ISO 12647-3:2013 pdf free
ISO 12647-3:2013 pdf free.Graphic technology一Process control for the production of half-tone colour separations, proofs and production prints
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°. The dominant colour is defined as the one that contains most of the image information compared to the others. For typical newspaper applications the dominant colour will be black. Refer to Figure 1 for an example of a screen angle combination for a screen with a principal axis and with black as the dominant colour.
For half-tone dots with a principal axis Celliptical half-tone dot shape), the nominal difference between screen angles for cyan, magenta and black should be 60°, with the screen angle of yellow at 0° and 15° off from the next screen angle. The screen angle of the dominant colour should be 45° or 135°.
Unless otherwise specified, the tone value sum should not exceed 220 % and shall not exceed 240 %. Where the maximum tone value sum approaches this limit, the tone value of black should be at least 90 %.
NOTE Any colour that is reproduced using all three chromatic process inks can be thought of as having a neutral component. This is defined by the lowest tone value and its grey balance equivalents of the other two inks. It is possible to replace all or some of the neutral component by black ink. Under colour removal (UCR) limits the tone value sum by replacing chromatic colour ink with black ink in the neutral shadows. Grey component replacement (GCR) replaces chromatic colour ink with black ink in the entire colour space. GCR is recommended for newspaper colour separations because it reduces colour variations caused by poor ink trapping, back transfer,set-off during the print run, and eases registration.ISO 12647-3 pdf free.
