JP2982317B2 - Image processing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading means using a full-color sensor, optically scans a document, performs color separation from image information obtained, recognizes a region from a marker color, and recognizes the region. The present invention relates to an image processing apparatus that edits and processes image data to reproduce a two-color image of a sub-color and a main color.

[0002]

2. Description of the Related Art In recent years, with the digitization of color copiers, several different types of color copiers, such as two-color and full-color, have been provided according to user demands. The conventional two-color copying machine executes two development steps, but the present applicant separately proposes a so-called one-pass two-color copying machine that performs two-color copying in one development step ( For example, Japanese Patent Application No. 1-338597: "Image Recording Apparatus").

FIG. 3 is a block diagram showing the overall configuration of a two-color image forming apparatus of a one-pass two-color system, FIG. 4 is a diagram showing an outline of a scanning unit of a document reading apparatus, and FIG. FIG. 6 is a diagram showing a configuration example of an image output unit of FIG.
FIG. 7 is a diagram showing the configuration of S, and FIG. 7 is a diagram for explaining the image reproduction characteristics of the first developing device and the second developing device.

A one-pass two-color copying machine includes an image reading unit 100, an image processing unit 101, and an image output unit 110, as shown in FIG. The image reading unit 100 optically scans the original to scan B (blue), G (green), and R (red).
The image processing unit 101 performs color separation, editing, and color separation from the BGR color separation signal.
The image output unit 110 performs processing to generate density information D and a color flag CF. The image output unit 110 reproduces two types of image data from the density information D and the color flag CF to produce a visible image. It is. This laser printer is equipped with, for example, a two-color toner developing device consisting of red (sub color) and black (main color), and reproduces an image of all red or all black by selecting one of the developing devices. By operating both developing units, red-black 2
This is to reproduce color images. Therefore, a first exposure unit and a second exposure unit are set with a certain gap on the photoconductor, a scanning unit for forming an image on each exposure unit, a developing unit for red toner and a developing unit for black toner. A container is arranged so that a two-color image of one pass and two colors can be formed.

As shown in FIG. 4, the image reading section 100 has a platen cover 104 provided above a platen 102 on which a document 103 is placed, and a light source 105 and a light guide member 106 including a selfoc lens below the platen cover 104. 1 such as CCD
A scanning unit including a full-color sensor 10 using a three-dimensional image sensor is arranged. In the process in which the scanning unit moves in parallel in the direction indicated by the arrow and optically scans the original 103, the original 10 is scanned based on a cell-based detection signal corresponding to the amount of received light output from the full-color sensor 10.
3, image information in units of a predetermined pixel corresponding to a grayscale image, a diagram, a character, and the like drawn on the image 3 is generated.

The image processing unit 101 separates the image information from the full-color sensor into color separation data (B: blue, G: green, R: red) in predetermined pixel units, and separates the data into 25 pixels.
The density information D and the color information SCF, MCF of six gradations, and the marker color information ARCF designated as a closed loop for marker editing are generated. Then, the density information D and the color information SC
Various corrections and filter processing are performed on F, MCF, and ARCF. Further, based on the marker color information, it is determined whether the read pixel is inside or outside the area surrounded by the marker,
The result is output for each pixel, and the density information D and the color information SCF and MCF are edited and processed such as enlargement, reduction, and color inversion.

The image output unit 110 has a configuration as shown in FIG. In FIG. 5, reference numeral 120 denotes a positively charged photoconductor, 121 denotes a charging corotron for pre-charging the photoconductor 120, 122 denotes a dual beam scanning unit (hereinafter referred to as ROS [Raster Output Scanner]), 12
Reference numeral 3 denotes a first developing device using, for example, a positive-polarity red toner; 124, a second developing device using, for example, a negative-polarity black toner; 125, a pre-transfer treatment corotron for aligning the polarity of a toner image on the photoconductor 120; 126 is the recording sheet 12
7, a transfer corotron for transferring the toner image on the photoconductor 120; 128, a discharge corotron for removing the recording sheet 127 electrostatically attached to the photoconductor 120; and 129, a cleaner for removing residual toner on the photoconductor 120; 130 is an eraser lamp for removing residual charges on the photoconductor 120;
A fixing device 131 fixes a toner image on the recording sheet 127 after the transfer process.

The image reproduction characteristics of the recording image density with respect to the input image density of the first developing unit 123 and the second developing unit 124 are different from each other as shown by Ys and Ym in FIG.

Further, details of the ROS 122 will be described with reference to FIG. 141 is a first color image forming semiconductor laser;
142 is a semiconductor laser for image formation of the second color, 143 is a polygon mirror that reflects the beams Bm from the two lasers 141 and 142 at different angles, 144 is its polygon motor, 145 is an fθ lens, and 146 is the first color. A mirror 147 for guiding the beam Bm from the laser 141 to the first exposure unit E1 located in front of the first developing unit 123 of the photoconductor 120, and 147 is a first developing unit for the photoconductor 120 that outputs the beam Bm from the laser 142 for the second color. The second located after 123
Mirrors 148 and 149 leading to the exposure unit E2 are SOS sensors for detecting the scanning start positions of the first and second color laser beams, respectively.

[0010] The drive control system of the ROS 122 is configured as follows. In FIG. 5, the image processing unit 101 outputs red (first color) and black (second color) multi-tone image data in a state separated into density data D and a color flag CF as described above. And the data distribution circuit 150 includes the image processing unit 10
The image data is divided into two systems of image data Ds and Dm based on the density data D and the color flag CF sent from the image data D1. 1st TRC (Tone Reproduction Controller)
) 151 and the second TRC 152 convert the density levels of the image data Ds and Dm distributed by the data distribution circuit 150 according to the reproduced image density characteristics.
The first screen generator 153 and the second screen generator 154 separately process the respective image data Ds and Dm, and generate image density codes SOs and SCm corresponding to the respective image data.
Stores and outputs the image density code SCs from the first screen generator 153 once, and the gap memory 156 stores the image density code SCm from the second screen generator 154 in the first exposure unit E1 and the second
The data is stored and output for a scanning time corresponding to the gap Gp with the exposure unit E2. The first ROS controller 157 controls the driving of the laser 141 and the polygon motor 144 of the first color, and the second ROS controller 158
Is for driving and controlling the laser 142 of the second color.
The respective laser drivers are 159 and 160. 16
Reference numeral 1 denotes a motor driver of the polygon motor 144.

The first ROS controller 157
Denotes an exposure unit as an image unit, and the second ROS controller 158
Are the lasers 141 so that the non-exposed part is an image part,
142 is controlled.

Next, the basic operation of the laser printer 110 will be described. FIG. 8 is a diagram for explaining the image forming process of the image output unit. First, the density data D and the color flag CF from the image processing unit 101 are output.
Are divided into two systems of image data Ds and Dm by the data distribution circuit 150, and are subjected to data conversion by the TRCs 151 and 152.
3 and 154, two systems of image density codes SCs and SCm
Is converted to Thereafter, the data is transmitted to the first and second ROS controllers 157 and 158 via the FIFO 155 or the gap memory 156.

At this time, first, the first ROS controller 157 drives the laser 141 and the polygon motor 144, and the first exposure unit E1 of the photosensitive member 120 is exposed to the latent image as shown in FIG. An image Z1 is formed. When the latent image Z1 is developed by the first developing device 123 under the first phenomenon bias VB1, a first toner image T1 is formed as shown in FIG.

Thereafter, the second ROS controller 15
8 drives the laser 142, and a latent image Z2 in which a non-exposed portion becomes an image portion as shown in FIG. 8B is formed on the second exposed portion E2 of the photoconductor 120. Then, when the latent image Z2 is developed by the second developing device 144 under the second developing bias VB2, a second toner image T2 is formed as shown in FIG.

The toner images T1 and T2 are made uniform in polarity by a pre-transfer treatment corotron 125, and then transferred to a recording sheet 127 by a transfer corotron 126.
Thereafter, the image is fixed by the fixing device 131.

[0016]

The above-described one-pass two-color image processing apparatus generally has a business in which notes, underlines, marks, and the like are written in red on a black-and-white original including a halftone image such as a halftone dot or a photograph. Often deals with documents. That is,
The image using the sub-color red is a binary image close to a binary such as a character or a line drawing, and has no halftone image such as a halftone dot or a photograph. On the other hand, an image using black of the main color is a mixture of a binary image and a halftone image.

However, the image processing apparatus smoothes the image by performing a smoothing process using a smoothing filter in order to enhance the reproducibility of a smooth halftone image. Due to this smoothing filter, there is a problem that the edge of the density data becomes dull, and that portion is output as a black contour.

FIG. 9 is a diagram for explaining a black outline generated around a red character. In the one-pass two-color image processing apparatus, as described above, density information and color information are generated from color separation data of a document read by a full-color sensor and predetermined processing is performed. , A high priority is set for the marker color and the sub color, and a flag is generated as color information of the main color in an area that is neither the marker color nor the sub color. Therefore, in the relationship between the sub color and the main color, the outside of the sub color flag is the main color flag. Therefore, the red 2
When there is a value image, a sub color flag is generated corresponding to the density data as shown in FIG. 9A, and a main color flag is generated outside the sub color flag. As far as we can see at this stage, the density data is captured in the sub color flag,
Since the value in the density data of the area of the main color flag is almost 0, a black contour does not appear.

However, when the above-described filtering process is performed, the density data is smoothed as shown in FIG. 9B, so that the density data has a constant density outside the sub-color flag. In addition, since this area is the area of the main color flag, a black outline appears outside the red color of the sub color, and there is a problem that the image quality of the sub color is reduced.

SUMMARY OF THE INVENTION The present invention is to solve the above-mentioned problem, and in an image processing apparatus for reproducing a two-color image of a main color and a sub-color, an outline of the main color is not formed outside the sub-color. It is intended to do so.

[0021]

SUMMARY OF THE INVENTION The present invention provides an image processing apparatus for generating a two-color image of a main color and a sub-color, which smoothes the color density of a main color which generates a mixed image of a halftone image. A filter unit for performing a process to output a color density, and outputting a color density without performing a smoothing process on a color density of a sub color for generating a binary image;
An image output unit for outputting a main color image and a sub color image based on the color density output from the filter unit.

[0022]

In the image processing apparatus of the present invention, the color density of the main color for generating the mixed image of the halftone image is subjected to the smoothing process to output the color density, and the color density of the sub-color for generating the binary image is obtained. A filter unit that outputs a color density without performing a smoothing process, and an image output unit that outputs a main color image and a sub-color image based on the color density output from the filter unit. With the arrangement, it is possible to prevent the outline of the black main color from being output outside the red sub-color image, and to prevent the image quality from deteriorating.

[0023]

Embodiments will be described below with reference to the drawings.
FIG. 1 is a diagram showing one embodiment of an image processing apparatus according to the present invention. In FIG. 1, a full-color sensor 10 optically scans a document by a CCD line sensor as described above with reference to FIG. 4, and the sensor interface circuit 4 performs time-sharing from the full-color sensor 10 on a cell-by-cell basis. The read signals sequentially output are separated into color separation data (B: blue, G: green, R: red) in a predetermined pixel unit and are output in parallel.

The color image information generation circuit 5 obtains a hue from each color separation data from the sensor interface circuit 4 and performs color separation, edge erasure of a marker portion, background density conversion of a marker portion, and the like, and performs 256 gradations for each pixel. This generates the density information D and the color information, and the marker color information for specifying the closed loop. As color information, a main color flag MCF corresponding to a main color (eg, black) and a sub color flag SCF corresponding to a sub color (eg, red) are generated.
The marker color information includes a first AR color flag ARCF1 corresponding to the first AR color (for example, red) and a second AR color flag ARC corresponding to the second AR color (for example, blue).
F2 is generated.

The area recognition circuit 7 outputs the marker color information (ARCF1, ARCF1) output from the color image information generation circuit 5.
Based on 2), it is determined whether the read pixel is inside or outside the area surrounded by the marker, and the result is output for each pixel. The information of the judgment result here is
1A showing the inside of the area surrounded by the marker of the first AR color
ARDT1 in the R area, ARDT2 in the second AR area showing the inside of the area surrounded by the marker of the second AR color, AROUT outside the area showing both the first AR area and the second AR area.
There are three types.

The correction / filter circuit 6 includes the density information D and the color information color flag SCF from the color image information generation circuit 5,
Various corrections and filter processing such as edge enhancement and smoothing are performed on the MCF.

The editing / processing circuit 8 performs editing and processing such as enlargement, reduction, color inversion, and the like on the density information D and the color information SCF and MCF that have passed through the correction / filter circuit 6. The determination information ARDT1, ARD from the area recognizing circuit 7 is designated by the area designation from the CPU (not shown).
It has a function of performing predetermined editing and processing only on the specified area based on T2 and AROUT.

The density information D and the color information SCF and MCF, which have been subjected to various processes in the correction / filter circuit 6 and the editing / processing circuit 8 as described above, are supplied to the laser printer for reproducing two colors via the interface circuit 9. And specific image forming equipment such as an image transceiver. The data is sent to a computer and stored in an auxiliary storage device such as a magnetic disk device for use.

The CPU 1 controls the above circuits and sets parameters such as tables. The user interface 2 allows the user to designate the number of output sheets, edit, specify processing, and instruct operations by using a control panel or a display. And so on.

FIG. 2 is a diagram showing the configuration of an embodiment of the filter section. The low-pass filter 12 performs an arithmetic operation on the density data of the target pixel and the surrounding pixels using parameters and performs a smoothing process. It is. The selector 11 selects either the input density data or 0 data as the input data of the low-pass filter 12, and the selector 13 outputs either the output of the low-pass filter 12 or the input density data as the output density data. Is to select. The selection signal of the selectors 11 and 13 is a sub color flag SCF, and the sub color flag SCF
Is OFF, the input of A is selected, and if ON, the input of B is selected.

In the above configuration, the selector 11 has an important meaning. For example, if a bypass circuit including only the selector 13 without the selector 11 is configured, even when the sub-color flag SCF is on, the low-pass filter 1
2, the input density data is input as it is. In this case, the low-pass filter 12 smoothes out the density of the sub-color outside the sub-color where the sub-color flag SCF is turned off. That is, in the low-pass filter 12, the density of the sub-color area is set to 0 so that the density of the sub-color is not reduced at all. Can be removed.

Note that the present invention is not limited to the above-described embodiment, and various modifications are possible. For example, in the above embodiment, only the density data of the main color is passed through the low-pass filter 12, but the low-pass filter 12 is applied to the density data of the main color only when the user selects the photograph mode. May be configured. Further, the configuration may be such that the application or exclusion of the low-pass filter 12 can be selected for the sub-color. Although an apparatus for reproducing a two-color image in which the main color is black and the sub-color is red has been described, an apparatus using other colors may be similarly applied.

[0033]

As is apparent from the above description, according to the present invention, notes, underlines, marks, etc., are written in red sub-color on a black main color original which is often found in ordinary business documents. If you want to reproduce the original
Since the density data of the red sub-color is not passed through the low-pass filter, it is possible to prevent the occurrence of a black outline around the red character. Therefore, in a document in which a red binary image is superimposed on a black document in which a binary image and a halftone image are mixed, the reproducibility can be improved without lowering the image quality.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of an image processing apparatus according to the present invention.

FIG. 2 is a diagram illustrating a configuration of an embodiment of a filter unit.

FIG. 3 is a block diagram illustrating an overall configuration of a two-color image forming apparatus of a one-pass two-color system.

FIG. 4 is a diagram illustrating an outline of a scanning unit of the document reading apparatus.

FIG. 5 is a diagram illustrating a configuration example of an image output unit for one pass and two colors.

FIG. 6 is a diagram illustrating a configuration of a ROS.

FIG. 7 is a diagram for explaining image reproduction characteristics of a first developing device and a second developing device.

FIG. 8 is a diagram for explaining an image forming process of the image output unit.

FIG. 9 is a diagram for explaining a black outline generated around a red character;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... CPU, 2 ... User interface, 4 ... Sensor interface circuit, 5 ... Color image information generation circuit, 6 ... Correction
Filter circuit, 7 area recognition circuit, 8 editing / processing circuit, 9 I / O interface, 10 full color sensor

Claims (1)

(57) [Claims] An image processing apparatus for generating a two-color image of a main color and a sub color, wherein a smoothing process is performed on a color density of a main color for generating a mixed image of a halftone image, and a color density is output. A filter for outputting a color density without performing a smoothing process on a color density of a sub-color for generating a binary image; and a main color image and a sub-color based on the color density output from the filter. An image processing apparatus comprising: an image output unit that outputs a color image.