Back-lit transmissive display having variable index light extraction layer

A back-lit transmissive display assembly, comprising:

• a transmissive display;
• and
• an illumination article comprising a lightguide and a variable index light extraction layer, the variable index light extraction layer optically coupled to the lightguide and the transmissive display, the variable index light extraction layer having first and second regions, the first region comprising nanovoided polymeric material, the second region comprising the nanovoided polymeric material and an additional material disposed within the nanovoided polymeric material, the first region having a first refractive index, the second region having a second refractive index, the additional material increasing the second refractive index over the first refractive index by at least about 0.03, the first and second regions being disposed such that for light emitted by a light source and injected into the lightguide, the variable index light extraction layer selectively extracts the light in a predetermined way based on the geometric arrangement of the first and second regions, wherein the nanovoided polymeric material comprises a plurality of interconnected nanovoids.