This paper proposes a novel wavelet domain based noise reduction scheme that is based on decorrelation of the spatio-temporal filter for video denoising that exploits the tem-temporal data, followed by adaptive thresholding. The discrete poral as well as spatial correlations which exist in the subband cosine transform (DCT) is used for temporal decorrelation representation of the video sequence. The temporal redundancy cne is usedtfor tmoral decorrlion or correlation among the corresponding wavelet coefficients inn the next section along with the outline of neighboring frames is minimized by the use of discrete cosine the algorithm. Section III describes the hierarchically adapted transform. These decorrelated noisy wavelet coefficients are thresholding scheme for spatial noise reduction. Experimental then denoised spatially via a low-complexity wavelet shrinkage results are provided in Section IV, followed by the conclusions method, which utilizes the correlation that exists between sub-in Section V. sequent resolution levels. The proposed scheme shows promising results and outperforms state-of-the-art spatio-temporal filters II TEMPORAL DECORRELATION USING DCT in time as well as wavelet domains, both in terms of PSNR and visual quality.Consider a noise-free video sequence whose nth frame can be represented as f'. Each of the noise-free frames in the original video sequence is corrupted with a set of zero-mean Digital video, which can be considered as a sequence of AWGN, q', having a variance or2, so as to yield the observed images or frames, has become vastly popular during the last frames of the noisy video sequence: decade. The corruption of such sequences by noise is also a common phenomenon, which hinders further processing of the g F +
91(1) video or its compression. Most of the existing techniques for This work is concerned with obtaining an estimate, f1, of the the removal of additive white Gaussian noise (AWGN) (e.g., noise-free frame, fn, given the observed noisy frame, gn.[1-4]) consider the video as spatio-temporal data and extendThe input noisy frame is transformed to the wavelet domain ID or 2D filters to exploit the spatial as well as temporal using the critically-sampled discrete wavelet transform (DWT) redundancies that exist in a video sequence. However, most and owing to the linearity and orthogonality of the wavelet of these schemes fail to reduce noise sufficiently.transform, the corrupting noise in the wavelet domain is also More recently, following the success of wavelets for noise additive: removal in still images, wavelet based video noise reduction yn = xn + nschemes have been proposed in [5,6].[5] uses the wavelet domain for spatial denoising only and exploits the temporal where yn and Xn are the sets of noisy and noise-free wavelet redundancy in the time domain using weighted averaging. On coefficients and n is the set of corrupting zero-mean AWGN the other hand, [6] employs weighted averaging over a spatio-coefficients having a variance r2. temporal window in the wavelet domain to...