JPH1042151A - Image processing apparatus and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To discriminate an achromatic/chromatic color of each picture element in received color image data with high accuracy. SOLUTION: In the case of receiving data L (luminance signal representing brightness) and Ca, Cb (chroma signal representing color), smoothing means 31, 32 receive the Ca, Cb components in the unit of 3×3 areas and calculate weight mean of them and provide output to a saturation extract means 33. The saturation extract means 33 obtains a distance from an axis denoting an achromatic color based on the weight mean Ca, Cb and provides an output of the result to an achromatic/chromatic color discrimination means 34. The achromatic/chromatic color discrimination means 34 compares the received value with a threshold value so as to discriminate whether the picture element position depicts an achromatic color or a chromatic color and provides an output of the result as a signal KC.

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 determining saturation based on input image data.

[0002]

2. Description of the Related Art A color copying machine is generally known as a device for inputting color image data and printing the input image at a predetermined printing unit.

According to the recent image processing technology, it has become possible to perform processing suitable for a character / line image in a document and a gradation image such as a photograph. What is important is how to accurately identify a character line image, a gradation image, and a color image in the same document. If the accuracy of this technique is not good, the edges will be unclear and may cause color misregistration even though they should originally be recognized as character line drawings, resulting in poor output quality.

[0004]

As described above, the color judgment is performed on a pixel-by-pixel basis. However, the problem here is that the original color image data may be affected by noise or the like at the time of reading by the image scanner unit. Affected, and incorrect color decisions are made.

In addition, a specific color is likely to be erroneously determined to be an achromatic color, and a high color density is likely to be erroneously determined to be an achromatic color.

Furthermore, even when an achromatic color is read by a scanner, mechanical vibration, lens chromatic aberration, MTF
There is also a problem that a color misregistration occurs due to a difference between the chromatic colors and an erroneous determination is made as a chromatic color.

[0007] As a result of the erroneous determination regarding the achromatic color / chromatic color, the subsequent color correction means and the edge emphasis processing are affected, so that the finally formed image quality is deteriorated.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has been made in consideration of the above-described problems, and has been made in view of the above circumstances. It is an object to provide a processing apparatus and a method thereof.

In order to solve this problem, for example, an image processing apparatus of the present invention has the following configuration. That is,
An image processing apparatus that determines an attribute of each pixel based on color image data of a color space represented by a lightness signal and a chromaticity signal, and an input unit that inputs the chromaticity signal in a predetermined area unit. Computing means for calculating the saturation amount based on the chromaticity signal in the predetermined area, and determining means for determining whether the pixel of interest is achromatic or chromatic based on the saturation amount obtained by the calculation.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

The input three-color separation signal R1,
When G1 and B1 are set, a lightness signal L1 representing the brightness,
And a chromaticity signal (Ca1, Cb1) representing the tint (a color space other than this, for example, L * a * b *, L * u * v *, etc. may be used).

Equation (1) shows an example of a conversion equation for simply converting the three-color separation signals R, G, and B into lightness and chromaticity signals L1, Ca1, and Cb1.

L = (R + 2 × G + B) / 4 Ca = (R−G) / 2 Cb = (R + G−2 × B) / 4 Equation (1) In the determination of achromatic / chromatic colors, the lightness signal L1 It is conceivable that the saturation S is first determined by the following equation (2) using the values of each of Ca1 and Cb1 synchronized with the center pixel of. That is, S (= (Ca1 ^ 2 + Cb1 ^ 2) ^ 0.5) Equation (2) Then, using the predetermined threshold value ρ, the above equation (3)
Is determined according to That is, (when S <ρ) KC = achromatic color (when ρ ≦ S) KC = chromatic color Expression (3)

However, if the determination is made one pixel at a time as described above, accurate signals such as a case where noise is included in a signal input from the scanner unit and a case where color shift occurs due to the influence of vibration of the scanner, etc. Color judgment cannot be performed.

Therefore, in the present embodiment, a memory for data delay is used, the values of a plurality of pixels are integrated and used for determination, thereby reducing the influence of noise and color shift, and performing color determination with higher accuracy. Do.

FIG. 1 is a block diagram showing the main components of image processing in the embodiment, and FIG. 2 is a diagram showing a delay means 103B in FIG.
2 shows a specific block diagram of FIG.

Reference numeral 101 denotes color image input means for inputting a document as color data, and is a document image reading device such as a color image scanner. However, the present invention is not limited to this, and includes an image input unit from a computer in a broad sense. Therefore, a device for inputting an image stored in a storage medium such as a magneto-optical disk is also included. The color image input means 101 outputs three color separation signals R1, G1, and B1 which are separated into RGB for each pixel of the color image.

A G1 signal (a value closest to the luminance signal among the three components) 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 a character. / The image is input to the image determination unit 111, and the pixel is a line image such as a character or a thin line, or a continuous tone image (or a halftone image) such as a photographic image or a print image
And outputs a character / image determination signal TI. The spatial filter coefficient storage unit 112 receives the character / image determination signal TI, and stores the character spatial filter coefficient 201 shown in FIG. 16 when the corresponding pixel is a character signal and the same when the corresponding pixel is a gradation image. The image spatial filter coefficient 202 shown in the figure is selected, and the character or image spatial filter coefficient Kij is output to the edge enhancement good extraction means 113.

On the other hand, the input three-color separation signals R1, G1, B1 of the color image are supplied to a first color space conversion means 102, where, for example, lightness signals L1,
And a chromaticity signal (Ca1, Cb1) representing the tint (note that other color spaces, for example, L * a * b *)
Or L * u * v *, etc., as described above.

The lightness signal L1 and the chromaticity signals (Ca1, Cb1) output from the first color space conversion means 102 are
By the line memories 21 to 24 of the delay unit 103B,
4 lines for the brightness signal L1, line memories 25 and 26
Thus, in order to synchronize with the central pixel of the brightness signal, two lines for the chromaticity signal Ca1 and two lines for the chromaticity signal Cb1 are stored by the line memories 25 and 26. Now, assuming that the center line is the j line, the j-2, j-1, j, j + 1 lines are stored for the lightness, so that the lightness signals for five lines including the current line j + 2 are output. become.

On the other hand, for the chromaticity signal Ca1, the line memories 25 and 26 of the delay means 103B j, j +
One line is stored, and chromaticity signals Ca1 for three lines including the current line j + 2 are output. Similarly, for the chromaticity signal Cb1, the j and j + 1 lines are stored and the chromaticity signal Cb1 for three lines including the current line j + 2 is stored.
Is output.

In this embodiment, when calculating the saturation signal S and the achromatic / chromatic color determination signal KC, j, j + 1, j +
Spatial processing is performed using data for two lines and three lines.

FIG. 3 shows the color judgment means 120 in the embodiment.
FIG. In FIG.
Reference numeral 32 denotes a 3 × 3 size integrating means, which performs a weighted average calculation in accordance with a preset coefficient to obtain an average value Ca of the pixel of interest.
1_SM and Cb1_SM are output.

FIG. 4 shows an example of coefficients when the weighted average calculation is performed. That is, according to the illustrated counts, Ca1_SM and Cb1_SM at the target pixel position are calculated as literally average values.

Reference numeral 33 denotes a saturation determining means which determines the saturation S from the weighted averaged values of Ca1_SM and Cb1_SM, and outputs it to the edge enhancement amount distribution means 116. In the present embodiment, as described above, the calculation is performed as Sj + 1 = (Ca1_SM ^ 2 + Cb1_SM ^ 2) ^ 0.5.

Here, Sj + 1 is delayed by one line in the line memory, and the saturation amount Sj for the j line is output.

Numeral 34 denotes an achromatic / chromatic color judging means, which inputs the value of S, judges achromatic / chromatic color using a predetermined threshold value ρ according to the following equation, and executes an achromatic / chromatic color judgment signal. Outputs KC.

(When S <ρ) KC = achromatic color (when ρ ≦ S) KC = chromatic color The edge enhancement amount distribution means 116 includes an edge enhancement amount ε, a saturation signal S, and an achromatic / chromatic color determination signal. KC is input, an edge enhancement correction amount εl of the brightness signal L1 and an edge enhancement correction amount εc of the chromaticity signals (Ca1, Cb1) are generated and supplied to the edge enhancement means 104 in accordance with those values.

Edge emphasis correction amount ε for brightness signal L1
l will be described. Basically, the lower the value of the saturation signal S (closer to achromatic color), the more the edge enhancement amount ε with respect to the brightness signal
Is increased, and the entire edge enhancement amount ε is assigned to εl for an achromatic signal pixel (KC = 0).

The edge enhancement correction amount εc for the chromaticity signals (Ca1, Cb1) will be described. Contrary to that of the lightness signal, the higher the value of the chroma signal S (brighter color), the more the distribution of the edge enhancement amount ε to the chromaticity signal is increased. Edge correction is not performed on the signal pixel (KC = 0), and the chromaticity signal of the target pixel is also removed. This is because, in the case of an image processing apparatus in a color copying machine or the like, the fact that color components remain in a copied image such as a black character is visually very poor in image quality. Therefore, it is necessary to cut color components for such pixels and perform color correction to complete achromatic signals.

The edge enhancement correction amounts εl and εc generated as described above are supplied to the edge enhancement means 104 together with the L, Ca and Cb signals. Here, the edge enhancement correction amount ε1 is added to the lightness signal L, and the chromaticity signals Ca, Cb
Is multiplied by the edge enhancement correction amount εc (Equation 4).

L2 = ε1 + L1 Ca2 = εc * Ca1 Cb2 = εc * Cb1 Equation (4) As can be seen from equation (4), the saturation is increased by adding the edge correction amount ε1 to the signal L. For pixels for which edge edge enhancement is not desired for brightness (εl = 0), brightness is preserved.

On the other hand, by multiplying the signals Ca and Cb by the edge correction amount εc, by multiplying εc = 0 for a pixel having low chroma and judged to be an achromatic color,
The chromaticity component of the target pixel itself is removed.

As described above, the edge enhancement means 104
, Ca2, C with edge enhancement
b2 is output to the second color space conversion means 105, and
It is converted back to a GB signal.

Equation (5) is the lightness and chromaticity signals L2, Ca
2, Cb2 is an example of a conversion equation for converting into three-color separation signals R2, G2, B2, and is an inverse conversion of equation (1) shown above.

R = (4 × L + 5 × Ca + 2 × Cb) / 4 G = (4 × L−3 × Ca + 2 × Cb) / 4 B = (4 × L + Ca−6 × Cb) / 4 Equation (5) RGB The three-color separation signal, which has been inversely converted into a signal, is supplied to the luminance / density conversion means 106, where the three-color separation signal R2,
The density signals C1,
Convert to M1, 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 color correction means 107.
K2 is output. Further, the color correction means 107 determines the determination signal KC which is a determination result of the achromatic / chromatic color determination means 115.
When the target pixel is achromatic, the density signals C2 and M
2, Y2 is set to C2 = M2 = Y2 = 0, and converted to a pixel consisting of a single black color.

Reference numeral 110 denotes a color image output means, 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 images C3, M3, Y3 and K3. There are various binarization methods such as an error diffusion method and a dither method, and the binarization process is performed by a method suitable for each device.

When the resolution of the image input from the color image input means 101 and the resolution of the image output by the color image output means 110 are different, the binary image C
3, M3, Y3 and K3 are smoothing / resolution conversion means 109
C4, M4, Y4, K
4 is converted. 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.
The image is printed and recorded by the color image output unit 110.

By performing the color judgment by the above-described method, the noise component generated sporadically becomes less likely to affect the color judgment by integration. In addition, since the chromatic color components around the black characters generated by the color misregistration can also be subjected to the integration processing with the white background and the black characters of the black characters, the saturation decreases and it can be determined that the color is achromatic.

As a result, the influence of noise and color shift can be suppressed, and more accurate color judgment can be performed.

The output signal TI from the character / image determining means 111 is input to the color correcting means 107, and only when KC is achromatic and it is indicated that TI is a character image by a signal, the corresponding By controlling the output of the pixel to be K monochromatic, only the achromatic character pixel can be output in K monochromatic.

Further, in areas other than the character pixels, normal color correction processing is performed, and natural color reproduction is performed in the continuous tone portion by performing color reproduction using CMYK color mixture.

<Second Embodiment> In the above embodiment, the values of each of Ca1 and Cb1 synchronized with the central pixel of the brightness signal L1 are used, and the saturation S, That is, S = (Ca1 ^ 2 + Cb1 ^ 2) ^ 0.5 is calculated, and using a predetermined threshold value ρ, (when S <ρ) KC = achromatic color (when ρ ≦ S) KC = chromatic color The judgment was made as the equation (6).

However, when the determination is made in this way, since the determination slice for achromatic / chromatic colors is not changed depending on the color, colors that are likely to cause erroneous determination (actually blue and green) and colors that are unlikely to occur are determined. And the slice cannot be distinguished. Therefore, if a slice is matched with a color that is unlikely to cause erroneous determination, erroneous determination occurs in blue or green, resulting in an achromatic color. In addition, if a slice is matched with a color that is likely to cause an erroneous determination, an erroneous determination occurs in a black or gray portion or a color misregistration portion, and a chromatic color is determined.

In addition, since saturation is not so much obtained for a color having a high density, at the same slice level as that for a light color,
A chromatic color is easily misjudged as an achromatic color.

In the second embodiment, the saturation extracting means includes:
The achromatic color / chromatic color determining means is combined and the color determining means 13
0 (see FIG. 5), and the color determination means 130
1, Cb1 as input values, and achromatic /
By changing the chromatic color determination slice, more accurate color determination is performed, and the saturation signal S and the achromatic / chromatic color determination signal KC are output.

Hereinafter, the second embodiment will be described in detail with reference to FIGS. FIG. 5 is a block diagram of a main part of the apparatus, and FIG. 6 shows a specific block structure of the color determination means 130. Also, means having the same numbers as in FIG. 1 have the same function, and a description thereof will be omitted.

In FIG. 6, reference numeral 61 denotes a lightness judging means for which the value of L1 is a predetermined threshold value sl_L1, sl
The lightness determination signal JL is output based on whether it is within the range set by _L2. That is, JL = 0 when sl_L1 <L <sl_L2 JL = 1 in other cases JL = 1 ... Equation (7) In other words, JL = 1, JL = 0 within the range.

The value of the lightness determination signal JL is used to adjust a threshold value which is used as a criterion for achromatic / chromatic color described later. In the above equation (7), the high lightness (J
L = 1), medium (JL = 0), and low (JL = 1), but in order to increase the accuracy,
The determination may be made in multiple stages. This is because, when the orthogonal axes in the two-dimensional plane are Ca and Cb and the orthogonal axis perpendicular to the plane is L, the space represented by L, Ca, and Cb is represented as a distorted sphere.

Reference numeral 62 denotes a saturation amount extracting means, which includes Ca1, Cb1
Is determined from the value of, and output to the edge enhancement amount distribution means. In the second embodiment, it is assumed that S = (Ca1 ^ 2 + Cb1 ^ 2) ^ 0.5 as described above.

Reference numeral 63 denotes achromatic / chromatic color judging means.
The values of Ca and Cb are input, and the setting of the achromatic / chromatic color determination threshold is changed according to the values.

In the second embodiment, the range of the determination is changed depending on the difference in brightness when the determination of the color of blue or green is strict.

Simulatedly, when the determination of blue or green color is strict, the achromatic / chromatic color determining means 6 is used.
In 3, the result of the brightness determination means 61 is not used.

In the Ca and Cb color space, the components of Ca and Cb having blue and green colors correspond to the hatched portions in FIG. 7A. Therefore, by setting the following conditions, the determination as blue or green can be made strict.

If Ca1 ≧ 0 OR Cb1 ≧ 0, sl_S = m If Ca1 <0 AND Cb1 <0, sl_S = n Expression (8) (where m> n) Further, the saturation signal S (S = (Ca1 ^ 2 + Cb1 ^ 2) ^ 0.5)
Equation (3) is changed as shown in the following equation (9).

(When S <sl_S) KC = achromatic color (when sl_S ≦ S) KC = chromatic color Expression (9) By doing so, the determination of achromatic / chromatic color is performed as shown in FIG.
Since the determination space is as shown in FIG. 3B (the shaded portion is determined to be achromatic), the determination can be made strict as blue or green.

In the case where the range of determination is changed depending on the difference in brightness, the following is performed.

In the L, Ca, Cb space, as the value of L changes from the lowest state to the higher direction, the possible range of Ca, Cb gradually increases, and after a certain position, gradually decreases. . This can be understood from the fact that the sphere is distorted as described above.

In such an empty space, if the slice for the saturation S is always constant regardless of the value of L,
When the value of L is somewhat small or more than a certain value, the values that can be taken by Ca and Cb originally become small, so that the slice level no longer exceeds or rarely exceeds the slice level. In other words, the possibility of erroneously determining an achromatic color unconditionally increases.

Therefore, in the second embodiment, by changing the determination color space of Ca and Cb using the above-described saturation determination signal JL of L, a portion having a small lightness and / or a large brightness. This is to prevent erroneous determination at a part.

In order to achieve the object of the second embodiment, as shown in FIGS. 8A and 8B, when the lightness L is small (or large), the judgment area is small, and the lightness L is within the range. If it is within the range, the slice is changed so as to enlarge the determination area.

As described above, JL = 0 when the threshold value sl_L1 <lightness L <threshold value sl_L2, and JL = 1 when the lightness is small and large.

Then, when JL = 0, sl_S = m, when JL = 1, sl_S = n (where m> n) (when S <sl_S) KC = achromatic (when sl_s ≦ S) KC = Chromatic color Expression (10) By doing so, a decision space as shown in FIGS. 8A and 8B is obtained, so that it is possible to prevent erroneous determination of achromatic color / chromatic color in a portion with low brightness. .

In the second embodiment, the change in the color space for determination of Ca and Cb and the change in the color space of Ca and Cb with respect to L are separately shown. ,
Since Ca and Cb are respectively input, it is also possible to create a determination color space by combining both. In addition, this makes it possible to perform more accurate color determination.

<Third Embodiment> Next, a third embodiment will be described. As described above, the achromatic / chromatic color determination is uniformly performed for each pixel by the equation (2) according to the equation (2).
Saturation S (= (Ca1 ^ 2 + Cb) obtained using the value of b1
1 ^ 2) ^ 0.5), using a predetermined threshold value ρ, the above equation (3), that is, (when S <ρ) KC = achromatic color (when ρ ≦ S) KC = chromatic color If the determination is made, accurate color determination cannot be performed, for example, when an input image is input from a scanner or the like, when noise is included in the signal, or when color shift occurs due to the influence of scanner vibration or the like.

Therefore, in the third embodiment, the effect of noise and color misalignment is reduced by integrating the values of a plurality of pixels using the memory for data delay and using the integrated values for determination, thereby providing more accurate data. Perform color determination. This makes it possible to suppress the influence of noise and color misalignment, and to perform more accurate color determination. However, on the other hand, when an original written with black characters on a chromatic background is input, the characteristics of the L, Ca, and Cb components of the black characters are changed to L, Ca , And Cb components, the colors may be canceled out, and may not be accurately determined as an achromatic color, which may cause an erroneous determination. As a result, a problem that the reproduction of black characters in the chromatic color deteriorates may occur.

Further, in the third embodiment, more accurate color judgment can be performed by using both the color judgment result for each pixel and the color judgment result obtained by performing weighted integration. I do.

Hereinafter, a third embodiment according to the present invention will be described in detail with reference to FIG. Note that means having the same numbers as in FIG. 1 have the same function, and a description thereof will be omitted. Therefore, only the points different from FIG. 1 will be described below.

In the third embodiment, the saturation extracting means and the achromatic / chromatic color judging means are collectively referred to as a color judging means 140 as shown in FIG. Color determination means 140
Is input values of Ca1, Cb1, and L1 for three lines,
It is assumed that a saturation signal S and an achromatic / chromatic color determination signal KC for the determination target pixel are output.

Referring to FIG. 10, the delay means 103 of the present invention will be described.
C will be described. The lightness signal L1 and the chromaticity signals Ca1, Cb1 output from the first color space conversion means 102
Are four lines for the lightness signal L1 by the line memories 11 to 14 of the delay unit 103C,
16 to synchronize with the center pixel of the brightness signal,
Two lines for the chromaticity signal Ca1 and the line memories 15 and 1
6, 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 as a result, the lightness signals of five lines including the current line j + 2 are obtained. Is output.

On the other hand, for the chromaticity signal Ca1, j, j +
One line is stored, and chromaticity signals Ca1 for three lines including the current line j + 2 are output. Similarly, for the chromaticity signal Cb1, the j and j + 1 lines are stored and the chromaticity signal Cb1 for three lines including the current line j + 2 is stored.
Is output.

In the third embodiment, when calculating the saturation signal S and the achromatic / chromatic color determination signal KC, j + 2, j
Data L1, Ca1, Cb for three lines of +1 and j lines
1, spatial processing is performed with the pixel of interest as the j + 1 line.

FIG. 11 is a block diagram showing the arrangement of the color determining means 140 in the third embodiment.

The lightness judging means 1101 inside the color judging means 140 makes the same judgment as the lightness judging means 61 in the above-described second embodiment. That is, JL1 = 0 when the lightness L for the input target pixel is in an intermediate range in the L, Ca, and Cb color spaces, and JL1 = 1 when the lightness is somewhat smaller or larger.
The signal which becomes becomes. The achromatic / chromatic color determining unit 1102 also performs the same determination as the achromatic / chromatic color determining unit 63 in the second embodiment, and performs the achromatic / chromatic color determination for the target pixel one pixel at a time. The signal KC1 is output.

The result of the determination is delayed by a plurality of lines by the delay means 1103, and the achromatic / chromatic color determination means 1
A total of nine 3 × 3 KC1 signals are supplied to 110.
For this reason, the delay unit 1103 has the configuration shown in FIG.

3 × 3 smoothing means 1104 to 110
At 6, the weighted integration is performed using the delay memory as in the first embodiment.

The saturation amount extracting means 1108 performs the same processing as in the first embodiment based on the weighted integrated Ca1_SM and Cb1_SM, and outputs a saturation signal S. Since S calculated here is an output for the (j + 1) th line, a signal obtained by delaying this by one line is output as S.

The lightness judging means 1107 is based on the weighted and integrated lightness signal L1_SM.
The signal JL2 is output in the same manner as 101.

The achromatic / chromatic color judging means 1109 uses FIG.
As shown in FIG. 3, the area is divided into three areas: a part that is clearly achromatic in the color space of Ca and Cb, a part that is clearly chromatic, and an intermediate part thereof.

[0083] Set as

Here, the values of the thresholds m and n vary according to the signal JL2 from the brightness determining means 1107. That is, when JL2 = 0, n = n0, m = m0 When JL2 = 1, n = n1, m = m1, where n0> n1 and m0> m1.

JL2 = 1 means that the weighted integrated L
This corresponds to the case where the value of 1_SM is less than a certain value (when it is darker than a certain value) or more than a certain value (when it is brighter to a certain extent), and when JL2 = 0, it indicates a case where it is at an intermediate position.

Thus, the achromatic / chromatic color judging means 111
0, the 3 × 3 signal KC1 from the delay unit 1103
And j output from the achromatic / chromatic color determination unit 1109
The signal KC2 for the target pixel position obtained by delaying KC2 for the +1 line by one line is supplied in synchronization.

The achromatic / chromatic color determination means 1110 generates and outputs a signal KC indicating the final achromatic / chromatic color determination result based on these signals. The conditions are as follows. A determination result KC2 of the achromatic / chromatic color determination unit 1109
Indicates an achromatic color → the output signal KC is an achromatic color. The determination result KC2 of the achromatic / chromatic color determining unit 1109
Indicates a chromatic color → the output signal KC is a chromatic color / achromatic / chromatic color determination result KC2 of the determination means 1109
Is an intermediate part (when it is not possible to narrow down to either a chromatic or achromatic color) → 9 in the determination result KC1 (3 × 3 KC1 area) of the achromatic / chromatic color determination unit 1103 If the majority of the pixels are achromatic, the output signal KC is achromatic, and if the majority of the nine pixels is chromatic, the output signal KC is chromatic.

As described above, in the third embodiment, the line memory is used to synchronize the delay memories 1103, KC1, KC2, and S in order to area-process the determination result for each pixel. As shown in FIG. 14, j + of L1, Ca1, Cb1 output from the delay unit 103C.
By employing a configuration in which the lightness determination and the achromatic / chromatic color determination are performed using the data of three lines of 2, j + 1, j, the memory can be omitted and the cost can be reduced.

As described above, according to the first to third embodiments, it is possible to suppress the influence of noise and color misalignment and to perform more accurate color judgment. Eliminating erroneous determinations in portions where determination is easy can realize a higher quality color image.

Although the means for forming a color image has not been particularly described, for example, a laser beam printer or another method such as an ink jet printer may be used. In the case of a laser beam printer, by utilizing a technique such as PWM, printing may be performed in accordance with the finally obtained data of C4, M4, Y4, and K4. By known binarization means (for example, a dither method or an error diffusion method),
Then print it.

In the embodiment, the case where the present invention is mainly applied to a copying machine has been described. However, even if the input source of the image data is an image scanner at first, the input source is an intermediate input via a storage medium. The present invention is not limited by the above embodiment, since the present invention can be applied to the case where the input is made via a communication line. Also, the output means may not be directly output to the printer but output to a storage medium or transmitted to a partner terminal (for example, a facsimile machine) via a line.

Therefore, even if the present invention is applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), an apparatus (for example, a copying machine, a facsimile machine) comprising one device Device).

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 device or apparatus such as a personal computer, and to provide a computer (not shown) of the system or apparatus. Alternatively, it is needless to say that the present invention can also be achieved by a CPU or an MPU) 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, CD-ROM, and CD.
-R, a magnetic tape, a nonvolatile memory card, a ROM, or 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.

[0098]

As described above, according to the present invention,
It is possible to accurately determine the achromatic color / chromatic color of each pixel in the input color image data.

Accordingly, it is possible to suppress the influence of noise included in the input color image and the color shift of the image scanner or the like. For example, when printing, it is possible to output a high-quality image.

[0100]

[Brief description of the drawings]

FIG. 1 is a block diagram of a device according to a first embodiment.

FIG. 2 is a block diagram of the vicinity of delay means 103B in FIG. 1;

FIG. 3 is a block configuration diagram of a color determination unit 120 according to the first embodiment.

FIG. 4 is a diagram showing a weighted average coefficient for smoothing in a color determination unit 120;

FIG. 5 is a block diagram of an apparatus according to a second embodiment.

FIG. 6 is a block diagram of a color determination unit 130 in FIG. 5;

FIG. 7 is a diagram illustrating a range to which a threshold is applied for each color region in the second embodiment.

FIG. 8 is a diagram showing a range to which a threshold value based on a brightness range in the second embodiment extends.

FIG. 9 is a block diagram of a device according to a third embodiment.

FIG. 10 is a block diagram showing the vicinity of a delay unit 103C in FIG. 9;

FIG. 11 is a block diagram of a color determination unit 140 in FIG. 9;

FIG. 12 is a block diagram of a delay unit 1103 in FIG. 11;

13 is an achromatic / chromatic color determining unit 11 in FIG.
It is a figure which shows the distribution of the determination result in 09.

FIG. 14 is a diagram illustrating another block configuration diagram of a color determination unit according to the third embodiment.

FIG. 15 shows a spatial filter coefficient storage unit 11 shown in FIG.
FIG. 3 is a diagram illustrating a filter stored in a second filter;

Claims (39)

[Claims] 1. An image processing apparatus for determining an attribute of each pixel based on color image data of a color space represented by a lightness signal and a chromaticity signal, comprising: Means for calculating a saturation amount based on the input chromaticity signal in the predetermined area; and determining whether the target pixel is an achromatic color or a chromatic color based on the saturation amount obtained by the calculation. And an image processing apparatus. 2. The image processing apparatus according to claim 1, further comprising a switching unit that switches a process for the input color image data based on a result of the determination unit. 3. The calculating means calculates a weighted average value for the chromaticity of the pixel of interest based on the input chromaticity signal of the predetermined area, and calculates a saturation amount based on the regenerated weighted average value. The image processing apparatus according to claim 1, wherein: 4. A reading means for reading an original image as color image data; and a converting means for converting the read color image data into a brightness signal and a chromaticity signal. The image processing apparatus according to claim 1, wherein a chromaticity signal is input by the input unit. 5. An image processing apparatus for determining an attribute of each pixel based on color image data in a color space represented by a lightness signal and a chromaticity signal, wherein a saturation amount is calculated based on the chromaticity signal. Calculating means for determining whether a pixel of interest belongs to a predetermined color area based on the chromaticity signal; and setting a threshold value based on a result of the determination by the first determining means. Threshold setting means, and a second determining means for comparing the saturation amount calculated by the calculating means with the threshold value set by the threshold setting means to determine whether the pixel of interest is achromatic or chromatic. An image processing apparatus characterized by the above-mentioned. 6. The image processing apparatus according to claim 5, wherein the first determination unit determines whether the color of the pixel of interest is in a blue or green region. 7. An image processing apparatus for determining an attribute of each pixel based on color image data in a color space represented by a lightness signal and a chromaticity signal, wherein a saturation amount is calculated based on the chromaticity signal. Calculating means for determining the degree of brightness of the pixel of interest based on the brightness signal; threshold setting means for setting a threshold based on the determination result of the determining means; An image processing apparatus comprising: a determination unit configured to compare the calculated saturation amount with a threshold set by the threshold setting unit and determine whether the target pixel is an achromatic color or a chromatic color. 8. The image processing apparatus according to claim 7, wherein the determination unit determines whether or not the brightness of the pixel of interest is in an intermediate brightness region that is equal to or more than a predetermined value and equal to or less than a predetermined value. . 9. An image processing apparatus for determining an attribute of each pixel based on color image data in a color space represented by a lightness signal and a chromaticity signal, comprising: a first and a second achromatic / chromatic color; Determining means for calculating a saturation amount based on the chromaticity signal; and determining whether a pixel of interest belongs to a predetermined color area based on the chromaticity signal. First determining means for determining whether or not the pixel of interest belongs to a predetermined color area, and first threshold setting means for setting a first threshold value when the first determining means determines that the pixel of interest belongs to a predetermined color area. And a second determination means for determining whether the pixel of interest is an achromatic color or a chromatic color based on the saturation amount calculated in step (a) and the threshold value set by the first threshold value setting means. The coloring determination unit determines that the target pixel is a predetermined color by the first determination unit; When it is determined that the pixel does not belong to the area, a third determination unit that determines the degree of brightness of the pixel of interest based on the brightness signal, and a threshold is set based on a determination result of the second determination unit. A second threshold value setting unit that compares the saturation amount calculated by the calculation unit with the threshold value set by the second threshold value setting unit, and determines whether the target pixel is an achromatic color or a chromatic color. An image processing apparatus comprising: a determination unit. 10. The image processing apparatus according to claim 9, wherein the first determination unit determines whether the color of the target pixel is in a blue or green region. 11. The apparatus according to claim 9, wherein said third determination means determines whether or not the brightness of the pixel of interest is in an intermediate brightness region of a predetermined value or more and a predetermined value or less. Image processing device. 12. A storage unit for storing a result determined by the third or fourth determination unit, and calculating an average chroma amount at a pixel position of interest based on a plurality of chromaticity signals around the pixel of interest. Means for calculating the amount of average saturation, identification means for determining whether the pixel of interest is achromatic, chromatic, or at an intermediate position based on the calculated amount of average saturation; Alternatively, when the image is identified as an achromatic color, the identification result is output, and when the image is identified as being at the intermediate position, the image is focused based on a plurality of determination results around the pixel of interest stored in the storage unit. 10. The image processing apparatus according to claim 9, further comprising: third achromatic / chromatic color determining means for determining achromatic / chromatic color of a pixel. 13. An average lightness calculating means for calculating an average lightness at a target pixel position based on a plurality of lightness signals around the target pixel; 13. The image processing apparatus according to claim 12, further comprising a threshold value adjusting unit that adjusts a threshold value for identifying a chromatic color, a chromatic color, and whether or not the chromatic color is at an intermediate position. 14. An image processing method for determining an attribute of each pixel based on color image data of a color space represented by a lightness signal and a chromaticity signal, wherein the chromaticity signal is input in a predetermined area unit. Calculating an amount of saturation based on the input chromaticity signal in the predetermined area; and determining whether the pixel of interest is achromatic or chromatic based on the amount of saturation obtained by the operation. And an image processing method. 15. The image processing method according to claim 14, further comprising a switching step of switching a process for input color image data based on a result of the determination step. 16. The calculating step calculates a weighted average value for the chromaticity of the pixel of interest based on the input chromaticity signal of the predetermined area, and calculates a saturation amount based on the regenerated weighted average value. The image processing method according to claim 14, wherein: 17. A reading step for reading a document image as color image data; and a converting step for converting the read color image data into a brightness signal and a chromaticity signal. The image processing method according to claim 14, wherein a chromaticity signal is input in the input step. 18. An image processing method for determining an attribute of each pixel based on color image data in a color space represented by a lightness signal and a chromaticity signal, wherein a saturation amount is calculated based on the chromaticity signal. A first determining step of determining whether or not the pixel of interest belongs to a predetermined color area based on the chromaticity signal; and setting a threshold value based on a determination result of the first determining step. And a second determination step of comparing the saturation amount calculated in the calculation step with the threshold value set in the threshold value setting step to determine whether the pixel of interest is an achromatic color or a chromatic color. An image processing method comprising: 19. The image processing method according to claim 18, wherein the first determining step determines whether or not the color of the pixel of interest is in a blue or green region. 20. An image processing method for determining an attribute of each pixel based on color image data in a color space represented by a lightness signal and a chromaticity signal, wherein a saturation amount is calculated based on the chromaticity signal. A determining step of determining the degree of brightness of the pixel of interest based on the brightness signal; a threshold setting step of setting a threshold based on the determination result of the determining step; An image processing method comprising: comparing the calculated saturation amount with a threshold set in the threshold setting step to determine whether the target pixel is an achromatic color or a chromatic color. 21. The image processing method according to claim 20, wherein the determining step determines whether or not the brightness of the pixel of interest is in an intermediate brightness region of a predetermined value or more and a predetermined value or less. . 22. An image processing method for determining an attribute of each pixel based on color image data in a color space represented by a lightness signal and a chromaticity signal, comprising: first and second achromatic / chromatic colors. A first achromatic / chromatic color determining step; a calculating step of calculating a saturation amount based on the chromaticity signal; and whether the pixel of interest belongs to a predetermined color area based on the chromaticity signal. A first determination step of determining whether or not the pixel of interest belongs to a predetermined color area in the first determination step; a first threshold value setting step of setting a first threshold value; And a second determination step of determining whether the pixel of interest is an achromatic color or a chromatic color based on the saturation amount calculated in the above and the threshold value set in the first threshold value setting step. In the coloring determination step, the target pixel is determined by the first determination step. When it is determined that the pixel does not belong to the region, a third determination step of determining the degree of brightness of the pixel of interest based on the brightness signal, and a threshold value is set based on the determination result of the second determination step. A second threshold value setting step, and a fourth step of comparing the saturation amount calculated in the calculation step with the threshold value set in the second threshold value setting step to determine whether the target pixel is an achromatic color or a chromatic color. An image processing method comprising: a determination step. 23. The image processing method according to claim 22, wherein the first determination step determines whether or not the color of the target pixel is in a blue or green region. 24. The apparatus according to claim 22, wherein the third determination step determines whether or not the brightness of the pixel of interest is in an intermediate brightness region of a predetermined value or more and a predetermined value or less. Image processing method. 25. A storage step of storing a result determined in the third or fourth determination step, and calculating an average chroma amount at a pixel position of interest based on a plurality of chromaticity signals around the pixel of interest. Calculating an average saturation amount to be performed; identifying the target pixel based on the calculated average saturation amount to determine whether the pixel of interest is an achromatic color, a chromatic color, or an intermediate position between the pixels; Alternatively, when the pixel is identified as an achromatic color, the identification result is output, and when the pixel is identified as being at an intermediate position, the pixel is focused based on a plurality of determination results around the pixel of interest stored in the storage step. 23. The image processing method according to claim 22, further comprising a third achromatic / chromatic color determining step of determining achromatic / chromatic color of the pixel. 26. An average lightness calculating step of calculating an average lightness at a pixel position of interest based on a plurality of lightness signals around the pixel of interest. 26. The image processing method according to claim 25, further comprising a threshold value adjusting step of adjusting a threshold value for identifying a chromatic color, a chromatic color, and whether or not the chromatic color is at an intermediate position. 27. A storage medium storing a program code for determining an attribute of each pixel based on color image data in a color space represented by a lightness signal and a chromaticity signal, wherein the chromaticity signal is stored in a predetermined area A program code for an input step, a program code for an operation for calculating a saturation amount based on the input chromaticity signal in the predetermined area, and a pixel of interest based on the saturation amount obtained by the calculation. And a program code for a determination step of determining whether the color is achromatic or chromatic. 28. The storage medium according to claim 27, further comprising a program code of a switching step of switching processing of color image data input based on a result of said determining step. 29. The calculating step calculates a weighted average value for the chromaticity of the pixel of interest based on the input chromaticity signal of the predetermined area, and calculates a saturation amount based on the regenerated weighted average value. 28. The storage medium according to claim 27, wherein: 30. A computer program for reading a document image as color image data, and a program code for a conversion step for converting the read color image data into a brightness signal and a chromaticity signal. 28. The storage medium according to claim 27, wherein the brightness and chromaticity signals obtained in step (b) are input in the input step. 31. A storage medium for determining an attribute of each pixel based on color image data in a color space represented by a lightness signal and a chromaticity signal, wherein a saturation amount is calculated based on the chromaticity signal. A program code for a calculation step; a program code for a first determination step for determining whether or not the pixel of interest belongs to a predetermined color region based on the chromaticity signal; and a determination result for the first determination step. Comparing the program code of the threshold setting step for setting the threshold value, the saturation amount calculated in the calculating step with the threshold value set in the threshold setting step, and determining whether the target pixel is an achromatic color or a chromatic color. And a program code for a second determination step. 32. The storage medium according to claim 31, wherein the first determination step determines whether or not the color of the pixel of interest is in a blue or green region. 33. A storage medium for determining an attribute of each pixel unit based on color image data in a color space represented by a lightness signal and a chromaticity signal, wherein a saturation amount is calculated based on the chromaticity signal. A program code for an operation step, a program code for a determination step of determining the degree of brightness of the pixel of interest based on the brightness signal, and a program code for a threshold setting step for setting a threshold based on the determination result of the determination step And comparing the saturation amount calculated in the calculation step with the threshold value set in the threshold value setting step, and comprising a program code of a determination step of determining whether the pixel of interest is an achromatic color or a chromatic color. Storage media. 34. The storage medium according to claim 33, wherein said determining step determines whether or not the brightness of the pixel of interest is in an intermediate brightness region of a predetermined value or more and a predetermined value or less. 35. A storage medium for determining an attribute of each pixel based on color image data in a color space represented by a lightness signal and a chromaticity signal, wherein the first and second achromatic / chromatic color determinations are performed. A first achromatic / chromatic color determining step, wherein a target pixel is determined based on the chromaticity signal based on the program code of an arithmetic step of calculating a saturation amount based on the chromaticity signal. A program code for a first determination step for determining whether or not the pixel of interest belongs to a color area; A second determination for determining whether the pixel of interest is an achromatic color or a chromatic color based on the program code of the threshold value setting step, the saturation amount calculated in the calculation step, and the threshold value set in the first threshold value setting step Process program A second achromatic / chromatic color determination step, wherein when the first determination step determines that the target pixel does not belong to the predetermined color area, the brightness of the target pixel is determined based on the brightness signal. And a program code for a second threshold setting step for setting a threshold based on the determination result of the second determination step. A storage medium characterized by comprising a program code of a fourth determination step of comparing the saturation amount with a threshold value set in the second threshold value setting step and determining whether the target pixel is an achromatic color or a chromatic color. . 36. The storage medium according to claim 35, wherein the first determination step determines whether or not the color of the pixel of interest is in a blue or green region. 37. The method according to claim 35, wherein the third determination step determines whether or not the brightness of the pixel of interest is in an intermediate brightness region of a predetermined value or more and a predetermined value or less. Storage medium. 38. A program code of a storage step for storing a result determined in the third or fourth determination step, and an average color at a target pixel position based on a plurality of chromaticity signals around the target pixel. A program code for an average saturation calculation step for calculating the degree of saturation, and a program code for an identification step for identifying whether the pixel of interest is achromatic, chromatic, or at an intermediate position based on the calculated average saturation. If the image is identified as a chromatic or achromatic color in the identification step, the identification result is output, and if the pixel is identified as being at an intermediate position, the vicinity of the pixel of interest stored in the storage step is output. 36. The program according to claim 35, further comprising a third achromatic / chromatic color determining step of determining achromatic / chromatic color of the pixel of interest based on the plurality of determination results. Of the storage medium. 39. A program code for an average brightness calculation step for calculating an average brightness at a pixel position of interest based on a plurality of brightness signals around the pixel of interest, and the identification based on the average brightness obtained by the calculation. 39. The storage medium according to claim 38, further comprising: a program code for a threshold adjustment step of adjusting a threshold for identifying whether an achromatic color, a chromatic color, or an intermediate position exists in the step.