JP2008053812A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging apparatus capable of executing linearity correction for a light receiving quantity of RAW data (digital data) in an outdoor light without providing a dedicated illumination device. <P>SOLUTION: In executing linearity correction, a CPU 12 moves an imaging lens 18 from a focusing position to perform defocus operation, and changes an electronic shutter speed of a CCD image sensor 16 to gradually change the light receiving quantity. The CPU 12 obtains a difference quantity between predetermined pixel data of the RAW data generated in each light receiving quantity via an analog signal processing section 29 and an ideal straight line, and creates an LUT 15b for linearity correction having corresponding relation between the pixel data and the difference quantity in an EEPROM 14. A linearity correction processing circuit 37 corrects the RAW data on the basis of the LUT 15b for linearity correction. Defocusing enables to execute linearity correction in outdoor light having an unstable light quantity. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an imaging apparatus that digitizes and records an imaging signal, and more particularly, to a correction technique for linearizing the relationship between the level of a digitized imaging signal and the amount of received light.

2. Description of the Related Art Digital cameras that convert subject light imaged by a solid-state imaging device such as a CCD image sensor into digital image data and record it on a recording medium such as a memory card have become widespread. In a digital camera, an image signal output from a solid-state image sensor is subjected to analog signal processing such as gain adjustment and then digitized by an A / D converter. (Referred to as data), the linearity with respect to the amount of received light is impaired by the circuit characteristics of the charge-voltage converter (output circuit), the analog signal processing circuit, and the A / D converter in the solid-state imaging device. In view of this, the present applicant changed the received light amount (accumulated charge amount) received by the solid-state imaging device in a plurality of stages by controlling the light receiving time in Patent Document 1, and digitized pixel data output from a specific pixel and It has been proposed that a difference amount from an ideal straight line is obtained and correction is performed using this difference amount as linearity correction data.
Japanese Patent Application No. 2005-212717

  However, in order to implement the correction method of Patent Document 1, a device for irradiating a solid-state image sensor with a certain amount of light is required. This correction is assumed to be performed in the final inspection process at the manufacturer, and it is not preferable to perform the correction on the user side under the external light. On the other hand, in Patent Documents 2 and 3, a dedicated illumination device is incorporated in the imaging device so that correction can be performed on the user side. However, incorporating the illumination device in this way increases the cost and size of the imaging device. Since it invites, it is not preferable.

  The present invention has been made in view of the above-described problem, and can perform linearity correction related to the amount of received light of RAW data (digital data) under outside light without providing a dedicated illumination device. An object is to provide an apparatus.

  In order to achieve the above object, an image pickup apparatus according to the present invention includes an image pickup unit that converts a signal charge generated by a plurality of two-dimensionally arranged photoelectric conversion elements into an image pickup signal by a charge voltage converter, and the image pickup unit. Including an imaging lens for condensing incident light, a digital data conversion unit for performing predetermined processing on the imaging signal output from the imaging unit and converting it to digital data, and a light receiving amount of the imaging unit including a light shielding state The received light amount control means for changing in a plurality of stages, the predetermined pixel data included in the digital data generated for each received light amount set by the received light amount control means, the light shielding state and the predetermined exposure state, Correction data calculation for calculating a linearity correction data in which a difference amount from the ideal straight line obtained from the pixel data in the pixel is related to the difference amount and the pixel data Means, correction processing means for correcting the digital data based on the linearity correction data, driving the imaging lens, defocusing by moving the imaging lens from a focus position, and controlling the amount of received light A correction control means for operating the correction data calculating means and the correction processing means.

  The correction data calculation means preferably calculates the pixel data for the received light amount not set by the received light amount control means by linear interpolation.

  The imaging unit is also applied to an apparatus including a plurality of the charge-voltage converters for outputting imaging signals in parallel, and the correction data calculation unit is configured to correct the linearity for each of the charge-voltage converters. Preferably, the correction processing means corrects the digital data corresponding to each of the charge-voltage converters using the linearity correction data calculated for each of the charge-voltage converters. .

  Further, the imaging means includes a horizontal transfer path that horizontally transfers the signal charge read from the photoelectric conversion element and vertically transferred to the charge-voltage converter, and the charge-voltage conversion is provided in the horizontal transfer path. When the correction control means performs a correction operation, the horizontal transfer path uses the charge voltage read from the same photoelectric conversion element in time series as the charge transfer voltage. It is preferable to distribute to the converter.

  The imaging means includes a plurality of horizontal transfer paths for horizontally transferring the signal charges read from the photoelectric conversion elements and vertically transferred to the charge voltage converter, and the signal charges read from the photoelectric conversion elements. Is distributed to each horizontal transfer path, and when the correction control unit performs a correction operation, the distribution unit performs time series on the signal charges output from the same photoelectric conversion element. In particular, it is preferable to distribute to the horizontal transfer paths.

  In addition, it is preferable that a temperature detection unit that detects an ambient temperature is provided, and the correction control unit performs a correction operation when the temperature detected by the temperature detection unit is equal to or higher than a predetermined value.

  In addition, it is preferable that a motion detection unit that detects motion is provided, and the correction control unit stops the correction operation and does not perform correction when the amount of motion detected by the motion detection unit is equal to or greater than a predetermined amount. .

  It is preferable that the recording apparatus further includes a recording unit that records the digital data together with the linearity correction data.

  Furthermore, it is preferable that the image pickup means is a CMOS image sensor.

  The image pickup apparatus of the present invention moves the image pickup lens from the focus position to defocus (bokeh) when acquiring linearity correction data, so that the change in luminance within the light receiving surface of the incident light amount is reduced and the movement of the image pickup apparatus is reduced. The amount of change in pixel data associated with is reduced. For this reason, it is possible to perform the correction operation under external light without using a dedicated illumination device that irradiates a certain amount of light.

  In addition, the present invention changes the received light amount of the imaging means in a plurality of stages so as to include a light shielding state, determines an ideal straight line, and predetermined pixel data included in the digital data acquired for each stage of the received light amount And the linearity correction data in which the relationship between the pixel data and the difference amount is calculated and the digital data is corrected based on the linearity correction data. Degradation can be completely corrected and image quality degradation can be prevented.

  Further, according to the present invention, when the imaging unit includes a plurality of charge-voltage converters (output circuits), signal level matching between output systems can be achieved, and deviation between output systems of composite images can be prevented. it can.

  In FIG. 1 showing the configuration of the digital camera 10, the operation unit 11 includes a power switch 11a, a shutter button 11b, a mode switching dial 11c, and the like. The main control unit (CPU) 12 controls the operation of each unit via the bus line 13 based on the operation signal input from the operation unit 11. The EEPROM 14 stores a known gamma correction lookup table (LUT) 15a and a linearity correction LUT 15b. The shutter button 11b is composed of a two-stage switch. When the shutter button 11b is half-pressed, the first-stage switch (SW1) is turned on. When the shutter button 11b is fully-pressed, the second-stage switch (SW2) is turned on. The digital camera 10 performs a shooting preparation operation including photometry / ranging by turning on SW1, and performs a shooting operation by turning on SW2.

  On the subject side of the CCD image sensor (imaging means) 16, a mechanical shutter 17, a photographing lens 18, and a diaphragm 19 are provided, and motors 20, 21, and 22 are respectively connected. The motors 20 to 22 are independently controlled by a drive signal transmitted from the motor driver 23.

  The CCD image sensor 16 receives subject light that has passed through the mechanical shutter 17, the photographic lens 18, and the aperture 19, and performs photoelectric conversion (imaging) with a plurality of two-dimensionally arranged photoelectric conversion elements (photodiodes). A CCD driver 24 is connected to the CCD image sensor 16, and a timing generator (TG) 25 is connected to the CCD driver 24.

  The CCD image sensor 16 has an electronic shutter speed (signal charge accumulation time) controlled by a shutter speed control signal (for example, a vertical overflow drain control signal) supplied from the CCD driver 24, and the CCD driver 24. Based on the control signal for signal charge transfer (vertical transfer pulse and horizontal transfer pulse) supplied from the image signal, the charge-voltage converter (output circuit) picks up an imaging signal corresponding to the amount of signal charge (output circuit). Voltage signal) is serially output for each pixel. The mechanical shutter 17 and the electronic shutter of the CCD image sensor 16 function as a received light amount control unit. The light receiving portion of the CCD image sensor 16 is provided with an RGB color filter, and the color arrangement of the RGB color filter is a Bayer arrangement.

  An imaging signal output from the CCD image sensor 16 is an analog signal processing unit (digital data conversion means) including a correlated double sampling circuit (CDS) 26, an auto gain control amplifier (AGC) 27, and an A / D converter 28. ) 29 is digitized.

  The CDS 26 removes the amplifier noise and reset noise of the CCD image sensor 16. The AGC 27 is an amplifier that can change the gain in a programmable manner, and the CPU 12 sets a gain amount (that is, ISO sensitivity). The A / D converter 28 digitizes the imaging signal that has been subjected to noise removal and gain adjustment by the CDS 26 and the AGC 27 and generates RAW data (digital data). The RAW data output from the A / D converter 28 is temporarily stored in the image memory 30.

  The digital signal processing circuit 31 performs image processing such as signal interpolation, white balance adjustment, gamma correction, luminance / color difference conversion, and compression on the RAW data stored in the image memory 30 to generate image data. The LCD driver 32 displays the image data on a liquid crystal display (LCD) 33 sequentially (referred to as a through image display). The gamma correction is performed based on the gamma correction LUT 15a in the EEPROM 14. Gamma correction is a kind of gradation conversion and is a process for achieving consistency with a display system.

  Further, the integrating circuit 34 calculates an AE evaluation value and an AF evaluation value based on the RAW data stored in the image memory 30 and inputs them to the CPU 12. The CPU 12 adjusts the electronic shutter speed of the CCD image sensor 16 and the aperture value of the aperture 19 and performs exposure setting so that the AE evaluation value becomes an appropriate value. Further, the CPU 12 adjusts the lens position of the photographing lens 18 that condenses incident light on the CCD image sensor 16 and performs focus setting so that the AF evaluation value is maximized. This AE / AF operation is performed at regular intervals during live view display, and when the shutter button 11b is half-pressed, the exposure and focus settings made by the AE / AF operation are held.

  When the shutter button 11b is fully pressed, the media controller 35 performs imaging based on the AE / AF setting held when the shutter button 11b is half-pressed, and the RAW data recorded in the image memory 30 or the RAW data The image data after the digital signal processing is recorded on the memory card 36. The memory card 36 is detachable from the digital camera 10. The data format to be recorded on the memory card 36 can be selected by the operation unit 11.

  The linearity correction processing circuit 37 applies the level (QL value) of the pixel data constituting the RAW data based on the linearity correction LUT 15b in the EEPROM 14 with respect to the RAW data obtained by imaging with the full press of the shutter button 11b. Are converted so as to obtain linearity with respect to the amount of light incident on the CCD image sensor 16. As described above, the corrected RAW data is recorded as it is on the memory card 36 via the media controller 35, or after being subjected to digital signal processing by the digital signal processing circuit 31 and then via the media controller 35. To the memory card 36.

  The linearity correction LUT 15b is created by the CPU 12 immediately after the image pickup associated with the full press of the shutter button 11b. The CPU 12 controls the motor driver 23 to change the received light amount by controlling the mechanical shutter 17 and the electronic shutter of the CCD image sensor 16 in a state where the photographing lens 18 is shifted from the focus position by a predetermined amount (defocus state). A QL value is acquired from a predetermined pixel at each received light amount. The CPU 12 functions as correction data calculation means, obtains a QL value for a light reception amount outside the setting by linear interpolation, calculates a difference amount between each QL value and an ideal straight line, and a relationship between the difference amount and the QL value. Is created in the EEPROM 14 as a linearity correction LUT 15b.

  Next, a method for creating the linearity correction LUT 15b by the CPU 12 will be described with reference to FIG. The horizontal axis indicates the received light amount (charge accumulation amount) of the specific pixel of the CCD image sensor 16, and the vertical axis indicates the QL value corresponding to that pixel. A0 to A3 are the four different received light amounts S0 to S3. The actual data of the QL value is illustrated respectively. S0 is set by closing the mechanical shutter 17 and making it light-shielded. S1 to S3 are set by changing the electronic shutter speed (charge accumulation time) of the CCD image sensor 16 with the mechanical shutter 17 opened. Note that S3 corresponds to a saturated state in which the amount of light received by the CCD image sensor 16 is saturated (saturated accumulation state of signal charges).

The ideal straight line L is linear data connecting the coordinates (S3, B3) and the origin (S0, 0), and is defined as B3 = A3-A0. That is, B3 is a value obtained by subtracting the dark current component in the light shielding state from the QL value in the saturated state. The QL values B1 and B2 on the ideal straight line L in S1 and S2 are expressed as follows by proportional calculation.
B1 = (A3-A0). (S1-S0) / (S3-S0)
B2 = (A3-A0). (S2-S0) / (S3-S0)

  By subtracting B1 and B2 from A1 and A2, respectively, the amount of difference between the QL value and the ideal straight line L in each actual data can be obtained. The difference amount in other QL values is calculated by calculating the QL values between A0 to A1, between A1 and A2, and between A2 and A3 by linear interpolation, and the difference between each calculated QL value and the ideal straight line L is as above. It is obtained by calculating by a similar calculation. In this way, the linearity correction LUT 15b is created. Note that the light reception amount setting interval and the like may be changed as appropriate.

  Next, the operation of the digital camera 10 configured as described above will be described based on the flowchart of FIG. When the power is turned on by the power switch 11a and the photographing mode is set by the mode switching dial 11c, the photographing preparation operation is performed when the shutter button 11b is half-pressed. In this shooting preparation operation, an AE / AF operation is performed, and exposure setting and focus setting are performed. In this state, when the shutter button 11b is further fully pressed, actual shooting is performed, and an image pickup signal is output from the CCD image sensor 16. This imaging signal is an analog signal and is digitized via the analog signal processing unit 29 described above. This digitized imaging signal (RAW data) is temporarily stored in the image memory 30.

  Next, in order to perform the above-described linearity correction, first, the photographing lens 18 is moved from the focus position set in the AF operation during the above-described photographing preparation operation, and defocusing is performed. Due to this defocusing, the luminance change of the incident light in the light receiving surface of the CCD image sensor 16 becomes gradual. In this state, the mechanical shutter 17 and the electronic shutter of the CCD image sensor 16 are controlled, and the received light amount (charge accumulation amount) is changed step by step so as to include the light shielding state and the saturated state. An imaging operation (correction shooting) similar to the main shooting is performed. Then, based on the relationship between the QL value obtained from a specific pixel and the amount of received light, the linearity correction LUT 15b is created using the above-described method.

  Thereafter, the RAW data temporarily stored in the image memory 30 at the time of actual photographing is subjected to correction conversion (linearity correction) using the linearity correction LUT 15b, and each QL value and received light amount in the RAW data are subjected to correction conversion. Is linearized. When the digital camera 10 is set to the RAW recording mode, the RAW data subjected to linearity correction is recorded on the memory card 36. On the other hand, when the RAW recording mode is not set, the above-described digital signal processing is performed on the RAW data subjected to linearity correction, and the resulting image data is recorded on the memory card 36.

  As described above, in the present invention, since defocusing is performed at the time of correction photographing for creating the linearity correction LUT 15b, the luminance change of incident light in the light receiving surface of the CCD image sensor 16 becomes gradual. Even if movement occurs in the digital camera 10, the change in the amount of light incident on each pixel can be suppressed, so that the linearity correction LUT 15b is accurately created. Therefore, in the present invention, linearity correction can be performed under external light without using a dedicated illumination device for irradiating the CCD image sensor 16 with a fixed amount of light, and at the time of shooting performed by the user. In addition, linearity correction can be performed together.

  In the above embodiment, the CPU 12 is configured to execute the linearity correction after the main shooting. However, it is also preferable to configure the CPU 12 to execute the linearity correction before the main shooting. The operation of the digital camera 10 in this case will be described based on the flowchart of FIG. Similarly to the above, when the shutter button 11b is half-pressed, first, an AE / AF operation is performed as a shooting preparation operation, and exposure setting and focus setting are performed. Subsequently, the photographing lens 18 is moved from the focus position to perform defocusing, and in this state, the above-described correction photographing and linearity correction LUT 15b are created. When the creation of the linearity correction LUT 15b is completed, the photographing lens 18 is returned to the focus position set by the AF operation, and focus setting is performed. Here, the AF operation may be performed again.

  Next, when the shutter button 11b is fully pressed, the actual photographing is performed, and an image pickup signal is output from the CCD image sensor 16. This imaging signal is an analog signal and is digitized via the analog signal processing unit 29 described above. This digitized imaging signal (RAW data) is temporarily stored in the image memory 30. The RAW data is subjected to correction conversion (linearity correction) using the linearity correction LUT 15b, and the relationship between each QL value in the RAW data and the amount of received light is linearized. When the digital camera 10 is set to the RAW recording mode, the RAW data subjected to linearity correction is recorded on the memory card 36. On the other hand, when the RAW recording mode is not set, the above-described digital signal processing is performed on the RAW data subjected to linearity correction, and the resulting image data is recorded on the memory card 36.

  In the above embodiment, the RAW data after the linearity correction is recorded in the memory card 36 in the RAW recording mode. However, the linearity correction is not performed on the RAW data, and the RAW data is used for the linearity correction. RAW data may be recorded on the memory card 36 with the LUT 15b attached. The user can appropriately perform the linearity correction after fetching the RAW data in which the linearity correction LUT 15b is attached to the RAW data from the memory card 36 to a PC (personal computer) or the like.

  Further, as in the above-described embodiment, the acquisition of the linearity correction LUT 15b is performed at the time of shooting. However, the correction data acquisition mode for performing the acquisition of the linearity correction LUT 15b independently of the shooting. May be provided. The operation of the digital camera 10 in this case will be described based on the flowchart of FIG. The correction data acquisition mode can be manually set by the user using the mode switching dial 11c. When the correction data acquisition mode is set by the mode switching dial 11c, as described above, after the AE / AF operation is performed as the shooting preparation operation, the shooting for correction and the linearity correction are performed in a state where the defocus is performed. The LUT 15b is created. Details are as described above, and will be omitted.

  In this correction data acquisition mode, the linearity correction LUT 15b may be created individually for each drive mode of the digital camera 10. The drive mode is defined by a combination of ISO sensitivity, drive frequency of the CCD image sensor 16, aperture value, and the like. Accordingly, the linearity correction LUT 15b is not acquired at the time of shooting, and the linearity correction can be performed using the acquired linearity correction LUT 15b at the time of shooting.

  As a further extension, it is also preferable that the correction data acquisition mode is automatically executed based on a predetermined condition during standby until the shutter button 11b is operated in the shooting mode. Examples of the predetermined condition include ISO sensitivity set by the operation unit 11. As shown in FIG. 6, when the photographing mode is set by the mode switching dial 11c and the ISO sensitivity setting is a predetermined value (for example, ISO 800) or more, the above-described photographing preparation operation, defocusing, correction photographing, and linear The LUT 15b for sex correction is created in order.

  Further, it is also preferable that the correction data acquisition mode is automatically executed based on the temperature measured by the temperature sensor 38 provided as shown in FIG. 7 instead of the ISO sensitivity setting. As shown in FIG. 8, in the shooting mode, when the temperature measured by the temperature sensor 38 is equal to or higher than a predetermined value (for example, 30 ° C.), the above-described shooting preparation operation, defocusing, correction shooting, and linearity are performed. The correction LUT 15b is created in order. When the ISO sensitivity and temperature are high, a lot of noise is generated and the linearity is likely to deteriorate. Therefore, the correction processing can be efficiently performed by creating the linearity correction LUT 15b in advance.

  Furthermore, as shown in FIG. 9, it is also preferable to provide a motion detection unit 39 for detecting the motion of the digital camera itself. The motion detection unit 39 is configured by a gyro device or the like. When the digital camera is moved greatly by the user, the amount of light incident on the CCD image sensor 16 changes greatly, so that the effect of defocusing is not sufficiently exhibited. Therefore, the CPU 12 stops the above-described linearity correction operations (from defocusing to creation of the linearity correction LUT 15b) when the detected value of the amount of motion by the motion detection unit 39 is equal to or greater than a predetermined value. Do not execute.

  In the above-described embodiment, the CCD image sensor 16 that includes one charge-voltage converter (output circuit) and outputs the imaging signal serially is used as the imaging device. However, the imaging signal output speed is increased. For this reason, it is also preferable to apply the present invention when using an image pickup device that is provided with a plurality of charge voltage converters and outputs image pickup signals in parallel by the number of charge voltage converters. In this case, in addition to linearity with respect to the amount of light, signal level matching between output systems can be achieved.

  As shown in FIG. 10, the image sensor 40 is provided with a plurality of charge-voltage converters 41. A set of CDS 26, AGC 27, and A / D converter 28 is provided for each charge-voltage converter 41, and the above-described linearity correction processing is output from each charge-voltage converter 41 and digitized RAW Performed on data. Thereby, image quality deterioration due to a characteristic difference between a plurality of output systems is prevented, and the image quality of the composite image is improved.

  11 and 12 show specific examples of an image sensor having a plurality of charge-voltage converters. 11A, in the CCD image sensor 42, two charge-voltage converters 45a and 45b are connected to the output stage of a horizontal transfer path (HCCD) 44 arranged along the lower side of the light receiving unit 43. . The light receiving unit 43 is provided with a vertical transfer path (not shown).

  At the time of actual photographing, as shown in FIG. 11A, the signal charges read from the photoelectric conversion element (photodiode: PD) 43a arranged in the light receiving unit 43 and transferred to the HCCD 44 are output from the even columns. The signal charges are divided into the signal charges output from the odd-numbered columns, converted into imaging signals by the charge-voltage converters 45a and 45b, and output in parallel.

  On the other hand, at the time of shooting for correction, as shown in FIG. 11B, the signal charges read from the same PD 43a are distributed to the charge voltage converters 45a and 45b in time series by the HCCD 44, and each charge voltage is changed. The signals are alternately output as imaging signals from the converters 45a and 45b. At this time, the CPU 12 similarly performs defocusing. In the first charge transfer period, the signal charge read from the PD 43a is transferred to one charge-voltage converter 45a, and in the second charge transfer period, the signal charge read from the PD 43a is converted to the other charge-voltage converter. Is transferred to the device 45b. As described above, by making the signal charge supply sources (supply source pixels) to the charge-voltage converters 45a and 45b the same during correction shooting, the difference in the amount of received light due to the variation in the light-receiving characteristics of the PD 43a is eliminated. Therefore, the linearity correction LUT 15b can be created more accurately. Note that the number of charge-voltage converters connected to the HCCD 44 is not limited to two and may be three or more.

  12A, in the CCD image sensor 46, the light receiving unit 47 is divided into two regions 47a and 47b in the horizontal direction, and HCCDs 48a and 48b are provided corresponding to the regions 47a and 47b, respectively. , 48b are provided with charge-voltage converters 49a, 49b, respectively. A line memory (LM) 50 is provided between the light receiving unit 47 and the HCCDs 48a and 48b. As shown in FIG. 12, the LM 50 transfers the signal charges input from the regions 47a and 47b of the light receiving unit 47 to the corresponding HCCDs 47a and 47b, as shown in FIG. Can be transferred to the other HCCD by moving it horizontally in the LM50. The LM 50 functions as a distribution unit that distributes signal charges to the HCCDs 48a and 48b.

  At the time of actual photographing, as shown in FIG. 12A, the signal charges read from the PDs 51a and 51b arranged in the areas 47a and 47b are transferred to the corresponding HCCDs 48a and 48b via the LM 50, respectively. The image signals are output in parallel from the charge-voltage converters 49a and 49b of the HCCDs 48a and 48b.

  On the other hand, at the time of photographing for correction, as shown in FIG. 12B, the signal charges read from the PDs 51a and 51b in the respective regions 47a and 47b are distributed to the left and right HCCDs 48a and 48b by the LM 50 in time series. Output from the charge voltage converters 49a and 49b of the HCCDs 48a and 48b as imaging signals. At this time, the CPU 12 similarly performs defocusing. In the first charge transfer period, for example, the signal charge read from the PD 51a is transferred to one HCCD 48a by the LM 50, and in the subsequent second charge transfer period, the signal charge read from the same PD 51b is After being moved in the horizontal direction by the LM 50, it is transferred to the other HCCD 48b. At this time, each signal charge is horizontally transferred from the base end side of each HCCD 48a, 48b to each charge voltage converter 49a, 49b on the other end side, and the horizontal transfer path is symmetrical. In this case as well, since the signal charge supply sources (source pixels) to the charge-voltage converters 49a and 49b are the same at the time of shooting for correction, the linearity correction LUT 15b is created more accurately. can do. The area division of the light receiving unit 47 is not limited to two divisions and may be three or more divisions.

  11 and 12, the HCCD is disposed along the lower side of the light receiving unit. However, the present invention is not limited to this, and the light receiving unit is divided into upper and lower parts, and signal charges are simultaneously received from the respective regions. HCCDs may be arranged above and below the light receiving section so that they can be read out.

  In the above-described embodiment, the QL value in the light shielding state is acquired by performing imaging while the mechanical shutter 17 is closed at the time of correction shooting. However, the present invention is not limited to this, and FIG. As shown in the CCD image sensor 52, an optical black (optical black: OB) region 54 in which the PD 53a is shielded by a metal layer or the like is provided in the periphery of the light receiving portion 53 where the PD 53a is disposed. A QL value in a light-shielded state may be acquired from an imaging signal output via the charge-voltage converter 56. Further, the QL value in the light shielding state is not necessarily acquired every time correction shooting is performed, and the QL value acquired at the previous correction shooting may be used. Although FIG. 13 shows the case where there is one charge-voltage converter, the same applies to the case where there are a plurality of charge-voltage converters as shown in FIGS.

  In the above-described embodiment, a CCD image sensor is exemplified as the image pickup device. However, the present invention is not limited to this, and other image sensors such as a CMOS image sensor can be applied. FIG. 14 shows a configuration of a digital camera using a CMOS image sensor instead of the CCD image sensor. In the figure, a CMOS image sensor 60 includes a sensor unit including a photoelectric conversion unit (light receiving unit) 61, a vertical shift register 62, a vertical amplifier 63, and a horizontal shift register 64, and a timing generator formed on the same substrate. (TG) 65, an A / D converter 66, a line memory 67, and a peripheral circuit unit including a digital interface (I / F) 68. The CMOS image sensor 60 performs an imaging operation under the control of the CPU 12, and an imaging signal (RAW data) output from the CMOS image sensor 60 is taken into the image memory 30. The other parts are the same as those in the above embodiment, and are therefore given the same reference numerals, and will not be described in detail.

It is a block diagram which shows the digital camera to which this invention is applied. It is a graph which shows the measurement data and ideal curve of QL value with respect to the amount of received light. It is a flowchart explaining operation | movement of a digital camera. 10 is a flowchart illustrating an example in which correction shooting and creation of a linearity correction LUT are performed after a shooting preparation operation. It is a flowchart explaining operation | movement of correction data acquisition mode. It is a flowchart explaining the example which operated the correction data acquisition mode according to the setting value of ISO sensitivity. It is a block diagram which shows the digital camera provided with the temperature sensor. It is a flowchart explaining the example which operated the correction data acquisition mode according to the temperature which a temperature sensor measures. It is a block diagram which shows the digital camera provided with the motion detection part. It is a block diagram which shows the analog signal processing part connected to the CCD image sensor which has a some charge voltage converter. It is a figure which shows the CCD image sensor in which the several charge voltage converter was connected to HCCD. It is a figure which shows the CCD image sensor provided with the some HCCD. It is a figure which shows the CCD image sensor provided with the optical black area | region. It is a block diagram which shows the digital camera incorporating a CMOS image sensor.

Explanation of symbols

10 Digital camera (imaging device)
12 Main control unit (correction data calculation means, correction control means)
15a Look-up table for gamma correction 15b Look-up table for linearity correction (data for linearity correction)
16 CCD image sensor (imaging means)
17 Mechanical shutter 18 Shooting lens 19 Aperture 26 Correlated double sampling circuit 27 Auto gain control amplifier 28 A / D converter 29 Analog signal processing unit (digital data conversion means)
Reference Signs List 30 Image memory 31 Digital signal processing circuit 34 Integration circuit 36 Memory card 37 Linearity correction processing circuit (correction processing means)
38 Temperature sensor (temperature detection means)
39 Motion detector (motion detector)
DESCRIPTION OF SYMBOLS 40 Image pick-up element 41 Charge voltage converter 42 CCD image sensor 43 Light receiving part 44 Horizontal transfer path 45a, 45b Charge voltage converter 46 CCD Image sensor 47 Light receiving part 48a, 48b Horizontal transfer path 49a, 49b Charge voltage converter 50 Line memory ( Sorting means)
52 CCD image sensor 53 Light receiving portion 54 Optical black area 55 Horizontal transfer path 56 Charge voltage converter 60 CMOS image sensor

Claims (9)

Imaging means for converting signal charges generated by a plurality of two-dimensionally arranged photoelectric conversion elements into imaging signals by a charge-voltage converter and outputting the imaging signals;
An imaging lens for condensing incident light on the imaging means;
Digital data conversion means for performing predetermined processing on the imaging signal output from the imaging means and converting it to digital data;
A received light amount control means for changing the received light amount of the imaging means in a plurality of stages so as to include a light shielding state;
Difference amount between predetermined pixel data included in the digital data generated in each received light amount set by the received light amount control means and an ideal straight line obtained from the pixel data in the light shielding state and a predetermined exposure state Correction data calculation means for calculating linearity correction data relating the difference amount and the pixel data;
Correction processing means for correcting the digital data based on the linearity correction data;
A correction control unit that drives the imaging lens, moves the imaging lens from a focus position to perform defocusing, and operates the received light amount control unit, the correction data calculation unit, and the correction processing unit;
An imaging apparatus comprising:   The imaging apparatus according to claim 1, wherein the correction data calculation unit calculates the pixel data for a received light amount not set by the received light amount control unit by linear interpolation.   The imaging means includes a plurality of the charge voltage converters for outputting imaging signals in parallel, and the correction data calculation means calculates the linearity correction data for each of the charge voltage converters, The correction processing means corrects the digital data corresponding to each of the charge-voltage converters using the linearity correction data calculated for each of the charge-voltage converters. The imaging device described.   The imaging means includes a horizontal transfer path for horizontally transferring the signal charge read from the photoelectric conversion element and vertically transferred to the charge voltage converter, and the charge voltage converter is provided in the horizontal transfer path. When the correction control means performs a correction operation, the horizontal transfer path is configured so that the signal charges read from the same photoelectric conversion element are time-sequentially connected to each of the charge-voltage converters. The image pickup apparatus according to claim 3, wherein the image pickup apparatus is assigned to the image pickup apparatus.   The imaging means includes a plurality of horizontal transfer paths that horizontally transfer signal charges read from the photoelectric conversion elements and vertically transferred toward the charge voltage converter, and signal charges read from the photoelectric conversion elements. And a distribution unit that distributes each horizontal transfer path. When the correction control unit executes a correction operation, the distribution unit performs time-series processing on the signal charges output from the same photoelectric conversion element. The imaging apparatus according to claim 4, wherein the imaging apparatus is assigned to each horizontal transfer path.   The temperature detecting means for detecting an ambient temperature is provided, and the correction control means performs a correcting operation when the temperature detected by the temperature detecting means is equal to or higher than a predetermined value. 5. The imaging device according to any one of 5.   It comprises a motion detection means for detecting motion, and the correction control means stops the correction operation and does not perform correction when the amount of motion detected by the motion detection means is a predetermined amount or more. The imaging apparatus according to claim 1, wherein   8. The imaging apparatus according to claim 1, further comprising recording means for recording the digital data together with the linearity correction data.   9. The imaging apparatus according to claim 1, wherein the imaging means is a CMOS image sensor.

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