印文迭代复印特征变化的实验研究  

Characters' Specifics Changing along with Times of Iterative Copying

作　　者：吴尚[1] 郝红光[2] 韩星周[2] 秦达[2] 

机构地区：[1]中国人民公安大学刑事技术学院,北京100038 [2]公安部物证鉴定中心,北京100038

出　　处：《刑事技术》2016年第2期116-119,共4页Forensic Science and Technology

基　　金：基本科研业务费(No.2015JB013)

摘　　要：目的文件检验实践中,经常遇到检材为复印件的案例。复印件一般会因复印过程而在疵点、形态等特征上较原件存在一定的差异,而不同代次复印件之间的差异通常也不一致。本文以印文为对象,研究分析印文经多次迭代复印后图文特征的变化规律。方法显微放大、比对印文经过多次迭代复印后图文特征的变化;利用Adobe Photoshop中的测量工具测量并记录印文经迭代复印后,在其变化方向上位移量的分布;统计印文的变化位移量并利用SPSS数据分析软件对其进行量化分析。结果随着迭代复印次数的增多,复印件和原件之间的重合度逐渐降低,而笔画和复杂程度又会使文字的图文信息辨识度进一步衰减。结论在迭代复印次数和沿复印文件垂直方向上的位移之间存在着一定程度的线性关系。Objective Copied documents are often come into contact in the field of documents examination. Compared with the original ones, those copied always have continuously increased their differences arisen from the iterative copying because the master copy gradually lost its information along with each time when the preceding copied converted its scanned optical signal into the printed image, causing the copied holding less specifics and configuration than its previous one. Whether a relationship between the copied ones and the master copy is able to deduce from the differences produced as above is of importance. Therefore, a research was in this paper conducted by one photosensitive seal＇s impressed characters as the studied object to investigate the characters＇ specifics changing concomitant to the times of iterative copying. Methods A document was made with the selected photosensitive seal and successively subjected to iterative copying for 15 times. The specific variations were scrutinized through microscopic magnification and compared among each of the iteration-copied documents. The distribution of displacement following the direction of gradual changing between every two consecutive documents produced with the iterative copying, was measured and recorded by the software of Adobe Photoshop. The quantitative analysis was carried out by the software of SPSS based on the statistic amount of the changing displacements. Results The degree of superposition between the copied ones and the seal＇s impression of master copy is decreasing with the times of iterative copying which also result in the further attenuation of character＇s figure-and-stroke information when the relevant word is of more strokes and complexity. Conclusion There is a certainty of linear relationship between the times of iterative copying and the displacements along the vertical direction of the copied documents.

关 键 词：文件检验 印文 迭代复印 位移量 量化分析 

分 类 号：DF794.2[政治法律—诉讼法学]