Document frauds can occur by the misuse of blank documents by persons who are trusted by the signer or by the adulteration of an official document. The identification of forgery documents by crossing lines requires methods with better accuracy and precision in nondestructive ways. In this sense, this work presented a methodology by applying the partial least squares with discriminant analysis (PLS‐DA) chemometric tool to digital images obtained from a smartphone for crossing lines analysis in two situations: documents that were printed and then signed (the correct mode—Situation 1) and documents that were signed and then printed (fraudulent documents—Situation 2), and by employing blue pen inks types ballpoint, rollerball, gel, and felt‐tip. PLS‐DA models presented a correct classification of all pen types in both situations and presenting sensitivity and specificity equal to 1. Robustness, evaluated by change the printer brand, model, and ink application mode, showed no influence for gel pens. This model was validated by precision estimation at levels of repeatability, intermediary, and reproducibility showing comparable results for the three levels considering the reproducibility with an iPhone 7. Precision at the reproducibility level with iPhone Xs presented the lower value and probably was more effective due to the camera system.

中文翻译：

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具有判别分析的偏最小二乘模型精度：通过交叉线伪造文件的案例研究

文件欺诈可能是由于签名者信任的人滥用空白文件或伪造官方文件造成的。通过交叉线识别伪造文件需要以无损方式具有更高准确度和精确度的方法。从这个意义上说，这项工作提出了一种方法，将偏最小二乘法和判别分析 (PLS-DA) 化学计量学工具应用于从智能手机获得的数字图像，以在两种情况下进行交叉线分析：打印然后签名的文档（正确的模式 - 情况 1) 和签署然后打印的文件（欺诈性文件 - 情况 2），并使用蓝色钢笔墨水类型圆珠笔、滚珠、凝胶和毡尖。PLS-DA 模型在两种情况下都对所有笔类型进行了正确分类，灵敏度和特异性等于 1。通过改变打印机品牌、型号和墨水应用模式来评估的稳健性对中性笔没有影响。该模型通过在重复性、中间和再现性水平上的精度估计进行验证，显示考虑到 iPhone 7 再现性的三个水平的可比结果。 iPhone Xs 在再现性水平上的精度呈现较低的值，并且可能更有效，因为摄像头系统。