To improve the discrimination power of color-indexing techniques, we e
ncode a minimal amount of spatial information in the index, We tessela
te each image with five partially overlapping, fuzzy regions, In the i
ndex. for each region in an image, we store its average color and the
covariance matrix of the color distribution. A similiarity function of
these color features is used to match query images with images in the
database. In addition, we propose two measures to evaluate the perfor
mance of image-indexing techniques. We present experimental results us
ing an image database which contains more than 11,600 color images.