This is an example of the role of spatiality - the negative space has created its own shape. I would also argue that this ad is contrasting the image of white legs against the vast black background to emphasize the importance of that image - it is a dramatic statement that would be less dramatic if there was some other element in the ad to detract from the message. http://www.gomediazine.com/tutorials/rule-three-contrast-contrast-contrast/
Value Contrast – by imogenl on Polyvore.com The pic here is in neutral colours, but works for any combination of colours and also patterns. Quite often I find that some of the clothes that my clients have that they rarely or never wear, is either too high or low contrast for their colouring, so they never feel comfortable or think they look great in it.