JPH1042152A - Picture processor and picture processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inexpensively correct the space frequency characteristic of edge emphasis or the like while the deterioration of picture quality is suppressed by distributing the emphasis quantity of an edge part to a luminance signal and a chroma signal in accordance with a saturation component. SOLUTION: The three color component signals R1 , G1 and B1 are inputted to a first color space conversion means 102 and are converted into a luminance signal L1 showing brightness and chroma signals (Ca1 and Cb1 ) showing a color tone. A delay means 103 delays signals for N lines for the luminance signal L1 and signals for N/2 lines for the chroma signals (Ca1 and Cb1 ). The luminance signal L1 is inputted to an edge emphasis quantity extraction means 113 and edge emphasis quantity ε is extracted. The chroma signals (Ca1 and Cb1 ) are inputted to a color saturation quantity extraction means 114 and a color saturation signal S showing the brightness of the colors is generated. Edge emphasis quantity ε is inputted to an edge emphasis quantity distribution means 116 and it is distributed to the edge emphasis correction quantity εl of the luminance signal L1 and the edge emphasis correction quantity εl of the chroma signals (Ca1 and Cb1 ) in accordance wit the size of the color saturation signal S.

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, and more particularly to an image processing apparatus and method for performing correction processing of a spatial frequency characteristic on an input image signal.

[0002]

2. Description of the Related Art An example of a conventional color image processing apparatus is shown in FIG.
2 will be described below. In FIG. 12, reference numeral 101 denotes a color image input unit such as an image reader unit of a color copying machine, which outputs three-color separation signals R1, G1, and B1 that are separated into RGB for each pixel of the color image. The three-color separation signals R1, G1, and B1 are output from the achromatic / chromatic color determination unit 1.
201, and determines whether the pixel is a black-and-white pixel (achromatic color) or a color pixel (chromatic color).
Output C.

The G1 signal of the three-color separation signal is input to a character / image determination unit 111, and its pixel is a line image such as a character or a thin line or a continuous tone image such as a photographic image or a print image. And outputs a character / image determination signal TI. The character / image determination signal TI is input to the spatial filter coefficient storage unit 112. When the corresponding pixel is a character signal, the character spatial filter coefficient 1301 shown in FIG. 13 is used. When the corresponding pixel is an image signal, the image spatial filter coefficient shown in FIG. Coefficient 1302
Select

Hereinafter, a conventional spatial filter processing such as edge enhancement will be described. FIG. 13 shows a 5 × 5 pixel spatial filter coefficient 1301 and a spatial filter coefficient 1 for an image.
FIG. Character spatial filter coefficient 1301
Are determined so that edge enhancement larger than that of the image coefficient 1302 is applied. The character or image spatial filter coefficient Kij selected according to the character / image determination signal TI is determined by the edge enhancement means 103-R, 10-R.
3-G, 103-B, and the three-color separation signals R1, G
1 and B1 are edge-emphasized, and R2, G2 and B2 are output.

FIG. 14 shows an example of the edge enhancing means 103-R. A dotted frame 1401 represents a data delay circuit in the edge emphasizing means 103-R.
The R signal input to 3-R is stored in the line memories 801 and 8
At 02, 803, and 804, four lines of image data are stored. The stored image data for a total of 5 lines of the 4 lines and the line of interest is sequentially transferred to the data (Xj1) of 5 pixels via a flip-flop for each line.
To Xj5) are extracted.

[0006] A total of 25 R signals (X
ji: 1 ≦ i ≦ 5) is then processed by the edge enhancement arithmetic circuit represented by the dotted frame 1402 to obtain the spatial filter coefficient (aj) corresponding to each pixel array represented by the dotted frame 1403.
i: 1 ≦ i ≦ 5, 1 ≦ j ≦ 5) and are added. At this time, a multiplier (1404-10
28) 25 and an adder of each multiplication result (1429 to
1452) 24 are required.

Although the conventional spatial filter processing for the R signal has been described above, the same applies to the G signal and the B signal.
The circuit scale is 12 lines (4 lines × 3 colors), 75 multipliers (25 × 3 colors), and 72 adders (24 × 3 colors). Next, the edge-enhanced three-color separation signals R2, G2, and B2 shown in FIG.
Density signals C1, M by performing logarithmic conversion on
1, Y1. The density signals C1, M1, and Y1 are then subjected to color processing such as generation of a black signal K, removal of undercolor, and color correction by the color correction unit 107.
2, Y2 and K2 are output.

When the target pixel is achromatic, the color correction means 107 determines the density signals C2, M2 and Y2 according to the determination signal KC which is the result of the determination by the achromatic / chromatic color determination means 1201.
Is set to C2 = M2 = Y2 = 0, and is converted to a pixel consisting of a single black color. Reference numeral 110 denotes a color image output unit, which comprises an image recording apparatus such as an electrophotographic or ink jet printer.

When the color image output means is a binary printer or the like, the density signals C2, M2, Y2 and K2 are converted by the binarization means 108 into binary pixels C3, M3, Y3 and K3. When the resolution of the image input from the color image input unit 101 and the resolution of the image output by the color image output unit 110 are different, the binary image C3
M3, Y3, K3 are subjected to resolution conversion processing by the smoothing / resolution conversion means 109, and C4, M4, Y4, K4
Is converted to In particular, when the resolution of the color image output unit 110 is higher than the resolution of the color image input unit 101, a smoothing process for smoothly interpolating the outline of the image is performed, and the result is printed and recorded by the color image output unit 110. .

[0010]

However, as described above, in the conventional edge enhancement of an image, the same configuration is used for the R signal (103-R), the G signal (103-G), and the B signal (10-G).
3-B) is provided for each signal. In particular, for the image signal from a color copier image reader unit using a CCD line image sensor as image input means, the above-mentioned 5 × 5 In order to perform the two-dimensional spatial filter processing of the pixel size, many line memories, multipliers and adders are required as described above, which imposes a heavy load on cost.

In terms of image quality, when the target pixel is an achromatic color, the above-described color correction means 107 determines the density signal C2, according to the determination result of the achromatic / chromatic color determination means 1201.
Since M2 and Y2 are set to C2 = M2 = Y2 = 0 and converted to a pixel consisting of a single black color, the density obtained by C2, M2 and Y2 is lost and the density is reduced. The present invention has been made in view of the above-described problems, and a first object of the present invention is to perform correction of a spatial frequency characteristic such as edge enhancement while suppressing deterioration of image quality, and relates to the correction. A second object of the present invention is to provide a color image processing apparatus capable of reducing an achromatic signal to monochromatic black without excessive or insufficient image density.

[0012]

In order to achieve the above object, the present invention comprises, for example, the following arrangement. That is, an image processing apparatus for performing a sharpness correction on an input image signal, comprising: an extraction unit configured to extract a chromaticity signal from a brightness signal of the input image signal; and an edge amount based on the brightness signal. Edge amount extraction means, saturation extraction means for extracting a saturation component based on the chromaticity signal, and edge amount extracted by the edge amount extraction means according to the saturation component extracted by the saturation extraction means Distributing means for distributing an enhancement amount of an edge portion based on the above to the lightness signal and the chromaticity signal, and edge enhancing means for correcting the brightness signal and the chrominance signal with the enhancement amount of the edge portion distributed by the distribution means And characterized in that:

[0013] For example, the input image signal is an RGB signal, and further comprises a converting means for converting the emphasized brightness signal and the chromaticity signal by the edge emphasizing means into an RGB signal. Alternatively, when the saturation component is large, the distribution ratio for chromaticity correction is higher than that for lightness correction, and when the saturation component is small, the distribution ratio for lightness correction is It is characterized in that distribution is made higher than that. Alternatively, the extraction means converts the input image signal into a brightness signal and a chromaticity signal including two components.

Further, for example, the image processing apparatus further comprises an achromatic / chromatic color judging means for judging whether the input image signal is a chromatic color or an achromatic color based on a chroma component extracted by the chroma extracting means. Alternatively, further, the lightness signal is delayed by N lines, and the chromaticity signal is delayed by N / 2.
It has a delay means for delaying the line.

Further, for example, the saturation extracting means performs spatial filtering of N / 2 + 1 lines on the chromaticity signal delayed by N / 2 lines by the delay means. Alternatively, the achromatic / chromatic color determination means performs spatial filtering of N / 2 + 1 lines on the chromaticity signal delayed by N / 2 lines by the delay means. Further, the distributing unit changes a distribution ratio of the image edge amount according to a saturation component of the saturation extracting unit and a determination result determined by the achromatic / chromatic color determining unit.

Further, generating means for generating a lightness signal and a chromaticity signal, extracting means for extracting a signal corresponding to a spatial frequency characteristic based on the lightness signal, and the lightness signal based on the signal extracted by the extracting means And control means for controlling a spatial frequency characteristic of the chromaticity signal. For example, the signal corresponding to the spatial frequency characteristic is a signal representing an edge amount of an image. Alternatively, the control means controls edge enhancement of the brightness signal and the chromaticity signal.

Further, a generating means for generating a lightness signal and a chromaticity signal, and a first means for extracting an edge amount based on the lightness signal.
Extracting means, a second extracting means for extracting a saturation component based on the chromaticity signal, and the lightness signal or the lightness based on the edge amount and the saturation amount respectively extracted by the first and second extracting means. Control means for controlling the spatial frequency characteristics of the chromaticity signal.

[0018] For example, the control means controls edge enhancement of the lightness signal or the chromaticity signal. Further, for example, the image processing apparatus further includes a determination unit that performs achromatic / chromatic color determination based on the saturation amount extracted by the second extraction unit, and the control unit determines the spatial frequency characteristic based on a determination result of the determination unit. The control is performed.

Further, generating means for generating a lightness signal and a chromaticity signal, delay means capable of delaying the lightness signal by N lines and delaying the chromaticity signal by N lines, and N means Extracting means for extracting an edge amount using the brightness signal delayed by the line, and (N / 2) the delay means according to the edge amount extracted by the extracting means.
Control means for controlling the spatial frequency characteristic of the chromaticity signal delayed by the amount of the line.

[0020] Further, there are provided generating means for generating a lightness signal and a chromaticity signal, and correcting means for performing a correction process of a spatial frequency characteristic on the chromaticity signal, wherein the correcting means comprises the lightness signal and the color signal. The correction processing is performed so that the hue of the image represented by the degree signal is stored before and after the correction processing. Reading means for scanning the original and generating an image signal representing the original; and a color original or a black-and-white original based on the image signal obtained by the first scanning of the original by the reading means. Determination means for determining whether or not the chromaticity signal is obtained by converting the image signal obtained by the first scanning of the original into a brightness signal and a chromaticity signal according to the determination result by the determination means. And processing means for fixing the value to a predetermined value.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) An embodiment of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a block diagram showing a configuration of a color image processing apparatus according to the first embodiment of the present invention. FIG.
In FIG. 12, the same components as those in FIG. 12 described above are denoted by the same reference numerals, and detailed description will be omitted.

In the figure, reference numeral 101 denotes a color image input means constituted by an image reader section and the like.
For example, it can be configured by an image input unit of various color image processing apparatuses including a reading device of a document image such as a color image scanner and an image input unit from a computer in a broad sense. The other 106, 107, 108, 1 in FIG.
Reference numerals 09, 110, 111, and 112 denote luminance / density conversion means (106), color correction means (107), and binarization means (10) which operate as described in the conventional example shown in FIG.
8), smoothing / resolution conversion means (109), color image output means (110), character / image determination means (111),
It is a spatial filter coefficient storage means (112).

The G1 signal, which is one of the three color separation signals R1, G1, and B1 of the color image read by the color image input means 101, is input to the character / image determination means 111, and the character / image determination means 111 It is determined whether the pixel is a line image such as a character or a thin line or a continuous tone image such as a photographic image or a print image. The character / image determination unit 111 outputs the determination result as a character / image determination signal TI.

The character / image determination signal TI is input to the spatial filter coefficient storage means 112. The spatial filter coefficient storage unit 112 stores a character spatial filter coefficient and an image spatial filter coefficient, and stores a character spatial filter coefficient when the corresponding pixel is a character signal and an image spatial filter coefficient when the corresponding pixel is an image signal. And outputs it as a spatial filter coefficient Kij for characters or images.

FIG. 2 shows an example of the spatial filter coefficient Kij stored in the spatial filter coefficient storage means 112 in the embodiment of the present invention. In FIG. 2, reference numeral 201 denotes a character spatial filter coefficient, and reference numeral 202 denotes an image spatial filter coefficient. Here, the spatial filter coefficient Kij for characters or images in the above-described conventional example and the spatial filter coefficient Kij for characters or images in the embodiment of the present invention are described.
The difference from this will be described. The spatial filter 1301 or 1302 for characters or images in the conventional example shown in FIG. 13 has a DC component of 1, whereas the spatial filter for characters or images in the embodiment of the present invention is one. Reference numerals 201 and 202 are greatly different in that the DC component is set to 0. That is, for an image flat portion having no edge component, the output J value after the spatial filter processing of the conventional example is output as the input image signal value, while the output J value after the spatial filter processing in the embodiment of the present invention is output. The difference is that the output value is configured to be 0.

On the other hand, three signals of three color separation signals R1, G1, B1 of the color image from the color image input means 101 are:
The color signal is input to a first color space conversion means 102 which can be called a color separation means, and is converted into a lightness signal L1 representing brightness and chromaticity signals (Ca1, Cb1) representing tint. The lightness signal L1 and the chromaticity signals (Ca1, Cb1) are measured colorimetrically.
^{CIE1976 (L * a * b *} ) 3 discoloration of the color space "L ^*, a
^* , B ^* or "CIE1976 (L ^* ,
u ^* , v ^* ) color space "may be a three-color change L ^* , u ^* , v ^* , and is not limited to that color space. An arbitrary color space determined more simply may be used.

An embodiment of a conversion formula for simply converting the three-color separation signals R, G, and B into lightness and chromaticity signals L1, Ca1, and Cb1 is shown by the following formula (1).

[0028]

L = (R + 2G + B) / 4 Ca = (R−G) / 2 (1) Cb = (R + G−2B) / 4 The brightness signal L1 and the color converted by the first color space conversion unit 102 The degree signal (Ca1, Cb1) is input to the delay unit 103, and a signal corresponding to N lines for the lightness signal L1 and a signal corresponding to N / 2 lines for the chromaticity signal (Ca1, Cb1) are delayed. More specifically, when performing a filter process of 5 × 5 pixels as shown in FIG. 2, signals for four lines for the brightness signal L1 and two half lines for the chromaticity signals (Ca1, Cb1) are obtained. It is stored, and the time until the stored signal is output from the output is delayed.

Although not shown in FIG. 1, the brightness signal L1 delayed by N lines by the delay means 103 is actually data of 4 lines delayed and a total of 5 lines of the current line. It is input to the edge enhancement amount extraction means 113. Then, the edge enhancement amount extraction means 113 uses the character or image spatial filter coefficient Kij selected by the character / image determination signal TI to obtain the edge enhancement amount ε.
Is extracted.

The data processing following the data delay will be described later in detail with reference to FIG. Next, the edge enhancement amount ε is input to the edge enhancement amount distribution means 116, and at the same time, the edge enhancement correction amount εl of the lightness signal L1 and the color It is distributed to the edge enhancement correction amount εc of the degree signals (Ca1, Cb1). On the other hand, the delay means 10
3, the chromaticity signals (Ca1, Cb1) delayed by
Although not shown in FIG. 1, it is actually data for two lines delayed and a total of three lines for the current line.
The chroma signal S is input to the chroma amount extracting means 114, and a chroma signal S representing the vividness of the color is generated.

A method of generating the saturation signal S from the chromaticity signals (Ca1, Cb1) according to the embodiment of the present invention will be briefly described below. Chromaticity signal (Ca1, Cb
1) is a signal (a ^* , b ^* ) in the aforementioned CIE1976 (L ^* a ^* b ^* ) color space or a CIE1976 (L ^* , u ^* ,
v ^* ) signal in the color space (u ^* , v ^* ), the saturation signal S is determined by the following equation (2).

[0032]

S = (Ca1 ² + Cb1 ² ) ^0.5 (2) More simply, the saturation signal S may be determined by the following equation (3).

[0033]

S = MAX (Ca1, Cb1) (3) Here, the function MAX (A, B) outputs the larger value of the variables A and B. In addition to the edge enhancement amount ε and the saturation signal S, the determination signal KC from the achromatic / chromatic color determination unit 115 is also input to the edge enhancement amount distribution unit 116. The achromatic / chromatic color determination unit 115 is the same as that of FIG.
Achromatic / chromatic color determination means 120 described in the description of FIG.
As in the case of No. 1, it is determined whether the pixel is black and white (achromatic color) or color (chromatic color), and a determination signal KC is output. Achromatic / chromatic color determining means 12 whose signal is an RGB signal
In contrast to 01, the input signal to the achromatic / chromatic color judging means 115 is the saturation signal S representing the vividness of the color. However, as described above, the saturation signal S
03, the chromaticity signal (Ca
1, Cb1) is input to the saturation extraction unit 114 and generated, so that the achromatic / chromatic color determination unit 115
May be input as the saturation signal S and the chromaticity signals (Ca1, Cb1) as its original signals (in that case, the signals are input to the saturation amount extracting means 114 in FIG. 1 (C
a1, Cb1) may be input to the achromatic / chromatic color determination unit 115 together with the saturation signal S. ).

Next, referring to FIG. 3, the delay means 103 and its peripheral means, ie, the edge enhancement amount extraction means 113 and the saturation amount extraction means 11 according to the embodiment of the present invention will be described.
4. The achromatic / chromatic color determination means 115 will be described in detail. The lightness signal L1 and the chromaticity signals (Ca1, Cb1) output from the first color space conversion means 102 are converted into four lines for the lightness signal L1 by the line memories 801 to 804 constituting the delay means 103.
5, 806, two lines for the chromaticity signal Ca1 and the line memory 8
05 and 806, signals for two lines are stored for the chromaticity signal Cb1.

Now, assuming that the center line is the j line, the j-2, j-1, j, j + 1 lines are stored for the lightness, and the lightness signals of five lines including the current line j + 2 are edge-emphasized. It is input to the quantity extraction means 113. Thus, the brightness is equivalent to that of the conventional example shown in FIG. On the other hand, for the chromaticity signal Ca1, the delay means 10
The line memories 805 and 806 store j and j + 1 lines, and the chromaticity signals Ca1 for three lines including the current line j + 2 are output from the chroma amount extracting means 114,
It is input to the chromatic color determination means 115. On the other hand, the chromaticity signal C
Similarly, b1 is input to the saturation amount extracting unit 114 and the achromatic / chromatic color determining unit 115. That is, in the embodiment of the present invention, the chromaticity signals Ca1 and Cb1 each require a line memory for two lines, that is, a total of four lines of memory, but the chromaticity signals Ca1 and Cb1 require a space. Since no filtering is performed, the chromaticity signals Ca1, C
The number of multipliers and adders required for b1 is zero.

Further, in the embodiment of the present invention, when calculating the saturation signal S and the achromatic / chromatic color determination signal KC,
The calculation method using the above equations (2) and (3) is represented by j, j
It is also conceivable to perform spatial processing using data for three lines of +1, j + 2 lines. For example, the saturation signal S can be obtained by averaging the saturation signals of adjacent pixels of 3 × 3 size, and representing the average value as the saturation signal S. Similarly, the achromatic / chromatic color determination signal KC can The determination result of the 3 × 3 size adjacent pixel may be statistically processed, and the result may be used as the achromatic / chromatic color determination signal KC and the representative value KC. It goes without saying that any of the above methods may be adopted.

Here, a method will be described in which spatial processing is performed to obtain a saturation signal S, and a determination signal KC is calculated based on the obtained saturation signal S. In this method, when the chroma signal S is small, the pixel is black and white (achromatic color), and when the chroma signal S is large, the pixel is
It turns out that it is a color (chromatic color). Therefore, for simplicity, the determination signal KC is determined by Expression (4) using a predetermined threshold value ρ.

[0038]

(When S <ρ) KC = achromatic color (4) (when ρ ≦ S) KC = chromatic color The following is input to the edge enhancement amount distribution means 116 in the embodiment of the present invention. Edge enhancement amount ε, saturation signal S,
A process of generating the edge enhancement correction amounts εl and εc based on the achromatic / chromatic color determination signal KC will be described.

First, the edge enhancement correction amount εl for the brightness signal L1 will be described. In this example, basically,
As the saturation is lower (closer to achromatic color), the distribution of the edge enhancement amount ε for the lightness signal is increased, and the entire edge enhancement amount ε is assigned to εl for the achromatic signal pixel. In addition, edge correction for a brightness signal is not performed on a pixel having a saturation equal to or higher than a predetermined threshold.

An edge enhancement correction amount generation process for an edge enhancement amount distribution lightness signal in the embodiment of the present invention will be described with reference to the flowchart of FIG. 4 and the schematic diagram of FIG. FIG. 4 is a flowchart showing an edge enhancement correction amount generation process for an edge enhancement amount distribution brightness signal in the embodiment of the present invention. FIG. 5 is an edge enhancement for the edge enhancement amount distribution brightness signal in the embodiment of the present invention. It is a schematic diagram showing a correction amount.

In STEP 1 of FIG. 4, first, an achromatic color /
The chromatic color determination signal KC is determined, and the process branches depending on whether the achromatic / chromatic color determination signal KC of the target pixel is achromatic or black. When the determination signal KC indicates an achromatic color (STEP in the figure)
1-YES direction), the entire edge enhancement amount ε is assigned to εl, and γ = 1. On the other hand, when the determination signal KC indicates a chromatic color (STEP1-NO direction in the figure), the process proceeds to STEP2, where the vividness of the target pixel is checked using the saturation signal S. If the target pixel is a predetermined threshold η
When the saturation is higher (YES in STEP2 in the figure), εl = 0, and no edge correction of the brightness signal is performed (γ =
0). This is based on an empirical rule in which, for pixels with high saturation, the edge effect by maintaining the brightness and increasing or decreasing the saturation is high.

On the other hand, in STEP 2, when the target pixel has a saturation lower than the predetermined threshold value η and has such a saturation that it is not determined to be an achromatic color (STEP 2 -NO in the figure)
Direction), and continuously connects εl = 0 and εl = ε according to the following equation (5) using a predetermined second threshold value α.

[0043]

５1 = (1− (S−α) / (η−α)) εγ = (1− (S−α) / (η−α)) (5) FIG. Is a diagram schematically showing the transition of, where the horizontal axis represents saturation and the vertical axis represents γ. From the saturation of 0 to the saturation value (threshold α) at which achromatic color is determined, εl = ε and γ = 1
It is. From the threshold values α to η, the saturation decreases continuously as γ = (1− (S−α) / (η−α)).

When the saturation is higher than the threshold value η, εl = 0 and γ = 0. Next, the edge enhancement correction amount εc for the chromaticity signals (Ca1, Cb1) will be described. Contrary to the case of the lightness signal, the higher the saturation (brighter the color), the greater the distribution of the edge enhancement amount ε to the chromaticity signal, Edge correction is not performed, and the chromaticity signal of the target pixel is also removed.

This is because, in the case of an image processing apparatus such as a color copying machine, the fact that color components remain in a copied image such as a black character has a very poor image quality visually. Therefore, it is necessary to cut color components for such pixels and perform color correction to complete achromatic signals. This will be described with reference to the flowchart of FIG. 6 and the schematic diagram of FIG. FIG. 6 is a flowchart showing generation of an edge enhancement correction amount for an edge enhancement amount distribution chromaticity signal according to the embodiment of the present invention, and FIG. 7 is an edge of the edge enhancement amount distribution chromaticity signal according to the embodiment of the invention. FIG. 4 is a schematic diagram illustrating an emphasis correction amount.

In STEP 1 of FIG. 6, first, an achromatic color /
The chromatic color determination signal KC is determined, and the process branches depending on whether the achromatic / chromatic color determination signal KC of the target pixel is achromatic or black. When the determination signal KC indicates an achromatic color (STEP in the figure)
1-YES direction), the edge enhancement amount ε is set to 0 (γ = 0) as described above. On the other hand, when the determination signal KC indicates a chromatic color (STEP1-NO direction in the figure), the process proceeds to STEP2,
The vividness of the target pixel is checked using the saturation signal S. If the saturation of the target pixel is higher than a predetermined threshold value λ (step 2-YES in the drawing), the total edge enhancement amount ε is set to εc
And εc = ε (γ = 1).

On the other hand, when the target pixel is a predetermined threshold value λ2
When the saturation is lower and the saturation is not determined to be an achromatic color (STEP2-NO direction in the figure), a predetermined second threshold value λ1 is used to switch between γ = 0 and γ = 1. The connection is continuously made according to the following equation (6).

[0048]

Γ = (S−λ1) / (λ2−λ1) (6) Further, the edge enhancement correction amount εc for the chromaticity signal is obtained according to the following equation (7).

[0049]

Εc = γ (1−ε / k) (7) FIG. 7 is a diagram showing the transition state of γ, in which the horizontal axis represents saturation and the vertical axis represents γ. From a saturation of 0 to a saturation value (threshold λ1) at which achromatic color is determined, εl = 0 city, γ =
0. When the saturation is between the thresholds λ1 and λ2, γ = (S−
(λ1) / (λ2−λ1), and continuously increases as the saturation increases. When the saturation is higher than the threshold λ2, εl = ε and γ = 1.

The edge enhancement correction amounts εl and εc generated as described above are input to the edge enhancement means 104 together with the L, Ca and Cb signals. Then, the edge enhancement means 104 adds the edge enhancement correction amount εl to the brightness signal L and multiplies the chromaticity signals Ca and Cb by the edge enhancement correction amount εc according to the following equation (8).

[0051]

L2 = εl + L1 Ca2 = εc ^* Ca1 (8) Cb2 = εc ^* Cb1 As can be seen from the equation (8), the saturation is increased by adding the edge correction amount ε1 to the signal L. Brightness can be preserved at pixels (εl = 0) for which edge edge enhancement is not desired.

On the other hand, the signals Ca and Cb are multiplied by the edge correction amount εc, and in particular, by multiplying εc = 0 for a pixel having low chroma and judged to be an achromatic color, the color of the target pixel itself is obtained. The degree component can be removed. Next, the preservation of color (hue) with respect to edge enhancement of the chromaticity signal will be described with reference to FIG. FIG. 8 shows a color (hue) for edge enhancement of a chromaticity signal according to the embodiment of the present invention.
FIG. 5 is a schematic diagram illustrating the storability of a chromaticity signal (C
a1, Cb1) represents chromaticity coordinates having the direction as a coordinate axis.

In the following, in order to simplify the explanation,
Ca and Cb axis and a ^*, b ^* axis in ^{CIE1976 (L * a * b *} ) color space. The intersection O of the a ^* and b ^* axes represents an achromatic color, and the further away from the intersection O, the higher the saturation ^.
The angle formed by the axis represents the color (hue). Now, when the target pixel is the chromaticity signals Ca1 (702) and Cb1 (703), this color is represented by a vector 701 on the chromaticity coordinates.

According to the equation (8), the chromaticity signals (Ca1, Cb)
1) Edge-enhanced signal (Ca2, Cb2) generated by multiplying edge correction amount εc = (εcCa1, εcCb)
1) is represented by a vector 704 on the chromaticity coordinates,
As shown in FIG. 8, the angle formed with the a ^* axis does not change, and the color (hue) is preserved before and after edge enhancement. That is, in this example, although the vividness is enhanced by the edge enhancement,
This indicates that there is no change in color.

The signals L2, Ca2, and Cb2 that have been edge-enhanced by the edge emphasis means 104 as described above are input from the edge emphasis means 104 to the second color space conversion means 105, and inversely converted again into RGB signals. . Equation (9) is obtained by converting the lightness and chromaticity signals L2, Ca2, Cb2 in the second color space conversion means 105 into three-color separation signals R2, G2, B2.
This is an expression showing an example of a conversion expression for converting into the expression (1), and is an inverse conversion coefficient of Expression (1).

[0056]

## EQU9 ## R = (4L + 4Ca + 2Cb) / 4 G = (4L-3Ca + 2Cb) / 4 (9) B = (4L + Ca-6Cb) / 4 Subsequently, it is input to the luminance / density conversion means 106 and converted into density signals C1, M1, and Y1. Density signal C1, M
1 and Y1 are then sent to the color correction means 107, where they are subjected to color processing such as generation of a black signal K, removal of undercolor and color correction, and output as density signals C2, M2, Y2 and K2.

In the embodiment of the present invention,
The determination signal KC, which is the determination result of the achromatic / chromatic color determination unit 115, and the determination signal TI, which is the determination result of the character / image determination unit 111, are black character / color character / image determination unit 117.
, Where it is determined whether the character is a black character, a color character, or an image. Black character / color character / image determination means 117
Is output as a black character / color character / image determination signal TC and input to the color correction means 107. Therefore, the color correction means 107 changes the color correction according to the black character / color character / image determination signal TC.

For example, for image signals, color correction is performed with emphasis on the color reproducibility of highlights, and for color characters and black character signals, color correction is performed by removing the highlight reproduction by skipping the background color. Similarly, the binarization unit 108 performs smoothing /
The resolution conversion means 109 also executes each processing while referring to the determination signal TI which is the determination result of the character / image determination means 111, and finally outputs the output image signals C4 and C4 from the smoothing / resolution conversion means 109. M4, Y4
K4 is sent to the color image output means 110, and the color image output means 110 prints out a color image.

As described above, according to the embodiment of the present invention, an edge amount for lightness is extracted, and the edge amount is distributed to a lightness signal and a chromaticity signal in accordance with a chroma component.
Perform edge enhancement correction, the edge enhancement means, when the image is determined to be achromatic by the achromatic chromatic color determination means,
By performing the correction for removing the chromaticity component from the chromaticity signal and realizing the black monochrome of the image, the required line memory in the edge enhancement correction can be greatly reduced as compared with the related art. What has been required can be constituted by eight lines, which can be reduced to 2/3 of the conventional value.

Further, in the above-mentioned example, in addition to the above,
The number of required multipliers can be reduced from 25 to 25, and can be reduced to 1/3, and the number of required adders can also be reduced to 24 from 72 in the conventional case. The circuit size can be reduced, and the circuit size can be significantly reduced. Further, by using the delayed chrominance signal by the delay means, spatial image processing can be realized on the chromaticity signal without newly providing a delay circuit, and when the target pixel is determined to be achromatic, the chromaticity signal By performing the correction that removes the chromaticity component, it is possible to reduce the cost load related to edge enhancement without deteriorating the image quality, and it is also possible to make black achromatic signals for achromatic signals without excessive or insufficient image density. As a result, the image quality can be improved.

(Embodiment of Second Embodiment) Hereinafter, FIG.
An embodiment of the second invention according to the present invention will be described in detail with reference to FIG. 9 described above with reference to FIG.
In the embodiment of the present invention, the same reference numerals are given to the same configurations as those of the embodiment, and the detailed description is omitted. The second embodiment differs from the first embodiment shown in FIG. 1 in that an original image color determining means 901 is further provided in the configuration of FIG.

In the second embodiment of the invention having the structure shown in FIG. 9, it is assumed that color image processing is performed in a color copying machine. A document color judgment to be determined in advance is performed.
When the original image color determination unit 901 determines in advance whether the original is a color original or a black-and-white original, an operation (prescan) of reading the entire original image in advance before reading the original for an actual copying operation is performed. When the pre-scan starts and the original image is read by the color image input means 101, the three-color separation signal R of each pixel of the read original image is read.
1, G1, B1 are input to the first color space conversion means 102, and the brightness signal L1 and the chromaticity signals (Ca1, Cb1)
Is converted to The chromaticity signals (Ca1, Cb1) are sent to the chroma amount extracting unit 114 via the delay unit 113, and the chroma amount is extracted by the chroma amount extracting unit 114, and the chroma signal S
Is output.

The saturation signal S of each pixel is input to the original image color determination means 901, and the saturation signal S is subjected to statistical processing on the entire original image to determine in advance whether the copy original is color or black and white. Saturation signal S by original image color determination means 901
As an example of the statistical processing, a method of taking a histogram of the saturation signal S for the entire original image and making a determination based on a threshold value can be considered.

FIG. 10 schematically shows an example of a histogram of the saturation signal S of a monochrome image document and a color image document. FIG.
In the black and white original image shown on the middle and upper sides, the accumulated pixels 100
Reference numeral 1 denotes a background color (white) and an image portion of a black-and-white image document. Pixels are distributed at a saturation of 0, and there are no accumulated pixels in a region having a high saturation S (color image region). On the other hand, the accumulated pixels 1002 shown on the lower side represent the background color (white) and the achromatic image portion of the color image document, and the accumulated pixels 1003 of the color image portion are distributed.

As an example of a method for judging these differences, a method for judging whether or not the accumulated pixels N are equal to or larger than a certain threshold value (N ≧ Th) in the color image area (S ≧ Sth) in the histogram. Can be considered. In the embodiment of the second invention, the color image area (S ≧ St
h), if there are accumulated pixels of a certain threshold ≧ (N ≧ Th) (1003), the image document is determined to be a color image document, and a certain threshold ≧ (N ≧ Th) in the color image area (S ≧ Sth).
A case where there is no accumulated pixel of Th) is determined to be a black and white image original.

The result of the judgment made by the original image color judgment means 90 is input to the first color space conversion means 102. The first color space conversion means 102 forcibly outputs Ca = Cb = 0 and outputs the three-color separation signals R1, G
1, NB1 is converted to a complete achromatic signal. After that,
As described in the first embodiment, edge enhancement is performed only on the brightness signal L for an achromatic image.
However, in the embodiment of the second invention, the color difference signal is Ca = Cb = 0 even after the edge enhancement. Further, luminance / density conversion, color correction processing, binarization, smoothing / resolution conversion, and the like are performed, and a monochrome image is output from a color image output unit 109 composed of an electrophotographic printer or the like, thereby completing black and white copying.

On the other hand, if the result of the determination by the document image color determining means 90 is a color image document, the same processing as in the above-described first embodiment of the present invention is performed. As described above, according to the embodiment of the second invention, the same operation and effect as those of the above-described embodiment of the first invention can be achieved. Is determined in advance as a color document or a black-and-white document, the color difference signal can be set to Ca = Cb = 0 even after edge enhancement for the black-and-white image, and the chromaticity component can be reliably removed, thereby deteriorating the image quality. In addition to this, it is possible to reduce the cost load related to edge enhancement, and to improve image quality such that monochrome signals can be converted to achromatic signals without excessive or insufficient image density.

When the result of the determination is a black and white image original, the output of the color correction means 107 is C ₂ = M ₂ = Y ₂ =
It may be set to 0.

(Embodiment of Third Embodiment) Hereinafter, FIG.
An embodiment of the third invention according to the present invention will be described in detail with reference to FIG. In FIG. 11, the same configuration as that of the embodiment of the first embodiment shown in FIG. 1 described above is denoted by the same reference numeral, and detailed description is omitted. The third embodiment differs from the first embodiment shown in FIG.
1 in that a color mode designating unit 1101 is further provided in the configuration of FIG. The color mode designating unit 110 has a key input unit that allows an operator to perform an operation input, and outputs the image output by the color image output unit 110 from the key switch unit in a full color mode or in a monochrome (mono color) mode. It is configured to be able to specify whether to output.

The following description is about whether to output a full-color copy image or a mono-color output (including black and white) when performing color image processing in the color copying machine according to the third embodiment of the present invention. An example of the designation and the related image processing will be described. In the third embodiment of the present invention, when a copy original image is output in mono-color, an output color is designated by the color mode designation means 1101 prior to the copy operation. More specifically, full color / mono color designation switching and mono color hue designation are performed using the key input unit of the color mode designation means 1101.

When a mono color and a hue are designated by the color mode designation means 1101, a mono color designation signal is outputted and inputted to the first color space conversion means 102. Further, the hue designation signal is also supplied to the color mode designation means 1.
The signal is output from the image processing unit 101 and input to the color correction unit 107.
When the mono-color designation signal is input to the first color space conversion means 102, the first color space conversion means 102 sets the chromaticity signal of the input three-color separation signal of the original image to Ca = Cb = 0. Convert to an achromatic signal. As a result, the color original image is first converted into a black-and-white original image (achromatic image) having only brightness gradation.

Hereinafter, similarly to the above-described first embodiment, edge enhancement is performed only on the brightness signal L, and density signals C1, M1, and Y1 are generated by the brightness / density conversion 106 (C1 = M1). = Y1). Next, when the hue designation signal is input to the color correction means 107, the color correction means 107 performs color correction for reproducing the designated color. For example, if the hue is designated as cyan, the color correction means 107 outputs a signal of only cyan C2 (M2 = Y2 = K2 = 0), and if the hue is designated as red (a mixed color of magenta and yellow), 107 outputs a signal of only magenta M2 and yellow Y2 (C2 = K2 = 0).

The mono-color signal generated as described above is subjected to binarization, smoothing / resolution conversion and the like in the same manner as in the first and second embodiments, and is constituted by an electrophotographic printer or the like. A monochrome image is printed and recorded from the color image output unit 110. As described above, the third embodiment of the present invention can achieve the same operation and effect as those of the second embodiment of the present invention, and can further specify a mono-color hue, thereby accurately obtaining a desired hue. Image output is possible.

(Other Embodiments of the Invention) The present invention can be applied to a system composed of a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), and a single device can be used. (For example, a copying machine, a facsimile machine, etc.). Further, an object of the present invention is to supply a storage medium storing a program code of software for realizing the functions of the above-described embodiments to a system or an apparatus, and to execute a computer (or CPU or MP
It goes without saying that U) can also be achieved by reading and executing the program code stored in the storage medium.

In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention. Examples of a storage medium for supplying the program code include a floppy disk, hard disk, optical disk, magneto-optical disk, and C
A D-ROM, a CD-R, a magnetic tape, a nonvolatile memory card, a ROM, and the like can be used.

When the computer executes the readout program code, not only the functions of the above-described embodiment are realized, but also the OS (Operating System) running on the computer based on the instruction of the program code. ) May perform some or all of the actual processing, and the processing may realize the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, based on the instruction of the program code, It goes without saying that the CPU included in the function expansion board or the function expansion unit performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

Further, in the above-described example, the explanation has been made using the edge enhancement as an example of the correction of the spatial frequency characteristic. However, the same concept can be applied to the smoothing. Further, in the above example, the spatial filter coefficient is controlled according to the character / image determination result. However, for example, the control may be performed according to the character / image / halftone dot determination result.

As described above, according to the embodiment of the present invention, it is possible to greatly reduce the necessary circuit configuration such as a required line memory or a multiplier or an adder in the edge enhancement correction as compared with the related art. it can. Further, by performing image processing using the delayed color difference signal by the delay means, spatial image processing can be realized on the chromaticity signal without newly providing a delay circuit, and the target pixel is determined to be achromatic. In this case, the chromaticity component is corrected for the chromaticity signal to reduce the cost load associated with edge enhancement without deteriorating the image quality. The image quality can be improved, for example, black color can be converted to black.

[0080]

As described above, according to the present invention, it is possible to correct spatial frequency characteristics such as edge enhancement while suppressing image quality deterioration, and to reduce the cost burden associated with the correction. An image processing apparatus and method capable of performing the above-described operations can be provided. Further, it is possible to provide a color image processing apparatus and method capable of converting an achromatic signal into a single black color without excessive or insufficient image density.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an image processing apparatus according to an example of an embodiment of the present invention;

FIG. 2 is a diagram illustrating an example of a spatial filter coefficient used in the embodiment of the present invention.

FIG. 3 is a diagram illustrating an example of a signal delay unit according to the embodiment of the present invention.

FIG. 4 is a flowchart illustrating an edge enhancement correction amount generation process for an edge enhancement amount distribution brightness signal according to the embodiment of the present invention.

FIG. 5 is a schematic diagram illustrating an edge enhancement correction amount for a brightness signal of an edge enhancement amount distribution according to the embodiment of the present invention.

FIG. 6 is a flowchart illustrating generation of an edge enhancement correction amount for a chromaticity signal in edge enhancement amount distribution according to the embodiment of the present invention.

FIG. 7 is a schematic diagram illustrating an edge enhancement correction amount for a chromaticity signal in an edge enhancement amount distribution according to the embodiment of the present invention.

FIG. 8 is a schematic diagram illustrating the preservation of color (hue) with respect to edge enhancement of a chromaticity signal in the embodiment of the present invention.

FIG. 9 is a block diagram illustrating a configuration of an image processing apparatus according to a second embodiment of the present invention.

FIG. 10 is a schematic diagram of a histogram of a saturation signal for explaining a document image color determination process in the embodiment of the second invention.

FIG. 11 is a block diagram illustrating a configuration of an image processing apparatus according to a third embodiment of the present invention.

FIG. 12 is a block diagram illustrating a configuration of a conventional image processing apparatus.

FIG. 13 is a diagram illustrating spatial filter coefficients of a conventional image processing apparatus.

FIG. 14 is a diagram showing a spatial filter processing circuit of a conventional image processing apparatus.

[Explanation of symbols]

 Reference Signs List 101 color image input means 102 first color space conversion means 103 delay means 104 edge enhancement means 105 second color space conversion means 106 brightness / density conversion means 107 color correction means 108 binarization means 109 smoothing / resolution conversion means 110 color Image output unit 111 Character / image determination unit 112 Spatial filter coefficient storage unit 113 Edge enhancement amount extraction unit 114 Saturation amount extraction unit 115 Achromatic / chromatic color determination unit 116 Edge enhancement amount distribution unit 117 Black character / color character / image determination unit 201 Character spatial filter coefficient 202 Image spatial filter coefficient 701 Target pixel chromaticity vector 702 Target pixel chromaticity signal Ca1 703 Target pixel chromaticity signal Cb1 704 Target pixel chromaticity vector after edge enhancement 705 Target pixel chromaticity signal after edge enhancement 706 Target after edge enhancement Pixel chromaticity signal Cb2 801 to 806 Line memory 901 Original image color determining means 1001 Black and white image original cumulative pixels 1002 Color image original achromatic cumulative pixels 1003 Color image original color cumulative pixels 1101 Color mode specifying means 1201 Achromatic / chromatic color determining means 1301 Character spatial filter coefficient 1302 Image spatial filter coefficient 1401 Edge enhancement means data delay section 1402 Edge enhancement means spatial filtering operation section 1404 to 1428 Multipliers 1429 to 1452 Adders

Claims (36)

[Claims] 1. An image processing apparatus for performing sharpness correction on an input image signal, comprising: an extraction unit configured to extract a chrominance signal from the input image signal from a lightness signal; and an edge amount based on the lightness signal. Edge amount extraction means for extracting a color component, a saturation extraction means for extracting a saturation component based on the chromaticity signal, and an edge amount extraction means for extracting the saturation component based on the saturation component extracted by the saturation extraction means. Distributing means for distributing an enhancement amount of an edge portion based on the obtained edge amount to the brightness signal and the chromaticity signal; and correcting the brightness signal and the chromaticity signal with the enhancement amount of the edge portion distributed by the distribution device. An image processing apparatus comprising: edge enhancement means. 2. An image processing apparatus according to claim 1, wherein said input image signal is an RGB signal, and further comprising a conversion unit for converting an enhanced brightness signal and a chromaticity signal by said edge enhancement unit into an RGB signal. Image processing device. 3. The distribution unit according to claim 1, wherein the distribution ratio for the chromaticity correction is higher than that for the lightness correction when the chroma component is large, and the distribution ratio for the lightness correction is color when the chroma component is small. The image processing apparatus according to claim 1, wherein the image data is distributed so as to be higher than that for the degree correction. 4. The image processing apparatus according to claim 1, wherein the extraction unit converts the input image signal into a brightness signal and a chromaticity signal including two components. 5. The image processing apparatus according to claim 1, further comprising an achromatic / chromatic color determining unit that determines whether the input image signal is a chromatic color or an achromatic color based on a chroma component extracted by the chroma extracting unit. Item 5. The image processing device according to any one of Items 4. 6. The apparatus according to claim 1, further comprising delay means for delaying said lightness signal by N lines and delaying said chromaticity signal by N / 2 lines. 6. The image processing apparatus according to any one of 5. 7. The chromaticity extracting means according to claim 1, wherein said chromaticity signal delayed by N / 2 lines by said delaying means is N / 2 + 1.
7. The image processing apparatus according to claim 6, wherein a spatial filtering process of the line is performed. 8. The achromatic / chromatic color judging unit judges whether the chromaticity signal delayed by N / 2 lines by the delay unit is N
7. The image processing apparatus according to claim 6, wherein a spatial filtering process of / 2 + 1 line is performed. 9. The distribution unit changes a distribution ratio of an image edge amount according to a saturation component of the saturation extraction unit and a determination result determined by the achromatic / chromatic color determination unit. The image processing device according to claim 5. 10. The edge emphasizing means, when the image is determined to be achromatic by the achromatic / chromatic color determining means,
10. The image processing apparatus according to claim 5, wherein a correction for removing a chromaticity component is performed on the chromaticity signal. 11. An image processing method for performing sharpness correction on an input image signal, comprising: an extraction step of extracting a chromaticity signal from a brightness signal from the input image signal; and an edge amount based on the brightness signal. An edge amount extraction step of extracting a color component, a saturation extraction step of extracting a saturation component based on the chromaticity signal, and an edge amount extraction step extracted in accordance with the saturation component extracted in the saturation extraction step. Distributing the enhancement amount of the edge portion based on the edge amount to the lightness signal and the chromaticity signal; and correcting the brightness signal and the chromaticity signal with the enhancement amount of the edge portion distributed in the distribution step. An image processing method comprising: an edge enhancement step. 12. The apparatus according to claim 11, wherein the input image signal is an RGB signal, and further comprising a conversion step of converting an enhanced brightness signal and a chromaticity signal in the edge enhancement step into an RGB signal. Image processing method. 13. The distribution step, wherein when the chroma component is large, the distribution ratio for chromaticity correction is higher than that for lightness correction, and when the chroma component is small, the distribution ratio for lightness correction is 13. The image processing method according to claim 11, wherein the distribution is performed so as to be higher than that for the degree correction. 14. The image processing method according to claim 11, wherein the extracting step converts the input image signal into a brightness signal and a chromaticity signal including two components. 15. An achromatic / chromatic color determining step for determining whether the input image signal is a chromatic color or an achromatic color based on a chroma component extracted in the chroma extracting process. Item 15. The image processing method according to any one of Items 14. 16. The apparatus according to claim 11, further comprising a delay step of delaying said lightness signal by N lines and delaying said chromaticity signal by N / 2 lines. 16. The image processing method according to any one of the above items 15. 17. The method according to claim 17, wherein the chroma extracting step comprises: N / 2 +
17. The image processing method according to claim 16, wherein spatial filtering of one line is performed. 18. The method according to claim 16, wherein the achromatic / chromatic color determination step performs a spatial filtering process of N / 2 + 1 lines on the chromaticity signal delayed by N / 2 lines by the delay step. Image processing method. 19. The distribution step changes a distribution ratio of an image edge amount according to a saturation component in the saturation extraction step and a determination result determined in the achromatic / chromatic color determination step. An image processing method according to any one of claims 16 to 18. 20. The edge emphasizing step, wherein when the image is determined to be achromatic by the achromatic / chromatic color determining step,
20. The image processing method according to claim 16, wherein the chromaticity signal is corrected to remove a chromaticity component. 21. A generating means for generating a brightness signal and a chromaticity signal, an extracting means for extracting a signal corresponding to a spatial frequency characteristic based on the brightness signal, and the brightness signal based on a signal extracted by the extracting means. And an control unit for controlling a spatial frequency characteristic of the chromaticity signal. 22. A signal according to the spatial frequency characteristic,
22. The image processing apparatus according to claim 21, wherein the signal is a signal representing an edge amount of an image. 23. The image processing apparatus according to claim 21, wherein the control unit controls edge enhancement of the lightness signal and the chromaticity signal. 24. A generating step for generating a brightness signal and a chromaticity signal, an extracting step for extracting a signal corresponding to a spatial frequency characteristic based on the brightness signal, and the brightness signal based on a signal extracted by the extracting means. And a control step of controlling a spatial frequency characteristic of the chromaticity signal. 25. A signal according to the spatial frequency characteristic,
The image processing method according to claim 24, wherein the signal is a signal representing an edge amount of the image. 26. The image processing method according to claim 24, wherein said control step controls edge enhancement of said lightness signal and said chromaticity signal. 27. A generating means for generating a lightness signal and a chromaticity signal, a first extracting means for extracting an edge amount based on the lightness signal, and a second extracting means for extracting a chroma component based on the chromaticity signal. Extraction means; and control means for controlling a spatial frequency characteristic of the lightness signal or the chromaticity signal based on the edge amount and the saturation amount respectively extracted by the first and second extraction means. Image processing device. 28. The image processing apparatus according to claim 27, wherein said control means controls edge enhancement of said lightness signal or said chromaticity signal. 29. The image processing apparatus according to claim 29, further comprising: a determination unit that performs achromatic / chromatic color determination based on the saturation amount extracted by the second extraction unit. The image processing apparatus according to claim 27, wherein the characteristic is controlled. 30. A generating step of generating a lightness signal and a chromaticity signal, a first extracting step of extracting an edge amount based on the lightness signal, and a second extracting step of extracting a chroma component based on the chromaticity signal. An extraction step; and a control step of controlling a spatial frequency characteristic of the lightness signal or the chromaticity signal based on the edge amount and the saturation amount extracted in the first and second extraction steps, respectively. Image processing method. 31. The image processing method according to claim 30, wherein the control step controls edge enhancement of the lightness signal or the chromaticity signal. 32. A determination step for performing achromatic / chromatic color determination based on the saturation amount extracted in the second extraction step, wherein the control step includes: The image processing method according to claim 30, wherein characteristics are controlled. 33. Generating means for generating a lightness signal and a chromaticity signal, delay means capable of delaying the lightness signal by N lines and delaying the chromaticity signal by N lines, and N lines by the delaying means. Extracting means for extracting an edge amount by using the brightness signal delayed by the minute, and spatial frequency of a chromaticity signal delayed by (N / 2) lines by the delay means according to the edge amount extracted by the extracting means An image processing apparatus comprising: control means for controlling characteristics. 34. A generator for generating a lightness signal and a chromaticity signal, and a correction unit for performing a correction process of a spatial frequency characteristic on the chromaticity signal, wherein the correction unit includes the lightness signal and the color. An image processing apparatus that performs a correction process so that a hue of an image represented by a degree signal is stored before and after the correction process. 35. A generating step of generating a lightness signal and a chromaticity signal, and a correcting step of performing a correction process of a spatial frequency characteristic on the chromaticity signal, wherein the correcting step includes the lightness signal and the color. An image processing method, wherein a correction process is performed such that a hue of an image represented by a degree signal is stored before and after the correction process. 36. A reading means for scanning an original and generating an image signal representing the original, and whether the original is a color original based on an image signal obtained by the first scanning of the original by the reading means. Determining means for determining whether the document is a black-and-white document; converting an image signal obtained by a first scan of the document by the reading means into a brightness signal and a chromaticity signal; Processing means for fixing the degree signal to a predetermined value.