JP2013197680A - Image correction device, image correction method, and computer program for image correction - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image correction device capable of reducing a noise component contained in a pixel value while suppressing an image blur due to a residual image not only for a zone where a mobile body is photographed but also the surrounding zone.SOLUTION: An image correction device 6 includes: a first pixel selection part 11 for setting a first filter zone in the surrounding of a focus pixel on a first image and selecting, from the first filter zone, a first pixel having a pixel value within a first permissible range including a predetermined reference value that is set on the basis of a value of the focus pixel; a second pixel selection part 12 for setting a second filter zone in the surrounding of a reference pixel existing at the same position as a focus pixel on at least one of second images generated before or after generating the first image and selecting, from the second filter zone, a second pixel having a pixel value within a second permissible range including the predetermined reference value; and a synthesis part 13 for establishing, as a correction value for the focus pixel, a value obtained by synthesizing the value of the first pixel with that of the second pixel.

Description

  The present invention provides, for example, an image correction apparatus, an image correction method, and an image correction that reduce noise components included in pixel values on an image to be processed using an image generated before or after the image to be processed. It relates to a computer program.

  Conventionally, using a plurality of temporally continuous images such as a moving image or a plurality of continuously shot still images, a noise component included in a pixel value of each pixel of any one of the plurality of images is obtained. Technology to reduce it is being studied. Such a technique is called 3-dimensional noise reduction (3-DNR).

  In an example of an image correction apparatus using 3DNR, a fluctuation component of the value of each pixel on the image in the time axis direction is a noise component to be removed. Therefore, the image correction apparatus reduces the noise component by temporally averaging the values of the pixels at the same position in a plurality of temporally continuous images. However, in the plurality of images, the position of the moving area in which the moving object is reflected differs for each image. Therefore, if the values of the pixels at the same position among multiple images are temporally averaged, the values of the pixels that show the moving object and the values of the pixels that do not show the moving object are averaged, especially around the boundary of the moving region. Therefore, an afterimage of the moving object is generated around the boundary, and as a result, the image is blurred.

  Thus, a technique has been proposed in which an image space filter is applied to a motion region and a spatio-temporal filter is applied to a stationary region other than the motion region (see, for example, Patent Document 1).

JP 2008-193142 A

  However, even with the above-described technique, if the subject shown in the motion region has a fine structure, the fine structure may be blurred by applying the image space filter. In addition, the boundary of the subject in the motion region is also blurred by applying the image space filter.

  Therefore, it is an object of the present specification to provide an image correction apparatus capable of reducing a noise component included in a pixel value while suppressing blurring due to an afterimage of an area where a moving object is captured and its peripheral area. .

  According to one embodiment, an image correction apparatus is provided. The image correction apparatus sets a first filter region around a target pixel on the first image, and sets a predetermined reference value set based on the value of the target pixel from the first filter region. A first pixel selecting unit that selects a first pixel having a pixel value within a first allowable range, and a target pixel on at least one second image generated before or after the first image A second filter region is set around the reference pixel at the same position as the second pixel, and a second pixel having a pixel value within a second allowable range including a predetermined reference value is selected from the second filter region. A second pixel selection unit to select; and a synthesis unit that uses a value obtained by synthesizing the value of the first pixel and the value of the second pixel as a correction value of the target pixel.

The objects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.
It should be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention as claimed.

  The image correction apparatus disclosed in this specification can reduce noise components included in pixel values while suppressing blurring due to afterimages in a region where a moving object is captured and its peripheral region.

It is a block diagram of the imaging device with which the image correction apparatus was incorporated. It is a schematic diagram which shows the outline | summary of the process performed by an image correction apparatus. It is a block diagram of the image correction apparatus by one Embodiment. (A) is a figure which shows an example of the filter range set with respect to the attention pixel of an attention image, and the pixel selected, (b) is the filter range set with respect to a reference image, and is selected. It is a figure which shows an example of a pixel. It is an operation | movement flowchart of the image correction process performed by the image correction apparatus. In a modification, it is a figure which shows an example of the order of the pixel selection with respect to a reference image. In a modification, it is a figure which shows an example of the order of the pixel selection with respect to an attention image. FIG. 10 is a configuration diagram of a computer that operates as an image correction apparatus when a computer program that realizes functions of respective units of the image correction apparatus according to an embodiment or a modification thereof is operated.

Hereinafter, an image correction apparatus according to an embodiment will be described with reference to the drawings.
The image correction apparatus corrects the value of each pixel of the target image using one or more reference images generated before or after the target image, thereby including noise included in the value of each pixel of the target image. Reduce ingredients. For this purpose, this image correction apparatus has a pixel value within a first allowable range of a pixel value determined using a value of the target pixel as a reference value from a filter region set around any target pixel set on the target image. Select a pixel with a value. Similarly, the image correction apparatus also uses a second pixel value determined from the filter region set around the reference pixel at the same position as the target pixel on each reference image. Select a pixel with a value within the allowable range. This image correction apparatus uses the value obtained by combining the values of the selected pixels as the correction value of the target pixel, so that the afterimage of the moving object is also obtained in the region where the moving object is shown and its surrounding region. It is possible to obtain the 3DNR effect while suppressing blur caused by.

In the present embodiment, the image to be processed is a color digital image that is expressed in the RGB color system and has a gradation of 8 bits for each color. The pixel value in the following description represents a specific color component. Then, the processing described below is executed for each color component.
The number of bits representing the gradation of each color component is not limited to 8 bits, and may be 4 bits or 10 bits, for example. Further, the image to be processed may be a color digital image represented by another color system such as a YUV color system or HSV color system. In this case, the pixel values in the following description represent components such as hue, saturation, and luminance. Then, the following processing is executed for each component. Alternatively, the image to be processed may be a gray image in which each pixel has only a luminance value.
Further, when the image to be processed is an image included in the moving image data, the image may be a frame generated by the progressive method or a field generated by the interlace method. .

  FIG. 1 is a schematic configuration diagram of an imaging apparatus in which an image correction apparatus according to one embodiment is incorporated. The imaging device 1 is an imaging device capable of generating a plurality of temporally continuous images, and is, for example, a video camera, a mobile phone having a moving image shooting function, or a digital camera having a moving image shooting function or a continuous shooting function. As illustrated in FIG. 1, the imaging device 1 includes a camera module 2, an operation unit 3, a display unit 4, a storage unit 5, an image correction device 6, and a control unit 7. Furthermore, the imaging device 1 may have an interface circuit (not shown) according to a serial bus standard such as a universal serial bus in order to connect the imaging device 1 to another device such as a computer or a television. The control unit 7 and other units of the imaging device 1 are connected by, for example, a bus.

  The camera module 2 includes an image sensor having an array of solid-state imaging elements arranged two-dimensionally, and an imaging optical system that forms an image of a subject on the image sensor. And the camera module 2 produces | generates the image in which the image of the to-be-photographed object was reflected with a fixed period. As described above, this image is a color digital image represented by the RGB color system and having a gradation of 8 bits for each color. The camera module 2 stores the generated image in the storage unit 5 each time an image is generated.

  The operation unit 3 includes, for example, various operation buttons or dial switches for the user to operate the imaging device 1. The operation unit 3 transmits to the control unit 7 a control signal for setting the shutter speed, the aperture diameter, or the like, or a control signal for starting shooting or focusing, in accordance with a user operation.

  The display unit 4 includes, for example, a display device such as a liquid crystal display device, and displays various types of information received from the control unit 7 or an image generated by the camera module 2. Note that the operation unit 3 and the display unit 4 may be integrally formed using, for example, a touch panel display.

  The storage unit 5 includes, for example, a readable / writable volatile or nonvolatile semiconductor memory circuit. The storage unit 5 stores the image received from the camera module 2. The storage unit 5 passes the image to the image correction device 6 in response to a read request from the image correction device 6, and the storage unit 5 receives the noise component included in the pixel value of each pixel received from the image correction device 6. The reduced corrected image is stored. Furthermore, when each function of the image correction apparatus 6 is realized by a computer program executed on a processor of the control unit 7, the computer program may be stored.

  The image correction device 6 corrects the value of each pixel of the target image to be processed using a reference image generated before or after the target image, thereby including noise included in the value of each pixel of the target image. A corrected image with reduced components is generated. Details of the image correction device 6 will be described later.

  The control unit 7 includes at least one processor and its peripheral circuits, and controls the entire imaging apparatus 1. For example, the control unit 7 sets the shutter speed or the aperture diameter according to the setting signal received from the operation unit 3 and the exposure amount of the subject. Further, the control unit 7 may adjust the color balance for the image corrected by the image correction device 6 or execute processing such as edge enhancement or contrast enhancement.

Hereinafter, an outline of processing executed by the image correction apparatus 6 will be described.
FIG. 2 is a schematic diagram showing an outline of image correction processing executed by the image correction device 6. FIG. 2 shows a target image 200 and two reference images 210 and 220 that are generated after the target image 200 and are temporally continuous. The image correction device 6 sets the value of the target pixel 201 on the target image 200 to the reference pixel 211 at the same position as the target pixel in the two reference images 210 and 220 with the values of pixels around the target pixel 201. Correction is performed using the values of pixels around 221. Therefore, the image correction apparatus 6 sets filter regions 202, 212, and 222 around the target pixel 201 and the reference pixels 211 and 221 in each image, respectively. Then, the image correction device 6 selects a pixel having a pixel value within a predetermined allowable range including the value of the target pixel as the reference value from each filter area. Here, the graph shown on the right side of each image represents a profile of pixel values in the filter region along a horizontal line X passing through the target pixel or the reference pixel. In each graph, the horizontal axis represents the pixel position in the horizontal direction. The positions of the target pixel and the reference pixel are represented by “P”. The vertical axis represents the pixel value. The pixel value allowable range 204 is indicated by a dotted line. A profile 205 is a profile of pixel values in the filter region 202 on the line X in the target image 200. Profiles 215 and 225 are profiles of pixel values in the filter region 212 or 222 on the line X in the reference images 210 and 220, respectively.

In this example, in the target image 200, a part of the moving object 203 is shown in the target pixel 201. Therefore, a pixel group 206 surrounded by a dotted line including the target pixel 201 is selected from the target image 200.
On the other hand, in the reference images 210 and 220, since the moving object 203 has moved rightward, the moving object 203 is not shown in the reference pixels 211 and 221. However, in the image correction apparatus 6, not only the reference pixels 211 and 221 located at the same position as the target pixel 201, but also included in the filter regions 212 and 222 set around the target pixel 201 and the pixel value of the target pixel 201 is used as a reference. A pixel within an allowable range set as a value is selected. Therefore, pixel groups 216 and 226 surrounded by a dotted line corresponding to pixels in which the moving object 203 is captured are selected from the reference images 210 and 220 as well. Since the image correction device 6 obtains the correction value of the target pixel 201 based on the value of the pixel selected from these three images that are temporally continuous, while preventing the afterimage of the moving object 203 from occurring, The 3DNR effect can be obtained.

Hereinafter, each component of the image correction apparatus 6 will be described. FIG. 3 shows a configuration diagram of the image correction apparatus 6. The image correction apparatus 6 includes a space-similar pixel selection unit 11, a time-similar pixel selection unit 12, and a synthesis unit 13.
These units included in the image correction apparatus 6 are formed as one integrated circuit in which circuits corresponding to the units are integrated. Each of these units included in the image correction device 6 may be formed as a separate circuit.

The spatially similar pixel selection unit 11 sequentially sets each pixel on the target image to be processed as the target pixel, and sets a predetermined filter area around the target pixel. Then, the space-similar pixel selection unit 11 selects, from the filter area, a pixel having a pixel value within a first allowable range set with the value of the target pixel as a reference value. The filter area is, for example, a rectangular area having a size of 3 vertical pixels × 3 horizontal pixels centered on the target pixel. Further, the first allowable range is a range corresponding to fluctuations in pixel values assumed from noise generated in the electronic circuit of the imaging apparatus 1 and noise due to fluctuations in the number of photons incident on the imaging elements corresponding to individual pixels, For example, when the pixel value is represented by 0 to 255, the reference value is set to ± 25.
The spatially similar pixel selection unit 11 notifies the synthesis unit 13 of information indicating the position of the pixel selected on the target image.

  The time-similar pixel selection unit 12 sets a predetermined filter region around a reference pixel at the same position as the target pixel on the target image with respect to at least one reference image generated before or after the target image. . Then, the time-similar pixel selection unit 12 selects, from the filter area, a pixel having a pixel value within the second allowable range set with the value of the target pixel as a reference value.

  The reference image is preferably an image that is continuous in the time axis direction with respect to the target image so that the second filter region includes pixels in which the same subject as the subject that is captured in the target pixel is included. However, the reference image is not limited to an image continuous in the time axis direction with respect to the target image. For example, it is assumed that the attention image is a top field including only odd-numbered rows of data among fields obtained by the interlace method. In this case, the reference image can also be a top field generated before or after the target image, not the bottom field generated immediately before or after the target image. The time-similar pixel selection unit 12 may use only an image acquired before the target image as a reference image, or may use only an image acquired after the target image as a reference image.

  The filter area set for the reference image is preferably larger than the filter area set for the target image. As a result, even if the subject shown in the pixel of interest is a moving object, there is a high possibility that the same point as the point on the subject shown in the pixel of interest is included in the filter region set on the reference image. For example, the filter area set for the reference image is a rectangular area having a size of 5 vertical pixels × 5 horizontal pixels centered on the target pixel.

  The second allowable range set for the reference image is preferably narrower than the first allowable range set for the target image. As described above, since the filter area set for the reference image is wider than the filter area for the target image, the filter area set for the reference image includes a subject different from the subject shown in the target pixel. There are also many pixels. However, by setting the allowable range of pixel values to be narrow, the possibility of selecting a pixel in which a subject different from the subject in the target pixel is selected is reduced. For example, when the pixel value is represented by 0 to 255, the second allowable range is set to the reference value ± 15.

  FIG. 4A is a diagram illustrating an example of the filter range set for the target pixel of the target image and the selected pixel. In FIG. 4A, the numerical value shown in each pixel of the target image 400 indicates the value of that pixel. In this example, a filter region 410 of 3 × 3 pixels centering on the pixel of interest 401 is set. Assuming that the first allowable range is a range of ± 25 with respect to the pixel value 192 of the pixel of interest 401, in addition to the pixel of interest 401, the pixel 402 adjacent to the left of the pixel of interest 401 (pixel value 185), the lower left pixel 403 (pixel value 203) and lower right pixel 404 (pixel value 190) are selected.

  FIG. 4B is a diagram illustrating an example of a filter range and a selected pixel that are set with respect to the reference image 420 for the target image shown in FIG. In FIG. 4B, the numerical value shown in each pixel indicates the value of that pixel. In this example, a filter region 430 of 5 × 5 pixels centering on a reference pixel 421 located at the same position as the target pixel is set. Assuming that the second allowable range is a range of ± 15 with respect to the pixel value 192 of the target pixel 401 shown in FIG. 4A, the seven pixels 422 indicated by hatching are selected.

  When a plurality of reference images are set, the temporally similar pixel selection unit 12 may increase the size of the filter region as the filter region is set for the reference image that is temporally separated from the target image. . The time-similar pixel selection unit 12 may narrow the second allowable range set for the reference image that is temporally separated from the target image.

  For each reference image, the time-similar pixel selection unit 12 notifies the combining unit 13 of information indicating the position of the selected pixel together with identification information indicating the reference image.

The synthesizing unit 13 synthesizes the value obtained by synthesizing the pixel value of the pixel on the target image selected by the spatially similar pixel selecting unit 11 and the pixel value of the pixel selected by the time-similar pixel selecting unit 12. The correction value of the target pixel on the target image is calculated. In the present embodiment, the synthesis unit 13 sets the average value of the selected pixels as the value of the target pixel on the target image. For example, in the example of the selected pixel shown in FIGS. 4A and 4B, the average value of the selected pixels is (192 + 185 + 203 + 190 + 190 + 185 + 188 + 187 + 195). Since + 204 + 199) /11=192.5, 192 which is an integer part of the average value is the value of the target pixel.
The synthesizing unit 13 calculates the pixel value of the pixel on the target image selected by the spatially similar pixel selection unit 11 and the median value of the pixel value of the pixel selected by the time-similar pixel selection unit 12 on the target image. The correction value of the target pixel may be used. In this case, in the example of the selected pixel shown in FIGS. 4A and 4B, the median value of the value of the selected pixel is 190, and thus the correction value of the target pixel is 190.

FIG. 5 is an operation flowchart of image correction processing executed by the image correction device 6.
The image correction device 6 reads an image to be processed as a noticed image from images stored in the storage unit 5 and reads at least one reference image generated before or after the noticed image. (Step S101).
The image correction device 6 sets a pixel that is not set as the target pixel among the pixels on the target image as the target pixel (step S102). For example, the image correction apparatus 6 sequentially sets each pixel as a target pixel according to the raster scan order in order from the upper left pixel.

  The space-similar pixel selection unit 11 sets a filter area around the target pixel on the target image (step S103). Then, the space-similar pixel selection unit 11 selects a pixel having a pixel value included in the first allowable range set with the value of the target pixel as a reference value in the filter region (step S104). The spatially similar pixel selection unit 11 notifies the synthesis unit 13 of information indicating the position of the pixel selected on the target image.

  In addition, the time-similar pixel selection unit 12 sets a filter area for each reference image around the reference pixel located at the same position as the target pixel on the reference image (step S105). Then, the time-similar pixel selection unit 12 selects a pixel having a pixel value included in the second allowable range set with the value of the target pixel as a reference value in the filter region (step S106). For each reference image, the time-similar pixel selection unit 12 notifies the combining unit 13 of information indicating the position of the selected pixel together with identification information indicating the reference image.

The synthesizing unit 13 calculates a value obtained by synthesizing the values of the selected pixels as a correction value for the target pixel (step S107). As described above, the value obtained by combining the values of the selected pixels can be, for example, the average value or the median value of the values of the selected pixels.
Thereafter, the image correction device 6 determines whether or not there remains a pixel that is not set as the target image on the target image (step S108). When the pixel which is not set to the attention image remains on the attention image (Step S108-Yes), the image correction device 6 repeats the processing after Step S102.

On the other hand, when there are no remaining pixels that are not set in the target image on the target image (step S108-No), the image correction device 6 has corrected each pixel to have a pixel value corrected by the image correction process. The attention image is output to the control unit 7 (step S109). The image correction device 6 may store the corrected attention image in the storage unit 5. Then, the image correction device 6 ends this image correction process.
Note that the image correction apparatus 6 may execute the processes in steps S103 and S104 and the processes in steps S105 and S106 in parallel. Alternatively, the image correction apparatus 6 may change the order of the processes in steps S103 and S104 and the processes in steps S105 and S106.

  Note that the corrected attention image output from the image correction device 6 may be used as a reference image for another image.

  As described above, this image correction apparatus sets a filter area having a certain size for the reference image, and a pixel having a value close to the value of the target pixel from within the filter area. Are selected to correct the value of the pixel of interest. The pixel selected in this way is highly likely to contain the same subject as that of the subject shown in the target pixel. Therefore, this image correction apparatus can obtain a 3DNR effect while preventing blurring due to an afterimage even if the subject shown in the target pixel is a moving object. In addition, this image correction apparatus can select a pixel that has a high possibility that the same subject as the subject that appears in the pixel of interest appears without performing tracking processing. Therefore, this image correction apparatus can use a plurality of images generated at different times for suppressing noise components of pixel values while suppressing an increase in the amount of calculation.

In addition, this invention is not limited to said embodiment. According to the modification, the time-similar pixel selection unit 12 checks whether or not the value of the pixel is included in the second allowable range in order from the pixel closest to the reference pixel in the set filter region. Thus, the selection of pixels may be terminated when the first predetermined number of pixels is selected.
For example, if the subject shown in the target pixel is a static object, there is a possibility that on the reference image, the closer to the reference pixel located at the same position as the target pixel, the same subject as the subject shown in the target pixel may appear. Is expensive. Therefore, the time-similar pixel selection unit 12 performs pixel selection in order from the pixel closest to the reference pixel, thereby determining whether or not the pixel value is included in the allowable range for all the pixels in the filter region. Sometimes it is not necessary to investigate. As a result, the time-similar pixel selection unit 12 can reduce the calculation amount.
The first predetermined number is set to, for example, less than ½ of the total number of pixels included in the filter region set on the reference image, for example, 12.

  FIG. 6 is a diagram illustrating an example of the order of pixel selection with respect to the reference image in this modification. In this example, the arrow 600 represents the order of pixel selection for each pixel in the filter region 610. As indicated by an arrow 600, the reference pixel 601 is first selected as a target of selection processing, and then the pixel 602 adjacent to the left of the reference pixel 601 is selected as a target of selection processing. Thereafter, the pixels to be subjected to selection processing are sequentially set clockwise. Note that the pixels to be selected may be sequentially set counterclockwise with the reference pixel 601 as the center.

Similarly, the spatially similar pixel selection unit 11 also checks whether or not the value of the pixel is included in the first allowable range in order from the pixel closest to the target pixel, so that the second predetermined number of pixels are determined. The pixel selection may be terminated when selected. Thereby, the space similar pixel selection part 11 can reduce the amount of calculations.
The second predetermined number is set to, for example, 1/2 of the total number of pixels included in the filter region set on the target image, for example, 5.

  FIG. 7 is a diagram illustrating an example of the order of pixel selection with respect to the target image in this modification. In this example, an arrow 700 represents the order of pixel selection for each pixel in the filter region 710. As indicated by an arrow 700, the target pixel 701 is first selected as a target of selection processing, and then the pixel 702 adjacent to the left of the target pixel 701 is selected as a target of selection processing. Thereafter, the pixels to be subjected to selection processing are sequentially set clockwise. Note that the target pixel 701 itself is always selected. Further, the pixels to be selected may be sequentially set counterclockwise with the target pixel 701 as the center.

Further, if a sufficient number of pixels are selected from the reference image, the 3DNR effect can be obtained, and therefore the number of pixels selected from the target image itself may be small. Therefore, the spatially similar pixel selection unit 11 does not change the first pixel around the target pixel only when the number of pixels selected from the reference image (hereinafter referred to as the selected pixel number) does not reach the first predetermined number. You may select the pixel with the pixel value contained in the tolerance | permissible_range. In this case, the spatially similar pixel selection unit 11 selects, from the filter region set around the pixel of interest, the maximum number of pixels obtained by subtracting the number of selected pixels from the first predetermined number. At that time, the space-similar pixel selection unit 11 may select pixels in the order from the target pixel as described above. In this modification as well, the spatially similar pixel selection unit 11 selects the target pixel itself regardless of whether or not the number of selected pixels has reached the first predetermined number.
In addition, when there are a plurality of reference images, the spatial similarity pixel selection unit 11 determines the first allowable range around the pixel of interest only when the sum of the selection pixels from all the reference images does not reach the first predetermined number. A pixel having a pixel value included therein may be selected.

According to still another modification, the image correction apparatus uses the target pixel within a filter region set around the target pixel of the target image in order to determine a reference value for setting an allowable range of the pixel value. A pixel having a pixel value within a range centered on the value of may be selected. Then, the image correction apparatus may set the first and second allowable ranges using the average value or median value of the selected pixel value and the target pixel value as a reference value. In this case, it is preferable that the pixel value range for selecting a pixel for setting the reference value is set narrower than the first allowable range. As a result, the image correction apparatus can smooth the noise component rather than using the value of the target pixel itself as a reference value, so that a more appropriate allowable range can be set.
In addition, the image correction apparatus may vary the width from the reference value to the upper limit and the width from the reference value to the lower limit for at least one of the first and second allowable ranges.

  According to still another modification, the image correction apparatus may execute the image correction process according to the above-described embodiment or modification only for some pixels on the target image. For example, when the pixel value represents a luminance value, the influence of the noise component decreases as the gain set for the camera module 2 decreases and the pixel value increases. Therefore, for example, the image correction apparatus may not perform the image correction process on pixels whose gain is equal to or smaller than a predetermined value and whose pixel value is equal to or larger than a predetermined threshold. Thereby, the image correction apparatus can further reduce the amount of calculation for the entire image of interest. Note that the predetermined value of the gain is set to a value corresponding to ISO 100 to ISO 200, for example, and the threshold value of the pixel value is set to 127 to 200, for example, when the pixel value is represented by 8 bits.

  According to still another modified example, the image correction apparatus may adjust the color balance on the corrected image, or execute processing such as edge enhancement or contrast enhancement instead of the control unit 7.

  The function of each unit of the image correction apparatus according to the above-described embodiment or its modification may be realized by a computer program executed on a processor. Such a computer program may be provided in a form recorded on a computer-readable recording medium such as a magnetic recording medium or an optical recording medium.

FIG. 8 is a configuration diagram of a computer that operates as an image correction apparatus by operating a computer program that realizes the functions of the respective units of the image correction apparatus according to the above-described embodiment or its modification.
The computer 100 includes a user interface unit 101, a communication interface unit 102, a storage unit 103, a storage medium access device 104, and a processor 105. The processor 105 is connected to the user interface unit 101, the communication interface unit 102, the storage unit 103, and the storage medium access device 104 via, for example, a bus.

  The user interface unit 101 includes, for example, an input device such as a keyboard and a mouse, and a display device such as a liquid crystal display. Alternatively, the user interface unit 101 may include a device such as a touch panel display in which an input device and a display device are integrated. For example, the user interface unit 101 outputs an operation signal for starting the image correction process to the processor 105 in accordance with a user operation.

The communication interface unit 102 may include a communication interface for connecting the computer 100 to an imaging device (not shown) capable of generating a plurality of temporally continuous images and a control circuit thereof. Such a communication interface can be, for example, Universal Serial Bus (Universal Serial Bus, USB).
Furthermore, the communication interface unit 102 may include a communication interface for connecting to a communication network according to a communication standard such as Ethernet (registered trademark) and a control circuit thereof.
In this case, the communication interface unit 102 acquires a plurality of temporally continuous images from other devices connected to the communication network, and causes the storage unit 103 to store the plurality of images. Further, the communication interface unit 102 may output the corrected image received from the processor 105 to another device via a communication network.

  The storage unit 103 includes, for example, a readable / writable semiconductor memory and a read-only semiconductor memory. The storage unit 103 stores a computer program for executing an image correction process executed on the processor 105, an intermediate calculation result obtained during the image correction process, and the like. In addition, the storage unit 103 stores an image received from the communication interface unit 102 or a corrected image generated by the processor 105.

  The storage medium access device 104 is a device that accesses a storage medium 106 such as a magnetic disk, a semiconductor memory card, and an optical storage medium. For example, the storage medium access device 104 reads a computer program for image correction processing executed on the processor 105 stored in the storage medium 106 and passes the computer program to the processor 105. The storage medium access device 104 may write the corrected image generated by the processor 105 into the storage medium 106.

  The processor 105 executes the image correction processing computer program according to the above-described embodiment or modification, thereby generating a corrected image in which the noise component included in the value of each pixel of the image to be processed is reduced. Then, the processor 105 saves the generated corrected image in the storage unit 103 or outputs it to another device via the communication interface unit 102.

  All examples and specific terms listed herein are intended for instructional purposes to help the reader understand the concepts contributed by the inventor to the present invention and the promotion of the technology. It should be construed that it is not limited to the construction of any example herein, such specific examples and conditions, with respect to showing the superiority and inferiority of the present invention. Although embodiments of the present invention have been described in detail, it should be understood that various changes, substitutions and modifications can be made thereto without departing from the spirit and scope of the present invention.

The following supplementary notes are further disclosed regarding the embodiment described above and its modifications.
(Appendix 1)
A first filter region is set around a pixel of interest on the first image, and a first reference region including a predetermined reference value set based on the value of the pixel of interest is selected from the first filter region. A first pixel selection unit that selects a first pixel having a pixel value within an allowable range;
A second filter region is set around a reference pixel located at the same position as the target pixel on at least one second image generated before or after the first image, and the second filter region; A second pixel selection unit that selects a second pixel having a pixel value within a second allowable range including the predetermined reference value,
A combining unit that sets a value obtained by combining the value of the first pixel and the value of the second pixel as a correction value of the target pixel;
An image correction apparatus.
(Appendix 2)
The second pixel selection unit selects pixels having a value included in the second allowable range in order from a pixel close to the reference pixel among pixels included in the second filter region. The image correction apparatus according to claim 1, wherein the second pixel selection is stopped when the number of the selected second pixels reaches a first predetermined number.
(Appendix 3)
When the number of the selected second pixels is less than the first predetermined number, the first pixel selection unit is included in the first allowable range in order from the pixel closest to the target pixel. A pixel having a value is selected as the first pixel, and when the sum of the number of the selected first pixels and the number of the second pixels reaches the first predetermined number, the first pixels The selection according to claim 2, wherein when the number of the selected second pixels reaches the first predetermined number, only the target pixel is selected as the first pixel. Image correction device.
(Appendix 4)
The first pixel selection unit selects pixels having values included in the first allowable range in order from a pixel close to the target pixel among pixels included in the first filter region. The image correction apparatus according to appendix 1 or 2, wherein when the number of the selected first pixels reaches a second predetermined number, the selection of the first pixels is stopped.
(Appendix 5)
The image correction apparatus according to claim 1, wherein the second allowable range is narrower than the first allowable range.
(Appendix 6)
The image correction apparatus according to claim 1, wherein the reference value is a value of the target pixel.
(Appendix 7)
The reference value is an average value or a median value of pixels having values included in a predetermined pixel value range among pixels included in the first filter region. The image correction apparatus according to any one of appendices 1 to 6, wherein the range includes a value of the target pixel and is narrower than the first allowable range.
(Appendix 8)
The value obtained by combining the value of the first pixel and the value of the second pixel is an average value or a median value of the value of the first pixel and the value of the second pixel. The image correction apparatus according to any one of appendices 1 to 7.
(Appendix 9)
A first filter region is set around a pixel of interest on the first image, and a first reference region including a predetermined reference value set based on the value of the pixel of interest is selected from the first filter region. Selecting a first pixel having a pixel value within an acceptable range;
A second filter region is set around a reference pixel located at the same position as the target pixel on at least one second image generated before or after the first image, and the second filter region; A second pixel having a pixel value within a second allowable range including the predetermined reference value is selected from
A value obtained by combining the value of the first pixel and the value of the second pixel is set as a correction value of the target pixel.
An image correction method.
(Appendix 10)
A first filter region is set around a pixel of interest on the first image, and a first reference region including a predetermined reference value set based on the value of the pixel of interest is selected from the first filter region. Selecting a first pixel having a pixel value within an acceptable range;
A second filter region is set around a reference pixel located at the same position as the target pixel on at least one second image generated before or after the first image, and the second filter region; A second pixel having a pixel value within a second allowable range including the predetermined reference value is selected from
A value obtained by combining the value of the first pixel and the value of the second pixel is set as a correction value of the target pixel.
An image correction computer program for causing a computer to execute the above.

DESCRIPTION OF SYMBOLS 1 Imaging device 2 Camera module 3 Operation part 4 Display part 5 Memory | storage part 6 Image correction apparatus 7 Control part 11 Spatial similarity pixel selection part (1st pixel selection part)
12-hour similar pixel selector (second pixel selector)
DESCRIPTION OF SYMBOLS 13 Synthesis | combination part 100 Computer 101 User interface part 102 Communication interface part 103 Storage part 104 Storage medium access apparatus 105 Processor 106 Storage medium

Claims (6)

A first filter region is set around a pixel of interest on the first image, and a first reference region including a predetermined reference value set based on the value of the pixel of interest is selected from the first filter region. A first pixel selection unit that selects a first pixel having a pixel value within an allowable range;
A second filter region is set around a reference pixel located at the same position as the target pixel on at least one second image generated before or after the first image, and the second filter region; A second pixel selection unit that selects a second pixel having a pixel value within a second allowable range including the predetermined reference value,
A combining unit that sets a value obtained by combining the value of the first pixel and the value of the second pixel as a correction value of the target pixel;
An image correction apparatus.   The second pixel selection unit selects pixels having a value included in the second allowable range in order from a pixel close to the reference pixel among pixels included in the second filter region. 2. The image correction apparatus according to claim 1, wherein selection of the second pixel is stopped when the number of the selected second pixels reaches a first predetermined number.   When the number of the selected second pixels is less than the first predetermined number, the first pixel selection unit is included in the first allowable range in order from the pixel closest to the target pixel. A pixel having a value is selected as the first pixel, and when the sum of the number of the selected first pixels and the number of the second pixels reaches the first predetermined number, the first pixels The selection of the second pixel is stopped, and when the number of the selected second pixels has reached the first predetermined number, only the target pixel is selected as the first pixel. Image correction device.   The image correction apparatus according to claim 1, wherein the second allowable range is narrower than the first allowable range. A first filter region is set around a pixel of interest on the first image, and a first reference region including a predetermined reference value set based on the value of the pixel of interest is selected from the first filter region. Selecting a first pixel having a pixel value within an acceptable range;
A second filter region is set around a reference pixel located at the same position as the target pixel on at least one second image generated before or after the first image, and the second filter region; A second pixel having a pixel value within a second allowable range including the predetermined reference value is selected from
A value obtained by combining the value of the first pixel and the value of the second pixel is set as a correction value of the target pixel.
An image correction method. A first filter region is set around a pixel of interest on the first image, and a first reference region including a predetermined reference value set based on the value of the pixel of interest is selected from the first filter region. Selecting a first pixel having a pixel value within an acceptable range;
A second filter region is set around a reference pixel located at the same position as the target pixel on at least one second image generated before or after the first image, and the second filter region; A second pixel having a pixel value within a second allowable range including the predetermined reference value is selected from
A value obtained by combining the value of the first pixel and the value of the second pixel is set as a correction value of the target pixel.
An image correction computer program for causing a computer to execute the above.

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