spectrum locus (In French lieu spectral) in a chromaticity chart, the outermost limit where the pure spectral colors are located; see also purple line.

spectrophotometer (In French spectrophotomètre) unlike a colorimeter, a colorimetric measuring instrument that measures spectrally; modifications: inline spectrophotometer (measures colors in moving paths or arcs), spectrodensitometer (can also measure color density/density spectrum), goniospectrophotometer (measures color depending on the angle).

spectrodensitometer (In French spectrodensitomètre) class of modern colorimetric measuring instruments which can display not only colorimetric values (without polarizing filter) but also color densities (with polarizing filter) and other parameters derived from these on the basis of spectrally measured data.

spectroanalytic densities (In French densités d’analyse spectrale) density values which allow a subdivision of the process printing inks among the measuring or color separation filters according to their appearance as black colors (SF; these supply the contribution to the “main color densities”) or white colors (WF). Red filter: SF cyan, WF magenta and yellow; green filter: SF M, WF C and Y; blue filter: SF Y, WF C and M. However, since the white colors…

spectral sensitivity (In French sensibilité spectrale) parameter of the photo receivers (sensors) in colorimetric measuring instruments; see M0/M1/M2/M3.

spectral luminous efficiency (In French efficacité lumineuse relative spectrale) see luminous efficiency function.

spectral luminance factor (In French facteur de luminance spectral) measured quantity which a spectrophotometer records directly; relationship between the luminance of a chromatic surface and the luminance of an ideally white surface illuminated under the same illuminant as a function of the wavelength (in practice: at intervals of 5, 10 or 20 nm); basis for the calculation of all other colorimetric values (CIEXYZ, CIELAB etc.).

spectral density (In French densité spectrale de la couleur) optical density of a special color, exclusively measurable with a spectrodensitometer; the measurement is based on the recording of the spectral luminance factor with polarization filter, so that the density spectrum can be calculated in the range from approx. 400 to 700 nm; the curve maximum corresponds to the actual solid density as an indirect measure for the thickness of the printing ink layer, which a…

specimen, sample (In French échantillon) measured object that is compared to a reference.

special color (In French couleur spéciale) unlike a spot color (couleur d’accompagnement) an additional color which, like the process colors CMYK, is reproduced in tone value scales. ICC color offers solutions which not only create multi-channel ICC profiles for CMYK+special color(s) but also reduce multi-channel separations to CMYK (e.g. basICCoolTool spoTTuner) if no printing press with more than four printing units is available or costs for the additional colors are to be saved. Special color…

source profile (In French profil source) see ICC profiles classification.

solvent (In French solvant) 1) in binding agents, the oily component in which the resin components are dissolved; 2) in heatset, gravure and flexo printing inks the substances which are responsible for drying through their evaporation or vaporization (at ambient temperature, with IR radiation or in hot air).

solids content (In French teneur en matières solides) rheological parameter for printing inks; volume or mass concentration (%) of insoluble solid particles in dispersions, e.g. pigments in binding agents (conventionally drying inks) or pigments and resins in solvents (drying and mineral oils).

solid (ink/full-tone) density (In French densité d’aplat) color density of a solid area, i.e. an area fully covered with printing ink, toner or inkjet ink, which is to allow no further influence of the substrate.

software extension, plug in, addition, add-on (In French extension, module logiciel, programme compagnon) third-party module which extends the functional scope of software; in the field of color there are for example the color palettes and color fans from, among others, Pantone and HKS for QuarkXPress or Adobe Photoshop and InDesign, as well as the integrability of DeviceLink profilers through basICColor demon.

soft proof (In French épreuve-écran, épreuve virtuelle) representation of images or printed pages on a monitor for test purposes – unlike hardcopy proof (épreuve papier) – in general, and their contract color-proofed reproduction in particular. A soft proof is contract color-proofed if – the monitor has a greater color space (wide-gamut monitor) than the printing process color space can offer; – the monitor was subjected to successful hardware calibration and then the representation capability of…

SNAP, Specifications for Newsprint Advertising Production American industrial standard for printing newspaper advertisements and supplements with scales for higher color densities: CMYK coldset 0.90/0.90/0.85/1.05, CMYK heatset 0.95/0.95/0.09/1.10.

slur (In French maculage) measure for the tonal value increase caused by unwanted slurring and doubling in offset printing, which also leads to color changes. Slurring and doubling areas in ink control strips are composed of fine parallel lines along and across the cylinder circumference and have a definite integral density, whose percentage increase corresponds to the slur factor.

slope (In French pente) lead factor that can be set in filter densitometers with which the measured density can be multiplied to compensate for deviations between several devices or devices from different manufacturers. To avoid this dubious trick, it is recommended that devices from one and the same manufacturer should be used. Modern spectrodensitometers have such low manufacturing tolerances (Techkon e.g. 0.01 density units or ΔE*ab 0.3) that this function is no longer offered.

skin color, human complexion (In French couleur chair) color shades that make particularly high demands on visual correspondence with color measured data and color management results and during quality control in production printing.