成像光谱技术的古画隐藏信息提取

Hidden information extraction from the ancient painting using hyperspectral imaging technology

目的古画隐藏信息是包含在画作中的一种微弱信息,对于文物鉴定与修复具有非常重要的意义,如何快速无损准确提取古画中微弱的隐藏信息是目前研究和应用的一大技术难题,本文利用高光谱成像技术快速无损提取古画隐藏信息。方法对古画进行高光谱扫描成像,得到短波红外波段(1 000 2 500 nm)的高光谱立方体数据,联合多种光谱匹配技术分析古画中人物头冠颜料种类;利用主成分分析技术,提取古画头冠周围涂抹痕迹。结果通过多种光谱匹配算法对颜料进行分析,确定了颜料种类,并对匹配算法进行了对比,结果表明在颜料混合的情况下,光谱匹配算法仍能够有效的识别出混合颜料的端元种类,光谱信息散度与光谱角的匹配算法SID_SA匹配精度可以达到0.096,相比其他匹配算法,效果最好;利用主成分分析技术分层剥离主要背景信息后,头冠周围位于画作底层的涂抹信息得到了加强,可以有效地区分背景颜料信息与涂抹信息,提取隐藏信息。结论高光谱分析技术对古画隐藏信息的提取有很好地识别效果,能够准确提取绘画颜料种类,发现绘画过程中的涂抹等痕迹,特别适用于混合颜料的种类识别与画作底层信息提取,发掘画作隐藏信息,为文物保护修复与鉴定提供支持。

Objective The hidden information of ancient painting is a kind of weak information contained in the culture relics,such as the smearing information,hidden text information,and post-repair information.It may reflect the process of painting,and then we can explore the deep information of the ancient paintings,which is very helpful for the restoration and identification of cultural relics.The hidden information can also provide a new way for us to know more about the culture relics.Traditional identification work for ancient paintings mainly rely on experienced cultural relics identification personnel.Based on their experience,they usually make a judgment to the ancient painting according to the material,creative style,age,and other information to identify.It is with high requirement for staff technical requirements in traditional cultural relics identification methods.Beyond that,this method is inefficient and prone to errors.Thus,quick and effective extraction of the weak hidden information in ancient paintings in a non-destructive method is a desirable technique problem for research and application.Hyperspectral imaging technology takes full advantage of its spectral characteristics,so its extraction accuracy is higher than other imaging method.This paper aims to study how to use hyperspectral imaging technology quickly and intuitively extract the hidden information of ancient paintings.Method For the difficulty of ancient paintings＇ hidden information extraction,only a few scientific instruments are available for the extraction of ancient painting information.We use the hyperspectral imaging spectrometer to scan the painting to obtain the short-wave infrared hyperspectral data（1 000~2 500 nm）.Then,spectral correlation coefficient matching algorithm（SCM）,spectral information divergence（SID）,and matching algorithm based on spectral information divergence and spectral angle mixing method（SID_SA） is used according to the spectral angle matching algorithm（SAM） to analyze the crown＇s pigment.The modified information of the crowns are extracted by principal component analysis.Result To determine the composition of the brown pigment in the crowns,the spectrum of the brown pigment was analyzed by a variety of spectral matching algorithms with the established standard spectrum of the ancient pigments.The brown pigment contains the ocher component and the distributions of the carbon black pigment and the ocher pigment vary with the different proportions of the position.The reason for this may be related to the deployment of the pigment when it has been painting,so the proportion of the pigment in the different painting areas is different,resulting in different crowns for spectral mixing phenomenon.The pigments are analyzed by a variety of spectral matching algorithms to determine the types of the pigments.The matching algorithms are compared,then we find the mixed pigments.After the main pigment information is peeled off,the modified information is enhanced to extract effectively.Results show that according to the spectral feature of the pigments,spectral matching algorithms can effectively identify the end element of the mixed pigment in the case of pigments mixing.Compared with other algorithms,the matching algorithm of spectral information divergence and the matching accuracy of the spectral information divergence and the spectral angle SID_SA can reach 0.096,compared with other matching algorithms;thus,its effect is the best.After the main background information is separated by the principal component analysis technique,the smearing information around the crowns,which are located at the bottom of the painting,can be enhanced.This method can effectively distinguish the background pigments information and smear information,and extract the hidden information.Conclusion Hyperspectral analysis technology can get a good recognition result on the extraction of hidden information of ancient paintings,and can accurately extract the types of paint pigments and find the traces of painting.It is especially suitable for the identification of mixed pigments and the underlying information of paintings.Certain pigment colors and hidden information can be enhanced for effective extraction using hyperspectral imaging processing techniques.The shortwave infrared imaging spectrometer may play an important role in the production of digital archives and in the analysis and restoration of cultural relics,thus promoting the development of digital work associated with cultural relics.This method can provide support for the restoration and identification of heritage conservation.