JP2553045B2 - Digital color image reproduction processing method and apparatus - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a color image reproducing process, and in particular, obtains image data (density data) of each color component by separating an original image.
A so-called halftone recording digital color image reproduction process in which this is processed into recording color component density data, and the recording color component density data specifies the halftone expression pattern for each recording color component and records the pattern. Regarding

2. Description of the Related Art In one type of conventional halftone image recording, when halftone recording is performed based on digital image data (density data) having a gradation range of 0 to MN, M × N of 1 to 1 are recorded. M ・
Each threshold value of threshold data indicating each of N is regularly or randomly dispersed in an M × N matrix, and each threshold value is compared with digital image data. The recording information bit is assigned to the position of the threshold value of, and the non-recording information bit is assigned if it is less than the threshold value, and 1 is assigned to the bit in the form of the recording and non-recording information bit matrix corresponding to the threshold value matrix.
Recording is performed by allocating the above bits.

In advance, the threshold matrix is compared with each of the image data indicating 1 to MN, and MN recording and non-recording information bit matrices are created when the image data is 1 to MN, respectively. Then, this is stored in the memory, and at the time of image reading and recording, one of the recording and non-recording information bit matrix is designated by the image data obtained by the image reading,
There is also a mode in which recording is performed in accordance with the bit matrix.

In the case of monochrome recording, a threshold matrix or M · N
The recorded and non-recorded information matrices may be one set. In the case of color recording, for example, in the case of three-color recording of Y (yellow), M (magenta), and C (cyan), color separation reading and read signal processing are used to allocate to Y, M, and C recording. Y image record data, M image record data and C
Image recording data is obtained, and the above-mentioned halftone recording is performed for each of these image recording data.

However, when halftone recording of a plurality of colors is performed based on the same threshold matrix or the same set of recording and non-recording information bit matrices, moiré and the like appear in a reproduced color image and the image quality deteriorates. There is a problem that the vividness of colors is lost because all colors overlap on the same point.

In order to prevent moire, etc., in the past, a threshold matrix or a recording / non-recording information bit matrix is
It is rotated by a predetermined angle and transformed into one having a predetermined screen angle different from those of other colors, and a threshold matrix having a unique screen angle for each, or recording or non-recording. The recording information bit matrix is used. One example is disclosed in JP-A-58-182372.

However, in the related art, even in a low-density recording area, each color is overlapped and recorded at the same point, so that the improvement in color vividness is poor. Further, since the number of gradations is small, halftone representation of a reproduced image is poor, and in order to increase it, it is necessary to increase M × N. However, if M × N is increased, image data (original image That is, the recording area assigned to each of the data indicating the density of the entire predetermined small area of the reproduced image becomes large, and the reproduced image expands with respect to the original image. In order to prevent enlargement, it is necessary to set a large area to be read as one image data of the original image. This results in rough image reading and eventually impairs the fidelity of the reproduced image. As a result, even if the number of gradations is set to a wide range, the reproduction quality of an image is not substantially improved unless the area of one dot for recording is reduced. Therefore, conventionally, the halftone expression pattern (threshold matrix or recording / non-recording information bit matrix) cannot be made very large.

Further, conventionally, the same halftone expression pattern (orthogonal threshold matrix or orthogonal recording or non-recording information bit matrix) is rotated by a predetermined angle for each color, so that the degree of freedom in setting the screen angle is low and the vividness of the color is low. It was not possible to set a halftone expression pattern (threshold matrix or recording / non-recording information bit matrix) for improving the. Conventionally, since the halftone expression pattern is relatively small as described above, there is a problem that this further limits the degree of freedom.

It is an object of the present invention to simultaneously realize sharpness of recorded colors for color image reproduction, fineness of color dispersion and a wide gradation range, and smoothness of gradation expression.

Structure The present invention separates a color image into a plurality of colors, converts the image density into digital data for each color component, and processes the digital data into color component recording density data; Halftone expression pattern having a plurality of threshold data corresponding to one of the threshold data of a predetermined number of dots, or all of the threshold data is compared with each value of the recording density data in the planned range, and the predetermined number of dots is supported. The color component recording density data is converted into recording and non-recording bit information using a halftone expression pattern consisting of a number of bit distribution patterns corresponding to the range of recording density data, which is the recording and non-recording bit distribution. Recording / non-recording bit information is associated with one dot of the recording medium for each color component, and a predetermined color is recorded in the dot associated with the recording information bit; in digital color image reproduction processing: The halftone expression pattern used at least for the first color recording and the second color recording is used to record a predetermined area, and when the recording density corresponds to the recording density, the recording information bits are located at the X and Y coordinates. The recording information bit distribution spreads from a fixed point, and the predetermined points are different positions for each color and are a plurality of points dispersed for each color.
When the color component recording density data is converted into recording and non-recording bit information, a halftone expression pattern for each color, in which one set is associated with each color component, and is specified by the color component recording density data Based on the coordinates of the pixels of the original image from which the color component recording density data has been obtained from the tone expression pattern, a plurality of dots of a portion of the halftone expression pattern is regularly used as a child matrix pattern corresponding to the pixels of the original pixel. Recording and non-recording bit information obtained from the child matrix pattern are output as image information corresponding to the color component recording density data.

According to this, as the designated density becomes higher on the halftone expression pattern, the recording area spreads from a different position for each color, that is, since the halftone dot center is different for each color, the low As the density recording is performed, there is no overlapping recording of different colors, and thus the color definition is remarkably improved. Moreover,
In the pattern of the same color, the halftone dots are dispersed in a plurality of dots, so that the color distribution is fine and the color expression is smooth. For example, assuming that an 8 × 8 matrix is a halftone expression pattern and recording is performed in yellow (Y), magenta (M), cyan (C) and black (BK),
If the center of the halftone dot is set to the center of each of the four-divided areas of the 8 × 8 matrix for each color, the color will not have any weight when the density is 16 (decimal) or less. In this case, the sharpness of recorded colors up to a density of 16 is extremely high. In the present invention, instead of allocating one color to one area of four divisions in this manner, each color is dispersed into a plurality of points in a form in which the small area of the four divisions is further subdivided. Smooth color expression.

On the other hand, M × N matrix halftone expression pattern is M ×
Since N gradations can be expressed, the larger the halftone expression pattern, the wider the range of gradations can be expressed, the wider the range of gradations that can be expressed, and the larger the number of halftone dots, the higher the degree of sharpness and color dispersion. Although the texture can be made finer, the larger the size of the halftone expression pattern, the larger the area unit for halftone expression (recording area for pattern size: small area). From this aspect, halftone expression is possible. Smoothness is reduced.
That is, the sharpness of the recorded color, the fineness of the color dispersion, and the gradation range are in conflict with the smoothness of gradation expression in size units of the halftone expression pattern.

However, according to the present invention, from the halftone expression pattern specified by the color component recording density data, based on the coordinates of the pixels of the original image from which the color component recording density data is obtained, a plurality of dots of a part of the halftone expression pattern Since the area is regularly cut out as a child matrix pattern corresponding to the pixels of the original image, the smoothness of halftone expression is not impaired, and the sharpness of recorded colors, the fineness of color dispersion and a wide gradation range, and gradation expression are achieved. The smoothness of is realized at the same time.

More specifically, in the present invention, in the present invention, there are m halftone expression patterns MMP in the main scanning direction and n in the sub scanning direction.
, The child matrix patterns CMP _{11 to} CMP _mn are divided into m × n, the head of the character is the position of the child matrix pattern in the main scanning direction within the MMP, and the latter half of the character is the position in the sub-scanning direction. , And this And m × n pieces of recording density data, which similarly consist of ICD ₁₁ to ICD _mn If the image information for one intermediate-floor expression pattern is to be obtained, the information of the child matrix pattern CMPij of the halftone expression pattern specified by the recording density data ICDij is obtained as the recording information of the bit distribution for the recording density data ICDij. .

As described above, since a part of the halftone expression pattern MMP is assigned to the print density data, the printing area corresponding to one print density data is smaller than the area corresponding to the halftone expression pattern MMP. Even if the pattern MMP is increased, it is possible to perform gradation recording with high smoothness without reducing the area of one recording dot.
Nevertheless, since the halftone expression pattern MMP is large, the gradation range of the recording density data is realized by the matrix pattern corresponding to the recording area corresponding to one recording density data (the conventional matrix pattern corresponds to this). It can be set to be much larger than the possible gradation range. Therefore, a wide halftone expression can be obtained without making the image quality particularly rough. For example, when the halftone expression pattern is 8 × 8 and a part of 4 × 4 is used for recording, the reading small area to which 1 density data is assigned corresponds to 4 × 4, and the recording area for 1 density data is recorded. Also corresponds to 4 × 4, and the gradation range becomes 0 to 8 × 8, and the gradation range is remarkably wide, but the switching unit of the matrix pattern is not a wide area unit of 8 × 8, but 4 × 8. It is a unit of 4 and the resolution does not decrease. That is, the smoothness of gradation expression is not impaired.

In addition to this, as the halftone expression pattern becomes larger, the degree of freedom in setting the predetermined point for each color, that is, the center of the halftone dot, for vividly recording the color in the halftone expression pattern becomes significantly higher. Moreover, since it does not overlap with other colors, the area allocated for recording becomes wider. This is because the number of recording colors is a predetermined value, but the area (number of pixels) of the halftone expression pattern increases, and the area of the halftone expression pattern / the number of recording colors increases.

The present invention will be described in more detail.
As shown in FIGS. a, 11b, and 11c, when the threshold data (1 to 64 shown in decimal in the figure) is distributed in the 8 × 8 matrix, the recording density data shows 16 (decimal). If it is a thing, the record of the distribution shown by the diagonal lines in the figure is
It is recorded in a small area corresponding to 8 matrices. Whichever pattern is used, the halftone expression pattern (threshold data matrix) for each color can be set so that the four colors do not overlap when the recording density data is 16 or less.

For example, the pattern itself shown in FIG. 11a is set as the Y (yellow) halftone expression pattern shown in FIG. 12a, and the halftone dot center (threshold data 1
And 2) are shifted by 0 in the X direction and 4 in the Y direction to set the BK (black) halftone expression pattern shown in FIG. 12b, and the halftone dot center (threshold data 1 of the pattern shown in FIG. 11a is set. And 2) are shifted by 2 meshes in the X direction and 3 in the Y direction to set the M (magenta) halftone expression pattern shown in FIG. 12c, and the dot center (threshold value of the pattern shown in FIG. 11a is set. Data 1 and 2) 6 in the X direction, 3 in the Y direction,
When the C (cyan) halftone expression pattern shown in FIG. 12d is set by shifting the squares, and each color is recorded with the recording density data 16 based on these, the recording color distribution becomes the 12th.
As shown in Figure e. In Fig. 12e, squares marked with 0 are areas recorded with Y, squares marked with 1 are areas recorded with BK, squares marked with 2 are areas recorded with M, and 3 are marked. The squares marked with are the areas recorded in C, respectively. As described above, when the recording density data of each color is 16, the respective colors do not overlap each other, and moreover, the entire small area corresponding to the 8 × 8 matrix is recorded with the same number of dots for each color, and the entire surface is recorded. When the recording density data for each color is 16 or less,
Therefore, since there is no overlap between the colors, vivid color recording is achieved. When a halftone expression pattern (threshold matrix) of each color is set as shown in FIGS. 12a to 12d, the distance between the halftone dot centers (threshold data 1 and 2) between the patterns is the M pattern (third pattern). 12c) and C pattern (Fig. 12d)
Note that it is the largest of the two.

For example, the pattern itself shown in FIG. 11b is set as the Y (yellow) halftone expression pattern shown in FIG. 13a, and the halftone dot center of the pattern shown in FIG. 11b (threshold data 1,
2, 3 and 4) are shifted by 2 in the X direction and 2 in the Y direction to set the BK (black) halftone expression pattern shown in FIG. 13b, and the halftone dot center of the pattern shown in FIG. 11b is set. The M (magenta) halftone expression pattern shown in FIG. 13c is set by shifting the grid by 0 in the X direction and 2 in the Y direction, and
The halftone dot center of the pattern shown in FIG. 11b is shifted by 2 grids in the X direction and 0 in the Y direction to set the C (cyan) halftone expression pattern shown in FIG. 13d. When each color is recorded at 16, the recorded color distribution is as shown in FIG. 13e. In Fig. 13e, squares marked with 0 are areas recorded with Y, and squares marked with 1 are BK.
The squares marked with 2, the squares marked with 2 are the areas recorded with M, and the squares marked with 3 are the areas recorded with C, respectively. In this way, the recording density data for each color is 16
In this case, the colors do not overlap, and the entire small area corresponding to the 8 × 8 matrix is printed with the same number of dots for each color, and the entire surface is recorded. When the recording density data for each color is 16 or less, therefore, there is no overlap between the colors, and vivid color recording is achieved. When the halftone expression pattern (threshold matrix) of each color is set as shown in FIGS. 13a to 13d, the distance between the halftone dot centers (threshold data 1, 2, 3 and 4) between the patterns is Note the maximum between the M pattern (Figure 13c) and the C pattern (Figure 13d).

For example, the pattern itself shown in FIG. 11c is set as the Y (yellow) halftone expression pattern shown in FIG. 14a, and the halftone dot center (threshold value data 1 of the pattern shown in FIG. 11c is set.
~ 8) is shifted in the X direction by 5 and in the Y direction by 5 squares, and
The BK (black) halftone expression pattern shown in FIG. 14b is set, and the halftone dot center of the pattern shown in FIG. 11c is set to 7 in the X direction.
The M (magenta) halftone expression pattern shown in FIG. 14c is set by shifting by 5 squares in the Y direction, and the halftone dot center of the pattern shown in FIG. 11c is 6 in the X direction and 0 in the Y direction. The C (cyan) halftone expression pattern shown in FIG. 14d is set by shifting the squares of the
When recording each color with 16, the recorded color distribution is 14e
As shown in the figure. In Fig. 12e, squares marked with 0 are areas recorded with Y, squares marked with 1 are areas recorded with BK, squares marked with 2 are areas recorded with M, and 3 are marked. The squares marked with are the areas recorded in C, respectively. As described above, when the recording density data of each color is 16, the respective colors do not overlap, and moreover, the entire small area corresponding to the 8 × 8 matrix has the same number of dots for each color, and the entire surface is recorded. When the recording density data for each color is 16 or less, therefore, there is no overlap between the colors, and vivid color recording is achieved. When a halftone expression pattern (threshold matrix) of each color is set as shown in FIGS. 14a to 14d, the distance between the halftone dot centers (threshold data 1 to 1 as a representative) between the patterns is M. Note the maximum between the pattern (Figure 14c) and the C pattern (Figure 14d).

Distance using Y, M, C and BK (even if BK is not used,
The following matters are the same for Y, M and C),
Mixed color of M and C causes deterioration of reproduced color. Mixing Y with M and / or C has a low degree of deterioration in reproduced color. For the color mixture of BK, that part becomes BK. Since that part of the original image is originally black, the color mixture of BK is therefore not a problem, but if BK is recorded in a shadow area where BK is dispersed at minute points in the original image with a low density and a relatively large area, The reproduced color of the shaded area deteriorates. After all, in color reproduction, firstly it is preferable to minimize the color mixture of M and C, secondly it is preferable to reduce the color mixture of Y to other colors, and BK is dispersed at minute points. Is preferred. Therefore, the setting of the halftone expression pattern for each mode color (12a
In all of FIGS. To 12d), 13a to 13d, and 14a to 14d, as described above, the halftone dot center of the M recording pattern and the C recording pattern The color patterns are assigned so that the maximum distance of Y is the maximum, and the Y recording pattern is the same as the M and C recording patterns so that the Y dot becomes a long distance with respect to the dot of these patterns. Is a different pattern, and BK is also M, C and Y
And a pattern in which the dots are different and the dots are dispersed.

Thus, the preferred embodiment of the present invention is shown in FIGS.
Shown in Figure 15d. Referring to FIGS. 15a to 15d, the pattern shown in FIG. 12c and the pattern shown in FIG. 12d are set to M and C, which have the greatest influence on the color reproduction quality. That is, many pattern setting modes (FIGS. 12a to 12d)
Fig.), (Figs. 13a to 13d) and (Figs. 14a to 14d)
(Fig. 12), the pattern setting mode (Figs. 12a to 12d) in which the distance between the halftone dot centers of the two patterns is the longest is selected. Two patterns, that is, two patterns that become substantially the same pattern when many of the same patterns are spread over a large area, are set for M and C recording. In the Y recording, the halftone dots are different from the patterns in which the longest distance can be set with respect to the halftone dots of the M pattern and the C pattern, that is, the patterns for M and C are different. And further, BK
The recording pattern is set so that its halftone dot has the longest distance from the halftone dots of the M pattern, C pattern and Y pattern. That is, the patterns of M and C, which have a high degree of color reproducibility deterioration due to color mixing, have two halftone dots so that the distance between those halftone dots is maximum, and the halftone dots are shaded with respect to these halftone dots. In order to maximize the point distance, the Y pattern, for which color reproducibility is the next problem, has four halftone dots dispersed between the M and C halftone dots, and the BK pattern is It is assumed that there are eight halftone dots so as to be dispersed between the M, C and Y halftone dots.

 According to this, the color reproducibility is extremely high.

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

Referring first to Figure 1, a document 1 is placed on the platen (contact glass) 2, document illumination fluorescent lamp 3 _1, is illuminated by 3 _2, the first mirror 4 ₁ reflected light is movable thereof,
It is reflected by the second mirror 4, _second and third mirror 4 _3, through the imaging lens 5 and enters the dichroic prism 6, wherein three wavelengths of light, red (R), green (G) and blue (B) Is split into. The separated light enters CCDs 7r, 7g, and 7b, which are solid-state image pickup devices, respectively. That is, red light is incident on the CCD 7r, green light is incident on the CCD 7g, and blue light is incident on the CCD 7b.

The fluorescent lamps 3 ₁ and 3 ₂ , the first mirror 4 ₁ and the first carriage 8 are mounted, the second mirror 4 ₂ and the third mirror 4 ₃ are mounted to the second carriage 9, and the second carriage 9 is the first carriage. 8's
By moving at a speed of 1/2, the optical path length from the document 1 to the CCD is kept constant, and the first and second carriages are scanned from right to left when reading the original image. A carriage drive pulley fixed to the shaft of the carriage drive motor 10.
The first carriage 8 is coupled to the carriage driving wire 12 wound around 11, and the wire 12 is wound around a moving pulley (not shown) on the second carriage 9. This allows
By the forward and reverse rotations of the motor 10, the first carriage 8 and the second carriage move forward (original image reading scan) and return (return), and the second carriage 9 moves at half the speed of the first carriage 8. To do.

When the first carriage 8 is at the home position shown in FIG. 1, the first carriage 8 is detected by the home position sensor 39 which is a reflection type photo sensor. That is, when the first carriage 8 is driven to the right by exposure scanning and is out of 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 is detected. Reference numeral 39 indicates light reception (carriage detection), and the carriage 8 is stopped when non-light reception is changed to light reception.

Referring now to FIG. 2, the outputs of the CCDs 7r, 7g, 7b are:
After being subjected to analog / digital conversion and subjected to necessary processing in the image processing unit 100, recording color information for recording energization of each of black (BK), yellow (Y), magenta (M) and cyan (C) Is converted into a binary signal. Each of the binarized signals is supplied to the laser driver 112bk, 11
The laser beams are input to 2y, 112m, and 112c, and the respective laser drivers energize the semiconductor lasers 113bk, 113y, 113m, and 113c, thereby emitting laser light modulated with a recording color signal (binary signal).

FIG. 1 is referred to again. The emitted laser light is reflected by the rotating polygon mirrors 13bk, 13y, 13m and 13c,
After passing through the f-θ lenses 14bk, 14y, 14m and 14c, the light is reflected by the fourth mirrors 15bk, 15y, 15m and 15c and the fifth mirror 16bk, 16y, 16m and 16c, and the polygonal mirror tilt correction cylindrical lenses 17bk, 17y, 17m. And 17c, then the photosensitive drum 18b
Image-irradiates k, 18y, 18m and 18c.

The rotary polygon mirrors 13bk, 13y, 13m and 13c are fixed to the rotary shafts of the polygon mirror drive motors 41bk, 41y, 41m and 41c, and each motor rotates at a constant speed to drive the polygon mirror at a constant speed. Due to the rotation of the polygon mirror,
Scanning is performed in a direction perpendicular to the rotation direction (clockwise direction) of the photosensitive drum, that is, 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 present applicant.
The same applies to the laser scanning system shown in the figure.

The surface of the photoreceptor drum is uniformly charged by charge scorotrons 19bk, 19y, 19m and 19c connected to a negative voltage high voltage generator (not shown). When the laser light modulated by the recording signal is applied to the uniformly charged surface of the photoconductor, the charge on the surface of the photoconductor flows to the equipment ground of the drum body by photoconductive development and disappears. Here, the laser is not turned on in the portion where the original density is high, and the laser is turned on in the portion where the original density is low. As a result, the surface of the photoconductor drums 18bk, 18y, 18m, and 18c has a potential of −800V at the portion corresponding to the dark portion of the original, and −100V at the portion corresponding to the light portion of the original. An electrostatic latent image is formed corresponding to the light and shade. This electrostatic latent image is developed by a black developing unit 20bk, a yellow developing unit 20y, a magenta developing unit 20m and an undeveloping unit 20c, respectively, and black, yellow and magenta are respectively formed on the surfaces of the photoconductor drums 18bk, 18y, 18m and 18c. And forming a cyan toner image. The toner in the developing unit is positively charged by agitation, and the developing unit is biased to about -200 V by a developing bias generator (not shown). A corresponding toner image is formed.

On the other hand, the recording paper 267 stored in the transfer paper cassette 22 is fed out by the feeding operation of the feed roller 259, and sent to the transfer belt 25 at a predetermined timing by the registration roller 24. The recording paper placed on the transfer belt 25 is the transfer belt.
By moving 25, photoconductor drums 18bk, 18y, 18m and 18c
Of the black, yellow, magenta and cyan toners on the recording paper by the action of the transfer corotron at the lower part of the transfer belt while passing through the lower part of the transfer belt sequentially and passing through the photosensitive drums 18bk, 18y, 18m and 18c. Are sequentially transferred.
The transferred recording paper is then sent to the thermal fixing unit 36, where the toner is fixed to the recording paper, and the recording paper is discharged to the tray 37.

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

The cleaner unit 21bk for collecting the black toner and the black developing unit 20bk are connected by the toner collecting pipe 42, and the black toner collected by the cleaner unit 21bk is collected in the developing unit 20bk. The black toner is reversely transferred from the recording paper to the photoconductor drum 18y at the time of transfer, and the yellow, magenta, and cyan toners collected by the cleaner units 21y, 21m, and 21c are different from the different color developing device in the preceding stage of those units. Since the toner is mixed, it will not be collected for reuse.

The transfer belt 25 that feeds the recording paper in the direction of the photosensitive drum 18bk to 18c is stretched around the idle roller 26, the drive roller 27, the idle roller 28, and the idle roller 30, and is driven to rotate counterclockwise by the drive roller 27. To be done. Drive roller 27
Is pivotally attached to the left end of a lever 31 pivotally attached to a shaft 32. At the right end of the lever 31, a black mode setting solenoid plunger 35 (not shown) is pivotally mounted. A compression coil spring 34 is arranged between the plunger 35 and the shaft 32,
This spring 34 gives the lever 31 a rotational force in the clockwise direction.

When the black mode setting solenoid is not energized (color mode), as shown in FIG. 1, the transfer belt 25 on which the recording paper is placed is in contact with the photosensitive drums 44bk, 44y, 44m and 44c. In this state, when the recording paper is placed on the transfer belt 25 and toner images are formed on all the drums, the toner image of each image is transferred onto the recording paper as the recording paper moves (color mode). When the black mode setting solenoid is energized (black mode), the lever 31 rotates counterclockwise against the repulsive force of the compression coil spring 34, the drive roller moves down 5 mm, and the transfer belt 25
Is separated from the photosensitive drums 44y, 44m and 44c and remains in contact with the photosensitive drum 44bk. In this state, the recording paper on the transfer belt 25 is only in contact with the photoconductor drum 44bk, so only the black toner image is transferred to the recording paper (black mode). Since the recording paper does not contact the photosensitive drums 44y, 44m and 44c,
No attached toner (residual toner) of 4m and 44c is attached, and no stain such as yellow, magenta, and cyan appears.
That is, in copying in the black mode, a copy similar to that of a normal monochrome black copying machine can be obtained.

The console board 300 has a copy start switch, a color mode / black mode designation switch 302 (the switch key is turned off immediately after the power is turned on, 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 twice, the switch key is turned off and the color mode is set and the black mode setting solenoid is de-energized.) In addition, it is equipped with other input key switches, charactor displays and indicators.

Next, the operation timing of the main part of the copying mechanism will be described. The modulation energization of the laser 43bk based on the recording signal is started at substantially the same timing as the start of the exposure scanning of the first carriage 8, and the lasers 43y, 43m and 43c are respectively the photosensitive drums.
The modulation bias is started with a delay of the movement time Ty, Tm, and Tc of the transfer belt 25 by a distance of 44y, 44m, and 44c from 44bk. The transfer corotrons 29bk, 29y, 29m, and 29c respectively take a predetermined time (the time required for the laser irradiation position on the photosensitive drum to reach the transfer corotron) from the start of the modulation bias of the lasers 43bk, 43y, 43m, and 43c. Fired after a delay.

Please refer to FIG. The image processing unit 100 includes CCDs 7r and 7
The three color image signals read by g and 7b are converted into black (BK), yellow (Y), magenta (M) and cyan (C) recording signals required for recording. The BK recording signal is given to the laser driver 112bk as it is, but the Y, M and C recording signals are stored in the buffer memories 108y, 108m and 108c, respectively, which are the original recording color gradation data, and then the delay time Ty, After a time delay of reading after Tm and Tc and converting into a recording signal, the laser driver 11
Feed 2y, 112m and 112c. The image processing unit 1
00 is supplied with the three-color signals from the CCDs 7r, 7g and 7b in the copying machine mode as described above. In the graphics mode, the three-color signals are supplied from the outside of the copying machine to the external interface 11.
Given through 7.

Shading correction circuit 101 of image processing unit 100
Is the color gradation data obtained by A / D converting the output signals of the CCD7r, 7g and 7b into 8 bits, and correcting the uneven light intensity and the sensitivity variation of the internal unit elements of the CCD7r, 7g and 7b. Create read color gradation data.

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

The γ-correction circuit 103 that receives the output (color gradation data) of the multiplexer 102 changes the gradation (input gradation data) according to the characteristics of the photoconductor, and also the gradation by the operation buttons of the console 300. And the input 8-bit data is changed to output 6-bit data. Since the output is 6 bits, data indicating one of 64 gradations will be output. The 6-bit three-color gradation data indicating the gradations of red (R), green (G), and blue (B) output from the γ correction circuit 103 are supplied to a complementary color generation / black separation circuit 104.

Complementary color generation and complementary color generation in the black separation circuit 104 is to read the names of the respective color read signals to the recording color signals, and the red (R) gradation data is cyan (C) gradation data and the green (G) floor. The tone data is converted (read) into magenta (M) tone data, and the blue tone data (B) is converted into yellow tone data (Y). C, M and Y
The gradation data is given to the averaged data compression circuit 105 as it is. If all of these gradation data indicate high density, black recording may be performed. Therefore, the digital comparator in the circuit 104 converts the C, M, and Y gradation data to respective threshold setting switches. Compare with the set reference value data. Each of the digital comparators compares 8-bit data with each other.
Data with the upper 2 bits of the level added (input data)
Is set to L level with the least significant digit 1 bit and the uppermost digit 3 bits, and is compared with 8-bit data (reference value data) in which the second to fourth bits from the lowermost are reference value data set by the switch for threshold setting. , L is given to the NAND gate if the input data is less than or equal to the reference value data, and H is given if it is over the reference value data.
The NAND gate is L (black) when all the comparators are giving an L signal, and is H when one of them is giving an H signal.
(White) is output and given to the data selector 110. To explain this in more detail, the gradation data input of the comparator is in the range of 0 to 3FH in hexadecimal 6-bit data. When the value is 0, black is output, as the value increases, white is output, and the output black At the time of insertion, L is black and H is white. Therefore 8
The MSB side 2 bits (Q6, 7) of the bit input data are input to L, and the lower 6 bits (Q0 to 5) are input C, M, and Y gradation data, respectively. The comparison data side uses a rotary type dip switch so that the comparison level can be set to 7 steps.
Furthermore, since the black level is set, if black is included including too much white color, halftone (gray) can be recorded as black with high resolution, but black is often generated in terms of color balance, which is not preferable. So for the time being 7 to intermediate level
Since the 5th and 6th bits are also set to L so that it can be set in stages, and there is no need to set it very finely, 1 bit on the LSB side is set to L and the set value from the dip switch is input to the middle 3 bits (P1 to 3). There is. The dip switch setting is now 010
, The reference value is 0000010, and when the data of each of C, M, and Y are all less than this value, that is, the decimal number 0 to 3
During this period, the output of the comparator is L and the black (BK) output is L
(Black) Here, the DIP switch for setting, C, M
It is also used for comparison judgment of Y and Y, but by using three sets, it is possible to set each color, and by setting the setting range width of each color using the minimum and maximum setting switches, the specific color is set. It is also possible to output a black pattern with good resolution.

The averaged data compression circuit 105 of the image processing unit 100
4 × 4 with 6-bit gradation data for one image
The image data is averaged and output as 6-bit gradation data. In the case of this embodiment, the processing mode in which the sizes of the input image and the output image are the same is standard, and the input data (read value from CCD) is A / D converted into 8-bit data and converted into 6-bit data by γ correction. However, the output data to the laser driver is laser on / off (1
Bit) data. It is possible to separate 64 levels of density by inputting 6-bit data. Therefore, the input data 8 ×
The density of 8 pixels is averaged to obtain density data. Further, the data amount and the processing speed are compressed to 1/64 by this averaging, and the data capacity when storing and the cost of the hardware part are reduced.

Next, the masking processing circuit 106 and the UCR processing circuit 107 will be described. The formula for the masking process is generally Yi, Mi, Ci: unmasked _{data, Y 0, M 0, C} 0: the masking after data.

In addition, UCR processing as a general formula, Can be represented by

Therefore, in this example, using these equations and using the product of both coefficients, Is calculated to find a new coefficient. Masking process and
Coefficient (a ₁₁ ″) in the above equation that performs both UCR processing simultaneously
Etc.) is calculated in advance and substituted into the above arithmetic expression, and the calculated values (Y ₀ ′ etc .: UCR processing circuit 107) associated with the planned inputs Yi, Mi and Ci (6 bits each) of the masking processing circuit 106. Output) is stored in ROM in advance. Therefore, in this embodiment, the masking processing circuit 106 and the UCR processing circuit 107 are composed of a set of ROMs, and the data of the addresses specified by the inputs Y, M and C to the masking processing circuit 106 are the UCR processing circuit. Buffer memory 108 as output of 107
y, 108m, 108c and the gradation processing circuit 109. Generally speaking, the masking processing circuit 106 corrects the Y, M, and C signals in accordance with the characteristics of the spectral reflection wavelength of the recording image forming toner, and the UCR processing circuit 107 superimposes the toners of the respective colors. The correction for color balance in matching is performed.

Next, the buffer memories 108y and 108m of the image processing unit 100
And 108c. These simply generate a time delay corresponding to the distance between the photosensitive drums.
The write timing of each memory is the same, but the read timing is as follows: the memory 108y matches the modulation activation timing of the laser 43y, the memory 108m matches the modulation activation timing of the laser 43m, and the memory 108c reads the laser 43c. It is performed according to the timing of modulation activation, and is different for each. The capacity of each memory is when the maximum size is A3, and the memory 108y has a minimum of 24% of the maximum required size of A3 documents, and the memory 10
It may be 48% at 8 m and 72% at the memory 108c. For example, if the CCD reading pixel density is 400 dpi (dots per inch: 15.75 dots / mm), the memory 108y is approximately 87K.
Byte, memory 108m is about 174K bytes, also memory
The capacity of 108c is about 261 bytes. In this embodiment, since 64-gradation, 6-bit data is handled, the capacities of the memories 108y, 108m and 108c are 87K, 174K and 261K bytes, respectively. When the memory address is calculated in 6-bit units from the byte unit (8 bits), the memory becomes 108y: 116K × 6 bits, memory 108m: 232K × 6 bits, and memory 108c: 348K × 6 bits.

Next, the density pattern processing circuit 109 of the image processing unit 100
Will be explained. This circuit 109 is a circuit for generating a pattern corresponding to the density from the recording density data of each of Y, M, C and BK. The BK gradation processing circuit 109bk, Y gradation processing circuit 109y, M gradation It is composed of a processing circuit 109m and a C gradation processing circuit 109c.

The 6-bit grayscale data can represent density information of 64 grayscales (65 grayscales including 0 to which no pattern is assigned). Ideally, if the dot diameter of one dot can be varied to 64 steps, the resolution will not be reduced, but dot diameter modulation is only stable at most about 4 steps in the laser beam electrophotographic method. There are many combinations of density patterning and beam modulation. Here, a processing method of 64 gradation expression using an 8 × 8 matrix is used.

 FIG. 3 shows the configuration of the Y gradation processing circuit 109y.

The pattern memory 1012 is a ROM, and as shown in FIG. 15a, a recording information bit is provided only at the position 1 of the threshold value from a halftone expression pattern (threshold distribution pattern) in which threshold data is distributed in an 8 × 8 matrix. Density 1 specified by density 1 in which non-recording information bits are written at other threshold positions.
Pattern: a density i pattern in which recording information bits are written at positions of i or less of the threshold value and non-recording information bits are written at positions of other threshold values, and the density i pattern is specified by the density i ... 64, which is a total of 64 halftone expression patterns of the recording information bit expression, are written with the recording information bits at the positions of 64 or less (that is, the whole) and the density 64 pattern specified by the density 64. The X allocation pattern has a halftone dot center in the hatched area shown in FIG. 15a. The shaded cells in FIG. 15a indicate the positions to which the recording information bits are assigned when the density data indicates 16.

The other gradation processing circuits 109m, 109c and 109bk have the same hardware configuration as the circuit 109y. However, the halftone pattern data stored in the pattern memory is different, and 64 patterns created based on the original pattern shown in FIG. 15c are stored in the pattern memory (not shown) of the circuit 109m. In the pattern memory (not shown), 64 patterns created based on the original pattern shown in FIG.
The k pattern memory (not shown) stores 64 patterns created based on the original pattern shown in FIG. 15b.

Next, halftone processing for one color Y will be described by taking the gradation distance circuit 109y as an example. The processing operations of the other gradation processing circuits are the same.

As described above, one halftone expression pattern (mother matrix pattern) in one group is specified by the recording density data, and information of a child matrix pattern forming a part of the mother matrix pattern is extracted. Image information is obtained in a form assigned to gradation data. According to this, since the gradation pattern is updated in the unit of the child matrix pattern, the resolution is increased, and thereby, the reproducibility of the edge portion of the face outline, line drawing, etc. of the photographic image is improved. For example, in the outline of the image, the corresponding child matrix pattern becomes a part of the high-density mother matrix pattern, so that the outline clearly appears, and in the low-density portion outside the outline, the corresponding child matrix pattern. Since the pattern becomes part of the low-density mother matrix pattern, a low-density image appears and the outline becomes clear. Further, since the large (mother) matrix pattern is specified by the recording density data, the smoothness is improved in the portion where the poorly changing gradation gradually changes. In other words, the number of child matrix patterns, each of which constitutes a mother matrix pattern corresponding to the recording density data, is arranged in an area corresponding to one mother matrix pattern of the reproduced image.

However, since the mother matrix pattern has similar patterns when the expression density is close, the number of child matrix patterns constituting one mother matrix pattern is small in the image portion where the density is gradually changing. Is similar to one specific mother matrix pattern, and the number of expressed gradations is about the same as the number of expressed gradations represented by the mother matrix pattern. Moreover, Figures 15a to 15d
As shown in the figure, a unique arbitrary halftone dot center can be set for each color. As described later, the mother matrix pattern MMP
With m in the main scanning direction and n in the sub scanning direction, m ×
It is divided into n child matrix patterns CMP _{11 to} CMP _mn , and the head of the letter indicates the position of the child matrix pattern in the main scanning direction in the mother matrix pattern, and the latter half of the letter indicates the position in the sub scanning direction. And this And m × n pieces of grayscale data, which are also ICD ₁₁ to ICD _mn If the image information for one mother matrix pattern is to be obtained, the information of the child matrix pattern CMPij of the mother matrix pattern specified by the gradation data ICDij is obtained as the image information of the bit distribution for the gradation data ICDij. That is, the position of the child matrix pattern for obtaining the image information corresponding to each of the arrangement of one mother matrix pattern and the number m × n of gradation data corresponds to the position of the gradation data in the mother matrix pattern. Position. According to this, in the area corresponding to one mother matrix pattern of the reproduced image, the information is that of each mother matrix pattern corresponding to each gradation data, but the position is a predetermined number that constitutes one mother matrix pattern as a whole. It has a shape in which m × n child matrix patterns at positions are arranged. According to this, since the mother matrix pattern is similar when the expression density is close, in the image portion where the density is slowly changing, the reproduced image by the m × n child matrix patterns is specified. The similarity with one mother matrix pattern is further increased, the number of expressed gradations becomes equal to the number of expressed gradations represented by the mother matrix pattern, and the density is expressed by the conventional fixed density pattern method using the mother matrix pattern. Be equivalent. Further, for example, in the contour line of the image, the corresponding child matrix pattern becomes a part of the high-density mother matrix pattern, so that the contour line clearly appears, and in the low-density portion outside the contour line, it corresponds thereto. Since the child matrix pattern becomes a part of the low-density mother matrix pattern, a low-density image appears, and the outline becomes clearer.

The mother matrix pattern of one group has density No. 1 to 64
Each of the mother matrix patterns has a structure of 8 × 8 bits (pixels) that expresses 64 gradations (65 gradations with a density of 0, though it does not have a pattern of density 0) As described above, is created based on the original mother pattern (FIG. 15a) having 64 pieces of threshold data.

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. 5a, the odd-numbered one of the recording density data for one row is
Mother matrix pattern for density (1 out of 64 types)
Is specified and the left half A is extracted as recording data, the mother matrix pattern corresponding to the density of the even number is specified, and the right half B thereof is extracted as recording data. In the child matrix pattern division shown in FIG. 5b, the mother matrix pattern (one of 64 types) corresponding to the density is specified in each of the recording density data of the odd numbered rows, and the upper half A is extracted as the recording data. Then, the mother matrix pattern corresponding to the density is specified in each of the recording density data of the odd-numbered rows, and the lower half B thereof is extracted as the recording data.

FIG. 5c shows an example in which the mother matrix pattern is divided into four child matrices A to D. In this example, the mother matrix pattern (one of 64 types) is specified by the odd-numbered recording density data of the odd-numbered row, and the data of the upper left 1/4 minute (corresponding to part A in FIG. 5c) is extracted. , The mother matrix pattern (one of 64 types) is specified by the even numbered recording density data of the odd numbered row, and the data of the upper right 1/4 minute (corresponding part B in FIG. 5c) is extracted and The mother matrix pattern (one of 64 types) is specified by the odd-numbered recording density data of the row, and the data of the lower left 1/4 minute (corresponding part C in FIG. 5c) is extracted and the even-numbered row is even. The mother matrix pattern (one of 64 types) is specified by the recording density data, and the data in the lower right quarter (D corresponding portion in FIG. 5c) is extracted.

When the mother matrix pattern is divided into 16 child matrix patterns A to P as shown in FIG. 5d, and when the mother matrix pattern is divided into 64 child matrix patterns A, B, C, as shown in FIG. 5e. Similarly, when dividing into ..., similarly, the mother matrix pattern is first specified by the recording density data, and then the image information of the child matrix pattern at the position corresponding to the allocation position of the density data for the mother matrix pattern is extracted. .

Now, the recording density data shown in FIG. 7a has arrived, and the mother matrix pattern (recording information bit distribution) is
Assuming that there are 64 kinds of those corresponding to the concentrations 1 to 64 shown in the figure,
And when 4 divisions are specified, the gradation data is The reproduced image data is the analysis shown in Fig. 8a (the values in Fig. 8a correspond to the density values in Fig. 10, and the alphabet is
5c shows the divided part). That is, the child matrix patterns are arranged as follows in accordance with the distribution of the incoming recording density data (FIG. 7a).

The number at the beginning refers to the mother matrix pattern of the mother matrix pattern 1 assigned to the density indicated by the number.

In the above, the rectangular area surrounded by the line is the size of one mother matrix pattern. In FIG. 8a, a rectangular area surrounded by a bold line is the size of one mother matrix pattern. The reproduced image has the form shown in FIG. 9a.

When the gradation data is arranged as shown in FIG. 7b,
When the image information is reproduced in 16 divisions (as shown in FIG. 5d),
The arrangement of the child matrix pattern shown in FIG.

In FIG. 8b, the rectangular area surrounded by the thick line is the size of one mother matrix pattern. In FIG. 8a, the numbers are
It refers to the mother matrix pattern of the mother matrix pattern 4 assigned to the density indicated by the numeral.
The reproduced image has the form shown in FIG. 9b.

The child matrix pattern A shown in FIG.
The extraction of the child matrix patterns A and C shown in FIG.
This is performed by taking the logical product of the 1-byte mask pattern F0H shown in FIG. 4a and the 1-line data of the mother matrix pattern to be extracted in the main scanning direction. When the logical product is obtained, the logical product is stored in a page memory or a buffer memory. This is performed for eight lines.

In the mask pattern shown in FIG. 4a, "1" (shown by oblique lines) is stored in a portion to be extracted, and "0" is stored in a portion not to be extracted. That is, the mask pattern F0H shown in FIG. 4a is data indicating F0H.

The child matrix pattern B shown in FIG.
The extraction of the child matrix patterns B and D shown in FIG.
This is performed by taking the logical product of the one-byte mask pattern 0FH shown in FIG. 4a and the data of one line in the main scanning direction of the mother matrix pattern to be extracted. When the logical product is taken, the page memory or the buffer memory stores "0" of the non-extracted part of the previous logical product memory. Therefore, the data in the memory target area of the page memory or the buffer memory is read and The logical sum of the obtained logical product data is calculated, and this logical sum is updated and stored in the page memory or the buffer memory. This is performed for eight lines. Also in the mask pattern OFH shown in FIG. 4a, "1" (indicated by hatching in the figure) is stored in the portion to be extracted, and "0" is stored in the portion not to be extracted. The mask pattern 0FH shown in FIG. 4a is data indicating 0FH.

Similarly, in the extraction of the pattern information in the child matrix pattern division shown in FIG. 5d, the extraction of the child matrix patterns A, E, I and M uses the mask pattern COH shown in FIG. A mask pattern of 30H is used for the removal of F, J and N, a mask pattern of 0CH is used for the removal of C, G, K and O, and a 03H is used for the removal of D, H, L and P. Use a mask pattern.

Then, the data (logical product) obtained by extracting A, E, I and M is written as it is to the page memory or the buffer memory, but A, E, I and M, C, G, K and O, and D, H The data (logical product) from which L, P and L are extracted is logically ORed with the data already written in the page memory or buffer memory, and then updated in the page memory or buffer memory.

In the child pattern division shown in FIG. 5e, information extraction of the child matrix pattern is similarly performed.

In the above description, the mother matrix pattern is 1 byte in the main scanning direction and is in byte units, and the child matrix patterns are all 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 because it does not matter whether it is a byte unit in terms of information processing.

However, in the main scanning direction, it is preferable to set both the mother matrix pattern and the child matrix pattern in byte units first, because information can be processed in byte units at high speed. Therefore, in the above-described embodiment, the child matrix pattern is processed in byte units by the logical processing using the mask pattern. Therefore, according to this logical processing, all the child matrix patterns constituting one mother matrix pattern do not have to be the same size. When the mother matrix pattern is in units of bytes, the child matrix pattern can be easily processed in units of bytes as described above.

However, when both the number of bits in the main scanning direction of the mother matrix pattern and the number of bits in the main scanning direction are fractions of bytes, the processing becomes complicated.

Therefore, in such a case, focusing on the number of bits c in the main scanning direction of the child matrix pattern, c × d = e bytes,
If d and e are the minimum integers, the data in the main scanning direction of the child matrix pattern and one column of data are continuously written in e bytes c times, and then in the e byte, a mask pattern that leaves only one column of required data. The logical product is taken and the logical product data is written in the page memory or the buffer memory. When the child matrix pattern is the leftmost one, the logical product data is written as it is to the page memory or the buffer memory, but in the case of the child matrix pattern at other positions, the data of the page memory or the buffer memory is further written. The logical sum is obtained and then written to the page memory or the buffer memory.

As described above, since a large mother matrix pattern is used, the number of gradations can be increased, and since the mother matrix pattern can be easily configured in bytes, information processing can be easily performed in bytes. Since the child matrix pattern is assigned to the gradation data, there is an advantage that the resolution is increased.

Further, there is an advantage that the magnification of the reproduced image can be changed. For example, one child matrix pattern is assigned to one gradation data, but in the child matrix pattern division shown in FIGS. 5a to 5e, the size (number of bits, that is, the number of dots) of each child matrix pattern is different. Therefore, the magnification of the reproduced image differs between the child matrix pattern divisions shown in FIGS. 5a to 5e.

That is, assuming that one piece of gradation data now indicates the density of the entire area of 4 dots (corresponding to the child matrix shown in FIG. 5d) of the original image, the child matrix pattern division shown in FIG. 5d. , The reproduced image has a 1: 1 magnification with respect to the original image, but in the child matrix pattern division of FIG. 5a, the reproduced image is enlarged 2 times in the main scanning direction and 4 times in the sub scanning direction. In the sub-matrix pattern division shown in FIG. 5b, a reproduced image is enlarged four times in the main scanning direction and twice in the sub-scanning direction, and in the sub-matrix pattern division shown in FIG. The resulting reproduced image is twice as large in both directions, and in the sub-matrix pattern division shown in Fig. 5e, it is 1/2 in both the main scanning direction and the sub-scanning direction.
The reproduced image is slightly reduced.

Therefore, for example, as shown in FIGS. 5c to 5e, a plurality of child matrix pattern divisions are set, and one division mode is specified in accordance with magnification instruction data M (M indicates the number of divisions). Then, the magnification of the reproduced image can be selected. In order to increase the selectable magnification, it is preferable to increase the size of the mother matrix pattern.

The configuration and operation of the Y gradation processing circuit 109y shown in FIG. 3 will be described here. The pattern memory 1012 is a ROM storing 64 mother matrix patterns created based on the original pattern shown in FIG. 15a. , One of the patterns is specified by the recording density data output from the memory 108y. Data of a specific part (all rows: 8 bits) of the specified pattern is specified by the microprocessor 1010,
Read from the memory 1012 is supplied to the AND gate LG ₁ in. Andgate LG ₁ , microprocessor 1010
Gives the aforementioned mask pattern (1 byte). In logical processing by the AND gate LG _1, so that the data in the child matrix pattern is removed. The extracted data is given to the data selector G ₃ . The selector G ₃ and the OR gate LG ₂ are for processing the extracted data into a bit distribution corresponding to the recording surface, and by the read / write control of these and the microprocessor, a memory capacity of at least one row (8 dot width) or more is provided. The extracted data is surface-expanded in the buffer memory included therein. The data expanded in the buffer memory is transferred to the laser driver 112y on a row-by-row basis.

6a and 6b show the data processing operation of the microprocessor 1010. To explain this, the computer
In 1010, when proceeding to gradation data processing for converting the recording density data received from the memory 108y into recording data (data indicating the recording dot distribution), first, magnification instruction data M (M is the number of divisions of the mother matrix pattern = child matrix pattern) Read the number), the number of divisions in the main scanning direction and the sub scanning direction,
That is, $ M is set in the register L (step 1:
The word step is omitted in parentheses below). In this example, M is 4 (Fig. 5c), 16 (Fig. 5d) and 64.
(Fig. 5e). Note that M = 16
(Extraction of the child matrix in Fig. 5d) is the standard, and the reproduction image is the same size as the original image.

Next, the microprocessor 1010 sets 1 (j = 1) to a counter V for grasping the position (j) of the sub matrix pattern to be processed in the sub-scanning direction (step 2),
The counter H for grasping the position (i) in the main scanning direction is set to 1 (i = 1) (step 3), and data from the memory 108y is read (step 4). When the input data is the recording density data, the content of the line counter LC is set to a value obtained by multiplying the content of the register L by the value obtained by subtracting 1 from the content of the counter V (8).

Next, the microprocessor 1010 specifies a mask pattern based on the magnification instruction data M and the contents of the counters V and H (9). That is, a child matrix pattern CMPij from which image data is to be extracted is specified based on the number of divisions M and the contents of the counters V and H (i is the contents of the counter H, j is the contents of the counter V, and M is FIG. The number of divisions that indicates which division mode in FIG. 5e), the matrix pattern to be assigned to this child matrix pattern (for example, FIGS. 4a and 4b
Figure) is specified.

Next, the microprocessor 1010 uses the pattern memory 1012.
1 byte data of the line (aligned in the main scanning direction) indicated by the content of the line counter LC is stored in a buffer memory BUF (internal register) (10), and the data of the buffer memory BUF and the data of the mask pattern are ANDed. ANDs given to the gate LG _1, to update the memory of the logical data in the buffer memory BUF (11), the counter H
(12).

When the content of the counter H is 1, this indicates that the child matrix pattern for extracting information is the leftmost one in the mother matrix pattern.
Write the BUF data as is to the buffer memory 1020 (1
Five).

If the content of the counter H is not 1, the data of the leftmost child matrix pattern has already been written in the memory 1020, and by this writing, the mask pattern data “0” is written in the other child matrix pattern writing section. Since it is stored in memory, the LC line (LC is the content of the counter LC) (1 byte) of the previously written pattern data is read from the memory 1020 and stored in the buffer memory MBUF (internal register). The data in the buffer memory MBUF and the data in the buffer memory BUF are given to the OR gate LG ₂ to perform logical allocation, the logical sum data is updated and stored in the buffer memory BUF (14), and the data in the buffer memory BUF is updated to the page memory 1020 (15).

Next, the microprocessor 1010 increments the line counter LC by one (16), and the contents of the line counter LC and the number of lines of the child matrix pattern Compared with (17), the content of Cain counter LC is the number of lines If not, the process proceeds to the next line of image extraction, but if it does, the counter H is incremented by one (18), and the contents of the counter H are compared with the contents of the register L (19). If the former is greater than the latter, image extraction has been completed for the child matrix pattern located at the leftmost position in the main scanning direction in the mother matrix pattern,
To advance the next process to the leftmost child matrix pattern, the content of the counter H is set to 1 (20), and the process proceeds to the next data reading (4).

When the data read in the data read (4) indicates the end of halftone processing, the microprocessor
1010 returns to the main routine. When the data is line feed "LF", the counter V is incremented by one (21), and the contents of the counter V are compared with the contents of the register L (22). If the former is larger than the latter, it means that the image processing for one mother matrix pattern has been completed, so the counter V is set to 1 (23) and the process returns to the data reading (4). When the data is the carriage return “CR”, it means that the image processing for the width of one mother matrix pattern in the main scanning direction has been completed.
Is set (3), and the process proceeds to data reading (4).

In the above description, a mother matrix pattern (halftone expression pattern) of 64 types as one group is formed using the original pattern (FIG. 15a) having threshold data, and this is stored in the memory 1012 in advance. With reference to the mode, the memory 1012 stores the original pattern as a halftone expression pattern, compares the recording density data given from the memory 108y with each threshold of the original pattern, and A mother matrix pattern may be created, or recording density data may be compared with a partial threshold value of the original pattern to obtain recording / non-recording bit information, and recording may be performed based on this. Alternatively, prior to gradation processing, the original pattern and each of the recording density gradation data (representing 1 to 64) are compared to create one group (64) of mother matrix patterns, which is stored in the RAM. It may be stored in a memory such as. In this way, the data in the memory 1012 can be reduced.

With the same hardware configuration and control operation as the gradation processing circuit 109y described above, the gradation processing circuits 109m, 109c and 109bk
Generates recording image data of magenta M, cyan C and black BK, respectively. These differ in that the halftone dot centers of the mother matrix (halftone expression pattern) stored in the pattern memory are at different positions based on the original patterns shown in FIGS. 15a to 15d, respectively. .

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a mechanical structure according to an embodiment of the present invention. FIG. 2 is a block diagram showing the configuration of the electric system of the embodiment. FIG. 3 is a block diagram showing a configuration of the gradation processing circuit 109y shown in FIG. FIGS. 4a and 4b are plan views showing mask patterns used for extracting a child matrix pattern. 5a, 5b, 5c, 5d and 5e show the number of modes in which the halftone expression pattern is divided into child patterns (partial patterns) A, B, C,. It is a top view which shows a seed. 6a and 6b are flow charts showing the recorded image data processing operation of the microprocessor 1010 shown in FIG. 7a and 7b are plan views showing the distribution of the recording density data corresponding to the recording surface, and the numbers in the figures indicate the densities (decimal numbers) indicated by the recording density data. 8a and 8b respectively correspond to the recording density data distributions shown in FIGS. 7a and 7b, respectively, and extract the recording data from the halftone expression pattern by dividing FIGS. 5c and 5d, respectively. FIG. 4 is a plan view showing a print data distribution when assigned to a print surface. 9a and 9b are plan views showing recording information distributions (shaded areas) when recording data is extracted from the halftone expression pattern shown in FIG. 10 in the mode shown in FIGS. 8a and 8b, respectively. It is. FIG. 10 is a plan view showing a group of halftone expression patterns created based on original data different from the original data shown in FIGS. 15a to 15d. FIGS. 11a, 11b and 11c are plan views showing basic pattern examples of halftone expression patterns used in the present invention, and the hatched lines in the figure indicate when the recording density data indicates 16. The position to which the recording information bit is assigned is shown. FIGS. 12a, 12b, 12c and 12d are plan views showing halftone expression patterns assigned to respective recording colors based on the basic pattern shown in FIG. 11a, and FIG. FIG. 3 is a plan view showing a color distribution of a surface recorded based on these patterns when each color recording density data is shown by 16, where 0 is a Y recording portion, 1 is a BK recording portion,
2 shows the M recording portion, and 3 shows the C recording portion. FIGS. 13a, 13b, 13c and 13d are plan views showing halftone expression patterns assigned to each recording color based on the basic pattern shown in FIG. 11b, and FIG. 13e shows FIG. 3 is a plan view showing a color distribution of a surface recorded based on these patterns when each color recording density data is shown by 16, where 0 is a Y recording portion, 1 is a BK recording portion,
2 shows the M recording portion, and 3 shows the C recording portion. FIGS. 14a, 14b, 14c and 14d are plan views showing halftone expression patterns assigned to each recording color based on the basic pattern shown in FIG. 11c, and FIG. FIG. 3 is a plan view showing a color distribution of a surface recorded based on these patterns when each color recording density data is shown by 16, where 0 is a Y recording portion, 1 is a BK recording portion,
2 shows the M recording portion, and 3 shows the C recording portion. Figure 15a is based on the basic pattern shown in Figure 11b.
FIG. b shows a slight modification of the basic pattern shown in FIG. 11c, and FIGS. 15c and 15d show halftone expression patterns assigned to each recording color based on the basic pattern shown in FIG. 11a. FIG. 15e is a plan view showing a color distribution of a surface recorded based on these patterns when each color recording density data is shown by 16, and FIG.
Indicates a Y recording portion, 1 indicates a BK recording portion, 2 indicates an M recording portion, and 3 indicates a C recording portion. 1: Original, 2: Platen 3 ₁ , 3 ₂ : Fluorescent lamp, 4 ₁ to 4 ₃ : Mirror 5: Variable magnification lens unit 6: Dichroic prism 7r, 7g, 7b: CCD, 8: 1st carriage 9: 2nd Carriage 10: Carriage drive motor 11: Pulley, 12: Wire (1 to 12: Color image reading means) 13bk, 13y, 13m, 13c: Polyhedral mirror 14bk, 14y, 14m, 14c: f-θ lens 15bk, 15y, 15m , 15c, 16bk, 16y, 16m, 16c: Mirror 17bk, 17y, 17m, 17c: Cylindrical lens 18bk, 18y, 18m, 18c: Photosensitive drum 19bk, 19y, 19m, 19c: Charge scorotron 20bk, 20y, 20m, 20c: Developing device 21bk, 21y, 21m, 21c: Cleaner 22: Paper feed cut, 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: Lever, 32: Axis 33: Pin, 34: Compression coil spring 35: Black copy mode setting solenoid plunger 36: Fixer, 37: Tray (13 to 37, 41 to 46, 112: Recording means ) 39: Home Position 40: Carriage guide bar 41bk, 41y, 41m, 41c: Polyhedral drive motor 42: Toner recovery pipe 43bk, 43y, 43m, 43c: Laser 44bk, 44y, 44m, 44c: Beam sensor 45: Photoconductor drum drive motor 46: Motor driver 100: Image processing unit 104y, 104m, 104c: Digital comparator 104sh: Rotary dip switch (101 to 107: Color component data processing means) 109: Gradation processing circuit, 109y: Y gradation processing circuit 109m: M gradation processing circuit, 109c: C gradation processing circuit 109bk: BK gradation processing circuit 1012: Pattern memory 1010: Microprocessor (pattern information reading means) 200: Microprocessor system 300: Console 301: Copy start key switch 302: Full color / single color black mode selection key switch

Claims (5)

(57) [Claims] 1. A color image is color-separated into a plurality of colors, image density is converted into digital data for each color component, and the digital data is processed into color component recording density data; Halftone expression pattern having a plurality of threshold data corresponding to one of the threshold data of a predetermined number of dots, or all of the threshold data is compared with each value of the recording density data in the planned range, and the predetermined number of dots is supported. The color component recording density data is converted into recording and non-recording bit information using a halftone expression pattern consisting of a number of bit distribution patterns corresponding to the range of recording density data, which is the recording and non-recording bit distribution. Recording / non-recording bit information is associated with one dot of the recording medium for each color component, and a predetermined color is recorded in the dot with which the recording information bit is associated; in digital color image reproduction processing: little In the halftone expression pattern used for the first color recording and the second color recording, when a predetermined area is recorded by using it, the recording information bit corresponds to the recording density and the recording information bit becomes a predetermined point of the X and Y coordinates. Recording information bit distribution, and the predetermined points are different positions for each color and are a plurality of points dispersed for each color. One set is associated with each color component, and one set is associated with each color component. When the halftone expression pattern is used and when the color component recording density data is converted into recording and non-recording bit information, the color component recording density data is obtained from the halftone expression pattern specified by the color component recording density data. Based on the coordinates of the pixels of the original image, a region for a plurality of dots of a part of the halftone expression pattern is regularly cut out as a child matrix pattern corresponding to the pixels of the original image, and the child matrix is extracted. Recording obtained from the scan pattern, and outputs the non-recording bit information as image information corresponding to the color component recording density data, wherein the digital color image reproduction processing method. 2. The halftone expression pattern has a size M.N.
2. The digital color image reproduction processing method according to claim 1, wherein the gradation of the maximum number of dots M · N is determined by the following equation. 3. The halftone expression pattern used for the first color recording and the halftone expression pattern used for the second color recording are substantially the same pattern when many of them are surface-developed. Claim 1 (1), wherein the predetermined point of the second color record and the predetermined point of the second color record are those in which threshold data or recording or non-recording data is distributed so as to be distributed at positions separated by a maximum distance. ) The method of digital color image reproduction processing according to the item. 4. A halftone expression pattern MMP is divided into m × n child matrix patterns CMP _{11 to} CMP _mn with m in the main scanning direction and n in the sub-scanning direction, and the beginning of the letter is MMP
, The position of the child matrix pattern in the main scanning direction, and the latter half of the subscript indicate the position in the sub-scanning direction. And m × n pieces of recording density data, which similarly consist of ICD ₁₁ to ICD _mn If the image information for one halftone expression pattern is to be obtained, the information of the child matrix pattern CMPij of the halftone expression pattern specified by the print density data ICDij is obtained as the print information of the bit distribution for the print density data ICDij. Claims (1), (2) or (3)
A method for processing digital color image reproduction according to the item. 5. A color image reading means for separating a color image into a plurality of colors and converting the image density into digital data for each color component; a color component data processing means for processing the digital data into color component recording density data. A plurality of sets of halftone expression pattern information consisting of a predetermined number of bits in which recording information bits and non-recording information bits are distributed corresponding to recording densities to be expressed as a whole area are set as one group, and one for each color component. The halftone expression pattern information of each set in the same group, which is associated with the group, is recorded information as the recording density becomes higher in correspondence with the recording density when it is set to the X, Y two-dimensional bit distribution that constitutes the recording area. The bits have a recording information bit distribution that spreads from a predetermined point on the X and Y coordinates, and the predetermined points in each group are at different positions from each other and are divided in each group. Memory means for storing halftone expression pattern information of a plurality of groups, which is a plurality of groups, which is a plurality of points; An area for a plurality of dots of a part of the halftone expression pattern is specified based on the coordinates of the pixels of the original image from which the halftone expression pattern information is specified based on the color component recording density data. Is regularly cut out as a child matrix pattern corresponding to the pixels of the original image, and pattern information reading means for outputting recording and non-recording bit information of the child matrix pattern; and, in response to the output recording bit information, A digital color image reproducing apparatus, comprising: a recording unit for recording a predetermined color on a recording medium at a position to which the recording bit information should be allocated. .