US 7,394,572 B2
Method and apparatus for processing of half-tone image
Nobuhiko Nakahara, Susono (Japan)
Assigned to Kabushiki Kaisha Toshiba, Tokyo (Japan); and Toshiba Tec Kabushiki Kaisha, Tokyo (Japan)
Filed on Sep. 23, 2004, as Appl. No. 10/947,657.
Prior Publication US 2006/0061825 A1, Mar. 23, 2006
Int. Cl. H04N 1/405 (2006.01)
U.S. Cl. 358—3.2  [358/3.06] 20 Claims
OG exemplary drawing
 
1. An image processing apparatus which converts a continuous gradation image into image data of M (M≧2) values by a 1 to N (N≧1) pseudo half-tone process by the use of a threshold matrix, comprising:
the threshold matrix has a plurality of half-tone centers and lattice elements which are addressable at a rational tangent angle, and each interval between any of the half-tone centers and its closest half-tone center being equal; and
a growth order among half-tones is established by synthesizing micro inhomogeneous components with respect to the threshold matrix of super cells defined in a defined periodic order to set threshold values again.