Facsimile and static presentation processing – Static presentation processing – Attribute control
Reexamination Certificate
1998-02-13
2001-06-19
Rogers, Scott (Department: 2624)
Facsimile and static presentation processing
Static presentation processing
Attribute control
C358S530000, C358S451000, C382S252000
Reexamination Certificate
active
06249354
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image processing apparatus and method, and more particularly to color processing in a monochrome printing mode.
2. Related Background Art
Conventionally, a color printer having inks of C, M, Y and K (cyan, magenta, yellow and black) performs printing using the C, M, Y and K inks in a case where color printing is designated. Further, in a case where monochrome printing is designated, the printing has been performed using only black ink as shown in FIG.
3
.
However, if the printing is performed using only black ink in monochrome printing, there sometimes occurs remarkable graininess in a low-density portion. In this case, image quality is deteriorated as compared with a case where gray data is printed using the color inks. Further, even if the printing is performed using only black ink, sometimes the black subtly becomes reddish or bluish depending on a medium characteristic.
SUMMARY OF THE INVENTION
The present invention has been made in consideration of the above-mentioned problems, and an object thereof is to improve image quality in monochrome printing.
To attain the above-mentioned object, the present invention is characterized by an image processing method having a monochrome printing mode and a color printing mode for reproducing a gray image using a plurality of colors in a case where the monochrome printing mode is set, comprising the steps of:
inputting gray image data;
converting the gray image data into color image data composed of a plurality of color components;
performing a quantization process to the color image data; and
performing an error diffusion process for distributing a quantization error of the color image data to peripheral pixels of an objective pixel in accordance with the direction set for each of color components.
Further, the present invention is characterized by an image processing method having a monochrome printing mode and a color printing mode for reproducing a gray image using a plurality of colors in a case where the monochrome printing mode is set, comprising the steps of:
inputting gray image data;
converting the gray image data into color image data composed of a plurality of color components;
performing a color processing to the color image data; and
forming an image on the basis of the color processed color image data.
Other objects and features of the present invention will become apparent from the following embodiments and the attached drawings.
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patent: 4975786 (1990-12-01), Katayama et al.
patent: 4998165 (1991-03-01), Lindstrom et al.
patent: 5521989 (1996-05-01), Fan et al.
patent: 5534915 (1996-07-01), Sandrew et al.
patent: 5625755 (1997-04-01), Shu et al.
patent: 5708728 (1998-01-01), Nomura et al.
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Rogers Scott
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