Abstract Historical paper often contains features embedded in its structure that are invisible under standard viewing conditions. These features (watermarks, laid lines, and chain lines) can provide valuable information about a sheet’s provenance. Standard methods of reproducing watermarks, such as beta-radiography and low-voltage x-rays, are costly and time intensive, and therefore inaccessible to many institutions or individuals. In this work we introduce an inexpensive prototype whose elements are a light table and a consumer-grade photographic camera. For a given document we acquire an image with light emitted by a light table passing through the document and two images of the front and the back side with ambient light. The images are then processed to suppress the printed elements and isolate the watermark. The proposed method is capable of recovering images of watermarks similar to the ones obtained with standard methods while being a non-destructive, rapid, easy to operate, and inexpensive method.

中文翻译：

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通过抑制遮挡文字或图形对水印进行可见光透射成像

摘要历史论文通常包含嵌入其结构的功能，这些功能在标准查看条件下是不可见的。这些功能（水印，划线和点划线）可以提供有关纸张来源的有价值的信息。再现水印的标准方法，例如β射线照相和低压X射线，既昂贵又费时，因此许多机构或个人都无法使用。在这项工作中，我们介绍了一个便宜的原型，其原型是一个光平台和一台消费级摄影相机。对于给定的文档，我们获取的图像是由光平台发出的光线穿过文档而获得的，正面和背面的两个图像都是环境光。然后处理图像以抑制打印的元素并隔离水印。