An illumination apparatus comprises: (a) at least one light source; (b) a light guide for accepting light from the at least one light source and for guiding the light using total internal reflection, the light guide having a top surface; (c) a light extracting film having an input surface optically coupled with the top surface and an output surface for providing light, wherein the input surface comprises a plurality of features which are optically coupled to the top surface of the light guide, such features having: (i) a first side comprising two or more planar segments; and (ii) a second side comprising two or more planar segments, and wherein either the length of at least some of the features is less than the width of the film or the first and second sides intersect at an apex.