Systems and methods of denoising images are described. In one aspect,
spatially-shifted forward transforms of the input image are computed.
Each forward transform is computed based on a denoiser transform Z having
an associated transpose Z', wherein a matrix multiplication between Z and
Z' produces a diagonal matrix .LAMBDA., Z=F(D), F specifies a mapping
from coefficients of D to coefficients of Z, and D substantially
corresponds to a frequency-domain transform. The forward transforms are
denoised based on nonlinear mappings derived from quantization values
linked to the input image. Spatially-shifted inverse transforms of the
denoised forward transforms are computed. Each inverse transform is
computed based on Z and Z'. An output image is computed based on a
combination of spatially-shifted inverse transforms.