In one embodiment, a method of defining an array of extractor elements configured to extract light from a light guide, and thereby produce a desired spatial light pattern E.sub.T quantifying optical output at a plurality of locations across the light guide is provided. The method comprises calculating a first spatial light pattern produced by a first array of extractor elements. The first spatial light pattern quantifies optical output at the plurality of locations across the light guide. The method further comprises determining a ratio R of the optical output of the desired spatial light pattern to an optical output of the first spatial light pattern. The method further comprises determining a modified ratio R', wherein R'=R.sup..alpha. and |.alpha.|<1. The method further comprises determining a characteristic of a second array of extractor elements by scaling a characteristic of the first array of extractor elements by the modified ratio R'.