Glossary of terms
Technical terms simply explained
radiation rayonnement electromagnetic waves characterized by wavelength or their reciprocal frequency, intensity, density, spectral composition and thus also their interactions with the environment. Photometric factors are special cases of radiation field factors:
Q = luminous energy quantité de lumière [lumen × second] = radiant energy énergie rayonnante [joule]
Φ = luminous flux flux lumineux [lumen] = radiant power/flux puissance rayonnante, flux énergétique [watt]
I = luminous intensity intensité lumineuse [candela] = radiant intensity intensité énergétique/de rayonnement [watt per steradian]
E = illuminance, illumination éclairement [lux] = irradiance éclairement énergétique [watt per square meter]
L = luminance, lightness luminance [candela per square meter] = radiance, radiant density radiance, luminance énergétique [watt per steradian × square meter]
H = light exposure, illumination quantity exposition lumineuse, lumination [lux × second] = radiant exposure, irradiation exposition énergétique [joules per square meter]
radiation-curing séchage par rayonnement principle of film formation in printing inks whose binding agents link up through the influence of UV or electron beams (ESH).
RAL Design System, RAL-DS système RAL color sample system introduced by Ludwig Gall in 1993 for varnishes and paints in product and room design, e.g. car body paints, painting materials or textile colors. Gall extended the RAL 840-HR from 194 to 1688 color shades and placed it on a CIELAB and/or CIELCH basis (written HLC, maximum 80 grades), whereby all neighboring color samples have a color difference of ΔE*ab = 10 with respect to each other.
raster image, bitmap image en mode point digitally implemented continuous tone image in pixel structure.
RAW format d’image RAW generic term for RGB raw data formats of digital cameras.
recipe dyeing coloration dyeing of objects according to recipe (e.g. textiles, paper, glass, plastics, liquids).
recycled grades papiers recyclés paper/cardboard with a high proportion of recyclable fibers; modern recycled products, for example this brochure printed on Arjowiggins recycled paper, have overcome previous disadvantages like a yellow-brownish to gray color cast in paper white, or whiteness fluctuations, and today offer a basis for stable color rendering for the entire production run.
redness dominante rouge in the sense of opponent color theory, the hues of the red area vis-à-vis the green tones; in CIELAB a*>0; see also blueness, yellowness, greenness.
reference stimulus stimulus de référence color stimulus that serves as a reference for a color measurement in a sample; for color measuring instruments themselves, the reference stimulus is the absolute white standard.
reflection réflexion controversially defined phenomenon describing the casting back of light waves and simultaneous weakening of the luminous flux. 1. Illogical differentiation in designation between specular/regular reflection (réflexion spéculaire/pure) as “reflection” and diffuse reflection (réflexion diffuse) as “remission”, which is why the bvdm only mentions reflection in its German Media Standard Print. 2. What speaks out against this, however, is the worldwide common designation “spectral remission factor”, which results from the measurement of the diffusely reflected part of light (“remission”) in color measurement, which justified the following distinction: Reflection means the casting back of the waves with reference to the surface structure, which leas to a specular and a diffuse part, which can be shown in a so-called indicator; 2a) The gloss or mattness/roughness of the surface is evaluated by the gloss angle; the lower the reflectance factor (réflectance, facteur de réflexion), the matter/rougher the surface. 2b) The densitometric variables (measured using a polarizing filter, which eliminates residual gloss from wet color surfaces) are determined using the gloss-free angle. 2c) When the density spectrum is recorded, the spectral absorptance is measured and the highest point of the absorption curve is determined as the standard for the ink film thickness, so that the remaining scanned spectrum is irrelevant, so that one can talk of neither reflection nor remission, but rather of a maximum absorption at the determined wavelength.
reflective original/copy document à réflexion, document opaque repro copy that can be processed in on-light mode; opposite: transparent copy (transparency);
regime of measurement géométrie de mesure sequence of a measuring operation within a system purpose; distinctions are made between offline measurement (obtaining and showing measured values), online measurement (measured values are also used semi-automatically, “open loop”, régulation à boucle ouverte), nearline measurement (like online measurement, but in absolute spatial proximity to the other service systems, e.g. at the printing press control panel), inline measurement (obtaining machine-integrated measured values and using them fully automatically; “closed loop”, régulation à boucle fermée
relative print[ing] contrast quality parameter in the printed image which can be determined by means of a densitometer; calculated from the difference between solid density and screen density, divided by the solid density.
relative spectral radiation distribution curve répartition spectrale relative d’énergie standardized spectral intensity distribution S(λ) of a light source, measurable for example with a Just GL Optics mini-spectrometer.
remission rémission controversially defined phenomenon describing the casting back of light waves and simultaneous weakening of the luminous flux (see reflection). In accordance with the understanding of remission in colorimetry (see spectral luminance factor) the following distinction can be made: Remission is the emission of radiation by all secondary radiators. Only the spectral elements of the irradiated light that are not absorbed by a surface are remitted by this surface, e.g. red surfaces remit the red radiation elements and absorb the green and blue elements.
remission spectrumspectre de rémission see spectral luminance factor
remitting colors couleurs réfléchies opaque colored substances or surfaces whose color stimulus is determined by the absorption or remission properties of their colorant (pigments, dyes) and the illuminant; the color synthesis model for A. Is C+M+Y, supplemented in printing by black K.
remote inking adjustment/control commande à distance de l’encrage present in all printing presses with a central control console on the front edge of which the color control desk is located, with the ink key pushbuttons +/–.
rendering intent intention/mode de rendu regulation for gamut mapping to be selected within the framework of color management; four regulations are distinguished in the ICC profile format specification: absolute match (absolutely colorimetric, exact 1:1 color communication), reference match (relatively colorimetric, exact color communication with respect to white point of the output medium), saturation match (maintains saturation) and perceptual match (perception-related, photographic, taking account of environmental influences like the viewing environment to be assumed).
renotation renotation further development of a color system through recalculation or correction.
repeatability répétabilité statistically verifiable repetitive accuracy.
resolution résolution number of pixels per unit of length (pixels per inch, ppi) of input devices (camera, scanner), of the dots (dots per inch, dpi) of output devices (desktop printers, digital printing systems, plate imaging) or of the screen elements (“screen ruling” in lines per centimeter, L/cm, 1/cm, lines per inch, lpi) of print subjects. Resolution, screen ruling and grayscale are related by the following formula: (resolution [ppi, dpi] / screen ruling [lpi])² +1 = grayscale [number]; for this reason, a pixel diagram in the required output size should have a resolution of at least 300 ppi × 300 ppi. Special features of digital printing systems: Resolution is given in dpi × dpi, because horizontal and vertical values can differ; inkjet production printing systems can as a rule realize 600 dpi × 600 dpi physically, and 1200 dpi ×1200 dpi through interpolation.
retina rétine location of the color stimulus input (color perception) in the eye. The retinal receptors are the cones (uvulas, cônes) for trichromatic daytime vision and the rods (bâtonnets) for monochromatic scotopic vision. Most cones are concentrated in the macula lutea (tache jaune), and in the middle is the fovea (fovéa), the point of sharpest vision. The receptorless entrance of the optic nerve is called the blind spot (point aveugle).
RGB RVB color space model for additive color mixture (see there).
rheology rhéologie theory of flow properties (consistency, stringing, thixotropy, viscosity, stickiness, tack); important for the wetting and adhesion of the printing ink on the substrate and on each other.
Richter’s law loi fondamentale de Richter with respect to the retinal receptor types, Manfred Richter defined as follows in 1948: “The brightness-adapted trichromatic eye evaluates incident radiation according to three independent spectral response functions in a linear and constant manner, whereby the individual responses add up to one indivisible overall response.”
RIMM-RGB, Reference Input Medium Metric RGB RGB working color space (PIMA 7666) specially developed for scene-related raw color image data, i.e. digital camera raw data (RAW) with defined conversion into CIELAB.
RIP, raster-image processor processeur de rastérisation d’image, générateur d’image tramée workflow component in which rasterization is carried out for the illustration of printing plates or digital print output; in the PostScript workflow (obsolete) possible location for the implementation of the last color transformation within the framework of In-RIP separation.
rods bâtonnets (de la rétine) retinal receptors responsible for scotopic vision.
rub/scratch-off ink encre grattable opaque latex printing ink, in some cases with metallic-effect pigments, which is printed on a previously applied release varnish to guarantee a reading protector or its removal through scratching off; can be implemented in flexo printing, screen printing, but also with inline varnishing units; rub/scratch-off ink can be overprinted.
runability roulabilité the total effect of all printing ink properties with respect to drying behavior, consistency, wetting ability, emulsifying qualities and propensity to cause printing problems.