JP2002320100A - Image processor, computer-readable recording medium having image processing program recorded thereon, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To satisfactorily sharpen even an input image free from the change of brightness without changing the color of the input image. SOLUTION: This image processor includes an HIS conversion part 20 for converting image data consisting of three components of red(R), green(G) and blue(B) to a hue(H), saturation(S) and brightness(I), an edge emphasizing part 21 connected to the part 20 for applying edge emphasis to the saturation and brightness, a saturation correcting part 22 connected to the part 20 and the part 21 to correct edge-emphasized saturation based on the saturation outputted from the part 20, and an HIS inverse conversion part 23 connected to the part 20, the part 21 and the part 22 to convert the values of a component H, a component S and a component I to the values of a component R, a component G and a component B.

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, a computer-readable recording medium storing an image processing program, and a program, and more particularly to an image processing capable of performing sharpening without changing the color tone of a color image. The present invention relates to an apparatus, a computer-readable recording medium storing an image processing program, and a program.

[0002]

2. Description of the Related Art Generally, in a process for sharpening a blurred image, an edge enhancement process for enhancing a high-frequency region of image data is performed. If the input image is a monochrome image, the blurred image can be favorably sharpened by using this processing. However, when the input image is a color image, it is simply RGB (red, green, blue) or CMY
When edge enhancement processing is performed on each color component such as (cyan, magenta, and yellow), a sharp image is obtained as in the case of a monochrome image, but the hue and saturation of the edge portion are changed. The color will change compared to. For example, in an image in which black and blue lines intersect on a white background, an original color may appear, for example, the boundary between the black and blue lines becomes yellow.

In a television or a video camera, a technique of converting a color image into a luminance component and a color difference component and performing edge enhancement processing on the luminance component to sharpen the image is generally used. According to this method, sharpening can be performed relatively favorably on a natural image or the like. However, for example, in an image in which a red or blue line is written on a white background, the color of the red or blue line may change to black due to the edge enhancement processing because the red and blue luminance components are small. . Conversely, a colored line drawn on a dark background may be lightened by the edge enhancement processing.

In order to solve such a problem, a color tone image information edge enhancement processing apparatus disclosed in Japanese Patent Application Laid-Open No. 61-273073 extracts lightness from input image data, and To perform edge enhancement processing. A correction coefficient is obtained from the result, and sharpening is performed by multiplying each color component (cyan (C), magenta (M), yellow (Y)) of the input image data by the correction coefficient. In this method, the C, M, and Y components are multiplied by the same coefficient. For this reason, it is possible to perform sharpening without shifting the input and output hues.

[0005]

However, each of the C component, the M component and the Y component has a finite value. For this reason,
When the scaling process is performed based on brightness, the value becomes 0,
Or saturate. As a result, the image becomes whitish or blackish, and the saturation changes.

Further, when only the saturation and the hue change without changing the brightness, edge enhancement cannot be performed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and an object of the present invention is to sharpen even an input image having no change in brightness without changing the color tone of the input image. An object of the present invention is to provide an image processing apparatus capable of performing the processing, a computer-readable recording medium storing an image processing program, and a program.

Another object of the present invention is to provide an image processing apparatus capable of satisfactorily sharpening an input image having no change in saturation as well as brightness without changing the hue of the input image. An object of the present invention is to provide a computer-readable recording medium on which an image processing program is recorded and a program.

[0009]

An image processing apparatus according to an aspect of the present invention sharpens a color image. Image data is represented by hue, saturation, and brightness. The image processing device is connected to a saturation edge enhancement unit for enhancing a saturation edge of the image data, a brightness edge enhancement unit for enhancing a brightness edge of the image data, and a saturation edge enhancement unit. A saturation correction unit for correcting the saturation output from the saturation edge enhancement unit based on the saturation of the image data before edge enhancement.

No processing is performed on the hue of the image data, and the edge enhancement processing is performed only on the brightness and the saturation. Therefore, sharpening can be performed while maintaining the color tone of the original image. In addition, edge enhancement is performed not only for lightness but also for saturation. Therefore, it is possible to sharpen even an image having no change in brightness.

Preferably, the image processing apparatus further includes a first conversion unit for converting image data in which each pixel is represented by coordinates in a predetermined color space into image data represented by hue, saturation, and lightness. Including means. The saturation edge enhancement means is connected to the first conversion means, and includes means for enhancing the saturation edge of the image data output from the first conversion means. The brightness edge enhancing means is connected to the first converting means and includes means for enhancing the brightness edge of the image data output from the first converting means. The saturation correction unit is connected to the first conversion unit and the saturation edge enhancement unit, and based on the saturation of the image data output from the first conversion unit, the saturation output from the saturation edge enhancement unit. Is included.

More preferably, the image processing apparatus is further connected to a first conversion unit, a saturation correction unit, and a brightness edge enhancement unit, and outputs a hue and a saturation output from the first conversion unit. And a second conversion unit for converting the image data represented by the brightness output from the saturation and brightness edge enhancement unit into coordinates in a predetermined color space.

[0013] More preferably, the saturation correction means is configured to adjust the saturation output from the edge enhancement means to an image before edge enhancement only when the saturation output from the edge enhancement means is smaller than a predetermined value. Allow to be less than the saturation of the data.

Therefore, it is possible to prevent the edge portion from changing to white. Accordingly, the originally whitish portion can be emphasized more white.

An image processing apparatus according to another aspect of the present invention comprises:
Performs sharpening of color images. The image processing apparatus calculates, from the image data in which each pixel value is represented by coordinates in a predetermined color space,
Hue extraction means for extracting hue, saturation extraction means for extracting saturation from image data, color component enhancement means for enhancing edges of image data for each color component, and color component enhancement Means for converting the image data, the edge of which has been enhanced by the color component enhancing means, into image data represented by hue, saturation and brightness.
Is connected to the hue extracting means and the first converting means, and based on the hue outputted from the hue extracting means,
A hue correction unit for correcting the hue output from the first conversion unit, a saturation extraction unit and a hue correction unit connected to the first conversion unit, based on the saturation output from the saturation extraction unit;
And a saturation correction unit for correcting the saturation output from the first conversion unit.

Edge enhancement is performed on each color component of the input image data. For this reason, it is possible to sharpen even image data having a constant saturation as well as brightness.

Preferably, the image processing apparatus is further connected to a hue correction unit, a saturation correction unit, and a first conversion unit, and the hue output from the hue correction unit and the saturation output from the saturation correction unit. And a second conversion unit for converting the brightness output from the first conversion unit into coordinates in a predetermined color space.

[0018] More preferably, the saturation correction means includes:
The saturation output from the first conversion unit is smaller than the saturation output from the saturation extraction unit only when the saturation output from the conversion unit is smaller than a predetermined value. Allow.

Therefore, it is possible to prevent the edge portion from turning white. Accordingly, the originally whitish portion can be emphasized more white.

More preferably, the saturation correction means limits the rate of change of saturation to a predetermined value or less. It limits the rate of change of saturation. For this reason, it is possible to prevent the occurrence of overexposure (local white spot) and unintended color due to extreme changes in saturation.

More preferably, the saturation correction hand throwing limits the amount of change in saturation to a predetermined value or less. The amount of change in saturation is limited. For this reason, it is possible to prevent the occurrence of overexposure and unintended colors due to extreme changes in saturation.

More preferably, the hue correction means limits the amount of change in hue to a predetermined value or less. Therefore, it is possible to prevent the input image from being changed to an unintended color by the edge enhancement processing, and it is possible to perform sharpening while maintaining the color tone of the original image.

More preferably, the color space represented by hue, saturation and lightness is represented by a hexagonal pyramid color model.

In the hexagonal pyramid color model, the brightness is R (red)
Value, G (green) value and B (blue) value. Therefore, for example, even in an image in which a red blurred line is drawn on a white background, there is no change in lightness, so that the color does not change to black due to edge emphasis on lightness.

An image processing method according to still another aspect of the present invention performs sharpening of a color image. The image processing method is
Enhancing the saturation edge of the image data, enhancing the brightness edge of the image data, and correcting the saturation of the image data after the edge enhancement based on the saturation of the image data before the edge enhancement. Steps.

No processing is performed on the hue of the image data, and the edge enhancement processing is performed only on the brightness and the saturation. Therefore, sharpening can be performed while maintaining the color tone of the original image. In addition, edge enhancement is performed not only for lightness but also for saturation. Therefore, it is possible to sharpen even an image having no change in brightness.

An image processing method according to still another aspect of the present invention performs sharpening of a color image. The image processing method is
Extracting a hue from the image data in which each pixel value is represented by predetermined coordinates; extracting a saturation from the image data; enhancing an edge of the image data for each color component; Converting the image data in which the color is enhanced to image data represented by hue, saturation, and lightness; correcting the hue after edge enhancement based on the hue before edge enhancement; Correcting the saturation after the edge enhancement based on the degree.

Edge enhancement is performed on each color component of the input image data. For this reason, it is possible to sharpen even image data having a constant saturation as well as brightness.

According to still another aspect of the present invention, there is provided a computer-readable recording medium comprising: a step of enhancing a saturation edge of image data; a step of enhancing a lightness edge of image data; And a step of correcting the saturation of the image data after the edge enhancement based on the saturation of the image data.

The processing is not performed on the hue of the image data, and the edge enhancement processing is performed only on the brightness and the saturation. Therefore, sharpening can be performed while maintaining the color tone of the original image. In addition, edge enhancement is performed not only for lightness but also for saturation. Therefore, it is possible to sharpen even an image having no change in brightness.

A computer-readable recording medium according to still another aspect of the present invention includes a step of extracting hue from image data in which each pixel value is represented by predetermined coordinates, and a step of extracting saturation from image data. Performing the step of emphasizing the edges of the image data for each color component; converting the image data having the emphasized edges into image data represented by hue, saturation, and lightness; An image processing program for causing a computer to execute a step of correcting the hue after edge enhancement based on the color saturation and a step of correcting the saturation after edge enhancement based on the saturation before edge enhancement is recorded.

Edge enhancement is performed on each color component of the input image data. For this reason, it is possible to sharpen even image data having a constant saturation as well as brightness.

According to still another aspect of the present invention, there is provided a program for causing a computer to enhance a saturation edge of image data, enhance a lightness edge of image data, and enhance a color of image data before edge enhancement. Correcting the saturation of the image data after edge enhancement based on the degree.

No processing is performed on the hue of the image data, and the edge enhancement processing is performed only on the brightness and the saturation. Therefore, sharpening can be performed while maintaining the color tone of the original image. In addition, edge enhancement is performed not only for lightness but also for saturation. Therefore, it is possible to sharpen even an image having no change in brightness.

According to still another aspect of the present invention, there is provided a program for causing a computer to extract a hue from image data in which each pixel value is represented by predetermined coordinates, and to extract a saturation from image data. Enhancing the edge of the image data for each color component, converting the image data with the enhanced edge into image data represented by hue, saturation and lightness, based on the hue before edge enhancement. And a step of correcting the hue after the edge enhancement and the step of correcting the saturation after the edge enhancement based on the saturation before the edge enhancement.

Edge enhancement is performed on each color component of the input image data. For this reason, it is possible to sharpen even image data having a constant saturation as well as brightness.

[0037]

Embodiments of the present invention will be described below in detail with reference to the drawings.

[First Embodiment] Referring to FIG. 1, an image processing apparatus according to a first embodiment of the present invention includes a computer main body 1, a graphic display device 2,
FD drive 3 to which FD (Flexible Disc) 4 is mounted
, Keyboard 5, mouse 6, and CD-ROM (Comp
act-Disc-Read Only Memory) 8 CD-R
An OM device 7 and a network communication device 9 for transmitting and receiving data to and from an external computer or the like via a network
Computer main unit 1, graphic display device 2, FD drive 3, keyboard 5, mouse 6, CD
And a bus for interconnecting the ROM device 7 and the network communication device 9.

The computer body 1 has a CPU (Central
Processing Unit) 10, ROM (Read Only Memory)
11, a RAM (Random Access Memory) 12 and a hard disk 13.

The CPU 10 includes a graphic display device 2, an FD drive 3, a keyboard 5, a mouse 6, a C
D-ROM device 7, network communication device 9, ROM1
1. The processing is performed while inputting / outputting data to / from the RAM 12 or the hard disk 13. FD4 or CD-
The image processing program recorded in the ROM 8 is the CPU 1
0 is temporarily stored in the hard disk 13 via the FD live 3 or the CD-ROM device 7. CPU10
Is executed by loading an image processing program from the hard disk 13 into the RAM 12 and executing the program.
The processing for the image data stored in the storage unit 12 is executed.
The image processing program may be supplied from another computer via a communication line to the computer main body 1 from the network communication device 9.

Referring to FIG. 2, a functional configuration of the image processing apparatus according to the present embodiment will be described. The image processing apparatus converts an image data composed of three components of red (R), green (G), and blue (B) into hue (H), saturation (S), and lightness (I). 20 and HSI conversion unit 2
0, an edge enhancement unit 21 for performing edge enhancement on saturation and brightness, a saturation correction unit 22 connected to the HSI conversion unit 20 and the edge enhancement unit 21 for correcting edge-enhanced saturation, and an HSI Conversion unit 20, edge enhancement unit 21
And an HSI inverse conversion unit 23 connected to the saturation correction unit 22 for converting the values of the H, S, and I components into the values of the R, G, and B components.

The format of the input / output image data is not limited to the RGB format but may be the CMY format. Further, the input and output may have different formats, for example, the input is in RGB format and the output is in CMY format.

The HSI is sometimes expressed as HSV (hue, saturation, brightness) or HSL (hue, saturation, luminance), but the meaning is the same.

The processing executed by the image processing apparatus will be described with reference to FIG. The HSI conversion unit 20 converts the input image data into HSI format image data (S
1). The edge enhancement unit 21 performs an edge enhancement process on the S component and the I component (S2). Saturation correction unit 22
Corrects the edge emphasized saturation (S) (S3).
The HSI inverse conversion unit 23 converts the image data including the H component output from the HSI conversion unit 20, the S component output from the saturation correction unit 22, and the I component output from the edge enhancement unit 21 into RGB format image data. And output (S
4). Methods for converting the RGB format to the HSI format and the reverse conversion method from the HSI format to the RGB format are known technologies. Therefore, the detailed description will not be repeated here.

Referring to FIG. 4, FIG. 5 and FIG.
2 shows the relationship between the space and the RGB space. With this, RGB
The relationship between the value of the HSI format and the value of the HSI format is shown.
1 and S4 are realized.

In this embodiment, an HSI hexagonal pyramid color model is used as a model representing the HSI space. HS
For the I6 pyramid color model, see Jan. 17, 1991.
Pages 486 to 48 of the "Image Analysis Handbook" (published by the University of Tokyo), edited by Mikio Takagi and Hirohisa Shimoda, published daily
This is a general color model as shown in detail on page 9.

Considering a cube that touches three axes in the RGB orthogonal coordinate system, R, G, and B and their complementary colors C, M, and Y have a positional relationship as shown in FIG. The main diagonal axis of this RGB cube is defined as a lightness axis I. Then, a hexagonal pyramid color model as shown in FIG. 5 is obtained. The brightness of a point P in the hexagonal pyramid color model is defined as the maximum value of the R value, G value, and B value of the point P. FIG. 6 shows a plane passing through the point P and orthogonal to the brightness axis I. Assuming that a point at which the lightness axis I intersects with the plane is W, the hue (H) is defined as an angle between WR and WP, and an intersection of an extension of WP and the hexagon is E
Then, the saturation (S) is defined as WP / WE. Note that the model representing the HSI space may be another model.

Referring to FIG. 7, the processing in S2 of FIG. 3 will be described. FIG. 7 is a diagram illustrating each coefficient of the edge enhancement filter. a is a parameter for adjusting the strength of edge enhancement. The edge emphasis of the pixel of interest is obtained by subtracting the value of the pixel in the vicinity 8 by (a / 8) from the result of multiplying the value of the pixel of interest by (a + 1). In the case of saturation edge enhancement, the pixel value is S
In the case of brightness edge enhancement using a component, the I component is used as a pixel value. Note that the result of the filtering is limited by the value range of each component. This filter processing emphasizes changes in saturation and lightness.

Referring to FIG. 8, the processing (saturation correction) in S3 of FIG. 3 will be described. The saturation before the edge enhancement is S0, the saturation after the edge enhancement is S1, and the saturation after the saturation correction is S2. The saturation correction unit 22 calculates S1 and S
A value of 0 is compared (S10). If S1 is larger than S0 (YES in S10), the smaller of S1 and S1 is set as S2 (S11). S1
Is smaller than S0 (NO in S10, YE in S12)
S), if S0 is 0.2 or less (YE in S13)
S) S1 is set to S2 (S14). S other than above
0 is set as S2 (S15).

As described above, when the original saturation is small (S
Only in case of NO at S10, YES in S12 and YES in S13), the reduction of the saturation by the processing of the edge emphasizing unit 21 is allowed (S14). Therefore, it is possible to prevent the edge portion from changing to white. Accordingly, the originally whitish portion can be emphasized more white. Also, by limiting the rate of increase in saturation (S1
1) It is possible to prevent an unintended color from appearing in an originally uncolored portion.

[Modification 1 of Saturation Correction] Referring to FIG.
Another saturation correction process in the saturation correction unit 22 will be described. When the saturation S1 after the edge enhancement is larger than the saturation S0 before the edge enhancement (YE in S20)
S) sets the smaller value of the value obtained by multiplying S0 by 1.5 and S1 as the corrected saturation S2 (S21), and in the other cases, the value obtained by multiplying S0 by 0.5 and S1 The larger value is set to S2 (S22).

[Second Modification of Saturation Correction] Still another saturation correction processing in the saturation correction section 22 will be described with reference to FIG. If S1 is larger than S0 (YES in S25), the smaller of S1 and 0.1 and S1 is set as S2 (S26), otherwise, 0.1 is subtracted from S0. The larger value of the calculated value and S1 is defined as S2 (S27).

Both Modifications 1 and 2 have the same effect as the processing shown in FIG. As described above, according to the image processing apparatus of the present embodiment, the hue is not processed, and only the brightness and the saturation are sharpened. Therefore, sharpening can be performed while maintaining the color tone of the original image. In addition, since edge enhancement is performed not only for brightness but also for saturation, it is possible to sharpen even an image having no change in brightness.

In the correction of the saturation, the rate at which the saturation changes or the amount of change is limited. For this reason, it is possible to prevent the occurrence of overexposure and unintended colors due to extreme changes in saturation.

In the HSI hexagonal pyramid color model, the lightness is the maximum value of the R value, G value and B value. For this reason,
For example, even if the image has a red blurred line drawn on a white background,
Since there is no change in lightness, the color does not change to black due to edge emphasis on lightness. Further, since the edge is enhanced with respect to the saturation, the blurred pixel changes to white or red, and the sharpening can be performed well.

[Second Embodiment] The schematic configuration of the hardware of an image processing apparatus according to a second embodiment of the present invention is the same as that of the image processing apparatus according to the first embodiment shown in FIG. It is. Therefore, the detailed description will not be repeated here.

Referring to FIG. 11, a functional configuration of the image processing apparatus according to the present embodiment will be described. The image processing apparatus includes an HS extraction unit 30 that extracts hue (H) and saturation (S) from input image data including three components of red (R), green (G), and blue (B); An edge emphasizing unit 31 that performs edge emphasis on the R, G, and B components of the data, respectively, and is connected to the edge emphasizing unit 31 to convert the edge-emphasized input image data into H (hue) and S (saturation). And an HSI conversion unit 32 for converting the image into I (brightness), the HS extraction unit 30 and the HSI conversion unit 32, and corrects the hue of the image after the edge enhancement based on the hue output from the HS extraction unit 30. Hue correction unit 3
3, a saturation correction unit 34 connected to the HS extraction unit 30 and the HSI conversion unit 32 and correcting the saturation of the image after edge enhancement based on the saturation output from the HS extraction unit 30;
An HSI inverse converter 35, which is connected to the hue corrector 33, the compressed native code storage area 34, and the HSI converter 32, and converts the values of the H, S, and I components into R, G, and B components; including.

The format of the input / output image data is not limited to the RGB format but may be the CMY format. Also, the input and output formats may be different, for example, the input is in RGB format and the output is in CMY format.

The input / output data may be in HSI format. In this case, the HSI conversion unit 32 and the HSI
The inverse converter 35 outputs the input data without doing anything.

Referring to FIG. 12, the processing executed by the image processing apparatus will be described. The HS extraction unit 30 extracts an H (hue) component and an S (saturation) component from the input image data (S30). The edge enhancement unit 31 performs an edge enhancement process on each of the R, G, and B components of the input image data (S31). HSI conversion unit 32
Converts the image data in RGB format with edge enhancement to HSI
The image data is converted into image data of a format (S32). Hue correction unit 3
No. 3 corrects the hue after the edge enhancement based on the hue before the edge enhancement (S33). The saturation correction unit 34 corrects the saturation after the edge enhancement based on the saturation before the edge enhancement (S
34). The HSI inverse conversion unit 35 converts the image data including the H component output from the hue correction unit 33, the S component output from the saturation correction unit 34, and the I component output from the HSI conversion unit 32 into RGB format image data. And output (S35). How to convert from RGB format to HSI format,
The method of inverse conversion from the HSI format to the RGB format is a known technique. Therefore, the detailed description will not be repeated here.

The HS extracting section 30 executes a process for extracting an H component and an S component from an image in the RGB format. This processing is a known technique as described above. Therefore, the detailed description will not be repeated here.

The edge emphasis unit 31, the HSI conversion unit 32, and the HSI inverse conversion unit 35 perform the same processing as the edge enhancement unit 21, the HSI conversion unit 20, and the HSI inverse conversion unit 23 in FIG. 2, respectively. Therefore, the detailed description thereof will not be repeated here.

The saturation correction section 34 is provided with the saturation correction section 22 shown in FIG.
The same processing as is performed. Therefore, the detailed description will not be repeated here. Note that the saturation S0 in the saturation correction unit 22 corresponds to the saturation S output from the HS extraction unit 30,
The saturation S1 corresponds to the saturation output from the HSI conversion unit 32.

Referring to FIG. 13, the processing (hue correction) in S33 of FIG. 12 will be described. The hue before edge enhancement is H0, the hue after edge enhancement is H1, and the hue after hue correction is H2. The hue correction unit 33 compares the values of H1 and H0 (S40), and when H1 is larger than H0 (YES in S40), the value obtained by adding 5 to H0 and H1
The smaller value is set as H2 (S41). H1 is H
If the value is equal to or less than 0 (NO in S40), the larger of the value obtained by subtracting 5 from H0 and H1 is set to H2 (S4).
2). The hue is an angle, and takes a value from 0 to 360. Further, there is a relationship of H = H ± 360.

As described above, according to the image processing apparatus of the present embodiment, the hue change during hue enhancement is limited by the hue correction processing. For this reason,
It is possible to prevent the input image from changing to an unintended color by the edge enhancement process, and it is possible to perform sharpening while maintaining the color tone of the original image. Further, since a change in hue is recognized to some extent, it is possible to sharpen even an image having no change in saturation and brightness.

Also, since edge enhancement is performed on each color component of the input image data, sharpening can be performed not only for brightness but also for image data having a constant saturation.

Further, a change in saturation during edge emphasis is limited by the saturation correction processing. For this reason, it is possible to prevent the occurrence of overexposure and unintended colors due to extreme changes in saturation.

The embodiments disclosed this time are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

[0069]

Even if the input image has no change in brightness,
The sharpening can be favorably performed without changing the color of the input image. In addition, even for an input image having no change in chroma as well as brightness, sharpening can be performed well without changing the hue of the input image.

[Brief description of the drawings]

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

FIG. 2 is a block diagram illustrating a functional configuration of the image processing apparatus according to the first embodiment of the present invention.

FIG. 3 is a flowchart of a process executed by the image processing device according to the first embodiment of the present invention.

FIG. 4 is a diagram showing an RGB space.

FIG. 5 is a diagram illustrating an HSI hexagonal pyramid color model.

FIG. 6 is a diagram for explaining H (hue) and S (saturation) using an HSI hexagonal pyramid color model.

FIG. 7 is a diagram illustrating coefficients of an edge enhancement filter.

FIG. 8 is a flowchart of a saturation correction process.

FIG. 9 is a flowchart of a first modification of the saturation correction process.

FIG. 10 is a flowchart of a second modification of the saturation correction process.

FIG. 11 is a block diagram illustrating a functional configuration of an image processing device according to a second embodiment of the present invention.

FIG. 12 is a flowchart of a process executed by the image processing device according to the second embodiment of the present invention.

FIG. 13 is a flowchart of a hue correction process.

[Explanation of symbols]

1 computer main body, 2 graphic display device, 3 FD drive, 4 FD, 5 keyboard,
6 mouse, 7 CD-ROM device, 8 CD-RO
M, 9 network communication device, 10 CPU, 11
ROM, 12 RAM, 13 hard disk, 20
HSI conversion unit, 21 edge enhancement unit, 22 saturation correction unit,
23 HSI inverse conversion unit, 30 HS extraction unit, 31 edge enhancement unit, 32 HSI conversion unit, 33 hue correction unit, 3
4 Saturation correction unit, 35 HSI inverse conversion unit.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H04N 9/68 103 H04N 1/46 Z F-term (Reference) 5B057 BA30 CA01 CA08 CA12 CA16 CB01 CB08 CB12 CB16 CC02 CE03 CE06 CE17 CE18 CH18 DA17 DC16 5C066 AA03 CA17 EC02 EE03 GA01 GA02 GA05 HA01 KC00 KP05 5C077 LL19 MP07 MP08 PP03 PP27 PP32 PP35 PP37 PP68 PQ08 PQ20 RR11 5C079 HB01 HB06 HB11 LA06 LA31 LB00 NA01

Claims (15)

[Claims] 1. An image processing apparatus for sharpening a color image, wherein the image data is represented by hue, saturation and lightness, and saturation edge enhancement for enhancing a saturation edge of the image data. Means, a brightness edge enhancing means for enhancing a brightness edge of the image data, and a saturation edge enhancing means connected to the saturation edge enhancing means, based on a saturation of the image data before edge enhancement. An image processing apparatus comprising: a saturation correction unit configured to correct saturation output from the unit. 2. The image processing apparatus according to claim 1, further comprising: first conversion means for converting image data in which each pixel is represented by coordinates in a predetermined color space into image data represented by hue, saturation, and lightness. The degree edge enhancing means is connected to the first converting means, and includes means for enhancing a saturation edge of image data output from the first converting means. The image processing apparatus further includes means connected to the first conversion means for enhancing a lightness edge of the image data output from the first conversion means, wherein the saturation correction means includes the first conversion means and the saturation. And means for correcting the saturation output from the saturation edge enhancement means based on the saturation of the image data output from the first conversion means, connected to the saturation edge enhancement means. Image processing according to 1. apparatus. 3. The hue output from the first conversion means and the hue output from the saturation correction means, the hue being connected to the first conversion means, the saturation correction means and the lightness edge enhancement means. 3. The image processing apparatus according to claim 2, further comprising a second conversion unit configured to convert image data represented by saturation and brightness output from the brightness edge enhancement unit into coordinates in a predetermined color space. 4. The saturation correction unit according to claim 1, wherein the saturation output from the edge enhancement unit is a color saturation before the edge enhancement only when the saturation output from the edge enhancement unit is smaller than a predetermined value. The image processing device according to claim 1, wherein the image processing device allows the saturation to be smaller than the saturation of the image data. 5. An image processing apparatus for sharpening a color image, comprising: a hue extracting means for extracting a hue from image data in which each pixel value is represented by coordinates in a predetermined color space; Saturation extraction means for extracting saturation from the image data; color component enhancement means for enhancing the edges of the image data for each color component; and the color component enhancement means connected to the color component enhancement means. Means for converting the image data whose edges are emphasized by the means into image data represented by hue, saturation, and brightness; and connected to the hue extraction means and the first conversion means, Based on the hue output from the hue extraction means,
A hue correction unit for correcting a hue output from the first conversion unit; a hue correction unit connected to the saturation extraction unit and the first conversion unit, based on the saturation output from the saturation extraction unit hand,
An image processing apparatus comprising: a saturation correction unit configured to correct saturation output from the first conversion unit. 6. The hue output from the hue correction means, the saturation output from the hue correction means, and the hue connected to the hue correction means, the saturation correction means and the first conversion means. The image processing apparatus according to claim 5, further comprising a second conversion unit configured to convert the lightness output from the first conversion unit into coordinates in a predetermined color space. 7. The saturation correction unit determines that the saturation output from the first conversion unit is only when the saturation output from the first conversion unit is smaller than a predetermined value. The image processing device according to claim 5, wherein the saturation is smaller than the saturation output from the saturation extracting unit. 8. The image processing apparatus according to claim 1, wherein the saturation correction unit limits a rate of change in saturation to a predetermined value or less. 9. The image processing apparatus according to claim 1, wherein said saturation correction hand throw limits a variation amount of saturation to a predetermined value or less. 10. The image processing apparatus according to claim 5, wherein said hue correction means limits the amount of change in hue to a predetermined value or less. 11. A color space represented by hue, saturation and lightness is represented by a hexagonal pyramid color model.
0. The image processing device according to any one of claims 1 to 7. 12. A step of enhancing a saturation edge of the image data, a step of enhancing a lightness edge of the image data, and the step of edge enhancement based on the saturation of the image data before edge enhancement. And a computer-readable recording medium storing an image processing program for causing a computer to execute the steps of correcting the saturation of image data. 13. A step of extracting a hue from image data in which each pixel value is represented by predetermined coordinates; a step of extracting saturation from the image data; And converting the image data with the edge enhanced to image data represented by hue, saturation and lightness, and correcting the hue after the edge enhancement based on the hue before the edge enhancement. A computer-readable recording medium on which an image processing program for causing a computer to execute a step and a step of correcting saturation after edge enhancement based on saturation before edge enhancement is provided. 14. A computer, comprising: enhancing a saturation edge of image data; enhancing a lightness edge of the image data; and edge enhancement based on the saturation of the image data before edge enhancement. Correcting the saturation of the image data later. 15. A computer comprising: a step of extracting hue from image data in which each pixel value is represented by predetermined coordinates; a step of extracting saturation from the image data; Emphasizing each color component; converting the image data in which the edge is enhanced into image data represented by hue, saturation, and brightness; and performing hue after edge enhancement based on the hue before edge enhancement. And correcting the saturation after the edge enhancement based on the saturation before the edge enhancement.