US Patent 10027965 HDR image encoding and decoding methods and devices

To have a very efficient and in some embodiments also backwards compatible with legacy LDR display systems, apparatuses and methods relating to decoding an image encoding (LDR_CONT) corresponding to a first luminance dynamic range (R_oLDR) into a second luminance dynamic range (R_oHDR) output image (HDR_FIN), in which image encoding (LDR_CONT) are encoded pixels of an original image (HDR_ORIG) of a high dynamic range scene, the method comprising:tone mapping with a predetermined tone mapping strategy (FL2H) at least the lumas of pixels in the image encoding (LDR_CONT) onto lumas of pixels in an intermediate image (HDR_PRED) corresponding to the second luminance dynamic range (R_oHDR); andmodifying the lumas of at least some of the pixels of the intermediate image (HDR_PRED) by multiplying them with predetermined multiplication factors, resulting in the output image (HDR_FIN) are taught.