JIST - Society for Imaging Science and Technology

Kajondecha, Cheng, and Hoshino: Human perception of contour in halftoned density step image
Figure 8. Perception ratio dependence on density difference between 64-52 and an angle of 45°, with a
cycle condition and observation distance of a 1mmand1m,b 4mmand1m,c 1mmand3m,and
d 4mmand3m.
observation distance increases. This is due to the decrease in
dot stimulus relative to the contour signal in HVS. The perception
ratio of halftone images with screen angles of 45°
was found to be higher than that observed when the screen
angle is 0° with a cycle of 1mmat observation distances of
0.5 m and 1m. For illumination, contour perception was
found to improve when illumination was decreased at the
large halftone dot cycle of 3mm.
ACKNOWLEDGMENTS
The authors would like to thank Shigeru Kitakubo of the
Nippon Institute of Technology, Japan, Kazuhisa Yanaka of
Kanagawa Institute of Technology, Japan, and the members
of the Hoshino Laboratory for their kind contributions and
efforts, support, and valuable comments.
REFERENCES
1 P. Kajondecha, H. Cheng, S. Huang, and Y. Hoshino, “Contour
perception of halftoned density step image”, Proc. IS&T’s NIP 22 (IS&T,
Springfield, VA, 2006) pp. 351–355.
2 H. R. Kang, Digital Color Half-toning (SPIE, Bellingham, WA, 1999),
p. 61.
3 J. Dusek and K. Roubik, “Testing of new models of the human visual
system for image quality evaluation”, Proc. IEEE International
Symposium on Signal Processing and its Applications, Vol. 2 (IEEE, Los
Alamitos, CA, 2003) pp. 621–622.
4 S. Kitakubo and Y. Hoshino, “Some characteristics on human visual
sensitivity or spatial frequency of digital halftone images”, Proc. IS&T’s
NIP 21 (IS&T, Springfield, VA, 2005) pp. 118–121.
5 M. Ikeda, Image Processing in Human Vision (Heibonsha, Japan, 1999),
p. 137.
6 D. W. Heeley and B. Timmey, “Meridional anisotropies of orientation
discrimination for sine wave gratings”, Vision Res. 28, 337–344 (1988).
7 F. L. Van Nes and M. A. Bouman, “Spatial modulation transfer in the
human eye”, J. Opt. Soc. Am. 57, 401–406 (1967).
406 J. Imaging Sci. Technol. 515/Sep.-Oct. 2007