基于视觉的答题卡自动判分系统设计  

Design of Automatic Judgment System of Answer Card Based on Vision

作　　者：程淑红[1] 尚果超 CHENG Shu-hong;SHANG Guo-chao(College of Electric Engineering,Yanshan University,Qinhuangdao,Hebei 066004,China)

机构地区：[1]燕山大学电气工程学院,河北秦皇岛066004

出　　处：《计量学报》2018年第6期804-810,共7页Acta Metrologica Sinica

基　　金：国家自然科学基金(61601400);河北省博士后基金(B2016003027);秦皇岛市科学技术研究与发展计划(201701B009)

摘　　要：针对目前市场上光标读卡机在功能和价格上的局限性,提出了基于数字图像处理的答题卡识别新方法。首先将答题卡进行图像预处理和图形校正,利用YCb Cr颜色空间算法分割出考生信息区和答题区;然后利用字符匹配和纵向同步头定位出考生信息区和答题区的精确坐标;最后利用自适应阈值算法把答题卡二值化,计算二值图像中每个填涂点的面积并与设定的阈值比较,若大于阈值,则视为已填涂。实验证明:该方法具有识别速度快、准确率较高的特点,并且对于答题卡扫描时的倾斜不敏感,对填涂大小、填涂深浅不一致和卷面轻微污损等情况均有比较好的识别效果。Aiming at the limitation of function and price of cnrsor reader in the current market, a new method of answer cards recognition based on digital image processing is proposed. Firstly, the answer card is used for image pre- processing and graphic correction and the YCbCr color space algorithm is used to split out the candidate information area and answer information area. Then, the character matching and vertical synchronization-strips are used to locate their specific coordinates. Finally, the adaptive threshold algorithm is used to binarize the answer card and calculate the each filling area in binary image. Comparing the area with the set threshold, if it is bigger than set threshold, it will be regarded as having been filled. Experiments show that the method has higher recognition speed and accuracy. What＇ s more, it is not sensitive to the tilt of answer cards when scanning, and it has a better recognition effect on the size of the filling area, the unbalanced paintings, and the slight stains on answer cards, etc.

关 键 词：计量学 答题卡识别 视觉 图像处理 YCBCR颜色空间 字符匹配 自适应阈值分割 

分 类 号：TB96[机械工程—光学工程]