将常见的印刷缺陷分为点、线、面3类，介绍了印刷缺陷在线检测的基本流程，说明了Blob算法检测缺陷的具体步骤，并运用Blob算法结合缺陷面积及周长的特征，成功对印品缺陷进行了提取及归类，最终得到了缺陷的面积、位置、类型等特征参数，在程序中实现了印刷品缺陷的检测。

The common printing defects were divided into point, line and area. The basic flow of online defect test and detailed steps of blob algorithm were introduced. Defects in printed matter were identified and classified by blob algorithm combined with area and girth; characteristic parameters of defects such as area, position and style were extracted. Defect detection of printed matter was achieved in program.