Study On The Color Measurement Methods Of Printed Colors On The Gold And Suverfaper And The Laser Paper

With the fierce competition of the market, the consumers have higher demands to thepackage of the commodities. Owing to the anti-counterfeiting ability and bright effect,gold and silver foil paper and laser paper have got very broad application in packagingindustry. The surface metallic luster of the gold and silver foil paper will lead to a strongspecular reflection and the surface diffraction effect of the laser paper will lead to arainbow effect when the incident light falls on the paper. The superficial color appearanceof a substance will change in relation to the change of viewing angles. It will affect thenaked eyes to identify the color exactly and it will lead to the inaccuracy colormeasurement with the percent of pass declining, which will make the printing costs go up.Therefore, the study on the method of the color measurement of these two papers isimportant to control color quality in the printing industry.The methods used in the experiments were to study the role of the gold tone and silvertone by studying the influence of gold tone and silver tone with different content on thechromatic value of normal color ink with different tone and different saturation. In theexperiments, CIELab chromatic value of including and excluding specular reflectionrespectively in the diffuse light conditions of color measurement could represent thechromatic value of the ink containing gold ink and silver ink. Then the difference of Lvalues between including and excluding specular reflection was defined as lightnessdifference. The ratio of the difference of saturation between including and excludingspecular reflection to the their sum was defined as saturation ratio. Therefore, theCorrelation Properties between lightness difference and saturation ratio was quantified.Different color measurement instruments with different optical geometry conditions wereadopted to measure the chromatic values of the laser paper objectively. And the results ofsubjective observations were used to check the accuracy of the results above in order tochoose a suitable instrument which could describe the characterization of the colorinformation on the laser paper right. The result shows that in practice a linear relation between saturation ratio andlightness difference could be chosen as the foundation of the color evaluation and controlin gold and silver foil paper. The value of dL and CL received in a particular direction whichhas a incident light in a particular direction could be used as rainbow features of light-pillarlaser paper product. So the method of using scanner to scan light-pillar laser paper isfeasible.