HANEISHI Hideaki1), OHTAKE Ritsuko1), TSUMURA
Norimichi1), MIYAKE Yoichi1), HUNG Po?Chie2),
ROEHRIG Hans3), DALLAS William J.3)
1) Department of Information and Image Sciences,
Chiba University, 1?33, Yayoi?cho, Inage?ku,
Chiba, 263?8522 Japan
2) R&D Center, Konica Corporation, No.
1 Sakura?machi, Hino, Tokyo, 191 Japan
3) Department of Radiology, The University
of Arizona, Tucson, AZ 85704, USA
Optical Review Vol. 5 No. 3 pp. 163-173(1998).[
Abstract
A method is presented for matching apparent
sharpness between digital image display devices
with different characteristics. The sharpness
is most precisely described by the point
spread function (PSF) as opposed to dot density
such as DPI (dot per inch). The difference
between devices is expressed as difference
between transfer functions obtained from
the PSFs. In the presented method, spatial
frequency filtering for one digital image
is carried out where the ratio of the transfer
functions or its modified version is used
as filter. The modification is introduced
as a clipping operation to reduce excessive
enhancement when the ratio of the transfer
functions has a high pass characteristic
with large gain. Through computer simulation
including a subjective evaluation experiment
and numerical evaluation, the effectiveness
of filtering operation for sharpness matching
is demonstrated.