Iterative soft color-shrinkage for color-image denoising

To remove signal-dependent noise of a digital color camera, we present a new soft color-shrinkage scheme for color-image denoising in a wavelet transform domain. The classic soft-shrinkage scheme works well for monochrome-image denoising; to utilize inter-channel color cross-correlations, a noisy image undergoes the color-transformation from the RGB to the luminance-and-chrominance color space, and the luminance and the chrominance components are separately denoised. However, this color-denoising approach cannot cope with actual signal-dependent noise. To utilize the noise´s signal-dependencies, we present an iterative soft color-shrinkage scheme where the inter-channel color cross-correlations are directly utilized in the RGB color space, and theoretically study its convergence property. Our color-shrinkage scheme alleviates denoising artifacts, and improves picture quality of denoised images.