METHOD AND DEVICE FOR ENCODING A HIGH-DYNAMIC RANGE IMAGE

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.