JPS62293887A - Digital color picture reproducing and processing method and its device - Google Patents

Abstract

PURPOSE:To improve color visibility by situating the dot of a half tone representing pattern in different positions and dispersing the dots of the half tone representing pattern used for recording the third color between the centers of the dots of the half tone representing patterns of the first and the second colors. CONSTITUTION:The center of the dot of the pattern (centers of the dot 1, 2) is shifted by 2 in an X direction and by 2 in a Y direction to set as an M (magenta) half tone representing pattern, the center (threshold data 1, 2) of the dot of the pattern is shifted by six boxes in the X direction and by two boxes in the Y direction to set a C(cyanogen) half tone representing pattern, the center(threshold data 1-4) of the dot of the pattern is shifted by the two boxes in the X direction and by the two boxes in the Y direction to set a Y(magenta) half tone representing pattern and record respective colors by recording density data 16 based thereon. In such a way, when the recording density data is 16, the respective colors are not registered but a small area corresponding to a 8X8 matrix is recorded in all surfaces by the same dot number for the respective colors, so that a clear color recording is obtained.

Description

Detailed Description of the Invention [Technical Field] The present invention relates to color image reproduction processing, and in particular, to color-separating an original image to obtain image data for each color component (one-time data), and converting this into recorded color component a-degree data. Process and record each color component.
With recorded color component density data.

The present invention relates to digital color image reproduction processing for so-called halftone recording, in which a halftone expression pattern is specified and the pattern is recorded.

■Prior Art In one type of conventional halftone image recording, when halftone recording is performed based on digital image data ('a degree data) in which the gradation adjustment amount is O-M-N, MXN pieces of 1 ~M-
The digital image data is compared with each threshold value of the threshold value matrix regularly or randomly distributed in the MXN matrix, and if the digital image data is equal to or higher than the threshold value, A recording information bit is assigned to the position of the threshold value, a non-recording information bit is assigned when the value is less than the threshold value, and 1 is assigned to the bit in the form of a recording/non-recording information bit matrix corresponding to the threshold value matrix.
Allocate the above dots and record.

In advance, the threshold matrix is compared with each of the image data indicating 1 to MN, and the recorded and non-recorded information pit matrices when the image data is 1 to MN are determined as follows.
Create M-N bit matrices, store them in memory, and when reading and recording an image, specify one of the recording and non-recording information pit matrices with the image data obtained by reading the image, and write the bit matrix. There is also a mode in which recording is performed in response to.

In the case of monochrome recording, threshold matrix or M-N
One set of recording and non-recording information matrices is sufficient. For color recording 1 For example, Y (yellow), M (magenta)
In the case of three-color recording of C (cyan) and C (cyan), 1
Through color separation decoding and read signal processing, seven image recording data, M image recording data, and C image recording data assigned to Y, M, and C recording are obtained, and each of these image recording data is subjected to the above-mentioned halftone recording. Do the following.

However, if halftone recording of multiple colors is performed based on the same threshold matrix or the same set of recording and non-recording information pit matrices, moiré etc. will appear in the reproduced color image and the image quality will deteriorate. , there is a problem that the brightness of the colors is lost because the gold colors overlap at the same point.

In order to prevent moiré, etc., conventionally, a threshold matrix or a recording/non-recording information pit matrix is rotated by a predetermined angle, and a screen is set at a predetermined angle for each color, which is different from that of other colors. A threshold matrix having a unique screen angle for each color or a recording/non-recording information pit matrix is used instead of having an angle.

An example thereof is disclosed in Japanese Patent Laid-Open No. 182372/1983.

However, in the conventional method, each color is recorded overlappingly at the same point even in a low-density recording area, resulting in poor improvement in color vividness. In addition, because the number of gradations is small, the halftone expression of the reproduced image is poor, and in order to increase this, it is necessary to increase MXN. The recording area allocated to each of the data indicating the density of the entire predetermined small area of the reproduced image becomes large, and the reproduced image becomes enlarged with respect to the original image. To prevent enlargement, 1 of the original image must be
The facet vt to be read as image data must be set large. This results in coarse image reading, which ultimately impairs the fidelity of the reproduced image. In the end, unless the area of one recording dot is made small, even if the number of one gradation level is set over a wide range, the reproduction quality of the image will not substantially improve. Therefore, conventionally,
The halftone expression pattern (threshold matrix or recording/non-recording information pit matrix) could not be made very large.

In addition, conventionally, the same halftone expression pattern (orthogonal threshold matrix or orthogonal recording/non-recording information pit matrix) is rotated by a predetermined angle for each color, which reduces the degree of freedom in setting the screen angle and reduces the vividness of the color. It was not possible to set a halftone expression pattern (threshold matrix or recording/non-recording information bit matrix) that would improve the image quality. conventionally,
As mentioned above, since the halftone expression pattern is relatively small, there is a problem in that this further limits the degree of freedom.

(1) Purpose of the Invention The first object of the present invention is to improve the color clarity of color image reproduction. A second object of the present invention is to make it possible to express a relatively wide range of gradations without having to set a particularly large small area allocated to one image data for original image reading and recording, and to improve color clarity. The goal is to increase the degree of freedom in setting halftone dots for each color.

■Configuration In order to achieve the above object, the present invention.

The color image is separated into multiple colors, the image density is converted into digital data for each color component, and the digital data is processed into color component S density data; several types of threshold data are applied one-to-one to a predetermined minute area. A halftone expression pattern having a predetermined small area of a plurality of threshold data associated with one of recording bit distribution. Color component recording density data is converted into recording/non-recording bit information using a halftone expression pattern consisting of a set of bit distribution patterns corresponding to the range of recording density data; In digital color image reproduction processing, recording bit information is associated with a minute area of a recording medium, and a predetermined color is recorded in a minute area to which recording information bits of the bit information associated with the minute area are to be allocated; :The halftone expression pattern used for first color recording and second color recording is used to record a predetermined area, and as the recording density increases, the recording information bits change to The recording information bit distribution spreads from a predetermined point of the coordinates, and the predetermined points are at different positions for each color, and the halftone expression pattern used for third color recording has a recording information bit distribution that spreads from the predetermined point. This is a halftone expression pattern for each color, in which a plurality of predetermined points are different from the halftone expression patterns of the first and second color recordings, and one set is associated with each color component.

According to this, as the indicated density increases on the halftone expression pattern, the recording area expands from a different position for each color. The higher the density recording, the less overlapping recording of different colors occurs, and therefore the color clarity is significantly improved. Moreover, since the halftone dots are distributed at multiple points in the third color pattern, the color distribution is finely grained, resulting in smooth color expression. For example, if an 8×8 matrix is used as a halftone expression pattern, yellow (Y), magenta (M), and cyan (
Assuming that recording is performed using method C), if the halftone dot center for each color is set at the center of each of the three divided areas of the 8x8 matrix, when each color is recorded with a density of 64/3 (decimal number) or less, the color It becomes a shape with no weight at all. In this case, the clarity of recorded colors up to density 64/3 is extremely high. M and C each reduce the vividness of the color when mixed with the other, but when mixed with Y, the degree of color vividness is lower.

Therefore, in the present invention, the halftone expression pattern for M and the halftone expression pattern for C have their halftone dots separated from each other, and the halftone expression pattern for Y is the halftone expression pattern for M and C. Assume that it is distributed between points. That is, Y
(This increases the number of halftone dots in the Y halftone pattern and the M
The distance between the halftone dots of and C is shorter than the distance between the halftone dots of M and C). According to this, the deterioration of the vividness of M and C is reduced, and the color reproducibility of the color reproduced image is improved.

In a preferred embodiment of the present invention, the halftone dots are further dispersed into two or more points in the M and C patterns to finer the color dispersion and achieve smooth color expression, and the halftone expression pattern MMP is mainly m x n child matrix patterns CM with m pieces in the scanning direction and n pieces in the sub-scanning direction
It is divided into P1t to CMPmn, and the beginning of the script indicates the position of the child matrix pattern in the MMP in the main scanning direction.
The latter half of the font indicates the position in the sub-scanning direction, and if this is used to obtain the image information for the halftone expression pattern, then the information of the child matrix pattern CMPij of the halftone expression pattern specified by the recording density data lCD1j is obtained as the recording information of the bit distribution for the recording density data lCD1j.

According to this, since a part of the halftone expression pattern is assigned to recording density data, the recording area corresponding to one recorded density data is smaller than the area corresponding to the halftone expression pattern, and therefore the halftone expression pattern is allocated to recording density data. Even if the pattern is enlarged, it is possible to record without making the area of one recording dot particularly small, and in a manner that the reproduced image is not enlarged relative to the original image. Nevertheless, since the halftone expression pattern is large, the gradation range of the recording density data is much larger than the gradation range obtained with the matrix pattern corresponding to the area during recording (the conventional matrix pattern corresponds to this). can be set to a large value. Even in such a setting, the small area of the original image to be associated with the 1'a degree data may be small enough to correspond to the recorded small area. Therefore, a wide range of halftone expressions can be obtained without making the image quality particularly coarse.6For example, if the halftone expression pattern is 8×8 and one part of the 4×4 pattern is used for recording, the IJ degree data is The small reading area to be allocated corresponds to 4 x 4, and the small recording area is also 4
It is compatible with X4, and the gradation range is 0 to 8X8.
The gradation range becomes much wider. However, the resolution (how many pixels are allocated to the small area) does not decrease at all.

In addition, by making the halftone expression pattern thicker, the degree of freedom in setting a predetermined point for each color, that is, the center of the halftone dot, in order to record colors vividly in the halftone expression pattern is greatly increased. Moreover, the area allotted for recording becomes wider without overlapping with other colors. This is because, while the number of recorded colors is a predetermined value, the area (number of pixels) of the halftone expression pattern increases, and the ratio of area of the halftone expression pattern/number of recorded colors increases.

To explain the present invention in more detail, for example.

As shown in FIGS. 11a, 11b, and 11c, when threshold data (1 to 64 in decimal numbers in the figure) is distributed in an 8×8 matrix, recording density data becomes 16
(decimal number), the distribution indicated by diagonal lines in the figure is recorded in a small area corresponding to the 8×8 matrix. No matter which pattern is used, it is possible to set a halftone expression pattern (threshold value data matrix) for each color in such a manner that the four colors do not overlap when the recording density data is 16 or less.

For example, if the halftone center (threshold center 1 and 2) of the pattern shown in FIG. 11b is shifted by 2 in the X direction and by 2 in the Y direction, the M (magenta) halftone expression pattern shown in FIG. 12a is obtained. The halftone center (threshold data 1 and 2) of the pattern shown in Fig. 11b is shifted by 6 squares in the X direction and 2 squares in the Y direction to create the C (cyan) halftone expression pattern shown in Fig. 12b. and move the halftone dot center (threshold data 1, 2.3 and 4) of the pattern shown in FIG. 11c in the X direction 2. 2 in the Y direction. If the Y (magenta) halftone expression pattern shown in Figure 12c is set by shifting the squares of , and each color is recorded with recording density data 16 based on these, the recorded color distribution will be as shown in Figure 12a. become. In this way, when the recording density data for each color is 16, the colors do not overlap, and moreover, the entire small area corresponding to the 8×8 matrix is recorded with the number of dots between each color. When the recording density data of each color is 16 or less, there is no overlap between the colors, resulting in vivid color recording. Note that when the halftone expression pattern (threshold value matrix) of each color is set as shown in FIGS. 12a to 12c, the distance between the halftone dot centers (threshold data 1 and 2) between each pattern is Figure 12a) and pattern C (Figure 12)
Note that it is the largest in Figure b).

Suppose that the pattern shown in FIG. 11a (or its halftone dots shifted by X, Y on the matrix) is assigned to M JTI, and the pattern shown in FIG. 11b (or its halftone dots shifted by X, Y on the matrix) is assigned to M JTI. ) for C, the same pattern (the pattern in Figure 11b and its halftone dots shifted on the matrix) is obtained as described above.
, with the halftone dots shifted (Figures 12a and 12b)
The distance between the halftone dots of M and C becomes shorter than that when the dots are assigned to M and C. Therefore, as described above, it is preferable that M and C are the halftone dots of the same basic pattern (FIG. 11b) that are relatively shifted to the maximum extent.

Using similar logic, the basic pattern shown in FIG. 11a may be transformed into two patterns in which the halftone dots are relatively shifted to the maximum extent, and these patterns may be assigned to M and C patterns, respectively. In this case, the Y pattern is, for example, the one shown in FIG. 12b (with halftone dots between the halftone dots of the M and C patterns).
Use.

Similarly, the pattern for M is shown in FIG. 11c,
The pattern for C is the one in which the halftone dots of the pattern in Figure 1IE are shifted by 2 squares in the X direction and 2 squares in the Y direction, and the pattern for Y is the pattern shown in Figure 1ID. may be shifted or modified so that the halftone dot exists between the halftone dots of the M and C patterns.

FIGS. 13a to 13c show an example of pattern assignment for implementing the present invention when using an 10XIO matrix, and FIGS. 14a to 14c show another example. 1st
In Figures 3a to 13c, diagonal lines indicate areas to which bits indicating recording are assigned when the recording density data is 40. In the example shown in FIGS. 13a to 13c, the screen angle differs by 45 degrees for each color, and the halftone dot pitch is 1/, /
7 different. It can be applied to recording gradation images of 101 or less gradations.

The diagonal lines in Figures 14a to 14c indicate recording density data of 20.
The areas to which recording dots are allocated are shown below. In this example, the M and C patterns are the same pattern with the halftone dots shifted so as to have the maximum phase, and the screen angle is 45 degrees different from these patterns, and the #1 point pitch is 1/7T. A pattern in which the phase is shifted so that the halftone dots are farthest from the M and C halftone dots is set for Y. Even if these are recorded with recording density data of 20 or less, as shown in Fig. 14d, not only will one color not overlap, but there will still be gaps, so depending on the combination of recording degrees for each color, It does not get heavy even at high concentrations.

In any of the above examples, the distance between the centers of the halftone dots of the M and C patterns is longer than the distance between them and the center of the halftone dots of the Y pattern. The halftone dot center of the Y pattern is located between the halftone dot center of the 1M pattern and the halftone dot center of the C pattern, and the number of halftone dot centers of the Y pattern is the same as that of the 1M and C patterns. More than the number of point centers.

When the recording density data of each color is a small value, the colors do not overlap, and M and C do not overlap each other up to relatively high gradations. This results in a vivid color record.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

First, referring to FIG. 1, an original 1 is placed on a platen (contact glass) 2, and fluorescent lamps 31+3 for illuminating the original are placed on a platen (contact glass) 2.
2, the reflected light is illuminated by a movable first mirror 41. The light is reflected by the second mirror 42 and the third mirror 43, passes through the imaging lens 5, and enters the dichroic prism 6, where the light of three wavelengths, red (R) and green (
G) and blue (B). The separated light enters CCDs 7r, 7g, and 7b, which are solid-state imaging devices, respectively. That is, the red light enters the CCD 7r, the green light enters the CCD 7g, and the blue light enters the CCD 7b.

The fluorescent lamp 3++32 and the first mirror 41 are connected to the first carriage 8.
The second mirror 42 and the third mirror 43 are
The second carriage 9 is mounted on the carriage 9 and moves at a speed of 172 times that of the first carriage 8, so that the optical path length from the document 1 to the CCD is kept constant, and when reading the original image, the first and second The carriage is scanned from right to left. The first carriage 8 is connected to a carriage drive wire 12 that is wound around a carriage drive pulley 11 fixed to the shaft of a carriage drive motor 10, and the wire 12 is wound around a movable pulley (not shown) on a second carriage 9. As a result, the first carriage 8 and the second carriage move forward (I image reading scanning) and backward (return) by the forward and reverse rotation of the motor 1o, and the second carriage 9 moves at the speed of 172 of the first carriage 8. Moving.

When the first carriage 8 is at the home position shown in FIG. 1, the first carriage 8 is detected by a home position sensor 39 which is a reflective photosensor. That is, when the first carriage 8 is driven to the right during exposure scanning and leaves the home position, the sensor 39 does not receive light (carriage is not detected), and when the first carriage 8 returns to the home position, the sensor 39 When light is received (carriage detection) and the state changes from non-light receiving to light receiving, the carriage 8 is stopped.

Now referring to FIG. 2, CCD 7 r, 7 g
The output of +7b is analog/digital converted and subjected to necessary processing in the image processing unit 100.

Recorded color information: black (BK), yellow (Y),
The signals are converted into binary signals for magenta (M) and cyan (C) recording activation. Each of the binary signals is sent to a laser driver 112bk.

112y, 112m and 112c, and each laser driver outputs a semiconductor laser 113bk, 113y,
By energizing 113m and 113c, laser light modulated with a recording color signal (binarized signal) is emitted.

Referring again to FIG. 1, the 6 emitted laser beams are reflected by rotating polygon mirrors 13bk, 13y, 13m and 13c, respectively, and are reflected by f-theta lenses 14bk and 14.
)'+14m and 14c, 4th mirror 15bk
.

15y, 15m and 15c and 5th mirror 16bk.

16y, 16m and 16c, polygon mirror surface tilt correction cylindrical lens 1.7bk, 17y.

Through 17I11 and 17c, photosensitive drum 18bk
.

18y, 18m and 18c are imaged and irradiated.

Rotating polygon mirrors 13bk, 13y, 13m and 1
3c is a polygon mirror drive motor 4 lbk, 41y, 4
The motors are fixed to rotating shafts 1m and 41c, and each motor rotates at a constant speed to rotate the polygon mirror at a constant speed.

As the polygon mirror rotates, the laser beam is scanned in a direction perpendicular to the rotation direction (clockwise) of the photoreceptor drum, that is, in a direction along the drum axis.

The laser scanning system of the color recording apparatus is disclosed in detail in Japanese Patent Application No. 60-37213 filed by the same applicant, and the laser scanning system shown in FIG. 1 of the present application is also similar thereto.

The surface of the photoreceptor drum is covered by a charge scorotron 19bk connected to a negative voltage high voltage generator (not shown).
It is uniformly charged by 9y, 19m and 19c. When a laser beam modulated by a recording signal is irradiated onto the uniformly charged surface of the photoreceptor, the electric charge on the surface of the photoreceptor flows to the equipment ground of the drum body and disappears due to a photoconductive phenomenon. Here, the laser is not turned on in areas where the original density is high, and the laser is turned on in areas where the original density is low. As a result, the photoreceptor drums 18bk, 18y,
On the surface of 18m and 18c, the part corresponding to the dark part of the original has a potential of -800V, and the part corresponding to the light density part of the original has a potential of -1100 VPa. An image is formed. These electrostatic latent images are developed by a black developing unit 20bk, a yellow developing unit 20y, a magenta developing unit 20m, and a cyan developing unit 20c, respectively. ,yellow.

Forms magenta and cyan toner images.

The toner in the developing unit is positively charged by stirring, and the developing unit is biased to about -200V by a developing bias generator (not shown), and when the surface potential of the photoreceptor is at a location higher than the developing bias, the original is A toner image corresponding to the image is formed.

On the other hand, the recording paper 267 stored in the transfer paper sheet 1-22
is fed out by the feed operation of the feeding roller 259, and sent to the transfer belt 25 by the registration roller 24 at a predetermined timing. The recording paper placed on the transfer belt 25 is transferred to the photosensitive drum 18bk by the movement of the transfer belt 25.
, 18y, 18m and 18c sequentially, and each photoreceptor drum 18bk, 18y, 1
8m and 18c, black, yellow, magenta, and cyan toner images are sequentially transferred onto the recording paper by the action of a transfer corotron at the lower part of the transfer belt.

The transferred recording paper is then sent to the heat fixing unit 1-36, where the toner is fixed to the recording paper, and the J/B/Saigo 1-36
It is discharged to the ray 37.

On the other hand, residual toner on the surface of the photoreceptor after transfer is removed by cleaner units 2 lbk, 21y, 21m and 21c.

The cleaner unit 21bk that collects black toner and the black developer unisol l-20bk are connected to the toner collection pipe 4.
2, and the black toner collected by the cleaner unit 21bk is collected into the current unit 1-20bk. Note that the black toner is reversely transferred from the recording paper to the photosensitive drum 18y during transfer. The yellow, magenta, and cyan toners collected by the cleaner units 21y, 21m, and 21c are not collected for reuse because they are mixed with toners from the different color developing devices in front of these units.

The transfer belt 25 that conveys the recording paper in the direction from the photoreceptor drums 18bk to 18c includes an idle roller 26° and a drive roller 2.
7. It is stretched between an idle roller 28 and an idle roller 30, and is rotated counterclockwise by a drive roller 27. The drive roller 27 is pivotally connected to the left end of a lever 31 that is pivotally connected to a shaft 32 . A plunger 35 of a mode setting solenoid (not shown) is pivotally attached to the right end of the lever 31. A compression coil spring 34 is disposed between the plunger 35 and the support 32, and this spring 3
4 applies clockwise rotational force to the lever 31.

When the black mode setting solenoid is de-energized (color mode), as shown in FIG. 1, the transfer belt 25 on which the recording paper is placed is the photosensitive drum 44bk, 44y.

It is in contact with 44m and 44c. In this state, when recording paper is placed on the transfer belt 25 and toner images are formed on all drums, six toner images are transferred onto the recording paper as the recording paper moves (color mode). When the black mode setting solenoid is energized (black mode), the compression coil spring 34
The lever 31 rotates counterclockwise against the repulsive force of Become. In this state, the recording paper on the transfer belt 25 only contacts the photosensitive drum 44bk, so only the black toner image is transferred to the recording paper (black mode). Since the recording paper does not come into contact with the photoreceptor drums 44y, 44m, and 44c, the recording paper does not touch the photoreceptor drums 44y, 44m, and 44c.

44n+ and 44c adhered toner (residual toner) does not stick, and yellow, magenta, cyan, etc. stains do not appear at all. In other words, when copying in black mode, copies similar to those produced by a normal monochromatic black copying machine can be obtained.

The console board 300 includes a copy start switch, a color mode/black mode designation switch 302 (immediately after the power is turned on, the switch key is off and the color mode is set;
When the switch is closed twice, the switch key lights up and the black mode is set, and the black mode setting solenoid is energized; when the switch is closed the second time, the switch key goes out and the color mode is set, and the black mode setting solenoid is de-energized.) It is also equipped with other input key switches, character displays, indicator lights, etc.

Next, the operation timing of the main parts of the copying mechanism will be explained. 1st
Almost at the same timing as the start of exposure scanning of the carriage 8, modulation energization of the laser 43bk based on the recording signal is started, and the lasers 43y, 43m and 43c are
Photosensitive drums 44bk to 44y, 44+n and 44
The moving time Ty, Tm of the transfer bell 1-25 for the distance c
The modulation energization is started after a delay of 1 and Tc. Colo L-Lon 29bk for transcription.

29y, 2901 and 29c are the lasers 43
Activation is performed after a delay of a predetermined time (the time required for the laser irradiation position on the photosensitive drum to reach the transfer corotron) from the start of modulation activation of Bk, 43y, 43I11, and 43c.

See Figure 2. The image processing unit 100 is a CCD
The three color image signals read by 7r, 7g and 7b are
The signal is converted into black (BK), yellow (Y), magenta (M), and cyan (C) recording signals necessary for recording. The BK recording signal is supplied as is to the laser driver 112bk, but the Y, M, and C recording signals are each supplied with their respective recorded color gradation data in the buffer memory 108.
y, 108m and 108c, and after a time delay of reading and converting into a recording signal after delay times Ty, Tm and Tc, the laser driver 112y,
112i and 112c. Note that the image processing unit 100 has a CCD 7r as described above in the copying machine mode.
, 7+: and 7b. In the graphics mode, the three-color signals are provided from outside the copying machine through the external interface 117.

Shading correction circuit 10 of image processing unit 100
1 is color gradation data obtained by A/D converting the output signals of CCDs 7r, 7g, and 7b into 8 bits.

The read color gradation data is created by correcting optical illuminance unevenness, sensitivity variations of the internal unit elements of the CCDs 7r, 7g, and 7b, and the like.

The multiplexer 102 is a multiplexer that selectively outputs one of the output gradation data of the correction circuit 101 and the output [3 data] of the interface circuit 117.

The γ correction circuit 103 that receives the output (color gradation data) of the multiplexer 102 not only changes the gradation (input gradation data) according to the characteristics of the photoreceptor, but also changes the gradation arbitrarily using the operation button of the console 300. and further change the input 8-bit data to output 6-bit data. Since the output is 6 bits, data representing one of 64 gradations will be output. Red (R) output from the γ correction circuit 103
), 6-bit three-color gradation data representing each gradation of green (G) and blue (B) is generated by complementary color generation,
The signal is applied to the black separation circuit 104.

Complementary color generation and complementary color generation in the black separation circuit 104 are performed using '?' of each one color read signal. The name is read as 2s color signal, and red (R) gradation data is cyan (C) gradation data, and green (G) gradation data is magenta (M).
The gradation data and blue gradation data (B) are converted (read) into yellow gradation data (Y). C,
The M and YfW tone data are applied as they are to the averaging data compression circuit 105. If all of these gradation data indicate 5 density, it is sufficient to record black.
A digital comparator in the circuit 104 compares each of the C, M and 7 gradation data with reference value data set by a switch for setting a threshold value. Each of the digital comparators compares 8-bit data with each other, and receives data (input data) obtained by adding the upper 2 bits of L level to the 6 bits of gradation data, and compares the 1 bit of the lowest digit and the 1 bit of the higher digit. 3 bits were set to L level, and the 2nd to 4th bits from the lowest were set as reference value data set by the switch for threshold setting.8
It compares with Pi1-data (reference value data), and if the input data is less than or equal to the reference value data, L is given to the Nant gate, and if it exceeds it, II is given to the Nant gate. All comparators on Nant Gate are L.
When a signal of
When a signal of 1 is being applied, II (white) is outputted and applied to the data selector 110. To explain this in more detail, the gradation data input to the comparator is 6-bit data in hexadecimal notation and ranges from 0 to 3FI+. When loaded, L represents black and 11 represents white. Therefore, the 2 bits on the MSIl side (Q6, 7) of the 8-bit input data are input to L, and the gradation data of C, M, and Y are input to the lower 6 bits (00 to 5), respectively. The comparison data side uses a set of rotary dip switches so that the comparison level can be set in 7 steps. Furthermore, since this is a black level setting, if too many white colors are included in black, halftones (gray) can be recorded as black and the resolution can be increased, but on the other hand, color balance problems often occur, which is undesirable. Therefore, I decided to set the 5th and 6th bits in 7 steps up to the intermediate level, and since there is no need to set them too precisely, I set the LS [L side 1]
The bit is set to L, and the set value from the dip switch is input to the middle 3 bits (Pi to 3). Now, if the dip switch setting is 010, the reference value is 00000.
10, and when all the data of C, M, and Y are less than this value, that is, between 0 and 3 in lO base, the comparator outputs and the blank (BK) output becomes L (black). Here, the depth inch for setting is commonly used for comparison judgment of C, M, and Y, but by using three sets, it is possible to set it for each color, and switch for setting the minimum and maximum setting range width of each color. By setting using , it is also possible to output a specific color in a black pattern to M f' with good power.

Averaging data compression circuit 105 of blood image processing unit 100
is 4 bits of gradation data for one image.
This averages the X4 image data and outputs it as 6-viso1 gradation data. In the case of this example, the input image and output image are processed to have the same size! Pusama is the standard,
The input data (values read from the CCD) is A/D converted to 8-bit data and converted to 6-bit data by γ correction, but the output data to the laser driver is laser on/off (1 bit) data. . It is possible to separate densities of 64 gradations using input 6-bit data. Therefore, density data is obtained by averaging the densities of 8×8 pixels of input data. Furthermore, this averaging compresses the data amount and processing speed to 1/64, reducing the data capacity for storage and the cost of the hardware unit.

Next, the masking processing circuit 106 and the UCR processing circuit 1
07 will be explained. The calculation formula for masking processing is generally as follows.

Yi, Mi, Ci: data before masking.

YO, MO, CO: data after masking.

In addition, the general formula for UCR processing is It can be expressed as

Therefore, in this embodiment, a new coefficient is obtained by using these equations and using the product of both coefficients to calculate the following. The coefficient (a) of the above equation that performs both masking processing and UCR processing simultaneously
lt", etc.) are calculated in advance and substituted into the above calculation formula to obtain the calculation values (Yo'
etc.: output of the UCR processing circuit 107) is stored in the ROM in advance.

Therefore, in this embodiment, the masking processing circuit 10
6 and the UCR processing circuit 107 are composed of a set of ROMs, and the data at the address specified by inputs Y, M, and C to the masking processing circuit 106 is input to the UCR processing circuit 10.
Buffer memory 1108yj08,10 as output of 7
8c and the gradation processing circuit 109. Generally speaking, the masking processing circuit 106 corrects the Y, M, and C signals in accordance with the spectral reflection wavelength characteristics of the toner for forming a recorded image, and the UCR processing circuit 107 corrects the This is a correction for color balance in the superposition of images.

Next, the buffer memory 108y of the image processing unit 100
, 108m and 108c will be explained. These simply generate a time delay corresponding to the distance between the photoreceptor drums. The writing timing of each memory is simultaneous, but the reading timing of the memory 108y is synchronized with the modulation activation timing of the laser 43Y.
m is performed in accordance with the modulation activation timing of the laser 43m, and memory 108C is performed in accordance with the modulation activation timing of the laser 43c, which are different from each other. The capacity of each memory is when A3 is the maximum size, 24% of the maximum required amount for an A3 original with a memory of 108y, and 4% with a memory of 108m.
8%, or about 72% for the memory 108c.

For example, set the CCD reading pixel density to 400 dpi (
Dots per inch: 15.75 dots/+n+a), then memory 108y is approximately 87 bytes, memory 1
08m should have a capacity of about 174 bytes, and the memory 108c should have a capacity of about 261 bytes. In this embodiment, since 64 gradations and 6-bit data are handled, the capacities of the memories 108y, 108m and 108c are 87 bytes, 174 bytes and 261 bytes, respectively.

As for the memory address, if we calculate the memory address in units of 6 bits instead of units of bytes (8 bits), memory 108y: 116K x 6 to bino 1, memory 1
08n+: 232K x 6 bits and 1 memory
08c: 348K x 6 bits.

Next, the density pattern processing circuit 1 of the image processing unit 100
09 will be explained. This circuit 109 is Y.

It is a circuit that generates a pattern corresponding to each density from recording density data of M, C, and BK, and II
K gradation processing circuit 10!1lbk, Y gradation processing circuit 10
9y.

M gradation processing circuit 109m and C gradation processing circuit 109c
It consists of

The 6-bit gradation data can represent density information of 64 gradations (65 gradations including 0 to which no pattern is assigned). Ideally, if the dot diameter of one dot could be varied in 64 steps, there would be no need to reduce the resolution, but in laser beam electrophotography, the dot diameter modulation is only stable at about 4 steps at most, and generally the density There are many combinations of pattern method, density pattern method, and beam modulation. Here, a processing method of expressing 64 gradations using an 8×8 matrix is used.

FIG. 3 shows the configuration of the V gradation processing circuit to9y.

The pattern memory 1012 is a ROM, and as shown in FIG. 12c, from a halftone expression pattern (threshold distribution pattern) in which threshold data is distributed in an 8×8 matrix, recording information bits are stored only at the position of 1 of the threshold. If there are many, other threshold positions Riko writes non-recording information bits, density 1 pattern specified by density l... Recording information bits are written at positions that are less than i of the threshold, and other threshold positions are written. A density i pattern specified by density i, in which non-recording information bits are written, and a density 64 pattern in which recording information bits 1- are written in the positions (that is, the entire area) of the threshold value of 64 or less. A total of 64 halftone expression patterns representing recording information bits are written, including 64 density patterns specified by . Note that this Y assignment pattern has halftone dot centers in the portion corresponding to the hatched area shown in FIG. 12c. The squares indicated by diagonal lines in FIG. 12c indicate the positions to which recording information bits are allocated when the density data indicates 16.

Other gradation processing circuits 109m, 109c and 109b
The hardware configuration of circuit k is also the same as that of circuit 103y. However, the halftone pattern data stored in the pattern memory is different. In the pattern memory (not shown) of one circuit 109m, 64 patterns created based on the original pattern shown in FIG. 12a are stored in the circuit 109c. The pattern memory (not shown) contains 64 patterns created based on the original pattern shown in FIG. 12b, and the pattern memory (not shown) for one circuit 109bk contains the original pattern shown in FIG. 11a. 64 patterns created based on are stored.

Next, the halftone processing of - color Y will be explained using the first gradation processing circuit 109y as an example. The processing operations of the other gradation processing circuits are the same. In this embodiment, YlM and C are recorded on the same recording paper in full color recording mode, but BK gradation recording is performed in only one color in black (single color) gradation recording mode.

As already explained, one halftone expression pattern (mother matrix pattern) in one group is specified using the recording density data, and information on child matrix patterns that form a part of the mother matrix pattern is extracted and identified. Image information is obtained in the form assigned to gradation data. According to this, the gradation pattern is updated in units of child matrix patterns, so the resolution is increased, and this allows for example the outline of a face in a photographic image.

The reproducibility of edges such as line drawings is improved. For example, in a contour line of an image, the child matrix pattern corresponding thereto becomes part of the high-density mother matrix pattern, so one contour line clearly appears, and in the low-density area outside the contour line, the child matrix pattern corresponding to that part becomes a part of the high-density mother matrix pattern. Since the pattern becomes part of a low-density mother matrix pattern, a low-density image appears and the contours become clear. Furthermore, since the large (mother) matrix pattern is specified using the recording density data, smoothness is improved in areas where gradations with little variation change little by little. That is, in an area corresponding to one mother matrix pattern of the reproduced image, a number of child matrix patterns are lined up, each of which constitutes a mother matrix pattern corresponding to recording density data.

Since the mother matrix patterns have similar patterns when the expression densities are close to each other, in image parts where the densities are gradually changing, the number of children 71 to 71 that constitute one mother matrix pattern is similar. The reproduced image by the matrix pattern is similar to one specific mother matrix pattern, and the number of gradations in table rS1 is approximately the same as the number of expression gradations represented by the mother matrix pattern. Moreover, as shown in FIGS. 12a to 15c, a unique arbitrary dot center can be set for each color. As described later, m mother matrix patterns MVP are arranged in the main scanning direction and n in the sub-scanning direction.
m x n child matrix patterns CM P
11-CM P11 to CMPmn, the beginning of the foot print indicates the position of the child matrix pattern in the main scanning direction within the mother matrix pattern, and the second half of the foot print indicates the position of the child matrix pattern in the sub-scan direction. Information on the child matrix pattern CMPij of the mother matrix pattern specified by the tone data lCD1j is obtained as image information of the bit distribution for the tone data lCD1j. In other words, the positions of the child matrix patterns for which image information is obtained corresponding to each of the arrays constituting one mother matrix pattern and the number m x n gradation data correspond to the positions of the gradation data in the mother matrix pattern. position. According to this, in an area corresponding to one mother matrix pattern of a reproduced image, information is of each mother matrix pattern corresponding to each gradation data, but the position is a predetermined position that constitutes one mother matrix pattern as a whole. The child matrix pattern of position is m
It becomes a shape where n pieces are lined up. According to this, since mother matrix patterns have similar patterns when their expression densities are close to each other, in image parts where the densities change slowly, the reproduced image using m x n child matrix patterns is The similarity to one specific mother matrix pattern becomes even higher, and the expression N function becomes equal to the number of expression gradations expressed by the mother matrix pattern, making it easier to express density than the conventional fixed density pattern method using the mother matrix pattern. become equivalent.

In addition, for example, in the case of a contour line in an image, the corresponding child matrix pattern becomes part of the high-density mother matrix pattern, so one contour line clearly appears, and in the low-density area outside the contour line, the corresponding child matrix pattern becomes part of the high-density mother matrix pattern, so one contour line appears clearly. Since the child matrix pattern becomes a part of the low-density mother matrix pattern, a low-density image appears and one outline becomes clearer.

The mother matrix pattern of one group has a density of N011~
The 64th floor x (a degree 0
Although it does not have a pattern of It was created based on the mother pattern (Figure 15a).

When the mother matrix pattern is divided into two, A and B shown in FIG. 5a or 5b are child matrix patterns. In the child matrix pattern division shown in FIG.
) and extract its left half A as recorded data,
The mother matrix pattern corresponding to the density is identified as an even-numbered pattern and extracted as the right half Bl recording data.

In the child matrix pattern division shown in FIG. 5b, a density-corresponding mother matrix pattern (one of 64 types) is specified for each of the recording density data in odd-numbered rows, and the upper half A is extracted as recording data. Then, a density-corresponding mother matrix pattern is specified for each of the odd-numbered rows of recording density data, and the lower half B thereof is extracted as recording data.

FIG. 5c shows an example of dividing the mother matrix pattern into four child matrices A-D. In this example, the mother matrix pattern (one of 64 types) is identified using the odd-numbered records in the odd-numbered rows, and the data in the upper left quarter (corresponding to A in Figure 5c) is extracted. Then, the mother matrix pattern (one of 64 types) is created using the even-numbered recording density data of the odd-numbered rows.
, extract the 174 minutes of data in the upper right corner (corresponding to B in Figure 5c), identify the mother matrix pattern (one of 64 types) using the odd-numbered recording density data of the even-numbered rows, and extract the data. Extract the 174 minutes of data at the lower left (corresponding to C in Figure 5C), identify the mother 7 trix pattern (one of 64 types) with the even numbered record data in the even numbered rows, and extract the data at the lower right. 17
Data for 4 minutes (corresponding to D in FIG. 5C) is extracted.

The mother 71-risk pattern is shown in Figure 5d.

When dividing into 16 child matrix patterns A-P,
and 64 child matrix patterns A for the mother matrix pattern as shown in FIG. 5e.

Similarly, when dividing into B, C, etc., the mother matrix pattern is first specified using recording density data, and then the image of the child matrix pattern at the position corresponding to the position where the density data is assigned to the mother matrix pattern is identified. Extract information.

Now, the recording density data shown in FIG. 7a has arrived, and the mother matrix pattern (recorded information bit distribution) is the first one.
Assuming that there are 64 types corresponding to densities 1 to 64 shown in Figure 0, and when 4 divisions are specified, 1 gradation data is.

The reproduced image data has the distribution shown in Fig. 8a (Fig. 8a
The numerical values in the figure correspond to the concentration numerical values in Figure 10.

The alphabets indicate the divided parts in FIG. 5C).

That is, the child matrix patterns are arranged as follows, corresponding to the distribution of incoming recording density data (Fig. 7a).

Note that the number in the first row indicates the mother matrix pattern of the mother matrix pattern I that is assigned to the density indicated by the number.

In the above, the rectangular range surrounded by a is the size of one mother matrix pattern. In Figure 8a.

The rectangular range surrounded by thick lines is the size of one mother matrix pattern. The reproduced image has the form shown in Figure 9a.

When the gradation data is arranged as shown in FIG. 7b,
When image information is reproduced in 16 divisions (as shown in Figure 5d),
This results in a child matrix pattern arrangement as shown in FIG. 8b.

In FIG. 8b, the rectangular range surrounded by thick lines is the size of one mother matrix pattern. In addition, in FIG. 8a, the numbers are of the mother matrix pattern 4.

Refers to the mother matrix pattern assigned to the density indicated by the number. The reproduced image has the form shown in Figure 9b.

Child 7 trix pattern A shown in FIG. 5a, as well as the fifth
The extraction of child matrix patterns A and C shown in figure c is
A 1-byte mask pattern FOH shown in FIG. 4a,
This is performed by performing a logical product with one line of data arranged in the main scanning direction of the mother matrix pattern to be extracted. After taking the logical product, the logical product is stored in the page memory or buffer memory. This is done for 8 lines.

In the mask pattern shown in FIG. 4a, "1" (indicated by diagonal lines in the figure) is stored in the part to be extracted, and "OJ" is stored in the part not to be extracted.

That is, the mask pattern FOH shown in FIG. 4a is F
This is data showing Ol-1.

The child matrix pattern B shown in FIG. 5a and the fifth
The extraction of child matrix patterns B and D shown in figure c is
This is performed by performing a logical product between the 1-byte mask pattern OFH shown in FIG. 4a and 1 line of data arranged in the main scanning direction of the mother matrix pattern to be extracted.

By taking the logical product, the page memory or buffer memory will have
Since "0" in the non-extracted part of the previous logical product memory is stored in memory, read the data in the memory target area of the page memory or buffer memory, perform the logical OR of this and the obtained logical product data, and then The logical sum is updated to the page memory or buffer memory.

This is done for 8 lines. The mask pattern OFH shown in FIG. 4a also has "1" on the part to be extracted.
(indicated by diagonal lines in the figure) is stored in memory, and "0" is stored in areas that are not extracted. The mask pattern OFI (shown in FIG. 4a) is data indicating OFH.

Similarly, when extracting pattern information using the child matrix pattern division shown in FIG. 5d, when extracting child matrix patterns A, E, I, and M, C
Using a mask pattern that is OH, B, F, J and N
For extraction, a yellow mask pattern was used at 3oH,
For extraction of C, G, and Q, a mask pattern of 0C)I was used.

Furthermore, for extraction of H, L, and P, a mask pattern of 03H is used.

Therefore, the data (logical product) extracted from A, E, I, and M is written as is into the page memory or buffer memory, but the data (logical product) extracted from A, E, I, and M, C, and G is written as is into the page memory or buffer memory.

The data extracted from K and O9, H, L, and P (logical product) is logically summed with the data already written in the page memory or buffer memory, and then updated to the page memory or buffer memory. do.

In the child pattern division shown in FIG. 5e, information on child matrix patterns is similarly extracted.

In the above description, the mother matrix pattern is 1 byte in the main scanning direction, in byte units, and the child matrix patterns are all of the same size. Note that the number of bits in the sub-scanning direction of the mother matrix pattern and the child matrix pattern is arbitrary, since it does not matter whether or not they are in units of bye 1 in terms of information processing.

However, in the main scanning direction, it is preferable to first set both the mother matrix pattern and the child matrix pattern in units of bytes because information can be processed in units of bytes at high speed.

Therefore, in the embodiment described above, the child matrix pattern is also processed in byte units by using the mask pattern by the above-mentioned logical processing. Therefore, according to this logical processing, the child matrix patterns constituting one mother matrix pattern do not all have to have the same size. If the mother matrix pattern is in bytes, the child matrix pattern can be easily processed in bytes as described above.

However, when both the mother matrix pattern and the child matrix pattern in the main scanning direction have a fraction of a byte, the process becomes complicated.

Therefore, in such a case, attention is paid to the number of bits C in the main scanning direction of the child matrix pattern.

c X d = e bytes, d and e are the smallest integers,
Then, 1 in the main scanning direction of the child matrix pattern
Column data is written 0 times in a row in the e byte, then logically ANDed with a mask pattern that leaves only the data of one column of the required part in the e byte, and the logical product data is written to the page memory or buffer memory.

When the child matrix pattern is the leftmost one,
In this way, the AND data is written to the page memory or buffer memory as it is, but in the case of a child matrix pattern at a position other than that, it is further logically summed with the data in the page memory or buffer memory and then written to the page memory or buffer memory. Write to memory.

As described above, since a large matrix pattern is used, the advantage is that the number of gradations can be increased.

Since the mother matrix pattern can be easily configured in byte units, there is an advantage that information processing is easy to process in one unit, and since the child matrix pattern is assigned to gradation data, the resolution is high9. Another advantage is that the magnification of the reproduced image can also be changed. For example, one child matrix pattern is assigned to the 11@ tone data, but in the child matrix pattern division shown in FIGS. Therefore, the magnification of the reproduced image is different between the child matrix pattern divisions shown in FIGS. 5a to 5e.

That is, if one piece of gradation data indicates the density of the entire area of 4 dots of one original image (corresponding to the child matrix shown in Figure 5d), then the child matrix pattern division shown in Figure 5d is performed. Then, the reproduced image is 1 compared to the original image.
However, in the child matrix pattern division shown in FIG. 5a, the reproduced image is enlarged twice in the main scanning direction and four times in the sub-scanning direction, and in the child matrix pattern division shown in FIG. 5b, 4 times in the main scanning direction, 2 times in the sub scanning direction
The reproduced image is enlarged twice, and the child's i-
In the matrix pattern division, the reproduced image is enlarged twice in both the main scanning direction and the sub-scanning direction, and in the child matrix pattern division shown in Fig. 5e, the reproduced image is reduced to 172 in both the main scanning direction and the sub-scanning direction. Become.

Therefore, for example, as shown in FIGS. 5c to 5e, a plurality of child matrix pattern divisions are set, and one
By specifying one division mode according to the magnification instruction data M (M indicates the number of divisions), the magnification of the reproduced image can be selected. In order to increase the number of magnifications that can be selected, it is better to increase the size of the mother matrix pattern.

Here, to explain the configuration and operation of the V gradation processing circuit 109y shown in FIG.
This is a ROM that stores 64 kinds of mother matrix patterns created based on the original pattern shown in FIG. 5a, and one of the patterns is specified by the recording density data output from the memory 108y. The data of a specific part (all rows: 8 bits) of the identified pattern is stored in the microprocessor 10.
10, read from memory 1012 and applied to AND gate LG1. and gate LG
1, the microprocessor 1010 gives the aforementioned mask pattern (1 byte). The data of the child matrix pattern is extracted by the logical product processing by Antogame hLG+. The extracted data is given to data selector G3. Selector G3 and or gate LG
2 is for processing the extracted data into a bit distribution corresponding to the recording surface, and by using these and the read/write control of the microprocessor, the extracted data is stored in a buffer memory having a memory capacity of at least one line (8 bit width) or more. The data is expanded.

The data developed in the buffer memory is transferred row by row to the laser driver 112y.

6a and 6b, the microprocessor 101
0 data processing operation is shown. To explain this, the computer 1010 proceeds to gradation data processing to convert the recording density data received from the memory 108y into recording data (data indicating recording dot distribution).

First, read the magnification instruction data M (M indicates the number of divisions of the mother matrix pattern = number of child matrix patterns) and set the number of divisions in the main scanning direction and sub-scanning direction, that is, 5, in the register (Step 1: (The word step is omitted below in parentheses). In this example, 1M is 4
(Figure 5C).

16 (Fig. 5d) or 64 (Fig. 5e). Note that M=16 (child matrix extraction in FIG. 5d) is standard, and the reproduced image is the same size as the original image.

Next, the microprocessor 1010 determines the position of the child matrix pattern to be processed in the sub-scanning direction! Set the counter ■ to 1 to understand (j) N = 1) Step 2)
Counter l for grasping the position (i) in the main scanning direction
Set 1 (i=1) to 1 (step 3), memory 10
Read data from 8y (step 4). If the input data is recording density data, the line counter LC
1 from the contents of counter V to the contents of register B.
Set the value obtained by multiplying by the value obtained by subtracting (8).

Next, the microprocessor 1010 outputs magnification instruction data M
and the contents of counters V and H to identify the mask pattern (
9). That is, from the number of divisions M and the contents of counters V and H, identify the child matrix pattern CMPij from which image data is to be extracted. 5e), and the matrix pattern to be assigned to this child matrix pattern (for example, FIGS. 4a and ah) is specified.

Next, the microprocessor 1010 controls the pattern memory 1
From 012, one byte of data of the line (aligned in the main scanning direction) indicated by the contents of the line counter LC is read out and stored in the buffer memory BUF (internal register). The data is given to the AND gate LGi to perform a logical product, the logical product data is updated to the buffer memory BUF (11), and the contents of the counter 12 are referred to (12).

If the content of counter ■4 is 1, this indicates that the child matrix pattern from which information is extracted is the leftmost one in the mother matrix pattern, so the data in the buffer memory BUF is written as is to the buffer memory 1020. Enter (15).

If the contents of the counter H are not 1, the data of the leftmost child matrix pattern has already been written to the memory 1020, and as a result of this writing, the data of the mask pattern "0" is stored in the other child matrix pattern writing sections. ” is stored in memory, read the LC line (LC is the content of counter LC) (1 byte) of the previously written pattern data from the memory 1020 and store it in the buffer memory MBUF (internal register). Then, the data in the buffer memory MBUF and the data in the buffer memory BUF are given to the OR gate LG2 to take a logical sum, and the logical sum data is updated to the buffer memory BUF.
), data in buffer memory BUF is transferred to page memory 10
20 (15).

Next, the microprocessor 1010 controls the line counter L
C is counted up by 16), line counter LC
and the number of lines of the child matrix pattern 8/V'T
17), if the contents of the line counter LC have not exceeded the number of lines 8/J"W, proceed to image extraction of the next line. More specifically, 18), the contents of counter I■ are compared with the contents of register L (19). If the former is larger than the latter, image extraction ends for the child matrix pattern located at the leftmost end in the main scanning direction within the mother matrix pattern. Therefore, in order to advance the next process to the leftmost child matrix pattern, the contents of the counter H are set to 1 (20), and the process proceeds to the next data reading (4).

When the data read in data reading (4) indicates the end of halftone processing, the microprocessor 1
010 returns to the main routine.

When the data is line feed rLFJ.

21) Counter V is counted up by 1.
The contents of are compared with the contents of register L (22). If the former is larger than the latter, it means that the image processing for the mother matrix pattern has been completed, so set the counter V to 1 and return to 23) Data reading (4). When the data is a carriage return rCRJ, it means that the image processing for the width of the mother matrix pattern in the main scanning direction has been completed, so set the counter 1 to 1 (3) and proceed to data reading (4).

Note that in the above explanation, the original pattern (
12c) is used to form a mother matrix pattern (halftone expression pattern) of 64 types as a -group, and this is stored in the memory 1012 in advance. However, in Memo January 012, The original pattern is stored as a halftone expression pattern, and the recording density data given from the memory 108y is used.

A mother matrix pattern corresponding to the recording density data may be created by comparing each threshold value of the Jfi pattern, or recording and non-recording bit information may be determined by comparing the recording density data with some threshold values of the original pattern. The information may be obtained and recorded based on this information. Alternatively, prior to gradation processing, one group (671 pieces) of mother 71 helix patterns are created by comparing the original pattern with each of the recording density gradation data (1 to 6) indicating 1. , this may be stored in a memory such as a RAM. In this way, the amount of data in the memory 1012 can be reduced.

The gradation processing circuits 109m and 109c have the same hardware configuration and control operation as the gradation processing circuit 109y described above.
and 109bk are respectively magenta M 1 cyan C
and generate black BK recorded image data.

For these, the halftone dot center of the mother matrix (halftone expression pattern) stored in the pattern memory is the 12th
The difference is that the positions are different based on the original patterns shown in FIG. a=12c and FIG. 11a (for BK).

■Effects As explained in detail above, in the present invention, in processing halftone data for each color, halftones used for recording first and second colors, such as M and C, whose color reproducibility deteriorates due to color mixing, expression patterns.

The halftone dots are located at different positions, and the halftone expression pattern used for recording the third color such as Y is placed between the halftone dot centers of the first and second color halftone expression patterns. Since the halftone dots are dispersed, there is no color turbidity in low-density recorded areas, and color reproduction in highlight areas is good.Especially, when many colors are recorded at relatively low density, color clarity is improved. degree will improve.

Since the third color is dispersed as multi-dots in this way, there is a high degree of freedom in setting the halftone expression patterns of the first and second colors so that they do not overlap even at relatively high densities. It is also advantageous against misalignment, and high-quality color prints can be obtained.

Black created by subtractive color mixing is expressed by the overlapping of all colors (1st to 3rd colors), so the halftone dots of the black plate pattern are
By overlapping halftone dots of three colors), effective color expression can be achieved and high-quality multi-gradation color image recording can be achieved.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a mechanical structure according to an embodiment of the present invention. FIG. 2 is a block diagram showing the configuration of the electrical system of this embodiment. FIG. 3 is a block diagram showing the configuration of the gradation processing circuit 109y shown in FIG. 2. FIGS. 4a and 4b are plan views showing mask patterns used for child matrix pattern extraction. Figures 5a, 5b, 5c, 5d and 5e
The figures are plan views showing several ways of dividing a halftone expression pattern into child patterns (partial patterns) A, B, C, . . . in the present invention. 6a and 6b are flowcharts showing the recorded image data processing operation of the microprocessor 1010 shown in FIG. 3. FIG. FIGS. 7a and 7b are plan views showing the distribution of recording density data corresponding to recording surfaces, and the numbers in the figures indicate the density (decimal number) indicated by the recording density data. FIGS. 8a and 8b show recording data extracted from the halftone expression pattern by the divisions shown in FIGS. 5c and 5d, respectively, corresponding to the recording density data distributions shown in FIGS. 7a and 7b, respectively. FIG. 3 is a plan view showing the distribution of recording data when allocated to a recording surface. FIGS. 9a and 9b show the recorded information distribution (
FIG. FIG. 10 is a plan view showing one group of halftone expression patterns created based on original data different from the original data shown in FIGS. 15a to 15d. Figures 11a, 1Lb, 11c, and 1id are plan views showing basic pattern examples of halftone expression patterns used in the present invention, and diagonal lines in the figures indicate 286 degree data of 16. indicates the position to which recording information bits are allocated when . Figures 12a, 12b and 12c are shown in Figure 11b.
FIG. 12d is a plan view showing halftone expression patterns assigned to each recording color based on the basic patterns shown in FIGS. FIG. 3 is a plan view showing the color distribution of a surface recorded based on the pattern of FIG. FIGS. 13a, 13b, and 13c are plan views showing other examples of halftone expression patterns assigned to each recording color. FIGS. 14a, 14b, and 14c are plan views showing still other examples of halftone expression patterns assigned to each recording color, and FIG. 14d is a plan view showing the recording density data of 20 for each color. FIG. 3 is a plan view showing the color distribution of a surface recorded based on these patterns when 1: Document 2 Nibraten 31.32: Fluorescent lamp 41-43: Mirror 5: Variable magnification lens unit 6: Dichroic prism 7r, 7g, 7b: CCD 8: First carriage 9: Second carriage 10: Carriage drive motor 11: Pulley 12: Wire (1 to 12: Color image reading means) 13bk, 13y, 13+++, 13c: Polygon mirror 14
bk, 14y, 14m, 14c: f-0 lens 1
5bk, 15y, 15In, 15c, 16bk
, 16y, 1(on, 16c: Mirror 17bk
, 17y, 17m, 17c Nijilintorical lens 1
8bk, 18y, 18m, 18c: Photosensitive drum 19bk, 10y, 19m, 19c: Charge scorotron 20bk, 20y, 20m, 20
c: Developer 21bk, 21y, 21m, 21c: Cleaner 22: Paper feed cassette 23: Paper feed roller 24 registration roller 25: Transfer belt 26.28.30
: Idle roller 27: Drive roller 29bk, 29y, 29m, 29c: Transfer corotron 31 ni lever 32: Shaft 33: Pin 34: Compression coil spring 35
: Black copy mode setting solenoid plunger 36 : Fixing device 37 : Tray (13-37, 41-46, 112 : Recording means) 39
: Home position sensor 40 : Carriage guide bar 41bk, 41y, 41m, 41c : Polygon mirror drive motor 42 : Toner collection pipe 43bk, 43y, 43m, 43c : Laser 44bk
, 44y, /14m, 44c: Beam sensor 45: Photosensitive drum drive motor 46: Motor driver 100: Image processing unit 104y, 104m, 104c: Digital comparator 10
4sh: Rotary dip switch (101~10
7: Color component data processing means) 109: Gradation processing circuit
109y: 7 gradation processing circuit 109m: M gradation processing circuit 109c: C gradation processing circuit 10bk
: IIK gradation processing circuit 1012 : Pattern memory 1010 : Microprocessor (pattern information reading means) 200 : Microprocessor system 300 : Console

Claims (6)

[Claims] (1) Separating a color image into multiple colors, converting the image density for each color component into digital data, and processing the digital data into color component recording density data; A halftone expression pattern having a plurality of threshold data associated with one of the threshold data for a predetermined small area, or all of the threshold data, is compared with each value of recording density data in a planned range to determine the area corresponding to the predetermined small area. Color component recording density data is converted into recording and non-recording bit information using a halftone expression pattern consisting of a number of sets of bit distribution patterns corresponding to the range of recording density data, with recording and non-recording bit distributions. ;
For each color component, recording and non-recording bit information is associated with a minute area of the recording medium, and a predetermined color is recorded in the minute area to which recording information bits of the bit information associated with the minute area are to be allocated. In digital color image reproduction processing: The halftone expression pattern used for first color recording and second color recording is used to record a predetermined area.
Corresponding to the recording density, as the recording density increases, the recording information bit distribution becomes wider from a predetermined point on the X and Y coordinates, and the predetermined points are at different positions for each color, and the third color The halftone expression pattern used for recording has a recording information bit distribution that spreads from a predetermined point, and a plurality of predetermined points are dispersed between the predetermined points of the first color record and the second color record. A digital color image reproduction processing method, which is different from a halftone expression pattern of two-color recording, and uses a halftone expression pattern for each color, in which one set is associated with each color component. (2) The digital color according to claim (1), wherein a number of minute areas corresponding to a portion of a halftone expression pattern of a set corresponding to a color component is allocated to color component recording density data and recorded. Image reproduction processing method. (3) The halftone expression pattern used for the first color recording and the halftone expression pattern used for the second color recording become substantially the same pattern when many of them are developed into a surface,
The threshold data or recorded and non-recorded data are distributed such that the predetermined point of the first color record and the predetermined point of the second color record are distributed at a maximum distance apart. A digital color image reproduction processing method according to scope item (1). (4) Halftone expression pattern MMP is divided into m×n child matrix patterns CMP_1_1 to CMP_m_n, m in the main scanning direction and n in the sub-scanning direction, and the beginning of the font is the child matrix pattern in MMP. The position of the matrix pattern in the main scanning direction is indicated by the second half of the footnote, and this is expressed as ▲There are mathematical formulas, chemical formulas, tables, etc.▼, and similarly, m× If n pieces of recording density data, ▲mathematical formulas, chemical formulas, tables, etc., are used to obtain image information for one halftone expression pattern, then the child matrix pattern of the halftone expression pattern specified by the recording density data ICD_i_j C
The information of MP_i_j is converted into the recording density data ICD_i_j.
A digital color image reproduction processing method according to claim (1) or (3), wherein recording information of a bit distribution for a digital color image is obtained as recorded information. (5) Color image reading means that separates the color image into multiple colors and converts the image density into digital data for each color component; Color component data processing means that processes the digital data into color component recording density data; When recording a predetermined area using a printer, the recording information bit distribution becomes wider from a predetermined point on the X and Y coordinates as the recording density increases, and the predetermined points are different for each color. The halftone expression pattern of the first color group and the second color recording group located at the position shown in FIG. memory means for storing a midtone expression pattern of a third color recording group, which is different from the halftone expression patterns of the first color recording and the second color recording, distributed between predetermined points; to identify one group, and
pattern information reading means for identifying a set of halftone expression pattern information based on the color component recording density data and reading out information of a predetermined area of the set of halftone expression pattern information from the memory means; and a color component. recording means that associates information in the predetermined area with a predetermined small area of a recording medium and records a predetermined color in a minute area within the predetermined small area to which recording information bits in the information are to be allocated; A digital color image reproduction device comprising; (6) Pattern information reading means: reads halftone expression patterns MMP into m×n child matrix patterns CMP_1_1 to m in the main scanning direction and n in the sub-scanning direction.
CMP_m_n, and the beginning of the footmark indicates the position of the child matrix pattern in the MMP in the main scanning direction, and the second half of the footmark indicates the position of the child matrix pattern in the sub-scanning direction. If it is expressed as ▼ and the image information for one halftone expression pattern is obtained by m×n recording density data ▲ there are mathematical formulas, chemical formulas, tables, etc., similarly consisting of ICD_1_1 to ICD_m_n, then the recording density is The digital color image reproduction processing device according to claim 5, wherein information on a child matrix pattern CMP_i_j of a halftone expression pattern specified by data ICD_i_j is read out as recording information of a bit distribution for the recording density data ICD_i_j.