Patent attributes
To make available a HDR image encoding mechanism with strongly improved usability, we describe an image encoding unit (301) arranged to encode a high dynamic range image (IM_HDR-in) comprising: —an LDR selector (311) for identifying a low dynamic range of luminances (R_Norml_LDR) or corresponding range of luma code values (R_LDR) within the total range of luminances (Range_HDR) covered by the high dynamic range image; —a HDR selector for selecting at least one complementary range (R_above) within the total range of luminances (Range_HDR), comprising mostly luminances not covered by the low dynamic range of luminances (R_Norml_LDR); —a code mapping unit (315) arranged to encode in a first image (Im_1*), having a luma component comprising N bit code words, pixel luminances of the high dynamic range image (IM_HDR-in) falling within the low dynamic range of luminances (R_Norml_LDR) to code values (Y_out) according to a first mapping (CMAP_L), and pixel luminances of the high dynamic range image (IM_HDR-in) falling within the at least one complementary range (R_above) to code values (Y_out) according to a second mapping (CMAP_H), wherein the first and second mappings map to disjunct subranges of the range of luma code values of the first image (RcTot_Im1).
