## 1 Introduction  
Digital electroholographic display technology has been believed to be an ultimate solution for 3-dimensional displays due to its theoretically perfect 3-dimensional visual cue support without any conflict among them. There has been active research and development of many prototype systems, though most suffer from critical performance limitations such as small image size or narrow viewing angle. We can categorize the realization of electronic dynamic holographic displays into two groups: one is a flat panel-based direct front viewing type and the other is tabletop type which renders volumetric 3D images floating on or above the display. The former type can render extruding 3-dimensional images in front of or behind the display, which is not much different from conventional stereoscopic or multiview 3D displays. Almost all displays, including TVs, PC monitors, information kiosk, and smartphones, are of the former type and it is natural trying to make a 3-dimensonal display of the same type. However, holograms and holographic displays are expected to have more powerful 3D rendering capability with volumetric 3D images looking much like a real object. This expectation is universally depicted in many SF movies including old classic Star Wars or the very recent Avatar. Moreover, current prototype systems of the former type reported so far have a very narrow viewingangle, so that even the basic requirements, such as supporting motion parallax or binocular parallax, are hardly satisfied.  
In the authors' opinion, a tabletop display is the more desirable type of electronic holographic display realization. Tabletop display can show full perspective views of an object or scene from 360 degree around, so that it gives viewers much better perception of the whole shape, volume, and relation among parts of the scene or objects. Miniaturized scene or moving objects on a tabletop display, rendered by holographic principle, will surely give excellent realism that cannot be achieved by front-viewing displays. In this regard, we believe that the tabletop holographic display has much wider application areas.  
We have successfully implemented several versions of tabletop holographic display system with commercially available DMD (Digital Micromirror Device) for SLM (Spatial Light Modulator) device. We have previously reported on the first version of the system, which is monocolor one [1]. We have upgraded the system to a full color version, and the system can, for the first time, render color holographic video, which can be watched by multiple viewers at the same time, freely from 360 degrees around the display. In this article, we report on the enhanced version of the system, which is full-color, full parallax with extended vertical viewing range, and address initial experimental result of performance measurement and evaluation of the system. In Section 2, the prior art of the holographic display implementation is briefly reviewed. In Section 3, the overall design concept and methodologies of the target system are capitulated, followed by implementation details of the enhanced parts and experimental results including the system configuration and rendered images are given in Section 4. In Section 5, we address on the performance evaluation issues including definition of metrics, measurements, and evaluation regarding each metric, followed by conclusions and discussions on further issues.