CTD 461 Lecture Notes - Lecture 5: Tungsten, Lab Color Space, Black Body
Chapter 9: Color
• Specified early in product development
• Color management systems combine digital information and physical samples
Color Theory
• Sensation, a result of physical modification of light by colorants as observed by the
human eye and interpreted by the brain
• Not an inherent property of a material, such as in mass
• For it to exist, 3 things are necessary
➢ Light source
➢ Substrate containing colorants
➢ A detection system
• Colorants are physical entities, such as dyes/pigments, which are applied to a substrate,
such as textile or apparel product, so it will be seen as having a particular color
➢ Color exists only in the mind of the beholder
Waves
• Form of energy represented by a series of crest and trough
• Wavelength distance from one crest to the next crest
• Measured in metric system
• Nanometer 1 x 10-9 meter
• Frequency—number of wave crests pass a certain point in one second
• Frequency increases, wavelength become shorter
• Amplitude—height of wave
• Speed of light approximately 186,000 miles/sec
• Electromagnetic spectrum—continuous range of frequencies and wavelengths of energy
• Visible light consists of radiation having wavelengths between about 400nm and 700nm
➢ Because of certain cells in the retina of the eye
➢ Rods and cones
➢ Contains pigments which interact with light if that particular wavelength range
• Infrared region wavelengths—longer than visible light; heat
• Ultraviolet region wavelengths—shorter than visible light
Schematic of the Human Eye
• Light—created by conversion of matter into energy; travels through space; converted to
chemical energy when absorbed by matter
• Rhodopsin—chemical in the eye; absorbs light; converts it to chemical energy and nerve
impulses when we see objects
• Visible light from various sources is perceived as white light
➢ Isaac Newton used a glass prism that showed that sunlight was actually made up
of a mixture of a large variety of light
Interaction of Light with Matter
• When light from a source contacts dense matter, there are a number of personalities
1. Light can be transmitted through the material, wholly/partially.
▪ Materials which transmit the most of the incident light are called
transparent
▪ Materials that are colorless and transparent transmit all the incident light
except for a small amount reflected on a surface
2. Light can be absorbed by the material if all the wavelengths are absorbed by the
material, it appeals black, and is said to be opaque
▪ Materials which transmit/scatter light are translucent
▪ Scatter most of incident light and transmit very little are opaque
▪ Wavelengths are reflected, material is white
▪ Contains colorants when can absorb certain wavelengths of the incident
light, then the unabsorbed wavelengths are reflected and materials
appear to have color associated with the reflected wavelength
▪ Visible light is generated by a variety of light sources, each of which has
its special power
▪ Sources include the sun, blackbodies, arc lamps, and fluorescent lamps,
which use glowing tungsten filaments, are a close approximately to a
blackbody radiating and 2854 degrees K
o A blackbody radiating at 6000 degrees K is a fair representative of
daylight
▪ Illuminants—are light defined by their special power distribution, which
may/may not be physically realized as sources
▪ Sources are the actual lights having measured spectral power
distributions
o Illuminants have specified power distribution
o All standard sources have corresponding illuminants, but not all
standard illuminants have corresponding sources
Standard Light Sources
• Color seen by observer dependent on light source
• Standardized light source—essential for color matching
• No single light source perfect for all applications and end uses; different sources satisfy
different needs
Part 2: Color Systems
• Number of systems have been devised for both describing/ordering perceived colors
• 3 parameters to characterize any particular color
➢ correspond to the 3 dimensions of the color space
Munsell Color System
• color—order system based upon steps of equal vision perception
1. Munsell hue—equality of a color which is described by the words red, blue, yellow,
and green
2. Munsell value—quality of color which is described as dark, light, etc.
▪ Relate to gray of similar lightness
3. Munsell Chroma—quality of color described the extent by which a color differs from
gray having the same value (saturation)
CIE System
• Color—order system not based on a collection of physical samples
Document Summary
Specified early in product development, color management systems combine digital information and physical samples. A detection system: colorants are physical entities, such as dyes/pigments, which are applied to a substrate, such as textile or apparel product, so it will be seen as having a particular color. Color exists only in the mind of the beholder. Because of certain cells in the retina of the eye. Contains pigments which interact with light if that particular wavelength range. Infrared region wavelengths longer than visible light; heat: ultraviolet region wavelengths shorter than visible light. Isaac newton used a glass prism that showed that sunlight was actually made up of a mixture of a large variety of light. Illuminants are light defined by their special power distribution, which may/may not be physically realized as sources: sources are the actual lights having measured spectral power distributions. Illuminants have specified power distribution: all standard sources have corresponding illuminants, but not all standard illuminants have corresponding sources.
