| 摘要 |
An input HDR image may be represented using an SDR image and illumination information, for example, a single modulation value or an illumination map. Generally the single modulation value requires a lower bandwidth while the illumination map may support a higher dynamic range. Which illumination information to be used is adaptively chosen based on the dynamic range of the HDR image. For an HDR image with the dynamic range below a threshold, only the single modulation value is transmitted in the bitstream. Otherwise, a new local illumination information is formed based on a weighted sum of the modulation value and a normalized illumination map. A syntax element is used to indicate whether local illumination information is included in the bitstream. Using the syntax element and the local illumination information, the bitstream provides backward compatibility with decoders supporting different dynamic ranges. |
