These two “petal-pushing” images start with a composition of alstroemeria petals, photographed for high-key HDR on a light box.
The image with a black background (shown above) is an LAB L-channel inversion of the original image on white, shown below.
Generally, with light box compositions, the most important issue is the arrangement, a/k/a the composition. By the way, this is a statement that could be made (and has been made) about photography in general.
Can you identify the visual structure underlying the Petals on Parade images?