Restoration of high ISO-sensitivity color images

Recently, R. H. Chan, et al. proposed an image restoration method with the shift-invariant Haar wavelet transform. The method is suitable for image restoration in a digital color camera, but in a heavily noisy case produces artifacts originating from noise. In such a case, the restoration process should be split into three stages: color-interpolation, denoising, and deblurring; and along this line we present an approach to restore a high ISO-sensitivity image. Our approach firstly demosaics observed color data with the bilinear interpolation, which is robust against noise but causes blurs. Next, it applies our previously proposed color-shrinkage to each wavelet coefficient or each grouplet coefficient of the demosaicked image, to produce a denoised one. Finally, it applies to the denoised image a color-image restoration method corresponding to an extension of the method of Chan et al., and employs our previously proposed soft color-shrinkage. Our approach restores a high-quality image even in an ISO-6400 case.