基于多阶段优化的壁画图像色彩还原

Mural Color Restoration via Multi-Stage Optimization

敦煌壁画是中国最有价值和不可再生的文化遗产之一。而壁画图像的色彩复原对敦煌壁画的数字化保护和展示具有重要意义。为了解决褪色壁画图像色彩还原过程中出现的边缘伪影和色彩混叠问题,提出一种基于多阶段优化的壁画图像色彩还原方法。该方法利用高斯核函数得到壁画图像的多尺度表示。同时,构建三个基于编码器-解码器的迁移子网来学习壁画图像多尺度表示的语义特征,在参考壁画和褪色壁画之间建立语义关联来恢复壁画颜色。采用由粗到细的优化策略,在各个阶段间构建跨尺度特征融合模块实现图像多尺度表示的特征融合,建立不同阶段间的特征依赖关系。通过多阶段逐步优化,实现壁画图像的色彩还原。通过对临摹壁画和真实壁画的实验表明,该方法能够较有效地消除噪声影响,在还原壁画色彩的同时能较好地保持褪变色壁画图像的边缘纹理信息。

Dunhuang murals are one of the most valuable and non-renewable heritages of China.The color restoration of mural images is very important for the digital protection and display of Dunhuang murals.This paper proposes a color res-toration method based on multi-stage optimization in order to solve the problems of edge artifacts and color aliasing in faded mural restoration.The method obtains the multi-scale representation of the mural image using the Gaussian kernel function.Meanwhile,three encoder-decoder based transfer subnets are constructed to learn the semantic features of multi-scale representation of mural images.The transfer subnet establishes the semantic association between reference mural and faded mural to restore the mural’s color.The proposed multi-stage model adopts a coarse-to-fine optimization strategy.The cross-scale feature fusion module is constructed to realize the feature fusion of image multi-scale representation and establish the interdependency between different stages.Mural color restoration is realized through the gradual optimiza-tion of the multi-stage model.The experiments based on copying and real murals demonstrate that the proposed method can effectively eliminate the effect of noise and keep the texture information of the fading mural image while restoring the color of the mural image.