Study On Color Correction Of Dunhuang Mural Reproduction

Dunhuang mural color correction is a hot problem all along when it is reproduced or reappeared on different equipment (medium), it is one of the important indexes on cultural relic protection, achieving the same color reappearance along with the Dunhuang mural transferred, is also an important part of Dunhuang study.By analyzing the color correction method from digital camera to CRT, and from CRT to color printer, the color correction system is established, which can be operated practically under a big color gamut. After transferred through the whole system equipment, which included taking picture with digital camera, computer processing and color copying, the final picture we got from color printer can show the original mural color accurately.Based on the study of color gamut matching method in existence, the matching method of artificial neural network is adopted. With the optimization design and the training of the artificial neural network, ample information is stored in weight and threshold value of the artificial neural network. The color gamut matching is realized from the L*a b color space of the color printer to RGB color space of the CRT, this method can avoid the deficiency of other, and get better forecasting value of color gamut matching.Because of no theory or principle to decide the number of hide-layer neural cell of the artificial neural network, the method combined second general revolving combination design with genetic algorithm is put forward, which can optimize the hide-layer neural cell number of artificial neural network. This method provided theory foundation for the structure establishment of hide-layer neural cell of artificial neural network also.The artificial neural network including two hide-layers is established, which can correct the tristimulus values, the weight and threshold value of this artificial neural network is gained, and the artificial neural network is nested in the computer program compiled by VC language. The color correction of the last Dunhuang mural picture can be finished after the tristimulus values of image pixel are corrected, and the process simplified correcting the complex color distortion has been realized.Using Macbeth ColorChecker Chart, the color difference of this color correction system is tested. Before correction, average color difference is 17.1 NBS, the maximum color difference is 37.0 NBS, and the minimum color difference is 4.3NBS;while after correction, the average color difference is reduced to 5.3 NBS, the maximum color difference is 12.4 NBS, and the minimum color difference is 1.7 NBS. Ideal objective effect of color correction has been gotten and expert in this domain has praised the work.