JPH0797821B2 - Color image processing device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a color image processing apparatus equipped with a color separation means, which is suitable for application to a simple electrophotographic color copying machine or the like.

BACKGROUND OF THE INVENTION Color image information such as an original is optically read and separated into a plurality of colors such as black, red, and blue, and based on this, an output device such as an electrophotographic color copying machine is used. A color image processing apparatus adapted to record on a recording paper is disclosed in Japanese Patent Laid-Open No.
-147374, JP-A-58-62769 and the like.

FIG. 10 shows a main part of a configuration showing an example thereof.

In the figure, the color image information is color-separated into white and cyan, and each of them is projected onto the image sensors 3 and 4 such as CCD and photoelectrically converted.

The white and cyan color signals are supplied to a subtractor 80, from which the red signal is color separated, and these color signals are respectively AGC.
After the gain is adjusted by the circuits 81, 82 and 83, the image processing circuit 84
In, image processing such as gamma correction is performed. After that, it is binarized in the binarization circuits 85, 86, 87.

The binarized output is reconverted into red and black color signals by the arithmetic circuit 88, and is supplied to the color copying machine as an image signal, whereby a color image is reproduced.

FIG. 11 shows an example in which the image processing and the binarization processing are reversed.

[Problems to be Solved by the Invention] By the way, in such a color image processing apparatus, CC
In the case of separating into a plurality of color signals based on the image pickup signal from D, it is necessary to prepare a mapped table and refer to the data in the table instead of separating the color signals by arithmetic processing as in the past. It is conceivable to separate into a plurality of color signals.

In that case, a ROM storing a plurality of color signal data is used as the color separation means.

Further, various image processings such as resolution correction and color ghost correction are performed based on the separated color signals.

When such image processing is considered, the color signals to be separated are not represented as signals of the colors, but
For example, the color signal may be represented by density data and a code (color code data) indicating the color.

When the color signal is represented by the density data and the color code data, for example, the resolution correction may be performed only on the density data, and the color ghost correction process may be performed on the color code data. This is because there are advantages that the system circuit scale can be reduced, and color and density processing can be processed in parallel.

By the way, when an image is recorded using the density data as described above, since the density data has a 4- to 6-bit structure, the density data itself cannot be supplied to the recording section to perform the developing process. Therefore, it is necessary to once convert into a signal form suitable for image recording. As many signal processing circuits as that are necessary for the number of recording units.

As a result, when applied to a color image processing apparatus such as a color copying machine capable of recording a plurality of colors, there is a drawback that the signal processing circuit system becomes complicated.

Therefore, the present invention proposes a color image processing apparatus in which such a problem is simply solved, and in particular, the structure of a signal processing circuit system for obtaining a signal to be supplied to a recording section is simplified. It is a thing.

[Means for Solving the Problem] The above-mentioned problem is that the original color image signal is processed to separate the one corresponding to one pixel into color data and density data, each of which is composed of a plurality of bits. First image processing means for generating a color image signal, multi-valued processing means for multi-valued processing of the density data and outputting a multi-valued signal, and the multi-valued signal based on the color data. A color image processing device, comprising: an image signal transmitting unit that selectively sends to a corresponding recording unit of a plurality of image recording units.

[Operation] The data output from the color separation circuit 15 described with reference to FIG. 1 is density data and color data (hereinafter referred to as color code data) relating to the image data.

The density data is multivalued by the multivalued circuit 30. For example,
It is converted into a ternary signal indicating white, black and gray.

The multilevel signal corresponds to the recording section in the data selection circuit 50.
100-120 is selected. Color code data is used as the selection signal.

That is, when the blue color code data is input, the multilevel signal is selected from the relationship with the color code data so that the predetermined multilevel signal is supplied to the blue image recording unit 100. Image recording is performed by the recording unit corresponding to the selected multilevel signal.

[Embodiment] Hereinafter, an example of the color image processing apparatus according to the present invention will be described in detail with reference to FIG.

FIG. 1 shows a schematic configuration of a color image processing apparatus 10 according to the present invention.

The color image information (optical image) of the original 1 is separated into two color separated images by the dichroic mirror 2. In this example, the color separation image of red R and the color separation image of cyan Cy are separated. Therefore, the cutoff of the dichroic mirror 2 is
Those with a wavelength of 540-600 nm are used. As a result, the red component becomes transmitted light and the cyan component becomes reflected light. On the contrary, it is clear that the cyan component may be transmitted light.

The color-separated images of red R and cyan Cy are supplied to image reading means such as CCDs 3 and 4, and the image signals of only the red component R and cyan component Cy are output from each.

By supplying the image signals R and Cy to the A / D converters 6 and 7,
It is converted into a digital signal of a predetermined number of bits, 6 bits in this example. Shading correction is performed at the same time as A / D conversion.
Reference numerals 8 and 9 represent a part of the shading correction circuit.

Gate circuit for shading-corrected digital image signals
In 11 and 12, only the signal of the maximum document size width is extracted and supplied to the color separation circuit 15 in the next stage. When the maximum document width to be handled is B4 size, the size signal B4 generated by the timing signal forming means (not shown) of the system is used as the gate signal.

Here, assuming that the shading-corrected digital image signals normalized by the white signal are VR and VC, respectively, these image signals VR and VC are supplied to the color separation circuit 15 and separated into a plurality of color signals. At the same time, gamma correction is performed.

In this example, the case where the color signals are configured to be separated into three color signals of red, blue, and black is illustrated, and thus gamma correction is also performed on each of the color signals.

Each separated color signal is composed of color code data (2-bit data) indicating its color information and its density data (6-bit data).

The color code data also includes color code data indicating a background color and white for a document.

The color-separated image data moves to a color image processing step.

First, it is supplied to the next-stage color ghost correction means 20,
Color ghosts in the main scanning direction (horizontal scanning direction) and the sub-scanning direction (drum rotation direction) are corrected. Reference numeral 21 is a color ghost correction circuit in the main scanning direction, and 22 is a color ghost correction circuit in the sub scanning direction.

This is because undesired color ghosts (color ghosts) are generated particularly in the vicinity of black characters during color separation.

Depending on the configuration of the color separation map, red or blue color appears around the black character at its edge. Image quality is improved by removing color ghosts. The color ghost processing is applicable only to color code data.

Image processing includes resolution correction, partial color conversion processing, enlargement / reduction processing, etc. in addition to color ghost correction, but since these image processing are not directly related to the present invention, a specific example thereof will be omitted.

The ghost-corrected density data is multivalued in the multivalued circuit 30. In the embodiment, since the image can be recorded with three kinds of levels of white, black and gray, the multilevel signal is composed of 2 bits.

The multilevel signal and the color code data are supplied to the data selection circuit 50. The selection circuit 50 is for distributing the multilevel signal to the corresponding blue to black recording units 100 to 120, and the multilevel signal is selected based on the color code data.

The recording units 100 to 120 are exemplified by electrophotographic color copying machines. Therefore, each of the recording units 100 to 120 is provided with a developing device corresponding to a recording color, and the photoconductor drum functioning as an image forming body is commonly used. Image exposure is performed by a laser beam. The details will be described later.

The configuration of each part of the color image processing apparatus thus configured will be described in detail below.

The color separation circuit 15 separates the input image signal into a plurality of color signals. A map as shown in FIG. 2 is prepared for color separation. The color separation map is ROM (bipolar ROM). In this case, a color code (designating red, blue, black, and white) and density information after gamma correction are stored at address destinations given by 6-bit image data VR and VC having a halftone level. . That is, 1 image information = color code + density information.

For example, a pixel with hexadecimal display and a density value of 30 levels (XX011110) is Similarly, blue = 01011110 = 5E black = 00011110 = 1E white = 11011110 = DE For white, either DE or CO may be used.

The above data is stored in each address as shown in FIG.

Since the color code has four colors including red, blue and black including white, it is set to 2 bits, but it is clear that if the number of colors increases, the number of bits may be increased accordingly.

Further, although the density information is also 6 bits here, it is practically sufficient to use 4 bits only for characters. Therefore, it is clear that the number of bits may be changed depending on the target image.

The boundary of color separation as shown in FIG. 2 needs to be determined in consideration of the output fluctuation at the edge portion of the line portion. Otherwise, an unnecessary color called a color ghost, which is a kind of color error, will occur at the edge of a black character or the like.

On the other hand, in practice you want to extract a specific color, or red,
Sometimes you want to extract colors other than blue and black. For these, a color separation map different from this example is prepared, and one is selected from a plurality of color separation maps in accordance with a request. Alternatively, the color separation ROM can be attached and removed,
The required ROM (actually a ROM pack) may be replaced.

Maps for three colors are shown in FIGS. 3A and 3B, and maps for four colors are shown in FIG. 3C. These map data are also the data after gamma correction.

FIG. 4 shows a concrete example of the multi-value quantization circuit 30. The density data supplied to the terminal 31 is supplied to a pair of comparators 32 and 33, and the level is compared with a reference threshold value.

Reference numerals 34 and 35 denote threshold ROMs in which a plurality of types of threshold data corresponding to input images such as line drawings and photographic images are stored. Which kind of threshold data is selected depends on the content of the threshold selection signal supplied from the terminal 38.

A predetermined clock CK is supplied to the terminal 37.

The relationship between the level of the inputted density data and the comparison outputs H1 and H2 of the comparators 32 and 33 is shown in FIG.

The comparison output H2 is directly output as the multilevel signal D (D2) to the output terminal 44.
Be derived to. On the other hand, the comparison output H2
The phase-inverted signal at 41 and the other comparison output H1 are supplied to the AND circuit 42, and the multilevel signal D (D1) thereof is output terminal 43.
Be derived to.

The multilevel signal D1 is a gray level recording drive circuit 101 (seventh
(See the drawing) as a drive control signal.

Similarly, the other multi-valued signal D2 is supplied as a drive control signal to the black level recording drive circuit 107 (FIG. 7).

Now, when the relationship between the input level of the density data and the comparison outputs H1 and H2 is selected as shown in FIG. 5, the multilevel signals D1 and D2 as shown in the figure are obtained at the output terminals 43 and 44. . Therefore, when the density data is white, the laser is not driven by the multilevel signals D1 and D2.

However, at the ash level, only the multilevel signal D1 is
Since it is "1", only the gray recording laser is driven. Similarly, at the black level, only the multilevel signal D2 becomes "1", so that only the black recording laser is driven this time.

The multilevel signal D is supplied to the data selection circuit 50, a specific example of which will be described with reference to FIG.

Multi-valued signal D (2 bits of D1 and D2) supplied to terminal 51
Is supplied to three gate circuits 52 to 54 provided corresponding to the color recording units 100 to 120. The gate circuits 52 to 54 each have two inputs and two outputs and have a negative logic configuration.

Since which recording section 100-120 is supplied with the multi-valued signal D depends on what kind of color data is being supplied, which gate circuit 100-120 is activated by the color code data in the present invention. Whether or not to be selected.

Therefore, each of the gate circuits 52 to 54 has a gate control circuit.
60 to 62 are provided, and the gate control signal is generated by the color code data.

The gate control circuits 60 to 62 to which the color code data input to the terminals 55 and 56 are supplied are configured as logic circuits. In the figure, 63 to 69 are inverters, and 70 to 72 are AND circuits. For example, when black color code data (00) is input, only the gate circuit 52 has a logic circuit that opens its gate. .

Therefore, although the detailed configuration of the gate control circuits 60 to 62 is omitted, in the blue color code data (01), the gate circuit 53
Only the open state. In the red color code data (10), the gate circuit 54 is opened, and in the white color code data (11), all the gate circuits 52 to 54 are controlled to be closed.

An example of the recording unit will be described below.

Since the recording units 100 to 120 have the same configuration, only the recording unit 100 will be described.

FIG. 7 shows an example of the recording unit 100. In this example, a pair of laser drive circuits 101 and 107 are used. The former is for gray level recording and the latter is for black level recording. Therefore, the latter has a larger laser output.

Since the multilevel signal D1 is for gray level recording, it is supplied to the laser drive circuit 101 as its laser modulation signal. It is assumed that the laser is driven when the multilevel signal D1 is "1".

The laser beam modulated by the multilevel signal D1 is guided to the deflecting means 104 using a rotating polygon mirror or the like via the collimator lens 102 and the beam splitter 103. As a result, the laser beam deflects and scans the surface of the photosensitive drum 106 in the arrow direction at a constant speed. This is the main scanning.

The photoconductor drum 106 is rotated at a constant speed in the direction of the arrow to perform sub scanning. Reference numeral 105 is an f-θ lens.

The laser driving circuit 107 is controlled by the other multilevel signal D2, and the laser beam modulated by the black level recording multilevel signal D2 is incident on the beam splitter 103 via the collimator lens 108. It is deflected and scanned through the optical path.

The exposure position relationship is selected so that the laser beam supplied through such an optical scanning system reaches a predetermined position on the peripheral surface of the photosensitive drum 106 which constitutes the color copying machine 150 shown in FIG. It

FIG. 8 shows a developing relationship among the recording units 100 to 120. Chargers 131 to 133 and developing devices 134 to 136 are independently provided, and the laser beam is applied to the peripheral surface after charging. It is designed to reach each one.

It should be noted that the exposure timings of the recording units 110 and 120 are selected so that the recording units 110 and 120 perform the exposure processing with a predetermined delay time. This is because the image exposure positions for the recording units 100 to 120 are different as shown in FIG.

As is well known, the color copying machine 150 is image-wise exposed with a laser beam and then developed using a corresponding developing device. After development, transfer and separation poles 137 are used to print a predetermined recording paper (plain paper) 139. Transcribed on. After that, the paper is fixed by the fixing device 138 and then discharged.

In addition, 140 is a static eliminator and 141 is a cleaning device.

In the above example, as a multilevel signal, three levels (white, gray,
Although black is shown as an example, image recording may be performed at four or more levels. In that case, as shown in FIG. 9, a laser drive circuit 160, a collimator lens 161, and a beam splitter 162 may be added. Instead of such a system, multi-level modulation (for example, pulse width modulation) may be performed with one laser.

As the deflecting means 104, a galvanometer mirror, a quartz crystal deflector or the like can be used instead of the rotary polygon mirror.

[Effects of the Invention] As described above, according to the present invention, even if there are many recording colors, it is necessary to use the circuit system from the color separation circuit 15 to the recording units 100 to 120 for the number of recording colors. Disappears. Therefore, there is a real advantage that the circuit configuration can be greatly simplified.

Further, when a plurality of recording units are provided and a plurality of colors are synchronously recorded, the recording time can be shortened.

[Brief description of drawings]

FIG. 1 is a block diagram of the entire apparatus used for a schematic description of a color image processing apparatus according to the present invention, FIGS. 2 and 3 are explanatory views showing an example of a color separation ROM, and FIG. 4 is a multilevel circuit. System diagram, FIG. 5 is a diagram showing the input / output relationship, FIG. 6 is a system diagram of the data selection circuit, FIGS. 7 and 9 are configuration diagrams of the optical scanning system in the recording section, and FIG. 8 is a color diagram. FIG. 10 and FIG. 11 are configuration diagrams showing an example of a copying machine, and are system diagrams of a conventional processing apparatus. 15 ...... Color separation circuit 20 ...... Color ghost correction means 30 ...... Multi-valued circuit 50 ...... Data selection circuit 100-120 ...... Recording section 150 ...... Color copier

Claims (1)

[Claims] 1. A first image processing means for processing an original color image signal to separate one corresponding to one pixel into color data and density data, and to generate a color image signal composed of a plurality of bits. A multi-valued processing means for multi-valued processing the density data and outputting a multi-valued signal; and recording the multi-valued signal corresponding to one of a plurality of image recording units based on the color data. A color image processing device, comprising: