A New Algorithm for Ink Trapping Rate Based on Clapper-Yule Model

摘要

The ink trapping rate is one of the most important factors to control the quality of multi-color printing. Since most of the existing methods are not accurate enough to predict it, a new algorithm based on Clapper-Yule model is proposed in this paper. By keeping the total ink volume in trapping as constant, a new ink trapping model is established for two different color of ink. In this model, it is assumed that the thickness of the first printed ink layer is maintained as the same, and the second printed ink forms a thinner but evenly distributed trapping layer on top of the first one. Based on the above assumption and the Lambert's law, a new algorithm of the ink trapping rate is derived, where the transmillances is the mean value of spectral transmittances within a certain wavelength range calculated through the classic Clapper— Yule model. In order to test the proposed algorithm, two sets of sample data for ink trapping rate from DIC and Pantone color cards are calculated, and the maximum error and the color difference between the predicted value and the corresponding measured value for the spectral reflectivity from Clapper-Yule Model are provided. By comparing with the colorimetric evaluation method, the proposed algorithm is precisely defined and it improves calculation accuracy of ink trapping. The new algorithm is suitable for practical application on multi-printing.