Glossary
Discover our glossary! Find out everything about color measurement, color standards and spectrophotometers. Simply explained, practical and to the point. Perfect for beginners and experts!
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a
- AbsorptionA portion of electromagnetic radiation strikes the sample and is converted into other energy states within the sample, thereby reducing the radiation intensity. The absorption value is proportional to the sample's thickness and the amount of absorbing substances. It is calculated from the... Mehr lesen
- Angle of IncidenceThe angle between the axis of the incident light and the perpendicular to the surface of the sample is called the angle of incidence. Mehr lesen
- APHA / APHA Colour NumberAPHA stands for the American Public Health Association. The APHA color number is a finely scaled measure used to determine the color of nearly colorless to pale yellow liquids. The terms "Hazen" or "Hazen color number" and "Platinum-Cobalt color number" (PtCo) are used interchangeably, as... Mehr lesen
- ASTM - American Society for Testing and MaterialsASTM stands for the American Society for Testing and Materials. ASTM publishes technical standards for testing and analytical procedures, such as color comparisons, and currently has more than 12,000 standards. These include standards like ASTM D 1500 (glass standards with defined transmission),... Mehr lesen
b
- BrightnessOne of the three parameters that together form the human perception of color. Along with hue and saturation, brightness describes how light or dark a product appears. Mehr lesen
c
- CIE 1976 L*a*b Colour SpaceThe CIE L*, a*, b* color space (from 1976) most closely corresponds to human color perception. Unlike the XYZ color space, it is equidistant and consists of the brightness axis L*, the red/green axis a*, and the yellow/blue axis b*. Based on the opponent color theory, the coordinates in the... Mehr lesen
- CIE, Commission Internationale de l'ÉclairageTranslated: International Commission on Illumination. It establishes global standards for color measurement and color definitions. Mehr lesen
- CIE Standard Colour Matching System and CIE Standard Colour ChartThe Tristimulus values can be normalized into the so-called standard color components or standard chromaticity values, x and y, as follows: x = X / (X + Y + Z) ; y = Y / (X + Y + Z); (z = Z / (X + Y + Z)) Since x + y + z = 1, z does not need to be explicitly calculated, because it is given by:... Mehr lesen
- CIE Standard IlluminantsThe CIE standard illuminants are artificial light sources defined by the CIE whose radiation closely approximates the CIE standard illuminants A, C, and D65.Standard illuminants are light types standardized by the CIE, each defined by a specific spectrum. The choice of an illuminant is used in... Mehr lesen
- CIE Standard Light SourcesArtificial light sources defined by the CIE, whose radiation closely approximates the CIE standard illuminants such as A, F, and D65. Mehr lesen
- CIE Standard ObserverThe CIE 2° and 10° standard observers refer to two different test configurations used to standardize human color perception for instrumental measurements. The goal of these tests was to determine the specific intensities of red, green, and blue light required to match the color impression of... Mehr lesen
- CIE Tristimulus SystemTo relate human color perception to the physical color stimulus, the CIE developed a color space in 1931 based on a coordinate system. This system was called the Yxy color space or the Tristimulus color space. The system was based on measurement values relative to an averaged observer with a 2°... Mehr lesen
- CMCThe CMC (Colour Measurement Committee of the Society of Dyers and Colourists of Great Britain) established an equation in 1984, based on LCh values. Its application area is primarily the textile industry, which is why, in addition to the factors of lightness and saturation, a "commercial factor"... Mehr lesen
- ColourColor is perceived by the human eye when light strikes a surface and is reflected. White light is partly reflected and partly absorbed. Depending on the amount of light reflected, we perceive a specific color. This process occurs in the brain after the eye (and its cones) are stimulated by... Mehr lesen
- Colour DetectionThe recognition of a rough color difference is also possible without a spectrophotometer, whether through a trained eye or with the help of color matching booths. The objective color impression, which provides comparable and precise values for industry, can only be made with standardized color... Mehr lesen
- Colour distanceColor distance quantifies the difference between two colors. It is often expressed through the ΔE value (Delta E), which measures the difference in the color coordinates of two colors in the color space. A ΔE value of 0 indicates no deviation, while higher values indicate greater differences.... Mehr lesen
- Colour DifferenceA comparison of a sample to the standard based on color difference data such as Delta E, Delta E*, Delta C, Delta C*, Delta E CMC, etc. If the color scale L*, a*, b* is used, the Delta values represent lighter/darker, red/green, or yellow/blue. If the LCh color scale is used, the values... Mehr lesen
- Colour ImpressionThe colour impression is created when only certain wavelengths are absorbed from white light. For example, if a sample absorbs light in the range of 520 to 570 nm, it will appear green to the human eye. Mehr lesen
- Colour MeasurementIn color measurement, color can be captured with numerical values using spectrophotometers or tristimulus colorimeters. This allows for the detection of subtle color nuances and the definition of a color impression. Important components in color measurement include: color space, light source,... Mehr lesen
- Colour Measurement InstrumentsFor industrial color measurement, either spectrophotometers or colorimeters are used. A spectrophotometer measures the remission values of visible light across the entire spectrum. With these values, the exact color location and color deviations can be defined. The most precise... Mehr lesen
- Colour NumberA color number is an index used for specific industrial applications, such as the Gardner color number or APHA for the pharmaceutical industry. Color numbers are pre-stored on the color measurement device according to standards. Using reference values, comparisons can be made until the exact... Mehr lesen
- Colour SensationThe cause of color sensation is the color stimulus, while the effect is the perception of color. According to the physicist Helmholtz, color sensation is defined by hue, saturation, and brightness. In the CIE L*, a*, b* color space, these are represented by the coordinates L* (for brightness),... Mehr lesen
- Colour SpaceA three-dimensional representation of all colors that can be represented in a color model. Examples include: CIE L*, a*, b*, CIE XYZ, CIE LCh, and Hunter L, a, b. Other color spaces include RGB, CMYK, LMS, and HSV. Mehr lesen
- Colour StimulusThe color stimulus is the cause of the perception and interpretation of color. It always originates from a light source and stimulates the retina of the human eye. A color stimulus refers to electromagnetic radiation that enters the eye and triggers color perception through direct stimulation... Mehr lesen
- ConesThe basis of colorimetry is the spectral absorption curve, which results from the stimulation of all three types of cones located in the central area of the retina. Cones are light-sensitive cells in the human retina that are responsible for color vision. There are three types of cones, each... Mehr lesen
d
- Delta E* /dE*, ?E*)Color deviations are expressed as Delta E* in the L*, a*, b* color space. The value is always calculated using the equation between two color locations.The smallest color difference that can still be perceived by the human eye is represented by a Delta E* value of 1. As the color deviation... Mehr lesen
e
- EBC Colour ValueA color value used to determine the color of beer and wort in the quality control of the brewing process. The EBC color value is a scale used to measure the color intensity of beer and wort, defined by the European Brewery Convention. It is determined photometrically from a standardized mash... Mehr lesen
- EP Colour number (according to Ph. Eur. 2.2.2)To check the product quality of yellowish to almost colorless liquids, 37 comparative solutions of the EP color number have been specially developed. These are used to determine the color quality of various liquid pharmaceutical products, concentrated liquid proteins or other liquids that may... Mehr lesen
- Equal SpacingDue to external influences, metamerism, and the individual condition of the observer, it can sometimes be difficult to achieve a consistent color impression. In industrial color measurement, tolerances are always discussed. When a fixed color distance, Delta E, is specified, it provides a... Mehr lesen
- EyeAs a sensory organ for the perception of light and color, the eye absorbs light stimuli through photoreceptors. These stimuli are processed by the brain into optical perception. The human eye contains rods in the retina for detecting light/dark contrasts and cones for color perception (blue,... Mehr lesen
f
- FDAThe FDA (Food and Drug Administration) is the U.S. government agency responsible for the approval of food and drug products. It is tasked with protecting public health by overseeing the safety, effectiveness, and quality of pharmaceuticals, food products, medical devices, cosmetics, tobacco... Mehr lesen
- FluorescenceThe property of absorbing light of shorter (invisible) wavelengths and emitting light of longer (visible) wavelengths. Example application: Fluorescent materials enhance the visibility of traffic signs, especially in poor visibility conditions. Mehr lesen
g
- Gardner Colour NumberThe Gardner Color Number describes samples such as oils, resins, and other chemicals. It is defined using glass standards with specified transmission and color characteristics, ranging from light yellow to red. Mehr lesen
- GeometryBei einem Farbmessgerät bezieht sich Geometrie auf die Art und Weise, wie Licht auf die Oberfläche eines Objekts trifft und reflektiert wird, sowie auf den Winkel, unter dem die Farbmessung erfolgt. Die Wahl der Geometrie beeinflusst die genaue Messung der Farbe, da verschiedene Oberflächen... Mehr lesen
- Gloss, Gloss TrapGloss affects the perception of a sample's color. Two objects with the same color can have different surfaces, such as matte/glossy or textured/smooth. To the human eye, they appear different, even though a color measuring device outputs the same values for the color definition. If the goal is... Mehr lesen
h
- HazeHaze refers to the cloudiness or scattering of light on a surface that reduces the clarity and transparency of a material. A high haze value indicates greater light scattering. Mehr lesen
- Hitching"Hitching" refers to the process of standardizing two color measurement devices so that they produce nearly the same values when measuring multiple samples. Mehr lesen
- Hue / Colour HueIn contrast to achromatic colors like white, gray, and black, which are considered colorless, a hue refers to sensory impressions that can be described as colors such as red, yellow, green, etc. Unlike achromatic colors like white, gray, and black, hues are associated with specific colors or... Mehr lesen
- Hunter L,a,b Colour SpaceThe HunterLab color space, developed by R.S. Hunter in 1948, is a three-dimensional, rectangular color space based on the theory of complementary colors. All colors visually perceived can be plotted or numerically represented within this rectangular L, a, b color space. The Hunter Lab color... Mehr lesen
i
- InterferenceInterference is a phenomenon in which two or more waves (e.g., light, sound, or water waves) overlap. This can result in the waves either reinforcing each other (constructive interference) or canceling each other out (destructive interference). In light, interference affects how colors or... Mehr lesen
l
- LightLight is the range of electromagnetic radiation visible to the human eye, extending from 380 nm to 780 nm. Light travels at approximately 300,000 km/s and is essential for visual perception. Mehr lesen
- Lovibond Colour NumberThe Lovibond® scale is based on 84 calibrated color standards made of glass, with varying optical densities in the colors Magenta (Red), Yellow, Blue, and Neutral, ranging from desaturated to fully saturated. The three primary colors and the neutral filters are combined until they match the... Mehr lesen
m
- MetamerismMetamerism describes the phenomenon where two colors appear identical under a specific light source, even though they have different compositions. However, under a different light source, they may appear different. Mehr lesen
- Metamerism IndexThe Metamerism Index is a measure of how strongly two colors are perceived differently under various light sources. A high index means that the colors significantly differ under changing light conditions, while a low index indicates that the colors remain similar even under varying light. Mehr lesen
n
- Nanometer (nm)A nanometer is a unit of length equal to one billionth of a meter (0.000000001 m). It is commonly used to measure very small lengths, such as the wavelengths of light. Mehr lesen
- Normal ObserverA "normal observer" refers to a recipient of radiation whose spectral sensitivity curves match the CIE standard spectral value curves. Mehr lesen
o
- ObjectIn the context of color measurement, an object is any material or surface whose color is measured or assessed, also referred to as a sample. This can include anything from textiles to paints to plastics, with the color potentially varying depending on lighting conditions, observation angle, or... Mehr lesen
- OpacityOpacity refers to the opacity of a material, or its ability to block or transmit light. A material with high opacity lets little to no light pass through, while a material with low opacity (such as glass) allows a lot of light to pass through. Mehr lesen
- Opponent-Process TheoryAn alternative proposal to the three-color theory by Karl Ewald Konstantin Hering, who suggested that three separate chemical processes occur in the retina, where the color pairs Blue-Yellow, Red-Green, and Black-White strive for balance.The opponent-process theory states that color perception... Mehr lesen
- OpticsOptics refers to the interaction of light with surfaces, influencing color, brightness, and phenomena such as interference and metamerism. Mehr lesen
p
- PolychromatorA polychromator is an optical device that splits light into different wavelengths (colors). It is commonly used in spectroscopy to break light into a spectrum, allowing for the analysis of material properties in relation to their color or light absorption Mehr lesen
- PrecisionPrecision refers to the accuracy and repeatability of measurements or results. A precise instrument provides the same or very similar values when repeated measurements are taken under the same conditions. Mehr lesen
q
- Quality Assurance, Quality Control, Quality ManagementActions and activities performed to ensure a quality requirement, such as consistent product quality. Quality Assurance (QA) involves measures to prevent defects, Quality Control (QC) is the inspection of products for defects, and Quality Management (QM) is the overall system for ensuring and... Mehr lesen
- Quality Attribute(Aalso known as a test attribute) A quality attribute is a characteristic used to assess the quality of a product, such as color, durability, or precision. Mehr lesen
r
- ReflectionAt a surface between two media with different refractive indices, incident waves are reflected back, and the refractive index of the medium is altered (e.g., light refraction changes). The following types of reflection are distinguished: Directed Reflection: On smooth, polished surfaces,... Mehr lesen
- Rosin Colour NumberThe Rosin Color Number measures the color of resins, particularly rosin. It indicates the intensity of the color of the resin, with higher values representing a more intense color. Mehr lesen
s
- Sample PreparationThe preparation of the sample plays a crucial role in obtaining precise measurement results. Temperature, dust, dirt, light, moisture, fingerprints, and many other external influences can affect the accuracy of color measurement. Consistent handling is also essential, even with different... Mehr lesen
- SaturationAlong with hue and brightness, saturation is one of the three properties that humans perceive in color. The degree of saturation is measured by the distance from the gray point and refers to the intensity or purity of a color. High saturation means a vibrant, pure color, while low saturation... Mehr lesen
- Saybolt Colour NumberThe Saybolt Color Number measures the color of liquids, particularly mineral oils and fuels (e.g., gasoline, kerosene). It is determined using a standardized color system, with higher values indicating a lighter liquid and lower values indicating a darker liquid. Mehr lesen
- SpectrophotometerA spectrophotometer is a device that measures the intensity of light at various wavelengths. It is used to analyze the spectral absorption or reflection of a material and helps in objectively determining the color, transparency, or chemical composition of substances. Using the software of a... Mehr lesen
- SpectrumA spectrum is the division of light into its various wavelengths, which are perceived as colors. Mehr lesen
- StandardA standard is a defined reference used for measurement and calibration. Mehr lesen
- StandardsA standard is a “document” that defines requirements for products, services, or procedures. It therefore provides clarity regarding their characteristics, facilitates the free movement of goods, and supports export activities. Different types of standards: DIN, ISO, ASTM DIN is the... Mehr lesen
t
- ToleranceTolerance refers to the permissible deviation from a specified value or standard. It indicates how much a value can differ from the norm without being considered faulty. Individual tolerances can be set for each color space. Mehr lesen
- TranslucencyTranslucency is the property of a material that allows light to pass through partially, making it appear blurry or diffused but not completely transparent. Examples include frosted glass or thin fabric. Mehr lesen
- TransmissionWhen light strikes a surface, part of it is reflected and some of it is absorbed (see absorption). The remaining wavelengths transmit through the medium until they exit. The degree of transmission is a measure of the proportion of rays that penetrate a sample. Transmission, therefore, is a... Mehr lesen
- TransparencyTransparency is the property of a material that allows light to pass through completely or nearly completely, making objects behind the material clearly visible. Examples include glass or clear water. Mehr lesen
- Tristimulus DeviceA device with built-in color filters that approximate the XYZ color values according to CIE 1931. Mehr lesen
- TurbidityTurbidity refers to the scattering of light by particles in a medium, which affects its clarity. It is typically measured in Nephelometric Turbidity Units (NTU). Mehr lesen
u
- Ulbricht SphereA hollow sphere with an interior wall painted matte white that diffusely reflects light. There is usually an opening for light entry at a right angle and an exit on the opposite side. Mehr lesen
- UV LightUltraviolet light (UV radiation) falls within the wavelength range of less than 380nm, which is not visible to the human eye. This short-wavelength light can accelerate the aging process of products, so standards should not be stored under UV light exposure. It is used in various applications,... Mehr lesen
w
- WavelengthLight rays are electromagnetic waves defined by their frequency/wavelength. The range of the wavelength determines the color of light. The visible spectral range extends from 380nm (violet) to 780nm (red). Mehr lesen
- Whiteness Index, WIRepresents a quality measure in many industrial sectors. To specify and compare the color white, standards are required that are binding in many industries, such as the sugar industry, paper, textile, automotive, printing, and paint industries. A higher WI value indicates a more intense white,... Mehr lesen
x
- XYZ Colour SpaceThe XYZ color space is a mathematical model for describing colors based on human color perception. It uses three primary values (X, Y, Z) to represent each color in the space of visible colors. The Y value represents brightness, while X and Z describe the color components. Mehr lesen
y
- Yellowing Degree, YI (Yellowness Index)The yellowish hue of textile and paper fibers occurs because they preferentially absorb blue light. This wavelength is then missing from the reflected light spectrum, and the object appears yellowish (complementary color). Mehr lesen
- Yellowness Index, YI (see also Yellowing Degree)The Yellowness Index (YI) or yellowing degree measures how much yellow a material has. A higher YI value indicates a stronger yellow tint, while a lower value suggests less yellow or a more neutral white. Mehr lesen
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