Patent Document ID: 9066070
Application ID: 14113939
Patent Flag: 1

Claim One:
1. A method for the coding of High Dynamic Range (HDR) images, the method comprising: accessing an input HDR image and an input Standard Dynamic Range (SDR) image, wherein the input HDR and SDR images represent the same scene but at a different dynamic range; generating a predicted HDR image based on the input SDR image and the input HDR image; generating a residual HDR input image based on the input HDR image and the predicted HDR image; for limiting the dynamic range of the residual HDR input image, applying a non-linear quantization to the residual HDR input image to output a quantized residual image; and coding the quantized residual image using a residual encoder, wherein said residual HDR input image has a bit-depth that is higher than the bit-depth supported by the residual encoder, wherein the method step of non-linear quantization comprises: transforming pixel values of the residual HDR input image to corresponding quantized pixel values according to a non-linear transfer function; said transfer function characterized by one or more function parameters, said function parameters comprising an offset parameter and an output dynamic range parameter representative for a desired maximum dynamic range of the non-linear quantization; wherein said transfer function has a mid-range slope controlled by one or more of the function parameters, and wherein said parameters of the non-linear transfer function are set by a method comprising: receiving from the residual encoder quantizer information related to one or more of the function parameters, the offset parameter, and the output dynamic range parameter; and adjusting said one or more parameters based on said received quantizer information, wherein the non-linear transfer function comprises computing c ⁡ ( x ) = O + L max ⁢  x  x max ⁢ σ +  x  ⁢ sign ⁢ ⁢ ( x ) , wherein O denotes the offset parameter, L max denotes the output, dynamic range parameter, x is a residual HDR input pixel value, c(x) is the quantized output value, x max is the maximum absolute value of the residual HDR input pixel values, and σdenotes a function parameter controlling the mid-range slope.