We are conducting studies on the video parameters for Super Hi-Vision (SHV).

■ Psychophysical effects of Super Hi-Vision

　We conducted research on the psychophysical effects of the field of view and pixel density to show that the SHV system is capable of providing a strong sense of being there and realness. In FY2011, we evaluated the preferred viewing distance and the sense of being there and the sense of realness for different spatial resolutions in motion video with an 85-inch SHV full-resolution direct-view LCD (see Section 1.1.3) in a home viewing environment⁽¹⁾. The experiments using video with three levels of spatial resolution (2K:1920x1080, 4K:3840x2160, 8K:7680x4320) showed that the preferred viewing distance did not depend on the resolution or content and ranged from 1.5 to 4 times the screen height, with the most preferred distance being 2.5 times the screen height. Furthermore, the sense of being there and the sense of realness were higher for 8K than for 2K or 4K for viewing distances less than three times the screen height (Figure 1).

Figure 1. Sense of being there and the sense of realness for different video resolutions in relation to viewing distance

■ Frame frequency

　We evaluated motion portrayal improvements in higher frame frequency video systems by displaying HDTV-resolution video with 12 different pieces of content on a 100-inch display⁽²⁾. The results showed that increasing the frame frequency from 60 to 120 Hz improved motion portrayal with a rank of 0.45 (on a five-grade interval scale), which is more significant than the improvement with a rank of 0.23 from 120 Hz to 240 Hz. We also found that the effect of increasing the frame frequency heavily depends on the video content, which we suppose is due to different angular velocities of objects in the video.
　On the basis of this result and past research on motion blur, stroboscopic effects, and flicker, we decided on a frame frequency of 120 Hz for full-spec SHV video.

■ Wide color-gamut camera

　We proposed a wide-gamut system colorimetry that uses RGB primaries equivalent to monochromatic light sources on the spectral locus. In FY2011, we produced a prototype HDTV-resolution camera with a spectral sensitivity close to the ideal spectral sensitivity of the system colorimetry, and we evaluated its color reproduction by using a highly saturated color chart we devised⁽³⁾. We found that the camera has no practical problems with color reproduction even for highly saturated colors.

■ Standardization

　We continued work on standardizing the SHV video format (UHDTV in standardization terminology) at ARIB and ITU-R. We proposed the 120-Hz frame frequency discussed above to ITU-R. The major parameters including this one were subsequently agreed upon and reflected in a preliminary draft new Recommendation.

[References]
(1) Y. Kusakabe, K. Masaoka, I. Kondo, Y. Nishida and M. Sugawara: “Subjective Evaluations of Preferred Viewing Distance and Psychophysical Effects of Extremely High Resolution Images Using Super Hi-Vision 85-inch LCD,” ITE Technical Report, Vol. 36, No. 9, ME2012-62, HI2012-24, AIT2012-24, pp. 245-250 (2012) (in Japanese)
(2) M. Emoto, M. Sugawara, Y. Kusakabe and K. Ohmura: “Improvement in Moving Picture Quality by High Frame Rate Television Systems,” ITE Journal, Vol. 65, No. 8, pp. 1208-1214 (2011) (in Japanese)
(3) K. Masaoka, Y. Nishida, M. Sugawara, S. Kato and A. Saita: “Spectral Sensitivity and Color Reproduction for SHV Wide-gamut Camera,” ITE Technical Report, Vol. 35, No. 45, ME2011-130, AIT2011-84, pp. 83-86 (2011) (in Japanese)