JP2021150925A - Imaging apparatus and image processing method - Google Patents

Abstract

To solve the problem in which, when photographing a small star, if an input signal to a sensor is a single-pixel wide, R or B information may be missing, causing false colors in the star.SOLUTION: By looking for pixels that have been exposed to the same star from a sequentially numbered image and using color information from the pixel with the highest signal level to compensate for the lack of color information, false colors in small stars can be prevented.SELECTED DRAWING: Figure 1

Description

The present invention relates to a false color reduction processing method for captured images.

Due to the trend of cost reduction and emphasis on resolution, the number of optical LPF-less cameras is increasing for compact cameras and single-lens cameras for beginners and intermediate users. In addition, since the sensitivity of the image sensor of a digital camera has been improved and the S / N has also been improved, there is also a model equipped with a mode that allows easy shooting of the starry sky. There is a mode to shoot a perfect starry sky and a mode to shoot the trajectory of diurnal motion in which stars move with time.

Patent Document 1 proposes a mode in which the trajectory of the starry sky is photographed a plurality of times, and comparative bright composition is performed in which the trajectory is not interrupted between the captured images.

JP-A-2015-233238

However, when the trajectory of the starry sky is photographed by the method of Document 1, especially in a model without an optical LPF or a model in which an optical LPF is included in only one of the vertical and horizontal directions, when the starry sky trajectory image is photographed by the above method, about a small star. Since the input signal to the sensor may have a single pixel width, there is a problem that R or B information is lost and false color is generated.

An object of the present invention is to provide an imaging device capable of capturing a starry sky image that reproduces the original star color by suppressing the generation of false colors when the starry sky is photographed.

In order to solve the above problems, the image pickup apparatus of the present invention includes an imaging unit 2 that obtains serial number images by continuous shooting, a synthesis unit 12 that synthesizes the serial number images to obtain a starry sky trajectory image, and the series. The star determination unit 203 that determines the star pixels in the starry sky trajectory image using the number image and groups the pixels belonging to the same star with respect to the star pixels, and the star pixels belonging to the same star for each plane. A color signal that calculates replacement color information to be used for replacement using the color information of star pixels belonging to the same star, and replaces the color information of the target pixel with the replacement color information for the star pixel belonging to the same star. The color signal replacement unit 205 includes a replacement unit 205, and the color signal replacement unit 205 uses the following formula 1 to set a color representative value Col (xmax, ymax) at the level of OG (xmax, ymax) at the same position as the color representative value. It is characterized in that the replacement color information Col (x, y) is calculated by normalization.
Col (x, y) = Col (xmax, ymax) × OG (x, y) / OG (xmax, ymax) ・ ・ ・ Equation 1

In addition, other features of the present invention will be further clarified by the accompanying drawings and the description in the form for carrying out the following invention.

According to the present invention, it is possible to obtain a starry sky image that reproduces the original star color by suppressing the occurrence of false colors, particularly when the starry sky is photographed with a camera having little effect of the optical LPF.

It is a block diagram of this invention. It is a figure which showed the flow of the starry sky trajectory shooting mode. It is a star information table which shows a star determination result. It is a block diagram of the false color reduction part 13. This is the screen for selecting the shooting mode of the starry sky. It is a figure which showed the flow of the false color reduction processing of this invention. It is a schematic diagram of the serial number image taken in the starry sky locus photography mode, and the image to which this invention is applied. It is a star information table corresponding to the serial number image of FIG.

(First Embodiment)
Hereinafter, preferred embodiments of the present invention will be described.

In the present embodiment, as an example of an image processing device to which the present invention can be applied, an image processing device having an imaging system such as a digital camera or a scanner will be mentioned. However, the present invention is not limited to this, and the embodiment is not particularly limited as long as it is an image processing device capable of processing image data. That is, the image processing device may be an information processing device such as a personal computer, or an image forming device such as a portable information terminal or a printer. This also applies to each of the following embodiments.

(Basic configuration of image processing device 100)
FIG. 1 is a block diagram of a digital camera which is an example of the image processing device 100 in the present embodiment.

In the image processing device 100, a subject (not shown) is imaged on the image sensor 2 by the image pickup optical system of the lens unit 1. In the focus lens 101, the position of the lens is controlled by an autofocus (AF) mechanism (not shown) or a manual manual focus mechanism in order to adjust the focus according to the distance of the subject. The aperture diameter of the aperture 102 is controlled as an F-number shooting state setting. The position of the zoom lens 103 is controlled by a manual manual zoom mechanism (not shown) in order to adjust the image magnification of the subject. The lens characteristic information recording unit 104 records information such as a lens ID, a focal length of a lens, and discrete correction values.

The image sensor 2 is, for example, a single-plate color image sensor provided with a general primary color filter. The primary color filters consist of three types of color filters having transmission main wavelength bands near 650 nm, 550 nm, and 450 nm, respectively, and color planes corresponding to the R (red), G (green), and B (blue) bands, respectively. To shoot. In the single-plate color image sensor, the color filters are spatially arranged in a mosaic pattern for each pixel, and each pixel obtains the intensity in a single color plane. Therefore, the image sensor 2 outputs a color mosaic image. become.

The A / D conversion unit 3 converts the electric signal obtained by the image sensor 2 into a digital image signal. In the present embodiment, 12-bit image data is generated for each pixel at this point.

The simultaneous unit 4 performs simultaneous processing on the digital image signal output from the A / D conversion unit 3.

The compositing unit 12 performs a comparative bright compositing process of the digital image signal output from the simultaneous unit 4 and the digital image signal read from the memory 11.

The false color reduction unit 13 uses the digital image signal output from the simultaneous unit 4 to perform false color reduction processing on the comparatively bright composite image signal output from the synthesis unit 12.

The development processing unit 5 performs a series of development processing such as lens optical correction processing, brightness signal processing, and color signal processing on the digital image signal output from the false color reduction unit 13. In the present embodiment, the color space of R, G, and B is converted into the color space of 8-bit luminance (Y) data and color difference (U, V) data by the processing of the development processing unit 5, and the development processing unit 5 is converted into YUV data. It shall be output from.

The output processing unit 6 performs resizing processing or the like on the developed image data and supplies the image data to the output unit 7. The output unit 7 performs one or more of output to an output interface such as HDMI, recording to a recording medium such as a semiconductor memory card, and output to a display device (not shown) of the image processing device 100.

The UI unit 9 has one or more input devices such as switches, buttons, and a touch panel provided on a display device (not shown), and external operations such as instructions by the user are imaged via the UI unit 9. It is input to the processing device 100, and the control unit 10 receives this input to perform an calculation or controls each unit.

The control unit 10 controls each unit via the bus 8 and performs necessary arithmetic processing as appropriate.

The memory 11 stores image data used in each processing unit and data of information at the time of shooting such as aperture value, shutter speed, ISO sensitivity, white balance gain value, and color gamut setting such as s-RGB. The stored data is appropriately read out and used according to the instruction of the control unit 10. Each component shown in FIG. 1 is communicably connected to each other via a bus 8.

(Details of starry sky trajectory shooting process)
FIG. 5 is a screen for selecting a shooting mode of the starry sky.

The user can operate the UI unit 9 to select the shooting mode of the starry sky. If you want to shoot the starry sky without flowing the stars in the captured image, select the starry night view mode, and if you want to shoot the trajectory of the moving stars, select the starry sky trajectory mode.

In the selected mode, the control unit 10 writes the mode information to the memory 11 and stores the mode selected by the user. In this embodiment, it is assumed that the starry sky trajectory mode is selected.

FIG. 2 is a diagram showing the flow of the starry sky trajectory shooting mode.

When the user operates the UI unit 9 to give a shooting instruction, the control unit 10 reads the mode stored in the memory 11 and performs the shooting process of the designated shooting mode.

If the stored shooting mode is the starry sky trajectory mode, the user sets the shooting time in advance in S201. Set a long shooting time when you want to shoot a long trajectory of a star, and set a short shooting time when you want to shoot a short trajectory. Usually, a shooting time of 1 to 2 hours is often set.

In S202, the aperture, shutter speed, and ISO sensitivity are set based on the light measurement result. In S203, a still image is photographed based on the exposure control set in S202, and a comparative bright composition process of the photographed image is performed in S204. In S206, the false color reduction process is performed on the captured image by using the false color reduction unit 13. Since the false color reduction process in S205 is the point of the present invention, it will be described in detail later.

In S207, the photographed image is developed by using the developing processing unit 5, and in S208, the image is written to a recording medium such as a semiconductor memory card.

(Details of false color reduction processing)
Hereinafter, a method of false color reduction processing executed by the image processing apparatus 100 and a configuration of an image processing circuit that realizes the method will be described.

FIG. 3 is a star information table 208. The star information table 208 can record the result of star determination for all pixels of the serial number image. The star information table 208 is created by the control unit 10 when the power is turned on or when the shooting mode is switched. Further, the false color reduction unit 13 adds and updates the star determination result every time the serial number image is input frame by frame.

FIG. 4 is a block diagram of the false color reduction unit 13. The false color reduction unit 13 calculates star information for each pixel with respect to the image data after simultaneousization each time a serial number image is input one by one, and adds and updates the star information to the star information table 208. .. Further, after all the serial number images necessary for creating the starry sky trajectory image are input and the composite unit 12 outputs a comparatively bright composite image of all frames of the serial number image, the false color reduction unit 13 sets the false color reduction unit 13. Using the star information table 208, the false color signal generated in the image data after the comparative bright composition is replaced with another color signal.

In the present embodiment, the false color reduction unit 13 performs a false color signal replacement process on the comparatively brightly synthesized starry sky trajectory image. This makes it possible to suppress the occurrence of false colors and obtain a starry sky trajectory image that reproduces the original star color.

The simultaneous unit 4 simultaneousizes the digital image signals output from the A / D conversion unit 3, and outputs the simultaneous plain image signals to the synthesis unit 10, the star determination unit 203, the motion determination unit 204, and the memory 11. do.

The star determination unit 203 calculates star information for each pixel with respect to the plain image signal output from the simultaneous unit 4, and adds it to the star information table 208 stored in the memory 11.

The motion determination unit 204 reads out the plane image signal 207a in the nth frame and the star information 208n regarding the plane image in the nth frame from the memory 11, and outputs the plane image signal in the n + 1th frame and the star determination unit in the simultaneous unit 4. The star information 208n is updated using the star information in the n + 1th frame output from 203.

The compositing unit 12 performs comparative bright compositing processing of serial number image signals obtained by continuous shooting. Further, after the serial number image signals of all frames are input and the comparative bright composition processing is completed, the image signal after the comparative bright composition is output to the development processing unit 5 as an image signal for brightness signal processing to perform color signal processing. It is output to the color signal replacement unit 205 as an image signal for use.

The color signal replacement unit 205 reads the star information table 208 from the memory 11 at the timing when the comparative bright composite image is input from the composite unit 12, and uses the information described in the star information table to refer to the comparative bright composite image. The color signal replacement process is performed to reduce the false color signal, and the image signal is output to the development processing unit 5 as an image signal for color signal processing.

The false color reduction process will be described in more detail in the image pickup apparatus configured as described above. FIG. 6 is a flowchart showing a false color reduction processing method in this embodiment.

First, the flow when the image of the first frame of the serial number image is output from the A / D conversion unit 3 will be described with reference to FIGS. 6 and 4 (a). FIG. 4A is a block diagram showing a block and a data flow related to false color reduction processing when the image of the first frame of the serial number image is output.

In step S602, the simultaneous unit 4 simultaneously synchronizes the image signal of the first frame of the serial number image output from the A / D conversion unit 3 and outputs it to the memory 11, the synthesis unit 12, and the star determination unit 203. The image of the first frame of the serial number image output from the simultaneous unit 4 is stored in the memory 11 as the image 207a.

In step S603, the compositing unit 12 stores the input digital image signal as a comparative bright composite image 206 in the memory 11 as it is without modifying it.

In step S604, the star determination unit 203 performs the star pixel determination process. The star pixel determination process will be described in detail with reference to FIGS. 6A and 3A.

The star determination unit 203 reads out the image of the first frame of the serial number image output from the simultaneous unit 4 in step S6011, and performs star pixel determination in step S6012. The star determination unit 203 considers, for example, a pixel having a sufficiently high signal level with respect to the background as a star.

In step S6013, the star determination unit 203 adds the result of the star pixel determination to the star information table 208. The contents of the star information table 208 are shown in FIG. In the star information table 208, the horizontal axis corresponds to the width of the input image and the vertical axis corresponds to the height of the input image, and a flag indicating whether or not each pixel in the input image is a star is described. In step S6013, the star determination result of the first frame in the serial number image shown in FIG. 3A is added.

In step S6014, step S6015, and step S6016, if the frame output from the simultaneous unit 204 is the first frame of the serial number image, nothing is processed and the star pixel determination process is terminated.

Next, the flow when the image of the second frame of the serial number image is output from the A / D conversion unit 3 will be described with reference to FIGS. 6 and 4 (b). FIG. 4B is a block diagram showing a block and a data flow related to false color reduction processing when the image of the second frame of the serial number image is output.

In step S602, the simultaneous unit 4 simultaneously synchronizes the image signals of the second frame of the serial number images output from the A / D conversion unit 3 with the memory 11, the compositing unit 12, the star determination unit 203, and the motion determination unit 204. Output. The second frame image of the serial number image output from the simultaneous unit 4 is stored in the memory 11 as the image 207b.

In step S603, the compositing unit 12 performs comparative bright compositing of the comparative bright composite image 206 read from the memory 11 and the second frame image of the serial number image output from the simultaneous unit 4, and stores the comparative bright composite image 206 as the comparative bright composite image 206. Save to 11.

In step S604, the star determination unit 203 performs the star pixel determination process. The star pixel determination process will be described in detail with reference to FIGS. 6 (b) and 3.

The star determination unit 203 reads out the image of the second frame of the serial number image output from the simultaneous unit 4 in step S6011, performs star pixel determination in step S6012, and determines the star pixel determination result in step S6013 in the star information table 208. Add to. The star determination result of the second frame of the serial number image is shown in FIG. 3 (b).

The motion determination unit 204 determines the motion of the pixel determined to be a star by using the star information table 208 in step S6014, and updates the star information table 208 in step S6015. 3A and 3B are star determination results for the first frame image 207a of the serial number image and the second frame image 207b of the serial number image, respectively.

For example, as shown in FIG. 3, when the position of the pixel is represented by the distance (horizontal distance, vertical distance) from the starting point with the upper left of the image as the starting point (0, 0), the pixel (1, 1) in FIG. The value of is 1 and it is determined that a star exists, but the values of the pixels (1, 1) at the same position in FIG. 3 (b) and the values of all eight pixels adjacent to the pixels (1, 1) are also 0. It is determined that there are no stars. If the signal of the pixel (1, 1) in FIG. 3 (a) is a star, it should have moved to the same position or an adjacent pixel in FIG. 3 (b), which is the next frame of the serial number image. Therefore, since it can be seen that the signals of the pixels (1, 1) in FIG. 3A, which do not correspond to any of the above, are not stars, it is necessary to set the value to 0 and review the determination that the stars do not exist.

On the other hand, for the signal of the pixel (1, y-2) in FIG. 3 (a), which also has a value of 1 and is determined to have a star, the value at the same position in FIG. 3 (b) is also 1 and the star. Since it is determined that there is, there is no need to review the determination. Regarding the signal of the pixel (x-2, 1) in FIG. 3A, the value of the same position (x-2,1) in FIG. 3B is 0, but the value of the adjacent position (x−1) is 0. Since the values of 1 and 1) are 1, and it is considered that the star has moved between the frames, there is no need to review the judgment.

The motion determination unit 204 reviews the star determination result for all the pixels in FIG. 3A by the method described above. The result of reviewing the judgment of FIG. 3 (a) is shown in FIG. 3 (c). The data required for the color signal replacement process described later is only the star determination result for the image obtained by comparatively brightly synthesizing all the frames of the serial number image. Therefore, the motion determination unit 204 takes the logical sum of FIGS. 3 (b) and 3 (c) and stores it in the memory 11. A star information table created by ORing the logical sums of FIGS. 3 (b) and 3 (c) is shown in FIG. 3 (d).

Using the image 207b of the second frame of the serial number image output from the compositing unit 12, motion determination is performed for each pixel of the image 207a of the first frame of the serial number image read from the memory 11, and the result is obtained. You may use it to update the star determination result.

By reviewing the star judgment result using the motion judgment result as described above, for example, noise and pixel defects caused by the image sensor that occur only in a specific frame in the serial number image, subjects such as airplanes, etc. are unnecessary other than stars. It is possible to avoid erroneous determination by a signal.

After the processing of steps S601 to S605 is completed for all the frames of the serial number image, in step S606, the comparative bright composite image is output from the composite unit 12 to the false color reduction unit 13, and the false color reduction unit 13 The signal for color system processing is subjected to color signal replacement processing and then output to the development processing unit 5. The false color reduction unit 13 outputs the signal for luminance processing to the development processing unit 5 without performing any processing. The color signal replacement process will be described in detail with reference to FIGS. 6 (c), 4 (c), 7 and 8.

FIG. 4C is a block diagram showing a block and a data flow related to false color reduction processing when the N + 1th frame image of the serial number image is output when the total number of frames of the serial number image is N + 1. be. By the processing up to step S605, the memory 11 stores the comparative bright composite image 206 up to the N + 1th frame of the serial number image and the star information table showing the star determination results for all the pixels of the comparative bright composite image 206. .. FIG. 7 is a schematic view of serial number images taken in the starry sky trajectory shooting mode and images to which the present invention is applied. 7 (a), (b), and (c) are images of the k-th frame, k + 1-th frame, and k + 2nd frame of the serial number image, respectively, and FIG. 7 (d) is a comparative bright composition result of the serial number image. Is. In this embodiment, a starry sky locus with a pixel width extending from the upper left of the screen to the lower right of the screen as shown in FIG. 7D is input. FIG. 8 is a star information table corresponding to the comparative bright composite image of FIG. 7 (d).

In step S6021, the color signal conversion unit 205 reads the star information table 208 from the memory 11 and searches for the star-determined pixel. For example, the upper left corner of the image may be the starting point (0, 0), and the search may be performed pixel by pixel toward the lower right corner of the image. If a star-determined pixel is found, the process proceeds to step S6022. If no star-determined pixel is found even after searching all the pixels, the process proceeds to step S6026.

In step S6022, the color signal conversion unit 205 groups star pixels belonging to the same star as the star-determined pixel found in step S6021. Grouping may be performed using a known contour tracking method.

The color signal conversion unit 205 decomposes the Bayer-format comparative bright composite image output from the composite unit 12 into RGB planes. A comparatively bright composite image decomposed into RGB planes is shown in FIG. 7 (e). Since the starry sky locus in this embodiment has a pixel width, R pixels and B pixels can be arranged only every two rows. Therefore, when decomposed into RGB planes, R or B pixels in the pixels through which the starry sky locus passes are Any information will always be missing. The color signal conversion unit 205 then performs color complement processing on the RGB plain image. A known method may be used for the color complement processing, but in this embodiment, for example, adaptive complementation is performed using the vertical and horizontal edge discrimination results after 0 insertion for the G plane, and vertical and horizontal after 0 insertion for the R plane and B plane. The average value of adjacent pixels is used.

A comparatively bright composite image after color complementation is shown in FIG. 7 (f). The information of either R or B that was missing at the time of decomposition into the RGB plane remains missing even after color complementation, and if the development is performed as it is, a false color different from the original star color will be generated. Therefore, in this embodiment, for the star pixels belonging to the same grouped star, the representative values of the R plane and the B plane are selected, and the missing R or B information is replaced by using the selected representative values. do.

In step S6023, the color signal conversion unit 205 selects the color representative values of the star pixels belonging to the same grouped stars. When selecting the color representative value of the R plane, the R plane after color complementation shown in FIG. 7 (f) is masked by the star information table 208 shown in FIG. 8, and the maximum value of the extracted R pixels is set to the maximum value of the R plane. Let the color representative value R (xmax, ymax) be used. In this embodiment, the value of the R pixel circled in FIG. 7 (f) is used as the color representative value of the R plane. Similarly, for the B plane, the B plane after color complementation shown in FIG. 7 (f) is masked by the star information table 208 shown in FIG. 8, and the maximum value of the extracted B pixels is set as the color representative value B (xmax, xmax, ymax). In this embodiment, the value of the B pixel circled in FIG. 7 (f) is used as the color representative value of the B plane.

In step S6024, the color signal conversion unit 205 calculates the replacement color information of the R plane and the B plane using the color representative value, and replaces the information of the R plane and the B plane of the star pixel. When calculating the replacement color information of the R plane, the R plane after color complementation shown in FIG. 7 (f) is masked by the star information table 208 shown in FIG. For the R pixel extracted as a star pixel belonging to the same star, the color signal conversion unit 205 uses the following equation 2 to set the color representative value R (xmax, ymax) to the G plane signal at the same position as the color representative value. The replacement color information R (x, y) is calculated by normalizing at the level of G (xmax, ymax), and the value of the R pixel is replaced with this value.
R (x, y) = R (xmax, ymax) × G (x, y) / G (xmax, ymax) ・ ・ ・ Equation 2

When calculating the replacement color information of the B plane, the B plane after color complementation shown in FIG. 7 (f) is masked by the star information table 208 shown in FIG. For the B pixel extracted as a star pixel belonging to the same star, the color signal conversion unit 205 uses the following formula 3 to set the color representative value B (xmax, ymax) to the G plane signal at the same position as the color representative value. The replacement color information B (x, y) is calculated by normalizing at the level of G (xmax, ymax), and the value of the B pixel is replaced with this value.
B (x, y) = B (xmax, ymax) × G (x, y) / G (xmax, ymax) ・ ・ ・ Equation 3

FIG. 7 (g) shows the result of replacing the pixel values of the R pixel and the B pixel with the replacement color information. The information of either R or B, which was missing at the time after color complementation, is supplemented, and all RGB information exists for the place where the starry sky trajectory passed. The result of developing this is shown in FIG. 7 (h). Since all the information of RGB exists, the generation of false color is suppressed and the original color of the starry sky trajectory is reproduced.

In step S6025, the color signal conversion unit 205 edits the star information table 208 so that the star determination of the pixels grouped in S6022 is set to 0. This prevents the color information of the pixels belonging to one star from being mistakenly used for the color information of another star.

In step S6026, the color signal conversion unit 205 confirms whether the search for the star-determined pixels has been performed for all the pixels, that is, whether the values of all the pixels in the star information table 208 are 0. If there is a pixel for which the search has not been completed, the process returns to S6021. When the search for all the pixels is completed, the color signal conversion unit 205 outputs a series of false color reduction processed images to the development processing unit 5.

In this embodiment, the case of photographing the starry sky trajectory has been described as an example, but it can be applied to other than the starry sky trajectory. For example, it is effective when shooting the trajectory of a car light in night view shooting, shooting a moving subject, and the like.

The present invention is not limited to those illustrated in each of the above embodiments, and can be appropriately modified without departing from the gist of the present invention.

(Other embodiments)
The present invention supplies a program that realizes one or more functions of the above-described embodiment to a system or device via a network or storage medium, and one or more processors in the computer of the system or device reads and executes the program. It can also be realized by the processing to be performed. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

1 Lens unit 2 Image sensor 3 A / D conversion unit 4 Simultaneous unit 5 Development processing unit 6 Output processing unit 7 Output unit 9 UI unit 10 Control unit 12 Synthesis unit 13 False color reduction unit 203 Star determination unit 205 Color signal replacement unit

Claims (6)

An imaging unit that takes continuous shots and obtains serial number images,
A compositing unit that synthesizes the serial number images to obtain a starry sky trajectory image,
A star determination unit that determines star pixels in the starry sky trajectory image using the serial number image and groups pixels belonging to the same star with respect to the star pixels.
For the star pixels belonging to the same star, the replacement color information used for replacement is calculated by using the color information of the star pixels belonging to the same star for each plane, and the replacement color is calculated for the star pixels belonging to the same star. A color signal replacement unit that replaces the color information of the target pixel using information,
With
The color signal replacement unit normalizes the color representative value Col (xmax, ymax) at the level of OG (xmax, ymax) at the same position as the color representative value using the following formula 1, thereby performing replacement color information. An imaging device characterized by calculating Col (x, y).
Col (x, y) = Col (xmax, ymax) × OG (x, y) / OG (xmax, ymax) ・ ・ ・ Equation 1 The claim is characterized in that the star determination unit determines as a star pixel a pixel having a sufficiently high signal level with respect to the background, adjacent frames at the same location or adjacent to each other, and the pixel area does not change significantly between frames. The imaging apparatus according to 1. The imaging device according to claim 1, wherein the color signal replacement unit uses the largest pixel value among star pixels belonging to the same star as the pixel to be replaced as replacement color information. The first aspect of claim 1, wherein the color signal replacement unit acquires a plurality of maximum pixel values among star pixels belonging to the same star as the pixel to be replaced, and uses the median value as replacement color information. Imaging device. The color signal replacement unit acquires a plurality of pixel values exceeding the threshold value among the star pixels belonging to the same star as the replacement target pixel, and uses the value weighted by the distance from the replacement target pixel as the replacement color information. The imaging apparatus according to claim 1. Input means to obtain serial number images and
A compositing means for synthesizing the serial number images to obtain a starry sky trajectory image,
A star determination means for determining star pixels in the starry sky trajectory image using the serial number image and grouping pixels belonging to the same star with respect to the star pixels.
For the star pixels belonging to the same star, the replacement color information used for replacement is calculated by using the color information of the star pixels belonging to the same star for each plane, and the replacement color is calculated for the star pixels belonging to the same star. A color signal replacement means that replaces the color information of the target pixel using information,
Have,
The color signal replacement means uses the following formula 1 to normalize the color representative value Col (xmax, ymax) at the level of OG (xmax, ymax) at the same position as the color representative value, thereby causing the replacement color information. An image processing method characterized by calculating Col (x, y).
Col (x, y) = Col (xmax, ymax) × OG (x, y) / OG (xmax, ymax) ・ ・ ・ Equation 1

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