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

高光譜成(chéng)像技術在彩繪(huì)文物(wù)的檢測(cè)中具(jù)有廣泛的(dí)應用(yòng)，它(tā)是(shì)一種非破壞(huài)性的(dí)分析方(fāng)法，可以提(tí)供文(wén)物表麵詳(xiáng)細的(dí)光(guāng)譜(pǔ)信(xìn)息，從而幫(bāng)助研究人(rén)員和(hé)保護人(rén)員(yuán)識(shí)別顏(yán)料，評(píng)估(gū)文物的(dí)保存(cún)狀(zhuàng)況(kuàng)並支(zhī)持(chí)修(xiū)復工作。

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(yán)料識(shí)別(bié) / Pigment Identification」

高光譜(pǔ)成像(xiàng)可(kě)以用(yòng)於識別(bié)彩繪文物(wù)中使用(yòng)的各種顏(yán)料(liào)。不同的(dí)顏料具有的(dí)光(guāng)譜吸收(shōu)和反射特(tè)性，通(tōng)過建立顏料光譜數(shù)據(jù)庫(kù)，可以將文物(wù)表(biǎo)麵的(dí)光(guāng)譜數(shù)據與數(shù)據(jù)庫中(zhōng)的標(biāo)準光譜(pǔ)進(jìn)行(háng)匹(pǐ)配，從而(ér)確定顏料(liào)的(dí)種類。這種方(fāng)法(fǎ)尤其(qí)適用(yòng)於(yú)那些肉(ròu)眼難以(yǐ)區(qū)分的相似(sì)顏料(liào)的(dí)鑒定。

例(lì)如(rú)，一個課(kè)題(tí)組利用高(gāo)光譜成(chéng)像(xiàng)技(jì)術分析(xī)佛教(jiào)洞(dòng)穴繪(huì)畫的顏(yán)料(liào)成分，為文(wén)物的保(bǎo)護和修復(fù)提供科(kē)學依據。該(gāi)研(yán)究係統(tǒng)建(jiàn)立(lì)了(liǎo)包含(hán)24種常見(jiàn)礦物顏料（涵蓋(gài)紅，白(bái)，黃，藍(lán)，綠，黑(hēi)等(děng)色係(xì)）的粉末(mò)狀態(tài)高光(guāng)譜反射光(guāng)譜數據(jù)庫。

為(wéi)了(liǎo)更貼近(jìn)實際繪(huì)畫條(tiáo)件，數據(jù)庫特別(bié)納(nà)入了添加動(dòng)物(wù)膠(jiāo)粘合(hé)劑(jì)（1:1比(bǐ)例(lì)）後的(dí)顏料光(guāng)譜(pǔ)，因(yīn)為研究(jiū)發現膠粘(nián)合(hé)劑會顯(xiǎn)著(zhù)改變(biàn)光譜(pǔ)特(tè)征（如：可(kě)能導致原始(shǐ)吸(xī)收(shōu)峰(fēng)消失(shī)或產生(shēng)新(xīn)的吸收(shōu)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(liào)粉(fěn)末與膠混合後，分別塗布(bù)在(zài)紙板(bǎn)和(hé)石(shí)材上

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

粉末與(yǔ)粉(fěn)末混合膠(jiāo)的(dí)對(duì)比：(a) *色；(b) 沙(shā)漠棕褐色(sè)；(c) 藍花(huā)色(sè)；(d) 綠鬆(sōng)石綠色(sè)

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

「材料評估(gū) / Material Evaluation」

高光譜(pǔ)成(chéng)像可用於評估彩繪(huì)文物的(dí)材料(liào)構成。通過(guò)分(fēn)析文(wén)物表(biǎo)麵(miàn)的光譜數據，可以識(shí)別(bié)出不同的材料(liào)，如顏料(liào)，粘合(hé)劑和保(bǎo)護(hù)塗(tú)層(céng)。這(zhè)對(duì)於(yú)了解(jiě)文(wén)物(wù)的製(zhì)作工藝和(hé)材料來源(yuán)具(jù)有重要意義(yì)。

一(yī)項針對(duì)斯(sī)洛文(wén)尼亞(yà)彩繪(huì)蜂(fēng)巢木板(bǎn)畫(huà)的研究，係統性(xìng)地(dì)應(yīng)用了(liǎo)不用(yòng)波段的(dí)高光譜成(chéng)像(xiàng)係統。這充分發(fā)揮了不(bù)同波段(duàn)的(dí)優勢(shì)：

VNIR提供高分辨(biàn)率顏色分(fēn)布(bù)，SWIR對(duì)有機黏合劑(jì)（如幹性(xìng)油）的(dí)化(huà)學(xué)基團（如(rú)酯(zhǐ)羰(tāng)基(jī)，亞(yà)甲(jiǎ)基(jī)）振動特(tè)征(zhēng)敏感(gǎn)，其典型吸(xī)收峰在~1940nm和(hé)2300~2330nm區域，成功(gōng)區分(fēn)了視覺顏色相似(sì)但(dàn)化學(xué)成分不同的區(qū)域(yù)。

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(zhǔ)成分分析(xī)(PCA)結(jié)果，左(zuǒ)：可見近(jìn)紅(hóng)外(VNIR，400-1000nm)波段，中(zhōng)：近紅(hóng)外(wài)(NIR，900-1700nm)波段，右：短波紅(hóng)外(wài)(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(huì)製(zhì)圖(tú)案(àn)分析(xī) / Pattern Analysis」

高光譜成(chéng)像技(jì)術可以(yǐ)用(yòng)於分(fēn)析彩繪(huì)文(wén)物的(dí)繪製圖(tú)案。通過(guò)對高光譜圖像(xiàng)進行處理，如(rú)主(zhǔ)成分(fēn)圖像(xiàng)選擇，移動(dòng)最(zuì)小(xiǎo)二乘(chéng)法（MLS）和(hé)圖像融(róng)合(hé)等(děng)方法，可(kě)以(yǐ)提(tí)取彩繪文物(wù)上(shàng)的繪(huì)製圖案(àn)，發現(xiàn)肉眼(yǎn)難以觀(guān)察到的(dí)隱(yǐn)藏信息，這(zhè)種方(fāng)法(fǎ)對(duì)於研(yán)究(jiū)古代(dài)繪畫(huà)技巧(qiǎo)和文(wén)化具有重(zhòng)要(yào)意義(yì)。

例如，針對(duì)秦(qín)陵二號銅車馬表(biǎo)麵(miàn)嚴(yán)重受損的"夔(kuí)(Kuí)龍(lóng)紋"（存在顏料脫(tuō)落(là)，銅鏽(xiù)覆蓋和變色三類損傷），研究(jiū)采用(yòng)近紅(hóng)外高(gāo)光(guāng)譜成(chéng)像(xiàng)（900-1700nm）技(jì)術(shù)。通過(guò)分析發(fā)現，1450nm附(fù)近(jìn)是顏(yán)料(liào)邊緣的(dí)顯著(zhù)吸收穀，在(zài)此波(bō)段下拍(pāi)攝(shè)的高(gāo)光譜圖像能清晰(xī)顯(xiǎn)示肉眼不可(kě)見(jiàn)的(dí)紋飾(shì)邊緣，顯著克服(fú)了銅(tóng)鏽(xiù)覆蓋和(hé)顏(yán)料脫落的幹擾。

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(guāng)譜采(cǎi)集區域 / The picture of the gathering area

"夔龍紋(wén)"邊緣區域(yù)光譜(pǔ)曲綫(xiàn)域

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

(a)，(b)： 經高(gāo)通(tōng)濾波器增強的(dí)高光譜(pǔ)圖像(xiàng)，及其邊(biān)緣提取(qǔ)結(jié)果

(c) ，(d)：經圖(tú)像校正(zhèng)後(hòu)的普通(tōng)光學(xué)圖(tú)像，及其(qí)邊緣(yuán)提取結果

(e)：圖(b)與(d)邊緣信息(xī)的融(róng)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(kē)技賦(fù)能，續寫文(wén)明 / Technology Empowering Cultural Continuity」

高(gāo)光譜(pǔ)成像(xiàng)技術，如(rú)同一(yī)把無(wú)損的(dí)“文物解(jiě)碼(mǎ)器(qì)"，為彩(cǎi)繪(huì)文物的(dí)研(yán)究與(yǔ)保護開辟(bì)了新(xīn)的視角，在揭示顏料信(xìn)息(xī)，鑒(jiàn)別(bié)材料組(zǔ)成，再(zài)現歷史紋飾(shì)方麵(miàn)展現出*的能力(lì)。

精準探測，源於好的(dí)設備(bèi)。要充(chōng)分(fēn)發揮高(gāo)光譜(pǔ)技術的(dí)潛力，穩(wěn)定(dìng)可靠(kào)，性能優異的設備至關(guān)重要(yào)。我司提(tí)供(gōng)寬廣(guǎng)波(bō)段(duàn)的高光(guāng)譜成像儀，可集成(chéng)至便(biàn)攜(xié)式，實(shí)驗(yàn)室(shì)台架等多種係統(tǒng)，為文(wén)化遺產(chǎn)現場與實(shí)驗(yàn)室檢(jiǎn)測(cè)提供無損，精準，高(gāo)效(xiào)的整體解決(jué)方案。

隨(suí)著數(shù)據處理(lǐ)方法(fǎ)，光譜(pǔ)數據(jù)庫(kù)的*以(yǐ)及多技術協(xié)同應(yīng)用的深(shēn)入，這項技術將會(huì)在文化(huà)遺(yí)產(chǎn)保護領(lǐng)域扮(bàn)演越(yuè)來(lái)越(yuè)關(guān)鍵(jiàn)的角(jiǎo)色，為守護和傳承人(rén)類(lèi)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., Kavčič, M., Kosel, J., Poohphajai, F., Diaz, R. H., Ponnuchamy, V., Sajinčič, 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.