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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.


Papers
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Proceedings Article
01 Jan 2008
TL;DR: A modified color correction method that can appropriately correct the color of RBC areas in H&E stained images is proposed and the effectiveness of the proposed method was shown with respect to the color difference between reference and test slides in CIE-LAB space.
Abstract: The color of stained pathological images varies depending on staining conditions. Since pathologists based their diagnosis on changes in color and morphology of a particular tissue component, it is important that color variations in stained pathological images be corrected so as to obtain a more reliable diagnosis. A color correction for Hematoxylin & Eosin (H&E) stained images was proposed previously. However, the method did not successfully correct the color of red blood cell (RBC) but only the nucleus and cytoplasm. In this paper, a modified color correction method that can appropriately correct the color of RBC areas in H&E stained images is proposed. In the method, a different weighting coefficient was assigned to RBC areas, which was based from averaged dye amount ratio in RBC areas in reference and test slides, and a new basis function was derived, in addition to the original three bases functions, to represent the change in the absorption coefficient in RBC areas. In the experiment, the effectiveness of the proposed method was shown with respect to the color difference between reference and test slides in CIE-LAB space.

6 citations

Journal Article
TL;DR: An algorithm is developed for the spectral approximation method that algebraically derives an optimal solution and yields more precise results with less computational cost than Murakami's one.
Abstract: When the number of primary colors, N, is greater than three, the solutions that present the same XYZ values have N - 3 dimensional freedom. A multiprimary display expands the color gamut and also produces many sets of display signals that present a given set of XYZ tristimulus values, so it can utilize the degrees of freedom. The spectral approximation method is thus well suited for multiprimary displays. It minimizes the difference between the original spectrum and the reproduced spectrum under the constraint of a tristimulus match for a CIE standard observer, so it should reduce the color mismatch for any color matching function. However, this had not been confirmed using actual images. The spectral approximation method may not work well for actual images because such images usually have many colors and shadings, and interactions among them might reduce its effectiveness. Since multiprimary displays are becoming commonly used for electronic commerce, telemedicine, etc., confirming the effectiveness of this method is important. Therefore we conducted a visual experiment using actual images to determine its performance. Comparison with other decomposition methods that do not use spectral approximation suggests the effectiveness of the spectral approximation method. We also developed an algorithm for the spectral approximation method that algebraically derives an optimal solution and yields more precise results with less computational cost than Murakami's one.

6 citations

Journal Article
TL;DR: In this paper, a linear combination of the multispectral images as interpolation function is proposed, which is equivalent to fitting the data to a straight line in a 16-dimentional space.
Abstract: We present a proposal to achieve accurate color reproduction by fitting the CIE-XYZ tristimulus values of a given color stimulus, and using the 16-band multispectral images, as well as the CIE-XYZ tristimulus values of a known color test chart. We propose a simple linear combination of the multispectral images as interpolation function, which is equivalent to fitting the data to a straight line in a 16-dimentional space. By using this interpolation function, we minimize the merit function of the mean error between the measured and estimated CIEXYZ tristimulus values of the color test chart. We show, by making a visual comparison between the results achieved using this proposal and the results achieved using a spectral reflectance estimation technique, that the proposed interpolation function when using 16-channel multispectral images produces high quality results in terms of color reproduction fidelity.

6 citations

Journal ArticleDOI
TL;DR: In this paper, a new method for fringe pattern analysis is proposed, which needs the introduction of defocusing into the fringe patern, and the fringe pattern with defocusing is analyzed using a 2D Fresnel transform.

6 citations

Journal ArticleDOI
TL;DR: An advanced coded imaging system is described, and some results of phantom experiments are presented, and it may be concluded that the new system is useful for practical applications, for example, to nuclear medicine.
Abstract: An advanced coded imaging system is described, and some results of phantom experiments are presented. The advanced method uses a pair of coherent codes (+1 and −1 codes) and has many advantages compared with conventional ones. One of the greatest advantages is that there are no sidelobes in the focal plane and only a few in other planes. Therefore, when an object can be regarded as two-dimensional, it is perfectly reconstructed with high detecting efficiency, and this is successfully simulated by a thyroid phantom with 99mTc. Moreover, this system has an ability to reconstruct tomograms, which is also shown by using ring phantoms piled on one another with some cold spots in their shells. From these experimental results it may be concluded that the new system is useful for practical applications, for example, to nuclear medicine.

5 citations


Cited by
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Journal Article
TL;DR: In this article, a fast Fourier transform method of topography and interferometry is proposed to discriminate between elevation and depression of the object or wave-front form, which has not been possible by the fringe-contour generation techniques.
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.

3,742 citations

Patent
29 Aug 2006
TL;DR: In this paper, 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, is presented.
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.

2,644 citations

Patent
06 Jun 1995
TL;DR: 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, is presented for confirmation by the user, and the predictive mechanism is updated based on this feedback as mentioned in this paper.
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.

1,976 citations

Proceedings ArticleDOI
Jing Huang1, S.R. Kumar1, Mandar Mitra1, Wei-Jing Zhu1, Ramin Zabih1 
17 Jun 1997
TL;DR: Experimental evidence suggests that this new image feature called the color correlogram outperforms not only the traditional color histogram method but also the recently proposed histogram refinement methods for image indexing/retrieval.
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.

1,956 citations

Journal Article
TL;DR: In this article, a self-scanned 1024 element photodiode array and a minicomputer are used to measure the phase (wavefront) in the interference pattern of an interferometer to lambda/100.
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.

1,300 citations