One key component in providing effective image data management support is an expressive query language/interface. In this paper, we describe the Exquisi system that we have developed. A main contribution of Exquisi is its ability to allow a user to express subtle differences that may exist between images to be retrieved and other images that are similar. In particular, it allows the user to incorporate ambiguities and imprecisions in specifying his/her query. Another important aspect of Exquisi is the provision of a reformulation language by which the user can ask "like this in what" queries, by specifying which parts of a returned image the user wants to include and exclude.