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多光谱摄影图像调查技术,基于不同物质对不同光谱吸收与反射的差异及不同波段单色光谱有相应的灰度偏向,以单色光谱灰度图像经伪彩色强化,可作为一种绘画材料普查方法。这种方法的应用首先需要建立相关遗址绘画材料多光谱图像标准,以此为基础才可以通过多光谱伪彩色等图像对壁画中漫漶壁画、相近色相颜料及无法观察的有机材料做前期普查,为后期高精度仪器的进一步调查提供参考。采用已知敦煌壁画中常用29种绘画材料制作标准颜料色板,通过规范多光谱拍摄程序和优化多光谱拍摄条件,在250~1 300nm之间获取各种颜料在不同光谱区域的反射及荧光图像,再经过后期科学的图像校正及红外、紫外反射伪彩色图像合成,初步建立敦煌壁画颜料多光谱图像标准数据库。对真实壁画进行多光谱拍摄,将获取的可见反射、红外反射伪彩色和紫外反射伪彩色图像与标准数据库图像进行交叉对比,并采用便携式显微镜、便携式X荧光、近红外光谱等分析技术验证所获取的多光谱分析结果,表明壁画颜料多光谱图像标准数据库的建立,作为一种新型无损检测辅助方法,可通过多光谱图像对敦煌壁画颜料前期鉴别、推断绘画材料属性以及获取颜料分布状况等信息。绘画材料光谱图像数据库的建立可提高常见绘画材料类别及范围的前期调查效率和可靠性,是一种有效的颜料面集调查辅助方法。
Multi-spectral photographic image survey techniques, based on different substances on different spectral absorption and reflection differences and different bands of monochromatic spectra have the corresponding gray-scale, single-color spectral gray image by pseudo-color enhancement can be used as a drawing material method. The application of this method first needs to establish the multi-spectral image standard of related site painting materials. Based on this, pre-census of murals, similar hue pigments and unobservable organic materials in murals can be done through multi-spectral pseudo-color images. Later high-precision instruments for further investigation provide a reference. By using 29 kinds of painting materials commonly used in Dunhuang frescoes to produce standard pigment swatches, the specular and fluorescent images of various pigments in different spectral regions can be obtained by standardizing multispectral photographing procedures and optimizing multispectral photographing conditions between 250 and 1 300 nm , And then through post-scientific image correction and infrared, ultraviolet reflection pseudo-color image synthesis, the initial establishment of Dunhuang mural pigment multispectral image standard database. Multi-spectral shooting of the real murals was carried out. The acquired pseudo-color images of visible reflex, infrared reflex pseudo-color and ultraviolet reflex were compared with standard database images. The obtained data were verified by portable microscope, portable X-ray fluorescence and near infrared spectroscopy The results of multispectral analysis indicate that the establishment of a standard database of mural pigment multispectral images can be used as a new non-destructive testing aided method by multi-spectral images of Dunhuang mural pigment identification, inference of the material properties of paint and access to information such as pigment distribution. The establishment of spectral database of painting materials can improve the efficiency and reliability of preliminary investigation of common types and ranges of painting materials, and is an effective method for investigation of pigment surface area.