A survey on content-based retrieval for multimedia databases <s> Color <s> While general object recognition is difficult, it is relatively easy to capture some primitive image properties such as color distribution, prominent regions and their geometrical properties from an image and use these features to narrow down the search space when attempts to retrieving images by contents from an image database are made. The authors are building an image database in which images are indexed by both the numerical index keys generated automatically from the captured primitive image features using a set of rules, and traditional descriptive keywords entered by users when images are loaded. Users can either use the descriptive keywords or provide information regarding these image properties to query and retrieve images from the database. With this approach, the authors turn the difficult problem of image matching into image retrieval by index keys, which can be performed easily and rapidly using current database techniques. Initial experiments on the image database system show promising performance. > <s> BIB001 </s> A survey on content-based retrieval for multimedia databases <s> Color <s> The availability of large image databases is emphasizing the relevance of filters, which permit one to focus on a small subset of data. Visual specification of such filters provides a natural way to express content-oriented queries. To support a high power of expression, an original visual language is proposed for the symbolic representation of the semantics induced by the color quality and arrangement over a painting. The proposed language is based on the theory of color semantics introduced by artists in the 20th Century, and is developed to support a visual querying paradigm. This paper formalizes the grammar of the language in its visual form and describes it implementation in a prototype system of painting retrieval by color content. <s> BIB002
Images are retrieved by specifying colors and their spatial distribution in the image. This way of specification is often applied for the retrieval of paintings by principal colors with spatial relation. Examples of systems capable of processing this type of query are BIB002 ,  , BIB001 . Gong et al. BIB001 allows us to specify an example image (digitized photo) as the example of colors with spatial distribution, where a representative plane is divided into nine (3 × 3) subplanes. QBE by color is often accompanied by the specification of spatial relations of color components specified. Therefore, strictly speaking, the scheme of query specification in these studies is categorized into that of specifying the combination of spatial relation and color. In query evaluation, a color difference as well as the spatial distribution is valued in order to show the degree of satisfying specified conditions.