双面半色调图像的光谱反射率色彩精确预测模型

为了准确地预测双面半色调图像的光谱反射率,并考虑光在纸张内的散射和油墨在纸基上的扩展渗透,建立了一个统一的双面半色调图像光谱反射率精确色彩预测模型.在油墨是非散射介质,纸张为强散射体以及油墨和纸张具有相同的折射率的条件下,引入Williams-Clapper模型中光在油墨中斜程传播的思想,考虑进入纸基层的光线横向传播和油墨扩展导致的网点扩大效应以及光在纸基和印刷品-空气界面间的多重内反射,利用多重内反射的网状结构分析法和最小二乘曲线拟合方法,确定了各种不同叠印条件下的理论网点面积率和有效网点面积率的函数关系,得出彩色双面图像的光谱反射色彩精确预测模型.新模型的预测值和测量值达到了较好的匹配,同时这也为彩色双面图像的呈色规律分析和印刷品质量检测系统的研制与开发提供了理论依据.

Color Precise Prediction Model of Spectral Reflectance for Recto-verso Halftone Images

 In order to predict the spectral reflectance of recto-verso halftone images,the scattering of light within paper and the ink penetration in the substrate are considered and the color spectral reflectance precise prediction model for recto-verso halftone images is proposed.Based on the assumption that ink is a non-scattering medium,paper is a strong scattering substrate,both of which have the same refractive index,the Williams-Clapper model is proposed.The ink-spreading model includes nominal-to-effective dot area coverage functions for each of the different ink overprint conditions by the least square curve fitting method and the network structure of multiple reflection.It turned out that the modeled and the measured colors agree very well,confirming the validity of the used model.The new model provides a theoretical foundation for color prediction analysis of recto-verso halftone images and the development of prints quality detection system.