KR20130000537A - Apparatus and method of correcting purple fringing - Google Patents

Abstract

PURPOSE: A purple fringing corrector and a method thereof are provided to remove a purple fringing by performing the colorization of pixels belonging to PFR(Purple Fringing Region) by seed pixels having pure colors around a detected PFR. CONSTITUTION: A purple fringing corrector detects a PFR(Purple Fringing Region)(310). The purple fringing corrector detects a boundary region around the detected purple fringing region(320). The purple fringing corrector excludes a saturated proximity region from the detected boundary region(330). The purple fringing corrector selects a seed pixel which is not influenced by a purple fringing from the boundary region(340). The purple fringing corrector determines the pixel color of the purple fringing region by the use of the selected seed pixel color(350). [Reference numerals] (310) Detecting a purple fringing region; (320) Detecting a boundary region around the purple fringing region; (330) Excluding a saturated proximity region from the boundary region; (340) Selecting a seed pixel in a region from which the saturated proximity region is excluded; (350) Determining color of the purple fringing region using the selected seed pixel; (AA) Start; (BB) End

Description

Purple fringing correction device and method {Apparatus and method of correcting purple fringing}

The present invention relates to a method for correcting purple fringing, and more particularly, by performing colorization of pixels belonging to the purple fringing area with seed pixels having pure color near the detected purple fringing area. A purple fringe correction apparatus and method for removing gongs.

Recently, digital imaging devices used by consumers are becoming smaller and smaller, and high quality images and videos are required. Effective image processing algorithms under limited hardware conditions can be one solution to improve image quality.

Image distortion and artifacts are typically due to the characteristics of optical devices such as lenses or digital image sensors such as charge coupled devices (CCDs) and complementary metal-oxide-semiconductors (CMOS). Purple fringing is one of the color artifacts that occur in images taken with a digital camera, and purple fringing is the appearance of purple color around objects. The purple fringing region loses its color and distorts the actual color, thus degrading the picture quality. Purple fringing generally occurs near edges where pixel values rapidly change to high luminance values.

Pixels near the edge are classified as color artifacts because they have a different purple color than the original colors. Purple fringing occurs with a combination of three factors: blooming, demosaicing, and chromatic aberration. Blooming and demosaicing occur due to the characteristics of the digital image sensor CCD, while chromatic aberration occurs due to the characteristics of optical devices such as lenses.

A hardware approach can be used to suppress purple fringes, or a software approach can be used to detect and correct purple fringes that have occurred.

In general, the hardware approach is to design the optimal lens design. The software approach, on the other hand, involves post-processing in digital cameras to improve picture quality.

As a hardware approach, optical lens designs have been proposed to eliminate chromatic aberration. However, there is a problem in that a high cost is required for lens design and a method limited to chromatic aberration.

In addition, digital image processing methods have been proposed as post-processing to reduce purple fringing in digital images. Digital image processing methods generally consist of two steps: purple fringe detection and purple fringe correction. The location and color of the purple fringes are used to detect the purple fringes.

The purple fringe correction step in the prior arts thus far has limited performance compared to the purple fringe detection step.

Looking at the conventional purple fring correction method, in the purple fring correction method of Document 1 and the gradient-based method of Document 2, the color of the purple fringing area is converted into an average value of RGB colors.

In addition, the inpainting method may be one of the purple fringing correction methods. Inpainting methods have been developed to restore missing or degraded parts in an image.

Hereinafter, a purple fringe correction method in Documents 1 to 2 will be described in more detail.

The purple fringe detection method of Document 1 detects near-saturation region (NSR) and candidate region (CR). NSR is the area where the light intensity is greater than the near threshold, and CR is the area where the B value is greater than the R and G values. CR adjacent to the NSR is designated as a purple fringing region (PFR).

Document 1 proposes three purple fringing correction methods.

The first correction method is to convert the color of the PFR into a single color, for example black and white. The second correction method is to assign an average value of RGB colors to the purple fringing pixels. The third is to set the R and B values using the G values.

The gradient based method of document 2 uses NSR and CR to detect PFR. This method uses more restrictive CR conditions and additionally uses gradient information from the image. The purple fringing correction of the gradient based method is the same as the second correction method of document 1.

As described above, the conventional methods merely convert the color of the purple fringing area into a single color for the purple fringing correction. However, these conventional purple fringe correction methods have a problem that is unnatural to the human eye.

[Document 1] US 7577292 B2 (S. B. Kang) August 18, 2009.

[Document 2] B.-K. Kim and R.-H. Park, “Automatic detection and correction of purple fringing using the gradient information and desaturation,” in Proc. EUSIPCO 2008 16th European Signal Processing Conf., Paper no. 1569101556, Lausanne, Switzerland, Aug. 2008. R. C. Gonzalez and R. E. Woods, Digatal Image Processing, Third edition. Upper Saddle River, NJ: Pearson Education Inc., 2010.

Accordingly, the first problem to be solved by the present invention is purple fringes to remove purple fringes by performing colorization of pixels belonging to the purple fringes region with seed pixels having pure colors near the detected purple fringes region. It is to provide a correction method.

The second problem to be solved by the present invention is to use the seed pixels unaffected by the purple fringes around the purple fringing area to colorize the pixels belonging to the purple fringing area, thereby restoring the color closest to the original color. It is to provide a purple fringing correction device.

Further, the present invention provides a computer-readable recording medium having recorded thereon a program for executing the above method on a computer.

The present invention comprises the steps of detecting a purple fringing area to achieve the first object; Detecting a boundary area around the detected purple fringing area; Excluding a saturation approximation region from the detected boundary region; Selecting a seed pixel not affected by purple fringing from the boundary region; And determining the color of the pixel of the purple fringing area using the color of the selected seed pixel.

According to an embodiment of the present invention, the purple fringe correction method preferably uses the Yxy color space of the CIE system composed of luminance value Y, chromaticity value x, and chromaticity value y.

The determining of the color of the pixel of the purple fringing area may include determining the color of the seeding pixel by using a chromaticity value of the purple fringing area when the luminance value of the seed pixel is similar to the luminance value of the purple fringing area. You can set it similar to the value.

The cost function for the chromaticity value x or the chromaticity value y is the sum of the squared difference between the chromaticity value of the seed pixel r and the weighted average of the chromaticity values of the peripheral pixels s in the purple fringing region. The chromaticity value of which the cost function is minimized may be determined as the chromaticity value of the purple fringing area.

Further, the weighting function applied to the chromaticity values of the peripheral pixels s is preferably determined based on the square of the difference between the luminance value of the seed pixel and the luminance value of the purple fringing pixels.

According to another embodiment of the present invention, the boundary region is created by inflating the purple fringed region and then removing the purple fringed region from the expanded purple fringed region. In addition, detecting the purple fringing area may detect the purple fringing area using a chromaticity diagram based method.

In order to achieve the second object, the present invention provides a method for detecting a purple fringing area, a boundary area around the detected purple fringing area, and then excluding a saturated approximation area from the detected bordering area. Fringing detection unit; A seed pixel selector configured to select a seed pixel not affected by purple fringing from a boundary region from which the saturation approximation region is excluded; And a colorizer configured to determine a color of a pixel of the purple fringing area by using a color of the selected seed pixel.

In order to solve the above other technical problem, the present invention provides a computer readable recording medium having recorded thereon a program for executing the above-described purple fringe correction method on a computer.

According to the present invention, purple fring may be removed by colorizing pixels belonging to the PFR with seed pixels having a pure color near the detected PFR.

In addition, according to the present invention, by using seed pixels not affected by purple fringe around the PFR to colorize pixels belonging to the PFR, the color closest to the original color can be restored.

1 is a block diagram of a purple fringe correction device according to an embodiment of the present invention.
2 is a diagram illustrating selecting a seed pixel.
3 is a flowchart of a purple fringing correction method according to an exemplary embodiment of the present invention.
4 is a view showing a resultant image of an intermediate process for seed pixel selection.
5 shows the resulting images of the intermediate processes of colorization.

Prior to the description of the specific contents of the present invention, for the convenience of understanding, the outline of the solution of the problem to be solved by the present invention or the core of the technical idea will be presented first.

Purple fringe correction method according to an embodiment of the present invention comprises the steps of detecting the purple fringe area; Detecting a boundary area around the detected purple fringing area; Excluding a saturation approximation region from the detected boundary region; Selecting a seed pixel not affected by purple fringing from the boundary region; And determining the color of the pixel of the purple fringing area using the color of the selected seed pixel.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, these examples are intended to illustrate the present invention in more detail, it will be apparent to those skilled in the art that the scope of the present invention is not limited thereby.

The configuration of the invention for clarifying the solution to the problem to be solved by the present invention will be described in detail with reference to the accompanying drawings based on the preferred embodiment of the present invention, the same in the reference numerals to the components of the drawings The same reference numerals are given to the components even though they are on different drawings, and it is to be noted that in the description of the drawings, components of other drawings may be cited if necessary. In addition, in describing the operation principle of the preferred embodiment of the present invention in detail, when it is determined that the detailed description of the known function or configuration and other matters related to the present invention may unnecessarily obscure the subject matter of the present invention, The detailed description is omitted.

In addition, in the entire specification, when a part is referred to as being 'connected' to another part, it may be referred to as 'indirectly connected' not only with 'directly connected' . Also, to include an element does not exclude other elements unless specifically stated otherwise, but may also include other elements.

The present invention provides an effective purple fringing correction method using colorization in the Yxy color space. Colorization is a computerized process of adding color to a grayscale image, video, or movie. Thus, colorization provides one method for purple fringing correction.

On the other hand, a chromaticity diagram based method is used to detect the purple fringing area PFR, and the detected purple fringing area is corrected by colorization. At this time, the color of intact pixels near the purple fringing area is determined by the color of the seed pixel. Experimental results using a large number of test digital images with purple fringes show that purple fringed areas corrected by the present invention appear more natural to the observer's eye than purple fringed areas corrected by other conventional methods. .

1 is a block diagram of a purple fringe correction device according to an embodiment of the present invention.

Referring to FIG. 1, the purple fringe correcting apparatus according to the present exemplary embodiment includes a purple fringe detecting unit 100, a purple fringe correcting unit 110, and an RGB converter 140. The purple fringe correcting unit 110 includes a seed pixel selector 120 and a colorizer 130.

The purple fringe detection unit 100 detects the purple fringe area in the image.

A purple fringing region (PFR) represents a purple fringing region, and a non-purple fringing region (NPFR) represents a region that is not a purple fringing region.

The purple fringe detection unit 100 uses a chromaticity diagram based method for purple fringe detection. The chromaticity diagram based method provides more reliable and accurate detection results than other methods, but other methods that can detect purple fringing areas may be used.

Therefore, the purple fringe detection unit 100 of the present invention uses a CIE color system. The CIE color system is a device-independent system that takes into account the sensitivity and perception of the human visual system. Therefore, the Yxy color space is useful for detecting and correcting purple fringes. Since the colorization to be performed by the colorizer 130 is performed in the Yxy color space used by the purple fringe detection unit 100, no additional color space conversion is necessary.

On the other hand, the Yxy color space can be obtained from the sRGB color space.

First, the linear color values CL (CL = RL, GL, and BL) in the sRGB color space can be represented as follows.

Where C (C = R, G, and B) represents the normalized sRGB value.

Second, the conversion between CIE XYZ tristimulus values and CL can be expressed as

Here, X, Y, and Z represent CIE tristimulus values, respectively.

Finally, the two normalized chromaticity coordinates x, y in the CIE XYZ color space are defined as

Hereinafter, the chromaticity diagram-based method will be described in detail.

 In a chromaticity diagram based method, purple fringing areas are detected and corrected using a Commission International de l'Eclairage (CIE) Yxy chromaticity diagram. At this time, to correct the purple fringing, the PFR sets the chromaticity values x and y to the white point while maintaining the luminance value Y as it is.

The chromaticity diagram based method is for detecting and correcting purple fringing in the CIE Yxy chromaticity diagram. This method detects NSR using luminance value Y in the CIE Yxy color space. The CR is then selected from the color range of purple fringing in the chromaticity diagram.

Gradient information calculated in the RGB color space is used to detect the purple fringing area. At this time, a color change region (CCR) is detected in the purple fringing region.

Therefore, PFR is defined as pixels that satisfy the following condition.

Here, CR _overlapped is defined as

Here, NSR _{d − boundary} is the _boundary of the expanded NSR, and CR _k represents the CR of the k-th label. Here, K means the total number of CR.

The purple fring detection unit 100 receives an RGB value (I _RGB (r)) in the pixel r, and from this, a purple fringing area (PFR _Yxy (r)) in the Yxy color space, and a saturation approximation in the Yxy color space. The region NSR _Yxy (r) and the Yxy value I _Yxy (r) in the pixel r are transmitted to the seed pixel selector 120. In addition, the purple fringing area (PFR _Yxy (r)) in the Y _xy color space is transferred to the colorizing unit 130, and the non-purple fringing area (non-purple fringing region, NPFR _Yxy (r)) is transferred. Transfer to the RGB converter 140.

The purple fringe correcting unit 110 corrects the detected purple fringe area. Purple fringing correction is made by selecting a seed pixel to be used to determine the color of a pixel of the purple fringing area and colorizing the pixel of the purple fringing area with the selected seed pixel.

The purple fringe correcting unit 110 includes a seed pixel selector 120 and a colorizer 130.

The seed pixel selector 120 selects the seed pixel using the detected purple fringing area PFR, a boundary area around the purple fringing area PFR _{d − boundary} , and a saturation approximation area. Seed pixels are pixels with the original color where the colors are not distorted by purple fringing.

2 is a diagram illustrating selecting a seed pixel.

During the expanded PFR (PFR _dilation ), pixels except NSR are designated as seed pixels.

1 and 2, a method of selecting a seed pixel will be described in detail below.

Seed pixels are selected using morphological operations. Seed pixels should be selected with pixels whose color is not distorted by purple fringing. Thus, we use conformal arithmetic to select seed pixels. The following formal operations are performed on the PFR and NSR obtained in the detection step. Morphological calculations use the method described in Document 3.

First, expanded PFR, or PFR _dilation , is defined as

는 팽창시 구조 요소(structuring element) SE의 리플렉션이고,

는 팽창 연산자(dilation operator)이다.here,

Is the reflection of the structuring element SE upon expansion,

Is a dilation operator.

Second, the PFR is removed from the expanded PFR to extract the boundaries of the expanded PFR. This can be expressed as follows.

Third, select the seed pixel from the boundary of the expanded PFR. NSR can be defined as the area near the white point in the CIE Yxy chromaticity diagram. The pixels in the NSR have high luminance values for each color component, so there is little color information. Therefore, the pixels in the NSR are preferably excluded from the seed pixel, so that the seed pixels can be determined as follows. That is, the seed pixels are selected from the boundary of the extended PFR, and the pixels in the NSR are excluded from the seed pixel because they have a high luminance value.

In order to select the seed pixel as described above, a shape operation is used. Morphological operations are performed using PFR and NSR extracted at the detection stage. The color of the seed pixels is conveyed by colorization to the color of the purple fringed pixels.

The colorizer 130 determines the colors of the pixels in the purple fringing area by using the selected seed pixel. Colorization is a computerized process of adding color to a grayscale image, video, or movie.

By colorization the color of the seed pixels is propagated to the color of the purple fringing pixels. Colorization consists of selecting seed pixels in the Yxy color space and colorizing the pixels of the purple fringing area.

An algorithm is used that automatically propagates the color of the seed pixels to pixels without color in the image. Since the cost function is minimized under the condition that adjacent pixels with similar luminance values Y also have similar chromaticity values x and y, they belong to the purple fringing area with chromaticity values x and y with minimized cost function values. Determine the color of the pixels.

Meanwhile, the present invention uses the Yxy color space of the CIE system. The Yxy color space consists of a black and white channel (Y) and a chroma channel (x and y).

In the present invention, the cost function J (x) for the chromaticity value x is the sum of squared differences between the chromaticity value x at pixel r and the weighted average of the x values of the surrounding pixels s.

This can be expressed as follows.

Here, w (r) is a weight function, and x (r) and x (s) represent x values at pixel r and pixel s. N (r) represents peripheral pixels of pixel r.

The cost function J (y) for the chromaticity value y is calculated like the cost function J (x).

Meanwhile, the weighting function w (r) in colorization based on the square of the difference between the luminance value Y of the seed pixels and the luminance value of the purple fringing pixels can be expressed as follows.

Here, Y (r) and Y (s) represent Y values at the pixel r and the pixel s. σ _r means the standard deviation of the luminance values of the pixels in the window around pixel r. In this case, the window uses 3ⅹ3 windows.

The RGB converter 140 converts the color space of pixels in the image from the Yxy color space to the RGB color space.

3 is a flowchart of a purple fringing correction method according to an exemplary embodiment of the present invention.

Referring to FIG. 3, the purple fringe correcting method according to the present embodiment includes steps that are processed in time series in the purple fringe correcting apparatus shown in FIG. 1. Therefore, even if omitted below, the above description of the purple fringe correcting apparatus shown in FIG. 1 is also applied to the purple fringe correction method according to the present embodiment.

The present invention is made in the Yxy color space of the CIE system, in which case effective color correction is possible, based on colorization in the Yxy color space, and no additional color space conversion is necessary. The Yxy color space consists of a monochromatic channel (Y) and a chromaticity channel (x, y).

The present invention also uses morphological operations to select seed pixels with intact color of the PFR. Thereafter, the PFR is corrected to have a color value similar to that of the surrounding pixels while maintaining the luminance value.

In operation 310, the purple fringe correcting apparatus detects the purple fringe area in the image. For purple fring detection, a chromaticity diagram based method is used. The chromaticity diagram based method provides more reliable and accurate detection results than other methods, but other methods that can detect purple fringing areas may be used.

In operation 320, the purple fringe correcting apparatus detects a boundary area around the purple fringe area. The boundary region around the purple fringing region may be detected by excluding the PFR from the expanded PFR (PFR _dilation ) as shown in Equation (7).

In operation 330, the purple fringe correcting apparatus excludes the saturated approximation region from the boundary region around the purple fringe region.

The NSR may be defined as an area near a white point. Since the pixels in the NSR have a high luminance value for each color component, there is little color information. Therefore, the pixels in the NSR are preferably excluded from the seed pixel as shown in Equation (8).

In operation 340, the purple fringe correcting apparatus selects the seed pixel in the boundary region from which the saturation approximation region is excluded. Referring to Equation 8, seed pixels are selected from the boundary of the extended PFR, and pixels in the NSR are excluded from the seed pixel because they have high luminance values.

In operation 350, the purple fringe correcting apparatus determines a color of the purple fringed area using the selected seed pixel.

In this case, an algorithm is used to automatically propagate the color of the seed pixels to pixels without colors in the image. Since the cost function is minimized under the condition that adjacent pixels with similar luminance values Y also have similar chromaticity values x and y, they belong to the purple fringing area with chromaticity values x and y with minimized cost function values. Determine the color of the pixels.

4 is a view showing a resultant image of an intermediate process for seed pixel selection.

Figure 4 (a) is the original image of the building, Figure 4 (b) is a view showing the purple fring detection results. Referring to FIG. 4B, the RGB values of NPFR are set to 0 (black).

4 (c) is a diagram illustrating an NSR. Referring to FIG. 4C, the RGB values of the non-NSR region are set to zero. The pixels in the NSR have little color information. This is because the pixels in the NSR have high luminance values for each of the color components.

On the other hand, referring to Figure 4 (d), it can be seen that the seed pixels have a pure color that is not distorted by purple fringing.

5 shows the resulting images of the intermediate processes of colorization.

5 (a) is the original building image.

FIG. 5B is an enlarged view of a portion of FIG. 5A.

In FIG. 5C, the PFR is extracted from FIG. 5B, and in FIG. 5C, the RGB values of the NPFR are set to zero. Since the present invention uses the same detection algorithm as that used in the chromaticity diagram based method, the image of FIG. 5C is the same as the purple fringing detection result image of the chromaticity diagram based method. Referring to FIG. 5C, purple fringing occurs near an edge where pixel values suddenly change to a large value.

FIG. 5 (d) shows that the PFR in the image is set to grayscale from FIG. 5 (b). If the grayscale values, eg, the luminance value Y of the seed pixel and the PFR, are similar, the chromaticity values x and y are set to similar values.

Purple fringe correction results according to the present invention is shown in Figure 5 (e), Figure 5 (f) is an enlarged image of a portion of Figure 5 (e).

It can be seen that the correction region of FIG. 5F is more natural. Since this correction area is an area corrected by colorization, the color of the corrected area is not black and white but the color of the area near the detected PFR. Pixels with pure color near the detected PFR are selected as seed pixels.

Embodiments of the present invention may be implemented in the form of program instructions that can be executed by various computer means and recorded in a computer readable medium. The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. The program instructions recorded on the medium may be those specially designed and constructed for the present invention or may be available to those skilled in the art of computer software. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tape, optical media such as CD-ROMs, DVDs, and magnetic disks, such as floppy disks. Magneto-optical media, and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include not only machine code generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like. The hardware device described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

In the present invention as described above has been described by the specific embodiments, such as specific components and limited embodiments and drawings, but this is provided to help a more general understanding of the present invention, the present invention is not limited to the above embodiments. For those skilled in the art, various modifications and variations are possible from these descriptions.

Accordingly, the spirit of the present invention should not be construed as being limited to the embodiments described, and all of the equivalents or equivalents of the claims, as well as the following claims, belong to the scope of the present invention .

Claims (15)

Detecting a purple fringing area;
Detecting a boundary area around the detected purple fringing area;
Excluding a saturation approximation region from the detected boundary region;
Selecting a seed pixel not affected by purple fringing from the boundary region; And
Determining a color of a pixel of the purple fringing area using a color of the selected seed pixel. The method according to claim 1,
The purple fring correction method uses the Yxy color space of the CIE system consisting of a luminance value Y, a chromaticity value x, and a chromaticity value y. The method according to claim 1,
Determining the color of the pixels of the purple fringing area,
And when the luminance value of the seed pixel and the luminance value of the purple fringing area are similar, setting the chromaticity value of the purple fringing area to be similar to the chromaticity value of the seed pixel. The method of claim 2,
The cost function for the chromaticity value x or the chromaticity value y is determined as the sum of the squared difference between the chromaticity value at the seed pixel r and the weighted average of the chromaticity values of the surrounding pixels s in the purple fringing region. Become,
And a chromaticity value of which the cost function is minimized as a chromaticity value of the purple fringing area. 5. The method of claim 4,
And a weighting function applied to the chromaticity values of the peripheral pixels s is determined based on the square of the difference between the luminance value of the seed pixel and the luminance value of the purple fring pixels. The method according to claim 1,
And the boundary region is generated by inflating the purple fringing region and then removing the purple fringing region from the expanded purple fringing region. The method according to claim 1,
Detecting the purple fringing area
The purple fring correction method of detecting the purple fringing area using a chromaticity diagram based method. A purple fringe detection unit configured to detect a purple fringed area, detect a boundary area around the detected purple fringed area, and then exclude a saturated approximation area from the detected boundary area;
A seed pixel selector configured to select a seed pixel not affected by purple fringing from a boundary region from which the saturation approximation region is excluded; And
And a colorizer configured to determine a color of a pixel of the purple fringing area using a color of the selected seed pixel. The method of claim 8,
The purple fringe correcting apparatus uses the Yxy color space of the CIE system consisting of a luminance value Y, a chromaticity value x, and a chromaticity value y. The method of claim 8,
The coloring unit,
And when the luminance value of the seed pixel and the luminance value of the purple fringing area are similar, setting the chromaticity value of the purple fringing area to be similar to the chromaticity value of the seed pixel. 10. The method of claim 9,
The cost function for the chromaticity value x or the chromaticity value y is determined as the sum of the squared difference between the chromaticity value at the seed pixel r and the weighted average of the chromaticity values of the surrounding pixels s in the purple fringing region. Become,
The color fring correcting apparatus of claim 1, wherein the colorizing unit determines a chromaticity value of the purple fringing area as a chromaticity value of which the cost function is minimized. 12. The method of claim 11,
And a weighting function applied to the chromaticity values of the peripheral pixels s is determined based on the square of the difference between the luminance value of the seed pixel and the luminance value of the purple fringing pixels. The method of claim 8,
And the boundary region is generated by expanding the purple fringing region and then removing the purple fringing region from the expanded purple fringing region. The method of claim 8,
The purple fring detection unit
The purple fringing correction device, characterized in that for detecting the purple fringing area using a chromaticity diagram based method. A computer-readable recording medium having recorded thereon a program for executing the method of any one of claims 1 to 7.

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