ISO 12647-9-2021 pdf download.Graphic technology一Process control for the production of half-tone colour separations, proof and production prints一 Part 9: Metal decoration printing processes using offset lithography.
Quality control of the content of a print job prior to final production checks are recommended since PDF/X conformance does not necessarily ensure a suitable image resolution or other production dependent criteria.
Additional spot colours are allowed, however, this document does not make provisions for tolerances.
4.2.2 Printing forme quality
The resolution of the plate setter should be selected to ensure that at least 150 tone value steps are reproduced.
For a screen employing single half-tone cell modulation, for example, if the intended nominal screen ruling is 80 cm1, the resolution of the plate setter should not be less than 1 000 cm1. For a screen with super-cell technology, it is possible to set the resolution to a smaller value.
4.2.3 Screen frequency (periodic screens)
For four-colour work, the screen frequency (screen ruling) for periodic screens should be within the range from 48 cm1 to 80 cm-1 69 cm-1 (175 lines per inch) is the most common plate frequency.
NOTE 1 The screen frequency is often varied slightly from one process colour to another in order to minimize moire patterns. For example, there can be a difference of up to 6% of the nominal screen frequency between the colours C, M, Y.
NOTE 2 For the black or yellow colour halftone, a screen frequency is sometimes used which is substantially finer than the nominal screen ruling of the remaining colours, for example, 84 cm-1 versus 60 cm-1.
Screen frequencies are often required or given in Ipi (lines per inch). To convert between screens per cm and lines per inch a conversion factor of 2,54 should he used.
The requirement 4.2.3 given in Ipi reads as follows (rounded to commonly used integral numbers): for four-colour work, the screen frequency (screen ruling) for periodic screens should be within the range from 120 Ipi to 200 Ipi.
4.2.4 Dot size (non-periodic screens)
For four-colour work, the screen dot size for non-periodic screens shall be within the range 20 pm to 40 pm and should be within the range 20 tm to 30 pm.
NOTE Outside of the range 20 pm to 40 pm, the general principles specifIed In Iso 12647-1 remain valid but specific values can differ.
4.2.5 Screen angle (periodic screens)
For half-tone dots without a principal axis, the nominal difference between the screen angles for cyan, magenta and black should be 30°, with the screen angle of yellow separated at 15° from another colour. The screen angle of the dominant colour should be 45°.
For halftone dots with a principal axis, the nominal difference between screen angles for cyan, magenta and black should be 60°, with the screen angle of yellow separated by 15° from another colour. The screen angle of the dominant colour should be 45° or 135°.ISO 12647-9 pdf download.