The principle and features of holography are surveyed. The conventional three-dimensional imaging techniques are briefly reviewed in the relation of holography. The three-dimensional vision of the medical pictures is discussed for the application of holography to medicine.

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Synchrotron Radiation (SR) is electromagnetic radiation that has enoumous intensity and applicable energy by using wiggler magnet for radiology. One of useful applications of SR is a technique of digital energy subtraction by using two monochromatic X-rays which have energies slightly above and below the energy of K-absorption edge of an X-ray contrast medium. It is so called K-edge dichromography. The paper presents some basic results obtained at the photon factory in national laboratory for high energy physics (KEK), Japan. (1) Spatial resolution: superior resolution than conventional X-ray even with a distance of 50cm between a test chart and a detector (non-screen type X-ray film), and different resolution for the longitudinal and horizontal, the former is better. (2) Density resolution: clearly resolved 1.4mg/cm² in iodine wedge phantom by taking dichromography.

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Point response and image distortion of ultrasonic diagnostic system are investigated. The echogram for a thin wire target is shaped like a letter T. The horizontal or transversal bar is originated from directivity of the ultrasonic beam, and the vertical or axial bar multireflection effect in the target. If the targets are in the second medium, ultrasonic beam will be deflected at the boundary of the first and the second media. Snell's law of optics can be applied to calculate the displacement of the image of the targets. Experiments and calculations show fairly good agreement.

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Although ultrasonic transmission computed tomography has been extensively discussed in the literature, only parallel-beam geometry has been considered. With this geometry, reconstruction accuracy is limited by the tradeoff between refraction loss and phase, cancellation. The new topic of this paper is tomographic imaging with fan-beam geometry. By adopting fan-beam geometry, we can expect not only reduction of measurement time but also (1) no refraction loss, (2) reduction of phase cancellation, and (3) ease of designing the ultrasonic transducers.
In this paper, the reconstruction quality is discussed under an approximation of geometrical optics. Projection formation was simulated by a digital computer and tomographic images were reconstructed from the simulated projections. Only objects with faster acoustic velocity than the surrounding medium were considered. For these objects, the acoustic beam diverges and the projections broaden. This causes enlargement of area of the reconstructed objects. Acoustic velocity images have their edges blurred, while attenuation images have relatively clear edges. Compensation of refraction is possible for attenuation images by an algebraic reconstruction technique by referring to a reconstructed velocity image. It was also found that reflection loss appears as large values of the attenuation coefficient if there is a large difference of acoustic impedance between the object and the surrounding medium. medium.

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This paper is concerned with a method of partitioning a piece of image into some subimages with the same statistical properties. To begin with, assuming the image to be a realization from Markov random field, and using the definition of two-dimensional, discrete Markovian field by J. W. Woods, we introduced the probability density function describing the subimages. And employing the Kullback's divergence measuring the distance between these subimages and transforming above distance, we derived the measure of similarity to all pair of subimages. Measure of similarity derived above, however, does not satisfy the equivalence relation, especially, transitive properties. Therefore we established the equivalence relation by carrying out the composition of a fuzzy relation. Thus we can apply this relation to the partition of image. An example is presented for the illustration of this method.

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We applied two restoration systems to noise degraded images; one is the spectral subtraction image restoration (SSIR) system and the other is our modified version. In some restoration system such as Wiener filtering, it is necessary to estimate true image power spectrum. However, these systems are unnecessary to estimate it. In this paper, it is shown by some examples how noise degraded images are improved by the change of parameters. At the suitable parameter selected, the results show that these methods give similar improvement comparing with Wiener filtering technique in root-mean-square error.

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