Glossary of terms
Technical terms simply explained
Japan Color see DIC
JFIF see JPEG
JND, just noticeable difference seuil de différenciation visuelle brightness and/or chromaticness-related difference which is determined in so-called color threshold experiments (MacAdam ellipses); on the basis of thresholds determined in this way between “not noticeable” and “just noticeable difference”, perceptually equidistant color systems are constructed, e.g. CIELAB.
JOSA, Journal of the Optical Society of America internationally leading technical journal for colorimetry.
JPEG, Joint Photographic Expert Group CCITT/ISO group of experts that developed the compressible pixel graphic format JFIF (JPEG File Interchange Format, .jpg) and a related video procedure (Motion JPEG, MJPEG, MP4). The greater the compression, the greater the information loss, which becomes apparent through annoying artefacts in the image; even when the JPEG file is available in RGB, it is internally coded according to the YCC color model in the color channels Y (lightness), Cb (blue-yellow chrominance) and Cr (red-green chrominance) and is only decoded into RGB when it is retrieved or processed The further development JPEG 2000 allows the choice between extremely high and lossless compression with up to 256 definable channels. ICC profiles and working color spaces can be embedded in JFIF and JPEG 2000.
just covering ink quantity seuil de couverture ink quantity (in g/m²) required to create a solid film of printing ink on the substrate; indirect measure for substrate smoothness, for the lower the just covering ink quantity, the greater the smoothness.