Research in image retrieval attracts researchers and practitioners from a variety of fields, and one major research challenge is meeting the needs of the end users of those images (Jorgensen, 2003). Jorgensen (2003) also suggests that various image collections are needed for system evaluation and that to "ensure both reliability and validity of testing results, the content should be grounded in the reality of the image community who make heavy use of digital images in their jobs, as well as providing suitable testing material for a variety of techniques" (p. 267).