Research On Content-based Image Retrieval Technology

With the development of network and multimedia technology, image resources become more and more abundant, the traditional method which based on text keyword is unable to fulfill the demand of image retrieval. Content-Based Image Retrieval which becomes one of the hottest research topics in the field of image has emerged at the right moment. This paper mainly investigated the methods of image retrieval which based on color and shape.Firstly, a general overview of the development and research actualities of the content-based image retrieval system are introduced, and its key technology is researched, including the extraction of the image features (such as color, texture, shape and spatial relationship), the similarity measurement, relative feedback and retrieval performance evaluation.Secondly, as for the extraction of the shape feature, an image retrieval algorithm (ISE) is proposed based on modified moment invariant features, in the algorithm, eccentricity is joined in the seven traditional Hu moment invariants. Experimental data show that image retrieval based on ISE algorithm has some advantages of translation, rotation, scaling and distortion invariance of image, and has good affect in maintaining the consistency of the shape, and especially has good retrieval results to the target specific images.Thirdly, as for the color feature extraction, because of the loss of space information of global color histogram, image is divided into small pieces, HSV color space is chosen and the color is quantized to 72-dimensions. Color histogram of each partition is counted, and the color which contains the largest number of pixels is dominant color of the partition. The implementation of image retrieval is through counting similarity distance which is the cumulative distance of the corresponding blocks between the sample image and database images.Finally, in order to design and implement the content-based image retrieval prototype system by synthesizing the feature of dominant color of the partition and modified shape invariant moment, the image retrieval method integrated with color and shape features are researched. The system can retrieval images based on single feature or color and shape features. The experimental results show that image retrieval based on invariant moment has better retrieval efficiency while the image has specific targets or the user want to retrieval images which include translation, rotation, scaling or distortion targets. According to the characteristics of the image, users can retrieval images by giving different ratio to the two features. The retrieval precision of fusion multi-feature is much higher than traditional single feature retrieval.