Study On The Correlation Between Paper Printability And Printing Quality

At present, the maximum concentration of consumers for the pulping andpapermaking industry is the printing and packaging industry. The cost of paperaccounts for60%~70%of the total cost for printing. Paper printability is thefirst factor to determine the printing process and quality. Therefore, revealingand predicting the mechanism and the effect of paper printability is a particularlyprominent and important task for both the papermaking and the printing andpackaging field. However, due to the complex multiple correlations anduncertain influence factors of "paper-printing", the technical problem has notbeen broken through.This subject focuses on the printability of different paper and analyzes thecorrelation between each paper performance and responsive printing effects.Then the multivariate nonlinear analytic expression is established. From the viewof synthesizing index, the mathematical model for comprehensive evaluation ofpaper printability is studied and provides quantitative and scientific judgmentreference for paper in the same or different level. From the connective view ofpaper and printing, the concepts of paper comprehensive index and printingquality comprehensive index are put forward respectively. The predictionmechanism and model of paper printability is discussed. Based on the spectralimaging technology, four kinds of schemes are used to realize the printing matchand evaluation between the reference paper and the test paper. And the totalreflection and transmission model of a high quality paper is characterizedspectrally as a lambert body. Then a special paper printability file and itsprogramming module are created. The roles and laws between paper printabilityand the target tone and color transmission are revealed. The three keytechnologies which are respectively color gamut boundary, color gamut mappingand rendering intentions are studied and the new algorithms for above are putforward. Then the correlation law of automatic selection and matching accordingto the different printing feature of paper printability is studied. This paper aims to provide a quantitative science criterion suitable for printing conditions for paperand form system theory guide for paper application and printing practice control.And it will promote high quality production and specific application fortechnology of papermaking and printing.Properties of paper printability are numerous and complex and therefore arestudies of correlation. Firstly the influences of the paper printability (includingsmoothness, ink absorption, gloss, whiteness, opacity, evenness index, surfacestrength) on the printing effects (including the C, M, Y, K solid printing density,designated printing image gamut volume and50%dot gain) are analyzed by greycorrelation analysis and sorted according to the correlation degree. And then thetop three influential factors are selected as the independent variables of themodel based on the multivariate nonlinear regression. Finally the approximatemodel between paper main performances and its responsive print effects isestablished. Results show that the approach can quantify the multiple complexnonlinear relationship between paper and printing effectively and clearly and thebest combination results of performances are got.We can make a correct evaluation on paper only when many paperperformances are synthesized. Based on the classification quality standard of artpaper which is summarized by myself, six main paper properties, includingsmoothness, gloss, whiteness, ink absorption, surface strength and opacity, areselected. Then by using the Radial Basis Function(RBF) neural network, with360groups of custom training samples as input of the network, with the papercomprehensive assessment level as the output of the network, the RBF neuralnetwork model for comprehensive evaluation of art paper quality is built. And250groups of the known quality grade art paper are used to test thecomprehensive model. Furthermore we use the BP neural network model forcomparison. Results show that the evaluation results for art paper quality basedon RBF neural network are more accurate and trustworthy than that of BP neuralnetwork. The evaluation model reduces the influence of subjective factors,simplifies the calculation steps and provides a new train of thought for thecomprehensive evaluation of paper quality. In order to sort the quality of paperfurther, the model of paper quality based on Artificial Fish Swarm-ProjectionPursuit algorithm is put forward. And15examples which each includes six indexes as the main parameters are selected as the training samples and9samples as testing samples. Research has shown that there is no subjectiveweights in the evaluation process and the result is a specific value. Therefore, theresearch program has the high comparability and more suitable for theassessment of the same grade paper.The combination of paper and printing for prediction of paper printability ismeaningful. The paper performances and the printing quality indexes arerespectively analyzed using Principal Component Analysis(PCA). The variancecontribution rates of principal components are used as the weights. Thecomprehensive evaluation of paper or printing can be got by the sum of linearweighting and it synthesizes paper performance and printing effect. Then theprinting comprehensive quality index are used as the dependent variables and thecomprehensive properties of paper as independent variables. Then therelationships between printing comprehensive quality and comprehensiveproperties of paper are discussed and the paper printability is forecast finally.The method provides a specific formula which is very convenient, quick andobjective for application once the parameters are determined.Paper properties based on spectral imaging technology are studied and fourkinds of schemes including Lambert Beer law, the Neugebauer equation,Kubelka Munk model equation and Principal Component Analysis are putforward to match and evaluate the relationship between the test paper and thereference paper. Results show that the project by PCA is the most complicated,but it is better to evaluate. The Neugebauer equation comes second. The methodsby Lambert Beer law and Kubelka Munk model are worse but a small amount ofcalculation. Furthermore paper is regarded as a six-interfaces body and brokendown into three sections. Then the new spectral model of paper reflectivity andtransmissivity is deduced by the combination of three sections above. Resultsshow that the characterization of the total reflection and the transmission of highquality and glossy paper (as a lambert body) is more simple and direct in avariety of measuring geometric conditions. In addition, the air-paper interfacehas been split which dissociates the measurement geometric-dependentparameters and the measurement geometric-independent parameters effectively.After inspection, the model can characterize and get the spectral characteristics of paper well.We put forward and set up the custom paper property file which makespaper and ink used adapt and match well. The detailed steps are built anddetermined for paper property file, including the basic linearization of printingequipments; the judgment of the color number suitable for ink most; therecommendation of the maximum ink thickness and ink volume. And the specificestablishment steps are programmed by relevant software so as to be invoked inthe color management system. Finally the paper property file is plugged into oneof the three modules in Window Color System. The research can be applied inprinting system well and serve for the actual printing production.The three color reproduction technologies which include color gamutboundary, gamut mapping and rendering intentions are studied respectively withproposing new algorithms. For the color gamut boundary algorithm, the newcombination scheme is proposed based on the Segment Maxima GamutBoundary Description(SMGBD) and convex hull algorithm used commonly.Analysis results show that the precision of convex hull algorithm is higher thanthat of SMGBD and the combination algorithm but the calculation process andthe actual use of SMGBD is better than the other two. The combinationalgorithm is in between. For the color gamut mapping, the color space is carriedout by the Genetic Algorithm. The results show that it is more advantageous thantraditional cutting algorithm. For rendering intentions, the characteristics andapplication range of four intentions are summarized by experiments. Finally, therelationships among paper performances, color gamut boundary algorithm,gamut mapping methods and rendering intentions are analyzed. Then theschemes and flows of automatic selection of color technology according to paperperformance are studied and the automatic selection functions are realized byVC++software.