Hyperspectral imaging (HSI) is a non-destructive technique that can collect and analyze the spectral and spatial features of cultural relics simultaneously. It supports high spectral resolution and a wide band range. While collecting a large number of spectral images, it can also display the continuous spectrum of each picture element. Therefore, this technique can provide highly effective data for the research and conservation of cultural relics. However, the hyperspectral scanning system currently used on cultural relics is still faced with many challenges, such as hazardous light source, small scanning range, poor intelligence and lack of software designed for cultural relics, which hinder the wider and deeper application of the technique on cultural relics. To tackle the challenges, the Joint Laboratory has developed a hyperspectral scanning system for cultural relics and has begun to study its application. Based on this, the lab is also developing standards for HSI result analysis.

System Building

Develop large-surface flatbed and upright auto-scanning systems, which adopt a common optical path design for visible near-infrared and short-wave infrared spectral bands with a valid spectrum range of 400 -2500nm. Design and develop hyperspectral image analysis software for cultural relics with functional modules like spectral library construction, pigment extraction and line drawing extraction, so as to support the quick collection and analysis of hyperspectral data.

Flatbed auto-scanning system                                        Upright auto-scanning system

Applications

The HSI technique can be used to learn about the “hidden” information of cultural relics and the distribution of their compositions, and thus can be applied to disease investigation of cultural relics like calligraphy and paintings, murals, painted sculptures and bronze vessels, studies on the painting techniques of painted cultural relics like line drawing extraction and pigment identification, and aging evaluation for some cultural relics made from organic materials.

Hidden diseases of the painted ceiling at the Donghua Gate of the Forbidden City (From left to right: original image, 1,300nm image, 2,400nm image)

Extract line drawings from calligraphy and paintings, and obtain information on the spatial distribution of pigments

Creation of Standards

The lab works on the industry standards for the “Hyperspectral Analysis Method for Cultural Relics” to promote the application of the HSI technique on cultural relics.

Studying the light source parameters in the hyperspectral analysis method