LightTools version 3.1 from Optical Research Associates can model a variety of textured surfaces such as paint dots, masks, appliques and arrays of thin lenses. Complex, nonperiodic images can be described using a monochromatic bit-map image. Chromaticity information such as CIE color coordinates and correlated color temperature can be computed. A ray-tracing feature allows the software to choose which rays to trace, ignoring ray paths that carry less power. Continuous spectral-distribution functions for light sources have been added to enhance source modeling capabilities.