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This study proposes a piecewise Wiener estimation method to reconstruct a spectral reflectance image from a three-band image by multipoint spectral information collected simultaneously with image acquisition. A three-band image is divided into several blocks and the spectral estimation is carried out using the Wiener estimation matrix assigned to each block. Each Wiener estimation matrix is constructed on the basis of spectral measurement data. The experimental results show that the proposed method reduces the average estimation error monotonically as the number of spectral measurements increases. In addition, the computational time of the piecewise Wiener estimation costs only several fold of the computational time of the conventional single-matrix method. OCIS codes: 100.2000, 100.3010, 110.4234, 330.1690.

Accurate color image reproduction under arbitrary illumination can be realized if the spectral reflectance functions in a scene are obtained. Although multispectral imaging is one of the promising methods to obtain the reflectance of a scene, it is expected to reduce the number of color channels without significant loss of accuracy. This paper presents what we believe to be a new method for estimating spectral reflectance functions from color image and multipoint spectral measurements based on maximum a posteriori (MAP) estimation. Multipoint spectral measurements are utilized as auxiliary information to improve the accuracy of spectral reflectance estimated from image data. Through simulations, it is confirmed that the proposed method improves the estimation accuracy, particularly when a scene includes subjects that belong to various categories. OCIS codes: 100.3010, 100.3190, 110.2990, 300.6550.

Nonlinear estimation method of spectral reflectance from camera responses is proposed. The proposed method minimizes the mean square error of spectral reflectance when the reflectance can be regarded as a random sequence of Gaussian mixture distribution. In computer simulations, 168 samples of spectral reflectance from a color chart are estimated from their image signals obtained by three- and six-band cameras. It is confirmed that the proposed method improves the accuracy in comparison with the conventional Wiener estimation method. OCIS codes: 100.2000, 100.3190, 300.6550, 330.1690.

A method for estimating electrical current distribution in the human brain using a multiple current dipole model is presented. A cost function for estimating multiple dipoles is proposed and a simulated annealing algorithm is used to obtain an acceptable solution. Computer simulation is used to evaluate the effectiveness of this method.

This paper describes the details of the simulated annealing algorithm proposed to estimate the parameters of multiple current dipoles using biomagnetic data. The paper discusses the effects of the choices of such numerical conditions as the amount of estimate transitions, the equilibrium criterion, and the temperature decrement on the algorithm's performance. Incorrect results from the computer simulation obtained with inappropriate choices of such conditions are presented. The verification of a near-optimum convergence by reheating and reannealing is demonstrated. A modification of this algorithm is proposed for implementation by parallel computer, and the validity of this parallel algorithm is also demonstrated by computer simulation.

We propose a holographic three-dimensional (3-D) printer that produces 3-D hard copies of computer data. A new technique for synthesizing a holographic stereogram (HS) has been invented for the purpose of making accurate hard copies of 3-D objects. The flat-format, Lippmann-type HS is printed by one optical step and is ideally suitable for 3-D printer application. This type of HS has both horizontal and vertical parallaxes so that the reconstructed image is free from distortion. The principle and the image quality of this type of HS are described, and a reconstructed image from this type of HS with 160 x 128 elements is experimentally demonstrated. The systematic constitution of a holographic 3-D printer is also discussed. Key words: Holography, displays, three-dimensional image processing, hard copies, holographic stereograms.