A HDR video decoder (600, 1100) arranged to calculate a HDR image (Im_RHDR) which has a pixel which has a luminance, based on applying to a luma (Y'_in) of a pixel of a received 100 nit standard dynamic range image (Im_RLDR) a set of luminance transformation functions, the functions comprising at least a coarse luminance mapping, which is applied by a dynamic range optimizer to the pixel luma (Y'_in) of the standard dynamic range image yielding a dynamic range adjusted luma (Y'HPS), and subsequently by a range stretcher application of a second function which is a mapping of the darkest value of the dynamic range adjusted luma (Y'HPS) onto a received black offset value (Bk_off) yielding an intermediate HDR luminance (L_HDR_IM) or luma (Y'HP); characterized in that the HDR video decoder further comprises a gain limiter (611, 1105) which is arranged to apply, as an alternative luminance calculation which is performed on the darkest HDR scene colors in parallel to the application of the set of luminance transformation functions to obtain an alternative luminance for a pixel of said darkest HDR scene colors of the HDR image (Im_RHDR), an alternate luminance transformation function to the pixel luma (Y'_in) of the standard dynamic range image which maps onto a subset of the darkest luminances of the HDR image corresponding to the darkest lumas (Y'_in) of the standard dynamic range image,wherein the gain limiter is arranged to select a minimum of as first input the intermediate HDR luminance (L_HDR_IM) or luma obtained by applying the set of luminance transformation functions, and as second input the alternate luminance transformation function of the input luma (Y'_in), wherein the HDR video decoder receives the at least a coarse luminance mapping and the black offset value (Bk_off) as metadata of the received 100 nit standard dynamic range image (Im RLDR) and wherein the alternate luminance transformation function is the inverse of the alternate luminance transformation function which was used by the encoder which created the received 100 nit standard dynamic range image. characterized in that the HDR video decoder further comprises a gain limiter (611, 1105) which is arranged to apply, as an alternative luminance calculation which is performed on the darkest HDR scene colors in parallel to the application of the set of luminance transformation functions to obtain an alternative luminance for a pixel of said darkest HDR scene colors of the HDR image (Im_RHDR), an alternate luminance transformation function to the pixel luma (Y'_in) of the standard dynamic range image which maps onto a subset of the darkest luminances of the HDR image corresponding to the darkest lumas (Y'_in) of the standard dynamic range image,wherein the gain limiter is arranged to select a minimum of as first input the intermediate HDR luminance (L_HDR_IM) or luma obtained by applying the set of luminance transformation functions, and as second input the alternate luminance transformation function of the input luma (Y'_in), wherein the HDR video decoder receives the at least a coarse luminance mapping and the black offset value (Bk_off) as metadata of the received 100 nit standard dynamic range image (Im RLDR) and wherein the alternate luminance transformation function is the inverse of the alternate luminance transformation function which was used by the encoder which created the received 100 nit standard dynamic range image.