In Content-Based Image Retrieval (CBIR) two querymethods exist: query-by-example and query-by-memory. The user either selects an example image or selects image features retrieved from memory (such as color, texture, spatial attributes, and shape) to define his query. Hitherto, research on CBIR interfaces was absent. Hence, a usability evaluation of existing (CBIR) interfaces was done. Additionally, a study concerning human color cognition was conducted. Based on the resulting findings, a prototype color selection interface was developed. In a theoretical experiment, using Fitts' law, was proven that the prototype interface is highly efficient for CBIR purposes. This all resulted in a first set of design guidelines for CBIR color selection interfaces.