This is a brief introduction to image science and engineering education at Chiba University. A short history and the present status of the education are given, and an outline of the newly established PhD program in image science is described.

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The construction of a serial (triple) exposure type of high intensity flash x-ray generator having variable energies for biomedical radiography is described. This generator consisted of the following components: two high voltage generators (positive and negative), two voltage dividers, two types of high and low voltage pulsers with as (SF⁶) gap switches, small-sized triver devices with a voltage of about -50 kV, a trigger control system with three light outputs with a time resolution of under a microsecond, a high power gas diode with three terminals using field emission, one turbo molecular pump, and two evacuated remote flash x-ray tubes, each of a new and different type with a coaxial cable. In the case of using a single flash x-ray tube, the pulsers were charged to the same or different energies from - 100 kV to+100 kV by using two voltage dividers and were connected to the flash x-ray tube through a hi: power diode.

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It is necessary for study of the MTF measurement method to know true MTF. Photographic characteristic curve, noise and MTF were modeled on the basis of experimental data. Density porofiles for five methods were obtained with simulations of imaging process by the use of the models. MTF's were measured from the density profiles under a number of conditions of sampling and calculation Measured MTF's were compared with true MTF modeled, and an optimal measurement condition was determined for each method. It was found that the slit method with the multiple-exposure technique was the most accurate one.

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Dependence of relative exposures at surface position of objects and mAs values on high-voltage ripple-rate was estimated using X-ray spectra and spectral speeds of the six screen-film systems. It has been verified quantitatively that 3-phase X-ray units are better than single-phase X-ray units from the view points of patient exposure and image quality in diagnostic radiology.

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A new spectrophotometer of measuring the spectrum for the stomach membrane has been developed. This spectrophotometer is composed of the Endoscope, optical multichannel spectral analyzer and microcomputer, which can measure the spectrum of the stomach membrane from 350 nm to 830 nm instantaneously. The chromaticity values of color transparency taken by the endoscope and the values measured by a new spectrophotometer are compared and analyzed. Based on these experimental results, we are considering the method to improve color reproduction in endoscopic imaging system.

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In this paper three methods are used to interpolate the CT image data in the axial direction for three dimensional display of them. The methods used here are (1) polynomial interpolation, (2) a method based on geometrical mean or mean square and (3) a method using partial cross-correlation function. From the results of computer simulation, it is concluded the method using partial crosscorrelation function gives good results though the processing needs much computer time. Some results on CT images are also presented.

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In computed tomography, the reprojection from provisionally reconstructed image is often needed, and a few kinds of algorithms have been usedfor that purpose. But no conventional reprojection algorithm corresponds to the Radon transform in the continuous field, and the analytically accurate reprojection algorithm has been desirable. This paper proposes a reprojection algorithm based on the Radon transform in the continuous field, and the superiority of the newly proposed algorithm to the conventional ones have been proved through the computer simulation.

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The image degraded by signal-dependent noise can not be as treated a stationary random field. We divide the image into subimages in which the stationarity assumption is satisfied. The restored image is composed of subimages restored by SSIR method. Based on a subjective visibility function, which gives the relationship between the visibility of a unit noise and a measure of local spatial detail, we develop a new restoration system which improve the image blurred by the noise reduction system. Some examples are given to illustrate the performance of the new image restoration system.

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