Glossary on color

X-Rite and Labomat bring you a Color Management Glossary that contains over 1000 color-related terms and has been written to help you better understand the impact of color on your vision and workflow . From the fundamentals of color and light to expressions related to printing and industry, this glossary is very rich. Search for the term you are interested in below for its definition.

at*

Red / green coordinate in the CIE L * a * b * color space. A positive a * value indicates red coloration while a negative a * value is reflected by a greenish color.

Absolute colorimetric rendering intent

Rendering intent that keeps colors that fall within the gamut and crop colors that fall outside the gamut. This method preserves the white point, which may sound interesting, but can actually cause color deviations in the images. Absolute color intent is typically used for proofing. Rare, however, are the photographers who use it.

Absolute white

In theory, a material that perfectly reflects all light energy, at all wavelengths of the visible spectrum. In practice, a solid white showing known spectral reflectance data and used as a reference white for all absolute reflectance measurements. When calibrating a spectrophotometer, a white calibration ceramic is often measured and used as the absolute reference white.

Absorb (Absorption)

Dissipation of the energy of electromagnetic waves in other forms (heat, for example) as a result of its interaction with matter; decrease in the directional transmittance of incident radiation, resulting in a change or conversion of the energy absorbed.

Absorbance

“Ability of a medium to stop light. »The higher the value, the more light the sample absorbs. The values generally range from 0 to 3.0. Mathematically, absorbance is calculated using the following formula: A = log10 (1 / T) where T is the transmittance, expressed as a decimal number between 0 and 1 (for example, 0 , 5 R is equivalent to a reflectance of 50 %). This same equation is used to calculate density in applications related to graphic arts and photography.

Achromatic color

Colorless light, which produces a neutral black, gray or white color without tint.

Adaptation

The ability of the eye to adapt to different light sources or different levels of brightness. This phenomenon allows the visual system to adjust its sensitivity to different lighting conditions.

Additive color

Addition of primary colors to produce a multitude of colors. The most frequently used additive colors relate to the RGB (red, green, blue) model, which is used by computer screens to produce their display, and by scanners and digital cameras to capture images.

Additive synthesis

Process of combining the lights of the three primary colors (red, green and blue) in order to obtain colors. For example, Green + Red = Yellow, Red + Blue = Magenta, and Blue + Green = Cyan.

Additive primary colors

Light red, green and blue colors. The combination of the three additive primary colors at an intensity of 100 % produces white light. Their association with other intensities results in a gamut of different colors. Two primary colors combined with 100 % generate a subtractive primary color: Red at 100 % + Green to 100 % = Yellow, Red at 100 % + Blue to 100 % = Magenta, Green at 100 % + Blue to 100 % = Cyan.

Addressable resolution

Maximum resolution of a device.

Adobe® Acrobat®

Adobe software application used to create and view Portable Document Format (PDF) files. PDF files allow others to view a document exactly as it was designed, without necessarily having the software or fonts used to create the original file.

Adobe® Creative Suite®

A collection of graphic design, video editing, and web development applications developed by Adobe Systems, including Photoshop®, Illustrator®, Acrobat®, InDesign®, and Bridge to manage all loaded Creative Suite applications.

Air-brush

Software tool included in image editing programs that simulates the effect of a mechanical airbrush.

Aliasing

A visual effect characterized by contours having a staircase shape, which occurs in a low resolution image and which may be caused by improper sampling or processing of the image. Another term used: "aliasing".

Ambient light

Natural or mechanical light available in a room. Ambient light affects how colors appear on the screen and in the printed product. This factor must therefore be taken into account when evaluating the color.

American National Standards Institute (ANSI)

US federal agency that oversees the standardization of computer systems for business and communications purposes. The COBOL, FORTRAN, and C programming languages are all ANSI standards.

Angle of incidence

The angle at which a light beam strikes the surface of an object relative to the perpendicular to the surface of the object in question.

Reflection angle

The angle at which a light beam is reflected from the surface of an object relative to the perpendicular to the surface of the object in question.

Viewing angle

The angle at which a sample is viewed relative to the perpendicular to the surface.

Anti-aliasing

Removal or smoothing of jagged contours using spreading or blending techniques.

Anti-buildup aerosol

Starch powder that is sprayed onto freshly printed sheets to prevent smearing or wet ink transfer to the reverse side of the sheet directly above it.

Apparent color temperature

Appearance of the color of a light source in relation to the absolute color temperature of a black body (radiator) having the same color.

Appearance Manifestation of the nature of objects and materials through visual attributes such as size, shape, color, texture, gloss, transparency, opacity, etc.

Apple ColorSync

An independent color management system developed by Apple that provides essential services to achieve fast, consistent, and accurate color calibration, proofing and reproduction on a variety of input, output and display devices. ColorSync also provides an interface that allows you to establish color management settings for the entire system, allowing users to remember color settings for specific jobs and toggle between different settings.

Artifact

In digital graphics applications, unwanted visual anomalies or defects generated by an input or output device or software that degrades image quality.

Artificial daylight

Generic term that relates to light sources, often equipped with filters, which attempt to reproduce the chromatic and spectral distribution of daylight. A more specific definition of the light source is preferred.

ASCII (American Standard Code for Information Interchange)

A computer coding system that converts letters, numbers, and symbols into binary values that a computer can understand.

Aspect ratio

Relationship between horizontal and vertical measurements of an image. The horizontal value is placed first (for example: 3: 2).

Attribute

Distinctive characteristic of a sensation, perception or mode of appearance. Colors are often described by their attributes of hue, chroma (saturation), and lightness.

B

b *

Coordinate relating to yellow / blue in the CIE L * a * b * color space. A positive b * value indicates a yellow coloration while a negative b * value is reflected by a bluish color.

Banding

Inaccurate representation of color characterized by bands resulting from distinct and well-defined transitions between color ranges. Banding is usually caused by insufficient color or gray gamut in the output device's image processor, or insufficient information in the original scan.

Bandwidth

The ability of a data connection or network to carry data. The higher the value of the bandwidth, the faster the digital transmission. For analog transmission, bandwidth is measured in cycles per second or Hertz (Hz). In digital transmission, it is measured in bits per second (bps).

Beer-Lambert law

Describes the mathematical relationship between the absorption of light energy and the concentration of a dye or pigment.

Bit depth

Number of bits used to define the shade or color of each pixel in an image. A 1-bit image corresponds to a black and white image; an 8-bit grayscale image produces 256 shades of gray; an 8-bit color image generates 256 colors; and a 24-bit image refers to an image containing more than 16 million colors (8 bits for red, 8 bits for blue and 8 bits for green).

Bitmap (BMP)

An image file format consisting of a rectangular grid of pixels or dots, typically used on Microsoft Windows and OS / 2 operating systems. This format is supported by a variety of applications and applies RLE lossless compression.

Bits per pixel (bpp)

Number of bits used to describe the color or intensity of a pixel. For example, using 8 bits to store a value belonging to the RGB color model allows 3 bits for the value of red, 3 bits for the value of green, and 2 bits for the blue. If blue is assigned to a smaller gamut, it is because the human eye contains fewer blue cones and is therefore less sensitive to variations in this color.

Bits per second (bps)

A measure of data transmission rates, relating to the number of bits passing through a certain point in one second.

Black

Color that is produced when an object absorbs all wavelengths from the light source.

Black body location (de Planck)

A set of dots on a chromaticity diagram representing the colors of perfect radiators associated with various chromatic temperatures.

Radiator (black body)

In theory, an object absorbing all the energy coming into contact with it.

Generation of black

Adding black ink to other process colors (cyan, magenta and yellow) when printing an image. This black is generally generated from two techniques: gray replacement (GCR) and sub-color removal (UCR).

Black dot

Darkest shade on the histogram of an image, associated with a value of 0, 0, 0. The black point is used to adjust the tonal range of the image. Ideally, it corresponds to a reflectance or neutral transmittance of 0 %.

Blanchet

Canvas and rubber element covering the cylinder of an offset press, which transfers ink from the plate to the paper.

Blanket hanging bar

Accessory of an offset press which helps to maintain the blanket cylinder.

Blanket cylinder

On an offset press, cylinder which transfers the printing areas of the plate onto the paper.

Lost funds

An image or inked area that extends beyond the cropped edge of a page.

Glare (blooming)

Visual effect caused by overexposing an image sensor to too much light, causing overflow to adjacent pixels. This “digital overexposure” can cause subject and / or color distortions.

Blurry

Smoothing the details of an image.

Proof or BAT

Evidence accepted by a creator and which is used as a benchmark to compare all subsequent impressions. Some printers require a signed proof before starting production.

Object frame

In graphics applications, smaller regularly shaped area including an object, usually rectangular.

Shine

Overall intensity of an image. The lower the brightness value, the darker the image. Conversely, the higher the value, the brighter the image.

Bronzing

A problem with some ink / paper combinations that is characterized by brownish reflections in inked areas that juxtapose with areas associated with little or no ink, resulting in total paper reflection. Another term used: "gloss differential".

VS

VS*

Chromaticity coordinate in the CIE L * C * h color space. A chroma value of 0 (zero) indicates a perfectly neutral color, while a higher C * value indicates a more saturated color.

Hidden

The portion of high-speed memory reserved for frequently used data.

Calibration

The second step in the color management process, calibration is intended to adjust a device to its own specifications in order to avoid color deviations over time. Calibration should be applied to devices whose color characteristics change frequently, such as displays (their phosphors lose gloss over time) or printers (the output may vary between inks and media).

Calibration bars

Tape consisting of color or tone patches, used to control the quality of a negative, proof, or printed output, or measured in calibration software to restore a printing device to known standards.

Camera Profile

Defines how a raw image is rendered by image processing software. Profiles accurately render the final color of a particular pixel, compared to the raw data of the original image. It is possible to adjust how the editing software interprets the camera color by using the controls on the camera calibration panel and saving the changes as a preset.

Creation ready to flash

Any work or creation ready to be submitted for prepress and printing.

Candela per square meter (cd / m2)

Luminance unit based on the candela, the international unit of luminous intensity, and the value in square meters of the area. Most consumer office LCD screens have a luminance of between 200 and 300 cd / m2.

Capture

Acquiring digital image information using an input device, such as a scanner or digital camera.

Channel

Component of a digital image carrying data relating to a color layer. A grayscale image has only one color channel, an RGB image has three, and a CMYK image has four. Combining all the channels creates a full color image.

Characterization

The third step in the color management process, characterization involves measuring the actual values of the RGB or CMYK colors of a device using a colorimeter or spectrophotometer, to determine its color reproduction characteristics.

Chrominance

Color attribute used in the Munsell color ordering system to indicate the degree of deviation of a gray of the same value. Attribute that correlates with saturation; the further the color is from the axis, the purer it is.

Chromatic

Color perceived with a tint, that is, neither white, nor gray, nor black.

Chromaticity

Quality of a color, independent of gloss.

Chromaticity diagram

In practical terms, a two-dimensional graphic on which a color can be plotted relative to its hue and chroma. The third dimension of this graph is the luminance factor, or lightness, which is independent of hue or chroma. The position of a point on this graph indicates roughly what color it is (red, green, blue, mauve, etc.) and what its saturation level is. However, this information should be interpreted with caution as the coordinates of neutral colors differ from one illuminant to another. It is therefore advisable to avoid associating the coordinates with the appearance, unless the illuminant is specified. The representation of all the colors has a characteristic horseshoe shape.

Clipboard

Area of memory used to temporarily store pixels selected with the Cut, Copy and Paste commands.

CIE (International Commission on Illumination)

The International Commission on Illumination (or CIE) represents the competent international authority with regard to light, lighting, color and chromatic spaces. Succeeding the International Commission of Photometry, it was founded in 1913 and is currently based in Vienna, Austria.

CIE colorimetry

Color measurement according to the spectral reactivity of a CIE standardized observer.

CIELab (CIELAB, L * a * b *)

Uniform color space (the opposite of the color gamut) in which the colors lie in a three-dimensional system of rectangular coordinates. The three dimensions are lightness (L *), red / green tint (a *), and yellow / blue tint (b *). The CIELab space is one of the current recommendations of the CIE. This color space is based on the Adams-Nickerson cubic root function, adopted by the CIE in 1976 to measure minor color differences. Pronounced "si-lab". Another term used: "L * a * b *".

CIE Standard Illuminants

CIE has characterized several standard illuminants, designated by the letters "A", "B", "C" and "D", and published standard spectral power distribution curves to characterize the color of light of each. Illuminant A is designed to simulate the incandescent light of household bulbs. Illuminant D is designed to simulate natural light from two different spectral distributions. D50 represents light at a temperature of 5000 K and D65 represents light at a temperature of 6500 K. Standard viewing conditions applied in the graphic arts industry specify white light of 5000 K.

CIE Standard Observer

Observer data for a 2 degree field of view, adopted by the CIE in 1931 to represent the response of the average human eye adapted to an equivalent energy spectrum. An additional observer using a 10 degree field of view was defined in 1964.

CIE trichromatic components

In an additive trichromatic synthesis, required quantity of the three components necessary to match a color. In the CIE system, these components are designated by the letters X, Y and Z. The illuminant and standard observer used must be specified. Otherwise, the match is based on the following hypothetical values: CIE normalized observer 2 ° (1931) and illuminant C.

CIELCh

Uniform color space (the opposite of the color gamut) in which the colors lie in a three-dimensional system of polar coordinates. The three dimensions are brightness (L *), chroma (C *) and tint angle (h). The CIELCh space is one of the current recommendations of the CIE. To pronounce it, just spell the different letters.

CIE xy chromaticity diagram

Two-dimensional graph showing the chromaticity coordinates, where x is the abscissa and y is the ordinate, and which illustrates the spectral locus (chromaticity coordinates of monochromatic light, 380-770 nm). This diagram has many properties useful for comparing the colors of bright and non-luminous materials.

Clipping

An effect that occurs when all values lighter and darker relative to a specific tone are converted to white and black, respectively. The clipping may be due to a lack of contrast. It can also occur when certain gray values are lost or compressed into the perfect white or perfect black range.

CMC

Also referred to as CMC (l: c). Color difference formula based on CIELCh color space (the opposite of color gamut), in which the equivalent total difference values represent the equivalent visual differences, regardless of color.

CMYK (Cyan, Magenta, Yellow, Black)

The three primary colors of the subtractive color model used in color printing. In theory, the combination of pure CMY inks should produce black. In real life black must be added to achieve a full color gamut.

CMYK printer

Printer that uses the colors Cyan, Magenta, Yellow and Black to reproduce images on media. Most printers that work with a PostScript RIP are CMYK printers. This means that the RIP accepts RGB, LAB, or CMYK input data and then converts it to CMYK for printing.

Varnishing / Coating

A method of treating a support for accepting inkjet inks. Application of a thin coating intended to offer protection against UV-induced discoloration, smudging and fingerprints, and which can sometimes extend the life of the print since the discoloration is mainly due to the visible light.

Curl

Wrinkled or puckered appearance of the paper that occurs when ink absorption thresholds are exceeded, or a printing defect typically characterized by distorting puckering on the paper often caused by excessive ink loads or moisture.

Color

Visual perception created when light of various wavelengths in the range 400-700 nm approximately is detected by eye receptors and processed by the brain.

Color adjustment

In a printing process, adjustment of an initial color according to the determined standard. This setting should be checked regularly due to frequent changes.

Ability to color

Ability to work with and understand color. This is the fruit of both innate talents and experience.

Chromatic attribute

Three-dimensional characteristic of the appearance of an object. One dimension generally defines luminosity, while the combination of the other two relates to chromaticity.

Color balance

Ability to reproduce all the colors in a scene with an acceptable standard.

Color calibration

A method using a software and / or hardware component to adjust and coordinate colors between two or more digital devices. Color calibration systems typically compare the color profiles of different devices and convert a color model into a device independent language.

Color dominant

Unwanted tint of a specific color observed in an image, which may be due to the input device, output device, or lighting conditions.

Color compression

Narrowing the color gamut of an original sample to match the color gamut that a device is capable of rendering or reproducing.

Chromatic constancy

Relative independence of the perceived color of an object from the chromatic changes induced by the light source.

Chromatic correction

Adjusting an image to correct color imbalances or the characteristics of the chosen output device.

Color curve

A graph showing color measurements and can be used to make color changes in an image. Adjustments made to the angle and slope of the curve result in color changes on the color channels of an image.

Color difference - Equations

Mathematical equations that calculate the magnitude of the difference between two colors.

Color Difference - Digital

The difference between the colorimetric coordinate values of two samples. Quantify the difference between two colors.

Color Difference - Visual

Difference between two colors perceived by the human eye. It is generally expressed in qualitative terms, such as "lighter", "darker", "redder", "greener", "bluer", "more yellow", "paler", etc.

Color prepress system (CEPS)

A digital system used to prepare color images for mechanical printing and which generally involves the separation of the color image into CMYK values.

Color gamut

Range of colors that a material can reproduce.

Color pallet

A table of color values that is used to convert colors from one color space to another to support input and output data from different types of equipment.

Color management

A process that helps to address variations in color workflows by creating data files that describe the characteristics of each digital device. This process ensures color matching between different devices: between a screen and a printer, between an original photo and a digital file, and even between two prints created on different media with different inks. The four stages of color management are: consistency, calibration, characterization, and conversion.

Color management system

A combination of software and / or hardware components used to produce accurate colorimetric results throughout a digital imaging process.

Color matching function

Relative amount of the three additive primary colors (red, green and blue) required to match the wavelengths of light.

Color measurement

A physical measurement of the light radiated, emitted or reflected by a sample under specific conditions, which is mathematically transformed into standard colorimetric terms. These terms can be correlated with visual evaluations of colors.

Color measurement scale

A system for numerically specifying the perceived attributes of a color.

Chromatic model

A method of specifying (positioning) color in a color space, usually using a coordinate system. Examples: the RGB model and the Munsell color ordering system.

Color management policy

Determines how the application handles color data when opening a document or importing an image. You can choose different policies for RGB and CMYK images, and specify in what context to display warning messages.

Color scheduling systems A method of communicating color based on the three-dimensional color space. For a color collection to constitute a color ordering system, it must represent all of the colors in a three-dimensional color space. Colors should follow a visual progression or logical relationship to each other. Any color introduced into the system must fit in in a logical sequence. A slight variation in an existing color should be able to be easily described in partial steps. The system should provide values that ensure easy communication even in the absence of a sample. And finally, the medium used to represent the system must be consistent and reproducible. One of the most well-known color ordering systems is the Munsell.

Color profile

Mathematical equation used to convert colors from one color space to another in order to bring the rendering of equipment as closely as possible. In the digital printing industry, the color profile is commonly used, in particular to characterize specific equipment (screen, printer, scanner, etc.) in order to allow the user to ensure color consistency across different devices. See also Color management.

Color proof

Full color print output, designed to allow print designers and buyers to approximate the color characteristics produced by a press.

Color Quality The quality or "color" of light is specified as a target and tolerance in the CIE color space, and expressed as a correlated color temperature. This is the correlation between the emitted color and a theoretical blackbody heated to a specified temperature, measured in Kelvin (K).

Color rendering index

A measure of the magnitude of chromatic changes to which objects are subjected when illuminated by a light source, relative to the color of those same objects when illuminated by a reference source of comparable color temperature.

Color reproduction The process of reproducing colors on different equipment. Two commonly used color reproduction methods are additive color mixing and subtractive color mixing.

Color separation

Production of a separate printing plate for each color of ink used to print an image. Four plates are used for process color separation: one plate for each color (cyan, magenta, yellow and black), plus an additional plate for each spot color.

Chromatic space

Three-dimensional mathematical model including all possible colors. These are the parts of the visible spectrum that can be reproduced, such as RGB colors for computer monitors, CMYK colors for printed output, and web-friendly colors for online renderings.

Converting color spaces

The process of transforming a color from the chromatic space of one device into another space, and which may require approximation in order to preserve the quality of the main colors in an image. The conversion attempts to create the best match between the instruments. If the original equipment has a wider color gamut than the final instrument, some colors will end up outside the latter's color space. These out-of-gamut colors occur almost with every conversion and are called “gamut difference”. The most common rendering intents include perceptual, relative, and absolute intents.

Color specification Tristimulus values, chromaticity coordinates, luminance value, or other color gamut values used to numerically denote a color in a specified color system.

Color specification systems A method of communicating colors between customers, designers and printers. The most common specification systems are Pantone and HKS, often used as color guides, swatches, or color libraries.

Color table

Color palette of an image that can count up to 256 colors in indexed color mode.

Color temperature

Scale used to specify the visible energy of various light sources, expressed in degrees Kelvin, and to establish a classification of light sources (from red to white-blue). For example, daylight at noon is 5500 Kelvin, colored blue and white, while a tungsten bulb produces an orange color and rises to approximately 3200 Kelvin.

Chromatic tolerance

Acceptable difference between standard (reference) color and a sample.

Dye

Substance coloring a material or mixture. They can be colored substances or pigments.

Mixture of dyes

Mixture of colored substances or pigments.

Colorimeter

A device that measures color through red, green, and blue filters, then converts the data into digital values in three-dimensional color spaces that closely represent human vision. Unlike a densitometer, filters are more closely correlated with the human visual response, and the electrical circuitry inside the instrument is designed to transform the measured data into colorimetric values relating to the three-dimensional color spaces used to represent vision. human.

Colorimetry

A method of measuring and quantifying the color of an object based on a standard light source and a standard model of human vision. Three types of colorimetry instruments are mainly used in the graphic arts. These are (in order of sophistication) densitometers, colorimeters and spectrophotometers.

Colourist

Person specialized in the art of color matching (dye formulation) and mastering the behavior of dyes with a particular material. The term "colorist" is of European origin.

Color matching function

Amount of the three primary colors required to accurately reflect the radiant flux of each wavelength.

Color quality

The quality or "color" of light is specified as a target and tolerance in the CIE color space, and expressed as a correlated color temperature. This is the correlation between the emitted color and a theoretical blackbody heated to a specified temperature, measured in Kelvin (K).

Color temperature

A measurement expressed in degrees indicating the shade of a specific type of light source. The color temperature is traditionally expressed in a unit of absolute temperature, namely the Kelvin (K).

Chromatic circle

Continuous representation of visible spectra, organized in a circle, where complementary colors, such as red and green, are positioned directly opposite each other.

Colourist

Person specialized in the art of color matching (dye formulation) and mastering the behavior of dyes with a particular material. The term "colorist" is of European origin.

Complimentary colors

Two colors which when combined produce a neutral gray. On the color wheel, complementary colors are located on the directly opposite axis, such as blue and yellow, red and green, etc.

Composite printer

Printer used to create a composite color image of a file, for proofing or final output.

Compression

The process of removing irrelevant information and restricting unnecessary space from a file to make the file smaller. Compression can cause loss and distortion, depending on the method used. The two types of compression are lossy compression and lossless compression.

Direct plate making (CTP)

In the prepress industry, use of a computer to make the plate. Process leading to faster and better results.

Conditional match

A set of samples that appear to match under a limited set of conditions, such as light source or viewing angle.

Consistency

The first step in the color management process, consistency is about making sure that the device involved in a color workflow (a monitor, scanner, or printer, for example) is able to reproduce color consistently. . See also Color management.

Your continuous

Image, like a photograph, containing gradual transitions between shades or colors. For printing purposes, continuous tone images are converted to dot patterns (halftones).

Contractual test

Basis of a contract between a printer and a customer, where the appearance of the contract proof must reproduce the appearance of the final printed output.

Contrast

In an image, tonal gradient between highlights, shadows and midtones. High contrast involves dark black and bright white. Medium contrast refers to a good difference between black and white, while low contrast refers to a soft difference in black and white values.

Conversion

The fourth step in the color management process, conversion involves rendering a color as accurately as possible between the input device and the output device. For example, if an image is captured using an RGB scanner, retouched in a design application, and then printed on a CMYK printer, it would need to be converted multiple times. This process takes place in a chromatic space independent of the instrument, called CIELAB or profile connection space.

Proximal color temperature

Temperature, expressed in degrees Kelvin, of a point at a blackbody locus that comes closest to the light source.

Blanket slip

In printing, imperfection resulting in a slight displacement of the blanket forwards in contact with the plate or the paper.

Trimming

In graphics applications, a digital or manual process of cutting out unwanted portions of an image.

Cutting marks

In graphics applications, thin and short lines used for final weed, indicating the trimmed size of the final printed output.

Cathode ray tube

Viewing tube used in most standard televisions and computer monitors. An electron beam directed towards the rear of the screen excites the phosphors inside the glass tube, which produces the display of the image.

Curves

Graphic tools in image manipulation software that allow the user to change the contrast and color values of an image.

Custom Profile

Profile (data characterizing a color input device, output device, or color space) that personalized to reflect a specific instrument, such as a digital camera, monitor, or printer.

Upholstery (covering)

Flexible elements consisting of a set of acetate film or paper sheets, inserted under the plate and the blanket to adjust the pressure between the rollers and ensure a clean print.

D

D65

CIE standard illuminant representing a color temperature of 6,504 Kelvin. Illuminant D65 is widely used as a standard white point for calibrating displays.

Mooring roller

On offset presses, rollers wetting the non-printing surfaces of the plate.

Wetting solution

In offset printing, liquid solution composed mainly of water, used to maintain the wetting of the non-printing surfaces of a plate in order to make them refractory to ink.

Daylight illuminants (CIE)

Series of spectral distribution curves based on natural daylight measurements recommended by the CIE in 1965. Values are defined for the wavelength range 300-830 nm. They are described in terms of correlated color temperature. The most important illuminant is D65, due to the proximity of its color temperature correlated to that of illuminant C, 6,774 K. Illuminant D75, which is more bluish than D65, and illuminant D55, more yellow than D65, are also used.

Decompression

The process of restoring data from a compressed file.

Delta (D)

Symbol used to indicate deviation or difference.

Absorbance delta

Difference in absorbance values, for each wavelength, between samples and standard. A positive absorbance delta means that the sample absorbs more light than the standard. A negative absorbance delta means that the sample absorbs less light than the standard.

Delta E *

∆E or DE. Generic term expressing the total color difference, used to indicate the total color difference for all uniform color spaces. The total color difference (Delta E) is a single number that defines the magnitude (size, degree, quantity) of the difference between two colors. This value does not indicate the nature of the color difference.

Delta Ecmc

Value developed by the Measurement Committee of the Society of Dyers and Colourists in Great Britain. The DEcmc value results in an equation based on an ellipse to calculate the DE values. It is positioned as an alternative to the rectangular coordinates of the CIE L * a * b * color space. The DEcmc value is closer to human vision when it comes to assessing the acceptability of the color difference.

Delta K / S

Difference in K / S values, for each wavelength, between samples and standard. A positive delta K / S means that the sample has a higher absorption / diffusion ratio than the standard. A positive delta K / S means that the sample has a lower absorption / scattering ratio than the standard.

Reflectance delta

Difference in reflectance values, for each wavelength, between samples and standard. A positive reflectance delta means that the sample reflects more light than the standard. A negative reflectance delta means that the sample reflects less light than the standard.

Transmittance delta

Difference in transmittance values, for each wavelength, between samples and standard. A positive transmittance delta means that the sample emits more light than the standard. A negative transmittance delta means that the sample emits less light than the standard.

Delta value

Conversational term relating to "colorimetric coordinate delta". Sometimes the simple term "delta" is used. For example, in CIELab calculations, Delta L *, Delta a * and Delta b * are all referred to as “CIELab delta values” or “CIELab deltas”. This term is used to facilitate oral communication.

Densitometer

Instrument used to measure color through red, green and blue filters, which are similar to those used for color separation. With filters, complementary colors appear darker. This is why densitometers are said to “see” in black and white.

Density (optical density)

Degree of opacity of an image. The higher the density, the darker the image. Solid ink density measurements are used to monitor ink on paper.

Descreening

Applying a controlled blur effect when scanning halftone images to obtain continuous tone images and reduce the “moiré” effect.

Desktop Color Separation

File format that includes four .eps files; one for each process color (namely cyan, magenta, yellow and black.

Color dependent on equipment

Color space (LAB) unique to a specific device and its color rendering capabilities.

Device profile

Mathematical equations or conversion tables used to transform colors in a common color space into colors corresponding to the specific color space of a device.

Equipment color independent

Color specifications based on an independent color model (RGB, CMYK), not the gamut of an output device.

Chromatic space independent of the equipment

Color space that can be used to describe all colors seen by the human eye, regardless of the dyes used to reproduce the colors on specific equipment.

Equipment-specific color space

Chromatic space whose definition is based on the way in which specific equipment reproduces color. RGB and CMYK are both equipment-specific color spaces.

Diffuse juxtaposition

A method used to print continuous tone images on a laser printer, in which grayscale information is represented by randomly positioned print dots.

Diffuse reflection

Reflection characterized by the emission of light energy in multiple directions, at or below the surface.

Diffuse transmission

Emission of light energy through a sample and subject to the laws of refraction.

Diffused light

Non-directional or radiated light.

Digital camera

Equipment capable of capturing image data into a digital file.

Digital Camera Profile

Profile describing the conversion of the digital camera specific RGB space to the CIELab system. The test chart determines which colors from the original will be converted to the specific RGB colors of the digital camera. However, since a test chart only covers part of the digital camera's color gamut, the characterization software's job is to provide a description of colors outside of the camera's gamut.

Digital color printing

Non-impact printing technology where digital data is rendered, pixel by pixel, on inkjet, thermal or electrostatic transfer, thermal sublimation and photographic printing equipment.

Digital halftone

Reproducing the color and spatial resolution of digital image data using a series of dots organized in a square pattern.

Digital imaging

Process of capturing, manipulating and rendering a final image, accomplished by digital systems.

Digital photo printing

Printing technique involving equipment that exposes photo paper to LED, laser or cathode light sources, in order to restore, pixel by pixel, data captured using a digital device.

Digital printer

Equipment capable of translating digital data into paper output. This term generally covers all digital output technologies, such as inkjet printing, electrostatic or thermal transfer, or laser photo printing.

Direct to press printing

Printing process allowing the elimination of film separations.

Screen Profile

Profile describing the color spaces of a camera and an image. The screen profile tells the color management system how to convert the colors in the image to colors that match the color space of the screen in question.

Juxtaposition

A process used by some output devices to simulate shades of gray or color variations, and employs a randomization technique that uses various sizes and shapes of groups of pixels, rather than an ordered matrix of halftone dots .

Dmax

Maximum density measurement (darkest black possible).

Dmin

Minimum density.

Fattening

Phenomenon that occurs when ink spreads beyond the intended coverage on a media during printing. Problem often caused by abnormal or excessive absorption by the substrate. Also refers to the dot enlargement that occurs during plate making or on a press, which is caused by wet ink pushing onto the paper and being absorbed by the paper, resulting in a darker appearance colors or shades.

Spacing

Distance between dots on a computer screen, typically 0.24-0.38mm. The closer together the dots, the sharper the image displayed on the screen.

Sub-sampling

Decreasing the resolution of an image resulting in loss of detail.

Dots per inch (dpi)

A measure of a printer's resolution, which indicates the number of dots of ink the printer is capable of producing over a distance of one inch (or 2.54 cm), either vertically or horizontal.

Pilot

A program that allows a hardware device to communicate with a computer.

Drum scanner

Type of optical scanner incorporating a rotating drum on which a flexible original document is mounted. With each rotation of the drum, the light emitted by the document is captured point by point, thanks to a photomultiplier tube detector.

Drying

Time required for an ink to stabilize.

Double tone

A two-color reproduction of a monochrome or grayscale image, printed using two plates to increase its tonal depth.

Dye

A colored substance that does not scatter light, but on the contrary absorbs and reflects certain wavelengths and emits others. The dyes are generally organic and soluble in water. There are also solvent dyes.

Thermal sublimation

Color printing technology that forms an image by transferring gaseous dyes to the receiving material using a thermal pilot.

Dynamic range

Exhaustive range of tones, from the lightest to the darkest.

E

Early binding production flow

Convert all colors into the final output space as soon as possible.

Effective resolution

Final appearance of a scan that has been enhanced to produce more data than the scanner can generate. This technique is performed by interpolation.

Eight-bit (8-bit) color

Color where each pixel contains eight bits, which represents 256 colors or shades of gray. A grayscale image is an example of 8-bit color.

Electromagnetic spectrum

Range covering all possible frequencies of electromagnetic radiation. Light is a special type of electromagnetic radiation visible and detected by the human eye, but this energy comes in a wide range of wavelengths. The basic unit used to measure the wavelength of electromagnetic waves is the micron. The wave spectrum is divided into different sections based on wavelength. The shortest waves are gamma rays, which exhibit wavelengths of the order of a thousandth of a micron or less. The longest waves are radio waves, which are associated with wavelengths of several kilometers. The visible range consists of the narrow portion of the spectrum, which ranges from 0.4 microns (blue) to 0.7 microns (red).

Electrostatic transfer

An imaging process using "toner" to produce an image, using controlled static charges. The print adheres to the loaded surfaces.

Ellipsoid

Solid where all planes are ellipses (close curves produced when a cone is cut by a plane obliquely at its axis).

Embedded profile

Profile defining the chromatic characteristics of an image. Embedded profiles can relate to RGB, CIELab, CMYK or grayscale spaces, and depend on the selected working color space or original equipment.

Emissive object

Object that emits light. The emission is usually caused by a chemical reaction, such as hot gases from the sun or the heated filament of a light bulb.

Emulsifying agent

Substance used to mix inks and which facilitates the dissolution of one liquid into another.

Encapsulated PostScript (EPS)

A metafile format developed by Adobe that supports both images and graphics based on bitmap or vector objects. This file format is supported by various applications and is frequently used to transfer files between applications. Compatible with RGB, CMYK and LAB color spaces, it is also often used to transmit files from one application to another and for color separation tasks.

Encryption

A method of encoding a file by means of software programs so that no one can access its content.