公开(公告)号：WO2021236070A1

公开(公告)日：2021-11-25

申请号：PCT/US2020/033655

申请日：2020-05-19

Applicant: GOOGLE LLC

Inventor： IZADI, Mohammad ,  MADHUSUDANARAO, Pavan ,  ADSUMILLI, Balineedu

IPC: G06T5/00

Abstract: Image data is processed for noise reduction before encoding and subsequent decoding. For an input image in a spatial domain, two-dimensional (2-D) wavelet coefficients at multiple levels are generated. Each level includes multiple subbands, each associated with a respective subband type in a wavelet domain. For respective levels, a flat region of a subband is identified, which flat region includes blocks of the subband having a variance no higher than a first threshold variance. A flat block set for the subband type associated with the subband is identified, which includes blocks common to respective flat regions of the subband. A second threshold variance is determined using variances of the flat block set, and is then used for thresholding at least some of the 2-D wavelet coefficients to remove noise. After thresholding, a denoised image is generated in the spatial domain using the levels.