different speed in different materials, it must change speeds at the boundary between two materials. If a beam of light hits this boundary at an angle, then light on the side of the beam that hits first will be forced to slow down or speed up before light on the other side hits the new material. This makes the beam bend, or refract, at the boundary. Light bouncing off an object underwater, for instance, travels first through the water and then through the air to reach an observer's eye. From certain angles an object that is partially submerged appears bent where it enters the water because light from the part underwater is being refracted.

The refractive index of a material is the ratio of the speed of light in empty space to the speed of light inside the material. Because light of different frequencies travels at different speeds in a material, the refractive index is different for different frequencies. This means that light of different colors is bent by different angles as it passes from one material into another. This effect produces the familiar colorful spectrum seen when sunlight passes through a glass prism. The angle of bending at a boundary between two transparent materials is related to the refractive indexes of the materials through Snell's Law, a mathematical formula that is used to design lenses and other optical devices to control light.

Reflection Reflection also occurs when light hits the boundary between two materials. Some of the light hitting the boundary will be reflected into the first material. If light strikes the boundary at an angle, the light is reflected at the same angle, similar to the way balls bounce when they hit the floor. Light that is reflected from a flat boundary, such as the boundary between air and a smooth lake, will form a mirror image. Light reflected from a curved surface may be focused into a point, a line, or onto an area, depending on the curvature of the surface.

Scattering Scattering occurs when the atoms of a transparent material are not smoothly distributed over distances greater than the length of a light wave, but are bunched up into lumps of molecules or particles. The sky is bright because molecules and particles in the air scatter sunlight. Light with higher frequencies and shorter wavelengths is scattered more than light with lower frequencies and longer wavelengths. The atmosphere scatters violet light the most, but human eyes do not see this color, or frequency, well. The eye responds well to blue, though, which is the next most scattered color. Sunsets look red because when the sun is at the horizon, sunlight has to travel through a longer distance of atmosphere to reach the eye. The thick layer of air, dust and haze scatters away much of the blue. The spectrum of light scattered from small impurities within materials carries important information about the impurities. Scientists measure light scattered by the atmospheres of other planets in the solar system to learn about the chemical composition of the atmospheres.

Planck's theory remained mystifying until Einstein showed how it could be used to explain the photoelectric effect, in which the speed of ejected electrons was related not to the intensity of light, but to its frequency. This was consistent with Planck's theory, which suggested that a photon's energy was related to its frequency. During the next two decades scientists recast all of physics to be consistent with Planck's theory. The result was a picture of the physical world that was different from anything ever before imagined. Its essential feature is that all matter appears in physical measurements to be made of quantum bits, which are something like particles. Unlike the particles of Newtonian physics, however, a quantum particle cannot be viewed as having a definite path of movement that can be predicted through laws of motion. Quantum physics only permits the prediction of the probability of where particles may be found. The probability is the squared amplitude of a wave field, sometimes called the wave function associated with the particle. For photons the underlying probability field is what we know as the electromagnetic field. The current world view that scientists use, called the Standard Model, divides particles into two categories: fermions (building blocks of atoms, such as electrons, protons, and neutrons), which cannot exist in the same place at the same time, and bosons, such as photons, which can Bosons are the quantum particles associated with the force fields that act on the fermions. Just as the electromagnetic field is a combination of electric and magnetic force fields, there is an even more general field called the electroweak field. This field combines electromagnetic forces and the weak nuclear force. The photon is one of four bosons associated with this field. The other three bosons have large masses and decay, or break apart, quickly to lighter components outside the nucleus of the atom.

So I hope that helps.

Please feel free to ask me if that is not what you asked. And I perhaps misunderstood your question.

Here's some reading material I suggest you check out at your local libary..They can find the books for you:

Hope, Augustine and Walch, Margaret. The Color Compendium. Van Nostrand, 
1989. A one-volume encyclopedia of color appreciation and technology.

Nassau, Kurt. Physics and Chemistry of Color: The Fifteen Causes of Color. 
Wiley, 1983. Thorough; 


Rossotti, Hazel. Colour: Why the World Isn't Grey. Princeton, 1985. 
Requires only a little science.

Wasserman, G. S. Color Vision: An Historical Introduction. Wiley, 1978. 
Comprehensive study on how colors are seen, with explanatory theories.