Typewriting machines – Including control of format and selection of type-face by... – Including editing or revision system
Reexamination Certificate
2001-03-27
2003-01-07
Vo, Anh T. N. (Department: 2861)
Typewriting machines
Including control of format and selection of type-face by...
Including editing or revision system
C358S448000
Reexamination Certificate
active
06503004
ABSTRACT:
CROSS-REFERENCE TO A RELATED APPLICATION
This application claims priority under 35 U.S.C. §119 to Japanese Patent Application No. 2000-086829 filed on Mar. 27, 2000, the entire contents of which are herein incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to an image processing and forming apparatus such as a painter, a copier, a facsimile, etc., and in particular relates to an image processing and forming apparatus capable of minimizing a dropout in a toner image.
2. Discussion of the Background
As proposed in Japanese Patent Application Laid Open No. 11-127348, a printer that separates an input image signal into character and picture pattern areas and processes image data while giving a priority to resolution in a character area and to gradation in a picture pattern area in order to obtain a high printout reproducibility is well known.
FIG. 23
illustrates such a type of a background printer that includes a scanner &ggr; conversion circuit
101
, an image area separation circuit
102
, a smoothing filter
103
, an edge emphasis filter
104
, a printer &ggr; correction circuit
105
, a gradation circuit
106
, and a write apparatus that employs a laser.
An image signal input through a scanner (not shown) is converted from reflection rate data to brightness data by the scanner y conversion circuit
101
. The input image signal is also input to an image area separation circuit
102
and separated into a character area and a picture pattern area. For example, the image area separation circuit
102
outputs an image area separation signal that has one bit which represents a picture pattern area by “0” and a character area by “1”. The smoothing filter
103
applies weak smoothing to the character area and strong smoothing to the picture pattern area referring to the image separation signal.
Further, the edge emphasis filter
104
emphasizes an edge in the character area and weakens the same in the picture pattern area referring to the image separation signal, thereby emphasizing the edge of the image. The printer y correction circuit
105
raises printer y in the character area and slightly flattens the same in the picture pattern area referring to the image area separation signal, thereby correcting an output value.
The gradation circuit
106
applies a mimetic half tone process such as a dither process, an-error diffusion process, etc., to the picture pattern area referring to the image area separation signal. An output from the gradation circuit
106
is transmitted to the write apparatus
107
via an interface (not shown) thereby controlling a laser device that is provided in the write apparatus
107
. Specifically, the output controls activation of a laser beam that is irradiated from the laser device to a photosensitive section member in a pulse state.
As proposed and well known in Japanese Patent Application Laid Open No. 04-248766, an image area separation circuit
102
includes a possible character area detection device that detects a possible character area (i.e., a character edge area) and a white ground area detection device that detects an area neighboring on a white ground. In addition, the image area separation circuit
102
determines an area that belongs to both of the possible character area and the white ground neighboring area as a character area. According to such an image area separation circuit
102
, an inside of a character having a relatively bolder line such as a gothic typeface typically is determined as a picture pattern area.
FIG. 24
illustrates one example of brightness data that is obtained by the scanner y conversion circuit
101
. Specifically, a brightness change is illustrated along with a scanning direction of an image that has relatively bolder and half tone (about 128/256 gradations) characters and is put on a white ground. In such brightness data, a middle portion of the character, an edge area thereof, and a white ground are determined by the image area separation circuit
102
as a picture pattern area, a character area, and a picture pattern area, respectively.
FIG. 25
is a diagram for illustrating other brightness data, when edge emphasis treatment is applied by the edge emphasis filter
104
in a manner such that an edge portion between a picture pattern area and a character area is selectively emphasized.
Further,
FIG. 26
is a diagram for illustrating still other brightness data when a center of a character is determined by the gradation circuit
106
as a picture pattern area and a line dither pattern having (1×2) pixels is applied thereto. As noted therefrom, a signal in the picture pattern area is converted into multiple high frequency pulses.
In addition,
FIGS. 27 and 28
are diagrams for illustrating both a shape of a laser spot whose ON/OFF is controlled by a signal (i.e., brightness data) of FIG.
26
and an image that is to be reproduced on a print medium. Specifically,
FIG. 27
illustrates a case when a laser ON/OFF operation is controlled per a pixel to align with a left side thereof as a reference. In contrast,
FIG. 28
illustrates a case when a laser ON/OFF operation is controlled per a pixel to align with a right aide thereof as a reference. As understood from these drawings, the laser spot
108
is large and a density of the image reproduced on the print medium is high as a level of the brightness data is high. Thus, an image can be reproduced on a print medium in accordance with an input image signal.
However, according to such an image processing method, since a level of brightness data is lowered by edge emphasis as illustrated in
FIG. 26
, a dropout occasionally appears in an edge portion between a left side character area and a picture pattern area as illustrated in
FIG. 27
when a laser ON/OFF is controlled in a left side alignment. In addition, a dropout occasionally appears in an edge portion between a right side character area and a picture pattern area as illustrated in
FIG. 28
when a laser ON/OFF is controlled in a right side alignment.
To overcome such drawbacks, Japanese Patent Application Laid Open No. 11-127348 includes a character contour area detection device that detects a contour of a character, a background area detection device that detects an area neighboring on a background, and a character inside a high density area detection device that detects a character inside a high density area whose coloring density level exceeds a prescribed level and an whose adjacent area includes uniformity of a coloring density higher than a prescribed level.
Japanese Patent Application Laid Open No. 11-127348 further includes an image separation device that separates and determines images that a character contour and background area and a character inside high density area are determined as character areas, and a remaining area as a picture pattern area. According to such a technology, a dropout can be minimized because the character inside a high density area is determined as a character area, and accordingly, an inside portion of the character is not separated into the character area and the picture pattern area.
As an edge emphasis filter
104
, a Laplace operation edge emphasis filter has widely been known. However, a Laplace operation has disadvantages such as over or under shoot that occurs in a portion other than an edge due to ringing. As a result, an edge generally is excessively emphasized and a dropout appears on a color background or the like, and in particular, when the under shoot occurs, thereby causing remarkable deterioration of an image.
As improvements of such above-described technology, Japanese Patent Application Laid Open Nos. 7-162687 and 8-149305 have been known.
Specifically, Japanese Patent Application Laid Open No. 7-162687 proposes a technology that can remove excessive emphasis that occurs when an edge is emphasized at around an area boundary by controlling an edge emphasis level. Japanese Patent Application Laid Open No. 8-149305 also proposes a technology that can minimize ringing that generally occur
Ricoh & Company, Ltd.
Vo Anh T. N.
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