Extraction of detailed image regions for content-based image retrieval

We present a technique for coarsely extracting the regions of natural color images which contain directional detail, e.g., edges, texture, etc., which we then use for image database indexing. As a measure of color activity, we rise a perceptually modified distance measure based on the sum-of-angles criterion. We then apply histogram thresholding techniques to separate the image into smooth color regions and busy regions where edge, texture and colour activity exists. Database indices are then created from the busy regions using the direcional detail histogram technique and retrieval is performed using these.