TAPPI T 519 om-17提供了白纸和近白纸的漫反射不透明度（纸张背衬）测量， 以前称为“打印不透明度”该方法可用于彩色纸张，条件是其反射率（纸张背衬）为 大于20%，且其漫反射不透明度（纸张背衬）大于45%（1）。该方法不适用于玻璃纸等高度透明的纸张。该方法采用d/0几何体、光源C和纸背衬，而TAPPI T 425“不透明度 “纸张”采用15/d几何结构，光源A，89%反射背衬和纸张背衬。该方法类似于ISO 2471。

TAPPI T 519 om-17 provides a measure of diffuse opacity (paper backing) of white and near-white papers, previously known as "printing opacity."The method may be employed for colored papers on condition that their reflectance (paper backing) is greater than 20% and their diffuse opacity (paper backing) is greater than 45% (1).The method is not suitable for highly transparent papers such as glassine.This method employs d/0 geometry, illuminant C, and paper backing whereas TAPPI T 425 "Opacity of Paper" employs 15/d geometry, illuminant A, both 89% reflectance backing and paper backing.This method is similar to ISO 2471.