Yuri Ohya

Bio: Yuri Ohya is an academic researcher from Tokyo Institute of Technology. The author has contributed to research in topics: Color image & False color. The author has an hindex of 5, co-authored 5 publications receiving 289 citations.

Color image processing apparatus

Abstract: A color image processing apparatus reproduces color data of a subject at higher accuracy by estimating the spectral reflectance of the subject from the color chip basis function vn (λ) which can expand the spectral reflectances of all color chips of the reference chart and the expansion coefficients B of the color chips The color image processing apparatus uses an image processing device to which a subject shooting signal Q shot by the color image input device and a reference chart shooting signal G taken from a plurality of color chips each having a spectral reflectance, is known

Natural color reproduction in the television system for telemedicime

Abstract: In the telemedicine application through visual communication systems, the reproduction of color is quite important. The purpose of this work is to develop a method for the reproduction of the natural color of the object in the TV system for telemedicine. When the illumination of observation environment is different form the object illumination, the change in color perception is caused by the color adaptation of human vision. In the method presented in this paper, the difference of illumination condition is corrected by using multispectral information captured by a multispectral camera. This paper shows the methods and the basic results for the reproduction of two types of color; the reproduction of color image as if the object is directly observed, and the reproduction of color appeared when the object is placed under the observation condition.

Natural color reproduction system for telemedicine

Abstract: The color information of a patient image is quite important in telemedicine systems, but is not correctly reproduced by conventional color imaging systems. In this paper, we present a natural color reproduction system for telemedicine. In this system, the illumination difference between the image capturing site and observation site is corrected using a multispectral image, and the color image is displayed on a calibrated display device. For improvement of the color reproduction accuracy, the principal components of spectral reflectances are utilized in the color measurement. The accuracy of color reproduction in the developed system is experimentally evaluated. As a result, it is confirmed that the system realizes good accuracy in the color reproduction of human skin from a five band multispectral image.

Natural color reproduction of human skin for telemedicine

Abstract: For a reliable diagnosis through visual telecommunication systems, it is very important to reproduce patient images with correct color. Natural color television system previously proposed is capable of reproducing the original color of the objects using multispectral images, even when the illumination environment for observing images is different from the illumination used for recording. In this paper, to render this system practical for telemedicine system, we reduce the number of color bands of multispectral camera by utilizing the principal components of spectral reflectances in human skin class. In addition, we investigate a simple method, using color charts, to obtain the recording information of both illumination and camera. As color chart selection criterion, it becomes clear that principal components for human skin class need to be described by the linear combination of spectral reflectances of color charts. Principal components for human skin class are obtained through measurements and analysis of 484 human skin spectral reflectances. In the experiment, natural color reproduction for human skin is realized from limited number of color bands using color charts for acquiring the recording information instead of spectral measurement devices.

Natural color reproduction system for telemedicine and its application to digital camera

Abstract: For a reliable diagnosis via visual telecommunication systems, it is very important to reproduce patient images with correct color. But it is not certain by conventional color imaging systems especially when the illumination of observing site is different from that of the image capturing site. We present a natural color reproduction system for telemedicine. In this system, the color of a patient under observing illumination is calculated from multispectral image. For accurate color reproduction, the spectral reflectance is calculated using principal components of human skin in the process. The color image is displayed on a calibrated display device. In the experiment, it is confirmed that the system realizes good accuracy in the color reproduction of human skin from 10 band multispectral image. And for simplification of the system we also adapted this process to commercial digital RGB camera.

Omnidirectional imaging apparatus

Abstract: An omnidirectional image apparatus (130) for sensing an image of a substantially hemispherical scene from a single viewpoint, including a truncated, convex, substantially paraboloid-shaped reflector (135) positioned to orthographically reflect an image of the substantially hemispherical scene, and an image sensor (110) positioned to receive the orthographically reflected image. An omnidirectional image projection apparatus for projecting an image of a substantially hemispherical scene as viewed from a single viewpoint, including a means for projecting a collimated beam of light modulated with the image, and a truncated convex substantially paraboloid-shaped reflector positioned to orthographically reflect the collimated beam of light modulated with the image to project the hemispherical scene.

Color calibration of color image rendering devices

Abstract: Color calibration of color image rendering devices, such as large color displays, which operate by either projection or emission of images, utilize internal color measurement instrument or external color measurement modules locatable on a wall or speaker. A dual use camera is provided for a portable or laptop computer, or a cellular phone, handset, personal digital assistant or other handheld device with a digital camera, in which one of the camera or a display is movable with respect to the other to enable the camera in a first mode to capture images of the display for enabling calibration of the display, and in a second mode for capturing image other than of the display. The displays may represent rendering devices for enabling virtual proofing in a network, or may be part of stand-alone systems and apparatuses for color calibration. Improved calibration is also provided for sensing and correcting for non-uniformities of rendering devices, such as color displays, printer, presses, or other color image rendering device.

Independent-component analysis of skin color image

Abstract: The spatial distributions of melanin and hemoglobin in human skin are separated by independent-component analysis of a skin color image. The analysis is based on the skin color model with three assumptions: (1) Spatial variation of color in the skin is caused by two pigments, melanin and hemoglobin; (2) the quantities of the two pigments are mutually independent spatially; and (3) linearity holds among the quantities and the observed color signals in the optical density domain. The results of the separation agree well with physiological knowledge. The separated components are synthesized to simulate the various facial color images by changing the quantities of the two separated pigments.

Method and apparatus for correcting luminance and chrominance data in digital color images

Abstract: The present invention is directed to a method and apparatus for improving the efficiency of color correcting subsampled luminance and chrominance based data. More specifically, the present invention is directed to a method of applying a full conversion between color spaces for one pixel in a selected pixel block. Chrominance values are assigned to the remaining pixels based upon their luminance values relative to the luminance value of the converted pixel. The invention may be used to convert between various types of color spaces, and may be used in the processing of both device dependent and device independent data.

System and methods for aging compensation in AMOLED displays

Abstract: Circuits for programming, monitoring, and driving pixels in a display are provided. Circuits generally include a driving transistor to drive current through a light emitting device according to programming information which is stored on a storage device, such as a capacitor. One or more switching transistors are generally included to select the circuits for programming, monitoring, and/or emission. Circuits advantageously incorporate emission transistors to selectively couple the gate and source terminals of a driving transistor to allow programming information to be applied to the driving transistor independently of a resistance of a switching transistor.