JPS62220072A - Processing method for halftone digital color image - Google Patents

Abstract

PURPOSE:To obtain beautiful halftone image and character image by extracting the component of black from the bits of information of plural fundamental colors, separating a bit of character information before a halftone process, performing the halftone process only on a bit of picture information, and after that, generating a bit of output information by synthesizing both bits of information. CONSTITUTION:A signal BK inputted from a UCR process/black generation circuit 107 is stored once on a buffer memory 127, and is divided into a character data and data other than the character data by a character recognition circuit 121. The data other than the character data is stored at the area of the black BK of a memory 108, and in the recording operation of a copying machine, the data is read out in order from the memory 108, and is halftone- processed at a gradation processing circuit 109, and processed binary data Y1, M1, C1, and BK1 are supplied to laser drivers respectively. The image data of six bits of respective color excluding the character data, is converted to a binary data respectively by the gradation processing circuit 109. Both bits of information are synthesized, then being supplied to the laser drivers respectively.

Description

Detailed Description of the Invention [Field of the Invention] The present invention relates to 1 a halftone digital color image processing method used for reproducing halftone information by dither processing or the like in an image processing apparatus such as a digital copying machine; Regarding.

[Prior Art] In the case of recording an image using the Dra 1 to 6 recording methods, in a normal recording apparatus, the density level of each dot can only be adjusted in about four stages at the most. However, for example, in digital color copying machines, generally yellow (Y), magenta (
M), cyan (C).

Sixty-four levels of gradation expression are required for each basic recording color such as black (BK).

When performing such multi-tone expression, conventionally, a relatively large dot area consisting of multiple dots (for example, 8x8) is used as a unit of gradation processing area, and the number of recorded dots and non-recorded dots are determined for each dot area. The density level of each gradation processing area is expressed by adjusting the number of dots. This type of halftone expression method is called an area gradation method, and known means for realizing it include a dither method, a density pattern method, a submatrix method, and the like.

However, if we use an 8x8 dot area as the unit of gradation processing, for example, it will be 1/1
The recording resolution decreases to 8. For example, in an image such as a photograph, even if the resolution is low, if the intermediate tone, that is, the density of each pixel is accurately expressed, the recording quality will be highly evaluated. However, in the case of characters, a decrease in resolution immediately leads to a decrease in recording quality, which means that the recorded characters are difficult to read.

Therefore, it has been proposed to switch whether or not to perform halftone processing by operating a switch depending on whether or not the document image contains character information. However, in the case of a document containing a mixture of halftone images such as photographs and text information, the recording quality of one of the photographs and text inevitably deteriorates.

[Object of the Invention] The present invention aims to obtain high-quality processing results for both the halftone image and the text information for an input image such as a photograph in which the halftone image and text information are mixed. 1 purpose,
A second purpose is to output character information with higher resolution than input information.

[Structure of the invention] In order to achieve the above object, in the present invention.

Input yellow (Y), magenta (M), cyan (
The black (BK) component is extracted from the information of multiple basic colors such as C), and for this black component information; before performing halftone processing, text information is separated from the input image information, and non-text information is extracted. Halftone processing is performed on the input image information of Output.

According to this, even when processing image information in which single character information and halftone information are mixed, there is no reduction in resolution because the character information is not subjected to halftone processing, and image information other than text information such as photographs is Because it undergoes halftone processing,
Gradations faithful to the input information can be obtained. In other words, a clear halftone image and an easy-to-read character image are reproduced on the same image.

Since text information that requires emphasis on readability is generally recorded in black, information on each color component other than black component information extracted from multiple basic color data is considered not to include text information. It's fine. By limiting the separation of character information and special processing to the separated information only to the black component, the configuration and processing contents of the device that performs this processing can be simplified.

In a preferred embodiment of the present invention, character recognition processing is performed on character information separated from input image information. Then, information on a character pattern (i.e., typeface) assigned in advance to the recognized character is generated for each character, and this generated information is output as character information. In other words, regarding the character information included in the input image information, character information in a predetermined type pattern that is substantially unrelated to the pattern shape of the input information is output.

According to this, when processing input image information obtained from a document including handwritten characters, for example, one handwritten character information is replaced with a printed character pattern, thereby outputting a clean-cut image that is easier to read than the input image.

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

[Example 1 Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows the structural components of a mechanical section of a digital color copying machine of one type that embodies the present invention, and FIG. 2 shows an outline of the configuration of the electrical equipment section.

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 solid-state imaging devices C CD 7 r r 7 g and 7b, respectively. In other words, red light is CO
D 7 r, the green light enters the COD 7g, and the blue light enters the CCD 7b.

The fluorescent lamps 31+32 and the first mirror 41 are connected to the first carriage 8.
The second mirror 42 and the third mirror 1J are mounted on the second
By moving the second carriage 9 at the speed of the first carriage 8, the optical path length from the document 1 to the COD is kept constant, and when reading the original image, the first and second carriages are 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 IO, 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 (original image reading and scanning), backward (return), and the second carriage 9 moves forward and backward by the motor 10 in the forward and reverse directions.
moves at a speed of 172 of the first carriage 8.

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. When the first carriage 8 is driven to the right during exposure scanning and moves away from the home position, the sensor 39 does not receive light (carriage non-detection). When the first carriage 8 returns to the home position, the sensor 39 receives light ( carriage detection)
Therefore, when the state changes from non-light receiving to light receiving, carriage 8
will be stopped.

Referring to FIG. 2, the outputs of the CCDs 7r, 7g+7b are converted from analog to digital and subjected to necessary processing in the image processing unit 100 to produce recorded color information of black (BK) and yellow (Y). , magenta (M), and cyan (C), respectively, are converted into binary signals for recording activation. Each of the binary signals is sent to a laser driver 112bk.

112y, 112m and 1!2c, 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. The emitted laser beam.

1 rotation polygon mirror 13 bk, L 3 y*
It is reflected by L 3 ra and 13c, and is reflected by f-θ lenses 14bk and 14y.

After passing through 14m and 14c, the fourth mirror 15bk.

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

Reflected by L6y, 16m and L6c, polygon mirror surface tilt correction cylindrical lens L 7bk, 17y+17
Through 111 and 17c, photosensitive drum 18bk.

18yw18n+ and 18c are imaged and irradiated.

Rotating polygon trtl 3bk, 13y, 13m and 13c are polygon W/1wA moving t''-') 4 lb
The motors are fixed to rotating shafts of motors k, 41y, 41s, 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.

Further, referring to FIG. 1, the surface of the photoreceptor drum is connected to charge scorotrons 1 9bk, 19y, 19 and 1 connected to a negative voltage high voltage generator (not shown).
It is uniformly charged by 9c. When a laser beam modulated by a recording signal is irradiated onto the uniformly charged surface of the photoreceptor, the charge on the photoreceptor surface flows to the device ground of the drum body and disappears due to the light guide W1 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 parts of the surfaces of the photoreceptor drums 18bk, l8y, 18m and 18c corresponding to the parts with high document density are -soo.
The potential of v is about -100 V at a portion corresponding to a light density part of the original, and an electrostatic latent image is formed corresponding to the density of the original. Each of these static flt latent images.

Black developing unit 20bk, yellow developing unit 20y, magenta developing unit 20m and cyan 11
6 unit 20c, and photosensitive drum 18b.
Black, yellow, magenta and cyan toner images are formed on the surfaces of K, 18y, 18m and 18c, respectively.

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 the toner adheres to the area where the surface potential of the photoreceptor is higher than the developing bias, and the toner is attached to the original. 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 paper feeding operation of the feed roller 23, and transferred to the transfer belt 267 by the registration roller 24 at a predetermined timing.
Sent to 5. The recording paper placed on the transfer belt 25 is
Due to the movement of the transfer belt 25, the photosensitive drums 18bk,
The photoreceptor drums L8bk, L8y,
While passing through L8 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 a thermal fixing unit 36, where the toner is fixed to the recording paper, and the recording paper is discharged to a tray 37.

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

A cleaner unit 21bk and a black developing unit 20bk that collect black toner are connected to a toner collection pipe 42.
The black toner collected by the cleaner unit 21bk is collected by the developing unit 20bk. Note that the cleaner unit 21y is caused by reverse transfer of black toner from the recording paper during transfer to the photoreceptor drum 18y.

The yellow, magenta, and cyan toners collected at 21m and 21c are not collected for reuse because they are mixed with toners from different color developing devices in the preceding stages 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 rotationally driven in a counterclockwise direction by a 1wA moving 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 black 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 shaft 32, and this spring 34 applies a 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, the toner images of each machine are 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 resists the repulsive force of the compression coil spring 34.
rotates counterclockwise, the drive roller descends by 5+ua,
The transfer belt 25 is a photosensitive drum 44y.

44n+ and 44c, photosensitive drum 44bk
remains in contact with. In this state, the transfer belt 2
Since the recording paper on No. 5 only contacts the photoreceptor drum 44bk, only the black 1 to toner images are transferred to the recording paper (black mode). The recording paper is the photosensitive drum 44y, 44
Since the recording paper does not come into contact with the photosensitive drums 44y, 44-, and 44c (residual toner), yellow, magenta, cyan, and other stains do not appear on the recording paper. That is, when copying in the 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.

Referring to FIG. 2, the image processing unit 100 is as follows.

The three color image signals read by CCD7r, 7g and 7b are converted into black (BK) and yellow (Y) necessary for recording.
, magenta (M), and cyan (C) recording signals. Note that the image processing unit lOO is given three color signals from C0D7r, 7g, and 7b as described above in the copying machine mode.

In the graphics mode, three color signals are applied 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, 7B, and 7b into 8 bits, and includes corrections for optical illuminance unevenness, sensitivity variations in internal unit elements of CCDs 7r + 7g, and 7b, etc. to create read color gradation data.

The multiplexer 102 is a multiplexer that selectively outputs either the output gradation data of the correction circuit 101 or the output gradation 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 the 64 gradations will be output. γ
Three-color gradation data of 6 bits indicating each gradation of red (R), green CG) and blue CB) outputted from the correction circuit 103 is provided to a complementary color generation circuit 104.

Complementary color generation is the conversion of the name of each color read signal to the recorded color signal, red (R) gradation data becomes cyan (C) gradation data, and green (G) gradation data becomes magenta (M) gradation data. data and also blue gradation data (B)
is converted (read) as yellow gradation data (Y).

Each data of Y + M − C output from the complementary color generation circuit 104 is provided to a masking processing circuit 106 .

Next, masking processing and UCR processing will be explained. Generally, the calculation formula for masking processing is Yi + Mi, Ci
: Data before masking.

Yo, Mo, C,: data after masking.

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

Therefore, in this example, using these equations, we use the product of both coefficients.

is calculated to find new coefficients. The coefficients (a11'', etc.) of the above calculation formula that simultaneously perform both the masking process and the UCR/black generation process are calculated in advance and substituted into the above calculation formula to obtain the scheduled input Yi of the masking processing circuit 106,
The calculated value (Y
o', etc.: outputs of the UCR processing circuit 107) are stored in the ROM in advance. Therefore, in this embodiment, the masking processing circuit 106 and the UCR processing/black generation circuit are constituted by a set of ROMs, and the data at the address specified by inputs Y, M, and C to the masking processing circuit 10G is UCR. A buffer memory 108 and a character processing port 11fil 2 are used as outputs of the processing/black generation circuit 107.
given to 0.

Generally speaking, the masking processing circuit 106 performs Y,
The tJcR processing circuit corrects the M and C signals, and the tJcR processing circuit performs color balance correction when toners of each color are superimposed. After passing through the UCR processing/black generation circuit 107, Y is input.

Black component data BK is created by combining the three color data of M and C.
is generated, and the output Y, M, and C color component data are as follows:
The value is corrected by subtracting the black component BK.

Y output from the UCR processing/black generation circuit 107.

The M and C data are first stored in storage areas for each color in the buffer memory 108. The black BK data is processed by the character processing circuit 120, and the remaining data after removing the character information contained in the BK data is stored in the buffer memory 1.
It is stored in the BK area of 08.

Y, M, C and BK stored in buffer memory 108
Each 6-bit gradation data is subjected to halftone processing by the gradation processing circuit 109, and is converted into 1-bit binary data Yl for each color.
, Ml, CI and BKI, the laser driver 1
12. Laser driver 1 for black I3
The logical sum BK3 of the output data BKL of the gradation processing circuit 109 and the output data BK2 of the character processing circuit 120 is applied to the input terminal of 12bk.

FIG. 3a shows a schematic configuration of the character processing circuit 120.
Referring to figure a, this circuit 120 is as follows.

Character recognition circuit 121. Dictionary 122. Read-only FIMo+) (ROM) 23. Conversion circuit 124. Buffer memory 125. Shift register 126. Buffer memory 1
It has 27 etc. The dictionary 122 stores characteristic parameters of various characters necessary for character recognition. The memory 123 stores pattern data of various characters.

The operation of the character processing circuit 120 will be explained. The signal BK input from the OCR processing/black generation circuit 107 is stored in the buffer memory 127 and processed by the character recognition circuit 121. The zero character recognition circuit 121 sequentially processes the data stored in the buffer memory 127. First, character data and other data are separated.

In this embodiment, in order to perform the above separation, the horizontal and vertical sizes of each area where black pixels (pixels whose density is at the recording dot level) are continuous are set to predetermined upper and lower limit values (threshold values). The results are compared and it is determined whether the data in that area is a character or not.

That is, each pattern of characters, etc. is generally composed of a continuous area of black pixels, and there are generally blank spaces, or white pixels (with low density), between characters and between characters and other image information. Since there is an area of the recording dot level of the image a>, the size of each area of consecutive black pixels can be regarded as the size of an individual pattern.Also, normally, the size of characters falls within a predetermined range. On the other hand, image information other than characters has no particular size and is often larger than a single character. Therefore, by determining the size of a continuous area of black pixels, it is possible to can identify whether the data is a character or not.

Data that is deemed to be non-character data by the above determination is stored in the black BK area in the buffer memory 108,
Separated from character data. The following processing is performed on the separated character data.

First, individual patterns (characters) are cut out, and each pattern thus obtained is subjected to character recognition processing.

If recognition is successful, a character pattern is generated using the character code obtained by recognition; if recognition is not successful, it is assumed that it is not a character, and the pattern data that was the target of recognition is , memory 108 black BK
Store in the area. This process is performed for all patterns.

In the recording operation of the copying machine, data is sequentially read out from the buffer memory 108, subjected to halftone processing in the gradation processing circuit 109, and processed binary data Yl, Ml, CI
and BKI are respectively applied to the laser driver. Also,
In synchronization with this data output, character pattern data generated within the device for the recognized character is output as a signal BK2.

Signal BK3 given to laser driver 112bk is the logical sum of signals BKI and BK2. However, since the data stored in the buffer memory 108 is only image information excluding character data, the signal BKL becomes a non-recording level (white pixel) at the timing when character data is output.
The level data corresponding to the character pattern is cursed in the signal BK2. That is, in the case of characters, an internally generated printed character pattern is output instead of the input character information, and recording is performed accordingly.

Therefore, for example, if a document on which handwritten characters are recorded is read and copied, the handwritten characters will be replaced with easily readable printed characters on the copy image.

This creates a clean copy.

An outline of the above processing is shown in FIG. 5a.

The 6-bit image data of each color, excluding character data, is converted into binary data by a 1-gradation processing circuit 109, respectively. In this example, the gradation processing circuit 109 includes a read-only memory (ROM) 114y, 1 as shown in FIG. 3b.
14m, 114c, 114bk and digital comparator 11
It consists of 5y, 115s, 115c, and 115bk.

As shown in FIG. 4C, each read-only memory has a 6-bit threshold value at an address corresponding to each pixel position of a matrix consisting of 64 pixels, 8 pixels in the main scanning direction and 8 pixels in the sub-scanning direction. Data is stored.

Therefore, the result of dithering the input data in units of 8 x 8 pixel matrix areas is output from each digital comparator. represents the density of each area), the image data shown in Figure 4b is obtained, and when it is compared with the threshold data shown in Figure 4C, binary data as shown in Figure 4d is obtained. can get.

In addition, in FIG. 4d, the pixels indicated by hatching are at the black pixel level, and the other pixels are at the white pixel level.

When such halftone processing is performed, the rJIIF of the input image is
ll is reflected in the output image, but the resolution is greatly degraded. However, as mentioned above, since halftone processing is not performed for character information, the resolution of a single character does not decrease.For halftone images such as photographs, if the gradation is accurately reproduced, the resolution may be slightly reduced. Even if it does decrease, the overall image quality does not decrease much.

An outline of the "r character recognition" process in step S10 in FIG. 5a is shown in FIG. 5b. This will be explained with reference to FIG. 5b. In this process, first, cut out pattern data is input and isolated pixels are separated. An isolated pixel is a relatively small isolated data area that is not included in a normal character pattern and is made up of one or several black pixels. The data of separated isolated pixels is discarded. However, if the character cannot be recognized in later processing, the data of the isolated pixel is also sent to the memory 108 as image data.

Next, normalize the pattern size. In other words, in handwritten characters, etc., the sizes of each character are often not uniform as shown in FIG. The sizes of the characters in the text do not necessarily match, so the sizes should be made the same to make them easier to recognize. That is, each pattern pTt shown in FIG. 6a, for example, is enlarged or reduced.

PT2 and PT3 are each pattern P of FIG. 6b.
Convert to TIB, PT2B and P73B.

In this case, data on the magnification of enlargement or reduction and data on the position of the input pattern are saved for later reproduction of the characters.

Next, smoothing processing is performed. For example, areas Pa and Pb (splashes) of the character pattern shown in FIG. 7a are removed because they interfere with single character recognition, and smoothed as shown in FIG. 7b.

Now that the preprocessing is complete, we move on to the first feature extraction.

First, feature extraction in the opening direction is performed. Specifically, Section 8a
As shown in the figure, the pixel oj above the pixel of interest DO, the pixel D2 . Downward pixel D3 and leftward pixel D4 (
The 8th cI! Fifteen types of open direction codes as shown in 1 are assigned, and these open direction codes are attached to the pixel of interest. Note that the pixel arrangement shown in FIG. 8a is generally called a nearest neighbor pattern.

For example, when an open direction code is given to a group of pixel data obtained from the input image PTC corresponding to the area ARX as shown in FIG. 9a, an open direction code arrangement as shown in No. 90@ is obtained.

Next, pixels adjacent to each other with the same opening direction code are classified as one group (connected head).For example, in FIG. 9b, the areas ARI, ARB,
It is classified into AR4, AR5, AR7 and ARB. Further, regarding the area ARB, there are cases where it is separated into one area and cases where it is separated into two areas depending on a slight change in the length of the stroke of the character pattern.

Regarding this, two areas ARB are shown in FIG. 9C.
Forcibly separate into ARB a and ARB b. Furthermore.

Noise components are removed from the obtained feature data.

The noise component in this case refers to a particularly small area and a particularly small width compared to a jujube. Finally, the barycentric coordinates of each region (ARI, ARB, ^R5, . . . ) are determined, and the feature extraction in the opening direction is completed.

Next, stroke features are extracted.

First, a direction code is given to each pixel using a 3.times.3 pixel pattern (generally called a next-neighbor pattern) shown in FIG. 8b. Here, different direction codes are given to each of eight types of directions, as shown in FIG. 8d. The relationship between the various combinations of pixel arrays in a 3x3 pixel pattern and the direction code is as shown in Figure 8e (there are 256 types in total).As a result, data as shown in Figure 10g is obtained, for example. It will be done. 9 is an undefined code.

Next, in order to clarify the characteristics of directions, the eight types of direction codes are integrated into four types. Specifically, even code 2, 4
．． Replace 6 and 8 with the most likely code in the direction adjacent to them. That is.

For an even code 2n, the number of odd codes 2n+1 and the number of odd codes 2n-1 in the adjacent pixels are counted, and vl is replaced by the direction code with the larger number. If it cannot be decided, give an undecided code 9.

Integrating the direction codes in Figure 10a yields the result in Figure 1Qb. The undetermined code 9 is finally converted into one of the direction codes 1, 3.5, and 7. No. tob
Processing the orientation code in the figure yields the result in Figure 10c.

Further, adjacent pixels to which the same direction code is attached are each classified as one region, and the class coordinates and length of each region (stroke) are determined, and these together with the direction code are used as feature data.

Subsequently, the feature data obtained through the above processing, that is, the stroke information, is compared with the data stored in the dictionary 122 to find characters with similar feature parameters.

An outline of the "r character pattern generation" process in step S12 in FIG. 5a is shown in FIG. 5C. Note that this process is performed by the conversion circuit 1
24, and will be explained with reference to FIG. 5c. In this process, the character code recognized by the character recognition circuit 121 is input, and the radical code and stroke code corresponding to the code are input from the ROM 123. For each radical code, the corresponding stroke code data is stored in the ROM12.
3, and generates "decoration" pattern data according to the connection state of the strokes. Then, for each stroke code, the pattern data is stored in the ROM 12.
3 and performs the "pattern data generation" process, and these processes are performed for all strokes and all radicals. Once the process is finished.

The generated pattern data is stored in the buffer memory 125.

Note that the "r decoration" includes, for example, "r" attached to the character pattern shown in FIG. 11, "presser foot", and "shoulder".

``Hane'', etc.

“Generate pattern data” in step 5128 of FIG. 5c.
The process (enlargement process) is specifically the process shown in FIG. 5d. This will be explained with reference to FIG. 5d. First, a reference position for arranging the pattern is determined. This is determined based on the reference position data of each character pattern information input to the character recognition circuit and the offset amount of the reference position of the stroke in the pattern.

Next, the offset amounts (0 to NWi elements) of the X and Y coordinates with respect to the reference position are sequentially updated pixel by pixel, and the pattern data obtained from the ROM 123 for each coordinate is written into the output data bitmap. As a result, data writing is repeated NXN times while updating the coordinates, and pattern data N times the size of the pattern data stored in the ROM 123 is obtained.

Note that in the above embodiment, dither processing is performed as halftone processing, but the density pattern method is used.

Halftone processing may be performed using a submatrix method or the like.

[Effects] As described above, according to the present invention, a halftone image can be reproduced without reducing the resolution of character information.

Particularly, when performing character recognition as in the embodiment and replacing input character pattern data with type pattern data generated within the device, handwritten characters and the like can be automatically transcribed.

[Brief explanation of drawings]

FIG. 1 is a front view of the interior of one type of copying machine embodying the present invention. FIG. 2 is a block diagram showing the electrical circuit configuration of the device shown in FIG. 1. 3a and 3b are block diagrams showing the configuration of a part of the circuit shown in FIG. 2. FIG. FIGS. 4a, 4b, 4c, and 4d are plan views showing examples of input images, input multi-value data, threshold data, and data after halftone processing, respectively. 5a, 5b, 5c, and 5d are flowcharts outlining the processing method in the apparatus of FIG. 1. 6a, 6b, 7a, 7b, and 11 are plan views showing examples of character patterns. Figures 8a, 8b, 8c and 8e. FIG. 3 is a plan view showing an example of a pixel arrangement. FIG. 8d is a plan view showing the relationship between directions and direction codes. Figures 9a, 9b, 9c, and 10a. 10b and 10c are plan views showing examples of pixel arrays. 107: OCR processing/black separation circuit 108.125, 127: Buffer memory 109: Gradation processing circuit (halftone processing means) 11O Nior gate 120: Character processing circuit 121: Character recognition circuit 122: Dictionary 123: Reading/writing only memory

Claims (4)

[Claims] (1) A halftone digital color image processing method for an image processing device that includes a halftone processing means that expresses the gradation of input image information using a plurality of output pixels, and processes input image information of a plurality of basic colors. In: extracting black component information from input information of a plurality of basic colors, separating text information from input image information before performing halftone processing on the black component information, and separating text information from input image information other than text information; It is characterized by performing halftone processing on information, prohibiting halftone processing on text information, and outputting information obtained by combining halftone processed image information and information corresponding to the separated text information. , Halftone digital color image processing method. (2) Perform character recognition on the separated input character information, generate information on a character pattern assigned in advance to the recognized character, and output information on this character pattern instead of the input character information. and combining it with the halftoned image information.
1) The halftone digital color image processing method described in item 1). (3) The halftone digital color image processing method according to claim (1), wherein text information and other information are separated by determining the size of each area where recording level pixels are continuous. . (4) As a result of character recognition processing, information that cannot be recognized as characters is subjected to halftone processing, as described in claim 1, (2), or (3) above. Halftone digital color image processing method.