Analyzing stains on calligraphy and painting using hyperspectral imaging

Paper relics is an important carrier of Chinese culture, the calligraphy and painting, as a kind of paper relics, has high value on historical and cultural to us, so the research on calligraphy and painting has been one of the important contents to conservation researchers. The material of the calligraphy and painting mostly is silk or paper, which both are vulnerable to natural and human factors, and one of the damages is stain. Hyperspectral imaging technique, which records spectral and spatial information at the same time about an object, is also a non-invasive technique with wide range of spectral response and high spectral resolution. In this article, this technique is used to enhance the visibility and support a quantitative evaluation of stains by post-processing with two different methods, the density slice of single band image and supervised classification with SAM (spectral angle mapping) of multi bands image combining the image processing software (ENVI),which is able to count the number of stain pixels, providing quantitative assessment of the calligraphy and painting condition of staining.