印鉴自动识别中一种新的图像预处理方法

A New Approach to Preprocessing of Image for Auto-identification of Seal Imprint

印鉴自动识别是计算机图像处理和模式识别技术的重要应用,而自动识别的效果直接取决于印鉴图像的前期处理。本文对印鉴自动识别中预处理的各个阶段进行了仔细研究,并给出一系列相关算法。在这些预处理中还充分考虑到了有复杂背景情况下的处理。利用灰度直方图二值化,对于有背景的印鉴采用三峰去阈值;利用水平和垂直投影获取印鉴的最大外接矩形,去除影响印鉴形状的噪音;基于印鉴最大外接矩形的四边角印鉴像素的统计特征,判别印鉴的形状,计算量小同时识别正确率能达到实用;利用形状特征通过扫描得到形状关键点,分离印鉴边框和印鉴内容;通过XY坐标转换为极坐标,把印鉴之间的旋转匹配变为水平移动匹配,减少了计算量同时提高了配准的精度。印鉴通过该快速预处理方法,为后期的识别打下了很好的基础,大大提高了正确识别率。

The auto - identification of Seal imprint is one of the important applications in the field of image processing and pattern recognition, and that, the result of auto - identification depends on the preprocessing of seal imprint image. In the paper, every phase of the preprocessing including binary - image, removing the white edge, recognizing the shape, getting the frame of the seal imprint, computing the rotated angle, is discussed and studied carefully, and a corresponding series of algorithms is presented. At the same time, the complex backgrounds in seal imprint are considered fully. By the method with the character of high processing speed, it＇ s easy for the seal imprint to be identified latter and improve the correct probability of the seal imprint auto - identification.