This paper suggests a discriminative approach for wavelet denoising
where a set of mapping functions (MF) are applied to the transform
coefficients in an attempt to produce a noise free image. As opposed
to the descriptive approaches, modeling image or noise priors is not
required here and the MFs are learned directly from an ensemble of
example images using least-squares (LS) fitting. Using the suggested
scheme, a novel set of MFs are generated that are essentially
different from the traditional soft/hard thresholding in the
over-complete case. These MFs are demonstrated to obtain comparable
performance to the state-of-the-art denoising approaches. This
framework enables a seamless customization of the shrinkage
operation to a new set of restoration problems that previously were
not addressable with shrinkage techniques, such as: de-blurring,
JPEG artifact removal, and various types of additive noise that are
not necessarily Gaussian white noise.