| At present,more and more attention has been paid to the protection and restoration of the cultural heritage left by ancestors all over the world.Some works of art are unique and precious,and the requirements for preservation and exhibition are very strict.With the development of digital image technology,digital library and digital museum have emerged.Digital image is not only used in advanced scientific research fields,but also in people’s daily life.Cross-media real reproduction of the precious painting works of art in real scenes and then carry out visual storage has become one of the important research work of museums,art galleries and other institutions to exhibit precious cultural heritage and works of art in different non-museum occasions.Studies in cross-media color research have widely used multispectral imaging technology to reconstruct spectral reflectance and make true color reproduction.The research focus of multispectral imaging technology research is spectral reflectance reconstruction.Researchers improve various algorithms to reduce the color difference of the final copied object surface and improve the spectral reconstruction accuracy.The method based on BRDF is to collect the optical characteristics of the object surface with the change of illumination angle,so as to establish a basic function of actual measurement,and calculate the texture,luster,material and other information of the object surface through the function.In combination with a multi spectral imaging system,the computer graphics is used to replicate the artwork across media.In the present research,a combination of Bidirectional Reflection Distribution Function and Multispectral Imaging Technology are applied to the cross-media color reproduction.The study emphasizes on the following aspects:1.The study introduced basic theories related to multispectral imaging technology,including multispectral imaging system and spectral reconstructionalgorithm;the basic theories related to BRDF,including the basic concepts of Optics and radiometry;the definition,properties and classification of BRDF;and the color reproduction theory based on the combination of physical BRDF and multi-spectrum.2.The studied examined the pseudo inverse algorithm,BRDF algorithm and multispectral PCA algorithm on spectral reconstruction of multispectral image.According to the experiments results,the color copied by multi spectral PCA spectral reconstruction algorithm demonstrated a better performance in color difference and spectral reconstruction accuracy(RMSE),which meet the requirements of cross media color reproduction of oil paintings.3.The study adopted color real reproduction technology based on the combination of BRDF and multispectral image to reflect the texture and material information of oil painting in cross-media color reproduction,designed a cross-media reproduction system of oil painting art,and analyzed the actual effect of color reproduction technology based on the combination of physical BRDF and multi-spectrum.In the present study,the researcher designed a BRDF and multispectral image acquisition system.Firstly,multi spectral PCA spectral reconstruction algorithm is used to reconstruct the spectral reflectance of oil painting surface,and then the image information and color information of oil painting are copied;secondly,the spatial information and color information of oil painting samples are copied by the combination of physical BRDF and multi spectral image.The experimental results show that the two methods have better performance in the part where the texture information is not obvious.However,in the part with high bright spots and highlighting the texture of oil painting,the multispectral PCA method can reproduce the image with a lower realistic sense of oil painting than the physical BRDF and multispectral method,which proves the effectiveness of BRDF in copying the texture and material information of oil painting across media. |
