## 4 Experimental Results  
First, the generation of the virtual images of the subpixels observed through the slit array was confirmed. Figure 4a,b show the captured and magnified images, respectively, where a white image was displayed on the screen. Because the prototype system only had a horizontal parallax, the subpixels were magnified only along the horizontal direction and not in the vertical direction. The horizontally magnified subpixel images were aligned along the slanted cylindrical lenses of the lenticular lens. As shown in Figure 4b, two virtual subpixel images were observed through each slit in the horizontal direction. The widths of the virtual subpixels were measured to have an average value of 0.192 mm. The measured width of the virtual slit image was 0.381 mm. Thus, the average number of subpixels observed through each slit was 1.98. The designed width of the virtual pixel image and slit were 0.194 mm and 0.388 mm, respectively, and the measured and designed values were almost equal. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Title 1** & **Proposed System** & **Previous System** \\ \hline Gap \(g_{p}\) [mm] & 0.799 & 0.883 \\ Pitch of virtual subpixel images \(M_{p}q\) [mm] & 0.194 & 0.413 \\ Number of pixels observed through each lens \(n\) & 2 & 1 \\ Width of slits \(w_{u}\) [mm] & 0.290 & 0.350 \\ Resolution of 3D images & \(1966\times 720\) & \(983\times 720\) \\ Viewing zone angle \(\Phi\) & \(48.0^{\circ}\) & \(43.8^{\circ}\) \\ Light efficiency \(\eta\) & 0.408 & 0.492 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Display parameters of the proposed and previous systems. Figure 4: Generation of virtual images of subpixels: (**a**) captured virtual subpixel images observed through six lenses and (**b**) magnified image for one lens. Figure 3: Prototype of the resolution-improved light-field display using the near-virtual-image mode. Next, the improvement in resolution using the proposed technique was verified by presenting 3D images on the prototype display. The 3D images were generated using computer graphics software (Ubuntu 20.04.6 LTS) by rendering 47 parallax images captured using 47 virtual cameras placed in the viewing zone. The two-dimensional image displayed on the flat-panel display was synthesized by considering a ray emitted from every subpixel and finding the nearest virtual camera from the ray, as explained in the previous paper [7]. In the prototype system, the two times width of the virtual images of subpixels was smaller than the lens pitch, and black regions were present between the adjacent virtual slit images (Figure 4). Thus, the resolution of the parallax images should be larger than 1966 \(\times\) 720 (Table 1). Because the width of the virtual subpixel images and the pitch of the lenses were 0.194 and 0.710 mm, respectively, the resolution of the parallax images increased to 3655 \(\times\) 2056. Figure 5 shows the 3D images generated using the proposed prototype system. These images were captured from the left, center, and right at a distance of 1200 mm from the display using a Canon EOS Kiss X4 (Canon Inc., Tokyo, Japan); the following images were displayed: \"violin\", \"dinosaur\", \"globe\", and \"Unity-chan\". The depths of the \"violin\" and \"dinosaur\", \"globe\", and \"Unity-chan\" ranged from \(-\)40 to 40 mm, from \(-\)100 to 100 mm, and \(-\)20 to 20 mm, respectively. The proposed system has a measured viewing zone angle of 46\({}^{\circ}\). A full-color 3D image could also be displayed by the prototype system. Although we employed the lens array made of acrylic resin, significant chromatic aberrations or off-angle effects of the microlens array were not observed. Figure 6 shows a comparison of the 3D images generated using the proposed and previous systems, as well as the original parallax images of the objects corresponding to certain points of view (ground truth). The specific parts of each 3D image were magnified to confirm image qualities.