An apparatus for combining two images or two videos of images (Im_HDR, Im_LDR) from different sources and with different maximum luminance, one of them being a high dynamic range image or video, the apparatus comprising: - a dynamic range establishing unit arranged to establish a combination luminance dynamic range (CombRng), being characterized by at least a maximum luminance which is determined based on the maximum luminances of the two images or the two videos of images, the dynamic range establishing unit further comprising a luminance anchor determining unit, arranged to determine an anchor luminance (anc) in the combination luminance dynamic range (CombRng); - a color transformation unit, arranged to perform at least a luminance transformation on at least one of the two images or videos, wherein the color transformation unit comprises a source anchor luminance reading unit arranged to read at least one source anchor luminance (L_SA1) from metadata from a first source which delivers a first image or video (Im1_LDR) of the two images or videos, and wherein the color transformation unit is arranged to establish a luminance transformation (FF_1) to be applied to the first image or video yielding a first output image having first output luminances, which luminance transformation is dependent on the value of the source anchor luminance (L_SA1) by having the property that the source anchor luminance (L_SA1) is mapped to an output luminance in a vicinity of the anchor luminance (anc); and - an image combination unit arranged to combine the output luminances of the first output image with luminances of the other one of the two images or two videos of images to form at least one combined output image (Im_o). - a dynamic range establishing unit arranged to establish a combination luminance dynamic range (CombRng), being characterized by at least a maximum luminance which is determined based on the maximum luminances of the two images or the two videos of images, the dynamic range establishing unit further comprising a luminance anchor determining unit, arranged to determine an anchor luminance (anc) in the combination luminance dynamic range (CombRng); - a color transformation unit, arranged to perform at least a luminance transformation on at least one of the two images or videos, wherein the color transformation unit comprises a source anchor luminance reading unit arranged to read at least one source anchor luminance (L_SA1) from metadata from a first source which delivers a first image or video (Im1_LDR) of the two images or videos, and wherein the color transformation unit is arranged to establish a luminance transformation (FF_1) to be applied to the first image or video yielding a first output image having first output luminances, which luminance transformation is dependent on the value of the source anchor luminance (L_SA1) by having the property that the source anchor luminance (L_SA1) is mapped to an output luminance in a vicinity of the anchor luminance (anc); and - an image combination unit arranged to combine the output luminances of the first output image with luminances of the other one of the two images or two videos of images to form at least one combined output image (Im_o).