Indigo blue is a natural organic color from the Indigofera tinctoria plant. It is insoluble in water and does not require mordant to fix the color; therefore, due to its nature it can be considered as a pigment or dye. The identification of indigo in cultural heritage is very difficult due to the complexity of its chemical formula and the changes that it can undergo in certain conservation and exposition conditions. For this reason, characterization of possible degradation, transformation, and reaction processes is essential for its identification. In this study, multispectral imaging has been used for the first time as noninvasive technique to characterize the aging state of indigo blue using samples aged in a controlled climate chamber under extreme conditions of humidity, temperature, and light. The technique has proven to be very promising for this application, together with classification techniques based on machine learning approaches.

中文翻译：

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用多光谱成像表征靛蓝的演变

靛蓝是来自Indigofera tinctoria的天然有机颜色植物。不溶于水，不需要媒染剂固定颜色；因此，由于其性质，它可以被视为颜料或染料。靛蓝在文化遗产中的鉴定非常困难，因为它的化学式很复杂，而且在一定的保护和展示条件下会发生变化。出于这个原因，可能的降解、转化和反应过程的表征对于其识别是必不可少的。在这项研究中，多光谱成像首次被用作非侵入性技术，使用在极端湿度、温度和光照条件下在受控气候室中老化的样品来表征靛蓝的老化状态。该技术已被证明对该应用非常有前景，