基于高光谱成像技术的涂抹掩盖字迹识别方法研究

Research on Identification Method of Covered Handwriting Based on Hyperspectral Imaging Technology

在刑事案件和民事案件中,许多重要文件中的签名、日期、数字等字迹常常被有意涂抹而掩盖其真实信息,因而无法作为证据使用。因此,开展高光谱成像技术(450~950 nm)快速无损显现涂抹掩盖字迹十分必要。涂抹掩盖字迹中,黑色签字笔作为书写及涂抹工具占多数,因此从21种黑色签字笔中随机选取两种进行相互涂抹作为样本。同时,选取墨水中含有碳元素和不含有碳元素的黑色签字笔各两支,用同一支笔书写字迹并进行涂抹掩盖作为样本。实验结果表明,用高光谱成像技术在450~950 nm波长范围内进行显现肉眼无法辨别的涂抹掩盖字迹,大部分被涂抹掩盖的字迹能够得到完整、清晰的显现,反映出被掩盖字迹的真实形态与信息,具有良好的显现效果。部分显现效果不佳,原书写字迹细节特征残缺,但能识别出原字迹,还有少部分较为模糊,无法达到检验要求。而使用传统红外显现方法时,大部分涂抹掩盖字迹难以显现。

In criminal and civil cases, signatures, dates, numbers, and other handwritings of several important documents are deliberately covered to conceal the real information such that they cannot be used as evidence.Therefore, it is necessary to study the feasibility of hyperspectral imaging technology(approximately 450–950nm) for rapid and non-destructive identification of covered handwriting. Black handwriting pens are mostly used such that two pens are randomly selected from 21 kinds of black handwriting pens to cover each other as samples. Simultaneously, two kinds of black handwriting pens with carbon in the ink and two kinds of black handwriting pens without carbon in the ink are selected, and the same pen is used to write and cover by itself as a sample. The experimental results show that most of the covered handwriting can be completely and clearly identified using hyperspectral imaging technology in the band of approximately 450–950 nm with the real shape and information, which has a good effect. Part of the identification effect is not good, and the details of the original handwriting are incomplete, but the original handwriting can be recognized. In addition, few parts are blurred, which cannot meet the identification requirements. However, most of the covered handwriting is difficult to develop using the traditional infrared method.