OTSU Guided Adaptive Binarization of CAPTCHA Image using Gamma Correction
Shi Cunzhao; Wang Yanna; Xiao Baihua; Wang Chunheng
2016
会议名称International Conference on Pattern Recognition(ICPR)
会议录名称ICPR
会议日期2016.12.4-2016.12.8
会议地点Mexico
摘要Gamma correction, a nonlinear operation, has long
been used to code and decode luminance or tristimulus values
in video or still image systems [1]. In this paper, we make the
following observations: for CAPTCHA images which could not be
well binarized using the threshold of OTSU, there exists a gamma
corrected image which could be well segmented by the OTSU
threshold and the value of the best gamma could be revealed
by observing the maximal inter-class variance (MICV) values
of different images transformed by different values of gamma.
Concretely, we convert the R, G, B channels of the original
CAPTCHA image with different gamma values and transform
the color images to gray-level images. Each gray-level image could
be then segmented by the threshold acquired by OTSU. By linking
each gamma value with the corresponding maximal inter-class
variance value, we could draw a changing curve of variance
values versus gamma. The best gamma could be acquired by
finding the point whose related MICV starts to change slowly.
Moreover, the polarity of the image could also be revealed by the
changing trend of the curve. Experimental results on different
categories of CAPTCHA images demonstrate the effectiveness of
the observations for binarizing the CAPTCHA images and telling
the polarity as well.

关键词Binarization Gamma Correction Captcha Image
文献类型会议论文
条目标识符http://ir.ia.ac.cn/handle/173211/12088
专题复杂系统管理与控制国家重点实验室_影像分析与机器视觉
通讯作者Shi Cunzhao
推荐引用方式
GB/T 7714
Shi Cunzhao,Wang Yanna,Xiao Baihua,et al. OTSU Guided Adaptive Binarization of CAPTCHA Image using Gamma Correction[C],2016.
条目包含的文件 下载所有文件
文件名称/大小 文献类型 版本类型 开放类型 使用许可
root.pdf(1894KB)会议论文 开放获取CC BY-NC-SA浏览 下载
个性服务
推荐该条目
保存到收藏夹
查看访问统计
导出为Endnote文件
谷歌学术
谷歌学术中相似的文章
[Shi Cunzhao]的文章
[Wang Yanna]的文章
[Xiao Baihua]的文章
百度学术
百度学术中相似的文章
[Shi Cunzhao]的文章
[Wang Yanna]的文章
[Xiao Baihua]的文章
必应学术
必应学术中相似的文章
[Shi Cunzhao]的文章
[Wang Yanna]的文章
[Xiao Baihua]的文章
相关权益政策
暂无数据
收藏/分享
文件名: root.pdf
格式: Adobe PDF
所有评论 (0)
暂无评论
 

除非特别说明,本系统中所有内容都受版权保护,并保留所有权利。