Imaging apparatus

Abstract

To make it possible to correct defective pixels even when a circuit for amplifying pixel signals is switched depending on the shooting mode of an imaging apparatus.SOLUTION: When defective pixels are corrected in the outputs of a first amplifier circuit and a second amplifier circuit that amplify the same pixel signal with a plurality of different gains, at least one defect correction value is selected according to the circuit that performs amplification.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an imaging device. [Background technology]

[0002] Conventionally, a technique has been proposed for expanding the dynamic range of gradation by amplifying the signal from the same pixel with different gains using imaging elements such as CCD image sensors and CMOS image sensors used in general digital cameras.

[0003] For example, the imaging device of Patent Document 1 discloses a technique for amplifying and outputting an output signal of the same pixel with different gains by a plurality of column circuits. The imaging device of Patent Document 2 includes a floating diffusion (hereinafter, FD) section that converts a signal charge transferred from a photoelectric conversion section into a voltage, and an FD extension section for expanding the capacity of the FD section. The imaging device of Patent Document 2 discloses a technique for amplifying and outputting a signal of the same pixel with different gains by switching the FD extension section on and off. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2015-128253 [Patent Document 2] Patent Publication No. 2021-022921 Summary of the Invention [Problem to be solved by the invention]

[0005] As mentioned above, it is possible to amplify the signal of the same pixel output from the pixel section of the image sensor with different gains. The noise component is removed by reading out the optical signal consisting of a noise signal containing noise components and an optical signal component, and subtracting the noise signal from the optical signal. When the noise signal and optical signal are amplified with two gains and read out, it takes longer to read out the signal than with a general readout method.

[0006] Furthermore, as in the techniques described in Patent Documents 1 and 2, defective pixels that occur in a captured image differ depending on the circuit that amplifies the pixel signal, so appropriate correction is required.

[0007] An object of the present invention is to provide an imaging device that can switch a circuit that amplifies a pixel signal depending on shooting conditions, etc., and can correct defective pixels in a captured image regardless of the amplifying circuit. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, the imaging device of the present invention comprises a plurality of pixels that generate pixel signals by photoelectrically converting an optical image of a subject, first and second amplification means that amplify signals of the same pixel among the plurality of pixels, a correction means that corrects a defective pixel in an output signal of the plurality of pixels amplified by at least one of the first and second amplification means, and a selection means that selects at least one correction value from a plurality of correction values ​​to be used by the correction means to correct the defective pixel, wherein the first and second amplification means each amplify the signal of the same pixel among the plurality of pixels with at least one of a plurality of different gains, and the selection means selects at least one from the plurality of correction values ​​depending on the amplification means used when amplifying the signal of the same pixel. Effect of the Invention

[0009] According to the present invention, it is possible to provide an imaging device capable of appropriately correcting defective pixels in a captured image in accordance with the characteristics of a circuit that amplifies pixel signals depending on shooting conditions, etc. [Brief description of the drawings]

[0010] [Figure 1] 1 is a block diagram showing a schematic configuration of an imaging device 100 according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram showing the arrangement of an image sensor 102 according to the embodiment of the present invention. [Diagram 3] FIG. 4 is a diagram showing a scratch correction value according to an embodiment of the present invention. [Figure 4] 4 is a flowchart showing a process for switching an amplifier circuit of an image sensor 102, a process for switching a defect correction value, and a process for correcting a defective pixel according to the first embodiment of the present invention. [Diagram 5] 4 is a diagram showing a flaw correction value table for the amplifier circuit of the image sensor 102 according to the first embodiment of the present invention. [Figure 6] FIG. 10 is a flowchart showing a procedure for additionally correcting a defective pixel according to a second embodiment of the present invention. [Figure 7] 13A and 13B are diagrams showing a defect correction value table and defective pixel correction threshold values ​​for additionally correcting defective pixels according to the second embodiment of the present invention; [Figure 8] FIG. 13 is a flowchart showing a procedure for generating a defect correction value according to a third embodiment of the present invention. [Figure 9] FIG. 13 is a diagram showing a scratch correction value according to the third embodiment of the present invention. [Figure 10] 13A to 13C are diagrams showing a process of correcting defective pixels in an image sensor output 205 according to a fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, the embodiments of the present invention will be described in detail with reference to the attached drawings. Note that the following embodiments do not limit the invention according to the claims. Although the embodiments describe a number of features, not all of these features are essential to the invention, and the features may be combined in any manner. Furthermore, in the attached drawings, the same reference numbers are used for the same or similar configurations, and duplicated descriptions are omitted.

[0012] Example 1 In this embodiment, an example will be described in which defective pixels that occur by switching a circuit that amplifies pixel signals in an image sensor are appropriately corrected.

[0013] FIG. 1 is a block diagram showing a schematic configuration of an imaging device 100 according to an embodiment of the present invention.

[0014] In FIG. 1, a photographing lens 101 is an interchangeable lens unit that can be attached to the main body of the imaging device 100, or a lens section built into the main body, and is made up of a plurality of lens groups such as a focus lens and a zoom lens, an aperture mechanism, and the like.

[0015] The image sensor 102 is a CMOS image sensor having a plurality of pixels, and performs photoelectric conversion at each pixel on the optical image of the subject formed by the photographing lens 101 to generate an electric charge according to the amount of incident light. Furthermore, by outputting pixel signals amplified by a plurality of different gains for pixel signals corresponding to the generated electric charges, it is possible to obtain a plurality of images with different brightnesses in one shooting. The image capturing device 100 according to the embodiment of the present invention has a configuration in which pixel signals are amplified by different circuits, and the circuit for amplifying the pixel signal can be switched depending on the shooting mode and the settings at the time of shooting when shooting with the image capturing device 100.

[0016] The image acquisition unit 103 acquires pixel signals output from the image sensor 102, temporarily holds the acquired pixel signals, and performs photometry using the acquired pixel signals. The image acquisition unit 103 may also be configured to generate correction values ​​necessary for correction processing performed in an image processing unit 105 (described later) based on the acquired pixel signals, and store the generated correction values ​​in a storage unit 108 (described later).

[0017] The image synthesis unit 104 generates an HDR (high dynamic range) image by any synthesis method using an image signal based on the output of the image sensor 102 temporarily stored in the image acquisition unit 103. For example, an image signal multiplied by a high gain is used for image parts below a predetermined signal level, and an image signal multiplied by a low gain is used for image parts above the predetermined signal level (a bright, blown-out image). It is preferable that random noise in the dark areas is suppressed for the normal image used for the signal of the dark areas of the synthesized image. When HDR shooting is not performed, the image signal stored in the image acquisition unit 103 is output as is.

[0018] The image processing unit 105 performs various signal processing such as a process for correcting an output signal of a defective pixel, a gamma correction process, a color signal process, and an exposure correction process on the image signal output from the image synthesis unit 104, and outputs the processed image signal. Note that the various processes performed by the image processing unit 105 may be configured to be processed based on a correction value stored in advance in a storage unit 108 described later, or may be configured to generate a correction value based on an image acquired by the image acquisition unit 103 and perform the correction process.

[0019] The image recording unit 106 records the image signal processed by the image processing unit 105 in a storage device or storage medium. As the storage device or storage medium, for example, a memory device that can be attached to the main body of the imaging device 100 is used.

[0020] By operating the operation unit 107, the user inputs various instructions to the imaging device 100. The operation unit 107 includes operation members such as a release button, a mode switching dial, and a zoom operation lever, a touch panel, etc. The user input via the operation unit 107 is notified to the system control unit 110.

[0021] The storage unit 108 stores instructions given by a user to the imaging device 100. It is also capable of storing defect correction values ​​for correcting defective pixels, and is configured from an electrically erasable and recordable non-volatile memory.

[0022] The display unit 109 is for displaying a captured image, information at the time of capturing an image, a user interface for operation by the operation unit 107, and the like, and is configured, for example, by a TFT-LCD. The display unit 109 may be configured by a touch panel, so that input from a user capable of operating the operation unit 107 can also be input to the display unit 109. Alternatively, the display unit 109 may be configured by an EVF or the like equipped with an eye-gaze input function, so that input from a user capable of operating the operation unit 107 can also be input to the display unit 109.

[0023] The system control unit 110 includes a luminance difference detection unit 110a, a motion detection unit 110b, an exposure control unit 110c, etc. And, based on the image signal and the photometry result held in the image acquisition unit 103, and the input from the user via the operation unit 107, the system control unit 110 controls the image sensor control unit 111 and the lens control unit 112.

[0024] The luminance difference detection unit 110a calculates the luminance difference between the bright area and the dark area by using the image signal held in the image acquisition unit 103. For example, the entire screen is divided into a plurality of areas, the luminance (brightness) is measured for each area, and the luminance difference between the bright area (bright area) and the dark area (dark area) is calculated.

[0025] The motion detection section 110b performs a process of detecting the amount of motion of the subject from the image signal of the current frame held in the image acquisition section 103 and the image signal of the previous frame.

[0026] The exposure control unit 110c calculates the exposure conditions to be used for image capture based on the photometry results obtained by the image acquisition unit 103.

[0027] The image sensor control unit 111 controls the driving of the image sensor 102 in accordance with a control signal from the system control unit 110 .

[0028] The lens control unit 112 controls the driving of the photographing lens 101 in accordance with a control signal from the system control unit 110 .

[0029] Under the control of the system control unit 110 , the defective pixel detection unit 113 detects defective pixels from the image signal of the image recording unit 106 .

[0030] Fig. 2 is a configuration block diagram conceptually showing the configuration of the image sensor 102 in Fig. 1. Hereinafter, the image sensor 102 of the imaging device 100 according to the embodiment of the present invention will be described with reference to Fig. 2.

[0031] Charges accumulated in a photodiode 201 (hereinafter, PD) are amplified with Lo gain 202a or Hi gain 202b in a pixel gain section 202 (first amplifying means) provided in the pixel, and output to a pixel output section 203. For example, the pixel gain section 202 has a function of switching an FD capacitance (not shown), and can reduce a voltage value corresponding to the amount of charge accumulated in the PD 201 (amplify with Lo gain 202a) by increasing the FD capacitance. Similarly, the pixel gain section 202 can increase a voltage value corresponding to the amount of charge accumulated in the PD 201 (amplify with Hi gain 202b) by decreasing the FD capacitance.

[0032] It should be noted that pixel output unit 203 outputs the N signal and the S signal. When the pixel gain unit 202 amplifies with two gains, Lo gain and Hi gain, the N signal and S signal amplified with Hi gain are output first, followed by the N signal and S signal amplified with Lo gain. Therefore, when the pixel gain unit 202 amplifies with two different gains, the signal readout time of pixel output unit 203 becomes longer.

[0033] Next, the analog amplifier 204 (second amplifying means) amplifies the pixel signal output from the pixel output unit 203. In this embodiment, the pixel signal can be amplified with a plurality of different gains by switching the slope of a ramp signal used during AD conversion by an AD converter (not shown). That is, the analog amplifier 204 can amplify the pixel signal with at least one gain of a Lo gain 204a and a Hi gain 204b. The pixel signal amplified by the analog amplifier 204 is output from a sensor output I / F 205 to the outside of the image sensor 102.

[0034] It is known that a characteristic of a general image sensor is that noise occurs in each circuit within the image sensor. Furthermore, when a pixel signal is amplified, the noise is also amplified. For this reason, applying gain at an earlier stage and suppressing the gain at a later stage leads to suppression of noise. Therefore, in the configuration of the embodiment of the present invention shown in FIG. 2, amplification by the pixel gain unit 202 is more advantageous in terms of noise than amplification by the analog amplifier 204.

[0035] Here, when the pixel gain unit 202 of the image sensor 102 has a function of switching the FD capacitance as described above, it is possible that the switching of the FD capacitance may cause the pixel to become defective, with the output signal level of the pixel differing from the original level. In such cases, it is necessary to correct the defective pixel in accordance with the setting of the signal amplification gain in the pixel gain unit 202.

[0036] Fig. 3 is a table explaining the types of defect correction values ​​for correcting defective pixels according to the circuit used to amplify pixel signals. In Fig. 3, column 301 shows table numbers I to IV assigned to the defect correction values, and column 302 shows the use of each defect correction value. In addition, column 303 shows the type of defect correction value, and column 304 shows the number of each defect correction value.

[0037] Table number I is a defect correction value used when a pixel signal is amplified by the pixel gain unit 202. When amplifying by the pixel gain unit 202, if there is a defect in the FD, the defect occurrence state differs depending on whether the FD extension unit is on or off, so it is necessary to have a defect correction value for the Lo gain of the pixel gain unit 202 and a defect correction value for the Hi gain.

[0038] Table number II is a defect correction value used when a pixel signal is amplified by the analog amplifier 204. When amplified by the analog amplifier 204, the signal is multiplied by either Lo gain or Hi gain from the preceding pixel gain unit 202 and output, so table numbers II-i and II-ii have one defect correction value corresponding to each gain of the pixel gain unit 202.

[0039] Table number III is a defect correction value used when the same defect occurs at the Lo gain and Hi gain of the pixel gain unit 202. Defective pixels in which the defect occurs at different locations at the Lo gain and Hi gain using table number I are distinguished by assigning an identifier.

[0040] Table number IV is a defect correction value for correcting the output signal of a defective pixel that has been amplified by a single gain in both the pixel gain unit 202 and the analog amplifier 204 .

[0041] 4 is a flowchart showing a process of switching the circuit used for amplifying pixel signals and a process of correcting output signals of defective pixels depending on the state of the subject. The flowchart in FIG. 4 is started when the system control unit 110 instructs the process of switching the circuit used for amplification and the process of switching the defect correction value.

[0042] In step S401, when the user operates a release button (not shown) or the like included in the operation unit 107 to instruct actual shooting, shooting is performed with an exposure that was determined in advance before the actual shooting. Then, the image signal output from the image sensor 102 is acquired by the image acquisition unit 103, and photometry of the subject image is performed.

[0043] Furthermore, the motion detection unit 110b calculates the amount of motion of the subject, and the brightness difference detection unit 110a calculates the brightness difference between the light and dark areas of the subject, based on the image acquired by the image acquisition unit 103. The image signals acquired at this time may be read out from all the pixels of the image sensor 102, or may be read out by thinning-out readout or additive readout, and are output after being multiplied by a predetermined gain.

[0044] In step S402, a circuit to be used for amplifying the pixel signal is selected from a setting table shown in Fig. 5, which will be described later, according to the evaluation value calculated in step S401. Specifically, the optimum circuit for amplifying the pixel signal is selected according to the amount of motion of the subject calculated by the motion detection unit 110b and the luminance difference calculated by the luminance difference detection unit 110a.

[0045] Here, a method for selecting a circuit to be used for amplification and a method for selecting a defect correction value will be described with reference to Fig. 5. Fig. 5 is a setting table that defines switching settings of a circuit to be used for amplification and defect correction values ​​associated with the switching settings of a circuit to be used for amplification.

[0046] 5, column 501 indicates table numbers A to D assigned to the circuits used for the selected amplification, and column 502 indicates the amount of subject movement and brightness difference calculated in step S401 in Fig. 4. Also, column 503 indicates the settings of the circuits used for the selected amplification.

[0047] For example, when the amount of movement of a subject is large, amplifying the signal with two gains in pixel gain unit 202 extends the signal readout time, which may result in noticeable rolling distortion of the subject. Therefore, when the amount of movement of a subject is large, control is performed so that the signal is amplified with two gains in analog amplifier 204, rather than in pixel gain unit 202.

[0048] Similarly, when the amount of movement of the subject is small, the rolling distortion of the subject is unlikely to become noticeable even if the signal readout time is extended, so control is performed so that the pixel gain section 202 amplifies the signal by two gains.

[0049] Furthermore, when the brightness difference of the subject exceeds a predetermined value, a sufficient dynamic range cannot be ensured by only amplifying in the pixel gain unit 202. In such a case, a wider dynamic range can be ensured by amplifying not only with two gains in the pixel gain unit 202 but also with two gains in the analog amplifier 204.

[0050] In addition, when the amount of movement of the subject is large and the brightness difference of the subject is large, the difference between the two gains in analog amplifier 204 may be controlled to be larger compared to when the amount of movement of the subject is small or the brightness difference of the subject is small.

[0051] Next, in step S403 in Fig. 4, the defect correction value associated with the circuit to be used for amplification selected in step S402 is referenced from among the defect correction values ​​stored in the storage unit 108. Column 504 in Fig. 5 indicates which defect correction value is to be used from among the defect correction values ​​shown in Fig. 3 according to the circuit selected in column 503 in Fig. 5.

[0052] In table numbers A and B, the analog amplifier 204 is used as a circuit for amplifying pixel signals, and the signal is set to be amplified at two gains, but there are no defects that occur due to the amplification characteristics of the analog amplifier 204. Therefore, even when the analog amplifier 204 provides two gain differences, the defect correction value according to the amplification rate setting in the pixel gain unit 202 is associated with the signal.

[0053] That is, in table number A, the amplification factor setting in the pixel gain unit 202 is Lo gain, so table number II-i in Fig. 3 is linked as the defect correction value for correcting the output signal of the defective pixel. Also, in table number B, the amplification factor setting in the pixel gain unit 202 is Hi gain, so table number II-ii in Fig. 3 is linked as the defect correction value for correcting the output signal of the defective pixel.

[0054] Furthermore, in table numbers C and D, the pixel signal is set to be amplified by two gains in the pixel gain unit 202, and therefore the defect correction value is linked to the defect correction value of table number I or III in FIG.

[0055] 4, the image processing unit 105 corrects the output signal of the defective pixel using the defect correction value referenced in step S403. When the defect correction process in step S404 is completed, the series of processes ends.

[0056] With the configuration described above, when the signal from the same pixel among multiple pixels is amplified by at least one of the first amplification means and the second amplification means, appropriate defective pixel correction is possible in accordance with the settings of the circuit that amplifies the pixel signal.

[0057] In this embodiment, an example in which a pixel signal is amplified with two different gains has been described, but the present invention is not limited to two gains. It is also possible to configure the output signal of the same pixel obtained in one shooting to be amplified with three or more different gains to obtain three or more images with different brightness.

[0058] Example 2 In this embodiment, a process will be described for a case where a defect correction value held for a pixel signal amplified with a plurality of gains in an image sensor is different from the characteristics of a circuit used to amplify the pixel signal. That is, when a defective pixel is corrected with a defect correction value different from the characteristics of a circuit used to amplify the pixel signal, a method of correcting an uncorrected defective pixel or a correction mark of a defective pixel by switching a threshold value for defective pixel correction and an example of correction by pixel interpolation will be described.

[0059] Here, the threshold value of defective pixel correction in this embodiment is a threshold value that adjusts the degree of correction processing when correcting defective pixels, and the degree of correction processing for defective pixels can be adjusted by switching the threshold value. Note that since known techniques can be applied to the technique related to the threshold value of defective pixel correction, a description thereof will be omitted here. Similarly, since known techniques can be applied to the technique for correcting defective pixels by pixel interpolation in this embodiment, a description thereof will be omitted here.

[0060] Fig. 6 is a flowchart showing a process of switching the circuit used for amplifying pixel signals and a process of correcting output signals of defective pixels depending on the state of the subject. The flowchart in Fig. 6 starts when the system control unit 110 instructs the switching of the circuit used for amplification and the switching of the defect correction value.

[0061] Step S601 is the same as the process in step S401 in FIG. 4, and therefore a description thereof will be omitted.

[0062] In step S602, the defect correction value stored in the storage unit 108 is referenced.

[0063] In step S603, the image processing unit 105 corrects the output signal of the defective pixel using the defect correction value referenced in step S602.

[0064] In step S604, the image processing unit 105 performs correction on pixel output signals that contain defective pixels or traces of the defective pixel correction, out of the plurality of pixel output signals whose defective pixels have been corrected in step S603.

[0065] Here, a method of correcting an output signal of a defective pixel using a defect correction value different from the setting of the circuit used for amplification will be described with reference to Fig. 7. Fig. 7 shows a setting table that defines a method of selecting a circuit used for amplification and different defect correction values.

[0066] 7, column 701 indicates table numbers C-1 to C-3 assigned to the defect correction values, column 702 indicates the amount of movement and brightness difference of the subject, and column 703 indicates the settings of the circuit used for amplification. Column 704 indicates the defect correction values ​​referenced in step S602 of Fig. 6, and here, a defect correction value different from the settings of the circuit used for amplification in column 703 is linked to it. Furthermore, column 705 indicates how to switch the threshold value for defective pixel correction for pixel output signals that contain defective pixels or traces of defective pixel correction, among a plurality of pixel output signals in which defective pixels have been corrected in step S604 of Fig. 6.

[0067] In table number C-1 in column 701, the defective pixel signal amplified with Lo gain and Hi gain in the pixel gain unit 202 is corrected using a defect correction value for correcting the defective pixel signal amplified with Lo gain in the pixel gain unit 202 described in column 704. Therefore, the defect correction values ​​for correcting the defective pixel signal amplified with Hi gain among the multiple pixel outputs do not match. Specifically, since traces of defective pixel correction remain in the pixel output signal, the threshold value for defective pixel correction is lowered to make the traces of defective pixel correction less visible.

[0068] In table number C-2 in column 701, the defective pixel signal amplified with Lo gain and Hi gain in the pixel gain unit 202 is corrected using a defect correction value for correcting the defective pixel signal amplified with Hi gain in the pixel gain unit 202 described in column 704. Therefore, the defect correction values ​​for correcting the output signal of a defective pixel amplified with Lo gain among multiple pixel outputs do not match. Specifically, a new defective pixel occurs and the uncorrected defective pixel remains in the pixel output signal, so the defective pixel is made invisible by raising the threshold value for defective pixel correction. Note that the defective pixel may be corrected by pixel interpolation processing to make the defective pixel remaining in the pixel output invisible.

[0069] In table number C-3 in column 701, the output signal of a defective pixel amplified with Lo gain and Hi gain in the pixel gain unit 202 is corrected using a defect correction value for correcting the output of a defective pixel amplified with only one gain listed in column 704.

[0070] When the defective pixel is corrected by a defect correction value amplified by only one gain for the output signal of the defective pixel signal amplified by the Lo gain in the pixel gain unit 202, the defect caused by turning on the FD extension unit cannot be corrected and the defective pixel remains as a defective pixel. The remaining defective pixel is made invisible by the same method as table number C-2.

[0071] Next, when a defective pixel signal amplified with Hi gain in the pixel gain unit 202 is corrected with a defect correction value amplified with only one gain, it takes a long time for the pixel output unit 203 to read out the signal. Therefore, the output of the defective pixel increases due to the readout time, making the defective pixel more noticeable. Therefore, the defective pixel is made invisible by correcting the defective pixel by raising the threshold for defective pixel correction.

[0072] With the configuration described above, even if defective pixels with multiple pixel outputs are corrected using a defect correction value that is different from the settings of the circuit used to amplify the pixel signal, it is possible to correct the remaining defective pixels and correction marks of the defective pixels.

[0073] In this embodiment, the process is described in the order of first correcting a defective pixel with the associated defect correction value and then changing the threshold for defective pixel correction again, but it is also possible to change the threshold for defective pixel correction in advance and then correct the defective pixel with the associated defect correction value.

[0074] Example 3 In this embodiment, an example will be described in which a defective pixel is detected from an image captured by switching a circuit that amplifies a pixel signal in an image sensor, and a defect correction value is generated.

[0075] FIG. 8 is a flowchart showing a process for switching the circuit used to amplify pixel signals depending on the state of the subject, and a process for detecting defective pixels and generating a defect correction value, and FIG. 9 is an example of the generated defect correction value.

[0076] The flowchart in FIG. 8 starts when the system control unit 110 issues an instruction to switch the circuit used for amplification and to switch the defect correction value.

[0077] Step S801 is the same as the process in step S401 in FIG. 4, so a description thereof will be omitted.

[0078] Step S802 is the same as the process in step S402 in FIG. 4, and therefore a description thereof will be omitted.

[0079] In step S803, the image signal from the image recording unit 106 is sent to the defective pixel detection unit 113, where defective pixel detection processing is performed. Since the defective pixel detection processing is a known technique, a description thereof will be omitted.

[0080] In step S804, a defect correction value is generated from the defective pixels detected by the defective pixel detection unit 113.

[0081] Next, the defect correction value will be described with reference to FIG.

[0082] Table 900 in FIG. 9 is an example of three defect correction values ​​when the pixel gain unit 202 and the analog amplifier 204 amplify the signal with only one gain each.

[0083] Column 901 is a number indicating the number of defective pixels, and in this case represents the defect correction values ​​for two pixels. In this embodiment, assuming that defective pixels are detected in two pixels, the first defective pixel detection data is "number 1" and the second defective pixel detection data is "number 2." Note that the number of detected defective pixels is not limited to two.

[0084] Column 902 is information about defective pixels detected in step S802 of Fig. 8. Information about a defect for one defective pixel is generated by the X coordinate, Y coordinate, and output value of the defective pixel. This information exists for the number of detected defective pixels, and is collectively used as a defect correction value.

[0085] When the pixel gain unit 202 and the analog amplifier 204 each perform amplification with only one gain, the defective pixel is corrected by the method described in the first and second embodiments using a defect correction value 900 consisting of three items: the X coordinate, the Y coordinate, and the output value of the defective pixel.

[0086] 9 is an example of defect correction values ​​that can be used regardless of whether amplification is performed by the pixel gain unit 202 or the analog amplifier 204. Table 910 in this embodiment differs from table 900 described above in that column 911 is added with information about an identifier indicating whether the defective pixel has been amplified by the pixel gain unit 202 with Lo gain or Hi gain.

[0087] For example, when a defective pixel is corrected using the defect correction value in table 910, the defective pixel numbered 1 in table 912 also has a defect in the output of the pixel gain unit 202 and the analog amplifier 204. Also, the defective pixel numbered 2 has a defect only in the output of the pixel gain unit 202.

[0088] In this way, it is possible to generate a defect correction value that matches the settings of the circuit that amplifies the pixel signal, and by having an identifier such as column 911, it is also possible to combine two types of defect correction values ​​into a single defect correction value.

[0089] Example 4 In this embodiment, an example will be described in which a defective pixel is corrected using an appropriate defect correction value according to the output format of image data output from the sensor output I / F 205 in FIG.

[0090] Fig. 10 is a diagram showing a process for correcting defective pixels in accordance with the output format of the image signal output from the sensor output I / F 205 in Fig. 2. Here, the image signal output from the sensor output I / F 205 is arranged such that pixel signals amplified with a Lo gain and pixel signals amplified with a Hi gain are alternately arranged.

[0091] 10, output data 1001 and output data 1002 are obtained by dividing the image signal output from the sensor output I / F 205 into a pixel signal amplified by a Lo gain and a pixel signal amplified by a Hi gain. Defective pixels in the Lo gain output data 1001 are corrected with a defect correction value for the Lo gain, and defective pixels in the Hi gain output data 1002 are corrected with a defect correction value for the Hi gain.

[0092] The output data 1003 is an image signal output from the sensor output I / F 205 such that pixel signals amplified with a Lo gain and pixel signals amplified with a Hi gain are alternately arranged. In this case as well, defective pixels amplified with a Lo gain are corrected with a defect correction value for the Lo gain, and defective pixels amplified with a Hi gain are corrected with a defect correction value for the Hi gain.

[0093] With this configuration, even in an output format in which pixel signals amplified with a Lo gain and pixel signals amplified with a Hi gain are alternately arranged, defective pixels can be corrected with a defect correction value corresponding to the amplification gain of the output data. Also, even in an output format in which pixel signals amplified with a Hi gain and pixel signals amplified with a Lo gain are distributed, defective pixels can be corrected with a defect correction value corresponding to the amplification gain of the output data.

[0094] Although the present invention has been described in detail based on the preferred embodiments, the present invention is not limited to these specific embodiments, and various forms within the scope of the gist of the present invention are also included in the present invention. Parts of the above-described embodiments may be combined as appropriate.

[0095] (Other embodiments) The present invention can also be realized by supplying a program that realizes one or more functions of the above-mentioned embodiments to a system or device via a network or a storage medium, and having one or more processors in a computer of the system or device read and execute the program.

[0096] It may also be realized by a circuit (eg, ASIC) that realizes one or more functions. [Explanation of symbols]

[0097] 12 Image sensor 13 Signal Processing Section 19 Defective pixel detection section

Claims

1. A plurality of pixels that photoelectrically convert an optical image of a subject to generate pixel signals; First and second amplifying means for amplifying a signal of the same pixel among the plurality of pixels; a correction unit that corrects defective pixels in the output signals of the plurality of pixels amplified by at least one of the first and second amplification units; a selection unit that selects at least one correction value to be used by the correction unit to correct the defective pixel from among a plurality of correction values; the first and second amplifying means each amplify a signal of a same pixel among the plurality of pixels by at least one of a plurality of different gains; The imaging device according to claim 1, wherein the selection means selects at least one of the plurality of correction values ​​in accordance with an amplification means used when amplifying a signal from the same pixel.

2. 2. The image pickup apparatus according to claim 1, wherein the first amplifier amplifies the signal from the same pixel by a pixel gain section within the pixel.

3. 3. The image pickup apparatus according to claim 2, wherein the second amplifying means amplifies the signal from the same pixel by an analog amplifier provided for each column of the plurality of pixels.

4. A storage means for storing the plurality of correction values, 2. The imaging device according to claim 1, wherein the selection means corrects defective pixels in output signals of the plurality of pixels amplified by at least one of the first and second amplification means, based on at least one correction value selected from the plurality of correction values ​​stored in the memory means.

5. 2. The imaging apparatus according to claim 1, further comprising a change unit for changing a threshold value used by said correction unit to correct defective pixels.

6. 2. The imaging device according to claim 1, wherein the correction means corrects defective pixels in accordance with an output format of a signal amplified at a plurality of different gains by at least one of the first amplification means or the second amplification means.

Images