Image processing apparatus and image processing method for binary and multivalue halftoning

• US 20100253980A1
• Filed: 06/10/2010
• Published: 10/07/2010
• Est. Priority Date: 03/29/2005
• Status: Active Grant

• Current Assignee: Fuji Xerox Company Limited (Fujifilm Holdings Corporation)
• Original Assignee: Fuji Xerox Company Limited (Fujifilm Holdings Corporation)
• Inventors: Komatsu, Yasuo
• Granted Patent: US 7,999,980 B2
• Time in Patent Office: Days
• US Class Current: 358/3.60
• CPC Class Codes: H04N 1/4051 producing a dispersed dots halftone pattern, the dots having substantially the same size different sizes H04N1/4057

Abstract

An image processing apparatus for converting a multiple gradation image into a binary or multivalue image by use of an area gradation method according to a screen cell is provided. The apparatus includes a receiving unit that receives an input pixel value of each pixel of the multiple gradation image and position information on the screen cell, an output unit that has a lookup table storing an output pixel value corresponding to the input pixel value in such a manner that an image is formed in which the output pixel value is increased or decreased with an increase in the input pixel value, and a screen line number is kept at a prescribed level with the increase in the input pixel value but a dot position is different, and that outputs the output pixel value at a pixel position on the screen cell corresponding to the position information by referring to the lookup table, according to the input pixel value and the position information received by the receiving unit.

Claims

1. An image processing apparatus for converting a multiple gradation image into a binary or multivalue image by use of an area gradation method according to a screen cell,

a receiving unit that receives an input pixel value of each pixel of the multiple gradation image and position information on the screen cell;

and

an output unit that has a lookup table storing an output pixel value corresponding to the input pixel value in such a manner that an image is formed in which the output pixel value is increased or decreased with an increase in the input pixel value, and a screen line number is kept at a prescribed level with the increase in the input pixel value but a dot position is different, and that outputs the output pixel value at a pixel position on the screen cell corresponding to the position information by referring to the lookup table, according to the input pixel value and the position information received by the receiving unit.

2. An image processing method which converts a multiple gradation image into a binary or multivalue image by use of an area gradation method according to a screen cell, comprising:

receiving an input pixel value of each pixel of the multiple gradation image and position information on the screen cell;

storing, in a lookup table, an output pixel value corresponding to the input pixel value in such a manner that an image is formed in which the output pixel value is increased or decreased with an increase in the input pixel value, and a screen line number is kept at a prescribed level with the increase in the input pixel value but a dot position is different; and

outputting the output pixel value at a pixel position on the screen cell corresponding to the position information by referring to the lookup table, according to the received input pixel value and the position information.