JP3262553B2 - Color image processing apparatus and color image processing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a color image processing apparatus and a color image processing method.

[0002]

2. Description of the Related Art Conventionally, as disclosed in Japanese Patent Publication No. 56-48869, in a color printing apparatus, the levels of a plurality of primary color signals are compared. There is known a technique for preventing deterioration of image quality due to misregistration of a plurality of primary colors by coloring on the top.

Further, for example, in a color copying machine, there is a technique for automatically determining whether a read original is a black-and-white original or a color original, executing black monochrome printing for a black-and-white original, and performing color printing for a color original. Are known. By determining the type of the original, the copy execution time can be reduced,
Expenses can be reduced.

[0004]

However, according to the above-mentioned prior art, pixels around the black characters of the input image are erroneously determined to be chromatic due to a shift in the reading position of the color sensor for image input. There were many. For this reason, it has not been possible to suppress color fringing occurring around the black characters of the output image.

In particular, a three-line sensor as shown in FIG.
(Red), G (Green), and B (Blue) line sensors are arranged in parallel at a certain distance, but the reading of each line sensor is caused by vibration of the optical system driving motor and the like. The positions are slightly different. That is, a three-line sensor generally detects different lines on a document as R, G, and B.
The line sensor of each color reads and performs appropriate processing to obtain pixel information of the R, G, and B color component signals related to the same line on the document. Even if the signal processing is performed, the deviation of the reading position between lines cannot be ignored.

In addition, there is a problem that a black-and-white document and a color document are erroneously determined in accordance with the chromatic / achromatic erroneous determination.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a color image processing apparatus and a color image processing method capable of generating a black single-color signal for a black area of an image with a simple configuration and with high accuracy.

[0008]

In order to solve the above-mentioned problems, a color image processing apparatus of the present invention inputs three primary color signals of R (red), G (green), and B (blue) according to an image. Input means for performing the operation, and black area determination means for determining a black area of the image based on the three primary color signals;
First generation of generating a Bk (black) single color signal using a G (green) signal without using an R (red) and B (blue) signal other than a G (green) signal among the three primary color signals And Y ( yellow ), M (magenta), C (cyan), Bk based on the three primary color signals.
A second generation means for generating a (black) signal; and a Bk (black) monochrome signal generated by the first generation means for an area determined to be a black area by the black area determination means. Then, Y ( yellow ), M (magenta), and Y ( yellow ) generated by the second generation unit for an area determined to be not a black area by the black area determination unit.
An output means for outputting C (cyan) and Bk (black) signals. Further, the image processing method of the present invention uses R (red), G (green), B
An input step of inputting three primary color signals (blue);
A black area determining step of determining a black area of the image based on the three primary color signals; and R (red) and B (blue) of the three primary color signals other than a G (green) signal.
A first generation step of generating a Bk (black) single color signal using a G (green) signal without using a signal;
The second generation step of generating Y ( yellow ), M (magenta), C (cyan), and Bk (black) signals based on the primary color signal, and the black area determination step determine that the area is a black area. A Bk (black) single-color signal generated in the first generation step is output to the area, and the area generated by the second generation step is determined to be not a black area in the black area determination step. Y ( Ye
( Low ), M (magenta), C (cyan), and Bk (black) signals.

[0009]

[0010]

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 First, the configuration of a three-line sensor according to a first embodiment of the present invention will be described.

FIG. 1 is a block diagram of a sensor unit of the image processing apparatus according to the present embodiment. In the figure, 1-1 is an R (red) color sensor, 1-2 is a G (green) color sensor, 1-3 is a B (blue) color sensor, 1-4, 1
-5 and 1-6 are analog / digital converters, 1-7 is R
A sensor signal delay memory, 1-8 is a G sensor signal delay memory, 1-9 is an R sensor signal interpolator, and 1-10 is a G sensor signal interpolator. Reference numeral 1-11 denotes a clock generator which drives the sensors 1-1, 1-2, and 1-3 using the same clock. The clock generator generates a pixel clock (generates a CCD transfer clock) in synchronization with a horizontal synchronizing signal sent from the printer or the microprocessor 2-11 in FIG.

FIG. 2 is a block diagram of the delay memories 1-7 and 1-8 and the interpolators 1-9 and 1-10 of FIG.

2-1 is an R signal delay memory constituted by a FIFO memory, and 2-2 is a G signal constituted by a FIFO memory.
A signal delay memory, 2-3 and 2-4 are selectors for selecting which part of the FIFO memory to send sensor line data to the multiplier, and 2-5, 2-6, 2-7 and 2-8 are multipliers , 2-9 and 2-10 are adders. Reference numeral 2-14 denotes an operation unit for inputting and displaying a magnification and the like, and 2-11 denotes a microprocessor. Multipliers 2-5, 2-6, 2-7, 2 based on magnification data from the operation unit 2-14. -8 and the selectors 2-3 and 2-4.

FIG. 3 is a configuration diagram of a three-line parallel color sensor. Reference numeral 301 denotes an R (red) line sensor, 302 denotes a G (green) line sensor, 303 denotes a B (blue) line sensor, and 304 denotes a color sensor IC body.

In the present embodiment, the interval between the line sensors is 180 μm, the sensor pixel width is 10 μm, and the delay memory sizes of FIGS. The signal delay memory is a 36-line memory, and the G signal delay memory for the G signal 2-2 is an 18-line memory.

In this embodiment, in order to enable zooming in the sub-scanning direction from 100% to 400%, R in FIGS.
The signal delay memory size is composed of 144 line memories, and the G signal delay memory size is composed of 72 line memories.

FIG. 4 is a block diagram of the reading apparatus.

Reference numeral 401 denotes a color sensor IC body; 402, an R line sensor; 403, a G line sensor;
Line sensor, 405 is the third reflection mirror, 406 is the second reflection mirror
A reflection mirror, 407 is a first reflection mirror, 408 is an original plate glass, 409 is an original platen, 411 is an illumination lamp for exposing the original, 412 is an image forming lens, and 410 is a reading device main body. The original is scanned in the direction of the arrow in the figure.

Here, FIG. 6 shows a schematic diagram of the reading device.

Reference numeral 601 denotes an original; 602, a lamp for illuminating the original 601; 603, a mirror; 604, a lens for forming an image of light from the original reflected by the mirror 603 on a three-line sensor 605 as a light receiving element; Department.

FIG. 5 shows the microprocessor 2-11 of FIG.
It is a processing flowchart of.

Hereinafter, description will be made with reference to the processing flow chart of FIG.

The scaling factors N and m are obtained by dividing the distance between the R sensor and the B sensor by the distance between the sensors in the sub-scanning direction or the reading pixel pitch in the sub-scanning direction at the same magnification.

Now, let us consider the case of changing the magnification in the sub-scanning direction by 105%, where N = 1.05. As described above, since m = 36 in the present embodiment, the number of pixels included in the interval between the R line sensor and the B line sensor is N × m = 1.05.
× 36 = 37.8 (pixels). Here, N × m is the number of read pixels between sensors at the magnification N.

In the FIFO memory shown in FIGS.
The pixel data of the 37th line is set to D (37), and the pixel data of the +38 line is set to D (38), and R corresponding to the same position as the document position currently read by the B (blue) sensor by the linear operation of Expression (1). (Red) Find the value of the signal.

D (37.8) = 0.2 × D (37) + 0.8 × D (38) Equation (1)

The microprocessor 2-11 performs control corresponding to the above-mentioned interpolation processing.

At step 500, N and m are set, and at step 501, the microprocessor 2-11 performs the operation of equation (2).

A = N × m− [N × m] Equation (2) Here, [] is an integer conversion process in which a decimal part is truncated.

In the case of this embodiment, since m = 36, 10
In the case of 5% magnification change in the sub-scanning direction, A = 36 × 1.05- [36 × 1.05] = 0.8 (3)

At 502, the microprocessor 2-11
The coefficient A is set as a multiplication coefficient in the multiplier 2-5.

In step 503, the value of [N × m] is obtained, and the selector 2-3 is set. The value of [N × m] is an integer part of the pixel interval in the sub-scanning direction of the R line sensor and the B line sensor during zooming. When m = 36 and N = 1.05 [N ×
m] = 37, and D (37) of the FIFO memory 2-1
(: Pixel data of +37 line) is a multiplier 2-
6 so that the data of D (37 + 1) of the FIFO memory 2-1 flows to the multiplier 2-5.
Reference numeral -11 sets the selector 2-3.

In step 504, the value of (1-A) is obtained,
-6 is set as the multiplication coefficient. In this way, the calculation of equation (1) is performed, and the data of R is obtained.

Next, in order to obtain the data of G, the operation of equation (4) is performed.

E = N × 1− [N × 1] (1) where 1 is the distance between the G sensor and the B sensor divided by the distance in the sub-scanning direction of the sensor or the read pixel pitch at the same magnification. Number.

In this embodiment, since l = 18, 1
In the case of changing the magnification in the sub-scanning direction by 05%, since N = 1.05 and N × l = 18.9, D (18.9) = 0.1 × D (18) +0.9 × D (19) Expression (5) needs to be obtained. Therefore, E = 18 × 1.05- [18 × 1.05] = 0.9 Expression (6) is set, and the value of [N × 1] is obtained in 506, and the selector 2
-4 is set. The value of [N × 1] is an integer part of the pixel interval in the sub-scanning direction between the G line sensor and the B line sensor during zooming. l = 18, N = 1.05 [N ×
l] = 18, and D (18) of the FIFO memory 2-2
(+18 line pixel data) is added to the adder 2-8.
The microprocessor 2-11 sets the selector 2-4 so that the data of the D (18 + 1) line of the FIFO memory 2-2 flows to the multiplier 2-7.

In step 507, the value of E = 0.9 is set in the multiplier 2-7 as a multiplication coefficient. (1-E) = 0.1 at 508
Is set as a multiplication coefficient in the multiplier 2-8. In this way, the operation of the equation (4) is performed, and the data D of G (18.9)
Is required.

In the above example, m and l are integers. However, it is actually difficult to accurately create distances between the R sensor and the B sensor and between the G sensor and the B sensor. For example, when the distance in the sub-scanning direction of the sensor (or the read pixel interval in the sub-scanning direction at the same magnification) is 10 μm, the distance between the R sensor and the B sensor is 365 μm, and the distance between the G sensor and the B sensor is 178 μm.
When it becomes m, m becomes 36.5 and 1 becomes 17.8. In this case, interpolation processing is also required at the same magnification, that is, when N = 1.0, and the equations (1) and (4) are as follows.

A ′ = 1 × 36.5− [1 × 36.5] = 0.5 ΔD (36.5) = 0.5 × D (36) + 0.5 × D (37) Equation ( 1) ′ E ′ = 1 × 17.8− [1 × 17.8] = 0.8 ∴D (17.8) = 0.2 × D (17) + 0.8 × D (18) Equation ( 2) 'In any case, it can be realized by the flowchart of FIG.

Next, the configuration and operation of a reading apparatus using the above three-line sensor will be described with reference to FIGS.

7 and 8, reference numeral 701 denotes a machine box;
Reference numeral 2 denotes an original placing glass, reference numeral 703 denotes an original, and reference numeral 409 denotes an original pressing plate for pressing the original. Reference numeral 407 denotes a first mirror, which is a support member 707 slidable along rails 706 and 706 '.
707 '. Reference numeral 411 denotes a lamp for illuminating the document 3, and 709 denotes a lamp cover. The lamp 411 and the lamp cover 709 are fixed to a support member, and move together to form the first mirror unit A. 406 and 405 are second and third mirrors, and support members 713 and 71 slidable on the rails 706 and 706 '.
3 'is supported. Also, the support members 713, 71
Reference numeral 3 'is held by a second mirror cover 714, which moves together to form a second mirror unit B. The first and second mirror units A and B move synchronously in the same direction at a speed ratio of 2: 1.

Reference numeral 412 denotes an imaging lens and 401 solid-state image sensor.

Reference numeral 717 is a motor, 718 is a timing belt, and 719 is a drive shaft. A drive pulley 720, large pulleys 721, 721 ', and small pulleys 722, 722' having a half diameter of the large pulley are fixed to the drive shaft 719, and these rotate synchronously. 723, 723 ', 7
24,724 'is the tension pulley, the rotation axis 725 _A of the tension pulley, 725 _A', 725 _B, 725
'The spring _{726 A, 726 A' B,} 726 B, 726
_B 'is attached.

Numerals 727 and 727 'are long wires, both ends of which are attached to the first mirror supporting members 707 and 707', and are wound around the large pulleys 721 and 721 'several times and wound around the tension pulleys 723 and 723'. Have been. The long wire 727,727 ', the spring 726 _A, 7
26 _A 'tension 3~4kg has been added, the large pulley 721,721' This rotational force when the rotation is supported via a long wire 727,727 'member 707,70
7 ', the first mirror unit A slides.

Short wires 728 and 728 'are attached to the second and third mirror support members 713 and 713' at both ends, and are rotated several times on the small pulleys 722 and 722 ', and are connected to the tension pulleys 724 and 724'. It is wound half a turn. The spring 726 _B in the short wire 728,728 ',
726 _B 'applies 3-4 kg tension,
When the small pulleys 722, 722 'rotate, the second mirror unit B slides.

The original 703 is placed on the original placing glass 7
2 and press a read key (not shown) to turn on the lamp 411, and the first and second mirror units A and B located at the home positions indicated by solid lines in FIG. To start the forward movement. As a result, the original surface of the original 703 is scanned in succession along the longitudinal direction of the lamp 411, and the light reflected from the original surface is reflected by the first, second, and third mirrors 407, 406, 405 and Slit exposure is performed on the solid-state imaging device 401 via the image lens 412, and reading is performed. In the above reading operation, the first mirror unit A and the second mirror unit B move synchronously at a speed ratio of 2 to 1, so that the distance (optical path length) from the document surface to the solid-state imaging device 401 is kept constant. ,
The original image is slit-exposed without blur.

When the first and second mirror units A and B reach the reversal positions indicated by broken lines in FIG.
When the backward movement is started and the first mirror unit A moves to the document reading start position C, the brake is applied, and
The second mirror units A and B stop at the home position indicated by the solid line in FIG. In the case of repeated reading, the above operation is repeated a set number of times.

In FIG. 4, if the moving speed of the mirror 407 is v, the distance between the line sensors is 1, and the time required for reading one line of data is t, the required number L of delay lines is expressed by the following equation.

L = 1 / v × 1 / t (1)

Although it is assumed that the transfer speed v in the equation (1) is constant, the performance of the motor driving the mirror 407 (for example, causing a cogging phenomenon) and the movement speed due to the drive mechanism are reduced. A shift Δv occurs. The shift amount Δv of the moving speed is an amount that changes with time and takes a positive or negative value.

Since the number of delay lines L shown in one method (1) is fixed, a shift occurs in the reading position on the document for each line sensor, thereby causing a color shift.

The color shift caused by this phenomenon is different from a simple color shift (for example, reddish) and differs depending on the reading position because the shift amount Δv of the mirror moving speed changes with time. Complicated color shift occurs.

Therefore, when reading an achromatic image document represented by only a black character using the parallel color sensor 401, complicated color misregistration occurs, and the monochrome / color determination of the document to be read is performed. This was also a major cause of misjudgment.

In this embodiment, this is solved by the following means.

In the block diagram of the black area determination circuit shown in FIG. 9, reference numerals 101, 102, and 103 denote input color signals.
R (red), G (green), B (blue) respectively
Is an 8-bit digital signal corresponding to. These signals are input by the image sensor as described above. 10
4, 105, and 106 are smoothing circuits for the R, G, and B color signals, respectively, and 107 is the maximum value A (A = A) of the R, G, and B signals.
max (R, G, B)), and 108 is a circuit for detecting R,
This circuit detects the minimum value B (B = min (R, G, B)) of the G and B signals.

Reference numeral 109 denotes D = max (R, R, D) based on the values obtained by the maximum value detection circuit 107 and the minimum value detection circuit 108.
G, B) -min (R, G, B) circuit 110
Is a circuit that compares the value D calculated by 109 with the constant a, and outputs a comparison result represented by Expression (1).

D <a: output 1 D ≧ a: output 0 (1) 111 compares A (A = max (R, G, B)) with a constant b and compares the result with the expression (2) Is a circuit that outputs.

A <b: output 1 A ≧ b: output 0 (2) 112 is a circuit that performs an AND operation on the output signals from 110 and 111, and 113 is a circuit that corrects the black area signal output from 112 .

In this embodiment, the higher the lightness, the larger the input color signal value. Therefore, D = ma
x (R, G, B) -min (R, G, B) is a constant a
1 and the value of A = max (R, G, B) is smaller than the constant brightness corresponding to the constant b, that is, FIG.
If the input color signal value is included in the shaded area indicated by 2, the AND circuit 112 outputs 1 to the black area signal correction circuit 113. In other cases, that is, when the input signal value is not included in the hatched area shown in FIG.
Is output to the correction circuit 113.

By appropriately setting the constants a and b, the black area of the input image can be identified from the other chromatic areas and the bright original background.

However, as described above, there is a possibility that an erroneous determination may occur in a portion around the black region due to the effect of the color misregistration error of the input color signal. Black area signal correction circuit 113
Corrects the erroneous determination. Note that 114
Indicates the black character of the document, and the determined black area signal, 1
Reference numeral 16 denotes a determination signal after passing through the correction circuit 113, and reference numeral 115 denotes a line buffer.

FIG. 10 is a functional block diagram of the black area signal correction circuit 113. In FIG. 10, reference numeral 116 denotes a line buffer for storing the black area signal 114 output from the AND circuit 112, which is constituted by one bit per pixel. An OR circuit 113 corrects the black area signal 114 stored in the line buffer 115 and outputs a determination signal 116. This circuit includes a correction target pixel e and 8
OR the values of the pixels (a, b, c, d, f, g, h, i), and if at least one of a to i is 1, 1
Is output when all of a to i are 0. FIG.
FIG. 5 shows an example of correction by this correction circuit. Correction Example 1 is a-
Of the pixels of i, a, b, d, e, g, h are 0 and c, f,
In this case, i is 1, and in this case, the value of e after correction is 1 even if the value of the correction target pixel e before correction is 0. In correction example 2, only b is 1 and all the other pixels are 0. In this case as well, even if the value of the correction target pixel e before correction is 0, the value of e after correction is 1 .

FIG. 14 is a diagram for explaining the process from the original black character to the reproduction of the corrected black area based on the present embodiment.
Reference numeral 1 denotes an original black character, 602 denotes an input image, 604 denotes a black area before correction, and 605 denotes a black area after correction. As shown in FIG. 14, the original black character 601 is read, and the determined black area signal 114 is determined to be narrower than the original black character 604 as indicated by 604 due to the color shift error 603 of the input color signal generated when reading around the original black character. . Therefore, the correction circuit 113 corrects the black area signal 114 and outputs a determination signal 116.
Is output, the thickened corrected black area 60
5 is reproduced.

FIG. 11 shows the smoothing circuits 104-1 in FIG.
It is a block diagram which shows the function of 06. In FIG.
A line buffer 301 stores an input color signal, and is composed of 8 bits per pixel. Reference numeral 302 denotes a smoothing operation unit that outputs an input color signal stored in the line buffer 301 as a smoothed color signal. The arithmetic unit calculates four pixels (j,
The smoothed color signal is output by taking the weighted average represented by n = (4n + j + k + 1 + m) / 8 using (k, l, m).

FIGS. 13 (a), 13 (b) and 13
FIG. 9C is a diagram showing the result of a computer experiment. Fig. 13-
FIG. 13C is a diagram showing an example of a black character original, and FIG.
(A) and FIG. 13- (b) show max for the color signal.
The distribution of (R, G, B) -min (R, G, B) is shown. FIG. 13A shows an input color original signal before the smoothing process is performed, and FIG. 13B shows a smoothed color signal after the smoothing process is performed. As is apparent from FIG. 2, when the smoothing process is performed, the input max
It is experimentally that the variation of (R, G, B) -min (R, G, B) is reduced, and it is effective to use a smoothed color signal for the determination process for extracting a black region. Was confirmed. In particular, a remarkable effect is seen in a character having a large number of strokes as shown in FIG.

FIG. 16 is a block diagram of the color signal processing based on the black area determination signal.

In FIG. 16, reference numeral 800 denotes an image reading unit;
01 is a logarithmic converter, 802 is a masking converter, 803
Is a UCR (under color removal) unit, and 804 is a selector.

An R signal, a G signal, and a B signal input from an image reading unit (for example, a CCD) 800 undergo logarithmic conversion at 801, undergo masking calculation at 802, and output Y, M, and C signals.
The signal is subjected to under color removal processing (UCR) at 803 and input to the selector 804 as a Y 'signal, M' signal, and C 'signal.

On the other hand, the R signal, the G signal, and the B signal are sent to a black area determination unit 806 via a smoothing circuit. Here the first
The black area determination shown in the figure is performed. Black area determination unit 806
If the pixel is determined to be a black area, the selector 804 outputs y (yellow), m (magenta), c
(Cyan), Y ", M", bk (black)
C ", Bk" are selected.

Here, Y ″, M ″, and C ″ are outputs from the 0 data generator 805, and their values are 0. Therefore, the values of the outputs y, m, and c of the selector are all 0. Bk ″ is an LUT (look-up table) 808 after logarithmic conversion of a G (green) signal among input color signals.
Is the density corrected.

As shown in FIG. 16 , a signal input to the determination unit 806 uses a smoothed signal, and a signal for printing is sent to the printer 809 without being separately smoothed. As a result, the output signal does not deteriorate due to the signal processing for the determination.

Of the three primary color signals of R (red), G (green) and B (blue), the G (green) signal is used for each of the R, G and B sensors in FIG. This is because the G signal is closest to the neutral density image (ND image) as shown in FIG. That is,
In a method of generating a neutral density signal by calculating using each signal of R, G, B (for example, NTSC Y signal), R, G, B
There is a case where the sharpness of the image is reduced due to the influence of the displacement of each signal of B. On the other hand, if a monochromatic G signal is used for the output of the black area, the circuit configuration is simplified and the MTF
There is an advantage that deterioration of the can be prevented.

On the other hand, if it is determined that the area is not a black area, the selector 804 determines whether Y ′, M ′, C ′, B
k ', and outputs Y', m, c, bk as Y ',
M ′, C ′, and Bk ′ are sent to the printer 809.

In this embodiment, when the three primary color filters of R, G, and B are used in the image reading unit 800, a monochromatic G signal is used to output a black region.
The same can be said for the present embodiment when other filters such as three colors of C (cyan), Y (yellow), and W (white) are used. That is, in this case, Y,
By outputting an achromatic region from a single color of a W (white) signal without performing an operation using each of the M and C signals, the circuit configuration is simplified and MTF deterioration can be prevented. The same effect as described above can be obtained.

As an improvement of the above-mentioned CCD three-line sensor, the one shown in FIG.

In FIG. 17, reference numeral 1701 denotes a red component (R) line sensor, which is a filter that transmits only red component light and covers the surfaces of a plurality of light receiving elements of the line sensor. Similarly, reference numeral 1702 denotes a green component (G) line sensor, and reference numeral 1703 denotes a blue component (B) line sensor. A plurality of light receiving element surfaces are covered with filters that transmit only green component and blue component light, respectively. .

Each line sensor is arranged adjacently and in parallel at a pitch of 180 μm, and the B line sensor is constituted by a light receiving element array of 20 μm × 10 μm.
The R and G sensors are constituted by a 10 μm × 10 μm light receiving element array. Here, the light receiving areas of the light receiving elements of B, R and G are different for the following reason. That is, in general,
The transmittance of blue light in a filter transmitting only blue component light tends to be lower than the transmittance of red / green light in a filter transmitting only red / green component light. Therefore, in order to improve the S / N ratio (signal-to-noise ratio) of the signal, the light receiving area of only B is increased, and the levels of the R and G signals are matched. Therefore, FIG.
As shown in 7- (b), the input level of the B sensor, R,
The input level of the G sensor is not uniform, and a color shift occurs.

In the reduction optical system, the amount of color misregistration due to vibrations on the original surface is amplified and transmitted to the sensor, and the effect of color misregistration due to uneven speed during movement in the sub-scanning direction is more strongly affected. The achromatic region determination unit and the output signal correction unit described in the embodiment become effective.

Second Embodiment In the first embodiment, a process of outputting a single black color when a black area is determined is performed. However, when a color halftone image is an input document, the black portion of the document is emphasized. In some cases, black in color dots of an output image is unnaturally emphasized.

In the present embodiment, when a chromatic pixel is in the vicinity of an achromatic pixel, the above-mentioned disadvantage is eliminated by not setting this as a black area.

FIGS. 18, 19, and 20 are views for explaining a second embodiment of the color image processing apparatus of the present invention. FIG. 18 is a block diagram of a black area determination circuit of the processing apparatus, and FIG. FIG. 20 is a block diagram of a chromatic pixel number counting circuit of the processing device, and FIG.
FIG. 3 is a diagram illustrating a chromatic region in a (G, B) space.

In FIG. 18, reference numerals 101 to 115 are the same as those in FIG. 901 is D = max (R,
G, B) -min (R, G, B) is a comparison circuit for comparing whether or not the value is larger than a constant C, and determines whether or not the pixel is included in a hatched portion in FIG.

In the case of a chromatic pixel, D = max (R, G, B)
Since the value of −min (R, G, B) is larger than the achromatic pixel, it is possible to determine whether the pixel is chromatic or achromatic by appropriately setting the constant C. This comparison circuit 9
01 outputs 0 when D ≦ C, and outputs 1 when D> C.

Reference numeral 902 denotes a 3-line FIFO buffer memory for storing the result of chromatic pixel determination. 903
Is a counter for counting the number of chromatic pixels present in the eight pixels near the pixel. That is, as shown in FIG. 19, considering the pixel S stored in the line buffer 902, this pixel S and neighboring pixels o, p, q, r, t,
The number of pixels determined as chromatic pixels among u, v, w is E
And is output from the counter 903.

A comparison circuit 904 determines whether or not the number E of chromatic pixels measured by the counter 903 exceeds a constant d (d = 1 in this embodiment). That is, the comparison circuit 904 outputs 0 when E> d, and outputs 1 when E ≦ d.

According to the above-described processing, a black area is determined only when the number of chromatic pixels is equal to or less than a specific number (corresponding to a constant d) in the vicinity of eight connected pixels.

Reference numeral 905 denotes an AND circuit, and the correction circuit 11
When both the output of 3 and the output of the comparison circuit 904 are 1, 1 is output as the determination signal 906, and otherwise, 0 is output.

Thus, when the input color document is a color halftone image, it is possible to prevent black in the color halftone dots from being unnaturally emphasized.

In this embodiment, the chromatic color area determination is also performed by using the same number of neighboring eight pixels as the achromatic color area determination.
The number of neighboring pixels may be different between the chromatic color area determination and the achromatic color area determination.

Embodiment 3 FIG. 21 is a view for explaining a third embodiment of the color image processing apparatus according to the present invention, and is a block diagram of a black area determination circuit.

In the second embodiment, when a chromatic pixel is present in the vicinity of the pixel, the black area determination is prevented. In the present embodiment, the black area in the vicinity of the pixel is prevented. By comparing the number of judgment pixels f with the number of chromatic judgment pixels E,
When f> E, a black area determination is performed.

In FIG. 21, reference numeral 1201 denotes a 3-line FIFO buffer memory for storing the result of the black area determination, and reference numeral 1202 denotes a counter for counting the number of black pixels of eight pixels near the pixel. Reference numeral 1203 denotes a circuit (comparator) for comparing the number f of black pixels with the number E of chromatic pixels, where f> E
1 is output as the determination signal 1204 when f ≦ E, and 0 when f ≦ E.

According to the present embodiment, when a chromatic pixel exists in the vicinity of a black pixel, an unnatural black is prevented from being generated in an output image of a color halftone dot original by preventing a black area determination. be able to.

As described above, according to the first to third embodiments of the present application, by providing the means for correcting the determined black area signal, the black area caused by the displacement of the input color sensor or the like is provided. Color fringing around black characters due to erroneous determination can be prevented.

Further, by determining the black area by smoothing the input color signal, more accurate black area determination can be performed.

Further, by processing the input color signal using a specific single color component of the input color signal, the circuit configuration is simplified.

Embodiment 4 FIGS. 23 to 30 are views for explaining a fourth embodiment.

In the block diagram of the judgment circuit shown in FIG.
2101 is a CCD with R (red), G (green), B
(Blue), for example, the three-line sensor of the first embodiment can be used. 2102
Is an A / D converter that outputs a digital signal of 8 bits (256 gradations) with respect to the analog input signal.
A line buffer for storing G and B digital color signals, an address sequencer 2104 for controlling to read out R, G and B image data from the line buffer 2103 in order, and 2105 for each of R, G and B A circuit for detecting the maximum value of the 8-bit signal, 2106 includes R, R from the address sequencer 2104,
A circuit for detecting the minimum value of an 8-bit signal for each of G and B, 21
07 is a ROM (Read Only Memory) 16
Look-up table (L
UT) and (ma) in the hatched chromatic area shown in FIG.
It is configured to output 1 when x (R, G, B) and min (R, G, B)) are included, and to output 0 in other cases. Reference numeral 2108 denotes a counter (I) for counting the number of chromatic pixels of the target pixel and its surrounding eight pixels, 2
109 is the number of chromatic pixels measured at 2108 (A)
Is compared with a certain positive constant α, and outputs 1 when A> α, and outputs 0 otherwise. Reference numeral 2110 denotes a counter (II) for counting the number at which the output of 2109 becomes 1, and reference numeral 2111 denotes a microprocessor. 2112
A CCD drive circuit 2113 is a signal for controlling a color copy operation or a monochrome copy operation.

In the above configuration, each component performs the following operation.

The R (red), G (green), and B (blue) analog input signals read by the CCD 2101 are converted into 8-bit digital signals by the A / D converter 2102 and stored in the line buffer 2103. Is done. The line buffer 2103 can store image data for three lines, and a total of three line buffers are prepared for each of R, G, and B. Line buffer 210
FIG. 24 shows the state of the image data stored in No.3.

Next, a procedure for determining whether a certain pixel is a chromatic pixel or an achromatic pixel will be described. Now, assuming that a pixel e is a pixel to be judged in FIG. 24, first, 8-bit data for each of R, G, and B for the pixel e is stored in the line buffer 210 by the address sequencer 2104.
Access from 3 The maximum value detection circuit 2105 uses this data to generate a maximum value max of R, G, and B.
(R, G, B) is detected, and the minimum value detection circuit 2106 detects the minimum value min (R, G, B) of R, G, B. This max (R, G, B), min (R, G,
Each value of B) is an 8-bit digital signal and L
The data is input to a UT (lookup table) 2107.
The LUT 2107 is (max (R, G, B), min
If (R, G, B)) is included in the shaded area in FIG. 25, the pixel is determined to be a chromatic pixel, and the counter (I) 21
Outputs 1 to 08. On the other hand, if not included, it is determined that the pixel is an achromatic pixel, and 0 is output.

Here, FIG. 25 shows the relationship between (max (R, G,
FIG. 3B illustrates a chromatic color area in a B (), min (R, G, B)) space. Conventionally, as shown in FIG.
When the value A of ax (R, G, B) -min (R, G, B) exceeds a certain constant k, that is, when A> k,
A method for determining the pixel is known. In contrast,
As shown in FIG. 25, (max (R, G, B), min
(R, G, B)) The space can be divided into non-linear shapes and chromatic colors can be determined, so that the determination can be made more accurately.

The original image of black characters (achromatic color) is
(Max (R, G,
FIG. 27 shows the distribution of the (B), min (R, G, B)) space.

As described above, the chromatic / achromatic determination of the pixel e can be performed for the time being. However, with the above-described configuration only, there is a possibility that an erroneous determination may occur due to, for example, a displacement of the CCD sensor. is there. Therefore, in the present invention, such an erroneous determination is prevented by the following configuration.

That is, in FIG.
With respect to the surrounding eight pixels a, b, c, d, f, g,
For h and i (3 × 3 matrix area centered on e), the same chromatic / achromatic determination is performed as described above. Then, the number of the LUTs whose output is 1 for a total of nine pixels a to i, that is, the number of chromatic pixels is determined by a counter (I).
2108, and the counted number A is compared with the comparison circuit 2
109 and compare it with some suitable positive constant α.
, The pixel e is finally determined to be a chromatic pixel, and A ≦
In the case of α, it is determined that the pixel is an achromatic pixel.

As described above, erroneous determination can be prevented by performing chromatic / achromatic determination based on image information of a total of 9 pixels in a 3 × 3 matrix.

The comparison circuit 2109 outputs 1 when it is determined that the pixel is a chromatic pixel, and outputs 0 when it is determined that it is an achromatic pixel.

The series of operations up to this point is performed for all pixels on the original, and the number of times that the comparison circuit 2109 outputs 1 (ie, the number of chromatic pixels) is counted by the counter (II) 211.
When 0 is counted and the ratio J of the count number of the counter (II) to the total number of pixels is larger than a certain constant β, the microprocessor 2111 determines that the document is a color document, and otherwise determines that the document is a monochrome document. Perform each copy operation.

Microprocessor 2 in the above operation
The processing of step 111 will be described with reference to the flowcharts of FIGS. 28- (a) and 28- (b).

At S1, the microprocessor 211
1 controls the CCD drive circuit 2112 to start reading. The CCD drive circuit 2112 sends the conversion pulse to the A / D converter 2102, and converts the R, G, and B signals into 8-bit digital signals for each pixel.

First, the first line is scanned (S2) and Hs
Waiting for an interrupt of the sync (horizontal synchronization signal) (S3),
The process shifts to scanning of the next line (S4), and when scanning of the third line is completed (S5), image data necessary for determination is stored in the line buffer 2103.

At S 6, the 8-bit image data stored in the R, G, and B line buffers are sequentially accessed by the address sequencer 2104. Repeat for 9 pixels including the periphery of the determination target pixel (S
7) When the processing for one line is completed, the process returns to reading of the next line (S3) (S9). If all lines have been read, the counter value B of the counter (II) is read (S10), and the counter (I) for the total number of pixels is read.
The ratio of the count number of I) is set to J (S11). If the value of J is larger than an appropriate constant β, it is determined that the document is a color original (S12), and a color copy operation is performed (S13). On the other hand, if J ≦ β, it is determined that the document is a monochrome document (S12), a monochrome copy operation is performed (S14), and the color copy operation is omitted.

FIG. 29 is a diagram illustrating the configuration of the entire image processing apparatus.

In FIG. 29, reference numeral 2701 denotes an image reading unit;
Reference numeral 2702 denotes a color / monochrome determination unit, 2703 denotes an image processing unit, 2704 denotes an image reproduction unit, and 2705 denotes a control unit.

Based on the information of the image reading unit 2701, the color / monochrome determination unit 2702 determines whether the document is a color document or a monochrome document, and the image processing unit 2703 determines the color image if the document is a color document according to the determination of the determination unit 2702. Processing is performed, and black and white image processing is performed. In the case of a color original, the image reproducing unit 2704 is provided with Y (yellow), M (magenta), and C (cyan).
And color printing using inks such as Bk (black) for monochrome documents. By making such a determination, the copy time can be reduced,
Expenses can be reduced.

FIG. 30 shows an overall configuration diagram of a digital color copying machine to which the present invention is applied in this embodiment.

In FIG. 30, reference numeral 2201 denotes a portion for reading an original by an image scanner and performing digital signal processing. Reference numeral 2202 denotes a printer unit which prints out an image corresponding to the document image read by the image scanner unit 2201 on a sheet in full color.

In the image scanner unit 2201, 2
Reference numeral 200 denotes a mirror pressure plate. A document 2204 on a platen glass (hereinafter, platen) 2203 is irradiated with a lamp 2205, guided to mirrors 2206, 2207, and 2208.
D) An image is formed on 2210 and sent to the signal processing unit 2211 as full-color information red (R), green (G), and blue (B) components. Reference numerals 2205 and 2206 denote the speed v, and 2207 and 2208 denote the 1/2 v, and the entire surface of the document is scanned by mechanically moving in the direction perpendicular to the electrical scanning direction of the line sensor. The signal processing unit 2211 electrically processes the read signal, and outputs magenta (M), cyan (C), yellow (Y), and black (B
The component is decomposed into components k) and sent to the printer unit 2202. In addition, for one original scan in the image scanner unit 2201, one component among M, C, Y, and Bk is sent to the printer unit 2202, and one printout is completed by a total of four original scans.

The image signal of M, C, Y or Bk sent from the image scanner unit 2201 is sent to the laser driver 2212. The laser driver 2212 modulates and drives the semiconductor laser 2213 according to the image signal. The laser beam is a polygon mirror 2214, an f-θ lens 2215,
Scanning is performed on the photosensitive drum 2217 via the mirror 2216.

Reference numeral 2218 denotes a rotary developing unit, which comprises a magenta developing unit 2219, a cyan developing unit 2220, a yellow developing unit 2221, and a black developing unit 2222. The four developing units alternately contact the photosensitive drum 2217, The electrostatic latent image formed thereon is developed with toner.

Reference numeral 2223 denotes a transfer drum.
The paper fed from 224 or 2225 is wound around the transfer drum 2223, and the image developed on the photosensitive drum 2217 is transferred to the paper.

After the four colors of M, C, Y, and Bk are sequentially transferred in this manner, the sheet passes through the fixing unit 2226 and is discharged.

Embodiment 5 FIGS. 31 to 33 are views for explaining a fifth embodiment.

In the block diagram of the judgment circuit shown in FIG.
Reference numerals 2101, 2102, and 2105 to 2113 are the same as those in FIG. 2301 is a line buffer for storing a 1-bit signal from the LUT 2107;
Reference numeral 2 denotes an address sequencer for accessing data stored in the line buffer 2301 pixel by pixel via an address bus from the microprocessor 2111.

In the above configuration, each unit operates as follows.

R, G, B read by CCD 2101
Are converted into 8-bit digital signals by the A / D converter 2102, respectively. This R, G,
On the basis of the 8-bit signal of B, the maximum value detection circuit 2105 detects the maximum value max (R,
G, B), and the minimum value detection circuit 2106 detects
The minimum value min (R, G, B) of R, G, B is detected. This max (R, G, B), min (R, G,
Each value of B) is an 8-bit digital signal and L
The data is input to a UT (lookup table) 2107.
As in the case of the fourth embodiment, the LUT 2107 is (max
When (R, G, B), min (R, G, B)) is included in the shaded area in FIG. 25, the pixel is determined to be a chromatic pixel, and 1 is output. On the other hand, if it is not included, it is determined to be an achromatic pixel, and 0 is output.

The LUT 2107 determines chromaticity or achromaticity for each pixel scanned by the CCD 2101, and the result is stored in the line buffer 2301. The line buffer 2301 is capable of storing data for three lines, and proceeds to the following procedure when the data for three lines is completed.

FIG. 32 is a diagram showing the state of storage in the line buffer. Assuming that the final chromatic / achromatic pixel to be determined is e, the eight surrounding pixels a, b, c, d, f,
The address sequencer 2302 accesses the nine pixels including g, h, and i from the line buffer 2301 one pixel at a time, and the counter (I) 2108 counts one having stored data, that is, a chromatic pixel. Thereafter, the processing is the same as in the case of the fourth embodiment. The count number A is compared with an appropriate positive constant α in a comparison circuit 2109. If A> α, the pixel e is finally determined as a chromatic pixel. It is determined that the pixel is an achromatic pixel when A ≦ α. The comparison circuit 2109 outputs 1 when determining that the pixel is a chromatic pixel,
If the pixel is determined to be an achromatic pixel, 0 is output.

The series of operations up to this point is performed for all pixels on the original, and the number of times that the comparison circuit 2109 outputs 1 (ie, the number of chromatic pixels) is counted by the counter (II) 211.
When 0 is counted and the ratio J of the count number of the counter (II) to the total number of pixels is larger than a certain constant β, the microprocessor 2111 determines that the document is a color document, and otherwise determines that the document is a monochrome document. Perform each copy operation.

Microprocessor 2 in the above operation
The procedure of the process of 111 will be described with reference to the flowchart of FIG.

Steps S1 to S5 are the same as those in the fourth embodiment, and a description thereof will be omitted.

In S6, the address sequencer 230
2, the data stored in the line buffer 2301 is accessed. In this embodiment, since the chromatic / achromatic data for each pixel is already stored in the line buffer 2301, the target pixel and its 8 peripheral pixels, 9 total
It is sufficient to count the chromatic pixels in the pixels with the counter (I). Therefore, the processing speed can be increased as compared with the case of the fourth embodiment.

Steps S7 to S14 are the same as those in the fourth embodiment, and a description thereof will be omitted.

According to the present embodiment, by providing the line buffer 2301 after the LUT 2107,
The ax (R, G, B) and min (R, G, B) detection and the chromatic / achromatic determination can be omitted nine times per pixel, and the time required for processing can be reduced. Also,
There is no need to provide a line buffer for each of the R, G, and B colors after the A / D converter, and the device can be simplified.

Embodiment 6 FIGS. 34 to 36 show a sixth embodiment.

In the above-described fourth embodiment, the chromaticity determination of the pixel is performed based on the chromaticity determination signal of the pixel surrounding the chromaticity determination target pixel, and the monochrome / color determination of the input document is performed based on the determination signal. Was to do.

In the present embodiment, the chromaticity determination of the pixel is performed based on the chromaticity determination signal and the black determination signal of the peripheral pixel of the chromaticity determination target pixel, and the monochrome / color / color of the input document is determined based on the determination signal. The judgment is performed.

A color misregistration area of an input signal by a color sensor when an input document is black and white occurs near a black area as shown in FIG. Therefore, when there are some pixels that are determined to be black in the vicinity of the determination target pixel, erroneous determination due to color misregistration can be more reliably prevented by preventing chromatic determination.

FIG. 35 is a block diagram of a judgment circuit according to the sixth embodiment.

In FIG. 35, reference numerals 2101 to 2106, 2
Since steps 111 to 2113 are the same as those in FIG. 23, the description is omitted. 2401 is a 16-bit input for performing chromaticity determination,
A 1-bit output lookup table, 2402
Is a 16-bit input, 1-bit output lookup table for performing black determination. 2403 is the LUT (I)
When the output of 2401 is 1, that is, a counter (I) for counting the number of chromatic pixels C, 2404 is a LUT
(II) When the output of 2402 is 1, that is, a counter (II) for counting the number of black pixels Bk. 2405
Is the output C of the counter (I) 2403 and the counter (I)
I) A comparison circuit that compares the output Bk of 2404 and outputs 1 when C> Bk, that is, when the number of chromatic pixels is larger than the number of black pixels, and outputs 0 when C ≦ Bk. is there. Reference numeral 2406 denotes a counter (III) for counting the output of the comparison circuit 2405.

In the above configuration, each component performs the following operation.

The R (red), G (green), and B (blue) analog input signals read by the CCD 2101 are converted into 8-bit digital signals by an A / D converter 2102 and stored in a line buffer 2103. Is done. The line buffer 2103 can store image data for three lines, and a total of three line buffers are prepared for each of R, G, and B.

As in the case of the fourth embodiment, assuming that the pixel e is a pixel to be judged in FIG. 24, first, 8-bit data for each of R, G, and B for the pixel e is stored in the line buffer 2103 by the address sequencer 2104. Access from

Using this data, the maximum value detection circuit 210
5, the maximum value max (R, G,
B) is detected, and R,
The minimum value min (R, G, B) of G and B is detected. This max (R, G, B), min (R, G, B)
Are 8-bit digital signals, and the LUT
(I) 2401 and LUT (II) 2402 are input one by one.

FIG. 36 shows (max (R, G, B), min
It is a figure which shows the determination area | region in (R, G, B)) space.

Referring to FIG. 36, reference numeral 2501 denotes a white area;
2 is a black area, 2503 is an intermediate area, and 2504 is a chromatic area.

The LUT (I) 2401 is expressed as (max (R,
If (G, B), min (R, G, B)) are included in the chromatic area 2504 in FIG. 36, the pixel is determined to be a chromatic pixel, and 1 is output to the counter (I) 2403. On the other hand, when it is not included in the chromatic area 2504, 0 is output.

The LUT (II) 2402 is (max
When (R, G, B), min (R, G, B)) is included in the black region 2502 in FIG. 36, the pixel is determined to be a black pixel, and 1 is output to the counter (II) 2404. . On the other hand, when it is not included in the black area 2502, 0 is output.

The comparison circuit 2405 includes a counter (I) 24
The count number C of 03, ie, the number of chromatic pixels, is compared with the count number Bk of the counter (II) 2404, ie, the number of black pixels, and 1 is output when C> Bk, and 0 is output when C ≦ Bk. This output is counted by a counter (III) 2406, and a series of operations up to this point are performed on all pixels on the document, and the number of times the comparison circuit 2405 outputs 1
That is, the number of chromatic pixels is counted by the counter (III) 2406.
When the ratio J of the count number of the counter (III) to the total number of pixels is larger than a certain constant β, the microprocessor 2111 determines that the document is a color document, otherwise, determines that the document is a monochrome document, Each copy operation is performed.

Note that the flowchart of the processing of the microprocessor 2111 is almost the same as that of the fourth embodiment, and the description thereof will be omitted.

As described above, according to the present embodiment, the number of chromatic pixels and the number of black pixels are compared to determine whether the pixel to be determined is chromatic or achromatic. There is an effect that the determination accuracy is improved.

Embodiment 7 FIGS. 37 to 40 are views for explaining a seventh embodiment.

As shown in FIG. 34, the color bleeding of the input image of the black-and-white original remarkably occurs at the edge portion. In this embodiment, a means for detecting an edge portion is provided, and the edge portion does not perform color determination, thereby reducing erroneous determination.

Further, in this embodiment, the time required for copying can be reduced by making the scanning speed for reading the original black and white / color higher than at the time of image formation.

In the processing block diagram of the determination circuit of the seventh embodiment in FIG. 37, reference numerals 2101 to 2113 are the same as those in FIG. Reference numeral 2501 denotes an edge determination unit.
It is determined whether the pixel is an edge. Reference numeral 2503 denotes an AND circuit, which sends a chromaticity determination signal to the counter 2110 only when the pixel is not an edge portion.

In the above configuration, each unit operates as follows.

The basic operation is the same as that of the fourth embodiment, but in this embodiment, the original scan for black / white / color determination is performed at twice the speed of the read scan for the copy operation.

Therefore, as shown in FIG. 38, the size of the window to be subjected to the block processing is set to be twice as large in the main scanning direction as in the sub-scanning direction. The scanning direction is balanced.

The edge determining unit 2501 determines whether the pixel a to be determined is a pixel a as shown in FIG.
Is an edge portion. In FIG. 39, 2
Reference numeral 104 denotes an address sequencer, which sends 8 bits of G (green) data of pixels a to e to the arithmetic circuits 2504 to 2507 as shown in FIG. 2504-2507
Are arithmetic circuits, | ab |, | ae |, | a, respectively.
Output 8-bit data of −d |, | ac−. Here, as shown in FIG. 38, a is a pixel to be determined, b and e are pixels adjacent to the pixel a in the sub-scanning direction, and c and d are pixels a.
In the main scanning direction. The reason for taking such pixels is that in the present embodiment, the original scan for black / white / color determination is performed at twice the speed of a normal scan. Reference numeral 2508 denotes an addition circuit.
Sum F of outputs of 2504 to 2507 (F = | a−b | +
| Ae | + | ad | + | ac |). 25
A comparison circuit 09 determines that the edge is an edge and outputs 0 when the sum F is larger than a predetermined value γ, and outputs 1 when the total F is smaller than the predetermined value γ.

When both of the comparison circuits 2109 and 2509 are 1, the AND circuit 2503 operates the counter (II).
Output 1 to 2110; otherwise output 0.

In this way, for a pixel determined to be an edge portion, black / white / color determination is not performed, and erroneous determination can be prevented.

FIGS. 40- (a) and 40- (b) are flowcharts showing the processing of the microprocessor 2111 in the above operation. FIG. 40- (a), FIG.
In 0- (b), S1 to S10, S13, and S14 are the same as those in the fourth embodiment, and a description thereof will be omitted.

Steps S20 and S21 are steps for accessing the arithmetic circuits 2504 to 2507 from the line buffer 2103 with 8 bits of G (green) data of a total of five pixels a to e in FIG. .

In S22, if the value of the chromatic determination pixel number B is larger than the constant β, it is determined that the original is a color original. In particular, when the degree of color misregistration of the input color sensor is small, this determination method is effective. Thus, regardless of the size of the reading size, it can be determined that a color document exists if a color portion exists.

As described above, according to this embodiment, erroneous black / white / color determination can be prevented by not performing black / white / color determination of the edge portion.

Further, according to the present embodiment, the time required for the black / white / color determination can be reduced by making the original scan at the time of the black / white / color determination faster than the reading scan of the normal copy operation.

In the above embodiments, different LUTs (lookup tables) can be prepared depending on whether the output of the maximum value detection circuit or the minimum value detection circuit is R, G, or B. With this configuration, more appropriate table reference can be performed.

The processing after accessing data from the address sequencer may be performed by software under the control of a computer, instead of being performed by hardware.

Further, (max (R, G, B), min
When determining the chromatic color area in the (R, G, B)) space, it is also possible to approximate linearly instead of nonlinearly.

Note that the determination of chromatic / achromatic is not necessarily 3 × 3
It is not necessary to perform the processing with a total of 9 pixels of the matrix, for example, a total of 5 pixels including the upper, lower, left and right of the target pixel, or a 5 × 5 matrix of 25 pixels in total.

As described above, according to the color image processing apparatuses of the fourth to seventh embodiments of the present application, the specific pixel in the block area is obtained from the pixel information of the block area including a plurality of pixels. Means for generating a chromatic / achromatic determination signal, and having means for automatically determining whether the input image signal is a monochrome image signal or a color image signal based on a plurality of the determination signals, Erroneous determination in the above determination can be prevented.

Embodiment 8 FIG. 41- (a) is an overall configuration diagram of the eighth embodiment.
In FIG. 41A, reference numeral 3201 denotes a portion which reads an original by an image scanner and performs digital signal processing.

In the image scanner section 3201, 3
Reference numeral 200 denotes a mirror surface pressure plate, and a document 3204 on a platen glass (hereinafter referred to as a platen) 3203 is irradiated with a lamp 3205, guided to mirrors 3206, 3207, and 3208, and transmitted by a lens 3209 to the three-line sensor described in the first embodiment. An image is formed on a CCD (CCD) 3210 and sent to a color determination unit 3211 as full-color information red (R), green (G), and blue (B) components. 3205
Reference numeral 3206 denotes a speed v, and 3207 and 3208 scan the entire original by mechanically moving in a direction perpendicular to the electrical scanning direction of the line sensor at 1/2 v.

FIG. 41- (b) is an internal block diagram of the image scanner section. In FIG. 41- (b), 310
Reference numeral 1 denotes a counter which outputs a main scanning address 3102 for specifying a main scanning position of the CCD 3210. That is,
When the horizontal synchronization signal HSYNC is 1, C (not shown)
PU sets the pixel clock signal CL to a predetermined value.
Incremented by K.

The image formed on the CCD 3201 is 3
Are photoelectrically converted by the three line sensors 3301, 3302, and 3303, and read as R component, G component, and B component read signals, respectively, as amplifiers 3304, 3305, and 3306;
8-bit digital image signals 3313 (R), 331 for each color through sample hold circuits 3307, 3308, 3309 and A / D converters 3310, 3311, 3312.
4 (G) and 3315 (B).

FIG. 42 is a block diagram of the saturation judgment of the color judgment section 3211.

In FIG. 42, reference numeral 3301 denotes MAX / MI
N detectors 3302 to 3309 are selectors, 33
Numerals 10 to 3315 denote subtracters for input A and input B.
B is output. Reference numerals 3316 to 3323 denote comparators. For inputs A and B, 3316 and 3319 denote 2A> B, and 3317, 3320, 3322, and 3323 denote A>.
In the case of B, 3318 and 3321 output 1 when A> 2B, and output 0 in other cases. 3324-
3328 is an AND gate, 3329 is a NOR gate, 3
330 is a NAND gate.

In the above configuration, the MAX / MIN detector 3301 uses the circuit shown in FIG. In FIG. 43- (a), 3350, 3351, 3352
Are comparators, and R> G, G> B, B>, respectively.
Outputs 1 in the case of R. As shown in FIG. 43- (b), the circuit shown in FIG.
0, S01, S02, S10, S11, S12 are generated. That is, when MAX is R or when R, G, and B are all equal, S00 = 1, S01 = S02 = 0,
When MAX is G, S01 = 1, S00 = S02 =
0, when MAX is B, S02 = 1, S00 = S01
= 0, MIN is R, or when R, G, B are all equal, S10 = 1, S11 = S12 = 0, MIN
Is G, S11 = 1, S10 = S12 = 0, MI
When N is B, S12 = 1 and S10 = S11 = 0.

For example, when MAX is R, since R> G and R ≧ B, the comparator 3350 outputs 1;
The comparator 3352 outputs 0. And AND1
Outputs 1 and OR1 outputs 1. AND2, AN
D3 outputs 0. That is, S00 = 1, S01 = S
02 = 0. FIG. 43-
It is a table shown to (b).

Outputs S00 and S0 of MAX / MIN detector
1, S02 are input to the selector 3302, and the output S1
0, S11, and S12 are input to the selectors 3303 to 3309.

The selectors 3302 to 3309 are shown in FIG.
As shown in (a), the circuit is composed of an AND circuit and an OR circuit.
According to this selector, as shown in FIG. 44- (b), A is output when S01 = 1, S1 = S2 = 0, and S1 = 1, S0 = S2 = When 0, B is output, and when S2 = 1, S0 = S1 = 0, C is output. In this embodiment, R, G, and B signals are made to correspond to inputs A, B, and C, respectively.

In the pixel color judgment of this embodiment, the maximum value of the R, G, and B signals is set to MAX, and the minimum value is set to MI.
N, and 4 of A, B, C, and D as shown in FIG.
This is done by dividing into two areas.

That is, in the achromatic region, MA
Taking advantage of the fact that the smaller the difference between X and MIN and the closer to the chromatic color, the larger the difference between MAX and MIN,
The MAX-MIN plane is divided by a linear simultaneous inequality using MAX and MIN as parameters.

Specifically, Ka, Kb, Kc, ia, i
b, ic, WMX, WMN are predetermined constants,
It is divided into four areas A, B, C, and D as shown in FIG.

A is a dark achromatic (black) area.
The condition in which (MAX, MIN) is included in this area is MIN ≦ WMN or MAX ≦ WMX, and

[0187]

[Outside 1] Is to meet all of

B is an intermediate region between a dark achromatic color and a chromatic color. The condition in which (MAX, MIN) is included in this area is MIN ≦ WMN or MAX ≦ WMX, and

[0189]

[Outside 2] Satisfy one of

[0190]

[Outside 3] Is to meet all of

C is a chromatic area. (MAX, MI
The condition in which N) is included in this area is that MIN ≦ WMN or MAX ≦ WMX, and

[0192]

[Outside 4] To satisfy any of the following.

D is a bright achromatic (white) area.
The condition that (MAX, MIN) is included in this area is as follows:

[0194]

[Outside 5] Is to satisfy both.

FIG. 45- (b) shows the output signals for the respective states A, B, C and D. That is,
In the case of being included in the A area, BL1 = 1, UNK1 = C
OL1 = 0, when included in the B area, UNK1 =
1, BL1 = COL1 = 0, when included in the C area, COL1 = 1, BL1 = UNK1 = 0, and when included in the D area, BL1 = 1, UNK1 = COL1 =
0.

The above-mentioned area determination is performed at 330 in FIG.
4 to 3330. MAX / MIN detector 33
The selectors 3302 and 3303 select the MAX signal and the MIN signal from R, G, and B in response to the output of 01, respectively.
3309 is also a constant ka, kb, kc, ia, i
Select the values of b and ic. For example, MAX is an R signal, MI
When N is a G signal, the selector 3304 outputs KAG, 33
05 is KBG, 3306 is KCG, 3307 is iAG,
3308 selects iBG, and 3309 selects iCG, and sets them as constants ka, kb, kc, ia, ib, and ic, respectively. Thus, the minimum value is a constant k depending on any of R, G, and B.
The values of a, kb, kc, ia, ib, and ic are changed for the following reasons.

In general, in the case of a full-color sensor, there is one of the color balances specific to the sensor, so that a chromatic / achromatic color determination for all colors based on the same determination criterion may cause an erroneous determination. Therefore, as shown in FIG.
By dividing the three-dimensional space of GB into three, it corresponds to the color balance characteristics of the sensor. That is, the three-dimensional space of RGB is divided into a region 3702 where MIN = R, a region 3703 where MIN = G, and a region 3704 where MIN = B, and corresponding ka, kb, kc, ia, ib,
Use the value of ic.

For example, for a sensor in which the signal of the R component appears lower, KAR, KBR, KC in FIG.
By slightly increasing the values of R, iAR, iBR and iCR, when MIN = R, FIG.
In the area shown in (a), the area A can be widened and the area C can be narrowed, and various sensors can be finely handled.

The subtractors 3310 to 3312 and the comparators 3316 to 3318 are provided with MAX-ka, 2MIN, MA
The magnitude relationship between X-kb and MIN and the relationship between MAX-kc and 1/2 MIN are determined.

The subtractors 3313 to 3315 and the comparators 3319 to 3321 are provided with MAX-ia and 2MIN,
MAX-ib and MIN, MAX-ic and 1/2 MIN,
Is determined.

The comparators 3322 and 3323 determine the magnitude relationship between MAX and WMX, and MIN and WMN, respectively.

From the above, the area determination is performed, and the result is output as a determination signal for BL1, UNK1, and COL1.

According to the present embodiment, the presence of the saturation determining means for switching the reference of the saturation determination in accordance with the result of the hue determination enables the saturation determination corresponding to the color balance characteristics of the reading sensor to be performed. / Effective for preventing erroneous color determination.

Further, the MAX-MIN space is defined as a chromatic color area,
Since the saturation determination is performed by finely distinguishing between a bright achromatic (white) region, a dark achromatic (black) region, and a chromatic and achromatic intermediate color region, the chromatic / achromatic determination becomes more accurate.

Further, since the area is sectioned linearly, the area can be determined by a simple inequality.

In this embodiment, the MAX-MIN space of the color component signal is divided into a plurality of regions as a criterion for determining the saturation.
It is not limited to the combination of MIN, for example, MAX
And average or MIN and average, MAX square root and M
Various combinations of parameters such as the square root of IN are possible.

Further, in this embodiment, 3 of RGB is used.
The dimensional space was divided into three parts.
It can be divided. Such fine division enables more appropriate determination processing to be performed.

Ninth Embodiment FIG. 47 is a block diagram for explaining a ninth embodiment. In FIG. 47, reference numerals 3301 to 303303 are the same as those in FIG. 3701 is a read-on memory (RO)
M) and the MAX signal, the MIN signal, S10, S11,
The S12 signal is input to the address. ROM370
In No. 1, data is programmed in advance to output determination results as shown in FIGS. 45A and 45B, and outputs BL1, UNK1, and COL1 are output.

According to the present embodiment, a determination result can be obtained without performing an operation each time a region is determined, and the time required for the determination can be reduced.

Further, the circuit configuration can be simplified.

In this embodiment, the ROM is used.
AM can be used in place of this.

Embodiment 10 FIGS. 48 and 49 are views for explaining the tenth embodiment.

FIG. 48 is a block diagram of the saturation judgment. In the figure, MAX and MIN are the same signals as those described in FIG. 1, and an adder 8001, subtractors 8002, 800
3, squarers 8004, 8005, multipliers 8006, 80
07, a decision signal J is generated via an adder 8008.
J is J = (MAX + MIN-a) ² × b + (MAX-M
IN) ² × c, calculated as 8003, 8006,
It is calculated according to the values of a, b, and c preset in 8007.

[0214] Here a, b, by selecting appropriate values of _{c, J 1 <J = J} 1 and becomes a curve and J = J ₂ curve in J ₂ becomes appropriate constant as shown in FIG. 49 Indicated by an elliptic curve. Thus the value of J in the judgment circuit 8009 is compared with J ₁ and J _2, can be determined similarly to FIG. 45- (a).

According to the present embodiment, the use of the elliptic curve for the area division allows the area division to have more flexibility than the case of using a straight line.

Note that the area can be divided by any other linear or non-linear equation, such as a hyperbola, a parabola, etc., without being limited to the elliptic curve of this embodiment.

Embodiment 11 FIGS. 50 and 51 are views for explaining the eleventh embodiment. FIG. 50 is a block diagram of the saturation judgment, and FIG.
It is a figure showing the B space.

In FIG. 50, the difference from FIG.
304, 3305, 3306, 3307, 3308, 3
309 indicates that S00, S01, and S02 indicating the MAX signal are input as select signals. According to the present embodiment, as shown in FIG.
001, space 5002 such that MAX = G, MAX =
In each case of space 5003 that is B, ia, i
Each value of b, ic, ka, kb, and kc can be switched.

Embodiment 12 FIG. 52 is a diagram for explaining a twelfth embodiment, and is a processing block diagram of a saturation judgment.

9001 is (R, G, B) to (Y, I,
Q) An arithmetic unit for calculating (I, Q) in space.

[0221]

[Outside 6] (I, Q) is calculated by the following equation. Since the hue can be determined by (I, Q), the ROM 900 is determined in advance.
2 is programmed with the determination result, the selector 33
Switching signals of 04 to 3309 can be output.

In this embodiment, (I, Q) is used.
Is (L^* , A^* , B^* ) Space (a ^* , B^* ) And that
Signals representing other chromaticities can also be used.

Switching of selectors by hue is also possible.
Not only the street but also 6 streets and 12 streets can be used.

Further, a MAX signal or a combination of a MAX signal and a MIN signal can be used as a selector signal.

Embodiment 13 FIGS. 53 to 56 are views for explaining the thirteenth embodiment.

FIG. 53 is a block diagram showing the structure of this embodiment. Reference numeral 3101 denotes a first detecting means, and 3102 denotes a second detecting means.

Here, the first detecting means 3101 is the hue judging means described in the eighth embodiment, and in response to the R, G, B signals input for each pixel, the pixel is a dark achromatic color, that is, black. A second determination means 310 outputs a BL1 signal indicating that there is, a COL1 signal indicating that the color is a chromatic color, and a UNK1 signal indicating that the color is between a dark achromatic color and a chromatic color.
Send to 2.

The second judging means 3102 corrects the judgment result of the pixel based on the judgment result of the peripheral pixel group of the 5 × 5 matrix (FIG. 55) centering on the judgment target pixel, and makes the pixel dark. A BL signal indicating an achromatic color, that is, black, and a COL signal indicating a chromatic color are output.

That is, the present embodiment has a configuration in which a chromatic / achromatic determination signal is output by performing more appropriate determination on the output of the hue determining means of the eighth embodiment.

FIG. 54 is a block diagram of the second judging means 3102. BK1, C determined by the first determination means
OL1 and UNK1 signals are stored in the line memories 7001 and 7
002, 7003, 7004
Synchronized by HSYNC signal and CLK signal, 5
Lines are output simultaneously. Here, BK1, COL
1 and UNK1 delayed by one line
K2, COL2, UNK2, two lines delayed BK3, COL3, UNK3, three lines delayed BK4, COL4, UNK4, four lines delayed BK5, COL5, UN
55, black pixels are counted by the counting means 7005 to obtain NB in a 5 × 5 area as shown in FIG. 55, and chromatic pixels are counted by the counting means 7006 to obtain N.
Get C. Further, the number NB of black pixels and the number NC of chromatic pixels in the 5 × 5 block are compared by the comparator 7007.

Further, the gate circuits 7008, 7009, 7
010, 7011, and 7012, the outputs BK3, COL of the first determination means for the center pixel of the 5 × 5 area
3, a BL signal indicating that the center pixel is black and a COL signal indicating that the center pixel is chromatic are output. The criterion at this time is:
If the determination result of the first determination criterion is a black pixel and a chromatic pixel, the determination is not reversed. That is, BK3
= 1 or CO if COL3 = 1
Let L = 1. If the result of the first determination criterion is between a chromatic pixel and an achromatic pixel, NB and NC
Are compared, and when NB> NC, a black pixel is set and BL = 1
When NB ≦ NC, COL = 1 is output as a chromatic pixel. As a result, the uncertain intermediate area B shown in FIG. 45A can be accurately assigned to either the black area A or the chromatic area C.

The comparison between NB and NC can also be performed using a ROM as shown in FIG. In FIG.
The addresses of the ROM 7101 include NB and N as in FIG.
C, BK3, COL3, and UNK3 are input, and calculation results BL and COL stored in advance are output.

By using a ROM as described above, the circuit configuration can be simplified.

As described above, according to the color image processing apparatuses of the eighth to thirteenth embodiments of the present application, the input means for inputting a plurality of color component signals, Input means for inputting a plurality of color component signals, comprising: means for determining the hue of a pixel; and saturation determination means for switching a reference for saturation determination in accordance with the output of the hue determination means. Means for extracting a plurality of parameters indicating saturation by a combination from a chromatic area, a bright achromatic (white) area, a dark achromatic area, and an intermediate color area between chromatic and achromatic. Erroneous determination in the black-and-white / color determination is provided by having a determination unit that determines the saturation based on which of the determination target pixels belongs to the plurality of regions including the plurality of included regions. It is possible.

The invention according to the present application is not limited to a three-line sensor, and various image sensors such as an R, G, B dot-sequential line sensor and an area sensor (one using a solid-state image sensor or one using an imaging tube) And the like.

As the image output means, various output devices such as a laser beam color printer, a thermal transfer type color printer, an ink jet color printer, and a dot color printer can be used.

[0237]

As described above, according to the present invention, the black (monochrome) signal for the black area of the image is represented by the R (red) and B (blue) signals other than the G (green) signal among the three primary color signals. By using the G (green) signal without using it, it is possible to generate a black monochrome signal for a black region of an image with a simple configuration and with high accuracy.

[Brief description of the drawings]

FIG. 1 is a signal processing block diagram of a reading device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a delay memory and an interpolation operation.

FIG. 3 is a configuration diagram of a three-line parallel color sensor.

FIG. 4 is a configuration diagram of a reading device.

FIG. 5 is a processing flowchart of a microprocessor.

FIG. 6 is a diagram illustrating a reading operation.

FIG. 7 is a diagram illustrating the operation of the reading device.

FIG. 8 is a diagram showing a structure of a reading device.

FIG. 9 is a block diagram of a black area determination circuit according to the first embodiment of the present invention.

FIG. 10 is a block diagram of a black area correction circuit according to the first embodiment of the present invention.

FIG. 11 is a functional block diagram of a smoothing circuit according to the first embodiment of the present invention.

FIG. 12 is a diagram illustrating a configuration of max (R, G,
FIG. 4 is a diagram illustrating a black area in a (B) -min (R, G, B) space.

FIG. 13 shows the relationship between max (R, G, B) -min (R, G, B) of the input color original signal according to the first embodiment of the present invention.
Distribution map and max for the smoothed input color signal
FIG. 5 is a diagram illustrating a distribution diagram of (R, G, B) -min (R, G, B) and an example of a black character document.

FIG. 14 is a diagram illustrating a process from reproduction of an original black character to reproduction of a corrected black area according to the first embodiment of the present invention.

FIG. 15 is a diagram illustrating an example of OR signal processing according to the first embodiment of this invention.

FIG. 16 is a block diagram of color signal processing according to the first embodiment of the present invention.

FIG. 17 is a diagram illustrating another example of a three-line sensor.

FIG. 18 is a block diagram of a black area determination circuit according to a second embodiment of the present invention.

FIG. 19 is a block diagram of a chromatic pixel number counting circuit according to a second embodiment of the present invention.

FIG. 20 shows the values of max (R, G,
FIG. 4 is a diagram illustrating a chromatic region in a (B) -min (R, G, B) space.

FIG. 21 is a block diagram of a black area determination circuit according to a third embodiment of the present invention.

FIG. 22 is a diagram illustrating spectral sensitivity characteristics of the red, blue, and green color sensors.

FIG. 23 is a block diagram of a determination circuit according to a fourth embodiment of the present invention.

FIG. 24 is a diagram illustrating a storage state of a line buffer according to the fourth embodiment of this invention.

FIG. 25 shows (max (R, G,
FIG. 4 is a diagram illustrating a relationship between a B), min (R, G, B)) space and a chromatic color area.

FIG. 26 is a chromatic determination space diagram of a conventional example.

FIG. 27 is a distribution diagram of black character input data.

FIG. 28 is a processing flowchart of a microprocessor 2111 according to the fourth embodiment of this invention.

FIG. 29 is a diagram illustrating the relationship between the present invention and the overall configuration of image processing.

FIG. 30 is an overall configuration diagram of a color copying machine.

FIG. 31 is a block diagram of a determination circuit according to a fifth embodiment of the present invention.

FIG. 32 is a diagram illustrating a storage state of a line buffer according to a fifth embodiment of the present invention.

FIG. 33 is a processing flowchart of a microprocessor 2111 according to the fifth embodiment of the present invention.

FIG. 34 is a diagram illustrating a relationship between a color shift when a black character is read by a color sensor and a black character portion.

FIG. 35 is a block diagram of a determination circuit according to a sixth embodiment of the present invention.

FIG. 36 shows (max (R, G, G) of the sixth embodiment of the present invention.
FIG. 3B is a diagram showing a determination area in a (B), min (R, G, B)) space.

FIG. 37 is a block diagram of a determination circuit according to a seventh embodiment of the present invention.

FIG. 38 is a diagram showing a window of the line buffer according to the seventh embodiment of the present invention.

FIG. 39 is an edge determination unit 250 according to the seventh embodiment of the present invention.
1 is a processing circuit block diagram of FIG.

FIG. 40 is a processing flowchart of a microprocessor 2111 according to the seventh embodiment of this invention.

FIG. 41 is an overall configuration diagram of an eighth embodiment of the present invention and an internal block diagram of an image scanner unit.

FIG. 42 is a block diagram of saturation determination by a color determination unit 211.

FIG. 43 shows a MAX / MIN detection circuit and MAX / MIN
It is a figure explaining an output signal of a detector.

FIG. 44 is a diagram illustrating a circuit diagram of a selector and an output signal of the selector.

FIG. 45 is a diagram illustrating a determination condition and a diagram illustrating a determination signal.

FIG. 46 is a diagram illustrating an RGB color space.

FIG. 47 is a block diagram of saturation determination according to the ninth embodiment of the present invention.

FIG. 48 is a block diagram of saturation determination according to the tenth embodiment of the present invention.

FIG. 49 is a diagram showing determination conditions.

FIG. 50 is a block diagram of saturation determination according to an eleventh embodiment of the present invention.

FIG. 51 is a diagram illustrating an RGB hue space.

FIG. 52 is a processing block diagram of saturation determination according to a twelfth embodiment of the present invention.

FIG. 53 is a block diagram showing a configuration of a thirteenth embodiment of the present invention.

FIG. 54 is a block diagram of a second determination unit.

FIG. 55 is a 5 × 5 matrix used for a second determination unit.

FIG. 56 is a block diagram of a second determination unit.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 1/46-1/64 G06T 1/00 510

Claims (2)

(57) [Claims] An input means for inputting three primary color signals of R (red), G (green), and B (blue) according to an image, and a black area of the image is determined based on the three primary color signals. A black area determination unit that performs Bk (black) monochrome using the G (green) signal without using the R (red) and B (blue) signals other than the G (green) signal among the three primary color signals First generating means for generating a signal, Y ( yellow ), M based on the three primary color signals
Second generating means for generating (magenta), C (cyan) and Bk (black) signals; and generating by the first generating means for an area determined to be a black area by the black area determining means. Done Bk
(Black) a single-color signal is output, and the second area is determined by the black area determining means as an area that is determined not to be a black area.
A color image processing apparatus having an output means for outputting Y ( yellow ), M (magenta), C (cyan), and Bk (black) signals generated by the generating means. 2. An input step of inputting three primary color signals of R (red), G (green), and B (blue) according to an image, and determining a black area of the image based on the three primary color signals. A black area determining step of performing a Bk (black) single color signal using a G (green) signal without using an R (red) and B (blue) signal other than the G (green) signal among the three primary color signals And Y ( yellow ) and M based on the three primary color signals.
(Magenta), C (cyan), and Bk (black) signals, a second generation step, and an area determined as a black area by the black area determination step is generated by the first generation step. Done Bk
(Black) monochromatic signal is output, and the second region is determined for the region determined not to be a black region in the black region determination step .
Outputting an Y ( yellow ), M (magenta), C (cyan), and Bk (black) signal generated in the step of generating a color image.
How .