ISO 12642-3:2021 pdf download – Graphic technology — Input data for characterization of 4-colour process printing — Part 3: Extended data set including near neutral scale.
1 Scope This document defines a data set of ink value combinations that can be used to characterize four-colour process printing. This data set is not optimized for any printing process or application area but is robust enough for all general applications. While it is primarily aimed at process colour printing with CMYK inks, it can also be used with any combination of three chromatic inks and a dark ink. This document is an alternative to the ISO 12642-2 data set where more neutral scale data are desired. It is not designed as a replacement for ISO 12642-2. 2 Normative references The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 12642-2, Graphic technology — Input data for characterization of 4-colour process printing — Part 2: Expanded data set 3? Terms? and? definitions For the purposes of this document, the following terms and definitions apply. ISO and IEC maintain terminological databases for use in standardization at the following addresses: — ISO Online browsing platform: available at https:// www .iso .org/ obp — IEC Electropedia: available at https:// www .electropedia .org/
4 Technical requirements 4.1 Background The technical requirements and data set definitions that apply to the data set elements of this document shall be in accordance with ISO 12642-2. The key additional requirement that has been identified by the users of the existing target is the need for more black and near-neutral combinations of C, M, Y ink values. In addition, the use of the visual layout of the target has diminished with the increased use of automated scanning spectrophotometers. These two factors have allowed the 29 duplicate ink value sets (patches) to be removed and replaced with 29 new ink value sets (patches) to improve CMY neutral (23 samples) and K-only (6 samples) aspects of printing characterization and profile computation. Many commercial ICC profiling software generates printable target images from the supplied ISO 28178 text files with 8 bit-per channel precision, which is adequate for most purposes. Printable targets are available that have an precision of 16 bits per channel (when integrated by a 3 mm spectrophotometer aperture) thanks to the use of LSB error diffusion when the original 16 bit images were flattened to 8 bits. This is the approach taken in the example target in Annex A. 4.3? Data? set? definition Table 1 lists the ink value sets that have been deleted from the ISO 12642-2 target and shows the IDs of the retained patches with identical values.