JP4934839B2 - Image processing apparatus, method thereof, and program - Google Patents

Description

  The present invention relates to an image processing apparatus, a method thereof, and a program.

  The color sharpness of a false color pixel composed of a pixel that should not be originally included in a digitized image signal obtained from an imaging system including an imaging element and an accompanying analog circuit and an A / D converter. As a method for reducing the color difference information, it has been proposed to acquire a high-frequency signal of an image, perform false color pixel determination of a pixel close to the acquired high-frequency signal, and then perform a smoothing process on the color difference information. Yes.

For example, in Japanese Patent Laid-Open No. 2002-262299, an edge region having a large luminance difference is detected using an edge detection filter or the like, and the color difference (Cb, Cr) of a pixel adjacent to the edge region is in an arbitrary range. The false color pixel is detected by determining whether or not, edge information including the edge gradient magnitude and the edge gradient direction of the detected edge region is calculated, and smoothness set in advance based on the calculated edge information is calculated. A method of reducing false colors by performing smoothing using a conversion filter is disclosed.
JP 2002-262299 A

  As described above, in the false color reduction method disclosed in Patent Document 1, the false color is reduced by detecting the edge direction and performing the smoothing process along the edge direction. However, this method has a problem that the corner of the edge is rounded and the color is darkened. This problem is not limited to the method of performing the smoothing process along the edge direction described above. For example, this problem also occurs when the smoothing process is performed in the same direction in the edge region.

  The present invention has been made to solve the above-described problems, and eliminates the negative effect of darkening of colors, while maintaining the color sharpness while preventing false colors generated near edges, in particular, near diagonal edges. An object of the present invention is to provide an image processing apparatus, method and program that can be reduced.

In order to solve the above problems, the present invention employs the following means.
According to a first aspect of the present invention, a false color reduction region is specified using any one of a plurality of color component images constituting a color image, and the specified false color reduction region is false. An image processing apparatus that performs color reduction processing, and determines whether or not the periphery of the target pixel is an area where edges intersect by using pixel values of peripheral pixels positioned around the target pixel of the color component image A structure determination unit that performs structure determination and identifies the area around the target pixel as an excluded area to be excluded from the false color reduction area when it is determined that the area around the target pixel intersects an edge; In this area, the image processing includes a high-frequency acquisition unit that detects an edge region in a diagonal direction, and a false color reduction region specification unit that specifies a false color reduction region from the edge region in the diagonal direction detected by the high-frequency acquisition unit Dress It is.

A second aspect of the present invention is an image processing apparatus that specifies a false color reduction region using a plurality of color component images constituting a color image and performs false color reduction processing on the specified false color reduction region. A first region specifying unit that specifies a candidate region for a false color reduction region using at least one color component image among a plurality of color component images forming a color image, and a plurality of colors forming the color image Among the color component images, using at least one color component image, a second region specifying unit that specifies a candidate region of a false color reduction region from the color information, and the false color specified by the first region specifying unit and the candidate region of the reduction region, and a second region candidate region of the false color reduction region specified by the specifying unit, provided with a false color reduction region determining unit for determining a false color reduction region, the first region The specific unit is a pixel of interest of the color component image Using the pixel values of peripheral pixels located in the periphery, a structure determination is performed to determine whether or not the periphery of the target pixel is an area where edges intersect, and it is determined that the periphery of the target pixel is an area where edges intersect And a structure determination unit that identifies the periphery of the target pixel as an excluded region excluded from the false color reduction region candidate region, and a high-frequency acquisition unit that detects an edge region in an oblique direction in a region other than the excluded region And a first false color reduction region specifying unit that specifies a candidate region of the false color reduction region from the oblique edge region detected by the high frequency acquisition unit .

According to a third aspect of the present invention, a false color reduction region is specified using any one of a plurality of color component images constituting a color image, and the specified false color reduction region is false. An image processing method for performing color reduction processing, wherein pixel values of peripheral pixels located around a pixel of interest in the color component image are used to determine whether the periphery of the pixel of interest is an area where edges intersect. A process of performing structure determination and specifying the area around the target pixel as an excluded area to be excluded from the false color reduction area when it is determined that the area around the target pixel is an intersecting edge; and an area other than the excluded area The image processing method includes a step of detecting an edge region in an oblique direction and a step of specifying a false color reduction region from the detected edge region in the oblique direction.

A fourth aspect of the present invention is an image processing method for specifying a false color reduction area using a plurality of color component images constituting a color image and performing a false color reduction process on the specified false color reduction area. The process of specifying the first candidate area of the false color reduction area using at least one color component image among the plurality of color component images constituting the color image, and the plurality of colors constituting the color image Of the component images, at least one color component image is used to identify the second candidate area of the false color reduction area from the color information, and from the first candidate area and the second candidate area A step of determining a false color reduction region, and the step of specifying the first candidate region uses the pixel values of peripheral pixels located around the pixel of interest of the color component image, Determine whether the periphery is an area where edges intersect Performing a structure determination, and when the periphery of the target pixel is determined to be an area where edges intersect, identifying the periphery of the target pixel as an excluded area to be excluded from the candidate area of the false color reduction area; and the exclusion This is an image processing method including a process of detecting an edge area in an oblique direction in an area other than the area and a process of specifying a first candidate area of a false color reduction area from the detected edge area in the oblique direction .

According to a fifth aspect of the present invention, a false color reduction region is specified using any one of a plurality of color component images constituting a color image, and the specified false color reduction region is false. An image processing program for performing color reduction processing , wherein whether or not the periphery of the target pixel is an area where edges intersect by using pixel values of peripheral pixels located around the target pixel of the color component image A process for determining a structure to determine, and when the periphery of the target pixel is determined to be an area where edges intersect, a process of specifying the periphery of the target pixel as an excluded area to be excluded from the false color reduction area; An image processing program for causing a computer to execute processing for detecting an edge region in an oblique direction and processing for specifying a false color reduction region from the detected edge region in the oblique direction.

According to a sixth aspect of the present invention, there is provided image processing for specifying a false color reduction area using a plurality of color component images constituting a color image and performing false color reduction processing on the specified false color reduction area A program that uses a pixel value of a peripheral pixel located around a target pixel of at least one color component image among a plurality of color component images constituting a color image, and edges around the target pixel intersect Exclusion is performed to determine whether or not the region is a region, and when it is determined that the periphery of the pixel of interest is a region where edges intersect, excluding the region of the pixel of interest from the candidate region of the false color reduction region A process for specifying as an area, a process for detecting an edge area in a diagonal direction in an area other than the exclusion area, and a process for specifying a first candidate area for a false color reduction area from the detected edge area in the diagonal direction Among the plurality of color component images constituting the color image, using at least one color component image, a process of identifying a second candidate region of a false color reduction region from the color information, and the first candidate region An image processing program for causing a computer to execute a process of determining a false color reduction area from the second candidate area .

  According to the present invention, it is possible to eliminate the adverse effect of darkening of color and to reduce false colors generated near edges, particularly near edges in an oblique direction, while maintaining color sharpness.

  Hereinafter, embodiments of an image processing apparatus, method, and program according to the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 is a block diagram showing the overall configuration of the imaging system according to the first embodiment of the present invention. As shown in FIG. 1, the imaging system 1 according to the present embodiment includes an imaging unit 2 and an image processing device 3.

  The imaging unit 2 includes a lens system (not shown), an IR cut filter, an optical low-pass filter, an RGB primary color single-plate image sensor (for example, a CCD, a CMOS, and the like). In the imaging unit 2, the light imaged on the single-plate imaging device through the lens system, the IR cut filter, and the optical low-pass filter is photoelectrically converted to generate an analog image signal. The analog image signal is transferred to the image processing device 3.

  The image processing apparatus 3 includes, for example, an ASIC, an analog / digital conversion unit (hereinafter referred to as “A / D conversion unit”) 101, a signal processing unit 102, an interpolation processing unit 103, a false color reduction unit 104, an edge enhancement. The image processing apparatus includes a unit 105, an image quality adjustment unit 106, an addition unit 107, a noise reduction unit 108, a compression recording unit 109, an imaging control unit 110, and the like as main components. Further, the image processing apparatus 3 includes a power switch, a shutter button, an external I / F unit (not shown) having an interface for switching various modes at the time of shooting, an output unit (not shown), and the like. Yes.

  The A / D converter 101 converts an analog image signal into a digital image signal and outputs the digital signal. Here, since the imaging system according to the present embodiment assumes an RGB primary color single-plate imaging device, the A / D converter 101 receives Rs (red), Gs (green), and Bs (blue). Each color component image is output.

  Each color component image output from the A / D conversion unit 101 is transferred to the signal processing unit 102. The signal processing unit 102 performs known signal processing such as optical black processing and white balance processing on the Rs, Gs, and Bs color component images, and outputs the processed color component images to the interpolation processing unit 103.

As shown in FIG. 2, for example, the interpolation processing unit 103 includes a high-frequency generation unit 201, an RGB generation unit 202, a color difference LPF unit 203, a horizontal / vertical false color reduction unit 204, and the like as main components.
The RGB generation unit 202 of the interpolation processing unit 103 compensates for the missing color component for each pixel of each color component image of Rs, Bs, and Gs, so that RGB (red, green, blue) ) Are interpolated, and the interpolated color component image is output to the color difference LPF unit 203. The color difference LPF unit 203 smoothes the color difference of each color component image and outputs the result to the horizontal / vertical false color reduction unit 204. The horizontal / vertical false color reduction unit 204 uses the green component image to reduce false colors generated near edges in the horizontal / vertical direction of the red component image and blue component image, and falsely displays each color component image after the false color reduction process. It outputs to the color reduction part 104 (refer FIG. 1). Further, the interpolation processing unit 103 generates a high-frequency signal YH for edge enhancement from the input Rs, Bs, and Gs color component images, and outputs the high-frequency signal YH to the edge enhancement unit 105.

  In the false color reduction unit 104, among the RGB color component images input from the interpolation processing unit 103, in particular, false colors generated near edges in the diagonal direction with respect to the pixel arrangement direction are reduced, and each processed color component is reduced. The image is output to the image quality adjustment unit 106. Here, the false color reduction unit 104 is a characteristic part of the present invention, and details thereof will be described later.

  The edge enhancement unit 105 obtains a high frequency signal YH ′ by performing a predetermined enhancement process on the high frequency signal YH input from the interpolation processing unit 103, and outputs the high frequency signal YH ′ to the addition unit 107.

  As shown in FIG. 3, the image quality adjustment unit 106 includes a color matrix processing unit 401, gamma correction units 402, 403, and 404, and a signal conversion processing unit 405 as main components. In the image quality adjustment unit 106, the color matrix processing unit 401 converts each color component image expressed in the RBG color space output from the false color reduction unit 104 into a predetermined color space such as sRBG and outputs the image. The converted component images are output to the γ correction units 402, 403, and 404, and bit conversion is performed for each color. For example, a 12-bit signal is converted into an 8-bit signal. The Rγ, Gγ, and Bγ color component images after γ correction are output to the signal conversion processing unit 405. The signal conversion processing unit 405 converts each color component image of RγGγBγ into each component image represented in the YCbCr color space by using the following expression, and outputs the converted component image.

Y = 0.299R + 0.587G + 0.114B (0 ≦ Y ≦ 255)
Cb = −0.169R−0.331G + 0.500B (−128 ≦ Cb ≦ 127)
Cr = 0.500R−0.419G−0.081B (−128 ≦ Cr ≦ 127)

  The Y component image output from the image quality adjustment unit 106 is added to the high frequency signal YH ′ output from the edge enhancement unit 105 in the addition unit 107, and the Y ′ component image after the addition is output to the noise reduction unit 108. On the other hand, the Cb and Cr component images output from the image quality adjustment unit 106 are output to the noise reduction unit 108 as they are.

The noise reduction unit 108 reduces random noise, spike noise, and the like caused by the color imaging system from the input YCbCr component images, and outputs the reduced YCbCr component images to the compression recording unit 109.
The compression recording unit 109 compresses each YCbCr component image input from the noise reduction unit 107 and records it on a predetermined recording medium such as a flash memory, a hard disk, or a magnetic tape.

  Next, the false color reduction unit 104, which is a characteristic part of the present invention, will be described in detail with reference to the drawings. FIG. 4 is a block diagram illustrating a schematic configuration of the false color reduction unit 104. As shown in FIG. 4, the false color reduction unit 104 determines the structure around the target pixel using pixel values of peripheral pixels located around the target pixel of the green component image, and excludes it from the false color reduction region. The structure determination unit 303 that identifies the exclusion region to be detected, the high-frequency acquisition unit 304 that detects the edge region in the oblique direction in the region other than the exclusion region, and the false edge reduction of the edge region in the oblique direction identified by the high-frequency acquisition unit 304 A first false color reduction area specifying part (false color reduction area specifying part) 307 specified as an area is provided as a main configuration. Furthermore, the false color reduction unit 104 includes a color difference generation unit 302, an edge direction determination unit 309, a color smoothing unit 310, an RGB generation unit 311, and the like.

Each color component image of RGB is input to the color difference generation unit 302. The color difference generation unit 302 calculates the R (red) -G (green) color difference component and the B (blue) -G (green) color difference component, and outputs the calculation result to the color smoothing unit 310.
The green component image output from the interpolation processing unit 103 is input to the structure determination unit 303 and the high frequency acquisition unit 304. The structure determination unit 303 obtains a structure determination value thr for each pixel of the green component image input from the interpolation processing unit 103. For example, as shown in FIG. 5A, if the target pixel is a0, and the four peripheral pixels positioned in the oblique direction with the target pixel a0 as the center are a1, a2, a3, and a4, the structure determination value of the target pixel a0. thr is obtained by the following equation (1).

  thr = || a1-a4 |-| a2-a3 || (1)

  Here, a1 and a4 and a2 and a3 are located on the diagonal line with the target pixel in between. For example, when the target pixel a0 and the peripheral pixels a1 to a4 have pixel values as shown in FIG. 5B, the structure determination value thr at the target pixel a0 takes a large value, for example, FIG. When the pixel value as shown in (c) has, the structure determination value thr takes a small value. The region where the structure determination value is large corresponds to, for example, each pixel belonging to the oblique edge region represented by the region B in FIG. 6, and the region where the structure determination value is small is, for example, FIG. 6 corresponds to each pixel belonging to a region where edges intersect, such as region A.

Here, the region where the edges intersect as shown by region A in FIG. 6 becomes unstable when smoothing in the same direction or in a single direction along the edge direction, and the corners are rounded to make the color black. It can cause misunderstanding. Therefore, the structure determination unit 303 detects such an area as an excluded area and excludes it from the false color reduction area. Therefore, for example, the structure determination unit 303 compares the structure determination value thr calculated for each pixel with a predetermined value slantTH set in advance, and excludes pixels having a structure determination value thr smaller than the predetermined value slantTH. Specify as an area. The flag is set to 0 for the pixel specified as the excluded area, and the flag is set to 1 for the area other than the excluded area.
This flag indicates whether the high-frequency signal acquisition unit 304 in the subsequent stage acquires a high-frequency signal, that is, whether to perform edge detection processing. In the case of flag 1, the high-frequency signal is acquired. In the case of flag 0, it indicates that a high-frequency signal is not acquired.

  The high frequency acquisition unit 304 has a band pass filter. FIGS. 7A and 7B show an example of a band-pass filter held by the high-frequency acquisition unit 304. FIG. The bandpass filter only needs to have a frequency characteristic for acquiring an edge in an oblique direction, and the coefficients and the filter size are not limited to the filters shown in FIGS. For example, an edge detection filter such as a Gradient, Laplacian, Prewitt, or Sobel operator that detects an edge region based on a differential value of a pixel may be used, or an edge based on a value that evaluates a variance between a target pixel and surrounding pixels. An area may be detected.

  The high frequency acquisition unit 304 determines the state of the flag given to each pixel input from the structure determination unit 303. As a result, if the flag is 1, a high-frequency signal is obtained using a bandpass filter. On the other hand, when the flag is 0, the high-frequency signal at the pixel position is set to 0. Further, the high frequency acquisition unit 304 changes (clips) the high frequency signal to 0 when the high frequency signal obtained using the bandpass filter is negative. As a result, a high-frequency signal is detected for a pixel position where the flag given to each pixel input from the structure determination unit 303 is 1, and a high-frequency signal is output for a pixel whose value of the high-frequency signal is negative. Set to zero. In addition, for a pixel position where the flag given to each pixel input from the structure determination unit 303 is 0, the high-frequency signal at that pixel position is set to 0. The high-frequency signal after the filtering process is output to the first false color reduction area specifying unit 307.

  The first false color reduction region specifying unit 307 determines whether or not the high-frequency signal at each pixel position is greater than or equal to a predetermined value in the high-frequency signal from the high-frequency acquisition unit 304, for example, greater than 0. If it is 0, it is determined as a non-false color reduction region, and if the high frequency signal is greater than 0, it is determined as a false color reduction region. This determination result is output to the color smoothing unit 310.

  The edge direction determination unit 309 calculates the difference between the target pixel and its surrounding pixels in a plurality of directions in the color component image from the high frequency acquisition unit 304, determines the direction with the smallest difference as the edge direction, The direction is output to the color smoothing unit 310. Specifically, in the example illustrated in FIG. 8, the edge direction determination unit 309 calculates a difference with respect to eight directions of e0 to e7 using the following formula, and the difference is the smallest value among e0 to e7. It is determined that there is an edge in the direction, and the edge direction is output to the color smoothing unit 310. In FIG. 8, Y22 is set as a target pixel, and a 5 × 5 pixel range is set as a peripheral pixel around the target pixel.

e0 = | Y22-Y23 | + | Y22-Y24 | + | Y22-Y21 | + | Y22-Y20 |
e1 = | Y22-Y23 | + | Y22-Y14 | + | Y22-Y21 | + | Y22-Y30 |
e2 = | Y22-Y13 | + | Y22-Y04 | + | Y22-Y31 | + | Y22-Y40 |
e3 = | Y22-Y12 | + | Y22-Y03 | + | Y22-Y32 | + | Y22-Y41 |
e4 = | Y22-Y12 | + | Y22-Y02 | + | Y22-Y32 | + | Y22-Y42 |
e5 = | Y22-Y12 | + | Y22-Y01 | + | Y22-Y32 | + | Y22-Y43 |
e6 = | Y22-Y11 | + | Y22-Y00 | + | Y22-Y33 | + | Y22-Y44 |
e7 = | Y22-Y31 | + | Y22-Y10 | + | Y22-Y23 | + | Y22-Y34 |

  In FIG. 8, the edge direction is determined for the eight directions using the 5 × 5 pixel range in the vicinity of the target pixel as the peripheral pixel, but the peripheral pixel range can be arbitrarily set. In order to improve the discrimination accuracy of the edge direction, it may be discriminated in the range of 7 × 7 pixels or 9 × 9 pixels, or the edge direction is set to 16 directions and discriminated as the range is expanded. It is also possible.

  The color smoothing unit 310 receives the RG color difference component and the BG color difference component from the color difference generation unit 302 and information on the false color reduction region from the first false color reduction region specifying unit 307. The color smoothing unit 310 extracts the RG color difference component and the BG color difference component of the pixels belonging to the area determined to be the false color reduction area by the first false color reduction area specifying unit 307, and extracts these color differences. Color smoothing processing is performed on the component by performing arithmetic averaging or weighted averaging processing along the edge direction (single direction) determined by the edge direction determination unit 309, and the result is sent to the RGB generation unit 311. Output. Here, it is preferable that the range in which the arithmetic average or weighted average processing is performed is processed with the same size as the range of the peripheral pixels whose edge direction is determined by the edge direction determination unit 309.

  The RGB generation unit 311 adds the green color component input from the interpolation processing unit 102 to the RG color difference component and the BG color difference component input from the color smoothing unit 310, thereby obtaining an RGB color component image. Is output to the image quality adjustment unit 105.

  In the false color reduction unit 104 having such a configuration, the structure determination by the structure determination unit 303 is performed based on the green component image, and thus an area that causes adverse effects such as darkening when false color reduction processing is performed, For example, a region where edges intersect or the like is specified as an excluded region, and the subsequent high frequency acquisition unit 304 performs a high frequency acquisition process using a bandpass filter on a region other than the excluded region. Is set to 0, and the processed high-frequency signal is output to the first false color reduction area specifying unit 307. The first false color reduction area specifying unit 307 compares the high-frequency signal at each pixel position with a predetermined value set in advance, and falsely determines an area having a predetermined value or more (or a value larger than the predetermined value). The color reduction area is determined, and the result is output to the color smoothing unit 311. On the other hand, the edge direction determination unit 309 detects the edge direction based on the high frequency signal output from the high frequency acquisition unit 304, and outputs information on the edge direction to the color smoothing unit 310.

  In the color smoothing unit 310, the edge direction discrimination unit 309 is applied to the RG color difference component and the BG color difference component corresponding to the region specified as the false color reduction region by the first false color reduction region specifying unit 307. By performing the arithmetic average or weighted average processing based on the edge direction acquired from the above, false color reduction processing is performed, and the processed color difference component is output to the RGB generation unit 311. In the RGB generation unit 311, RGB color component images are generated based on the color difference component and the green color component after the false color reduction process, and are output to the image quality adjustment unit 105.

  As described above, according to the image processing apparatus and the image processing method according to the present embodiment, an area where darkening occurs when the false color reduction process is performed, for example, the edges intersect. Area is excluded from the target area of the false color reduction process, and the false color reduction process is performed only on the area where blackening does not occur, for example, only on the oblique edge area. Can be reduced.

[Second Embodiment]
Next, an image processing apparatus and an image processing method according to the second embodiment of the present invention will be described. As shown in FIG. 9, the image processing apparatus according to the present embodiment is the first embodiment described above in that a false color reduction unit 104A is provided with a stabilization unit 306 after the high frequency acquisition unit 304. This is different from the image processing apparatus according to FIG.
Hereinafter, in this embodiment, description of points that are common to the first embodiment will be omitted, and different points will be mainly described.

  In the image processing apparatus according to the present embodiment, the high-frequency signal after the filtering process is performed by the high-frequency acquisition unit 304 of the false color reduction unit 104A is output to the stabilization unit 306. The stabilization unit 306 has, for example, a low-pass filter having a frequency characteristic that limits the vicinity of the Nyquist frequency, and performs filtering processing on the input high-frequency signal using the low-pass filter. FIG. 10 shows an example of the low-pass filter held by the stabilization unit 306. The coefficients and filter sizes of the low-pass filter shown in FIG. 10 are examples, and are not limited to this example.

  Here, as shown in FIG. 11, many false colors occur near the outside of the edge. Further, when moire is mixed in the green component image from which the high-frequency signal is acquired, the edge direction determination accuracy in the edge direction determination unit 309 in the subsequent stage is lowered, and the processing becomes unstable. Therefore, in the present embodiment, a stabilization unit 306 is provided before the edge direction determination unit 309 to improve the accuracy of edge direction determination in the edge direction determination unit 309. In addition, a stabilization unit 306 is provided in front of the first false color reduction region specifying unit 307 so that the outside of the edge where false colors are likely to occur is included in the false color reduction region.

  As described above, according to the image processing apparatus and the image processing method according to the present embodiment, the false color reduction unit 104A has low-pass filtering before the edge direction determination unit 309 and the first false color reduction region specifying unit 307. Since the stabilizing unit 306 for performing the above is provided, the outer region of the edge can be included in the false color reduction region. As a result, it is possible to improve the accuracy of edge direction discrimination and the like, and it is possible to more appropriately specify the region where the false color is generated. As a result, the accuracy of the false color reduction process can be improved, and a higher quality image can be acquired.

[Third Embodiment]
Next, an image processing apparatus and an image processing method according to the third embodiment of the present invention will be described.
In the first embodiment and the second embodiment described above, the false color reduction area is specified only based on the image structure information. However, in this embodiment, in addition to the image structure information, the color Considering the information, the false color reduction region is specified from both the structure information and the color information. Hereinafter, description of parts common to the above-described embodiments will be omitted, and different parts will be mainly described.

  FIG. 12 is a block diagram illustrating a configuration example of the false color reduction unit 104B in the image processing apparatus according to the present embodiment. As illustrated in FIG. 12, the false color reduction unit 104B according to the present embodiment uses a green component image among a plurality of color component images constituting an RGB color image and uses the structure information to identify false color reduction region candidates. Using a first component specifying unit 5 that specifies a region and a red component image and a blue component image among a plurality of color component images constituting a color image, a candidate region for a false color reduction region is specified from the color information. False color reduction from the second region specifying unit 6, the false color reduction region candidate region specified by the first region specifying unit 5, and the false color reduction region candidate region specified by the second region specifying unit 6 A false color reduction area determination unit 308 that determines an area is provided as a main component. Furthermore, the false color reduction unit 104B includes a color difference generation unit 302, an edge direction determination unit 309, a color smoothing unit 310, an RGB generation unit 311, and the like.

The first region specifying unit 5 includes a structure determination unit 303, a high frequency acquisition unit 304, a stabilization unit 306, and a first false color reduction region specifying unit 307. The second area specifying unit 6 includes a false color index calculating unit 301 and a second false color reduction area specifying unit 305.
In the first region specifying unit 5, each component is as described above, but the false color reduction region specified in the first false color reduction region specifying unit 307 in the third embodiment described above is the same in this embodiment. Is output to the false color reduction area determination unit 308 as a candidate area for the false color reduction area.

In the second area specifying unit 6, the false color index calculation unit 301 calculates the absolute value | R−B | of the R (red) -B (blue) color difference component from the blue component image and the red component image as a false color index. And output to the second false color reduction area specifying unit 305.
The second false color reduction area specifying unit 305 specifies an area in which the false color index calculated by the false color index calculation unit 301 is smaller than a predetermined value as a candidate area for the false color reduction area. For example, many false colors that occur near the edges in the diagonal direction are green and magenta. When green and magenta are expressed in RGB, they are green (0, 255, 0) and magenta (255, 0, 255), both of which have a small absolute value of BR. Therefore, when the absolute value of BR of the target pixel is small, it can be determined that the target pixel has a high possibility of false color. Therefore, in order to specify such a false color reduction area as a candidate area for the false color reduction area, the second false color reduction area specifying unit 305 determines the absolute value of the BR color difference component input from the false color index calculation unit 301. The value | R−B | is compared with a predetermined value RmBTH, and when the absolute value | R−B | is smaller than the predetermined value RmBTH, this region is specified as a candidate region for the false color reduction region, and information on the region Is output to the false color reduction area determination unit 308. The predetermined value RmBTH can be arbitrarily set.

  The false color reduction area determination unit 308 determines an area identified as a false color reduction area candidate area by both the first false color reduction area specification unit 307 and the second false color reduction area specification unit 305. And the information is output to the color smoothing unit 310. The subsequent processing is the same as in the first embodiment described above.

  In this way, by determining not only the image structure information but also the color information and determining the false color reduction region, the first false color among the regions in which darkening occurs due to the false color reduction process is performed. Even a region that cannot be removed by the reduced region specifying unit 307 can be excluded from a target region for color reduction processing. For example, by determining the false color reduction area based on the color information, an area in the vicinity of an acute edge as represented by the area C in FIG. 13 can be set as an exclusion area, resulting from the false color reduction process. It is possible to further prevent the occurrence of darkening in the area.

  In each of the above-described embodiments, the false color reduction units 104, 104A, and 104B are premised on processing by hardware, but are not necessarily limited to such a configuration. For example, a configuration in which processing is performed separately by software is also possible. In this case, the false color reduction units 104, 104A, and 104B include a main storage device such as a CPU and a RAM, and a computer-readable recording medium on which a program for realizing all or part of the above processing is recorded. . Then, the CPU reads out a program (image processing program) recorded in the storage medium and executes information processing / calculation processing, thereby realizing processing similar to that of the false color reduction unit 104 described above.

  Here, the computer-readable recording medium means a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. Alternatively, the computer program may be distributed to the computer via a communication line, and the computer that has received the distribution may execute the program.

  Hereinafter, among the image processing methods realized by the CPU executing the image processing program, the processing procedure of the false color reduction processing will be described with reference to FIG. Here, the processing procedure of the noise reduction part 104B (refer FIG. 12) which concerns on 3rd Embodiment among each embodiment mentioned above is demonstrated.

  First, color difference components (RG, BG) are obtained based on red (R), blue (G), and green (B) color component images obtained by interpolating missing pixels (step S1000 in FIG. 14). Subsequently, the absolute value | R−B | of the RB color difference component is calculated (step S1001). Next, for the green component image, a structure determination value thr is obtained based on pixel values of surrounding pixels located around the pixel of interest, and is compared with a predetermined value slantTH that is set in advance to specify an exclusion region. (Step S1002).

  Next, a high-frequency signal is obtained by performing a filtering process using a bandpass filter on a region (other than the excluded region) that is not specified as an excluded region in step S1002, and the value of the high-frequency signal is a negative number. If there is, it is clipped with 0 (step S1003). On the other hand, regarding the area specified as the excluded area in step S1002, the pixel value is set to zero without performing the filtering process (step S1004).

  In subsequent step S1005, smoothing processing is performed on the high-frequency signal obtained in step S1003 in order to stably perform edge direction discrimination and to expand the range of false color reduction to the outside. In step S1006, edge direction determination is performed with reference to peripheral pixels of the high-frequency signal smoothed in step S1005. In subsequent step S1007, it is determined whether or not the value of the high-frequency signal smoothed in step S1005 is equal to or greater than a predetermined value (for example, whether or not it is greater than 0), and is equal to or greater than the predetermined value. In this case, the absolute value | R−B | of the RB color difference component obtained in step S1001 is compared with an arbitrary threshold value RmBTH (step S1008).

  In step S1008, if the absolute value | R−B | of the RB color difference component obtained in step S1001 is smaller than the predetermined value RmBTH, the RG color difference component and BG obtained in step S1000 are determined. A false color reduction process is performed on the color difference components by performing a smoothing process in a single direction along the edge direction determined in step S1006 (step S1009). In subsequent step S1010, each of RGB color component images is generated by adding the green component image in which the missing pixel is complemented to the RG color difference component and the BG color difference component after the false color reduction processing in step S1009. .

  On the other hand, when the value of the high frequency signal smoothed in step S1005 is smaller than a predetermined value in step S1007, or in step S1008, the absolute value | RB of the RB color difference component obtained in step S1001. Is equal to or greater than the predetermined value RmBTH, the process proceeds to step S1010 without performing false color reduction processing for the pixel, and RGB color component images are generated. Then, the above-described series of processing is repeated for each pixel, and when the processing is executed for all the pixels, this processing ends.

  The processing procedure relating to the image processing method and the image processing program of the present invention is not limited to the above processing flow. In other words, it is only necessary to determine the false color reduction area from both the false color reduction area candidate area specified from the structure information and the false color reduction area candidate area specified from the color information. Is not affected.

[Fourth Embodiment]
Next, an image processing apparatus and an image processing method according to the fourth embodiment of the present invention will be described. As shown in FIG. 15, the image processing apparatus according to the above embodiment includes a false color reduction region specifying unit 507 instead of the false color reduction unit described above, and the false color reduction region specifying unit 507 to the noise reduction unit 506. However, the image processing apparatus according to each embodiment described above is different in that a false color reduction area map is output. Further, the false color reduction area specifying unit 507 is provided in the subsequent stage of the image quality adjustment unit 106, and the image processing apparatus according to each embodiment described above in that the color space to be processed is not the RGB color space but the YCbCr color space. And different. Hereinafter, in this embodiment, description of points that are common to the first to third embodiments is omitted, and different points are mainly described.

  FIG. 16 is a block diagram illustrating a schematic configuration of the false color reduction area specifying unit 507. As illustrated in FIG. 16, the false color reduction region specifying unit 507 includes a false color index calculation unit 601, a second false color reduction region specifying unit 602, a structure determination unit 603, a high frequency acquisition unit 604, a stabilization unit 605, and a first. A false color reduction area specifying unit 606 and a false color reduction area MAP creation unit 607 are provided as main components.

The false color index calculation unit 601 includes a luminance component Y ′ obtained by adding the high frequency component YH ′ output from the edge enhancement unit 105 and the luminance component Y output from the image quality adjustment unit 106 shown in FIG. The Cb color difference component and the Cr color difference component output from the adjustment unit 504 are input.
The false color index calculation unit 601 converts each component in the YCbCr color space into each component in the RGB color space using the following equations (2) and (3).

R = Y ′ + 1.40200Cr (2)
B = Y ′ + 1.77200 Cb (3)

  Then, using the converted red component image and blue component image, the absolute value | R−B | of the RB color difference component is calculated, and the calculation result is output to the second false color reduction area specifying unit 602.

  The second false color reduction area specifying unit 602 compares the absolute value | RB | of the RB color difference component input from the false color index calculation unit 601 with a predetermined value RmBTH set in advance, and R− When the absolute value | R−B | of the B color difference component is smaller than the threshold value RmBTH, the false color reduction region candidate region is identified, and the result is output to the false color reduction region MAP creation unit 607.

  On the other hand, the structure determination unit 603 calculates the structure determination value thr ′ of the target pixel by using the luminance component Y ′ by the same calculation method as in the first embodiment described above, and sets the structure determination value thr ′ in advance. Compared with the predetermined value slantTH ′, a pixel having a structure determination value thr ′ larger than the predetermined value slantTH ′ is extracted. Then, the flag is set to 1 for the extracted pixels, and the flag is set to 0 for the pixels that are not extracted.

  The high frequency acquisition unit 604 determines the state of the flag given to each pixel input from the structure determination unit 603. If the flag is 1, the pixel value is obtained after performing a filtering process using a bandpass filter. If it is negative, it is clipped to 0, and in other cases, that is, if it is an exclusion region, the pixel value is set to 0, and the processed luminance component is output to the stabilization unit 605.

  Similar to the second embodiment described above, the stabilization unit 605 has a low-pass filter having a frequency characteristic that limits the vicinity of the Nyquist frequency, for example, and uses this low-pass filter to convert the input luminance component into the luminance component. A filtering process is performed on the image. The luminance component after the filtering process is output to the first false color reduction area specifying unit 606.

  The first false color reduction region specifying unit 606 extracts a pixel having a pixel value larger than a predetermined value from the luminance component from the stabilization unit 605, and determines this pixel as a candidate region for the false color reduction region. The determination result is output to the false color reduction area MAP creation unit 607.

  The false color reduction area MAP creation unit 607 generates a false color for an area identified as a false color reduction area candidate area by both the first false color reduction area specification unit 606 and the second false color reduction area specification unit 602. The reduction area is specified, and the other areas are specified as exclusion areas. Then, a false color reduction area MAP in which the signal value 1 is written for the pixel determined as the false color reduction area and the signal value 0 is written for the pixel determined as the exclusion area is generated and output to the noise reduction unit 506. .

  FIG. 17 is a block diagram illustrating a schematic configuration of the noise reduction unit 506. In the present embodiment, the noise reduction unit 506 employs a two-stage multi-resolution noise reduction method. In the noise reduction unit 506, the first filtering units 701 and 708 are arbitrary low-pass filters used for decomposing an input signal into a specific frequency band. The reduction processing units 702 and 709 perform downsampling to reduce the input signal to ¼. The enlargement units 703, 710, and 715 perform upsampling processing for enlarging the input signal four times.

  The second filtering units 704, 711, and 716 are low-pass filters that reduce the bandwidth of the input signal. The subtractor 705 is input to the first filtering unit 701 through the first filtering unit 701, the reduction processing unit 702, the enlargement unit 703, and the second filtering unit 704, and the image signal that has undergone predetermined processing. The difference from the image signal is calculated and output to the direction filter 706. The subtraction unit 712 also calculates a difference between the image signal input to the first filtering unit 708 and the image signal from the second filtering unit 711 and outputs the difference to the directional filter 713.

  The direction filters 706 and 713 determine the direction of the input difference signal, perform a weighted average or an arithmetic average with an arbitrary intensity derived from the neighborhood dispersion value in a single direction along the determined direction, Output to rings 707 and 714. The coring 707 and 714 performs coring processing using an arbitrary threshold value on the input signal from the directional filter.

  The adder 717 performs noise reduction processing on the high band of the input signal from the first filtering unit 701 to the coring 707 and the signal obtained by noise reduction processing on the low band of the input signal from the first filtering unit 708 to the coring 714. Are added to generate and output a noise-reduced signal Y′Cb′Cr ′.

In the noise reduction unit 506 having the above-described configuration, the Y, Cb, and Cr component images that are input signals are processed independently. Here, only when the Cb and Cr component images are processed, the false color reduction area MAP is input from the false color reduction area specifying unit 507 in parallel with Cb and Cr.
When the Cb and Cr component images are processed in the noise reduction unit 506, only the reduction processing unit 709 performs reduction processing in the same manner as the Cb and Cr component images. In other blocks, the direction filters 706 and 713 are false. No processing is performed for the color reduction area MAP. In the direction filters 706 and 713, the false color reduction area MAP at the position corresponding to the processing target pixel is referred to. When the signal value is 1: false color, the weighted average or arithmetic average performed in the direction filters 706 and 713 is performed. Increase the intensity and perform noise reduction processing.

  As a result, it is possible to execute a stronger noise reduction process than the other areas for the area specified as the false color reduction area by the false color reduction area specifying unit 507. In other words, a weak noise reduction process is performed for an area that has not been specified as a false color reduction area, for example, an area where blackening is likely to occur when the false color reduction process is performed. This makes it possible to prevent the occurrence of darkening.

  As described above, according to the image processing apparatus and the image processing method according to the present embodiment, it is possible to avoid darkening of the color and to occur near the edge in the oblique direction while maintaining the color sharpness. False colors can be reduced.

In the present embodiment, the case where the two-stage multi-resolution noise reduction method is applied to the noise reduction unit 506 has been described. However, the number of stages is not limited to two. Here, if the number of stages of multi-resolution increases, lower-band noise reduction processing can be performed, and there is an advantage that lower-band false colors can be reduced with respect to false colors.
Moreover, the noise reduction part 506 should just have the capability to smooth in the single direction along an edge, and is not restricted to the case where the multi-resolution noise reduction method mentioned above is employ | adopted.

  In the above-described embodiment, the case where each process is realized by a dedicated circuit has been described. However, as in the third embodiment described above, the process can be realized by software. Hereinafter, the processing procedure of the false color reduction area specifying unit 507 according to the present embodiment will be described with reference to FIG. FIG. 18 is a flowchart showing a processing procedure of the false color reduction area specifying unit 507 according to this embodiment.

  First, Y ′, Cb, and Cr component images represented in the YCbCr color space are converted into RGB color space image components using the above-described equations (2) and (3) (step S2000), and further , The absolute value | RB | of the RB color difference component is obtained (step S2001). Subsequently, for the luminance component Y ′, a structure determination value thr ′ is obtained using pixel values of peripheral pixels located around the pixel of interest, and compared with a predetermined value slantTH ′ to specify an exclusion region (step S2002). .

  Next, in the above step S2002, a high-frequency signal is obtained by performing a filtering process using a band-pass filter for an area that has not been specified as an excluded area, and a high-frequency signal having a negative pixel value is clipped with 0. On the other hand, regarding the area specified as the excluded area in step S2002, the pixel value is set to zero without performing the filtering process (step S2004).

  In subsequent step S2005, smoothing processing is performed on the high-frequency signal obtained in step S2003 in order to stably perform edge direction discrimination and to expand the range of false color reduction to the outside. In step S2006, whether or not the high-frequency signal smoothed in step S2005 is larger than a predetermined value (for example, 0), and the absolute value | R−B | of the RB color difference component obtained in step S2002 is predetermined. The false color area is determined by determining whether it is smaller than the value RmBTH ′. As a result, the high-frequency signal smoothed in step S2005 is larger than a predetermined value, and the absolute value | RB | of the RB color difference component obtained in step S2002 is smaller than the predetermined value RmBTH ′. In this case, 1 indicating the false color reduction area is set in the false color reduction area MAP (step S2007). On the other hand, in step S2006, the high-frequency signal smoothed in step S2005 is equal to or smaller than a predetermined value, or the absolute value | RB | of the RB color difference component obtained in step S2002 is larger than a predetermined value RmBTH ′. In the case where it is detected, 0 indicating the exclusion area is set in the false color reduction area MAP (step S2008). When the above-described series of processing is executed for all pixels, the created false color reduction area MAP is output.

  As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the specific structure is not restricted to this embodiment, The design change etc. of the range which does not deviate from the summary of this invention are included.

1 is a block diagram illustrating an overall configuration of an imaging system according to a first embodiment of the present invention. It is a block diagram which shows one structural example of the interpolation process part shown in FIG. FIG. 2 is a block diagram illustrating a configuration example of an image quality adjustment unit illustrated in FIG. 1. It is a block diagram which shows one structural example of the false color reduction part shown in FIG. It is a figure for demonstrating the structure evaluation value calculated by the structure determination part. It is a figure for demonstrating an exclusion area | region and a false color reduction area | region. It is the figure which showed an example of the band pass filter used by the high frequency acquisition part. It is a figure for demonstrating the edge direction determined by the edge direction determination part. It is a block diagram which shows the example of 1 structure of the false color reduction part with which the image processing apparatus which concerns on the 2nd Embodiment of this invention is provided. It is the figure which showed an example of the low pass filter used by the stabilization part. It is a figure for demonstrating the effect | action of a stabilization part. It is a block diagram which shows the example of 1 structure of the false color reduction part with which the image processing apparatus which concerns on the 3rd Embodiment of this invention is provided. It is a figure for demonstrating the area | region specified as an exclusion area | region, when a false color reduction area | region is judged based on color information. It is the figure which showed the processing flow of the false color reduction part with which the image processing apparatus which concerns on the 3rd Embodiment of this invention is provided. It is a block diagram which shows the whole structure of the imaging system which concerns on the 4th Embodiment of this invention. FIG. 16 is a block diagram illustrating a configuration example of a false color reduction area determination unit illustrated in FIG. 15. FIG. 16 is a block diagram illustrating a configuration example of a noise reduction unit illustrated in FIG. 15. It is the figure which showed the processing flow of the false color reduction area | region determination part with which the image processing apparatus which concerns on the 4th Embodiment of this invention is provided.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Imaging system 2 Imaging part 3 Image processing apparatus 5 1st area | region specific part 6 2nd area | region specific part 104,104A, 104B False color reduction part 301,601 False color index calculation part 302 Color difference generation part 303,603 Structure determination part 304 , 604 High-frequency acquisition unit 305, 602 Second false color reduction region specifying unit 306, 605 Stabilization unit 307, 606 First false color reduction region specifying unit 308 False color reduction region determining unit 309 Edge direction determining unit 310 Color smoothing unit 311 RGB generation unit 506 Noise reduction unit 507 False color reduction region specifying unit 607 False color reduction region MAP creation unit

Claims (18)

An image processing apparatus that specifies a false color reduction region using any one of a plurality of color component images constituting a color image, and performs false color reduction processing on the specified false color reduction region There,
Using the pixel values of peripheral pixels located around the pixel of interest in the color component image, a structure determination is performed to determine whether the periphery of the pixel of interest is an area where edges intersect, and the edge of the pixel of interest includes an edge A structure determination unit that identifies the area around the target pixel as an excluded area to be excluded from the false color reduction area when it is determined that the area intersects ;
In a region other than the exclusion region, a high-frequency acquisition unit that detects an edge region in an oblique direction;
A false color reduction region specifying unit for specifying a false color reduction region from an oblique edge region detected by the high frequency acquisition unit;
An image processing apparatus comprising:   The high-frequency acquisition unit obtains a high-frequency signal by performing a filtering process having a frequency characteristic for detecting an edge in an oblique direction with respect to an area other than the excluded area, and performs the filtering process on the excluded area The image processing apparatus according to claim 1, wherein the image processing apparatus is excluded from the false color reduction area. A high-frequency signal output from the high-frequency acquisition unit is subjected to a filtering process using a low-pass filter, and includes a stabilization unit that outputs the high-frequency signal after processing,
3. The image processing according to claim 1, wherein the false color reduction area specifying unit specifies an area in which a value of the high-frequency signal output from the stabilization unit is a predetermined value or more as a false color reduction area. apparatus. A stabilization unit that performs a filtering process using a low-pass filter on the high-frequency signal output from the high-frequency acquisition unit, and outputs the high-frequency signal after processing,
An edge direction determining unit that determines an edge direction based on an output of the stabilizing unit;
A color smoothing unit that performs a color smoothing process along the edge direction on the color difference signal of the false color reduction region;
The image processing apparatus according to claim 1, further comprising:   The false color reduction region specifying unit specifies a region where the high frequency signal output from the high frequency acquisition unit is equal to or more than a predetermined value in the oblique edge region as a false color reduction region. And an image processing apparatus according to claim 4.   When the color space for processing the color image is an RGB color space, the color component image is a green component image, and when the color space for processing the color image is a YUV or YCbCr color space, the color component image The image processing apparatus according to claim 1, wherein the image is a luminance component image.   The image processing apparatus according to claim 3, wherein the low-pass filter used by the stabilization unit is a filter having a frequency characteristic that limits the vicinity of the Nyquist frequency. An image processing apparatus that identifies a false color reduction region using a plurality of color component images constituting a color image, and performs false color reduction processing on the identified false color reduction region,
A first region specifying unit that specifies a candidate region of a false color reduction region using at least one color component image among a plurality of color component images constituting the color image;
A second region specifying unit that specifies a candidate region of a false color reduction region from the color information using at least one of the plurality of color component images constituting the color image;
A false color for determining a false color reduction region from the candidate region for the false color reduction region specified by the first region specification unit and the candidate region for the false color reduction region specified by the second region specification unit A reduction area determination unit;
Equipped with,
The first area specifying unit includes:
Using the pixel values of peripheral pixels located around the pixel of interest in the color component image, a structure determination is performed to determine whether the periphery of the pixel of interest is an area where edges intersect, and the region around the pixel of interest is an edge Is determined to be an area that intersects, the structure determination unit that identifies the area around the target pixel as an excluded area to be excluded from the candidate area of the false color reduction area,
In a region other than the exclusion region, a high-frequency acquisition unit that detects an edge region in an oblique direction;
A first false color reduction region specifying unit for specifying a candidate region of the false color reduction region from the oblique edge region detected by the high frequency acquisition unit;
An image processing apparatus comprising:   The high-frequency acquisition unit obtains a high-frequency signal by performing a filtering process having a frequency characteristic for detecting an edge in an oblique direction with respect to an area other than the excluded area, and performs the filtering process on the excluded area The image processing apparatus according to claim 8, wherein the image processing device is excluded from the false color reduction region. The first region specifying unit includes a stabilization unit that performs a filtering process using a low-pass filter on the high-frequency signal output from the high-frequency acquisition unit and outputs the processed high-frequency signal.
The first false color reduction area specifying unit specifies an area in which a value of the high-frequency signal output from the stabilization unit is a predetermined value or more as a candidate area of the false color reduction area. The image processing apparatus according to 9.   When the color space for processing the color image is an RGB color space, the color component image used by the first region specifying unit is a green component image, and the color space for processing the color image is a YUV or YCbCr color space. 11. The image processing apparatus according to claim 8, wherein the color component image used by the first region specifying unit is a luminance component image.   The image processing apparatus according to claim 10, wherein the low-pass filter used by the stabilization unit is a filter having a frequency characteristic that limits the vicinity of the Nyquist frequency. The second area specifying unit is
A false color index calculation unit that calculates the absolute value of the color difference information of any two color component images as a false color index;
The system according to any one of claims 8 to 12, further comprising a second false color reduction area specifying unit that specifies an area in which the false color index is smaller than a predetermined value set in advance as a candidate area for the false color reduction area. The image processing apparatus according to claim 1.   The image processing apparatus according to claim 13, wherein the false color index calculation unit calculates an absolute value of color difference information between a red component image and a blue component image as the false color index. An image processing method for specifying a false color reduction region using any one of a plurality of color component images constituting a color image and performing false color reduction processing on the specified false color reduction region There,
Using the pixel values of peripheral pixels located around the pixel of interest in the color component image, a structure determination is performed to determine whether the periphery of the pixel of interest is an area where edges intersect, and the edge of the pixel of interest includes an edge When it is determined that the region is an intersecting region, a process of specifying the periphery of the target pixel as an excluded region excluded from the false color reduction region ;
In a region other than the excluded region, a process of detecting an edge region in an oblique direction;
Identifying a false color reduction region from the detected edge region in the oblique direction;
An image processing method. An image processing method for specifying a false color reduction region using a plurality of color component images constituting a color image and performing a false color reduction process on the specified false color reduction region,
Identifying a first candidate area of a false color reduction area using at least one color component image among a plurality of color component images constituting a color image;
Using at least one color component image among a plurality of color component images constituting the color image, and identifying a second candidate region of the false color reduction region from the color information;
Determining a false color reduction region from the first candidate region and the second candidate region ,
Identifying the first candidate region comprises:
Using the pixel values of peripheral pixels located around the pixel of interest in the color component image, a structure determination is performed to determine whether the periphery of the pixel of interest is an area where edges intersect, and the region around the pixel of interest is an edge Is determined to be an excluded area to be excluded from the candidate area of the false color reduction area, if it is determined that the area intersects,
In a region other than the excluded region, a process of detecting an edge region in an oblique direction;
Identifying a first candidate area of the false color reduction area from the detected edge area in the oblique direction . Image processing for specifying a false color reduction region using any one of a plurality of color component images constituting a color image and performing false color reduction processing on the specified false color reduction region A program,
Using the pixel values of peripheral pixels located around the pixel of interest in the color component image, a structure determination is performed to determine whether the periphery of the pixel of interest is an area where edges intersect, and the edge of the pixel of interest includes an edge When it is determined that the region intersects, a process of specifying the periphery of the target pixel as an exclusion region excluded from the false color reduction region ;
In a region other than the excluded region, a process of detecting an edge region in an oblique direction;
An image processing program for causing a computer to execute processing for identifying a false color reduction region from the detected edge region in the oblique direction. An image processing program for specifying a false color reduction area using a plurality of color component images constituting a color image and performing a false color reduction process on the specified false color reduction area,
Whether or not the periphery of the target pixel is an area where edges intersect by using pixel values of peripheral pixels positioned around the target pixel of at least one color component image among a plurality of color component images constituting the color image A process of determining whether or not the surrounding area of the target pixel is an area where edges intersect, and specifying the area around the target pixel as an excluded area to be excluded from the candidate area of the false color reduction area When,
In a region other than the excluded region, a process of detecting an edge region in an oblique direction;
A process of identifying a first candidate area of the false color reduction area from the detected oblique edge area;
A process of specifying a second candidate area of the false color reduction area from the color information using at least one color component image among a plurality of color component images constituting the color image;
A process of determining a false color reduction region from the first candidate region and the second candidate region ;
An image processing program for causing a computer to execute.

Images