具有打底油墨的半色调印刷品的Clapper-Yule模型

通过经典的Clapper-Yule模型的应用,对已有的点对点的半色调印刷品进行扩展,在忽略油墨渗透的条件下,建立起能具有打底油墨的半色调印刷品的呈色规律的理论模型.在假定油墨是非散射介质以及油墨的折射率与纸张的折射率近似相等的近似下,利用光在油墨与纸张中散射迁移路径长短不同的分程理论,建立了具有打底油墨的半色调图像的分程Clapper-Yule光谱反射率模型.     

油墨渗透下荧光半色调印刷品的预测模型

旨在普通油墨渗透条件下,建立能预测不同浓度的均匀荧光油墨半色调印刷品的呈色规律的理论模型;在假定油墨是非散射介质以及油墨的折射率与纸张的折射率近似相等的近似下,利用光在油墨与纸张中散射迁移路径长短不同的分程理论,建立了油墨渗透下荧光油墨半色调图像的分程Clapper-Yule光谱反射率模型.     

商标印刷色彩预测 Clapper-Yule 模型

把油墨与纸张等价为吸收薄膜,考虑光在纸基油墨间多重内反射和横向传播,运用吸收膜理论,建立了半色调商标印刷品的Clapper-Yule 色彩预测膜层模型。通过数值计算并与实验值比较,证明了新模型的预测精度明显高于之前的Murray-Davies 模型,而且改进了经典Clapper-Yule 模型预测偏暗的问题。     

基于荧光基Clapper-Yule光谱模型的墨层厚度变化预测

由于荧光纸基会吸收紫外线,激发可见蓝光或可见紫色荧光,而影响墨层厚度,为此基于荧光纸基的Clapper-Yule光谱反射色彩预测模型,考虑了荧光纸张的光学特性、光在荧光纸内部横向传播等特性,采用最小二乘参数估计方法,通过印刷品光谱反射率反映荧光纸基的墨层厚度变化量。该模型可为彩色印刷品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一定的理论依据。     

彩色双面半色调印刷品光谱反射率与透射率预测模型

为了准确地预测多色双面半色调印刷品的呈色特性,建立一个统一的半色调印刷品光谱反射透射预测模型,对纸张的固有反射率和透射率以及油墨的光谱透射率进行精确的测量和计算.为提高半色调印刷品反射透射预测模型的精度和双面印刷品在线质量检测仪器的开发,提供理论依据.     

存在油墨渗透印刷品色彩预测Kubelka-Munk理论模型

油墨与纸张均是均匀介质,将印刷品分为油墨层、油墨渗透层和纸张层,并分别建立模型,在漫反射光的照射下,利用Kubelka-Munk理论和多重内反射的Sanderson修正,以及以点扩散函数为基础的网点扩大的修正,来建立新的半色调印刷品色彩预测模型.在此基础上,将模型推广到双面半色调印刷的情形.新模型也可为印刷品的呈色规律分析与印刷品在线检测提供理论依据.     

单色半色调墨点非规整Clapper-Yule分程模型

目的 研究非规整的墨点（非二值理想墨点）形态对光谱反射率的影响, 为预测模型的理论研究提供一个新的思路。方法 通过讨论墨点的非规整形态对网点大小、 厚度及油墨透射率的影响, 采用二维高斯函数模拟墨点表面的形态, 由此建立一个Clapper-Yule扩展模型。结果 模型的数值模拟结果表明墨点的非规整性导致了网点的物理扩大, 增加了油墨对光的吸收, 降低了最终的光谱反射率。结论 采用Clapper-Yule分程模型对颜色进行预测时需考虑墨点的非规整所带来的物理网点扩大, 该模型适用于单色半色调的颜色预测与控制。     

荧光油墨印刷品的预测模型

荧光油墨半色调印刷品的显色预测规律是彩色成像领域内十分关键的课题.详细介绍了荧光油墨印刷品的经典Clapper-yule预测模型以及其改善的模型分程Clapper-yule预测模型,并且介绍了基于点扩散的Clapper-yule预测模型.同时分析了各个模型的特点,最后进行前景展望.     

塑料包装印刷品色彩再现规律研究

通过分析影响彩色塑料包装印刷品色彩再现的影响因素并考虑了油墨与塑料底基折射率的差异,把入射光透射到底基后的反射光光分为Fresnel反射光与漫反射光;结合油墨的吸光特性、塑料的光学性质,利用Williams-Clapper理论,用辐射传递法对各种影响因素进行分析,得出塑料包装印刷品反射率的数学模型.     

半色调荧光油墨印刷品的Murray-Davies反射模型

荧光油墨防伪印刷的色彩预测是防伪印刷质量控制领域十分关心的课题.通过分析光在荧光油墨层中的传播时的吸收、散射和荧光辐射规律,分别研究油墨层中存在的3类传播光束在传播过程中的消长规律,利用反映光半色调墨层中传播规律的Murray-Davies模型,建立了半色调荧光油墨印刷品的Murray-Davies反射新模型.     

Reflectance and transmittance model for recto-verso halftone prints

We propose a spectral prediction model for predicting the reflectance and transmittance of recto-verso halftone prints. A recto-verso halftone print is modeled as a diffusing substrate surrounded by two inked interfaces in contact with air (or with another medium). The interaction of light with the print comprises three components: (a) the attenuation of the incident light penetrating the print across the inked interface, (b) the internal reflectance and internal transmittance that accounts for the substrate's intrinsic reflectance and transmittance and for the multiple Fresnel internal reflections at the inked interfaces, and (c) the attenuation of light exiting the print across the inked interfaces. Both the classical Williams-Clapper and Clapper-Yule spectral prediction models are special cases of the proposed recto-verso reflectance and transmittance model. We also extend the Kubelka-Munk model to predict the reflectance and transmittance of recto-verso halftone prints. The extended Kubelka-Munk model is compatible with the proposed recto-verso reflectance and transmittance model. In the case of a homogeneous substrate, the recto-verso model's internal reflectance and transmittance can be expressed as a function Kubelka-Munk's scattering and absorption parameters, or the Kubelka-Munk's scattering and absorption parameters can be inferred from the recto-verso model's internal reflectance and transmittance, deduced from spectral measurements. The proposed model offers new perspectives both for spectral transmission and reflection predictions and for characterizing the properties of printed diffuse substrates.     

Spectral model of a fluorescent ink halftone

A model is presented of a fluorescent ink halftone. Unlike a nonfluorescent ink, which only absorbs, a fluorescent ink absorbs higher-energy photons and emits lower-energy photons. The amount of fluorescent light produced depends on the percent absorption of the incident light. For fluorescent ink printed on paper, both photon scattering within the paper substrate and multiple internal reflections between the ink layer and the paper substrate significantly increase the percent absorption, so a realistic model must include these effects. The model presented here utilizes the generalized Clapper-Yule theory, which accounts for photon diffusion that is due to both scatter and internal reflection. It is shown that while multiple internal reflections alone only marginally increase the percent absorption, when there are both scattering and internal reflection, the percent absorption is increased significantly. The current study is a theoretical model and does not present experimental results.     

Yule-Nielsen based recto-verso color halftone transmittance prediction model

The transmittance spectrum of halftone prints on paper is predicted thanks to a model inspired by the Yule-Nielsen modified spectral Neugebauer model used for reflectance predictions. This model is well adapted for strongly scattering printing supports and applicable to recto-verso prints. Model parameters are obtained by a few transmittance measurements of calibration patches printed on one side of the paper. The model was verified with recto-verso specimens printed by inkjet with classical and custom inks, at different halftone frequencies and on various types of paper. Predictions are as accurate as those obtained with a previously developed reflectance and transmittance prediction model relying on the multiple reflections of light between the paper and the print-air interfaces. Optimal n values are smaller in transmission mode compared with the reflection model. This indicates a smaller amount of lateral light propagation in the transmission mode.     

Extending the Clapper-Yule model to rough printing supports

The Clapper-Yule model is the only classical spectral reflection model for halftone prints that takes explicitly into account both the multiple internal reflections between the print-air interface and the paper substrate and the lateral propagation of light within the paper bulk. However, the Clapper-Yule model assumes a planar interface and does not take into account the roughness of the print surface. In order to extend the Clapper-Yule model to rough printing supports (e.g., matte coated papers or calendered papers), we model the print surface as a set of randomly oriented microfacets. The influence of the shadowing effect is evaluated and incorporated into the model. By integrating over all incident angles and facet orientations, we are able to express the internal reflectance of the rough interface as a function of the rms facet slope. By considering also the rough interface transmittances both for the incident light and for the emerging light, we obtain a generalization of the Clapper-Yule model for rough interfaces. The comparison between the classical Clapper-Yule model and the model extended to rough surfaces shows that the influence of the surface roughness on the predicted reflectance factor is small. For high-quality papers such as coated and calendered papers, as well as for low-quality papers such as newsprint or copy papers, the influence of surface roughness is negligible, and the classical Clapper-Yule model can be used to predict the halftone-print reflectance factors. The influence of roughness becomes significant only for very rough and thick nondiffusing coatings.