1. An image decoder, comprising: a pixel texture decoder configured to obtain pixel colors of pixels of a decoded image from an encoded image representation of a high dynamic range scene; and a deformatter configured to extract a region differentiator grey value from a metadata of the encoded image representation, wherein the region differentiator grey value includes a predetermined luma value for separating lumas of all pixels of a first object from lumas of all pixels of a second object in a least one block of the encoded image.