The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 19, 2001
Filed:
Oct. 26, 1998
Jeffrey L. Trask, Boise, ID (US);
Hewlett-Packard Company, Palo Alto, CA (US);
Abstract
A system provides a halftone image having reduced moire patterns by applying a screen function of the type having a first function exhibiting symmetry about a point and a second function exhibiting symmetry about a line. In a progression of tone levels, such a screen function creates first dots, then lines, then dots. For example, a screen function may include the sum of a first function of the type (1−cos(pi*(x+y))*cos(pi*(y−x))) and a second function being a piecewise linear function of x, where {x,y} is a coordinate location in a unit cell mapped to a halftone cell mapped to the image pixel grid. In other embodiments, a unit cell is defined on the grid by a vector. The vector has a component along an axis of the grid. The component has a noninteger length. Unit cells of the type so defined implement rational tangent angles not possible with conventional halftone cells.