A method comprising: receiving a standard dynamic range, SDR, image; generating composer metadata of a first level through composer metadata of an N-th level, where N is a positive integer greater than one; wherein composer metadata of an i-th level in the composer metadata of the first level through the composer metadata of the N-th level is generated concurrently or sequentially with composer metadata of a j-th level in the composer metadata of the first level through the composer metadata of the N-th level, where 1 <= i < j <= N, and wherein the composer metadata of the j-th level is generated dependent and based on the composer metadata of the first level through composer metadata of (j-1)-th level, where i and j are positive integers; wherein the composer metadata of the first level through the composer metadata of the i-th level in the composer metadata of the first level through the composer metadata of the N-th level is to be used for mapping the SDR image to an i-th target image specifically optimized for the i-th reference target display in N different reference target displays having different target dynamic ranges; wherein the composer metadata of the first level through the composer metadata of the j-th level in the composer metadata of the first level through the composer metadata of the N-th level is to be used for mapping the SDR image to a j-th target image specifically optimized for the j-th reference target display in the N different reference target displays; encoding the SDR image and the composer metadata of the first level through composer metadata of a k-th level in the composer metadata of the first level through the composer metadata of the N-th level in an output SDR video signal, where 1 <= k <= N, where k is a positive integer, wherein the composer metadata of the first level through the composer metadata of the k-th level is progressively encoded from the first level to the k-th level; causing a display device operating with a receiver of the output SDR video signal to render a display image, wherein the display image is derived from a composed target image composed from the SDR image based on the composer metadata of the first level through the composer metadata of the k-th level in the output SDR video signal. receiving a standard dynamic range, SDR, image; generating composer metadata of a first level through composer metadata of an N-th level, where N is a positive integer greater than one; wherein composer metadata of an i-th level in the composer metadata of the first level through the composer metadata of the N-th level is generated concurrently or sequentially with composer metadata of a j-th level in the composer metadata of the first level through the composer metadata of the N-th level, where 1 <= i < j <= N, and wherein the composer metadata of the j-th level is generated dependent and based on the composer metadata of the first level through composer metadata of (j-1)-th level, where i and j are positive integers; wherein the composer metadata of the first level through the composer metadata of the i-th level in the composer metadata of the first level through the composer metadata of the N-th level is to be used for mapping the SDR image to an i-th target image specifically optimized for the i-th reference target display in N different reference target displays having different target dynamic ranges; wherein the composer metadata of the first level through the composer metadata of the j-th level in the composer metadata of the first level through the composer metadata of the N-th level is to be used for mapping the SDR image to a j-th target image specifically optimized for the j-th reference target display in the N different reference target displays; encoding the SDR image and the composer metadata of the first level through composer metadata of a k-th level in the composer metadata of the first level through the composer metadata of the N-th level in an output SDR video signal, where 1 <= k <= N, where k is a positive integer, wherein the composer metadata of the first level through the composer metadata of the k-th level is progressively encoded from the first level to the k-th level; causing a display device operating with a receiver of the output SDR video signal to render a display image, wherein the display image is derived from a composed target image composed from the SDR image based on the composer metadata of the first level through the composer metadata of the k-th level in the output SDR video signal.