JPH0332281A - Color picture processor - Google Patents

Abstract

PURPOSE:To enable picture processing with high definition suitable for the various kinds of pictures by discriminating mixed pictures for each primary color picture signal and executing color reproducing processing respectively variously for character pictures and gradation pictures based on a result occupying the large number of these discrimiated results. CONSTITUTION:After density conversion, digital picture signals are supplied to discriminating circuits 21-23 constituting a mixed picture discriminating means. Picture discrimination outputs to be obtained in these circuits are supplied to a color reproducing part 17 with the discriminated result occupying the large number in a majority circuit 24 as the final deciding signal. Namely, when the character picture is discriminated, the deciding signal is made '0' and a color reproducing table for character picture in the color reproducing part 17 is selected. When the gradation signal is discriminated, the deciding signal is made '1' and a color reproducing table for both character and gradation in the color reproducing part 17 is selected. Thus, since character picture processing and gradation picture processing are respectively selected even when the character picture and gradation picture are mixed on the same original, picture output quality is maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a color image processing device suitable for a digital copying machine. The present invention relates to an excellent color image processing device.

(Background of the Invention) Generally, in an electrophotographic digital copying machine,
The image information (original image) of the original is divided into minute peak elements of approximately several tens of microns, the electric signal (image signal) corresponding to the density of each pixel is converted into a digital signal, and the digital image signal is processed internally. After converting, the image is output to a recording device such as a laser, and a copy image is obtained through an electrophotographic process.

In such digital copying apparatuses, internal signal processing is often changed depending on the type of input image.

For example, when the human image is a so-called general document such as a book or a letter, the density of the characters and the color level of the background are not so important, and it is desired that the characters be reproduced sharply.

Therefore, in the case of a printer that outputs only two values (on and off), the image is reproduced by converting human image information into two values at a certain level. In the case of a printer capable of FiJ multi-value recording according to density, character images can be clearly reproduced by controlling with emphasis on reproduction time and black output.

On the other hand, when a human image has so-called gradation, such as a photographic image, reproduction of intermediate tones becomes important, which is different from when the purpose of processing is mainly text.

For example, in the case of a binary printer, a pseudo halftone image is formed using a well-known method such as a dither method or a density matrix method, and the image is reproduced using the output thereof. Even in the case of multilevel printers, the output characteristics are often designed to emphasize the reproduction of halftones.

In addition, especially in these processes, the mesh line side, which is often used for newspapers, etc., requires special processing. The mesh line side is made up of many dots, and when viewed microscopically, there are certainly no midtone areas and it resembles a character image.

However, since the original purpose of the halftone line is to reproduce pseudo-halftones using dots of different sizes, it is often easier to see the output if it is reproduced as an image with the same gradations as a photographic image. Furthermore, a certain number of wires for mesh lines is very close to the sampling pitch used in the two-dimensional reading system and writing system of digital copying machines that are currently widely used.

For example, when the sampling pitch is 16 doL/+yun, which is 1 degree, and the number of mesh lines is 1331 ine/1 nch, the number of mesh lines is quite close to the sampling pitch.

Under such conditions, an aliasing error occurs in sampling, which appears as a so-called moiré image, resulting in a significantly deteriorated rigidity. Moiré appears particularly clearly when the original image is binarized, but even when pseudo-intermediate representation such as the dither method is used, the IH appearance frequency only decreases and does not disappear completely.

As a countermeasure to this problem, it is possible to reduce the high frequency components of the original image to reduce interference with the sampling pitch. Specifically, -C smoothing may be performed using surrounding pixel topography.

As described above, by switching the coefficients for image processing and multi-value conversion according to the characteristics of each image, the output image can be maintained at a high quality. Normally, these switching is performed by the operator himself by switching the processing mode depending on the document.

However, when copying a document that has different features such as text and photos in one image, such as a pamphlet, if text and image processing is set, the reproducibility of the photo part will be lost, etc. I can't get a satisfactory copy either way. Therefore, the overall copy quality is not good.

To solve this problem, it is sufficient to determine whether the human image information is a character image or a gradation image, and to switch the processing based on the determination result.

Conventionally, the so-called block-by-block discrimination method, which divides the original image into several small blocks and switches processing based on the discrimination results for each block, has been used as a means of discriminating whether it is a character image or a gradation image. ``Binarization processing method for manuscripts containing both value images and gray images'' (IEICE Transactions VOL,
J[17-B No. 7 (1984) pp781-
788) and the so-called 1' pixel-by-pixel separation method in which processing is performed at the middle of each pixel, even if information from surrounding pixels is taken in; for example, the technique described in Jikai I+/I62-i-04372. It has been known.

(Problem to be Solved by the Invention) Of the above-mentioned 1-discrimination means, discrimination is performed for each block.
1'11 alternative methods include, for example, a method of checking the density dispersion within the block of interest and determining that it is a character stroke if the dispersion is large. According to this discrimination method, if a block is incorrectly classified, all the blocks will be processed incorrectly, resulting in a severe deterioration in quality.

In addition, in general, block-by-block discrimination requires more memory to temporarily store ii'liii image data than pixel-by-pixel discrimination, which is expensive and has the disadvantage that the signal processing is also complicated. There is.

On the other hand, the pixel-by-pixel discrimination method has the advantage of having fewer side effects due to misidentification and requiring relatively little memory, but this method cannot detect clearly printed characters or photographic images. It was for the purpose of identification.

Therefore, no process has yet been proposed that automatically discriminates even characters with shading, such as halftone lines and general handwritten characters, and applies optimal image processing to each character.

Furthermore, no image processing apparatus has been proposed that takes into account accurate 1'11 separation and accurate reproduction of characters other than black and gradation side 1, such as chromatic character images and halftone lines.

For example, if there is a chromatic color image, which color should be mixed 71E?
The problem is how to distinguish between images. In addition, if multiple colors are mixed [when performing image discrimination, the results vary,
Another issue is how to make a break.

Therefore, if a mistake is made in such a case, inappropriate image processing will be performed, resulting in a disadvantage that the quality after image processing will be significantly degraded.

The present invention has been made in view of the above-mentioned problems, and its purpose is to accurately distinguish between text and two-tone pictures, regardless of whether they are achromatic or chromatic, and to The present invention aims to realize a color image processing device that can perform high-quality color image processing suitable for the characteristics of an image.

(Means for Solving the Problems) The present invention solves the above-mentioned problems by using a color reproduction table for converting primary color and dual image signals obtained by scanning a document into color signals for image recording. For both the key side and the key side,
A color reproduction means for performing color reproduction using one of the color reproduction tables based on a judgment signal given from the outside, and a mixed side discrimination means for discriminating the original image into a gradation side and a character image for each primary color image signal. , and a majority decision means for supplying a majority of the results of discrimination for each primary color image signal by the separate means as a constant signal to the color reproduction means.

(Operation) In the color image processing apparatus of the present invention, mixed side determination is performed for each primary color image signal. Then, based on the majority of these discrimination results, the character image color reproduction table or the gradation image color reproduction table is selectively used to perform color reproduction processing.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing a schematic configuration of an embodiment of the present invention. The outline of the color image processing apparatus will be explained with reference to FIG.

In this figure, 1 is a document, 2 and 3 are dichroic mirrors for separating the image information (optical image) of the document into R, G, and B, respectively, and 4, 5.6 are R, G, and B, respectively.
CC for obtaining primary color image signals by photoelectrically converting the optical image of
D, 7, 8.9 are A/D converters that A/D convert the primary color image signals of R, G, and B to generate digital image signals, and 10° and 11.12 are the A/D converters for R, G, and B, respectively. A shading correction circuit that corrects shading of a digital image signal, i, 3, 14.15 are R and G, respectively.

A gate circuit extracts only the effective width from the B digital image signal, 16 is a density conversion circuit that converts the density of the R, G, and B digital image signals, and 17 converts the R2G, B digital image signal to Y, M, C, This is a color reproduction section for converting (color reproduction) into a color signal for recording a K image.

The color reproduction section 17 has a plurality of independent color reproduction tables therein, and one of them is selected according to an image discrimination signal from the outside to perform color reproduction processing. That is, the color reproduction section 17 has color reproduction tables for each of Y, M, C, and K for character images and gradation images. 18 is a selector that selectively passes the Y, M, C, and K digital color signals from the color reproduction section 1-7 in accordance with image formation; ]9 is a selector that performs multi-value processing on the digital color signals to produce multi-value data; The multi-value conversion channel 2 [] is a printer unit (2) that receives the multi-value data and outputs a color image as a hard copy by sequentially overlapping toner images of each color of Y, M, C, and K. image output device). 21 is the determination of a character image and one gradation image from the R image signal (
A discriminating circuit 22 discriminates between 1' and 1st gradation of character images from the image signal of G, and an open circuit 23 of II separates 9 gradation images of character images from the image signal of I3. There are n fil-separate circuits that perform the discrimination. These !r-separate circuits 21 to 23 constitute the mixed image discrimination means. 24 is a majority decision circuit that constitutes the majority decision means. This majority decision circuit 24 is ' This is for supplying the majority of the determination results of the I'll classification circuits 21, 22, and 23 to the color reproduction section 17 as a final determination signal.

The operation of the apparatus of this embodiment will be explained below.

The color image information (optical image) of original 1 is stored in two dichroic
The image is separated into three color-separated images in the f-sink mirrors 2 and 3. In this example, the image is separated into a red R color separation image, a green G color separation image, and a blue B color separation image.

Therefore, the cutoff wavelength of the dichroic mirror 2 is about 450 to 5200 nm, and the cutoff wavelength of the dichroic mirror 3 is about 550 to 620 nm.This allows the green component to pass through. The blue component becomes the first reflected light, and the red component becomes the second reflected light.

The color separated images of red, R, green, and blue B are supplied to image reading means, such as CCD sensors 4, 5.6, and primary color image signals of only the red component, R2, G, and blue component are output from each image reading means, for example, CCD sensors 4, 5.6.

Both primary color image signals R, G, and B are sent to A/D converters 7 and 8°9.
A predetermined number of bits, in this example 8
It is converted into a digital image signal of the pit. And A
Shading correction is performed simultaneously with /D conversion.

After the shading-corrected digital two-image signals are extracted by gate circuits 1.3 and 14.15, only the signal corresponding to the width of the maximum original size is extracted, and then density conversion is performed in accordance with human viewing characteristics. When the maximum document width to be handled is A3 size, the gate signal is a size signal A generated by a timing signal type 1 means (not shown) of the system.
3 is used.

Here, assuming that the R, G, and B digital image signals subjected to the -C1 density conversion are VRVG and VB, respectively, these digital image signals VR, VG, and VB are supplied to the color reproduction section 17 and the Y of the printer unit 1-20111. M,
It is converted into C and K color signals.

In this example, image form 1 on printer unit 20 is The recording colors are Y (yellow) and 1M (magenta).

A case is illustrated in which the colors are C (cyan) and K (black).

The color reproduction unit 17 is a color reproduction table (lookup table) configured in ROM, and includes a character image color reproduction table suitable for processing character images and a gradation image suitable for processing gradation images. Color reproduction table for Y, M, C, K
Each has one. That is, in this embodiment, the color reproduction section 1
．． The storage area of 7 (ROM) is divided into two blocks, and each block stores Y data for color reproduction.
, M, C.

It is stored for each K.

The color reproduction table for text and drawings focuses on clearly reproducing text, etc., and stores data that forces delicate pale hues and colors close to achromatic colors to be expressed in white/black. This is a reproduction table.

In addition, the color reproduction table for gradation drawings is a color reproduction table that stores data that places emphasis on faithfully reproducing the original image, and expresses subtle pale hues and colors close to achromatic colors as much as possible. be.

Selection of these color reproduction tables is based on a determination signal from the majority decision concave path 23. That is, the determination signal is I as the most significant bit of the address of the ROM forming the color reproduction table.
This is how the color reproduction table for both gradation and text is cut. That is, when a character image and a gradation image are mixed in one document image, the color reproduction table selected by the trimming signal performs color reproduction processing suitable for each image. This color reproduction process uses digital image signals VR, VG, and VB as Y,
It outputs M, C, and K color signals (a degree data). Note that generation of this image discrimination signal, majority decision processing, and color reproduction processing based on the discrimination results will be described later.

In this way, YM generated by 1.2 color reproduction processing,
The C and K density data are supplied to the selector 18. A scan code (a color code for forming a toner image in the printer unit 20) is sent to the selector 18 by a CPU (not shown), and density blocks according to this scan code are sequentially and selectively passed through. Then, this density data is subjected to multi-value processing in printer unit I/20 so as to be suitable for image formation. The multi-value data for which multi-value processing has been completed in this manner is supplied to the printer unit 1-20, where image formation is performed. In this printer unit 20, toner images of four colors Y, M, and C are sequentially superimposed, so image reading to color reproduction is also performed four times.

In addition, the digital image signal after density conversion is a mixed image 'I'.
The discriminating circuit 2], , 22, 23 which also constitutes a discriminating means. As a result, the image discrimination outputs subjected to 1AI (in this example, each is 1-bit data) are sent to the majority decision circuit 24, and the discrimination results that account for the majority are supplied to the color reproduction section 17 as the final judgment signal.

That is, the color reproduction tables for both the character image and gradation described above are selectively used according to the image content by outputting the image 1' (1111) separately.

In other words, when it is determined that it is a character stroke, the determination signal is
[]", and the color reproduction table for characters and images in the color reproduction unit 17 is selected, and when it is determined that both gradations are used, the determination signal becomes "1" and the color reproduction table for text and images in the color reproduction unit 17 is selected. A color reproduction table will be selected.

Therefore, even if both character image processing and gradation image processing are selected in the same original document, character image processing and gradation image processing are each selected, so that the image output quality is maintained.

For example, in the case of a color calendar, some parts are all gradation and some other parts are all character images. In such a case, if the discrimination results for each color (R, G, B) are used independently, if it is determined that there are two gradations of a certain color, there is a possibility that the tone will be discontinuous in the vicinity. . However, as in this embodiment, if a majority vote is taken for the determination results, no error will occur in the final 1' result. Therefore, problems such as color tone discontinuity do not occur. Also,
Since there are almost no cases where only one specific color has both gradations, problems caused by majority voting do not occur.

Here, the discrimination circuits 21, 22, and 23 will be explained in detail. Furthermore, since each discrimination circuit has the same configuration,
Taking the discrimination circuit 21 as an example, it will be explained with reference to FIG. The above-mentioned discrimination circuit 21 includes first and second 111 different means 3.
It is composed of 0.40.

That is, the first discrimination means 30 is a means for roughly discriminating the input image into both a character image and a gradation, and obtaining a separate output for the first image 1'. On the other hand, the second discriminating means 40 to which the first image discriminating output is supplied re-classifies the image discriminating outputs of both gradations included in the first image discriminating output corresponding to character images by 1'11, This is a means for obtaining the second image discrimination t13 power related to both character strokes and gradation.

Here, the first determining means 30 will be explained in detail.

The first determining means 30 uses a low-pass filter 31 for the pixel of interest and a low-pass output for the pixel of interest to a reference value RE.
It is composed of a comparator 32 that compares with F, and a level determination circuit 33 that further sets the comparison output regarding one pixel to level 1.

The purpose of the low-pass filter 31 is to reduce the high-frequency components of the human image signal, thereby making it possible to roughly distinguish between character images, gradations, and "-6".

When the high frequency components of the input image information are reduced, when the human image is a photographic image or a halftone drawing, the density of the pixel of interest is dispersed to each point, so that every pixel exhibits a certain density Na or higher.

As an example of a halftone image, as shown in FIG. 3(A), the difference in density between dots and non-dots clearly appears.

When this is passed through a low-pass filter 31 to reduce high frequency components, a signal (approximate to a sine wave) corresponding to the repeating pitch of the halftone line drawing is generated at a DC level Na' above a certain level Na, as shown in (13) in the same figure. are obtained by superimposing.

On the other hand, even when the character images and lines are passed through the low-pass filter 31, since there are many background parts, regions with a density lower than that of Na remain.

Therefore, the comparator 32 determines the density of the pixel of interest using a reference value REF having a predetermined level that is less than or equal to Na.

This reference value REF is considerably lower than the threshold value used when converting character strokes to second position, and is slightly lower than the background level at 7:i.

must be set to a new value. If it is too low, it will be difficult to distinguish the background (ground) from one novel, and if it is too high, this reference value RE
This is because there will be cases where the value is lower than that, resulting in misclassification.

Therefore, it is preferable to read the manuscript in advance so that it is possible to
It is better to set the reference value REF after detecting the background level in combination with a so-called automatic density adjustment function that determines the novel.

In the case of both sides of the photo or the halftone line side, the comparison output will be "1",
In the case of character drawings or line drawings, it is "0".

Next, in the level determination circuit 33, the comparison output obtained from the comparator 32 is re-determined.

This re-judgment process is performed only when a check window of a certain size is set up around the pixel, and all pixels residing within that window are equal to or higher than the reference value REF mentioned above. The pixel of interest is determined to be a gradation image.

As a result of this processing, the density is widely dispersed in the case of halftone lines, so that the image is determined as a gradation image.

On the other hand, even if character images are dispersed by the background, etc., a value lower than the reference value remains, and since a portion of the check window is covered by this portion, the pixel of interest is determined to be a character image as expected.

FIG. 4 shows an example of the low-pass filter 31, and in this example, a 3×3 convolution filter configured in a cross shape is used.

The convolution filter used as a low-pass filter is a process that returns the pixel of interest al and its surrounding pixels to the original pixel of interest by applying a certain weight C0.In this example, the pixel of interest and the pixels above, below, left, and right are simply In addition, it is divided by 5 and averaged.

Therefore, the filtered output a'1. of the pixel of interest a. is a', = (1-15)*Σ(C+1*a+1
).

Here, C,l is 1 only for the pixel of interest and the four pixels on the bottom left and right.
The other diagonal acid content is 0.

Here, a cross-shaped type with a weight of 1 was adopted as the low-pass filter 31 for the following reasons.
(Zuku.

One stumbling block is the size of the filter; the larger the filter size, the more dispersed the results will be, making it possible to handle even coarse dots. However, since the overall density level at that time gradually decreases, it becomes difficult to determine the threshold value, and misjudgment becomes more likely to occur. Additionally, as the filter size increases, hardware constraints also increase.

For this reason, in this example, the size is set to 3×3, taking into consideration hardware constraints.

The reason why the filter shape is made into a cross shape will be explained with reference to FIG.

In this figure, the central part is a mesh line dot, and the diagonal lines are a mesh line pattern. Also, a collection of small dots is the minimum unit of reading.

Generally, in the case of the mesh line side, the mesh lines are often arranged in a 45 degree direction. In the case of a cross shape, the result of filtering spreads nicely into a diamond shape along the mesh structure as shown in FIG. 5(B). Therefore, no matter which pixel a window is placed on, there is no extremely low part, and the window is determined to be on the halftone line side as expected.

1 0 On the other hand, if we use an X-shaped dispersion filter (6th
If Figure 6(A)) is used, as shown in Figure 6(B), when the mesh lines are fine, the dots and circles of the adjacent mesh lines will be averaged in a certain area, resulting in a considerably high density. On the other hand, the filter action does not reach the valleys of the X-shape, so the density in these valleys remains low.

Therefore, if a part of the window falls over this valley, this part falls below the reference value, and the pixel of interest is incorrectly determined to be not a gradation image. This occurs regardless of the shape of the window.

From the above, it can be seen that a cross shape is appropriate for the filter shape 17.

Further, in order to distribute the dots evenly, it is desirable that the coefficients of each filter are all 1 (ie, equal).

It is expected that this low-pass filter 31 will effectively disperse even the mesh lines, which are actually quite coarse.

It should be noted that the window for determining extremely small dots or on the side of coarse mesh lines is set to an integer m larger than n, and has a structure extending by n1 pixels on the top, bottom, left and right sides.

FIG. 10 shows a specific example of the bottom of the level 'I'l+constant circuit 33. Since the level determination circuit 33 is also a window groove bottom, it is basically the same as the filter configuration shown in FIG. (
! ], L, Since the human input to the level judgment circuit 33 is the judgment output of the low-pass filter 31, it is a 1-bit signal indicating whether it is a character image or a gradation image.

However, the number of windows used in the level judgment circuit 33 is 7.
Since the size is 7×7, it is necessary to delay by 7 lines and 7 pixels. Therefore, it is used, but only more.

33a to 33f are latch circuits for IH delay;
g is a memory for 7 lines. and 33h-33j
, 33r to 33t are latch circuits for delaying by four pixels.

Although these latch circuits each consist of four latch circuits connected in series, they are shown as one latch circuit for convenience in the drawings. 33 to '33q indicate a latch circuit for one pixel.

If these digital image signals of the 7th and
The digital image signals of each pixel corresponding to the window shown in the figure are 111 temporally simultaneously.

Therefore, when the corresponding digital image signals are ANDed in the AND circuit 3311, the pixel of interest becomes "1-" only when the density level of all pixels is equal to or higher than the reference value. obtained at the output terminal -r-.

In this way, the first discriminating means 30 distinguishes between the literary talent group,
A first image discrimination output corresponding to both the photographic image and the halftone line group is obtained.

By the way, under certain conditions, a character image may be recognized as a character image or as a gradation image.

For example, as shown in Figure 11 (A), when the character image ``Sono'' is a human-powered image, if it is passed through a low-pass filter 1, it will be output as shown in Figure 11 (B). . In other words, it can be seen that when a character becomes smaller than a certain level, the inside of the character becomes considerably blurred due to the effect of the low-pass filter.

At this time, if there is a pixel of interest inside the character, and all of the pixels in its vicinity exceed the reference density due to this filter effect, the pixel of interest will be processed as a pixel of a gradation image. As a result, even if the two images are recognized as character images, as shown in FIG. 12, for example, there are parts inside the character that are erroneously determined to be gradation images.

In this way, the inside of a small character may be misidentified as a gradation image, and as a result, the quality of the character may deteriorate significantly.

Here, i
Since the cutting portion occupies a certain area, such gradation images are not actually scattered in the partial portion. In other words, when a discrimination result in which gradation images are scattered in a very small area is obtained, there are actually no gradation images for each small area, so the ' It can be determined that the result of I'11 is incorrect.

Therefore, as shown in FIG. 2, a second discriminating means 4 [] is provided. This second discrimination means 40 re-discriminates the gradation picture included in the above-mentioned character picture as a character picture.

In order to re-recognize a gradation image included in a character image as a character image, check the area for each gradation image and check if it occupies a certain size. BaJ
:stomach.

To do this, it is sufficient to memorize the image data of a certain region for the pixel of interest, and calculate the table or area of the closed region of the gradation image discrimination portion.

In principle, to execute this discrimination process, it is necessary to store image data in both the main scanning direction and the sub-scanning direction, but in the example described below, due to the limitations of pigeons, it is only possible to perform this in the main scanning direction. There is.

As a result, it is sufficient that the memory has a maximum capacity of one bit indicating whether the image is a character image or a gradation image and one line of memory. Further, it has been found through experiments that the correction jE effect is sufficient even when the main scanning alone is used.

FIG. 13 shows a second discriminating means 40 that achieves such processing.
An example is shown below.

The first image discrimination output output from the first discrimination means 30 is supplied to the input terminal.

As mentioned above, the first image discrimination output is 11 when it is on the gradation side.
The output is "0" when it is a character stroke.

A counter 40a counts the length of the first image discrimination output on the gradation side. Therefore, this counter 40a is set at "1" and reset at "0", and is counted up in synchronization with the dot clock CK. The counter output a is compared in a comparator 40b with a reference value related to the reference length L (FIG. 14(A)).

L should be around 2ml11.

The pulse comparison output exceeding the reference value becomes "1-", and at this time a single control pulse is output from the pulse generating means 40d (FIG. 14(B)).

On the other hand, the dot clock CK is also supplied to the address counter 1 40e to form a horizontal address.
The address data is latched in latch circuit 40f. The latch pulse is a rising output for the first image tll.
The second is formed based on the edge.

40g shows this rising edge detection circuit.

One of the address data of the address counter 40e and the rising address data latched by the latch circuit 40f is selected by the address selector 40h by a control pulse. In this example, it is assumed that the latched address data is selected when the control pulse is obtained. Address data selected by address selector 40h is supplied to first line memory 40i.

A control pulse is supplied to the first line memory 401 as a write enable pulse. Therefore, when the control pulse is obtained, data "1" at a predetermined level is written at the latched address in synchronization with the rising point 0 of the first image tllll force output.

2. On the other hand, in the second line memory 40j, the first image discrimination output is written to the address obtained from the address counter 40e in synchronization with the dot clock CK (see FIG. 14).
C)).

Data is read from the line memories 40i and 40j as shown in FIG. 115. That is, in the next line 11, data is simultaneously read from the line memories 40i and 40j (FIGS. 15(A) to 15(C)).

The output of the line memory 40i passes through a NAND circuit 40k
It is supplied to the set terminal S of the 8-type flip-flop 40n. Similarly, the outputs of the line memories 4Di and 40j are supplied to a NAND circuit 4011 that does not require human input, and the output is further passed through a NAND circuit 40m to a flip-flop 4.
0n reset terminal R.

As a result, a second image discrimination output as shown in FIG. 15(D) is obtained at the output terminal 40o.

When the second discriminating means 40 is configured in this way, as shown in FIG. Only when the value is equal to or larger than L, the final image discrimination output can be set at ``1 degree'' between both images 1' indicating the gradation side.

Therefore, if it is less than a predetermined length, even if it is determined to be on the gradation side, it will ultimately be re-identified as a character stroke (FIG. 15).

Here, the majority circuit 24 will be explained. Since this embodiment has three sets of discrimination circuits, it may be configured to output results from two or more sets with priority. For example, an OR gate receiving the output of the discrimination circuits 21 and 22,
．． OR gate receiving the output of 23, discrimination circuit 21.23
The above-mentioned majority circuit can be configured with an OR gate that receives the output of , and 3 AND gates that receive the outputs of these three sets of OR gates. Note that various other modifications are possible.

As a result of this configuration, manual manuscripts can be processed according to t and II with precision and efficiency that could not be obtained in the past.

4 In the above example, only the lengths of both gradation parts were evaluated and the judgment was made, but a correction circuit that similarly judges an extremely short character part to be misclassified is further provided, and 'I'll' You may modify the results to bring them closer to reality.

Next, an example of a mechanical section of a digital copying apparatus to which the double image processing apparatus of this embodiment is applied will be explained with reference to FIG.

Here, the description will be made assuming that the copying machine uses a color dry development method. In this example, two-component non-contact development and reversal development are employed. That is, the transfer drum used in conventional color image formation is not used, and the images are superimposed on the electrophotographic photosensitive drum that forms the image. Also,
In the following example, in order to reduce the size of the apparatus, yellow Y, magenta M
.

An example will be described in which a four-color image of cyan C and black is developed by rotating the drum four times, and after development, transfer is performed once and transferred to recording paper such as plain paper.

Turn on the copy button (not shown) on the control panel of the copier 5 As a result, the document reading section A is driven.

The original 1.01 on the original table 128 is then optically scanned by the optical system.

This optical system includes a carriage 132 provided with a light 7 such as a halogen lamp, a mirror 131, and a mirror 131.
It is composed of a movable mirror unit 134 provided with mirrors 133 and 133'.

The carriage 132 and the movable unit 1-134 are caused to travel on the slide rail 136 at predetermined speeds and directions, respectively, by a stepping motor.

The optical information (both image information) obtained by irradiating the original 10 with the light source 129 or the reflecting mirror 131 Mirror 133,1
33', optical path Y: information conversion unit l-1, 37
guided by.

A standard white plate is provided on the back side of the left end of the document table (platen glass) 128. This is because the image signal is normalized to a white signal by optically scanning the semi-white plate.

The optical information conversion unit +-137 includes a lens 139, a prism 140, and two dichroic mirrors 102'.
, 103 and the CCD 10 on which the red color angle lb image is captured.
4, a CCD 105 for capturing a red color-separated image, and a CCD 106 for capturing a blue color-separated image.

The optical signals obtained by the optical system are collected by a lens 139, and separated by color angle q into blue optical information and yellow optical information by the dichroic mirror 102 provided in the prism 140 described above. Furthermore, dichroic mirror 10
3, yellow optical information is color separated into red optical information and green optical information.

In this manner, the color optical image is decomposed into three-color optical information of red, R, green, and blue B by the prism 1-40.

By forming each color separated image on the light receiving surface of each CCD, an image signal converted into an electric signal is obtained.

After the image signal is processed by a signal processing system, recording image signals of each color are output to the writing section B.

As described above, the signal processing system includes various signal processing circuits such as an A/D converter, a color reproduction table, and a multi-value processing section.

Writing section B (printer unit:-21,) is deflected 2:
(141) As the deflector 141, in addition to a galvanometer mirror, a rotating polygon mirror, or the like, a deflector made of an optical deflector using crystal or the like may be used.

The laser beam modulated by the color signal passes through this deflector 14.
1 for deflection scanning.

When the deflection scan starts, a laser beam index sensor (not shown) detects the beam 18 scan, and
Beam modulation using a first color signal (for example, a yellow signal) is started. The modulated beam is caused to scan by a charger 154 over the image forming member (photosensitive drum) 142 which is charged in a negative manner.

Here, the main scanning by the laser beam and the image form 1 body 14 are performed.
2, an electrostatic latent image corresponding to the first color signal is formed on the image forming member 421.

This electrostatic latent image is transferred to a developing device 14 containing yellow toner.
3 to form yellow 1 to toner images. Note that a predetermined developing bias voltage from a high voltage source is applied to this developing device.

CP for system control is used to replenish developer] and toner
A toner replenishing means (not shown) is controlled based on a command signal from U (not shown), so that toner is replenished when necessary. '' The two series of yellow toner images are rotated with the cleaning blade 147a released, and an electrostatic latent image is formed based on the second color signal (for example, the magenta signal) in the same manner as in the case of the first color signal. be done.

Then, by using a developing device 144 containing magenta toner, this is developed to form a magenta toner image.

Needless to say, a predetermined developing bias voltage is applied to the developing device 144 from a high voltage power supply.

Similarly, an electrostatic latent image is formed based on the third color signal (cyan signal), and a developing device 145 containing cyan toner is provided.
A cyan toner image is formed. Further, an electrostatic latent image is formed based on the fourth color signal (black signal), and is developed in the same way as between the sections by a developing device 146 filled with black toner.

Therefore, multicolor l/toner images are formed on the image forming body 142 in a superimposed manner.

Although the formation of a four-color multicolor toner image has been described here, it goes without saying that a two-color or single-color toner image can be formed.

As described above, the development process is a so-called two-component non-contact process in which each toner is caused to fly toward the image forming body 142 while AC and DC bias voltages from a high-voltage power source are applied. An example of development is shown.

On the other hand, the recording paper P fed from the paper feeding device 148 via the feed roll 149 and the timing roll 150 is conveyed onto the surface of the image forming body 142 in a state in which the timing is synchronized with the rotation of the image forming body 142. Ru. Then, the multicolor toner image is transferred onto the recording paper P by the transfer pole 151 to which a high voltage is applied from the high voltage power supply, and the separation pole 15
separated by 2.

The three separated recording sheets P are conveyed to the fixing device 153, where they undergo a fixing process and a color image is obtained.

The one-image formed body 142 after the transfer is transferred to the cleaning device 14
7 to prepare for the next image forming process.

In the cleaning device 147, a predetermined DC voltage is applied to the metal roll 147b in order to facilitate recovery of the toner cleaned by the cleaning blade 147a. This metal roll 147b is placed on the surface of the image forming body 142 in a non-contact state. cleaning blade 1
47a is released from pressure bonding after cleaning is completed, but in order to release unnecessary toner that is left behind at the time of release, an auxiliary roller 147C is further provided, and this auxiliary roller 147c is rotated in the opposite direction to the image forming body 142 and is pressed against the image forming member 142. As a result, unnecessary toner is sufficiently cleaned and removed.

In the above description, the color image processing apparatus of this embodiment is applied to a digital copying machine, but the present invention is not limited to this. That is, it goes without saying that the present invention can be applied to various devices that process character images and gradation.

In addition, in this embodiment, since the case where image reading is performed in R, G, and B is shown, both images 'I'll also be read in R, G, and B.
, B, but is not limited to this.

In other words, when performing dual image reading using other colors,
It suffices to perform image-by-image I'll and majority decision processing in accordance with the color of the reading.

(Effects of the Invention) As explained in detail above, in the present invention, a universal image in which a character image (achromatic color character image, chromatic color character image) and a gradation side are mixed is generated for each primary color image signal. The image is discriminated, and different color reproduction processes are executed for the character image and the gradation side based on the majority of the discrimination results. That is, when it is determined that the image is a character image, the color reproduction process emphasizes the background and character colors, and when it is determined that the image is on the gradation side, the color reproduction process emphasizes the intermediate gradation. Therefore, even if the I'll results vary for each color, erroneous classification and inappropriate color reproduction processing will not occur due to majority voting processing.For this reason, high-quality image processing suitable for each type of image can be performed. It is possible to realize a color image processing device that can perform the following operations.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing the electrical configuration of an embodiment of the present invention;
Fig. 2 is a block diagram showing the configuration of the discrimination circuit, Fig. 3 is an explanatory diagram for explaining the operation of the low-pass filter, Fig. 4 is a block diagram showing the structure of the low-pass filter, and Figs. 5 and 6 are An explanatory diagram explaining the characteristics of the low-pass filter, FIG. 7 is a configuration diagram showing the electrical configuration of the low-pass filter, FIG. 8 is a configuration diagram showing the configuration of the level determination circuit, and FIG. 9 explains the characteristics of the level determination circuit. 10 is a configuration diagram showing the electrical configuration of the level determination circuit, FIG. 11 is an explanatory diagram of the filter effect, FIG. 12 is an explanatory diagram explaining the result of image discrimination, and FIG. A configuration diagram showing the configuration of the determining means, 1st
Figures 4 and 15 are explanatory diagrams of the operation of the second discrimination means, ↑6
The figure is a configuration diagram showing the mechanical configuration of a copying machine to which the color double image processing device of this embodiment is applied. 1... Original 2.3... Dichroic mirror 456, CCD 789... A/D converter 10 11.12... Shading compensation j [Circuit 13.
14.15... Gate 16... Density conversion circuit 17... Color reproduction section 18
...One selector...Multi-value processing unit 20.
・Printer unit 2], 22.23...Discrimination circuit 24...Majority circuit

Claims (1)

[Claims] A color reproduction table for converting primary color image signals obtained by scanning a document into color signals for image recording is provided for both character images and gradation images. a color reproduction means for performing color reproduction using one of the color reproduction tables based on a judgment signal received; a mixed image discrimination means for discriminating a document image into a gradation image and a character image for each primary color image signal; 1. A color image processing device comprising: majority decision means for supplying a majority of the results of discrimination for each primary color image signal by the image discrimination means to the color reproduction means as a decision signal.