公开(公告)号：EP3085088A1

公开(公告)日：2016-10-26

申请号：EP14820807.7

申请日：2014-12-15

申请人： Thomson Licensing

发明人： LASSERE, Sebastien ,  LELEANNEC, Fabrice ,  TOUZE, David

IPC分类号： H04N19/124 ,  H04N19/154 ,  H04N19/164 ,  H04N19/33 ,  H04N19/36

摘要： The present invention generally relates to a method and device for encoding an image block by means of a block-based spatial-to-frequency transform. The method is characterized in that it comprises: - obtaining (100) a luminance component of the image block; - obtaining (101) a low-spatial-frequency version ( L lf ) of the luminance component of the image block; - quantifying (102) the low-spatial-frequency version ( L lf ) of the luminance component of the image block; - obtaining (103) a differential luminance component ( L r ) by calculating the difference between the luminance component (L) of the image block and a version L l �¢ f , Q �¢ L l �¢ f , Q ^ of the low-spatial-frequency version of the luminance component of the image block; - encoding (104) the quantified low-spatial-frequency version ( L lf,Q ) of the luminance component of the image block on at least one frequency coefficient (DC) of a set of frequency coefficients obtained from the block-based spatial-to-frequency transform for encoding the luminance component of the image block; and - encoding (105) the differential luminance component ( L r ) on the remaining frequency coefficients (AC) of said set of frequency coefficients. The invention relates also to a method and device for decoding a bitstream representing a luminance component and potentially at least one transformed colour component of an image block. Is further relates to a method and device for encoding an image and for decoding a bitstream representing an image.