Tsuyoshi Takebe

Analysis and synthesis of facial image sequences in model-based image coding

This paper proposes new methods for analyzing image sequences and updating textures of the three-dimensional (3-D) facial model. It also describes a method for synthesizing various facial expressions. These three methods are the key technologies for the model-based image coding system. The input image analysis technique directly and robustly estimates the 3-D head motions and the facial expressions without any two-dimensional (2-D) entity correspondences. This technique resolves the 2-D correspondence mismatch errors and provides quality reproduction of the original images by fully incorporating the synthesis rules. To verify the analysis algorithm, the paper performs quantitative and subjective evaluations. It presents two methods for updating the texture of the facial model to improve the quality of the synthesized images. The first method focuses on the facial parts with large change of brightness according to the various facial expressions for reducing the transmission bit rates. The second method focuses on all changes of brightness caused by the 3-D head motions as well as the facial expressions. The transmission bit rates are estimated according to the update methods. For synthesizing the output images, it describes rules that simulate the facial muscular actions because the muscles cause the facial expressions. These rules more easily synthesize the high-quality facial images that represent the various facial expressions. >

A system of analyzing and synthesizing facial images

A system is presented which analyzes and synthesizes the facial images. This system is focused on analysis and synthesis of facial features. Any particular image is assumed to be a weighted sum of facial image bases. The weights represent the facial features of the particular image. A method which analyzes and synthesizes the facial images on the basis of a three-dimensional facial shape model is presented. The method is extended so that the features of parts as well as the whole of the face can be analyzed and synthesized. Moreover, a procedure is developed for orthogonalizing the image bases for optimal description.<<ETX>>

A technique to truncate IIR filter impulse response and its application to real-time implementation of linear-phase IIR filters

A technique for realizing linear-phase infinite impulse response (IIR) filters has been proposed by Powell and Chau (1991) and gives a real-time implementation of H(z/sup -1/)/spl middot/H(z), where H(z) is a causal IIR filter function. In their system, the input signal is divided into L-sample sections, time-reversed, section convolved with H(z), and time-reversed again. The signal is then filtered by H(z) to give the system output with a processing delay of 3L+1 samples. However, the group delay response of the system exhibits a minor sinusoidal variation superimposed on some constant value. This variation will degrade image quality in image processing and signal quality in signal transmission applications. Furthermore, the output of the system contains harmonic distortion for a sinusoidal input. The main drawbacks of Powell and Chaus technique are the large processing delay of 3L+1 samples and the accompanying phase and harmonic distortions. A smaller processing delay increases the phase and harmonic distortions, yet the amplitude response remains acceptable. Previously, the present authors presented a method of reducing the processing delay by shortening the section length by an integer factor N using a structure with increased number of paths for the time-reversed signal. The authors consider how to reduce the phase and harmonic distortions. We examined the operation of the sectioned convolution and analyzed it based on a state-space representation. Then, we found that the cause of the distortions is a periodic variation of the impulse response length in the sectioned convolution. To overcome this problem, a technique is devised to realize a recursive circuit having a truncated impulse response with a fixed-length L. A system applying this technique to the Powell-Chau system is demonstrated to exhibit perfect linear-phase characteristic and produce virtually no harmonic distortion. Therefore, the section length L can be reduced without limitation due to phase and harmonic distortions. Two methods for reducing the increased computational complexity of this technique assuming fixed L are developed, and simulations are performed for the proposed system to confirm the expected improvements.

High frequency switched capacitor FIR filters using parallel cyclic type circuits

A novel transversal FIR switched capacitor circuit, called the parallel cyclic type, for high-frequency with low power consumption is presented. The circuit is constructed with several sublocks without an operational amplifier in parallel and a summing operational amplifier, in which a single active subblock moves from one subblock to another cyclically. The circuit has a significantly improved high-frequency performance. Consideration is given to the reduction of the number of capacitors and extension of the filter operating frequency range to a higher frequency. Experimental results are given.<<ETX>>

Analysis of facial expressions using a three-dimensional facial model

This paper proposes a method which analyzes an expression from a facial image using a three-dimensional facial model and then extracts the facial expression. First, the head motion and the facial actions (such as those of eyebrows, eyes, and lips) are separated from the facial image. This is realized by estimating the three-dimensional motion of the face based on the three-dimensional facial model and by compensating the motion. Next, the expression information is extracted from the separated facial actions in two ways. One is the method to extract successively the facial expressions considering the characteristics of the facial actions based on the facial muscles. The other is the method to estimate the facial expression as a whole using the least-square method and regarding the facial actions by the facial muscles as a vector. Those methods are combined with the expression synthesis rules. This makes it possible to reconstruct the original expression from the extracted facial expression parameters. Finally, the result of the analysis of the facial expression from the actual image is compared to the result of evaluation by a psychologist to demonstrate the usefulness of the proposed method. The image reconstructed from the result of analysis also is compared with the original image.

SC FIR interpolation filters using parallel cyclic networks

This paper presents a high frequency switched-capacitor FIR interpolation filter. The circuit has a multi-stage polyphase structure whose component blocks are realized by parallel cyclic networks. Design example of a partial response filter (class IV) is also included.<<ETX>>

An implementation of high-speed adaptive noise canceller with parallel block structure

An adaptive algorithm for detecting a single sinusoid of unknown frequency corrupted by Gaussian noise has been proposed by Nishimura et al. using IIR bandpass filter with a variable center frequency/sup [1]/. The filter has the parallel block structure for fast processing. However, the algorithm has two problems: one is that it has several input frequencies making it impossible to converge; another is that the convergence rate cannot be higher than that of the scalar structure. In this paper, the causes of these problems are investigated and a new algorithm is proposed to solve these problems. Simulation results are given to illustrate the performance of the proposed algorithm.

Design of FIR partial response filter pairs with equiripple stopband attenuation (class I and IV)

The design of FIR (finite-impulse response) partial response transmitter and receiver filter pairs for class I and IV is described. Each filter is designed to have equiripple stopband attenuation. For class I, the filters form a matched filter pair, while for class IV, the filters have nearly equal stopband attenuation. Moreover, the overall impulse response of each filter pair is approximated to produce minimum intersymbol interference. Two design examples are presented. One is a 57th-order class I filter pair having 0.05% ISI (intersymbol interference). The other is a class IV 61st-order transmitter and 57th-order receiver filter pair whose ISI is 0.2%.<<ETX>>

Image Polynomial And Its Applications To Image Restoration

This paper proposes the image polynomial as an image descriptor. An image polynomial is defined by a power series whose coefficients coincide with gray levels of a digital image. And orders of an image polynomial agree with locations of pixels of a digital image. The image polynomial is also suitable to describe a shift-invariant image formation system. Furthermore, we derive an iterative image restoration algorithm which yields the original clear image by a finite number of iteration.

A construction method of optimum integer-to-integer transform based on an error propagation model

In lossless image compression, a ladder network is commonly or widely used for integer to integer transform(integer transform), where rounding operations after multiplications cause some difference between the real and integer transform (transform error). In order to remain the error value within a small range, the ladder network coefficients should be small. We previously proposed a method of exchanging the rows of transformation matrix(row exchange method) to make the ladder network coefficients smaller. As there are many exchange patterns, a method is desired for finding best or nearly best exchange pattern efficiently. This paper proposes such a method by maximizing the absolute value of trace of a submatrix of the transformation matrix.