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. 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. 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. 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.