Atsushi Koike

A Study on Biometric Authentication based on Arm Sweep Action with Acceleration Sensor

A new biometrics authentication method for cellular phones which has an advantage of simple and natural operation is proposed. The proposed method authenticates owner using acceleration signals obtained by an acceleration sensor embedded in the cellular phones during his arm sweep action. When the owner wants to unlock its security, he just needs to grasp and shake his cellular phone. The proposed method verifies owners acceleration signals by using a DP-matching algorithm which can adapt fluctuations caused by different grip. Simulation results show that the proposed method can achieve the best equal error rate 5.0% for 22 testers

A Bit-Plane Coding Scheme of MPEG-4 FGS with High Efficiency Based on the Distribution of Significant Coefficients

MPEG-4 FGS video coding can perform video transmission with adaptation to channel bandwidth variation on the network. However, binary zero-run-length coding used by FGS decreases its coding efficiency in the lower bit-plane. In this paper, we propose a new coding scheme improving coding efficiency in the lower bit-plane. Based on the distribution of a significant coefficient, each bit is classified into two groups. At the same time, information that raises picture quality higher than any other coefficient is coded first. Simulation results show that this proposed scheme improves the coding efficiency up to more than 1.06%, and achieves 0.2dB gain in terms of average PSNR.

Tile boundary artifact reduction algorithms for tile size conversion of wavelet image

This paper proposes the tile size conversion method for the wavelet image transcoding gateway and a set of methods to reduce the tile boundary artifacts caused by the conversion.In the wavelet image coding system represented by JPEG2000, pictures are usually divided into one or more tiles and each tile then transformed separately. On low memory terminals such as mobile terminals, some decoders are likely to have limits on what tile sizes they can decode. Assuming a system using these limited decoders, methods were investigated for converting the tile size quickly and automatically at the gateway when image data with a non-decodable tile size is received at the gateway from another system. Furthermore, tile boundary artifacts reduction methods are investigated. This paper proposes a basic method, which creates a tiled wavelet coefficient sequence from a non-tiled wavelet coefficient sequence. This paper also verifies the validity of the proposed scheme by implementing it with a 5x3 reversible filter and a 9x7 irreversible filter.