Toshiyuki Yoshitake

An MPEG-4 video LSI with an error-resilient codec core based on a fast motion estimation algorithm

An MPEG-4 video codec core based on a scene-adaptive motion estimation algorithm is integrated into 5.296/spl times/5.296 mm/sup 2/ die using 0.18 /spl mu/m quad-metal technology. The power dissipation during codec operation of the device is 131 mW for QCIF format at 15 frames/s at 13.5 MHz using a 1.5 V supply.

Low power MPEG-4 ASP codec IP macro for high quality mobile video applications

This work presents a low power MPEG-4 ASP (advanced simple profile) codec IP macro suitable for high quality mobile video applications. By introducing a motion estimation algorithm suitable for low power applications and a field/frame mode estimation algorithm for interlaced video, this IP macro achieves higher compression efficiency and image quality than previous SP (simple profile) codec LSIs.

Prototype of image compression system for medical images

We previously developed an image reconstruction display for reconstructing images compressed by our hybrid compression algorithm. The hybrid algorithm, which improves image quality, applies Discrete Cosine Transform coding (DCT) and Block Truncation Coding (BTC) adaptively to an image, according to its local properties. This reconstruction display receives the compressed data from the host computer through a BMC channel and quickly reconstructs good quality images using a pipeline-based microprocessor. This paper describes a prototype of a system for compression and reconstruction of medical images. It also describes the architecture of the image compression processor, one of the components of the system. This system consists of the image compression processor, a host main-frame computer and reconstruction displays. Under this system, distributed processing in the image compression processor and the image reconstruction displays reduces the load on the host computer, and supplies an environment where the control routines for PACS and the hospital information system (HIS) can co-operate. The compression processor consists of a maximum of four parallel compression units with communication ports. In this architecture, the hybrid algorithm, which includes serial operations, can be processed at high speed by communicating the internal data. In experiments, the compression system proved effective: the compression processor compressed a 1k x 1k image in about 2 seconds using four compression units. The three reconstruction displays showed the image at almost the same time. Display took less than 7 seconds for the compressed image, compared with 28 seconds for the original image.

Handheld Guides in Inspection Tasks: Augmented Reality versus Picture

Inspection tasks focus on observation of the environment and are required in many industrial domains. Inspectors usually execute these tasks by using a guide such as a paper manual, and directly observing the environment. The effort required to match the information in a guide with the information in an environment and the constant gaze shifts required between the two can severely lower the work efficiency of inspector in performing his/her tasks. Augmented reality (AR) allows the information in a guide to be overlaid directly on an environment. This can decrease the amount of effort required for information matching, thus increasing work efficiency. AR guides on head-mounted displays (HMDs) have been shown to increase efficiency. Handheld AR (HAR) is not as efficient as HMD-AR in terms of manipulability, but is more practical and features better information input and sharing capabilities. In this study, we compared two handheld guides: an AR interface that shows 3D registered annotations, that is, annotations having a fixed 3D position in the AR environment, and a non-AR picture interface that displays non-registered annotations on static images. We focused on inspection tasks that involve high information density and require the user to move, as well as to perform several viewpoint alignments. The results of our comparative evaluation showed that use of the AR interface resulted in lower task completion times, fewer errors, fewer gaze shifts, and a lower subjective workload. We are the first to present findings of a comparative study of an HAR and a picture interface when used in tasks that require the user to move and execute viewpoint alignments, focusing only on direct observation. Our findings can be useful for AR practitioners and psychology researchers.

Fast and accurate relocalization for keyframe-based SLAM using geometric model selection

In this paper, we propose a relocalization method for keyframe-based SLAM that enables real-time and accurate recovery from tracking failures. To realize an AR-based application in a real world situation, not only accurate camera tracking but also fast and accurate relocalization from tracking failure is required. The previous keyframe-based relocalization methods have some drawbacks with regard to speed and accuracy. The proposed relocalization method selects two algorithms adaptively depending on the relative camera pose between a current frame and a target keyframe. In addition, it estimates a degree of false matches to speed up RANSAC-based model estimation. We present effectiveness of our method by an evaluation using public tracking dataset.

Low memory usage architecture for 3D graphics based on scan-line rendering

We propose a novel 3D graphics architecture based on scan-line rendering. Scan-line rendering does not require a frame buffer and depth buffer, therefore it can reduce memory usage as compared with the widely used frame buffer architecture. On the other hand, scan-line rendering requires a huge volume of memory access. Some algorithms to solve this problem were proposed in the field of 2D graphics, but more improvement to reduce memory usage is required for embedded devices of 3D graphics. To achieve low memory usage in 3D rendering, we developed an effective algorithm to restructure polygon data in the scan-line order. Furthermore we developed a novel vertex cache that utilizes the characteristics of scan-line rendering. As a result, we succeeded in reducing memory usage by about 80% in comparison with the frame buffer method while maintaining the volume of memory access at the same level.