Xerox Corporation

Xiaoxue Cheng

Robert P Loce

Shen-Ge Wang

Beilei Xu

Gregory W Zack

Characteristics of text or text components or features are considered when selecting halftoning screens. For example, an italic slant angle of text is recognized and used to select or generate a compatible halftone screen oriented at the same angle. A screen frequency may be selected based on a thickness of a text component. Descriptive tags associated with text or text components facilitate screen selection. Tags are assigned based on font descriptions included in a document during authoring. Alternatively, tags are assigned based on the results of document segmentation and character recognition techniques. An image processing system operative to consider characteristics of text or text components when selecting halftone screens includes a text component characteristic recognizer, a halftone screen selector and a halftoner. Optionally a print engine is also included. In a xerographic environment the print engine includes a xerographic printer.

Font characteristic driven halftoning

Moir&#xe9; free color halftoning is achieved through the use of two dot screens and one or two line screens. The line screens may be, for example hybrid line screens. Frequency vectors associated with the screens combine to produce moir&#xe9; frequency vectors representing moir&#xe9; frequencies above or below the visual range. In one embodiment lines screens are used to halftone yellow and black separations and dot screens are used to halftone cyan and magenta separations. The dot screens are oriented at 15 and 75 degrees. The line screens are oriented at 45 and 135 degrees. Selected screens and screen orientations minimize screen interaction with mechanical or optical artifacts of a rendering device, thereby minimizing mechanical and optical moir&#xe9;.

Halftoning using dot and line screens to avoid two and three color moir&#xe9;

The present invention is a method and apparatus for reducing two-color moir&eacute;often found during the rendering of full color images using halftoning techniques, by providing shared screen angles between distinct color separations.

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Webster, NY, United States of America

Xiaoxue Cheng