Showing papers by "Nagaaki Ohyama published in 2005"

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

Color reproduction system for making color display of four or more primary colors based on input tristimulus values

Abstract: A display apparatus includes a color image projection unit and a screen. The color image projection unit includes a converter which receives image signals of three primary colors, and converts the received image signals of three primary colors into image signals of four or more primary colors, and a color image projector which includes a plurality of image projection devices having respective primary colors, and which receives the image signals of four or more primary colors, and projects the received image signals of four or more primary colors onto the screen. The color image projector is capable of physically adjusting positions of the image signals of four or more primary colors, which are projected onto the screen such that the positions of the image signals are coincident with each other.

Transaxial system models for jPET-D4 image reconstruction.

Abstract: A high-performance brain PET scanner, jPET-D4, which provides four-layer depth-of-interaction (DOI) information, is being developed to achieve not only high spatial resolution, but also high scanner sensitivity. One technical issue to be dealt with is the data dimensions which increase in proportion to the square of the number of DOI layers. It is, therefore, difficult to apply algebraic or statistical image reconstruction methods directly to DOI-PET, though they improve image quality through accurate system modelling. The process that requires the most computational time and storage space is the calculation of the huge number of system matrix elements. The DOI compression (DOIC) method, which we have previously proposed, reduces data dimensions by a factor of 1/5. In this paper, we propose a transaxial imaging system model optimized for jPET-D4 with the DOIC method. The proposed model assumes that detector response functions (DRFs) are uniform along line-of-responses (LORs). Then each element of the system matrix is calculated as the summed intersection lengths between a pixel and sub-LORs weighted by a value from the DRF look-up-table. 2D numerical simulation results showed that the proposed model cut the calculation time by a factor of several hundred while keeping image quality, compared with the accurate system model. A 3D image reconstruction with the on-the-fly calculation of the system matrix is within the practical limitations by incorporating the proposed model and the DOIC method with one-pass accelerated iterative methods.

Color correction of pathological images based on dye amount quantification

Abstract: Pathological images are color images of stained tissue slides, the color of which varies depending on staining conditions. For reliable diagnosis, the color variation must be corrected in these images. This paper proposes a color correction method for hematoxylin and eosin (H&E) stained pathological images in which the amounts of H&E dyes are estimated based on multispectral imaging technique and Beer Lambert law, and the color image is generated corresponding to the adjusted amount of dyes. This enables us to correct an image to an arbitrary or specified optimal staining-condition image. Through experiments using H&E stained human liver slide images, the effectiveness of the proposed method was confirmed.

Multispectral color imaging for dermatology: application in inflammatory and immunologic diseases

Abstract: This paper presents an experimental investigation of the application of multispectral imaging in dermatology. The focus areas of this work are as follows: a) the improving the color reproduction accuracy of skin lesions, b) exploring the spectral feature of skin disease using the multispectral color enhancement technique, and c) multispectral image analysis aiming at supporting quantitative diagnosis. The experiment focused on inflammatory and immunologic diseases; the color of skin lesions associated with these diseases is believed to be difficult to reproduce by conventional imaging devices. In view of this fact, we demonstrate the effectiveness of using spectral information for the color reproduction and quantitative analysis of skin disorders.

Development of a 16-band multispectral image archiving system

Abstract: To preserve museum collections of works of art, these collections are often photographed for display in digital museums. However, conventional photography cannot capture spectral characteristics of objects. In this paper, we describe a 16-band camera system designed to produce spectral images of ancient paintings. Results of color reproduction of captured images and results of spectral analysis of images of ancient paintings are also presented. The camera consists of a 2000×2000-pixel CCD, a rotational filter turret with 16 interference filters, and a PC-based image capturing and displaying unit. The camera's lens is interchangeable, and it enables two or more different view sizes. Each band image of the camera can be focused independently, and it reduces longitudinal chromatic aberration. A stroboscope is used for lighting, and the rotational filter turret and electrical shutter of the CCD have been synchronized with it. An electric motor-driven photographic platform is used to enable photographing large objects in several shots. We evaluated the results of color estimation for an image taken by this camera using the GretagMacbeth ColorChecker 24-color chart. The average ΔEab was 2.09 (maximum ΔEab was 4.03). Spectral reflectance were used to analyze a degraded area on an ancient painting.

Digital Staining of Unstained Pathological Tissue Samples through Spectral Transmittance Classification

Abstract: Histological structures of a pathological tissue sample convey information relevant to the diagnosis of the disease that might have afficted the person. To reveal the morphology of these structures clearly, pathological tissues are stained. In this paper, a digital staining methodology for pathological tissue samples is introduced. Digital staining implies the application of digital processing techniques to transform the image of an unstained sample to its stained image counterpart. In the method, the transmittance spectra of the unstained and Hematoxylin and Eosin (H&E) stained multispectral images (16 bands) of specific tissue components are utilized. Two experiments were conducted to probe the possibility of the digital staining framework: the linear mapping of spectral transmittances, and the classification of spectral transmittances in conjunction with the linear mapping of specific transmittance data sets. The method classified the four tissue components, e.g. nucleus, cytoplasm, red blood cells, and the white region (region devoid of tissue structures), while the misclassifications between components with spectral transmittances that are closely similar were not completely rectified. © 2005 The Optical Society of Japan

Color Enhancement in Multispectral Image Using the Karhunen-Loeve Transform

Abstract: We propose a new method for the color enhancement of multispectral image in the visible wavelength region. The purpose of the proposed method is to explore the weak features contained in a specific wavelength by discounting the major color distribution. Such examination will be valuable in visual inspection applications, for example, a medical examination using color image to find a small spectral change of an abnormal part. In this method, Karhunen-Loeve (KL) transform is applied to multispectral data, and specific wavelength components of only high-order KL coefficients are amplified while low-order coefficients are not changed to retain the major color distribution. In the experiment, this method was applied to multispectral images: a printed test image and a human skin image of a bruised arm were captured by a 16-band multispectral camera. The resultant images were compared with the images obtained by saturation enhancement and that obtained by applying the proposed method to the 3-band image. The method successfully visualized the features, which are almost invisible in natural color images, with less change in background color than saturation enhancement.

Digital staining of pathological tissue specimens using spectral transmittance

Abstract: Staining of tissue specimens is a classical procedure in pathological diagnosis to enhance the contrast between tissue components such that identification and classification of these components can be easily performed. In this paper, a framework for digital staining of pathological specimens using the information derived from the L-band spectral transmittance of various pathological tissue components is introduced, particularly the transformation of a Hematoxylin and Eosin (HE) stained specimen to its Masson-Trichrome (MT) stained counterpart. The digital staining framework involves the classification of tissue components, which are highlighted when the specimen is actually stained with MT stain, e.g. fibrosis, from the HE-stained image; and the linear mapping between specific sets of HE and MT stained transmittance spectra through pseudo-inverse procedure to produce the LxL transformation matrices that will be used to transform the HE stained transmittance to its equivalent MT stained transmittance configuration. To generate the digitally stained image, the decisions of multiple quadratic classifiers are pooled to form the weighting factors for the transformation matrices. Initial results of our experiments on liver specimens show the viability of multispectral imaging (MSI) for the implementation of digital staining in the pathological context.

A visual evaluation of the image reproduced on a multiprimary display by color decomposition based on spectral approximation

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.

File Encryption Software Using Fingerprint Keys Based on Double Random Encoding

Abstract: The encryption method based on double random phase encoding makes it possible to use the fingerprints as cipher key. Applying this technique, we develop a file encryption software which can use fingerprint as cipher key.

Spectral-based image-editing system

Abstract: An image editing system that deal with spectral reflectance instead of RGB values in retouching or changing the color of an object is proposed, for the purpose to achieve high accuracy and enhanced functionality in color reproduction.

Improvements for multispectral image compression for color reproducibility with preservation to spectral accuracy

Abstract: This paper proposes a method for multispectral image compression that makes multispectral image applicable for both color reproduction and spectral image analysis. In the methods previously proposed for colorimetric error reduction, the weighting matrices were incorporated to Karhunen-Loeve transform (KLT) as the spectral transform for compression, which account for the color matching functions of human observer and the viewing illuminant. However, the improvement for color reproducibility is on the cost of spectral accuracy degradation. In this paper, we show the reduction of colorimetric error and the preservation of spectral accuracy is a tradeoff that can be controlled by adding a diagonal matrix to the weighting matrix of KLT. Experimental results using the proposed method integrated with JPEG2000 for a 16-band multispectral image show that spectral accuracy is improved without substantial colorimetric loss by the addition of diagonal matrix if the magnitude of the diagonal matrix is chosen appropriately.