ASCII (American Standard Code for Information Interchange)
A file encoded in the industry-standard representation for
text. ASCII files can be read by most software programs.
ASCII Data File
A series of linearization or color patch measurements saved
in a standard ASCII text format.
Brightness
The lightness of a color or tone, regardless of hue or saturation.
Calibration
The process of adjusting the performance of input, display,
and output devices to a known state.
Characterization
The process of creating a custom profile for an input, display,
or output device by describing the unique gamut of each
device.
Chrominance
Exhibiting a color or a mixture of hue and saturation, independent
of luminance.
CIE
The Commission Internationale d’Eclairage (International
Commission on Illumination), an organization which has
determined many of the standards used in color measurement.
CIELAB (CIE L*a*b* or CIE Lab)
A color space based on CIE XYZ. The L* value represents
lightness, and a* and b* values are chromaticity coordinates.
CMYK
Cyan (C), magenta (M), yellow (Y), and black (K) are the
inks used in the printing process. A color model based on the
three subtractive colors cyan, magenta, and yellow. Printers
are generally CMYK devices.
Colorant
A dye, ink, or pigment that is used to give color to another
material.
Color cast
An overall color imbalance in an image.
Color gamut
The limited range of colors that can be reproduced by a
device or set of colorants. Color gamuts are device-specific.
Colorimeter
An instrument used to read or specify color by measuring the
amount of light transmitted or reflected in tristimulus values.
Color Management System (CMS)
A software system that ensures color consistency and repeatability
across all devices in a production workflow.
ColorSync
The Macintosh Operating System’s color management
resource for passing device-specific color profiles.
Color space
A mathematical model that is used to describe color in which
each color is represented by a point in space. Each color is
defined in terms of three numbers and plotted as a point in
space relative to three axes. RGB and CMYK are examples of
color spaces.
Color temperature
A measurement of the color of light in degrees Kelvin. The
lower the temperature the yellower the light appears. The
high temperatures appear bluer. 6500K represents a neutral
gray.
Contrast
The variation between the lightest and darkest areas in an
image.
CRT (cathode-ray tube)
The vacuum tube that is used as a display screen in computer
monitors and television sets.
Curve
A graph showing the relationship of input values to output
values.
DCS 2.0
DCS is an acronym for Desktop Color Separation. DCS is a
file format, based on the EPS file format, that is used to
exchange bitmap images between prepress applications. DCS
files must be printed with a PostScript printer.
Delta E (?E)
A computed value that represents how close two colors are to
each other. A difference of 1 ?E is used as a threshold of what
is perceptible to the human eye. A difference of 6 to 7 ?E is
considered acceptable in the printing industry.
Densitometer
An instrument that measures the ability of a surface to reflect
or transmit light.
Density
A computed number representing the ability of a transmissive
material to block light, or the ability of a reflective surface
to absorb light. The more light blocked or absorbed, the
higher the density. Density values range from approximately
0.05 to 2.5 for reflective targets and from 0.05 to 3.5 for
transmissive sources.
Drift
Small changes to a device that occur over time.
Dynamic range
The range of tones a device is capable of measuring, sensing,
or rendering.
Gamma
A number representing the gamma curve of a device. A
gamma of 1.0 represents a linear device. Gamma is associated
with contrast because increasing the gamma increases the
contrast in shadows and midtones which decreasing the contrast
in highlights.
Gamma curve
A plotted curve representing the relationship between input
and output tonal values for a device.
Gamut
The limited range of colors reproducible by a given device.
Gamut compression
The conversion of color coordinates from a color space with
a larger gamut to the coordinates of a color space with a
smaller gamut.
Gamut mapping
The conversion of color coordinates from one color space
into a second color space.
GCR (gray component replacement)
The replacement of some amount of CMY ink in a CMYK
pixel with sufficient black ink to restore the pixel to the original
appearance.
Gray balance
The balance between colorants required to produce neutral
grays with no color bias.
Grayscale
A tonal scale that represents the lightest white to the blackest
black, with intermediate shades of gray in between. A grayscale
is used as a guide to ensure proper calibration and unbiased
color balance settings.
HexachromeR
An ink system developed by PANTONE® which uses six
printing inks—cyan, magenta, yellow, black, and orange and
green (CMYK+OG).
Highlight
The lightest or brightest points in an image.
ICC (International Color Consortium)
A committee formed in 1993 to establish standards for electronic
color publishing.
ICC profile
Profile conforming to International Color Consortium profile
format standards.
Interpolation
A calculated value that falls between two values.
IT8
Industry standard test targets used to characterize input and
output devices.
Kelvin
A system of absolute temperature. For our purposes, the scale
is used for the expressing color temperature of the white
point of the light source in a computer monitor, and the
color temperature of the light source used to view images.
Lab (CIELAB or CIE L*a*b*)
A color space based on CIE XYZ. The L* value represents
lightness, and a* and b* values are chromaticity coordinates.
The Lab color space is used to measure reflective and transmissive
materials.
LCD (liquid-crystal display)
The display screen used in laptop computers and flat screen
monitors.
LCh (L*C*h)
A color space that is similar to Lab, but uses lightness,
chrominance, and hue coordinates.
Lightness
The variation of a hue along a range from white to black.
Linear device
A device in which input values consistently produce equivalent
output values across the entire tonal range. Most devices
are non-linear and require some correction to make them
linear.
Linearize
The process of making a device linear.
Linked profile
Combination of two CMYK output profiles, used to simulate
the output of a source device (usually a printing press) on a
destination device (usually a digital proofer).
Luminance
Luminance refers to the measurable aspect of brightness.
Luminance is a measurable quantity, while brightness is perceived.
An increase in luminance is usually perceived as an
increase in brightness. The relationship, however, is not linear.
Doubling luminance will not necessarily double perceived
brightness.
Mask
An image area that is protected from change.
Memory colors
Color representing familiar objects, such as blue sky, green
grass, and various skin tones.
Midtone
The middle range of tones in an image.
Multi-ink profile
An output profile that uses 5, 6, 7, or 8-colorants.
Neutral
An area of color containing no bias; white, gray, or black.
Paper white
The color of the paper on which a colorant is printed.
Phosphor
A substance which coats the inside of computer monitors
which glows when struck by certain wavelengths of radiation.
PostScript
A page description language developed by Adobe Systems.
Profile
A file containing data which describes how a device handles
or distorts colors. Profiles are used by a color-managed application
to correct the passage of color through the device.
Proof
A visual or hardcopy preview of the expected final results of a
printed piece. The visual preview is obtained on a color monitor.
A hardcopy preview may be a print from a digital printer
or a press proof.
Quarter tones
Tones falling between the shadows and midtones in an image
are called 3/4 tones. Tone between highlights and midtones
are known as 1/4 tones.
Reference file
A file that contains data against which other measurements
are compared.
Resolution
The number of discrete elements per unit of measure that
make up an image, or the number of imaging or sampling
units used in a device.
RIP (Raster Image Processor)
Software or hardware that converts digital image data to bitmap
or pixel format.
RGB
A color model based on the three additive primary colors of
light used in color reproduction — red (R), green (G), and
blue (B). Monitors, scanners, and film recorders are generally
RGB devices. RGB is a relative color space.
Saturation
The vividness or purity of a color. The color attribute characterized
by the absence or presence of a gray component.
Scanner
An electronic device for capturing the tonal and color characteristics
of images as digital data.
Shadow
The darkest areas in an image.
Spectrophotometer
An instrument used to describe or specify color by measuring
spectral data.
Specular highlight
A highlight lacking ink and brightly reflecting the light
source.
Spot color
Additional colorants used in multi-color (5, 6, 7, and 8-
color) printing.
Transformation
An algorithm (mathematical formula) which defines how
colors are converted from one color space to another.
UCR (under color removal)
Subtracting CMY colorants from dark areas and replacing it
with additional black as a means of saving ink on long press
runs and reducing ink in shadows.
TIFF (Tagged Image File Format)
A format for exchanging bitmap images between applications.
Scans are typically saved in TIFF format.
Tonal range
The maximum range of visible tones in an image.
USB (Universal Serial Bus)
USB is a multi-platform industry standard for connecting
computers and peripherals.
White balance
The balance between colorants required to produce neutral
gray with no color bias.
White point
The chromaticity of a light source, often described by referring
to it’s chromaticity coordinates or the color temperature
of the light source.

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