Research on Bivariate Interpolation Mathematical Model of Ink Key Presetting Based on CIP3

The key problem of the ink key presetting is to build the mathematical model which can reflect the relationship between plate information and the ink key opening accurately. The present mathematical model built was used the least square method and only considered the halftone dot coverage and the ink opening. The model was univariate function model and can not explain the same halftone dot coverage with the different ink opening. For this, based on the CIP3 ink presetting technique, the data stream of the prepress was analyzed and compared with the experimental data, then 1-bit tiff images after RIP was selected as the data resources for ink zone control. Based on the system identification theory, the three-dimensional mathematical model was built by the bivariate interpolation method, which can reflect the relationship between halftone dot coverage (the distribution of the ink zone was considered) and the ink key opening. The model was validated by the experiment. The calculation accuracy of this model and the model in literature built by the least square method was compared by the squared error theory. The result showed that the former (the model built by the bivariate interpolation method) has higher calculation accuracy than the later. It provided the foundation for combination of color management and ink preset in prepress, and provided basis for ink key opening preset rapidly and accurately.