Nagaaki Ohyama

Bio: Nagaaki Ohyama is an academic researcher from Tokyo Institute of Technology. The author has contributed to research in topics: Color image & Image processing. The author has an hindex of 32, co-authored 258 publications receiving 4480 citations. Previous affiliations of Nagaaki Ohyama include National Institute of Information and Communications Technology.

Multispectral image compression for high-quality color reproduction using JPEG2000

Abstract: Color reproduction systems using multispectral imaging techniques make it possible to accurately reproduce the color of the original object under various viewing illuminants. In this paper, a multispectral image compression method for high fidelity color reproduction is proposed in consideration of color degradation. In the proposed method, a spectral transform and a nonlinear quantization designed to reduce colorimetric error are combined with the discrete wavelet transform in JPEG2000. Through the experiments using some 16-band multispectral images, it is confirmed that the proposed method reduces the average and the maximum color differences in L*a*b* color space in comparison with the conventional methods.

Natural Vision Image Data File Format for Spectral-Based Color Reproduction.

Abstract: Natural Vision Image Data File Format has been developed in order to realize spectral-based color reproduction. This paper introduces the profile format of Natural Vision Image Data File Format. It is based on ICC Profile Format. New Profiles, Tags and Tag Types, therefore, have been developed to cover the lacks of ICC Profile Format for spectral-based color reproduction. The design concepts of Natural Vision System are introduced with respect to the requirements. Input Profiles and Display Profiles are expanded in order to provide spectral characteristics to color reproduction system. ColorSpace Conversion Profiles is expanded in order to provide rendering illuminant and CMFs to Color Reproduction Intent Management System. Relationships between the expanded Profiles and image processing are also descried. Introduction Spectral-based color reproduction system has more flexibility and reliability rather than colorimetric-based one from the viewpoint of colorimetry. The establishment of CIE Technical Committee 8-07 multispectral imaging symbolizes the importance of spectral-based color reproduction. Ohsawa has summarized the concept of spectralbased color reproduction system. The basic architecture of Natural Vision Image Data File Format also has been introduced as the solution of spectral-based color reproduction system. This paper introduces the details of the profile component. Relationship between the profile format and image processing is also explained. Design Concepts of Natural Vision System The following three requirements are established for the design of Natural Vision system: 1) To handle spectral data (R-1) 2) To be acceptable arbitrary illuminants (R-2) 3) To be acceptable arbitrary Color Matching Functions (CMFs) (R-3) 4) To be compatible with current system (R-4) Color reproduction system that realizes the above requirements has the following benefits: a) R-1 overcomes the problems of metameric matching. b) R-2 makes possible illumination exchanges. c) R-3 makes possible optimizations for individual CMFs. d) R-4 gives flexibility to Natural Vision System. Based on the above idea, Natural Vision system is designed as shown in Fig.1. To satisfy R-1, capturing system has to provide spectral reflectance or radiance of the object. Color Reproduction Intent Management System (CRI management system) is in charge of determining color reproduction target. To satisfy R-2 and R-3, CRI Management System has to be acceptable arbitrary illuminants (i.e. Etarget) and CMFs (i.e. ctarget) given by ColorSpace Conversion Profiles. In other words, color reproduction target (i.e. Sestimated,target or Cestimated,target) has to be able to define with the arbitrary illuminants and CMFs. The number of dimension of stimulus value C should be arbitrary. To satisfy R-4, the profile format is based on ICC profile format, AVI or BMP is used as the image format, and WAV format is used as the audio format in Natural Vision Image Data File Format. Figure 2 illustrates the details of the capturing system. It consists of multi-band camera, spectral estimation module and colorimetric estimation module. Input Profiles has to provide spectral characteristics of multi-band camera. The multi-band structure is useful to heighten the accuracy of the spectral estimation. Figure 3 illustrates the details of the CRI management system. It consists of spectral targeting module, colorimetric targeting module. The spectral targeting module is able to accept arbitrary illuminations (i.e. Etarget). The colorimetric targeting module is also able to accept arbitrary CMFs (i.e. ctarget). * The term “stimulus value” corresponds generalized (i.e. multidimensional) XYZ. Tristimulus value is a part of the stimulus value, where the number of dimension is three. ** The term “multi-band” means that the number of bands is arbitrary. Three-band camera (i.e. RGB camera) is included to the multi-band camera. It does not restrict that the number of the bands is over three. IS&T's 2003 PICS Conference

Hierarchical Clustering Method for Extraction of Knowledge from a Large Amount of Data

Abstract: The introduction of information systems in the medical field has made it possible to accumulate a large amount of health care examination data. Analysis of such data could yield valuable new knowledge about health and disease. In this paper, we propose a method for the analysis of large amounts of medical and health care data, especially images or signals. The proposed method treats data in a multidimensional space without any pre-processing, and the data is classified into groups according to the criterion. The criterion used in this paper is to maximize likelihood calculated from the probability density, which is given by the Parzen estimation method. The result of classification is expressed by a binary tree structure as a hierarchy of clusters. We applied this method to computer-generated data and practical electrocardiogram data, and the results showed its validity.

A performance study of the next generation PET using a new histogramming method for the DOI detector

Abstract: The next generation PET scanner named jPET-D4 is being carried out at the National Institute of Radiological Sciences (NIRS) in Japan. At this stage, we plan to apply the reconstruction techniques after the histogramming of list-mode data because it is easy to implement and has low computational cost. The jPET-D4 has 4 layers DOI detectors and it can obtain true list-mode data. However, the conventional histogramming technique is inapplicable to 4 layer DOI detectors, so in this paper we propose a new histogramming method which is suitable for the multi-layer DOI detector. In this method, DOI-PET list-mode data is transformed into sinogram with an accurate system model of the crystal block. We also applied the method to simulated data for the JPET-D4 scanner. Numerical simulation results show that the proposed method reduces sampling error effectively while keeping the advantage of DOI information, and the image quality of JPET-D4 is superior to a conventional nonDOI PET scanner.

Opto-Electronic Block-Cipher Based on Iteration of the 2-D Toggle Cellular Automata: Algorithm

Abstract: Parallel architectures and algorithms may offer a solution to the system bottleneck arising from the need to encrypt a very large amount of data without compromising security. In this respect the use of cellular automata with their parallel, simple, regular and modular structure is very promising. We extend the blockcipher algorithm, based on the iterations of so called “toggle” cellular automata rules to two dimensions.The advantages are higher complexity of the crypt-analytical attacks and substantial increase in the speed of the algorithm. Due to its massive parallelism and interconnectivity, the algorithm is very suitable for opto-electronic implementation.

Fourier-transform method of fringe-pattern analysis for computer-based topography and interferometry

Abstract: A fast-Fourier-transform method of topography and interferometry is proposed. By computer processing of a noncontour type of fringe pattern, automatic discrimination is achieved between elevation and depression of the object or wave-front form, which has not been possible by the fringe-contour-generation techniques. The method has advantages over moire topography and conventional fringe-contour interferometry in both accuracy and sensitivity. Unlike fringe-scanning techniques, the method is easy to apply because it uses no moving components.

Intelligent electronic appliance system and method

Abstract: An intelligent electronic appliance preferably includes a user interface, data input and/or output port, and an intelligent processor. A preferred embodiment comprises a set top box for interacting with broadband media streams, with an adaptive user interface, content-based media processing and/or media metadata processing, and telecommunications integration. An adaptive user interface models the user, by observation, feedback, and/or explicit input, and presents a user interface and/or executes functions based on the user model. A content-based media processing system analyzes media content, for example audio and video, to understand the content, for example to generate content-descriptive metadata. A media metadata processing system operates on locally or remotely generated metadata to process the media in accordance with the metadata, which may be, for example, an electronic program guide, MPEG 7 data, and/or automatically generated format. A set top box preferably includes digital trick play effects, and incorporated digital rights management features.

Ergonomic man-machine interface incorporating adaptive pattern recognition based control system

Abstract: An adaptive interface for a programmable system, for predicting a desired user function, based on user history, as well as machine internal status and context. The apparatus receives an input from the user and other data. A predicted input is presented for confirmation by the user, and the predictive mechanism is updated based on this feedback. Also provided is a pattern recognition system for a multimedia device, wherein a user input is matched to a video stream on a conceptual basis, allowing inexact programming of a multimedia device. The system analyzes a data stream for correspondence with a data pattern for processing and storage. The data stream is subjected to adaptive pattern recognition to extract features of interest to provide a highly compressed representation which may be efficiently processed to determine correspondence. Applications of the interface and system include a VCR, medical device, vehicle control system, audio device, environmental control system, securities trading terminal, and smart house. The system optionally includes an actuator for effecting the environment of operation, allowing closed-loop feedback operation and automated learning.

Image indexing using color correlograms

Abstract: We define a new image feature called the color correlogram and use it for image indexing and comparison. This feature distills the spatial correlation of colors, and is both effective and inexpensive for content-based image retrieval. The correlogram robustly tolerates large changes in appearance and shape caused by changes in viewing positions, camera zooms, etc. Experimental evidence suggests that this new feature outperforms not only the traditional color histogram method but also the recently proposed histogram refinement methods for image indexing/retrieval.

Digital wavefront measuring interferometer for testing optical surfaces and lenses

Abstract: A self-scanned 1024 element photodiode array and minicomputer are used to measure the phase (wavefront) in the interference pattern of an interferometer to lambda/100. The photodiode array samples intensities over a 32 x 32 matrix in the interference pattern as the length of the reference arm is varied piezoelectrically. Using these data the minicomputer synchronously detects the phase at each of the 1024 points by a Fourier series method and displays the wavefront in contour and perspective plot on a storage oscilloscope in less than 1 min (Bruning et al. Paper WE16, OSA Annual Meeting, Oct. 1972). The array of intensities is sampled and averaged many times in a random fashion so that the effects of air turbulence, vibrations, and thermal drifts are minimized. Very significant is the fact that wavefront errors in the interferometer are easily determined and may be automatically subtracted from current or subsequent wavefrots. Various programs supporting the measurement system include software for determining the aperture boundary, sum and difference of wavefronts, removal or insertion of tilt and focus errors, and routines for spatial manipulation of wavefronts. FFT programs transform wavefront data into point spread function and modulus and phase of the optical transfer function of lenses. Display programs plot these functions in contour and perspective. The system has been designed to optimize the collection of data to give higher than usual accuracy in measuring the individual elements and final performance of assembled diffraction limited optical systems, and furthermore, the short loop time of a few minutes makes the system an attractive alternative to constraints imposed by test glasses in the optical shop.