敦煌壁画颜料颜色非接触式测量条件优化研究

针对敦煌壁画颜料颜色的非接触式测量,以接触式颜色测量设备测得的光谱数据为参考,利用非接触式测量设备PR705光谱辐射度计,在不同照明和测量距离条件下,测量敦煌壁画色卡的光谱数据,并通过计算得到不同照明和测量距离条件下色块样本的光谱均方根(RMS)误差和色差(?E),以此作为评价测量结果的参数,通过优化拟合方法获得这两个指标关于照明和测量距离的函数关系,进而分析照明和测量距离对颜色测量精度的影响,从而实现测量条件的优化,提高颜色测量精度。研究结果表明,测量距离为0.5~1.0 m和2.0~2.5 m、照明距离为3.0~3.5 m的条件下,测量结果与参考值的RMS和?E均较小,可获得较好的测量精度,且光谱误差RMS0.006,色差?E0.5。

Optimization Study on the Condition of Non-Contact Color Measurement of Dunhuang Mural Pigment

Aimed at the non-contact color measurement of Dunhuang mural pigment, by taking reference from the spectroscopic data of contact color measurement devices, non-contact device PR705 for spectral radiosity was used to measure the spectroscopic data of Dunhuang murals with the condition of different illumination and measure distances. The calculated RMS and E of the color charts with different illumination and measure distances were used as the parameters for evaluation, the functional relationship between them was obtained by optimal fitting. The effects of measure distance and illumination on accuracy of pigment measurement were analyzed in order to realize the optimization of measuring condition and enhance the measurement accuracy. The results showed that performance of measurement accuracy was optimal when measurement distance was in the range of 0.5~1.0 m and 2.0~2.5 m, with the illumination distance in the range of 3.0~3.5 m, while the RMS and E reached the minimum, with RMS less than 0.006, E less than 0.5.