Good news (I think)

The Independent offers some reassurance to those worried about the size of their posteriors:

Does wearing black make your bum look smaller?

Yes. The human eye can only perceive shapes if the object appears in different shades or colours. It is easier to notice wrinkles on a piece of light clothing than on a dark one. Thus in black clothing the shadows are barely discernible and the shape appears flat. The problem is that this only works when viewing directly from behind. When in profile, the backside will still reveal its true dimensions. The effect of shadows on the human face also explains why people of a darker complexion appear to age better than those with pale skin. Wrinkles are visible by the shadows they create and are therefore harder to see on dark skin.