US 5,477,346 A · Digital color copying machine for reproducing improved black characters with only black toner

Abstract

A digital color copying machine improves the quality of an image of black characters by reproducing them with only black toner and prevents the edges of each black character from being colored with a color. The machine includes a monochromatic signal generator for generating a monochromatic signal in response to inputted plural color signals and an edge emphasizer for emphasizing edge components of the color signals with a predetermined edge emphasis amount. Either a digitizer for digitizing the monochromatic signal and outputting a binary signal of the monochromatic signal or a pseudo digitizer for generating a pseudo binary signal by steepening the contrast of the monochromatic signal is provided. A first area detector, second area detector, and third area detector are respectively provided for detecting first through third image areas. A first reproducer, second reproducer, and third reproducer are respectively provided for reproducing, in response to the binary signal, the color document image included in the first through third image areas detected by the first through third area detectors. A zoomer may be provided along with the pseudo digitizer, these zoomer performing a zooming process for the edge emphasis image signal with a predetermined zooming ratio such that the pseudo digitizer generates a pseudo binary signal by steepening the contrast of the monochromatic signal with a contrast conversion characteristic determined according to the zooming ratio.

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Drawings

Claims15

Dependent claims

A digital color copying machine comprising:

a monochromatic signal generator, said generator generating a monochromatic signal in response to inputted plural color signals obtained by reading a color document image;
an edge emphasizer, said edge emphasizer emphasizing edge components of said color signals with a predetermined edge emphasis amount, and outputting an edge emphasis image signal;
a digitizer, said digitizer digitizing said monochromatic signal and outputting a binary signal of said monochromatic signal;
a first area detector, said first area detector detecting a first image area comprising an inner area of black characters other than edges of said black characters, said black characters being included in a color document image and said black characters being printed in black in response to said inputted plural color signals;
a second area detector, said second area detector detecting a second image area where there are edges of said black characters of said color document image in response to said inputted plural color signals;
a third area detector, said third area detector detecting a third image area where there are color characters other than said black characters in response to said inputted plural color signals;
a first reproducer, said first reproducer reproducing, in response to said binary signal, said document image included in said first image area detected by said first area detector on a recording medium with only black toner;
a second reproducer, said second reproducer reproducing, in response to said binary signal, said color document image included in said second image area detected by said second area detector on said recording medium with only black toner;
and
a third reproducer, said third reproducer reproducing, in response to said binary signal, said color document image included in said third image area detected by said third area detector on said recording medium with cyan toner, yellow toner, magenta toner and black toner, after emphasizing edge components of said color signals with an edge emphasis amount larger than that of the other areas of said document image by said edge emphasizer.

7 more elements

A digital color copying machine comprising:

a monochromatic signal generator, said generator generating a monochromatic signal in response to inputted plural color signals obtained by reading a color document image;
an edge emphasizer, said edge emphasizer emphasizing edge components of said color signals with a predetermined edge emphasis amount, and outputting an edge emphasis image signal;
a pseudo digitizer, said pseudo digitizer generating a pseudo binary signal by steepening the contrast of said monochromatic signal;
a first area detector, said first area detector detecting a first image area comprising an inner area of black characters other than edges of said black characters, said black characters being included in a color document image and said black characters being printed in black in response to said inputted plural color signals;
a second area detector, said second area detector detecting a second image are where there are edges of said black characters of said color document image in response to said inputted plural color signals;
a third area detector, said third area detector detecting a third image area where there are color characters other than said black characters in response to said inputted plural color signals;
a first reproducer, said first reproducer reproducing, in response to said pseudo-binary signal, said color document image included in said first image area detected by said first area detector on a recording medium with only black toner in response to said pseudo binary signal;
a second reproducer, said second reproducer reproducing, is response to said pseudo-binary signal, said color document image included in said second image area detected by said second area detector on said recording medium with only black toner;
and
a third reproducer, said third reproducer reproducing, in response to said emphasis image signal, said color document image included in said third image area detected by said third area detector on said recording medium with cyan toner, yellow toner, magenta toner and black toner, after emphasizing edge components of said color signals with an edge emphasis amount larger than that of the other areas of said document image by said edge emphasizer.

7 more elements

A digital color copying machine comprising:

a monochromatic signal generator, said generator generating a monochromatic signal in response to inputted plural color signals obtained by reading a color document image;
an edge emphasizer, said edge emphasizer emphasizing edge components of said color signals with a predetermined edge emphasis amount, and outputting an edge emphasis image signal;
a zoomer, said zoomer performing a zooming process for said edge emphasis image signal with a predetermined zooming ratio and outputting a zoomed image signal;
a pseudo digitizer, said pseudo digitizer generating a pseudo binary signal by steepening the contrast of said monochromatic signal with a contrast conversion characteristic determined according to said zooming ratio;
a first area detector, said first area detector detecting a first image area comprising an inner area of black characters other than edges of said black characters, said black characters being included in a color document image and said black characters being printed in black in response to said inputted plural color signals;
a second area detector, said second area detector detecting a second image area where there are edges of said black characters of said color document image in response to said inputted plural color signals;
a third area detector, said third are detector detecting a third image area where there are color characters other than said black characters in response to said inputted plural color signals;
a first reproducer, said first reproducer reproducing, in response to said pseudo binary signal, said color document image included in said first image area detected by said first area detector on a recording medium with only black toner;
a second reproducer, said second reproducer reproducing, in response to said pseudo binary signal, said color document image included in said second image area detected by said second area detector on said recording medium with only black toner;
a third reproducer, said third reproducer reproducing, in response to said zoomed image signal, said color document image included in said third image area detected by said third area detector on said recording medium with cyan toner, yellow toner, magenta toner and black toner, after emphasizing edge components of said color signals with an edge emphasis amount larger than that of the other areas of said document image by said edge emphasizer, and performing said zooming process for said edge emphasis signal by said zoomer.

7 more elements

Dependencies are inferred from the claim text.

Description17,409 words

Summary3,736 words

#1. Field of the Invention

#The present invention relates to an image processing apparatus for performing an edge correction process which is applicable to a digital color copying machine, a color facsimile apparatus, an image filing system, and to a digital copying machine comprising the image processing apparatus therefor. More particularly, the present invention relates to an image processing apparatus for performing an edge correction process for image signals of respective pixels sequentially inputted, such as an edge emphasis process, and a digital copying machine for reproducing an image of a color document on a recording medium after reading the image of the color document and converting the read image into image signals, the digital copying machine comprising the image processing apparatus therefor.

#2. Description of the Related Art

Brief description of the drawings36 figures

#These and other objects and features of the present invention will become clear from the following description taken in conjunction with the preferred embodiment thereof with reference to the accompanying drawings, in which:

#FIG. 1 is a schematic block diagram showing a signal processing section of a conventional digital copying machine;

#FIG. 2 is a schematic diagram showing a method for performing an edge emphasis process which is used in a conventional edge emphasis circuit shown in FIG. 1;

Detailed description12,927 words

#A preferred embodiment according to the present invention will be described below with reference to the attached drawings.

#FIGS. 4a and 4b are schematic block diagrams showing a signal processing section of a digital color copying machine of a preferred embodiment according to the present invention.

#Referring to FIG. 4a, a document is scanned and is illuminated by an illumination lamp (not shown), and light including a document image reflected from the document is incident onto a line type CCD image sensor 21. The CCD image sensor 21 converts the document image including image information into image signals R, G and B of red, green and blue including density information of the document image, and outputs the image signals R, G and B to an amplifier 22. The amplifier 22 amplifies the image signals R, G and B, and-outputs the amplified image signals R', G' and B' to an A/D converter 23. The A/D converter 23 converts the amplified analogue image signals R', G' and B' into digital image signals Rd, Gd and Bd, and outputs them to a shading correction circuit 24. The shading correction circuit 24 performs a shading correction process for substantially reject a shading distortion for the digital image signals Rd, Gd and Bd, and outputs the shading-corrected image signals R", G" and B" to a density converting circuit 25. The density converting circuit 25 converts the digital image signals R", G" and B" represented with a reflectance scale into digital image signals C, M and Y of cyan, magenta and yellow represented with a density scale, and outputs the converted digital image signals C, M and Y to a line memory 26.

Facts

Application

08/334,040Filed 2 Nov 1994 · division

Priority

JP 1-34066629 Dec 1989

Granted

19 Dec 1995

Term ended

19 Dec 2012

Estimated · how

Pre-1995 term; greater of 17 years from grant or 20 years from filing when eligible. Maintenance-fee lapses, terminal disclaimers and statutory extensions have not been checked. The continuity chain may be incomplete; this is not an enforceability determination.

Classification7 codes

H04N 1/4092
Edge or detail enhancement; Noise or error suppression: edge or detail enhancement
G06T 7/12
Segmentation; Edge detection: edge-based segmentation
H04N 1/58
Processing of colour picture signals: edge or detail enhancement; Noise or error suppression, e.g. colour misregistration correction
G06T 2207/10008
Still image; Photographic image: from scanner, fax or copier

Digital color copying machine for reproducing improved black characters with only black toner

Life of this patent

Digital color copying machine for reproducing improved black characters with only black toner

Life of this patent

Life of this patent

Abstract

Drawings

Drawings

Claims15

Description17,409 words

Drawings

Classification7 codes

Life of this patent

Description17,409 words