JP3105689B2 - Image processing apparatus and method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus and method capable of reading a color image and converting the image into an image that can be expressed by two colorants.

[0002]

2. Description of the Related Art There has been proposed a system in which a black-and-white printer is combined with a so-called reader for reading a color image. Then, among the input images, the black-and-white image is expressed as a gradation image, and a color-coded and other meaningful image such as a color graph,
For example, an image processing apparatus has been proposed in which an image as shown in FIG. 6 (a) is expressed by performing pattern division processing for each hue by combining oblique lines and dotted lines as shown in FIG. 6 (b).

FIG. 5 is a block diagram showing a control circuit of a conventional image processing apparatus.

[0004] Conventionally, R, G,
R (red), G (green), and B separated into three primary colors of light at B
The (blue) signals are first, second, and third smoothing processing circuits (smoothing circuits) 101, 102, and 103, respectively.
After the visual characteristics are corrected by the first, second, and third look-up tables (LUTs) 104, 105, and 106, they are input to the achromatic color determination circuit 107 and the hue determination look-up table (LUT) 108. You. The achromatic color determination circuit 107 calculates the difference between the maximum value and the minimum value of the R, G, and B signals, and determines whether the value is “1” if the value is equal to or less than a predetermined threshold, and “0” if the value is equal to or more than the predetermined threshold. And outputs the signal to the selector 112.
Is input to Also, the hue determination lookup table 10
8 outputs a hue angle tan (b / a) signal on the ab plane in the Lab coordinate space from the R, G, B signals, and outputs this tan (b
/ A) The signal is input to the pattern generator 110 via the authorized color determination circuit 109. Based on the hue angle tan (b / a) signal, the authorized color determination circuit 109 determines which registered color the hue belongs to. The pattern generator 110 generates a pattern signal corresponding to the hue determined by the authorized color determination circuit 109, that is, a signal that expresses a pattern for each color by combining diagonal lines and dotted lines. Is entered. On the other hand, the G signal is supplied to the fourth look-up table (LU
T) 111 and converted into a density signal, and then input to the selector 112. The selector 112 selects and outputs a density signal when the achromatic signal is “1” and a pattern signal when the achromatic signal is “0”.

[0005]

However, in the above-described conventional image processing apparatus, when the area of the smoothing process is widened, black characters in chromatic colors are not determined to be achromatic and black characters are not processed as characters. Conversely, when the area of the smoothing process is reduced, coarse color dots cannot be converted into a uniform pattern image. Further, for example, a black character in a chromatic color such as that shown in FIG. 7A is inconspicuous even if it is determined to be achromatic, because the black character is arranged on the pattern image as shown in FIG. 7B. was there.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to change a color according to a hue.
When converting to a turn image, halftone dots and thin lines in the original image
Unnatural patterning processing is applied to chromatic parts such as
It is an object of the present invention to provide an image processing apparatus and method capable of preventing a situation in which the image processing is performed.

[0007]

According to a first aspect of the present invention, there is provided an image processing apparatus, comprising: a smoothing means for smoothing an image signal of a non-black area in an original image; A hue discriminating unit that discriminates a hue of a chromatic region in the original image based on the image signal that has been smoothed by the first unit; and a first output unit that outputs a black region in the original image using black. A second output unit configured to convert a chromatic area in the original image into a pattern image in accordance with a result of the determination by the hue determination unit and output the pattern image using a single color other than black. Also, to achieve the same objective,
According to a second aspect of the present invention, in the image processing apparatus of the first aspect, the image processing apparatus further includes a boundary processing unit that adds an image to a boundary between the achromatic region and the chromatic region in the original image. I do. In order to achieve the above object, an image processing apparatus according to claim 3 is characterized in that, in the image processing apparatus according to claim 1 or 2, the single color other than black is red.

[0008] In order to achieve the above-mentioned object, according to claim 4,
The image processing method uses an image signal of a non-black area in the original image.
A smoothing step for smoothing, and
The original image based on the smoothed image signal.
A hue determination step of determining the hue of the chromatic color area in the middle,
Do not perform the smoothing process on the black area in the original image
A first output step of outputting, and a chromatic color area in the original image.
A pattern corresponding to the determination result of the hue determination step
And a second output step of converting the image into an image and outputting the image.
And features.

[0009]

In the image processing apparatus according to the present invention, the smoothing means smoothes the image signal of a non-black area in the original image, and the hue determining means based on the image signal smoothed by the smoothing means. To determine the hue of the chromatic area in the original image,
A first output unit that outputs a black area in the original image using black;
The second output means converts the chromatic color area in the original image into a pattern image according to the result of the determination by the hue determination means, and outputs the pattern image using a single color other than black. In the image processing apparatus according to the second aspect, the boundary processing means adds an image to a boundary between the achromatic region and the chromatic region in the original image. In the image processing apparatus according to the third aspect, the single color other than black is red.

Further, the image processing method according to claim 4 is a
The smoothing step flattens the image signal in non-black areas in the original image.
Smoothing, and the hue determination step
Chromatic color in the original image based on the smoothed image signal
The first output step determines the hue of the area,
Output without performing the smoothing process on the area, and output the second
The step is to determine the chromatic area in the original image
The image is converted into a pattern image according to the determination result and output.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to FIGS.

[First Embodiment] An image processing apparatus according to a first embodiment reads R, G, and B signals as three primary color signals,
FIG. 1 shows an apparatus capable of processing and outputting an achromatic portion excluding a white portion to a black (first) coloring material and an chromatic portion to an image that can be represented by a red (second) coloring material. FIG. 3 is a block circuit diagram showing a control circuit configuration of the device.

In FIG. 1, reference numeral 1 denotes a luminance discriminating circuit for discriminating luminance, and reference numerals 2, 3, and 4 denote first, second, and third smoothing processes.
The third smoothing circuits 5, 6, 7 correct the R, G, B luminance signals smoothed by the first to third smoothing circuits 2 to 4 so as to match the visual characteristics.
Third look-up table (LUT), 8 is R, G, B
An achromatic color determination circuit that determines an achromatic color based on a difference between a maximum value and a minimum value of a signal; 9 is a hue determination lookup table (LUT) that determines an angle on an ab plane in a Lab coordinate space;
0 is a registered color discriminating circuit for discriminating to which of the colors the color belongs in advance, 11 and 12 are first and second comparators, 13, 14 and 21, 22, 23, respectively.
Is an AND circuit; 15, 16, and 17 are first 9 × 9 OR circuits that take a logical sum in the respective areas, and first 3 × 3 OR circuits
Circuits and a second 3 × 3 OR circuit, 18, 19 and 25 are XOR circuits, 20 and 35 are NOT circuits, 24 is an OR circuit, 26 is a NAND circuit, and 27 is a color determined by the certified color determination circuit 10. In this embodiment, a pattern generator for generating a predetermined pattern signal colored with a red coloring material, 28 is a red solid pattern (red border) signal, and 29 is a white pattern signal (Open) pattern generators for generating signals, 3
0, 31, 32, 36, and 37 are multipliers, and 33 is a fourth lookup table (LU) for converting a luminance signal into a density signal.
T) and 34 are adders.

Next, a description will be given of the principle of operation of the present apparatus for performing different coloring processes on the boundary between the black portion and the chromatic portion and the boundary between the white portion and the chromatic portion using two colorants.

The input R, G and B signals are input to the luminance discriminating circuit 1 respectively. The luminance discriminating circuit 1 calculates a minimum value of the R, G, and B signals and a difference between the maximum value and the minimum value of the R, G, and B signals, and outputs a discrimination signal for determining the luminance. The R, G, B signals are simultaneously
The signals are also input to the third smoothing circuits 2 to 4, respectively.
Then, the first to third smoothing circuits 2 to 4 change the smoothing coefficient in the smoothing process based on the determination signal, and when the circuit 1 determines that the luminance is dark,
For example, when it is determined that the image is not dark without performing the smoothing process, for example, the smoothing process of 5 × 5 pixels is performed. First
Third to third look-up tables (LUTs) 5 to 7 correct the smoothed R, G, and B luminance signals so as to match the visual characteristics. The corrected R, G, B signals (hereinafter, referred to as “corrected RGB signals”) are output to the achromatic determination circuit 8.
And the hue determination LUT 9. The achromatic color determination circuit 8 calculates the difference between the maximum value and the minimum value of the corrected RGB signal, and outputs an achromatic signal of “1” when the difference value is equal to or less than a predetermined threshold and “0” when the difference value is equal to or more than the predetermined threshold. Output.

On the other hand, the hue determination LUT 9 outputs a hue angle tan (b / a) signal for the corrected RGB signal. Based on the hue angle tan (b / a) signal, the certified color determination circuit 10 determines which registered registered color belongs to which color. The G signal is also supplied to the second smoothing circuit 3 and the second LU
The first comparator 11 and the second comparator 1 are respectively connected via T6.
2 is input. The first comparator 11 outputs a bright portion determination signal of “1” when the G signal is equal to or higher than a predetermined threshold, and “0” when the G signal is equal to or lower than the predetermined threshold. Is “1” at the time, and “0” is at least the predetermined threshold.
Is output. The AND circuit 13 takes the logical product of the bright part determination signal and the achromatic color determination signal described above,
Outputs a white determination signal. The AND circuit 14 calculates the logical product of the dark part determination signal and the above-described achromatic color determination signal, and outputs a black determination signal. The black determination signal is input to a first 9 × 9 OR circuit 15 and a first 3 × 3 OR circuit 16, and the white determination signal is input to a second 3 × 3 OR circuit 17.

The first 9 × 9 OR circuit 15 outputs a current pixel (hereinafter, referred to as a “target pixel”) to a black determination signal of all 9 × 9 = 81 pixels around the target pixel. An OR operation is performed. If at least one of the pixels has a black determination signal of “1”, the output signal of the first 9 × 9 OR circuit 15 becomes “1”, and the black determination signals of all the pixels become “1”. When it is “0”, the output signal of the first 9 × 9 OR circuit 15 becomes “0”. Similarly, the first 3 × 3 OR circuit 16
Takes the logical sum of all 3 × 3 = 9 pixels around the pixel of interest with the black determination signal.

The XOR circuit 18 has a first 9 × 90 circuit.
The exclusive OR of the output signal of the R circuit 15 and the output signal of the first 3 × 3 OR circuit 16 is calculated. The XOR circuit 18 outputs “1” when there are no pixels determined to be black in a 3 × 3 pixel area around a target pixel and there are pixels determined to be black in a 9 × 9 pixel area. That is, when the target pixel is separated by four pixels from the pixel determined to be black, the output signal becomes “1”. Also, the first 3 × 3 OR circuit 16
Is 1 from the pixel whose target pixel is determined to be chromatic and black.
When the pixel is separated, that is, when the pixel is adjacent to the pixel determined to be black, the output signal becomes “1”.

Further, an AND circuit 21 outputs an inverted signal of an achromatic color determination signal input through a NOT circuit 20 and the XO signal.
The logical product with the output signal of the R circuit 18 is calculated. That is, when the target pixel is four pixels away from the pixel determined to be chromatic and black, the output signal of the AND circuit 21 becomes “1”. Similarly, the output signal of the AND circuit 22 becomes “1” when the target pixel is one pixel away from the pixel determined to be chromatic and black.

The output signals (boundary determination signals) from these AND circuits 21 and 22 are applied to XOR circuits 25 and O
Each is input to the R circuit 24.

The second 3 × 3 OR circuit 17 performs a logical OR operation on the target pixel with the white determination signals of all 3 × 3 = 9 pixels around the target pixel. If there is a pixel whose signal is “1”, the output signal of the second 3 × 3 OR circuit 17 becomes “1”, and when the white determination signals of all the pixels are “0”, the second 3 × 3 OR circuit 17 The output signal of No. 17 is "0". XOR circuit 1
Reference numeral 9 indicates that when the target pixel is one pixel away from the pixel determined to be white, that is, when the pixel of interest is adjacent to the pixel determined to be black, the output signal is “1”. Further, the AND circuit 23 outputs N
The logical product of the inverted signal of the achromatic determination signal input via the OT circuit 20 and the output signal of the XOR circuit 19 is calculated. That is, when the target pixel is one pixel away from the pixel determined to be chromatic and white, the output signal of the AND circuit 23 becomes “1”. The output signal (boundary determination signal) from the AND circuit 23 is input to the multiplier 31.

The multiplier 31 outputs to the adder 34 a signal obtained by multiplying the output signal from the AND circuit 23 by the solid red pattern signal from the solid red pattern generator 28.

The XOR circuit 25 is connected to the AND circuit 21.
Of the output signal of the AND circuit 23 and the output signal of the AND circuit 23, and the signal (exclusive OR signal) is output to the multiplier 32.
Output to The multiplier 32 outputs to the adder 34 a signal obtained by multiplying the exclusive OR signal by the white pattern signal from the white pattern signal generator 29.

The NAND circuit 26 is connected to the AND circuit 2
The logical product of the output signal of the AND circuit 23 and the output signal of the AND circuit 23 is obtained, and the output signal is output to the multiplier 30.
The multiplier 30 outputs a signal obtained by multiplying the output signal of the NAND circuit 26 and the pattern signal from the pattern generator 27 to the adder 34.

As described above, the logical sum is obtained by the OR circuits 15 to 17 and the exclusive OR is obtained by the XOR circuits 18 and 19 based on the output signals. Determine if there is. And
By taking the logical product of the inverted signal of the achromatic color determination signal and the input signals of the AND circuits 21 to 23, it is determined at which position on the boundary between the chromatic color and the achromatic color the target pixel is located.

On the other hand, the G signal is converted by the LUT 33 into a density signal. Further, when the achromatic determination signal input via the OR circuit 24 is "1", the multiplier 36 selects this density signal, and an image is displayed with a black (first) coloring material. When the output signal of the AND circuit 22 input through the above-described OR circuit 24 is “1”, that is, when there is a pixel determined to be black next to the chromatic color, the multiplier 36 outputs this density signal. The selected line is displayed as a thick line colored with a black coloring material at the boundary between the chromatic color and the black portion.

On the other hand, when the achromatic judgment signal input via the OR circuit 24 is "0" and the signal is inverted by the NOT circuit 35 and is "1", the multiplier 37 outputs the signal to the adder 34. In this embodiment, an image is displayed in a predetermined pattern, a solid red pattern, or a white pattern corresponding to the hue colored with the red (second) coloring material.

Actually, in the case of a sample which is classified into a black portion, a chromatic portion and a white portion as shown in FIG. 2A, as shown in FIG. With the image of the predetermined pattern colored with the coloring material, the black part is displayed by the black image, and the white part is displayed by the white image, and the boundary between the chromatic color and black is indicated by a thick black line. Further, the boundary between the thick line and the chromatic portion is displayed by a white image, and the boundary between the chromatic color and the white portion is displayed by an image of a solid red pattern.

As shown in FIG. 3A, in the case of a sample in which 40%, 30%, and 25% black characters are displayed on red, yellow, and green chromatic portions, respectively,
As shown in FIG. 3B, the chromatic portion is displayed as an image in a predetermined pattern colored with a red coloring material corresponding to each hue, and the background of the black character portion is outlined, so that the black character can be easily seen. The image is displayed.

[Second Embodiment] Next, a second embodiment of the present invention will be described with reference to FIG.

FIG. 4 is a block circuit diagram showing a control circuit configuration of an image processing apparatus according to a second embodiment of the present invention.

In the figure, reference numeral 51 denotes a luminance discriminating device for discriminating luminance, and 52 to 54 denote first to third pixels for performing a smoothing process.
Smoothing circuits 55 to 57 are first to third look-up tables (LUTs) for correcting the R, G, B signals smoothed by the first to third smoothing circuits 52 to 54 so as to match the visual characteristics. Reference numeral 58 denotes an achromatic color determination circuit that determines an achromatic color from a difference between the maximum value and the minimum value of the R, G, and B signals; 59, a hue determination lookup table (LUT) that determines an angle on the ab plane in the Lab coordinate space; Reference numeral 60 denotes a certified color discriminating circuit for discriminating which color belongs to a pre-registered color, and 61 denotes a visually corrected LUT 5
First and second computing units 62 and 63 for computing visual luminance based on RGB signals of 5 to 57 are first and second comparators, respectively.
Reference numerals 64, 65 and 79 to 84 denote AND circuits, and reference numerals 66 to 71 denote logical sums in respective areas.
9 is a first and second 7 × 7 OR circuit, 67 and 70 are first,
The second 5 × 5 OR circuit, 68 and 71 are the first and second 3 × 5 OR circuits.
A 3OR circuit, 72 to 77 are XOR circuits, 78 is a NOT circuit, and 85 is a pattern that generates a pattern according to the color determined by the authorized color determination circuit 60 and uses red (second coloring material).
A pattern generator that generates a predetermined pattern according to the determined hue, 86 is a fourth look-up table (LUT) for converting a luminance signal into a density signal, and 87 and 88 are ANDs
The second and third calculators 89 to 91 for calculating the multipliers according to the degree of separation of the boundary between the chromatic and achromatic colors from the respective boundary position signals of the circuits 79 to 84 are the first to third, respectively.
The multipliers 92 and 93 are first and second adders.

In the above configuration, the input R, G, and B signals are input to the luminance determination circuit 51, respectively. The luminance discriminating circuit 51 calculates the minimum value of the R, G, and B signals and the difference between the maximum value and the minimum value of the R, G, and B signals, respectively, and outputs a discrimination signal for determining the brightness. The R, G, and B signals are also simultaneously input to the first to third smoothing circuits 52 to 54, respectively. First to third
The smoothing circuits 52 to 54 perform smoothing processing on the R, G, and B signals by changing the smoothing coefficient in the smoothing processing according to the determination result of the luminance determination circuit 51. The discrimination signal output from the luminance discrimination circuit 51 is used only for changing the smoothing coefficient and does not affect other processes.

The first to third LUTs 55 to 57 correct the smoothed R, G, and B luminance signals so as to match the visual characteristics. The corrected R, G, B signals (hereinafter referred to as “corrected RGB signals”) are input to an achromatic color determination circuit 58 and a hue determination look-up table (LUT) 59.

The achromatic determination circuit 58 calculates the difference between the maximum value and the minimum value of the corrected RGB signal in the pixel, and sets "1" when the difference value is equal to or less than a predetermined threshold value and "0" when the difference value is equal to or more than the predetermined threshold value. Output an achromatic color determination signal. That is, if the corrected R, G, B signals have substantially the same level, it is determined to be achromatic, and if there is a difference between the levels of the corrected R, G, B signals, it is determined to be chromatic.

On the other hand, the hue judgment LUT 59 has a correction RGB
The signal outputs a hue angle tan (b / a) signal on the ab plane in the Lab coordinate space corresponding to the signal. The certified color determination circuit 60 determines the hue from the value of the hue angle tan (b / a) signal, and determines which registered registered color belongs.

The first calculator 61 multiplies the corrected RGB signals at a ratio corresponding to the spectral characteristics of the human eye to generate a luminance signal. This luminance signal is input to the first comparator 62 and the second comparator 63, respectively. The first comparator 62 outputs a bright portion determination signal that is “1” when the luminance signal is equal to or higher than a predetermined threshold and “0” when the luminance signal is equal to or lower than the predetermined threshold. At this time, a dark portion determination signal which becomes “1” and becomes “0” when it is equal to or more than a predetermined threshold value is output. The AND circuit 64 calculates the logical product of the bright portion determination signal and the achromatic color determination signal output from the achromatic color determination circuit 58, and outputs a white determination signal. The AND circuit 65 calculates the logical product of the dark part determination signal and the achromatic color determination signal, and outputs a black determination signal.
The black determination signal is supplied to the first 7 × 7 OR circuit 66, the first 5
The × 5 OR circuit 67 and the first 3 × 3 OR circuit 68, and the white determination signal is supplied to the second 7 × 7 OR circuit 69 and the second 5 ×
The signals are input to the 5-OR circuit 70 and the second 3 × 3 OR circuit, respectively.

The first 7 × 7 OR circuit 66 calculates the logical sum of the target pixel and the black determination signals of all 7 × 7 = 49 pixels around the target pixel. If there is a pixel of “1”, the first 7 × 7
The output of the OR circuit 66 is “1”, and when the black determination signals of all the pixels are “0”, the output of the first 7 × 7 OR circuit 66 is “0”. Similarly, the first 5 × 5 OR circuit 67
Is the logical sum of all the 5 × 5 = 25 pixels around the pixel of interest with the black determination signal, and the first 3 × 3 OR circuit 68
Takes the logical sum of the 3 × 3 = 9 pixels around the target pixel with the black determination signal.

The XOR circuit 72 has the first 7 × 7
The exclusive OR of the output of the OR circuit 66 and the output of the first 5 × 5 OR circuit 67 is calculated. The XOR circuit 72 outputs “1” only when there is no pixel determined to be black in the 5 × 5 pixel area around the target pixel, but there is a pixel determined to be black in the 7 × 7 pixel area. . That is, "1" is output when the target pixel is separated by three pixels from the pixel determined to be black. Similarly, the XOR circuit 73 outputs “1” when the target pixel is separated from the pixel determined to be black by two pixels.
The XOR circuit 74 becomes “1” when the target pixel is one pixel away from the pixel determined to be black, that is, when the target pixel is located next to the pixel determined to be black.

Then, the AND circuit 79 is a NOT circuit 78
And the inverted signal of the achromatic color determination signal input through
The logical product with the output signal of the OR circuit 72 is obtained. That is, when the target pixel is three pixels away from the pixel determined to be chromatic and black, the AND circuit 79 outputs “1”. Similarly, the AND circuit 80 sets “1” when the target pixel is two pixels away from the pixel determined to be chromatic and black,
The ND circuit 81 outputs “1” when the target pixel is one pixel away from the pixel determined to be chromatic and black. Outputs (boundary determination signals) from the AND circuits 79 to 81 are input to the second arithmetic unit 87.

The second 7 × 7 OR circuit 69 performs a logical OR operation on the target pixel with the white determination signals of all 7 × 7 = 49 pixels around the target pixel. If there is a pixel that is “1”, the second 7
The output of the × 7 OR circuit 69 is “1”, and when the white determination signals of all the pixels are “0”, the second 7 × 7 OR circuit 6
9 is "0". Similarly, the second 5 × 5 OR circuit 70 calculates the logical sum of all the 5 × 5 = 25 pixels around the target pixel with the white determination signal, and the second 3 × 3 OR circuit 71 performs the logical OR operation around the target pixel. The logical sum of all 3 × 3 = 9 pixels with the white determination signal is calculated.

The XOR circuit 75 takes the exclusive OR of the output of the second 7 × 7 OR circuit 69 and the output of the second 5 × 5 OR circuit 70. The XOR circuit 75 has a 5
Only when there are no pixels determined to be white in the x5 pixel area, but there are pixels determined to be white in the 7x7 pixel area,
Outputs “1”. That is, it becomes “1” when the target pixel is separated by three pixels from the pixel determined to be white. Similarly, the XOR circuit 76 becomes “1” when the target pixel is separated by two pixels from the pixel determined to be white, and
The R circuit 77 becomes “1” when the pixel of interest is one pixel away from the pixel determined to be white, that is, when it is next to the pixel determined to be white.

The AND circuit 82 is a NOT circuit 78
XOR with the inverted signal of the achromatic color determination signal input through
The logical sum with the output signal of the circuit 75 is obtained. That is, when the target pixel is three pixels away from the pixel determined to be chromatic and white, the AND circuit 82 outputs “1”. Similarly, the AND circuit 83 sets “1” when the target pixel is two pixels away from the pixel determined to be chromatic and white,
The D circuit 84 outputs “1” when the target pixel is one pixel away from the pixel determined to be chromatic and white. Outputs (boundary determination signals) from these AND circuits 82 to 84 are input to a third arithmetic unit 88.

On the other hand, the pattern generator 85 generates a predetermined pattern corresponding to the hue based on the signal sent from the authorized color discriminating circuit 60. The luminance signal output from the first computing unit 61 is a fourth look-up table (LUT).
86 converts it into a density signal.

When the inverted signal of the achromatic color determination signal is "0", that is, when the target pixel is determined to be an achromatic color by the achromatic color determination circuit 58, the third arithmetic unit 88 outputs the second multiplier 9
An output signal “0” is sent to the zero and third multiplier 91. When the inverted signal of the achromatic color determination signal is “1”, that is, when the pixel of interest is determined to be chromatic, AN
A signal corresponding to the boundary determination signal transmitted from the D circuits 82 to 84 is transmitted.

More specifically, the third arithmetic unit 88 performs AND circuits 82 to 84 based on the inverted signal of the achromatic color determination signal.
Are all near the boundary, the multiplier 0 is multiplied by 0 to the second multiplier 90 and the third multiplier 9
The multiplier 1 is transmitted for one. The AND circuit 82
Is "1", the multiplier 0.25 for the second multiplier 90 and the multiplier 0.7 for the third multiplier 91.
5 is sent. If the output signal of the AND circuit 83 is “1”, the multiplication factor 0.5
To the third multiplier 91.
Further, if the output signal of the AND circuit 84 is “1”,
The multiplier 1 is sent to the second multiplier 90 and the multiplier 0 is sent to the third multiplier 91.

In this way, the third computing unit 88 outputs the second
The multiplied numbers sent to the multiplier 90 and the third multiplier 91 are output to the second and third multipliers 90 and 91 by the fourth LU.
Density signal and pattern generator 85 sent from T86
The predetermined pattern signal colored with the red coloring material sent from the above is multiplied by each and added by the second adder 93.

Thus, chromatic fine lines and the like in the white area are reproduced by the density signal. Further, processing is performed so that the boundary between the white portion and the chromatic portion gradually changes from a white portion to a predetermined pattern corresponding to a red hue (chromatic color).

On the other hand, when the inverted signal of the achromatic color determination signal is "0", the second arithmetic unit 87, that is, the achromatic color determination circuit 58
When the target pixel is determined to be an achromatic color, the output signal “1” is sent to the first multiplier 89 and the output signal “0” is sent to the third multiplier 91. When the inverted signal of the achromatic color determination signal is “1”, that is, when the target pixel is determined to be chromatic, a signal corresponding to the boundary determination signal transmitted from the AND circuits 79 to 81 is transmitted. More specifically, if the output signals of the AND circuits 79 to 81 are all “0” based on the determination signal of the achromatic color determination signal, the second arithmetic unit 87 is not near the boundary, so the first multiplier 89 And the multiplier 1 is sent to the third multiplier 91. If the output signal of the AND circuit 79 is “1”,
The multiplication factor 0.25 is sent to the first multiplier 89 and the multiplication factor 0.75 is sent to the third multiplier 91. Also, AND
If the output signal of the circuit 80 is “1”, the multiplication factor 0.5 is sent to the first multiplier 89 and the multiplication factor 0.5 is sent to the third multiplier 91. Further, if the output signal of the AND circuit 81 is “1”, the multiplication number 1
To the third multiplier 91. In this manner, the respective multipliers sent from the second calculator 87 to the first multiplier 89 and the third multiplier 91 are sent from the fourth LUT 86 in the first multiplier 89 and the third multiplier 91. Are multiplied by the density signal and the red predetermined pattern signal sent from the pattern generator 85, respectively.
The signals are output by the adder 92 and the second adder 93. As a result, the boundary between the black portion and the chromatic color portion becomes similar to the above-described processing performed on the boundary between the white portion and the chromatic color portion. (A chromatic color).

[0050]

As described above, the image according to claim 1 is provided.
According to the image processing apparatus, the smoothing means is not black in the original image
The image signal of the area is smoothed, and the hue determination means smoothes it.
The original image based on the image signal smoothed by the
The hue of the chromatic color area in the image is determined, and the first output means outputs the original image.
The black area in the image is output using black, and the second output means outputs the original image.
The chromatic color area in the image is converted to a pattern according to the result of the determination by the hue determination means.
Convert to turn image and output using a single color other than black
Therefore, when converting the original image to a pattern image,
Even if a chromatic area such as a halftone dot or a thin line exists in the
Different pattern images due to the influence of dots, thin lines, etc.
Or switch between the pattern image and the plain at a fine pitch
To prevent the output of non-uniform images
In addition, the black area in the original image can be
Image signal can be output without smoothing
You.

According to the image processing method of the fourth aspect,
For example, if the smoothing step performs
Signal, and the hue determination step is a smoothing step.
The original image based on the image signal smoothed in
The hue of the middle chromatic area is determined, and the first output step
Output without performing the smoothing process on the black area in the image
The second output step determines the chromatic color area in the original image
Converted to a pattern image according to the determination result of another step
Output, so when converting the original image to a pattern image,
Assume that chromatic areas such as halftone dots and thin lines exist in the original image
Is also affected by the halftone dots and fine lines.
At a fine pitch between images or between a pattern image and plain
Switching to output a non-uniform image.
Can be stopped, and the black area in the original image is
Area image signals can be output without smoothing
it can.

For an image in which an achromatic portion such as a black character exists in a chromatic portion, the boundary between the two can be made clear so that the black character can be read easily.

If a thin line of chromatic color exists in the achromatic portion (white portion), the thin line of the second coloring material (for example, (Red solid pattern processing in the example), and a color image of the document can be faithfully reproduced.

Further, for example, the boundary between the colors may be blurred and the color may naturally move without clearly distinguishing the boundary between the black portion and the chromatic color or the boundary between the white portion and the chromatic color. It can be processed into a so-called gradation image.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a control circuit of an image processing apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating an example in which image processing is performed by the image processing apparatus in FIG. 1;

FIG. 3 is a diagram illustrating an example of image processing performed by the apparatus.

FIG. 4 is a block diagram illustrating a control circuit of an image processing apparatus according to a second embodiment of the present invention.

FIG. 5 is a block diagram illustrating a control circuit of a conventional image processing apparatus.

FIG. 6 is a diagram illustrating an example in which image processing has been performed by the image processing apparatus in FIG. 5;

FIG. 7 is a diagram showing an example of image processing performed by the apparatus.

[Explanation of symbols]

2, 3, 4, 52, 53, 54 First to third smoothing circuits (smoothing coefficient changing means) 8, 58 Achromatic color determining circuit (first determining means) 10, 60 Certified color determining circuit (hue angle processing means) 13, 14, 64, 65 AND circuit (second determination means) 21, 22, 23, 79, 80, 81, 82, 83, 8
4 AND circuit (recognition means) 25 XOR circuit (boundary coloring processing means) 26 NAND circuit (boundary coloring processing means) 38 OR circuit (boundary coloring processing means) 87,88 Operation circuit (boundary coloring processing means)

──────────────────────────────────────────────────の Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 1/38-1/393 H04N 1/40-1/409 H04N 1/46-1/64

Claims (4)

(57) [Claims] An image signal of a non-black area in an original image is flattened.
A smoothing means for performing a smoothing process , based on the image signal smoothed by the smoothing means,
And a hue for determining a hue of a chromatic area in the original image.
Determining means, and a first output means for outputting a black area in the original image using black
And a step for determining the chromatic color area in the original image by the hue determination means.
Use a single color other than black by converting it to a pattern image
And a second output means for outputting the image data. 2. The image processing apparatus according to claim 1, further comprising a boundary processing unit for adding an image to a boundary between the achromatic region and the chromatic region in the original image. 3. The method according to claim 2, wherein the single color other than black is red.
3. The image processing apparatus according to claim 1, wherein 4. An image signal of a non-black area in an original image is flattened.
A smoothing step for smoothing, and an image signal smoothed in the smoothing step
The hue of a chromatic area in the original image based on
Hue discriminating step, and without performing a smoothing process on a black area in the original image.
A first output step of outputting a chromatic color area in the original image,
Second output to convert to a pattern image according to another result and output
An image processing method comprising: