The process of planning interior lighting is not generally systematic. This research is specifically aimed at developing a software catalogue to aid this task, and more generally to develop guidelines for system interfaces involving complex operations with ill-defined objectives. Interviews with lighting planner showed that clients do not generally have a clear requirement in mind, and the job is generally entrusted to the planner's knowledge. This software provides a systematic and interactive light planning too1 using an image searching algorithm based on rough set theory, and allows composition of the selected light in a variety of interior settings.