Heitou Zen

Moving object detection from MPEG coded picture

Intelligent transport systems (ITS) have been developed as next generation systems which unite multimedia technology and the roadway. One ITS technology, image processing, for example, the detection and tracking of moving objects (e.g. vehicles), is studied. On the other hand, the coding technique of MPEG (Motion Picture Experts Group) is used as the worldwide standard method of video data compression. Japan Highway Public Corporation (JH) adopted MPEG to transmit picture data from the surveillance system on the roadway to the control center. Therefore, we propose a method to analyze moving pictures by directly manipulating the MPEG stream. Our proposed method extracts plural moving objects from the MPEG stream without a decoding process, and tracks them even if they approach and cross. It is implemented to extract moving cars on the roadway, and its effectiveness is verified.

A color video image quantization method with stable and efficient color selection capability

Color video images have become a very important media in communication. This has increased the necessity of displaying and handling color video images on various types of computers. In computerized color image processing, most color images are represented by 24 bits per pixel. Such images usually contain a lot of redundancy and require a large amount of space to be stored. Furthermore, they require expensive full color display devices, so that many general-purpose computers which have only colormap display devices are not capable of displaying them. In order to lower the display and the storage cost, color image quantization algorithms are needed to reduce the number of colors in original images. The authors propose a color quantization method for video images which efficiently generates color quantized video images with stable color allocations.<<ETX>>

A Color Moving Image Quantization Method with Stable and Efficient Color Selection Capability.

In this paper, we propose a color quantization method for moving images which efficiently composes color quantized moving images with stable colors. In this method, the initial set of colors is chosen from the first frame, and used with high priority for the rest of the image sequence to achieve stable color allocation. To use the high correlation between subsequent frames, the color difference of each corresponding pixel between subsequent frames is first calculated and compared with the appropriate threshold. Then the pixels whose color differences are under the threshold are allocated to the same colors of the corresponding pixels of the preceding frame, and the colors of other pixels are reallocated. By this method, only differential operation is employed for most pixels.This method can also detect scene changes by monitoring the content of the “LUT”, so that it can deal with various kinds of moving images.Several experimental results in which the images of 224 colors are quantized to 16 colors reveal the effectiveness of the proposed method.