Image Number 4 for United States Patent #6522779.
Representing an image includes extracting information reflecting one or more characteristics of an image that then is used to compute a first histogram vector. The first histogram vector includes one or more vector elements, each representing information for a different characteristic extracted about the image. Multiple subsets are identified within at least one of the vector elements included in the first histogram vector and a second histogram is created. The second histogram vector includes a vector element for each of the subsets identified within the vector elements included in the first histogram vector. Data within the vector elements of the second histogram vector represents the extracted image characteristics.