JP2011071709A - Electronic camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic camera which suitably eliminates dark-current noise from an image obtained through regular photographing. <P>SOLUTION: The electronic camera includes an imaging device which has an effective pixel area where pixels for photoelectrically converting object light into signal charge are arranged two-dimensionally, wherein two or more pixels among the pixels arranged in the effective pixel area are constituted of light-shielding pixels for shielding the object light; a setting section for dividing and setting the effective pixel area into a plurality of areas so as to make each of the areas include the light-shielding pixels; and a correcting section for correcting the pixel value of pixels included in the areas by area, on the basis of the pixel value of the light-shielding pixels included in the areas which are divided and set by the setting section at imaging by the imaging device. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electronic camera.

  In a digital camera which is a form of a commonly provided electronic camera, an image sensor such as a CCD or a CMOS is generally used. When imaging is performed using a digital camera using such an image sensor, main shooting in which the subject light to be irradiated is photoelectrically converted and light-shielded shooting in which shooting is performed while the subject light is shielded are executed. After these shootings, correction processing for an image obtained by actual shooting (hereinafter referred to as “main image”) is executed using an image obtained by shading shooting (hereinafter referred to as “light-shielded image”). An image from which noise components (hereinafter referred to as dark current noise) are removed can be acquired.

Japanese Patent No. 3359314

  The above-described light-shielding photographing is generally performed before and after the main photographing. For example, when light-shielded shooting is performed before actual shooting, there is a time lag from the release button operation until main shooting is performed, and even if the release button is operated at the timing that the user intends, the actual gain can be obtained. The actual image to be displayed does not have the composition intended by the user. Conversely, when light-shielding shooting is performed after main shooting, it is not suitable for continuous shooting or shooting with long exposure. In particular, in the case of shooting with long exposure, light-shielding shooting is performed with the same exposure time as the main shooting, but the exposure of the image sensor during the long exposure is higher than at the start of shooting. Since light-shielded shooting is performed under different conditions, it is not possible to acquire a main image from which dark current noise has been appropriately removed.

  It is an object of the present invention to provide an electronic camera that can appropriately remove dark current noise from an image obtained by actual photographing.

  In order to solve the above-described problems, an electronic camera of the present invention has an effective pixel area in which pixels that photoelectrically convert subject light into signal charges are two-dimensionally arranged, and the pixels arranged in the effective pixel area A setting unit that divides and sets the effective pixel region into a plurality of regions such that any two or more pixels include an image sensor including a light-shielded pixel that blocks the subject light, and the light-shielded pixel. And a correction unit that corrects the pixel values of the pixels included in the region for each region based on the pixel values of the light-shielding pixels included in the region divided and set by the setting unit during imaging by the imaging device. , Provided.

  Note that the light-shielding pixels are preferably arranged discretely with respect to the effective pixel region.

  The effective pixel area of the image sensor is generated based on multiple exposures, and the setting unit divides the effective pixel area based on each exposure range in the multiple exposures. Is preferred.

  In addition to this, it is preferable that the setting unit sets a central region of the effective pixel region and other regions as divided regions.

  In addition, it is preferable that a large number of the light-shielding pixels be arranged near the boundary between adjacent regions when the effective pixel region is divided into a plurality of regions.

  Further, the correction unit obtains correction values for the pixel values of all the pixels included in the region by performing a fitting process using the pixel values of the light-shielding pixels included in each of the regions. It is preferable to correct the pixel value of each pixel obtained at the time of imaging using this correction value.

  The imaging device further includes a light-shielding pixel region that shields the subject light from the periphery of the effective pixel region, and the correction unit includes a pixel value of the light-shielding pixel included in each region. Preferably, the pixel value of the pixel included in each of the divided regions is corrected using the pixel value of the pixel included in the light-shielding pixel region.

  Moreover, it is preferable that the image processing apparatus further includes an interpolation processing unit that interpolates the pixel value of the light-shielded pixel using the pixel value of the peripheral pixel of the light-shielded pixel.

  According to the present invention, dark current noise can be appropriately removed from an image obtained by actual photographing.

It is a figure which shows the outline of the digital camera which implemented this invention. It is a figure which shows the effective pixel area | region formed by multiple times of exposure. It is a figure which shows the cross section of an image pick-up element. It is a figure which shows an example of arrangement | positioning of a color filter and a light shielding filter. It is a flowchart which shows the flow of a process inside a digital camera at the time of imaging | photography. It is a figure which shows the case where an effective pixel area | region is divided | segmented into two divided areas of the divided area which consists of a center area | region, and the divided area which consists of the area | region of a peripheral edge. It is a figure which shows the cross section of an image pick-up element at the time of producing | generating a light shielding pixel by closing the upper surface of the opening part provided in a light shielding film. It is a figure which shows each division area in the case of the image pick-up element provided with the light-shielding pixel area other than the effective pixel area.

  FIG. 1 shows an example of a digital camera 10 using the present invention. As is well known, the digital camera 10 photoelectrically converts the subject light captured by the imaging optical system 15 by the imaging element 16 and acquires image data based on the electrical signal (image signal) after the photoelectric conversion. The imaging optical system 15 includes a lens group including a zoom lens, a focus lens, and the like that are not shown. These zoom lens and focus lens are moved in the direction of the optical axis L by a lens driving mechanism (not shown).

  The image pickup device 16 is configured by, for example, a charge coupled device (CCD), a complementary metal-oxide semiconductor (CMOS), or the like. Hereinafter, a case where a CCD is used as the imaging element 16 will be described. The image sensor 16 is manufactured by performing divided exposure in which a plurality of exposures are performed while shifting an exposure region in a semiconductor manufacturing facility such as a stepper. FIG. 2 shows a case where the effective image area 21 formed on the imaging surface of the imaging element 16 is formed by performing exposure three times. The effective pixel area 21 is an area necessary for image formation. Reference numerals 22, 23, and 24 in FIG. 2 indicate exposure ranges in the respective exposures.

  As shown in FIG. 3, in the image sensor 16, light receiving elements 26 such as photodiodes are arranged in a matrix on the upper surface of a semiconductor substrate 27. In addition to the light receiving element 26, the semiconductor substrate 27 is provided with a transistor (not shown), a gate portion, a vertical transfer portion, a horizontal transfer portion, an output amplifier, and the like.

  A light shielding curtain 28 is provided on the upper surface of the semiconductor substrate 27 on which the light receiving elements 26 are arranged. The light shielding film 28 is formed in a lattice shape in which upper portions of the light receiving elements 26 provided on the semiconductor substrate 27 are opened. By opening the light receiving element 26, subject light that has passed through each microlens of the microlens array 30 is condensed on each light receiving element 26 via a color filter array 29 described later. A color filter array 29 is provided on the upper surface of the light shielding film 28.

  As shown in FIG. 4, in the color filter array 29, an R color filter 29a, a G color filter 29b, and a B color filter 29c are arranged in a known Bayer array. The light shielding filter 29d is discretely arranged at the position where the G color filter is arranged among the color filters arranged by the Bayer arrangement. In FIG. 4, the light shielding filter 29 d is indicated by “OB (Optical Black)”. For example, when the number of pixels in the effective pixel area 21 of the image sensor 16 is 24 Mpixels in the x direction of 6000 × 4000, the light shielding filters 29d are arranged at 12 pixel intervals in the x direction and the y direction, respectively. For example, when the light shielding filter 29d is disposed at the position of (x, y) = (2, 3), with reference to the light shielding filter 29d, (x, y) = (14, 3), (x, y) = (2,15), (x, y) = (14,15),... On the upper surface of the color filter array 29, a microlens array 30 including a plurality of microlenses arranged in association with the color filter and the light shielding filter described above is provided.

  When subject light is irradiated to such an image pickup device 16, the subject light is collected by each microlens of the microlens array 30 and irradiated to the color filter array 29. At this time, color separation is performed into one of R color light, G color light, and B color light. The color-separated light is applied to the light receiving elements 26 and is photoelectrically converted by the respective light receiving elements 26. On the other hand, of the subject light that has passed through the microlens array 30, light that has reached the light shielding filter 29d is absorbed by the light shielding filter 29d. For this reason, the light-receiving element 26 located at a position corresponding to the light-shielding filter 29d cannot receive the subject light that has passed. In the light receiving element 26 where the subject light is shielded by the light shielding filter 29d, signal charges of noise components generated within the same time as the light receiving time of the other light receiving elements 26 that receive the subject light are accumulated.

  In the following description, the light receiving element 26 that receives the R light separated by the R color filter 29a is an R pixel, the light receiving element 26 that receives the G light separated by the G color filter 29b is a G pixel, and B The light receiving element 26 that receives the B light color-separated by the color filter 29c is referred to as a B pixel, and the light receiving element 26 that blocks the subject light by the light blocking filter 29d is referred to as a light shielding pixel. Further, the signal charge amount output from each pixel will be described as a pixel value. The signal charge of each pixel is output to an AFE (Analog Front End) circuit 36 as an image signal through an output amplifier. When CMOS is used as the image sensor 16, the AFE circuit 36 may be provided inside the image sensor 16.

  Returning to FIG. 1, the driver 35 controls the driving of the image sensor 16. Controlling the driving of the image sensor 16 includes controlling the accumulation of signal charges in each pixel of the image sensor 16 and the output of the accumulated signal charges. Hereinafter, the signal charge output from the image sensor 16 will be described as an image signal. In addition, the driver 35 controls whether to drive all the pixels of the imaging device 16 or some of the pixels. In other words, the image signal is acquired by driving all the pixels of the image sensor 16 at the time of shooting, and the image signal is acquired by so-called thinning control that selectively uses a part of the pixels of the image sensor 16 at the time of non-shooting.

  The AFE circuit 36 includes an AGC circuit and a CDS circuit (not shown). The AFE circuit 36 performs analog processing such as gain control and noise removal on the input image signal, and then converts the analog signal into a digital signal by an A / D conversion circuit (not shown). The digital image signal is output to the DFE circuit 37.

  A DFE (Digital Front End) circuit 37 performs noise correction processing and defect correction processing on the input image signal. The DFE circuit 37 has functions of a noise correction unit 38 and a defect correction unit 39. Note that the functions of the noise correction unit 38 and the defect correction unit 39 do not need to be provided in the DFE circuit 37, and may be provided as a function of the image processing circuit 42, for example.

  The noise correction unit 38 performs noise correction processing such as fitting calculation processing, dark current noise value calculation processing for each pixel, and subtraction processing for the pixel value of each pixel. This noise correction process is executed for each divided area described later.

  As is well known, the fitting calculation process is a calculation process for obtaining an approximate straight line or approximate curve such as the shape and distribution state of the object surface, for example. In the present embodiment, by performing this fitting calculation process, an approximate straight line or an approximate curve indicating the dark current noise distribution state is calculated. As described above, since the light-shielded pixel is a pixel in which the subject light is shielded, the pixel value of the light-shielded pixel is a value of a dark current component (hereinafter, dark current noise). Further, the position coordinates of the light-shielding pixels may be stored in the built-in memory 53 in advance.

  For example, in this fitting calculation process, the following equation (1) is used.

f (x, y) = k ₁ x ³ + k ₂ x ² y + k ₃ x ² + k ₄ xy ² + k ₅ xy + k ₆ x + k ₇ y ³ + k ₈ y ² + k ₉ y + k ₁₀ (1)
Here, f (x, y) is the pixel value of the light-shielded pixel, and x and y are the x coordinate and y coordinate in the effective pixel region. After substituting the position coordinates and pixel values of these light-shielding pixels into the above-described equation (1), the coefficients k _{1 to} k ₁₀ are obtained by using, for example, the least square method, so that the dark current noise distribution state is determined. An approximate straight line or an approximate curve is obtained.

  The calculation process of the dark current noise value in each pixel is a process of substituting the position coordinates of each pixel into the approximate straight line or approximate curve obtained by performing the above-described fitting calculation process, and obtaining the dark current noise value in the pixel. is there.

  The subtraction process for the pixel value of each pixel is a process of subtracting the pixel value of the corresponding pixel using the calculated dark current noise value. By executing this subtraction process for each pixel, an image signal from which dark current noise has been removed is acquired.

  The defect correction unit 39 performs defect correction processing on the image signal from which dark current noise has been removed. This defect correction process is, for example, a process for pixels such as white spots and the above-described light-shielded pixels. For example, a pixel such as a white point has a higher pixel value than the pixel value of other pixels, so the threshold value is set by calculating the pixel value of the pixel that is the white point in advance through statistics or experimentation. To do. The defect correction unit 39 identifies a pixel having a pixel value higher than the threshold value as a defective pixel among all the pixels. In the case of a light-shielded pixel, the position information of these pixels is stored in the built-in memory 53, and the position information is referred to. The light-shielded pixel specified from this position information is specified as a defective pixel.

  After identifying these defective pixels, the defect correction unit 39 replaces the pixel value of any pixel of the same color pixel located at the periphery of the defective pixel with the pixel value of the defective pixel, or is positioned at the periphery of the defective pixel. The average of the pixel values of the same color pixels is replaced with the pixel value of the defective pixel. When the light-shielded pixel is a defective pixel, the position where the light-shielded pixel is arranged is specified after specifying whether the position is the R color, G color, or B color pixel on the Bayer array. The extracted pixels may be extracted from the periphery of the defective pixel.

  The image signal that has been subjected to the defect correction process described above is recorded as RAW data in the buffer memory 41. Reference numeral 40 denotes a timing generator (TG), and the TG 40 is provided to control the drive timing of the driver 35, the AFE circuit 36, and the DFE circuit 37.

  The image processing circuit 42 performs image processing such as white balance processing, color interpolation processing, contour compensation processing, and gamma processing on the RAW data stored in the buffer memory 41. After these processes, the image processing circuit 42 performs a compression encoding process using a preset compression rate. By executing this compression encoding process, for example, JPEG compressed image data is generated. Further, the image processing circuit 42 generates thumbnail image data by performing resolution changing processing.

  In the media slot 44, a storage medium 45 such as a memory card, an optical disk, or a magnetic disk is detachable. The storage medium 45 can record image files such as still images and moving images. For example, if the image file is based on a still image, in addition to the compressed image data and thumbnail image data generated by the image processing circuit 42, there is one piece of information indicating the shooting conditions at the time of shooting and information of the digital camera 10. It consists of Exif format image files compiled in

  The LCD 46 is a form of a display device, and displays a through image and an image obtained at the time of shooting. In addition, the LCD 46 displays an image for setting when the digital camera 10 is set. Reference numeral 47 denotes a display control circuit that performs drive control of the LCD 46.

  The CPU 51 is electrically connected to the buffer memory 41, the image processing circuit 42, the media slot 44, the display control circuit 47, the built-in memory 53, and the like via the bus 52. The CPU 51 controls each part of the digital camera 10 by executing a control program (not shown) stored in the built-in memory 53. A release button 54, a setting operation unit 55, and the like are connected to the CPU 51. The CPU 51 controls each unit of the digital camera 10 based on operation requests and control programs on these operation members.

  The CPU 51 has a function as the setting unit 55 by executing the control program described above. The setting unit 55 sets a plurality of areas (hereinafter referred to as divided areas) obtained by dividing the effective pixel area 21. The built-in memory 53 stores in advance exposure information indicating an exposure range in each of a plurality of exposures. The setting unit 55 reads the exposure information described above from the built-in memory 53, thereby executing the above-described setting of the divided areas. Thereby, each divided area is set in accordance with an exposure range in a plurality of exposures performed at the time of manufacture. As shown in FIG. 2, when an effective pixel region is generated by three exposures, the exposure ranges in these exposures (regions 22, 23, and 24 in FIG. 2) are divided regions. When the divided areas are set, the setting unit 55 outputs address data indicating each divided area to the image processing circuit 42. Thereby, image correction for each divided region is executed.

  Hereinafter, the setting of the divided area by the setting unit 55 will be described when it is executed in response to the execution of the imaging process. However, the setting of the divided area by the setting unit 55 is performed at the time of shipment of the digital camera 10 or digitally. You may perform at the time of the starting process performed when the main power supply of the camera 10 is turned on.

  Next, the flow of processing inside the digital camera 10 at the time of shooting will be described based on the flowchart of FIG. The flowchart in FIG. 5 is executed when the digital camera 10 enters a shooting standby state.

  Step S101 is processing for determining whether or not the release button 54 has been operated. When the release button 54 is operated, the operation signal is input to the CPU 51. The CPU 51 determines whether or not an operation signal from the release button 54 has been input. If the CPU 51 determines that the operation signal from the release button 54 has been input, the determination process in step S101 is Yes, and the process proceeds to step S102. On the other hand, when the CPU 51 determines that the operation signal from the release button 54 is not input, the determination process in step S101 is No. In this case, the shooting standby state is continued until the determination process in step S101 is Yes.

  Step S102 is an imaging process. Since the imaging process is well known, the details are omitted here. By performing this imaging process, an image signal is output from the imaging element 16. This image signal is input in the order of the AFE circuit 36 and the DFE circuit 37. Thereby, the analog image signal output from the image sensor 16 is converted into a digital image signal.

  Step S103 is processing for setting a divided area. The CPU 51 reads out exposure information from the built-in memory 53 and sets a divided area. After this setting, the CPU 51 outputs address data indicating each divided area to the DFE circuit 37. Hereinafter, the processing from step S104 to step S107 is noise correction processing.

Step S104 is a fitting calculation process. By executing the processing in step S103, the address data for each divided area is input to the image processing circuit. In response to this, the DFE circuit 37 reads the position information of the light-shielded pixels stored in the built-in memory 53 and then executes a fitting operation for each divided region. As shown in FIG. 2, when the effective pixel region 21 is generated by three exposures, the exposure regions 22, 23, and 24 in each exposure are set as divided regions. First, of the set divided areas, a fitting operation is performed on the left divided area in the figure. As described above, the fitting calculation process is executed using the above-described equation (1) and the position coordinates and pixel values of the light-shielded pixels included in the corresponding divided area. Thereby, the values of the coefficients k _{1 to} k ₁₀ shown in the equation (1) are calculated, and an approximate straight line or an approximate curve indicating the distribution of dark current noise generated in the divided areas is obtained.

  Step S105 is processing for calculating a dark current noise value in each pixel of the divided area. In step S104, an approximate straight line or an approximate curve indicating the distribution of dark current noise is obtained. The image processing circuit 42 calculates the dark current noise value in the target pixel by substituting the position coordinates of each pixel into the obtained approximate straight line or approximate curve. These values are stored in the buffer memory 41, for example. Note that the calculated dark current noise value is recorded in association with the obtained pixel (specifically, position coordinates).

  Step S106 is processing for determining whether or not dark current noise values for all the divided regions have been calculated. If dark current noise values have been calculated for all the divided areas, the determination in step S106 is Yes, and the process proceeds to step S107. On the other hand, when the dark current noise value is calculated only for one of the divided areas, the determination in step S106 is No, and the process returns to step S104. In this case, the processes in step S104 and step S105 are repeatedly executed until the dark current noise values in the pixels included in all the divided areas are calculated.

  Step S107 is a subtraction process for the pixel value of each pixel. When the process of step S107 is executed, the dark current noise values for all the pixels in the effective pixel region are calculated, that is, the processes of step S104 and step S105. The DFE circuit 37 corrects the input image signal using these dark current noise values. That is, the corresponding dark current noise value is subtracted from the pixel value of each pixel. Thereby, an image signal from which dark current noise is removed is obtained.

  Step S108 is processing for executing defect correction processing. The DFE circuit 37 executes defect correction processing on the image signal from which dark current noise has been removed. For example, among the pixel values of each pixel based on the image signal, a pixel having a pixel value exceeding a preset threshold is specified as a defective pixel. In addition, the DFE circuit 37 reads out the position information stored in the built-in memory 53, thereby specifying the light-shielded pixel in the effective pixel region 21 as a defective pixel. Then, the DFE circuit 37 performs a defect correction process on the pixel specified as the defective pixel. As the defect correction processing, when the light-shielded pixel is arranged at the position of the G color pixel in the Bayer array, the average of the pixel values of the G color pixels adjacent to the light shield pixel is obtained to obtain the pixel value of the light shield pixel. For example, the pixel value of any of the adjacent G color pixels may be used as the pixel value of the light-shielded pixel as it is. Note that the image signal subjected to the defect correction processing is recorded as RAW data in the buffer memory 41.

  Step S109 is processing for executing image processing. The image processing circuit 42 performs image processing such as white balance processing, a color interpolation processing unit, contour compensation processing, and gamma processing on the RAW data stored in the buffer memory 41. After these processes, the image processing circuit 42 performs a compression encoding process using a preset compression rate, and generates, for example, JPEG compressed image data. In addition, thumbnail image data is generated by performing resolution changing processing.

  Step S110 is processing for recording an image file. In addition to the compressed image data and thumbnail image data generated in step S <b> 109, the CPU 51 writes an image file in which information indicating shooting conditions and information such as a camera model are collected in the storage medium 45. When this process ends, one shooting is completed.

  In the present invention, since the light-shielding pixels are discretely arranged in the effective pixel region, the image data and the value of the dark current noise can be acquired simultaneously at the time of shooting. In addition, by performing the fitting calculation using the acquired dark current noise value and the position coordinates of the light-shielded pixels, it is possible to obtain an approximate straight line or an approximate curve indicating the dark current noise distribution state. The value of the dark current noise of each pixel can be calculated. According to this, as in the prior art, it is not necessary to perform the light-shielded photographing in which the subject light is shielded before and after the main photographing for photographing by receiving the subject light. According to this, it is possible to solve the drawbacks such as the occurrence of a time lag with respect to the main shooting and the inability to continuously perform the main shooting. In the present invention, since the image data and the dark current noise value can be acquired in the same environment, the dark current noise can be appropriately removed from the image data obtained by photographing.

  In the case of an image sensor generated by a plurality of exposures, the divided areas are set in accordance with the exposure range at the time of exposure. That is, in an image sensor generated by a plurality of exposures, characteristics such as light reception characteristics and output characteristics may be different for each exposure range in each exposure. If the characteristics differ for each exposure range, for example, in an image obtained by imaging a single color wall, the pixel value of the pixel at the boundary of the adjacent exposure range is caused by the difference in the characteristics. Will result in a step. For this reason, by setting each exposure range as a divided area, it is possible to grasp the distribution state of dark current noise in each divided area, and as a result, dark current noise can be appropriately removed. According to this, it is possible to acquire image data in which the occurrence of a step at the boundary between adjacent exposure ranges described above is suppressed and dark current noise is appropriately removed.

  Furthermore, as an arrangement example of the light shielding filter 29d in the color filter array 29, when the number of pixels in the effective pixel region 21 of the image sensor 16 is 24 Mpixels in the x direction of 6000 × 4000, 12 pixels in each of the x direction and the y direction. Takes an example of being arranged at intervals. By disposing the light shielding filter 29d in this way, pixels other than the light shielding pixels can be used in, for example, a through image display (so-called live view display) or a thinning process used in moving image shooting. Can be read.

  In the present embodiment, the divided areas are set in accordance with each exposure range when performing multiple exposures, but it is not necessary to limit to this. As shown in FIG. 6, for example, the characteristics of the pixels arranged in the peripheral region 61 of the effective pixel area 21 may be different from the characteristics of the pixels arranged in the region 62 near the center. In such a case, it is also possible to set from two regions, a region near the center of the effective pixel region 21 and a region at the peripheral edge of the effective pixel region 21.

  Further, depending on the environmental conditions around the image sensor 16 attached to the digital camera 10, some pixels included in the effective pixel region 21 may have different characteristics from the remaining pixels. The environmental conditions around the image sensor 16 include, for example, the environmental temperature around the image sensor 16. In this case, it is also possible to provide a temperature sensor in the image sensor 16 or in the vicinity thereof, and set the divided areas according to the environmental temperature detected by the temperature sensor.

  In the present embodiment, an example in which the color filters of the R color filter 29a, the G color filter 29b, and the B color filter 29c in the color filter array 29 are arranged in a Bayer arrangement is described as an example. It is not necessary to be limited to.

  In the present embodiment, the light shielding filter 29d is disposed at a position where the G color filter 29b of the color filter array 29 arranged in the Bayer array is disposed, and the light shielding filter 29d is disposed for 12 pixels in the x direction and the y direction, respectively. However, the present invention is not limited to this, and may be arranged at intervals other than every 12 pixels, or intervals between adjacent light shielding filters may be different from each other. In addition to this, at least two or more adjacent filters may each be a light shielding filter. In addition, the light shielding filter 29d may be disposed at a position where the R color filter 29a or the B color filter 29c is disposed, in addition to the position where the G color filter 29b is disposed. . Furthermore, it is also possible to arrange more light-shielding pixels, for example, near the boundary between adjacent divided regions than in other locations.

  In the present embodiment, a case where a light shielding filter is used for a color filter array used for one image sensor is described. However, the present invention is not limited to this. For example, R, G, and B color images are used. In the case where three image sensors that individually acquire data are provided, the above-described light-shielded pixels can be arranged in a color filter array used in any one of the image sensors.

  In this embodiment, the light shielding pixels are formed by disposing the light shielding filter 29d at the position where the G color filter 29b of the filter array arranged in the Bayer array is disposed. However, the present invention is not limited to this. Instead of the light shielding filter, as shown in FIG. 7, the opening portion 66 of the light shielding film 28 located on the upper surface of the light receiving element 26 (reference numeral 66 in the figure) or the opening portion 66 itself may be shielded by the covering member 65. Good.

  Although not shown, for example, an opening 66 formed in the light-shielding film 28, an image sensor provided with a light-shielding shutter on the upper surface of the light-receiving element 27, or the like, instead of a color filter array, G color, B It is also possible to use an image pickup device using a liquid crystal panel or an EL panel capable of displaying any one of color and BK (black) color. In the case of using a liquid crystal panel or an EL panel, in addition to the image sensor in which these panels are incorporated, it is also possible to separately arrange these panels and an image sensor that does not include a color filter array.

  For example, when a shutter is provided on the upper surface of the light receiving element 26, the position of a pixel serving as a light-shielded pixel may be changed depending on the shooting mode and shooting conditions at the time of shooting. In this case, when shooting using long exposure, control is performed so that some shutters are closed so that any of the pixels included in the effective pixel region 21 is a light-shielded pixel. When shooting with a short exposure time, all the shutters may be opened so as not to arrange the light-shielding pixels.

  In the present embodiment, the image pickup device 16 in which only the effective pixel region 21 is formed is described. However, the present invention is not limited to this, and as shown in FIG. The imaging element 16 may be provided with the light-shielding pixel regions 72 and 73 including light-shielding pixels that shield light. In this case, the divided region is set by dividing the effective pixel region 21 in accordance with the exposure range, that is, by dividing the effective pixel region 21 by the straight lines L1 and L2. Since the light-blocking pixel area 72 is adjacent to the left-side divided area, the divided area 74 is divided into two areas: a divided area 74 near the light-shielded pixel area and the other divided areas 75. Similarly, since the light-shielded pixel area 73 is adjacent to the right divided area, the divided area 76 is divided into two areas: a divided area 76 in the vicinity of the light-shielded pixel area and another divided area 77. . In this case, for the divided region 74 adjacent to the light-shielded pixel region 72, the pixel value of the pixel included in the light-shielded pixel region 72 is used, and for the divided region 75 adjacent to the light-shielded pixel region 73, the light-shielded pixel. It is also possible to perform dark current noise removal using the pixel values of the pixels included in the region 73 and perform the noise removal processing of the present invention on the other divided regions 75, 77, 78.

  In the present invention, a digital camera is taken as an example, but it can also be used for a portable terminal such as a mobile phone having a camera function or a portable game device. In addition, an image processing apparatus having the functions of the noise correction unit 38, the defect correction unit 39, and the setting unit 55 shown in FIG. 1 and the function of performing the processing of the flowchart of FIG. In this case, the image processing apparatus performs image processing on the RAW data. However, it is only necessary to add the position information of the light-shielded pixels as the incidental information of the RAW data.

  In addition, the program may be a program for executing the functions of the noise correction unit 38, the defect correction unit 39, and the setting unit 55 shown in FIG. 1, or the processing of the flowchart of FIG. Note that this program is preferably stored in a computer-readable storage medium such as a memory card, an optical disk, or a magnetic disk. In this case, the computer can be used as an image processing apparatus by installing this program in the computer.

  DESCRIPTION OF SYMBOLS 10 ... Digital camera, 16 ... Image sensor, 37 ... DFE circuit, 38 ... Noise correction part, 39 ... Defect correction part, 41 ... Buffer memory, 42 ... Image processing circuit, 51 ... CPU, 55 ... Setting part

Claims (8)

A pixel that photoelectrically converts subject light into signal charge has an effective pixel region that is two-dimensionally arranged, and any two or more of the pixels disposed in the effective pixel region are shielded from shielding the subject light. An image sensor consisting of pixels;
A setting unit configured to divide and set the effective pixel region into a plurality of regions such that the light-shielding pixels are included in each region;
A correction unit that corrects the pixel value of the pixel included in the region for each region based on the pixel value of the light-shielding pixel included in the region divided and set by the setting unit during imaging by the imaging device;
An electronic camera characterized by comprising: The electronic camera according to claim 1,
The electronic camera, wherein the light shielding pixels are discretely arranged with respect to the effective pixel region. The electronic camera according to claim 1 or 2,
The effective pixel area of the image sensor is generated based on a plurality of exposures,
The electronic camera according to claim 1, wherein the setting unit divides the effective pixel area based on each exposure range in the plurality of exposures. The electronic camera according to claim 1 or 2,
The electronic camera according to claim 1, wherein the setting unit sets a central region of the effective pixel region and other regions as divided regions. The electronic camera according to any one of claims 1 to 4,
The electronic camera according to claim 1, wherein a large number of the light-shielding pixels are arranged near a boundary with an adjacent region when the effective pixel region is divided into a plurality of regions. The electronic camera according to any one of claims 1 to 5,
The correction unit obtains correction values for the pixel values of all pixels included in the region by performing a fitting process using the pixel values of the light-shielded pixels included in each of the regions, and performs correction for each obtained pixel. An electronic camera characterized by correcting a pixel value of each pixel obtained at the time of imaging using a value. The electronic camera according to any one of claims 1 to 6,
The imaging device further includes a light-shielding pixel region where the subject light is shielded at a peripheral portion of the effective pixel region,
The correction unit corrects the pixel value of each pixel included in each of the divided regions using the pixel value of the pixel included in the light-shielded pixel region in addition to the pixel value of the light-shielded pixel included in each region. An electronic camera characterized by The electronic camera according to any one of claims 1 to 7,
An electronic camera, further comprising: an interpolation processing unit that interpolates the pixel value of the light-shielded pixel using a pixel value of a peripheral pixel of the light-shielded pixel.

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