Invisible Patterns, Indiscernible Pigments? Non-Destructive Detection of Painted Cultural Relics Using Hyperspectral Imaging

高光譜成像技術(shù)在彩繪文物的檢測(cè)中具有廣泛的應(yīng)用，它是一種非破壞性的分析方法，可以提供文物表面詳細(xì)的光譜信息，從而幫助研究人員和保護(hù)人員識(shí)別顏料、評(píng)估文物的保存狀況并支持修復(fù)工作。

Hyperspectral imaging technology has extensive applications in the examination of painted cultural relics. As a non-destructive analytical method, it provides detailed spectral information about the surface of artifacts, enabling researchers and conservators to identify pigments, assess preservation conditions, and support restoration efforts.

「顏料識(shí)別 / Pigment Identification」

高光譜成像可以用于識(shí)別彩繪文物中使用的各種顏料。不同的顏料具有的光譜吸收和反射特性，通過建立顏料光譜數(shù)據(jù)庫，可以將文物表面的光譜數(shù)據(jù)與數(shù)據(jù)庫中的標(biāo)準(zhǔn)光譜進(jìn)行匹配，從而確定顏料的種類。這種方法尤其適用于那些肉眼難以區(qū)分的相似顏料的鑒定。

例如，一個(gè)課題組利用高光譜成像技術(shù)分析佛教洞穴繪畫的顏料成分，為文物的保護(hù)和修復(fù)提供科學(xué)依據(jù)。該研究系統(tǒng)建立了包含24種常見礦物顏料（涵蓋紅、白、黃、藍(lán)、綠、黑等色系）的粉末狀態(tài)高光譜反射光譜數(shù)據(jù)庫。

為了更貼近實(shí)際繪畫條件，數(shù)據(jù)庫特別納入了添加動(dòng)物膠粘合劑（1:1比例）后的顏料光譜，因?yàn)檠芯堪l(fā)現(xiàn)膠粘合劑會(huì)顯著改變光譜特征（如：可能導(dǎo)致原始吸收峰消失或產(chǎn)生新的吸收峰）。

Hyperspectral imaging can identify various pigments used in painted cultural relics. Different pigments exhibit unique spectral absorption and reflection characteristics. By establishing a pigment spectral database, the spectral data from artifact surfaces can be matched with standard spectra in the database to determine pigment types. This method is particularly useful for distinguishing visually similar pigments that are difficult to differentiate with the naked eye.

For example, one research team utilized hyperspectral imaging to analyze the pigment composition of Buddhist cave paintings, providing a scientific basis for artifact conservation and restoration. The study systematically established a hyperspectral reflectance database for 24 common mineral pigments (covering red, white, yellow, blue, green, black, and other color systems) in powdered form.

To better approximate actual painting conditions, the database specifically included spectra of pigments mixed with animal glue binder (1:1 ratio), as research showed that binders significantly alter spectral features (e.g., causing original absorption peaks to disappear or generating new ones).

顏料粉末與膠混合后，分別涂布在紙板和石材上

The powder and glue are mixed and applied to the cardboard and the stone.

粉末與粉末混合膠的對(duì)比：(a) *色；(b) 沙漠棕褐色；(c) 藍(lán)花色；(d) 綠松石綠色

Spectral comparison of powder and powder mixed glue: (a) cinnabar; (b) desert tan color; (c) blue flower color; (d) turquoise green color.

「材料評(píng)估 / Material Evaluation」

高光譜成像可用于評(píng)估彩繪文物的材料構(gòu)成。通過分析文物表面的光譜數(shù)據(jù)，可以識(shí)別出不同的材料，如顏料、粘合劑和保護(hù)涂層。這對(duì)于了解文物的制作工藝和材料來源具有重要意義。

一項(xiàng)針對(duì)斯洛文尼亞彩繪蜂巢木板畫的研究，系統(tǒng)性地應(yīng)用了不用波段的高光譜成像系統(tǒng)。這充分發(fā)揮了不同波段的優(yōu)勢(shì)：

VNIR提供高分辨率顏色分布，SWIR對(duì)有機(jī)黏合劑（如干性油）的化學(xué)基團(tuán)（如酯羰基、亞甲基）振動(dòng)特征敏感，其典型吸收峰在~1940nm和2300~2330nm區(qū)域，成功區(qū)分了視覺顏色相似但化學(xué)成分不同的區(qū)域。

Hyperspectral imaging can assess the material composition of painted cultural relics. By analyzing surface spectral data, different materials such as pigments, binders, and protective coatings can be identified. This is crucial for understanding the craftsmanship and material origins of artifacts.

A study on Slovenian painted beehive panels systematically employed hyperspectral imaging systems across different spectral bands, leveraging the advantages of each:

VNIR provided high-resolution color distribution. SWIR was sensitive to vibrational characteristics of chemical groups (e.g., ester carbonyl, methylene) in organic binders like drying oils, with typical absorption peaks at ~1940 nm and 2300–2330 nm, successfully distinguishing areas with similar visual colors but different chemical compositions.

主成分分析(PCA)結(jié)果，左：可見近紅外(VNIR，400-1000nm)波段，中：近紅外(NIR，900-1700nm)波段，右：短波紅外(SWIR，900-2500nm)波段

Principal Component Analysis (PCA) results: left: Visible and Near-Infrared (VNIR, 400-1000 nm) band; center:  Near-Infrared (NIR, 900-1700 nm) band; right: Short-Wave Infrared (SWIR, 900-2500 nm) band.

「繪制圖案分析 / Pattern Analysis」

高光譜成像技術(shù)可以用于分析彩繪文物的繪制圖案。通過對(duì)高光譜圖像進(jìn)行處理，如主成分圖像選擇、移動(dòng)最小二乘法（MLS）和圖像融合等方法，可以提取彩繪文物上的繪制圖案，發(fā)現(xiàn)肉眼難以觀察到的隱藏信息，這種方法對(duì)于研究古代繪畫技巧和文化具有重要意義。

例如，針對(duì)秦陵二號(hào)銅車馬表面嚴(yán)重受損的"夔(Kuí)龍紋"（存在顏料脫落、銅銹覆蓋和變色三類損傷），研究采用近紅外高光譜成像（900-1700nm）技術(shù)。通過分析發(fā)現(xiàn)，1450nm附近是顏料邊緣的顯著吸收谷，在此波段下拍攝的高光譜圖像能清晰顯示肉眼不可見的紋飾邊緣，顯著克服了銅銹覆蓋和顏料脫落的干擾。

Hyperspectral imaging can analyze painted patterns on cultural relics. Through processing techniques such as principal component image selection, Moving Least Squares (MLS), and image fusion, hidden details invisible to the naked eye can be extracted. This method is highly valuable for studying ancient painting techniques and cultural significance.

For instance, in examining the severely damaged "Kuilong pattern" on the No. 2 Bronze Chariot of the Qin Mausoleum (affected by pigment flaking, bronze rust coverage, and discoloration), near-infrared hyperspectral imaging (900–1700 nm) was employed. Analysis revealed a significant absorption trough near 1450 nm at pigment edges. Hyperspectral images captured at this wavelength clearly displayed pattern edges obscured by rust or pigment loss, overcoming interference from these factors.

光譜采集區(qū)域 / The picture of the gathering area

"夔龍紋"邊緣區(qū)域光譜曲線域

The spectral curve of the edge areas in the “Kuilong" pattern

(a)、(b)： 經(jīng)高通濾波器增強(qiáng)的高光譜圖像，及其邊緣提取結(jié)果

(c) 、(d)：經(jīng)圖像校正后的普通光學(xué)圖像，及其邊緣提取結(jié)果

(e)：圖(b)與(d)邊緣信息的融合結(jié)果

(a), (b): Hyperspectral image enhanced by high-pass filter and its edge extraction result

(c), (d): Corrected conventional optical image and its edge extraction result

(e): Fusion result of edge information from (b) and (d)

「科技賦能，續(xù)寫文明 / Technology Empowering Cultural Continuity」

高光譜成像技術(shù)，如同一把無損的“文物解碼器"，為彩繪文物的研究與保護(hù)開辟了新的視角，在揭示顏料信息、鑒別材料組成、再現(xiàn)歷史紋飾方面展現(xiàn)出強(qiáng)大的能力。

精準(zhǔn)探測(cè)，源于好的設(shè)備。要充分發(fā)揮高光譜技術(shù)的潛力，穩(wěn)定可靠、性能優(yōu)異的設(shè)備至關(guān)重要。我司提供寬廣波段的高光譜成像儀，可集成至便攜式、實(shí)驗(yàn)室臺(tái)架等多種系統(tǒng)，為文化遺產(chǎn)現(xiàn)場(chǎng)與實(shí)驗(yàn)室檢測(cè)提供無損、精準(zhǔn)、高效的整體解決方案。

隨著數(shù)據(jù)處理方法、光譜數(shù)據(jù)庫的完善以及多技術(shù)協(xié)同應(yīng)用的深入，這項(xiàng)技術(shù)將會(huì)在文化遺產(chǎn)保護(hù)領(lǐng)域扮演越來越關(guān)鍵的角色，為守護(hù)和傳承人類瑰寶貢獻(xiàn)重要力量。

Hyperspectral imaging, like a non-destructive "artifact decoder," opens new perspectives for the research and conservation of painted cultural relics. It demonstrates remarkable capabilities in revealing pigment information, identifying material compositions, and reconstructing historical patterns.

Precision detection stems from exceptional equipment. To fully realize the potential of hyperspectral technology, stable, reliable, and high-performance instruments are essential. Our company offers broad-band hyperspectral imagers that can be integrated into portable, laboratory bench, and other systems, providing non-destructive, accurate, and efficient solutions for both on-site and laboratory cultural heritage examinations.

As data processing methods improve, spectral databases expand, and multi-technique collaborations deepen, this technology will play an increasingly critical role in cultural heritage conservation, contributing significantly to the preservation and transmission of human treasures.

案例來源 / Source：

1. Shi, X., Lin, X., Lei, Y., Wu, J., Lv, X., & Zhou, Y. (2024). A study on pigment composition of Buddhist cave paintings based on hyperspectral technology. Materials, 17(21), 5147.

2. Sandak, J., Sandak, A., Legan, L., Retko, K., Kav?i?, M., Kosel, J., Poohphajai, F., Diaz, R. H., Ponnuchamy, V., Sajin?i?, N., Gordobil, O., Tavzes, C., & Ropret, P. (2021). Nondestructive evaluation of heritage object coatings with four hyperspectral imaging systems. Coatings, 11(2), 244.

3. Han, D., Ma, L., Ma, S., & Zhang, J. (2019). Discovery and extraction of surface painted patterns on the cultural relics based on hyperspectral imaging. Journal of Physics: Conference Series, 1237(3), 032028.