基于傅里叶变换和梯度法构建纸张匀度评价模型

A Math Model for Paper Formation Evaluation Based on Fourier Transform and Gradient Method

采用傅里叶变换滤波和梯度分析法构建了纸张匀度分析的数学模型,在梯度分析中,为了提高运算速率,采用Roberts算子替代微分。并将该方法与国际上通用的标准匀度指数模型及人眼视觉评价方法进行对比分析。结果表明,该方法思路简单、运算速度快,有效地去除了噪音,既反映了纸张局部定量的微弱变化,又反映了整体定量的变化情况,与标准匀度指数和人眼视觉评价结果有很好的相关性。

Paper formation is one of the most important factors influencing paper quality,as almost all physical properties,optical properties and printing performance are influenced by paper formation. The mathematical model of paper formation was established by using gradient method to deal with the image filtered in the Fourier domain. In order to improve computing speed,in gradient analysis the method by using Roberts operator to replace differential was used. Compared the results of this model with the indexes of standard formation and visual evaluations＇,this method was simple and high speed of calculation,and it could remove noise effectively. It not only reflected the slightly changes of paper local basis weight,but also the changes of whole basis weight. The results of this model agreed with human visual evaluations＇ and the indexes of standard formation very well.