To allowed for increased security for selling HDR movies (or at least HDR experiences) even when some of the movie data gets pirated, an image transformation apparatus (201) is arranged to derive a e.g. a high dynamic range image (HDR_PRED) from a low dynamic range image (LDR_CONT) or any dynamic range image (e.g. a display driving image) from any dynamic range input image, wherein the derivation comprises tone mapping of lumas of pixels in the low dynamic range image into lumas of pixels of the high dynamic range image by applying at least one predefined mapping algorithm (gam), the image transformation apparatus comprising: -an input (204) to a data delivery system (205) comprising the low dynamic range image; -a data-secured input (206) to the at least one predefined mapping algorithm (gam) data; and -a control unit (202) arranged to manage access to the predefined mapping algorithm data under control of an owner of artistic content in the low dynamic range image, which allows for better control of the authorized regularity of the content when it is to be rendered, which is possible because of our special HDR image encoding strategy.