The application of the mean shift algorithm to color image segmentation has been proposed in 1997 by Comaniciu and Meer. We apply the mean shift color segmentation to image sequences, as the first step of a moving object segmentation algorithm. Previous work has shown that it is well suited for this task, because it provides better temporal stability of the segmentation result than other approaches. The drawback is higher computational cost. For speed up of processing on image sequences we exploit the fact that subsequent frames are similar and use the cluster centers of previous frames as initial estimates, which also enhances spatial segmentation continuity. In contrast to other implementations we use the originally proposed CIE LUV color space to ensure high quality segmentation results. We show that moderate quantization of the input data before conversion to CIE LUV has little influence on the segmentation quality but results in significant speed up. We also propose changes in the post-processing step to increase the temporal stability of border pixels. We perform objective evaluation of the segmentation results to compare the original algorithm with our modified version. We show that our optimized algorithm reduces processing time and increases the temporal stability of the segmentation.
We propose a search & retrieval (S&R) tool, which supports the combination of a text search with content-based search for video and image content. This S&R system allows the formulation of complex queries allowing the arbitrary combination of content-based and text-based query elements with logical operators. The system will be implemented as a client/server system. The entire S&R system is designed in such a way that the client system can be either a web application accessing the server over the Internet or a native client with local access to the server. The S&R tool is embedded into a system called MECiTV - Media Collaboration for iTV. Within MECiTV a complete authoring environment for iTV content will be developed. The proposed S&R tool will enable iTV authors and content producers to efficiently search for already existing material in order to reduce costs for iTV productions.