Provides an overview of the technical articles and features presented in this issue.

Beyond HDTV is a very appealing notion for people involved in the development of video systems. Thinking outside the box, such a television system could be constructed in a completely original manner, but to design an actual working system in the present, the system would relate to current HDTV and follow in the footsteps of television systems that have come before it. This being the case, resolution, frame rate, scanning method, colorimetry, aspect ratio, and other parameters must be targeted for study. As for advanced 3DTV systems, a variety of systems can be considered, and by progressing in the order of multiview, integral, and holographic 3-D systems, we can envision the configuration of a "dream system" far removed from the traditional concept of 2-D systems. Depth information of the 3-D video systems, in general, is converted to 2-D images when recorded and transmitted. Therefore, a drastic improvement of resolution enables the system to carry enough depth information.

The authors discuss practical problems, focusing, and accuracy of lens arrays involved in constructing integral imaging systems. In general, it is recommended to set the focusing for the object during capture to infinity. The positional error of the elemental lens arrangement significantly affects the image quality when the image is reconstructed near the observer. An experimental system in consideration of the practical problems that uses an extremely high resolution video system is described. Some pictures obtained by the system show the specific characteristics of this spatial imaging type of system.

A fundamental element of stereoscopic image production is to geometrically analyze the conversion from real space to stereoscopic images by binocular parallax under various shooting and viewing conditions. This paper reports on this analysis, particularly on the setting of the optical axes of three-dimensional (3-D) cameras, which has received little attention in the past. First, we identified the conditions for setting the optical axes that maintain linearity during the conversion from real space to stereoscopic images. We then clarified, in geometrical terms, the shooting and viewing conditions and also conditions under which the puppet-theater effect and cardboard effect occur. The results showed that the parallel camera configuration, by which optical axes are kept parallel to each other, does not produce the puppet-theater effect as the apparent magnification (lateral magnification) of a shooting target is not dependent on the shooting distance. However, the toed-in camera configuration, where the apparent magnification of a shooting target is dependent on the shooting distance, may produce this effect. The cardboard effect is shown to be likely to occur for both camera configurations by defining this phenomenon by the ratio of depthwise reproduction magnification (depth magnification) and apparent reproduction magnification (lateral magnification). Lastly, the paper reports on the relationship between the results of this analysis and those of subjective evaluation experiments. The results need a closer examination by using many more images.

We equate multi-viewpoint image acquisition with object sampling from different viewpoints, and calculate the resolution of multi-viewpoint camera systems. Aliasing, which occurs with the sampling, leads to depth shifting of objects. For instance, an image of a distant object may be taken as if it were near when aliasing occurs. A condition of the camera pitch free from aliasing is discussed. An appropriate prefilter for the sampling can eliminate alias-causing spatial-frequency components, even when the camera pitch is large. We analyze the characteristics of the prefilters from the aspects of depth shifting, ghosting, and waveform distortion. The experimental results show that a prefilter, which reduces ghosting, can be realized optically. For precise acquisition of multi-viewpoint images, however, a prefilter with electrical processing is needed.

This paper focuses on the scanning methods of a field-sequential stereoscopic display system. We examined the advantages and disadvantages of several scanning methods to identify the most suitable one for the field-sequential stereoscopic display technique. An evaluation test using a system with 525 scanning lines and a 120-Hz field frequency was conducted. The results show that the picture quality of the 4:2 or 4:1 interlace method, which maintains high vertical resolution, is superior to that of the simple 2:1 interlace one. We also developed an experimental field-sequential stereoscopic system for HDTV with 1:2 interlacing and confirmed that it is possible to display high-quality stereoscopic HDTV pictures in full 1125-line vertical resolutions.