Clapper-yule Reflectance Model Of Halftone Image Printed On The Fluorescent Substrate

In the process of printing, representation of color accurately is especially important. Therefore, it is necessary to control and detect the color information strictly in the production of printing. In order to improve the efficiency of production, we usually adopt color management software and color detective system for effective control and detection. Establishing color prediction model is the core part of the color management system. This shows that color prediction model is the theoretical basis of automated printing. As is known to all, actually there are many factors affecting the formation of color printing process, and quantify the color of these factors to establish and improve the prediction model is a very necessary and valuable work. In the general case, the printing paper contains fluorescent material. So, this paper focuses on the influence of the fluorescent substrate on the color prediction model and establishes the corresponding theoretical model.This paper is based on the assumption of the refractive index of the ink image being same as the refractive index of the paper and the distance classification Clapper-Yule model. The fluorescent substrate absorbs the invisible ultraviolet light and emits the visible light, which can affect the total reflection of the print. Four parameters(the upward reflectance of the paper substrate, the downward reflectance of the paper substrate, the image transmittance of the recto and the image transmittance of the verso) are put forward. In the view of single lighting, we extend the distance classification Clapper-Yule model of recto-verso printing to a new Clapper-Yule spectral reflectance model of recto-verso monochrome halftone image printed on the fluorescent substrate. Then,considering optical dot gain factor, we improve the new model. Using the Demichel equation, a front reflectance model of Clapper-Yule for recto-verso multicolor halftone image printed on the fluorescent substrate is established. Finally, the new model is demonstrated to be reasonable through data simulation. The reflectance of considering the fluorescent effect is higher than that of not considering fluorescent effect, and the color difference of considering the fluorescent effect is smaller. This paper pointed out that when using fluorescent paper to print, we should modify spectral reflectance values. The fluorescence effect of fluorescence-based paper should be considered by introducing the modifying fuction of fluorescence-based papar when designing the quality control system of the color management for printers.