JP3155751B2 - Image processing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus that records a color image using a recording material (ink toner or the like) of a plurality of colors, such as a color copying machine and a color fax.

[Conventional technology]

When color recording is performed by additive color mixing based on the color-separated image signals, black thin lines and characters are generally recorded by superposing Y, M, C, or Y, M, C, and K4 recording materials.

[Problems to be solved by the invention]

However, when three or four colors of recording material are superimposed, the superimposed colors do not appear completely black, and do not appear black because it is difficult to accurately superimpose them. The problem is that it cannot be expressed in high resolution because it cannot be recorded continuously. For monochrome images, thin lines and characters in the image are distinguished and separated from other halftone image parts, and only the former is recorded at high resolution to express both gradation and resolution of the image at the same time. Proposed by the applicant.

However, this method solves the above-mentioned problem, but has the disadvantage that independent hardware is required for each color to be applied to a color image, and the black signal is identified from the color signal, for example, one of them is used. The method of judging a region that coincides with the character portion extracted from the color G component as a black character region has problems that it is difficult to identify the black portion accurately and inexpensively and that both regions are difficult to match exactly. leave. Also, the so-called black signal generated by masking and UCR is used to correct only black that can be expressed by C, M, Y. Especially in black character thin line parts, there is not enough level, so it can be used for this kind of processing Absent.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-described problems, and has as its object to provide an image processing apparatus that can satisfactorily reproduce a color image, particularly, a black thin line in the color image.

It is another object to provide an image processing apparatus having a simplified circuit configuration.

It is another object to provide an image processing device suitable for high-speed processing and real-time processing.

[Means and actions for solving the problem]

Therefore, the present invention provides an input unit that inputs a plurality of color separation signals corresponding to an image, and obtains a color separation signal indicating a maximum value and a color separation signal indicating a minimum value among the plurality of color separation signals,
A black line drawing signal determination of a value obtained by adding a signal corresponding to a signal indicating a value obtained by subtracting the color separation signal indicating the minimum value from the color separation signal indicating the maximum value and the color separation signal indicating the maximum value Generating means for generating a signal; first determining means for determining whether or not the pixel of interest of the image belongs to a black line drawing portion based on the black line drawing determination signal; A second determination unit that determines whether or not the pixel belongs to a portion adjacent to the black line drawing unit; and if the first determination unit determines that the pixel of interest belongs to the black line drawing unit, Is emphasized, the color component of the color image signal corresponding to the target pixel is suppressed, and the second determination unit determines that the target pixel is a portion adjacent to the black line drawing portion. If it is determined, the target pixel Kicking and having a control means for controlling to suppress the color component of the color image signal corresponding to the image.

〔Example〕

FIG. 1A is a block diagram showing the entire embodiment of the present invention. In the figure, reference numeral 1 denotes a color CCD line sensor which separates substantially the same point of a document into three colors of R, G, and B and quantizes the same into 8 bits for each color. The R,
The G and B signals are input to the color processing unit 2 and subjected to so-called color signal processing such as logarithmic conversion, masking, UCR, and γ conversion to obtain recording signals of Y, M, C, and K each of which is a recording color of 8 bits. The recording signals are subjected to so-called pseudo halftone processing in the binarizing units 3-1, 3-2, 3-3, 3-4, respectively. On the other hand, the color-separated R, G, B signals are input to a black signal generator 6 which is a feature of the present invention,
A black signal d having 8-bit 256 levels and suppressed color is generated. The black signal is binarized by a binarizing unit 7 with high definition. The binarized signal is input to a black character discriminating unit 8 and separated from a continuous halftone portion and a halftone image portion to separate a character / thin line portion. The identification and separation are performed, and the identification result signal is input to the recording signal control unit 4. The control unit controls the binary signals of the four colors independently binarized as described above based on the identification signal, and drives the recording element 5.

Now, the embodiment of the present invention will be described in detail in the order of the black signal generation unit 6, the binarization unit 7, the identification unit 8, and the binary data control unit 4. Note that the color signal processing unit 2 and the binarizing unit 3 will not be described because all known techniques can be applied.

(Black Signal Generation Unit) FIG. 2 (a) shows a black signal generation unit. In the figure, a maximum value detection unit 61 and a minimum value detection unit 62 each have an RGB represented by 8 bits.
The level of the signal is compared for each pixel, and the largest value and the smallest value of the level are obtained as max (RGB) min (RGB), respectively. The adder 63 calculates the difference max (RGB) −min (RG
B) is calculated, and the result is multiplied by a predetermined constant α in a multiplier 66 and added to max (RGB) in an adder 64. When the addition result exceeds the 8-bit width by a limiter (limiter) 65, the addition result is limited to 255 to obtain a black signal d.

FIG. 2B is an explanatory diagram of this processing. In this embodiment, the greater the value of each of the color signals R, G, and B, the whiter, that is, R
When = G = B = 0, black is assumed. Therefore, in FIG. 2 (b), the portion A is a thin line B having a color, and the portion B is a black line.

d = max (RGB) + α [max (RGB) −min (RGB)] (max (RGB) is a gray component signal, max (RGB) −min (RG
(B) is a signal indicating color, α is a color suppression constant.) The physical meaning of this processing is that max (RGB) -min (RGB) is regarded as color and max (RGB) is a gray component (brightness). Then, when max (RGB) -min (RGB) is large, that is, at a point having a color, the value can be converted to a brighter (white) direction by multiplying this value by a constant α and adding it to max (RGB). Therefore the constant α
Α is referred to as a color suppression constant as a value representing the degree to which the tint is suppressed so that a point having a tint becomes a whiter point as the value of is larger. That is, the degree of the black component detection indicated by d can be changed by changing the value of α set in the multiplier 66 by the CPU (not shown). In FIG. 2 (b), α = 1 is shown, but max (RGB) is large and max (RG
B) When -min (RGB) is large, the limiter 6 shown in FIG.
5 gives a maximum value of 255 representing a perfect white point. Therefore, it is considered that the change in the generated signal d substantially means a change in the black component.

The black signal d is input to the binarizing unit 7 shown in FIG.

<Binarizing Unit> In FIG. 3, the data for one line of the black signal d is delayed and held by the memory 71 using the memory 71, and the data of five pixels sequentially line-delayed are added by the adder 72. Further, the adder 75 adds the five adder values obtained by delaying the adder by the F / F 73 for each pixel. The output of the adder is delayed by two pixels from the input data, that is, the memory 71-
If the output position of the F / F73-6 delayed by two outputs by the F / F73-5 and 736 is set as the target pixel position, it is an integrated value of 25 pixels around the output position. For example, the average value m of the black signal in the vicinity of the pixel of interest is obtained.

The comparator 79 compares the data d at the pixel position of interest with the average value m as a threshold value to obtain a finer binary signal B.

That is And

Further, a difference between the average values m and d is obtained by an adder 77, converted into an absolute value by an absolute value circuit 78, and then compared with a constant δ by a comparator 74 to obtain a binary signal C.

That is And

The physical meaning of both signals is that the former B is a signal obtained by binarizing the black signal with high definition, and the latter C is a signal obtained by binarizing the level change amount at the target pixel. That is, when B = 1 and C = 1, it can be determined that the density change at the target pixel is larger than the constant δ and changes in the black direction. That is, it can be said that there is a high probability that this point is a part of the character thin line.

However, since the pixel of interest may be a halftone image portion represented by a halftone dot, the same two-bit signal is input to the black character identification unit 8 to identify the character portion in order to remove the halftone dot.

<Black Character Recognition Unit> FIG. 4 shows the black character recognition unit. First, the input binary signal B is successively delayed and held line by line using line memories 80-1, 80-2, 80-3, and 80-4, and flip-flops 81-0 to 81-9 are used for each pixel. Hold delayed. Therefore, if the target pixel position is the F / F81-4 output position, the binary data B of the eight pixels adjacent to the target pixel is F / F81
-2, 81-4, 81-6 and F / F 81-2, 81-
9, 81-3, 81-5, and 81-7 output terminals, and the nine adjacent pixel data including the target pixel are all gate circuit 83-2.
Is input to

Similarly, the gate circuit 83-1 has pixel data one line after the target pixel, that is, nine points adjacent to the output position of the F / F 81-2, and the gate circuit 83-4 has one pixel from the target pixel.
Data of 9 points before the line, that is, adjacent to the F / F81-6 output position, is input. In the gate circuit 83, whether or not the center point is inverted from the eight binary levels (0 or 1) of the eight adjacent points, that is, the center point is isolated from the periphery and "0" Alternatively, a value S of 0 to 4 is assigned to each pixel depending on whether or not the pixel has the level of “1”. It can be said that the larger the value S is, the greater the possibility of a halftone pixel is, and conversely, if the value S is 0, it is more likely to be a part of a character or the like. This is because a character line is a set of one-dimensionally continuous dots. However, since it is not always possible to judge whether a character is a single point or not, the value S indicating the isolation assigned to each pixel is two-dimensionally integrated and determined. That is,
Multi-value data indicating the degree of isolation is used for the determination. First, the adder 85-1 adds three pixels in the line direction, holds the result delayed by six pixels in the F / Fs 84-1 to 84-6, and adds them in the adder 85-2 to obtain input image data B. If a pixel delayed by two lines and four pixels is used as the target pixel position, an added value Pf of data S for 3 × 7 pixels centered on the target pixel is obtained. The feature amount Pf means a two-dimensional spatial frequency. In other words, the larger the Pf value is, the more the value of the binary data B is "0" or "1" in the vicinity of the target pixel, that is, the spatial frequency is high, and therefore the dots are two-dimensionally isolated. Means

Therefore, the Pf value is set to a predetermined constant K (about 4 to 5) and the comparator 86.
And the target pixel position, that is, the memories 80-5 and 80-5
-7, the binary signal C and the binary signal B at the same position delayed by 4 pixels at the F / Fs 82-1 to 82-4 and the binary signal B at the same position are 87 output values E = 1. Some points.

One line from the signal E and the pixel position of interest and F / F89-1 to
The signal B delayed by two pixels by 2 is input to the black character signal generator 88 to generate black character signals KB and KW which are final outputs.

Now, the inside of the gate circuit 83 will be described in detail. FIG. 5 is a diagram showing the gate circuit 83, and a, b, c, d, e, f, g, and h adjacent to the central pixel i are the input / output signals B of the F / F 81 described above. EX-OR gate 831−
1, 831-2 detects whether or not the target pixel i is inverted in the a, i, and h directions. That is, if both EX-OR gate outputs are “1”, the output of the AND gate 832-1 becomes 1, and the target pixel i is isolated in the aih direction. Similarly, the EX-OR gates 831-3 and 831-4, and the AND gate 832-2 are in the cif direction, EX
-OR gates 831-5 and 831-6, AND gate 832-3 are big
Direction, EX-OR gates 831-7, 831-8, AND gate 832-
Reference numeral 4 detects the isolation in the die direction. Here AND gate 833
-1, 833-2, and the OR gate 834 detect the case where the target pixel i is continuously at the same level "0" or "1" in the big direction or the die direction. 0 ". The signal is ANDed with the outputs of the AND gates 832-1 to 832-4 described above by the AND gates 835-1 to 835-4, and the output result is added by the adder 836 to obtain S indicating the value of 0 to 4. .

The physical meaning of the condition by the AND gate 833 and the OR gate 834 is likely to be a part of a character because its continuity is a line segment orthogonal to the paper surface (document or recording paper surface). Accordingly, in this case, S = 0 is uniquely set, and as a result, the feature amount Pf is reduced. The area to be integrated as the Pf value is preferably 7 ×
Characters having a rectangular shape of about 7 and wider than in this embodiment can identify characters with high accuracy. However, the block size block shape is not limited to the above-described example, and can be appropriately set according to detection accuracy and the like.

Next, the inside of the black character signal generator 88 will be described in detail with reference to FIG. The processing part is KB = 1 (1 bit) indicating one part of black characters
An object is to generate a signal and a pixel position signal KW = 1 (1 bit) adjacent to the signal and adjacent to a black character with B = 0. The aforementioned 1-bit signals E and B are input, and the E signal is line-delayed and further delayed for each pixel by F / F880-1 to 880-5, so that the target pixel position is set to the output position of F / F880-3. The gate 881 has one of eight pixels adjacent to the pixel of interest.
When = 1, "1" is obtained at the output. Therefore, the B signal is converted to F / F880
After delaying at -7 and adjusting to the target pixel position, invert and AND
When input to the gate 882, a KW signal is obtained. Same signal KB and K
The recording signal control unit 4, which is a feature of the present invention that controls the recording signal by the W signal, will be described in detail.

<Recording signal control unit> In order to generate the above-described black character signals KW and KB, the internal processing is delayed by 5 lines and several pixels with respect to the binary data. Adjust to The memories 40-1 to 40-4 in FIG. 7 constitute a delay circuit for that, and the binary recording signals KB and KW are Control like That is, the black recording signal is 2K signal and KB =
In addition, when the color recording signal is recorded at the same position with the OR with 1, the color recording is stopped and suppressed in order to avoid color mixture. Also KW
= 1 signal pixel can be recorded more clearly by suppressing the color recording signal and stopping the recording dot around the black character.

 The relationship between KB, 2K, KW and dot recording is shown in Table 1 below.

<Recording Device 5> Next, the configuration of the recording device 5 of FIG. 1A will be described.

The present invention provides ink jet recording, thermal transfer recording,
It is applicable to various recording methods such as electrostatic recording. Here, an example in the case of using for ink jet recording will be described.

FIG. 10 is a perspective view around the head of an ink jet recording apparatus using a heating element.

In the figure, reference numeral 51 denotes a head unit, which is a total of four nozzles 52.
Have a book. That is, the head unit 51 has the black ink discharge nozzle 52K, the yellow ink discharge nozzle 52Y, the magenta ink discharge nozzle 52M, and the cyan ink discharge nozzle 52C. 53 is an ink supply tube, and 54 is a main tank provided with four main tanks corresponding to each nozzle.

The configuration of the nozzle 52 will be described with reference to the cross-sectional view of FIG.
55 is an upper plate, 56 is a bottom plate, 57 is a generating element, 58 is an orifice portion, and 59 is ink.

When a voltage is applied to the heating element 57, heat is generated, and bubbles are formed around the element 57. When the voltage application is completed, the bubbles shrink. The ink near the orifice portion 58 is ejected from the orifice portion 58 in accordance with the formation and contraction of the bubble.

The recording head causes a state change such as film boiling in the ink by thermal energy to generate air bubbles (bubbles), and the ink is discharged from the discharge ports (nozzles) toward the recording material using the bubbles. This is a so-called bubble jet recording head for recording characters, images and the like.
In this recording head, the size of a heating resistor (heater) provided in each nozzle is much smaller than that of a piezoelectric element used for conventional ink jet recording, and high-density multiple nozzles are possible. High quality recorded images can be obtained, and it has characteristics such as high speed and low noise.

A recording device having a number of heads for one type of coloring material may be used.

In FIG. 12, reference numeral 101 denotes a head unit in which a large number of ink jet heads are arranged in the sub-scanning direction for one type of colorant, and has black, yellow, cyan, and magenta units. 107 is an ink tank for each head unit, 109 is a signal line, and 104 is a carriage drive motor for moving the carriage 105 with the head unit attached along the rail 103 in cooperation with the transport belt 105. 106 is a recording paper, 120 is a platen, 111 and 112 are recording paper transport rollers, 113 is a recording paper roll, and 114 is a guide roller. The head unit 101 is composed of a plurality of ink jet heads using the heating elements shown in FIG. 11, but of course, an ink jet head using electromechanical conversion means such as a piezo element can also be used.

<Another Embodiment (1) of Black Signal Generation Unit> FIG. 2 (c) shows another embodiment of the black signal generation. In the previous embodiment, the tint suppression constant is a constant value α irrespective of the gray component max (RGB), but the gray component is generally large, that is, the brighter the color component, the more often the tint is suppressed. Make it bigger. By doing so, a black signal d having higher contrast can be generated.

The value of β obtained by multiplying the value of max (RGB) −min (RGB) obtained by the adder 63 by the output max (RGB) of the maximum value detection unit 61 by the multiplier 661 and dividing the result by the constant β by the divider 662 is For example, about 128 is good. Further, the result is added to max (RGB) by the adder 64 and clamped to 255 by the limiter 65.

<Another Embodiment (2) of Black Signal Generating Unit> In the previous embodiment, the color was defined by the difference between max (RGB) and min (RGB), and the suppression was performed by an addition operation. RGB)
Alternatively, the suppression may be defined by a ratio of min (RGB) and the suppression may be defined by a multiplication operation on max (RGB). I mean Here, the constant γ is preferably about 63. According to the above equation, the larger the gray component is, that is, the brighter the gray component is, the more effective the suppression of the tint is.
(RGB) and min (RGB) are both reduced when they are small.
Even when the black component has a slight color tint, the value of d does not increase and a black signal d with higher contrast can be generated. In the embodiment of FIG. 2D, first, a constant γ is added to the output of the minimum value detecting section 62 by the adder 663, and the output of the maximum value detecting section 61 is divided by the divider 664. Then max (RGB) in multiplier 665
Multiply by

As described above, the algorithm for generating the multi-valued data in which the tint is suppressed from each of the R, G, and B data is not limited to the present invention, and is not particularly limited to the primary color RGB. Needless to say, the same effect can be obtained by using other color component signals.

<Another Embodiment (1) of Print Data Control Unit> In the above-described embodiment, an example in which print data is controlled after binarization has been disclosed. However, binarization will be described with reference to FIGS. 1 (b) and 8. An example of controlling the previous multi-value data will be described.

In FIG. 1 (b), the data converted into C, M, Y, K4 color signals by the color signal processing unit is output to the black character signal generation unit 8 described above.
After being controlled by the 2-bit signals KW and KB, the binarization unit 3 binarizes and records. In the case of the present embodiment, when the recording element 5 is a thermal recording element capable of density recording of dots, such as an LBP or a piezo-type ink jet printer or a thermal transfer printer in which the dot size can be modulated in multiple steps by pulse width modulation. The value conversion unit 3 is not always necessary, and the controlled multi-value data may be used for recording as it is.

Now, the inside of the recording signal control unit will be described in detail with reference to FIG. In FIG. 8 (a), memories 91, 92, 93 and 94 constitute a delay circuit for adjusting the positions of the black character signals KW and KB in the same manner as described above. , 9
Multi-level data is directly converted by 7,98 LUTs.

In the case of the black signal K, when KB = 1, the input data is emphasized in the black direction as shown in FIG. 8 (c), and the color signals C, M and Y are reversed as shown in FIG. 8 (b). A γ table that emphasizes in the white direction is selected and used.

When KW = 1, the degree of enhancement of the color signals C, M, Y is slightly reduced as compared with the case of KB = 1. In the present embodiment, in order to control the multi-value level, especially when KW = 1, the periphery of a black character having a ground color can be controlled to a light color as natural as possible, so that a higher quality recorded image can be obtained.

When KB = 1, it goes without saying that CK = 255 and CM, CC, CY = 0 may be set regardless of the input data.

<Another Embodiment (2) of Print Data Control Unit> In the above-described embodiment, black character processing was performed after masking UCR. However, as shown in FIG.
Similar effects can be obtained by controlling the B signal. The recording data control unit 10 in FIG. 1C will be described in detail with reference to FIG.

In FIG. 9 (a), the same delay memory as in the previous embodiment is used.
101, 102, 103 are 91, 92, 93, 94 in the embodiment shown in FIG.
However, in the present embodiment, a memory for one color is not required, so that the memory can be realized with a simpler configuration. Data conversion is performed by LUT conversion using ROMs 104, 105, and 106 for each color.

When KW = 1 as shown in FIG. 8 (c), each color is emphasized in the white direction, and when KB = 1 as shown in FIG. 8 (d), the color is emphasized in the black direction. Normal masking, UCR
When KW = 1, both Y, M, C, and K are emphasized in the white direction. Conversely, when KB = 1, the K signal is emphasized in the black direction, whereas the C, M, and Y signals are white. Emphasized in the direction. In both of the above embodiments, the conversion characteristic is not limited to a linear characteristic. If a non-linear characteristic is provided, the input signal becomes blacker when KB = 1 and KW =
In the case of 1, the color signal can be controlled to be whiter.

As described above, according to the above embodiment, black characters and fine lines in an image can be identified at low cost and with high accuracy.
Therefore, it is possible to print a character portion with high resolution in a single black color, and it is possible to print a black character clearly in black even if a color shift occurs at the time of printing.

In particular, according to the present embodiment, a black signal is extracted, and a thin line portion and a halftone image portion are identified based on the black signal. Therefore, it is not necessary to newly generate a black signal for identification, and the circuit configuration is reduced. Can be easy.

As a printer for outputting the recording signal generated as described above, a printer capable of color recording, such as a color ink jet printer, a color thermal transfer printer, a color dot printer, and a color laser beam printer, can be used.

In particular, the present invention is effective for a printer using a head that discharges liquid droplets by utilizing film boiling caused by thermal energy as shown in US Pat. Nos. 4,723,129 and 4,740,793.

Further, the above-described arithmetic circuit may be configured using a ROM, a RAM, or the like, or may be realized by software of a computer capable of performing the above-described arithmetic.

In addition, image data may be input from a CCD sensor, input from a host computer via an interface, or input from a memory.

〔The invention's effect〕

As described above, the present invention provides an input unit for inputting a plurality of color separation signals corresponding to an image, and obtaining a color separation signal indicating a maximum value and a color separation signal indicating a minimum value among the plurality of color separation signals. A black line drawing of a value obtained by adding a signal corresponding to a signal indicating a value obtained by subtracting the color separation signal indicating the minimum value from the color separation signal indicating the maximum value and the color separation signal indicating the maximum value. Generating means for generating a signal determination signal; first determining means for determining whether or not a pixel of interest of the image belongs to a black line drawing portion based on the black line drawing determination signal; A second determination unit that determines whether the pixel belongs to a portion adjacent to the black line drawing unit; and if the first determination unit determines that the pixel of interest belongs to the black line drawing unit, When the black component of the color image signal corresponding to the image is emphasized, The color component of the color image signal corresponding to the target pixel is suppressed, and when the target pixel is determined to be a portion adjacent to the black line drawing portion by the second determination means, Control means for controlling a color component of a color image signal corresponding to an image to calculate a plurality of color separation signals, obtain a luminance signal V and a color difference signal IQ, and calculate the color difference signal IQ. The black line image determination signal can be generated by a simple operation using a plurality of color separation signals, compared to a method of generating a signal for determining a black line image by determining the achromatic signal W. As a result, the circuit scale for generating the black line drawing determination signal can be reduced, the amount of calculation can be reduced, and the processing speed can be improved.

Furthermore, since the color other than the black line drawing portion of the image, for example, the pixels having the tint in the base portion can be emphasized so as to approach the white pixels and the color can be suppressed, the base portion of the image and the black line drawing portion can be suppressed. Since the difference can be made clear, simply obtain the color separation signal indicating the maximum value and the color separation signal indicating the minimum value among the plurality of color separation signals, and obtain the color separation signal indicating the maximum value and the minimum value. A black line drawing determination signal capable of determining a black line drawing portion with higher accuracy than a signal generating a signal for determining a black line drawing from the difference between the color separation signals indicating the above can be generated.

Furthermore, since the color component of the color image signal corresponding to the image is suppressed for the portion adjacent to the black character portion,
It is possible to reproduce a good black line drawing part in which the difference from the base part of the image is clarified.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of an embodiment of the present invention, FIG. 2 is a diagram showing black signal generation, FIG. 3 is a diagram showing a binarization unit, FIG. FIG. 5 is a diagram showing a circuit for halftone dot determination, FIG. 6 is a diagram showing a black character signal generating unit, FIG. 7 is a diagram showing a recording signal control unit, FIG. 8 and FIG. FIG. 10, FIG. 11, FIG. 12, and FIG. 12 are diagrams illustrating a recording apparatus. 6 Black signal generation unit 8 Black character identification unit

 ──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-1-227573 (JP, A) JP-A-63-263974 (JP, A) JP-A-1-135268 (JP, A) JP-A-2- 140057 (JP, A)

Claims (1)

(57) [Claims] An input unit for inputting a plurality of color separation signals corresponding to an image; obtaining a color separation signal indicating a maximum value and a color separation signal indicating a minimum value among the plurality of color separation signals; A black line drawing signal determination signal of a value obtained by adding a signal corresponding to a signal indicating a value obtained by subtracting the color separation signal indicating the minimum value from the color separation signal indicating the maximum value and the color separation signal indicating the maximum value Generating means for generating, from the black line drawing determination signal, first determining means for determining whether or not the target pixel of the image belongs to a black line drawing portion; and A second determination unit that determines whether or not the pixel belongs to a portion adjacent to the line drawing unit; and if the first determination unit determines that the pixel of interest belongs to the black line drawing unit, While enhancing the black component of the corresponding color image signal, The color component of the color image signal corresponding to the pixel of interest is suppressed, and if the pixel of interest is determined to be a portion adjacent to the black line drawing portion by the second determination means, the color component of the image in the pixel of interest is determined. Control means for controlling the color components of the color image signal to be suppressed.