The convergence and stability of the level set method depend on the speed function. Therefore, it is important to define the speed function in a manner that is suitable for the individual application. In the present paper, we propose a novel speed function of the level set method for moving object extraction from a video sequence with a stationary background. The speed function focuses on the precision of moving object extraction. In the proposed extraction method, the outline between moving object regions and the background is estimated in advance based on the Gaussian noise distribution in the frame. The speed function is changed adaptively using the obtained outline in order to improve the convergence and precision of extraction. In addition, a new energy term in the direction of the contour of an object is incorporated into the speed function. The precision of the moving object extraction method using the proposed speed function is evaluated through computer simulations.

The present paper proposes an automatic extraction technique of moving objects using x-means clustering. The proposed technique is an extended k-means clustering and can determine the optimal number of clusters based on the Bayesian Information Criterion(BIC). In the proposed method, the feature points are extracted from a current frame, and x-means clustering classifies the feature points based on their estimated affine motion parameters. A label is assigned to the segmented region, which is obtained by morphological watershed, by voting for the feature point cluster in each region. The labeling result represents the moving object extraction. Experimental results reveal that the proposed method provides extraction results with the suitable object number.

MPEG-4, which is a video coding standard, supports object-based functionalities for high efficiency coding. MPEG-7, a multimedia content description interface, handles the object data in, for example, retrieval and/or editing systems. Therefore, extraction of semantic video objects is an indispensable tool that benefits these newly developed schemes. In the present paper, we propose a technique that extracts the shape of moving objects by combining snakes and watershed algorithm. The proposed method comprises two steps. In the first step, snakes extract contours of moving objects as a result of the minimization of an energy function. In the second step, the conditional watershed algorithm extracts contours from a topographical surface including a new function term. This function term is introduced to improve the estimated contours considering boundaries of moving objects obtained by snakes. The efficiency of the proposed approach in moving object extraction is demonstrated through computer simulations.

A high-efficiency video coding method using matching pursuits, which is a waveform coding technique, has recently been proposed. In this method, the motion compensated prediction error image is encoded by applying matching pursuits. In the present paper, we propose a matching pursuits coding method that encodes the sub-band images derived from motion compensated prediction error images. The complexity of the proposed method is reduced compared to the full-band matching pursuits because of lighter inner product computation due to reduction of both the resolution of the sub-band and the basis function length of the dictionary. We evaluated the coding performance and computational complexity of the proposed method via computer simulations

In this paper, we propose two fast encoding algorithms for vector quantization. The first algorithm uses three significant features of a vector, that is , the norm, its projection angle to a reference line and the mean, to reduce the search area and accelerate the search process. The second algorithm has feature of using a suitable hyperplane to partition the codebook and image data. These algorithms allow significant acceleration in the encoding process. Experimental results are presented on image block data. These results confirm the effectiveness of our proposed algorithms.

We propose a fast codebook generation algorithm for entropy-constrained vector quantization (ECVQ). The algorithm uses the angular constraint and employs a suitable hyperplane to partition the codebook and image data in order to reduce the search area and accelerate the search process in the codebook design. This algorithm allows significant acceleration in the codebook design process. Experimental results are presented on image block data. These results show that our new algorithm performs better than the previously known methods.

A new digital method for separation and reconstruction of NTSC color TV signals is described. Digital conversion between an NTSC signal and its baseband component signals is performed at a sampling rate of(12/5)f_{sc} \simeq 8.59MHz (fsc: the color subcarrier frequency), which is lower than the conventionally used3f_{sc}or4f_{sc}sampling rate. Since this lowered sampling rate satisfies the Nyquist condition for NTSC signals, the proposed digital method can provide an effective technique for the component coding of NTSC signals. Simulation results have shown that, with this method, no visible picture quality degradations can be observed for either the color bar signal or SMPTE Pictures.

An interframe coding system is described which is capable of transmitting both 4-MHz videotelephone signals and NTSC color TV signals at an average rate of 6.312 Mbits/s. The coding system takes as much advantage as possible of in-frame correlation, in addition to interframe correlation, by coding pel-to-pel difference of interframe difference (combinational difference). Variable-length word coding is effectively used to reduce the number of bits to be transmitted. In order to prevent buffer overflow, luminance and spatial resolutions are controlled. To control luminance resolution, interframe difference is multiplied by a coefficient\alpha \leq 1, so that value approaches zero when violent motion causes the buffer to fill. Though multiplication with small α results in temporal resolution reduction in moving areas, quality degradation is not too marked. Spatial resolution control is achieved by using subsample and subline coding modes.