基于非负矩阵分解的印刷品原稿原色油墨光谱预测方法

The Spectral Prediction Method of Primary Ink for Prints Manuscript Based on Non-Negative Matrix Factorization

实现半色调印刷品原稿的光谱复制技术其前提要确定原稿所用油墨数目及油墨成份,但目前应用于印刷品原稿原色油墨光谱预测的算法还有待研究,且已有的基色色料光谱预测方法存在诸多弊端。针对这一问题在非负矩阵分解算法基础上结合印刷品原稿光学特性,创新的提出了一种基于约束条件非负矩阵分解的油墨光谱预测算法ISPNMF,和对黑色油墨光谱预测结果优化的算法。ISPNMF算法克服了基本非负矩阵分解有多重最优解和局部极小值的缺陷,实现了预测算法唯一的全局最优解。黑色油墨预测光谱优化的算法克服了彩色油墨对光线混合吸收给黑色油墨预测带来的干扰,能优化得到逼近于实际黑色油墨光谱的预测值。使用Konica Minolta C1085和HP indigo5600两台四色数码印刷机及其自身配备的墨粉和墨膏来摸拟不同品牌的油墨,在230 g白卡纸上打印IT8. 7/3色标,并使用X-rite i1 Pro2获取两样张的光谱反射率作为实验数据样本,来探究并验证算法的准确性和实用性。实验结果表明,在印刷品原稿线性经验空间中能准确预测原稿所用原色油墨数目和油墨光谱,且彩色油墨预测光谱与实际使用的油墨光谱相比其拟合度均高达99. 9%,光谱角距离均小于0. 045,黑色油墨的预测光谱经优化后与实际油墨光谱拟合度也高达99. 9%。这说明该算法不仅能实现对印刷品原稿原色油墨的准确预测,而且可以精确匹配实际使用的原色油墨,对实现印刷品原稿的光谱复制技术有重要意义。

To achieve the spectral reproduction technology of halftone prints manuscript,the number of primary ink and the ink composition used in the manuscript should be specified before hand.However,there are still many problems to be solved in the primary ink spectral prediction for prints manuscript,and existing m ethods of spectral prediction have many disadvantages.To solve this problem,the algorithm of primary ink spectral prediction based on constrained non negati ve matrix factorization ISPNMF,and the optimizing algorithm for black ink spec tral prediction have been put forward innovatively.The short comings of multiple optimal solutions and local minima of the basic non-negative matrix factoriz ation were overcome,and the unique global optimal solution was realized by the algorithm of ISPNMF.The interference of prediction black inkcaused by the colored inks mixed absorption was eliminated by the optimizing algorithm for black ink spectral prediction,and the optimized result was close to the actual black ink spectrum.The accuracy of the algorithm was verified by using the samples of simulating different brands ink.In the experiments,Konica Minolta C1085 an d HP indigo 5600,two kinds of four-color digital printing machine,with its toner and ink paste mimicking different brands of ink,were used.And the IT8.7/3 color card was printed in 230 g white cardboard,then X-rite I1 Pro2 was used to obtain the spectral reflectance data of two proofs as the experimental samples,to explore and verify the accuracy and practicability of the algorithm s.The experimental results showed that,the number and spectrum of primary inks u sed in the printed manuscript can be accurately predicted in the linear empirica l space.The GFC of prediction results of color inks were all up to 99.9%,and the SAD were all less than 0.045.The GFC of prediction results of black inks,w hich were optimized,were also up to 99.9%.The algorithms can not only predi ct theprimary ink of prints manuscript accurately,but also can match the actua lprimary ink precisely.It is of great significance to the realization of the spectral replication of prints manuscript.