JP2007158830A - Image pickup device and image pickup device control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inexpensively apply a countermeasure for preventing an OB part from being affected by a light leak to the OB part caused by a large incident light amount due to a high-luminance subject or the like. <P>SOLUTION: It is detected that an output level in an OB pixel part is changed corresponding to a distance from an effective pixel part. An OB region for calculating a dark level is changed corresponding to the detection results. Consequently, it is possible to detect a proper dark level that is not affected by the light leak to the OB pixel part caused by the large incident light amount due to the high-luminance subject or the like. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an imaging apparatus and a method for controlling the imaging apparatus, and more particularly to a technique suitable for use in performing OB clamping.

  2. Description of the Related Art Conventionally, an image processing apparatus such as an electronic camera that records and reproduces a still image or a moving image captured by a solid-state imaging device such as a CCD or CMOS using a memory card having a solid-state memory element as a recording medium is already on the market.

  Many of the image pickup devices of these electronic cameras have a plurality of pixels shielded by an aluminum film or the like called OB (Optical Black) pixels, and have an output value of the OB pixel range (hereinafter referred to as an OB portion). There are many imaging devices that perform OB clamping as a dark level. Here, the dark level adjustment by the OB clamp has the following problems.

  That is, there is a possibility that a phenomenon may occur in which the whole or part of the OB portion has a level different from the dark level of the effective pixel portion. As a specific example, for example, a case where a high-luminance subject exists near the OB portion and the amount of incident light is large will be described. In such a case, a phenomenon occurs in which the level of the OB portion cannot maintain the dark level of the effective pixel portion due to light leakage or blooming from the adjacent effective pixel region, although the light is blocked.

  If a deviation occurs between the output level of the OB portion and the dark level of the effective pixel portion, the value of the dark state without incident light is wrong, and the linearity of the output signal with respect to the incident light amount cannot be maintained. As a result, there arises a problem that, for example, the color after white balance processing becomes strange.

  FIG. 8 is a diagram illustrating a problem example in which OB floating that occurs when incident light from a high-luminance subject is present near the boundary between the OB portion and the effective pixel portion. FIG. 8A shows before horizontal OB clamping, and FIG. 8B shows after horizontal OB clamping. Here, the horizontal OB clamp means that the dark level of each row in the obtained image is clamped to the level of the horizontal OB portion of that row.

  In this problem example, the level of the OB part is partially raised by the high-intensity incident part shown in FIG. 8A. When horizontal OB clamping is performed using this OB part, as shown in FIG. The dark level of the row where the OB is raised is lowered, and the sunken portion is generated in a band shape.

  Various proposals have been made as countermeasures against such light leakage to the OB region. For example, in the imaging device proposed in Patent Document 1, occurrence of light leakage to the OB portion due to high-intensity incident light is Detection is performed by calculating the output level of the OB section. Then, based on the output result of the OB portion, when the level of the OB portion is high, measures are taken such as using an OB region that is not easily affected by light leakage and is far from the effective pixel region.

Japanese Patent Laid-Open No. 9-247552

  However, in the method of dealing with the problem of light leakage to the OB region in such a conventional solid-state imaging device such as an electronic camera, there are the following problems. That is, the phenomenon in which the output level of the OB portion differs from the dark level of the effective pixel portion is not only light leakage. For example, as shown in FIG. 9A, a phenomenon called “OB step” may occur in which the dark current amount is different between the OB portion and the effective pixel portion. FIG. 9B shows the luminance distribution. Further, as shown in FIG. 10A, the dark current amount becomes uneven locally, and for example, there is a phenomenon that the dark current amount increases toward the periphery of the pixel region due to heat generation of the peripheral circuit. Similarly, FIG. 10B shows the luminance distribution. If measures similar to those in the case of “light leakage” such as “use OB region far from effective pixel region” are applied to these phenomena, there is no effect on the phenomenon of FIG. However, the phenomenon of FIG. 10 has an adverse effect.

  In addition, when taking measures to use an OB area far from the effective pixel area, if an OB area that is not reliably affected by high-intensity incidence is to be secured, the OB area must be greatly enlarged. There is a problem that it is necessary to increase the chip size, which increases the manufacturing cost of the image sensor.

  SUMMARY OF THE INVENTION In view of the above-described problems, an object of the present invention is to provide a low-cost measure for preventing the influence of light leakage on an OB portion due to a large amount of incident light by a high-luminance subject or the like. Yes.

  An imaging apparatus according to the present invention is an imaging apparatus that records image data generated by imaging a subject on a recording medium, and includes a plurality of pixels that convert an optical signal exposed by reflected light from the subject into an electrical signal. An image pickup device comprising an effective pixel portion having an OB pixel portion formed adjacent to the effective pixel portion and shielded from light in front of the effective pixel portion, and darkness of the image data based on an output level in the OB pixel portion. An OB clamp unit that determines a level; and an OB pixel unit change detection unit that detects that an output level in the OB pixel unit changes according to a distance from the effective pixel unit. Is characterized in that the OB area for calculating the dark level is changed according to the detection result by the OB pixel part change detecting means.

  An imaging apparatus control method according to the present invention is an imaging apparatus control method for recording image data generated by imaging a subject on a recording medium, wherein an optical signal exposed by reflected light from the subject is converted into an electrical signal. In an imaging device comprising an effective pixel portion having a plurality of pixels to be converted and an OB pixel portion formed adjacent to the effective pixel portion and shielded from light in front of the effective pixel portion, based on the output level in the OB pixel portion An OB clamping step for determining the dark level of the image data, and an OB pixel portion change detection step for detecting that the output level in the OB pixel portion changes according to the distance from the effective pixel portion. In the OB clamping step, the OB region for calculating the dark level is changed according to the detection result of the OB pixel portion change detection step.

  According to the present invention, it is detected that the output level in the OB portion changes according to the distance from the effective pixel portion, and the OB region for calculating the dark level is changed according to the detection result. In addition, an appropriate dark level that is not affected by light leakage to the OB portion due to a large amount of incident light by a high-luminance subject or the like can be detected at low cost. Thereby, it is possible to prevent an OB clamp error from occurring.

(First embodiment)
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram illustrating a configuration example of an electronic camera according to the present embodiment.
In FIG. 1, reference numeral 100 denotes an image processing apparatus. Reference numeral 12 denotes a shutter having a diaphragm function for controlling the exposure amount of the image sensor 14. An image sensor 14 converts an optical image into an electric signal. A light beam incident on the lens unit 300 including a plurality of lenses, a diaphragm, a shutter, and the like is determined as an optical image on the image sensor 14.

  The light beam incident on the photographing lens 310 in the lens unit 300 is an optical image on the image sensor 14 guided by the single-lens reflex system through the diaphragm 312, the outer lens mount 306, the inner lens mount 106, the first mirror 130 and the shutter 12. To form an image.

  Reference numeral 15 denotes an analog signal processing circuit (AFE) that performs various processes on the analog signal output from the image sensor 14. The analog signal processing circuit 15 includes a CDS unit 16 that performs correlated double sampling of an input analog image signal, a PGA unit 17 that applies a predetermined gain to the analog image signal, and an A / D conversion that converts the analog signal into a digital signal. Part 18. In this embodiment, horizontal OB clamping described later is performed by the analog signal processing circuit 15.

  A timing generation circuit 19 supplies a clock signal and a control signal to the image sensor 14 and the analog signal processing circuit 15 and is controlled by the memory control circuit 22 and the system control circuit 50.

  An image processing circuit 20 performs predetermined pixel interpolation processing and color conversion processing on data from the analog signal processing circuit 15 or data from the memory control circuit 22. Further, the image processing circuit 20 performs predetermined arithmetic processing using image data captured as necessary, and based on the obtained arithmetic result, a TTL (through the lens) type AWB (auto white balance). Process. Note that the OB integration described later in the present embodiment is performed by the image processing circuit 20.

  A memory control circuit 22 controls the analog signal processing circuit 15, the timing generation circuit 19, the image processing circuit 20, the memory 30, and the compression / decompression circuit 32. Data sent from the analog signal processing circuit 15 is written into the image display memory 24 or the memory 30 via the image processing circuit 20 and the memory control circuit 22 or directly via the memory control circuit 22.

  Reference numeral 24 denotes an image display memory, and reference numeral 26 denotes a D / A converter. Reference numeral 28 denotes an image display unit composed of a TFT LCD. The display image data written in the image display memory 24 is displayed on the image display unit 28 via the D / A converter 26. When the captured image data is sequentially displayed on the image display unit 28, an electronic viewfinder function can be realized.

  Reference numeral 30 denotes a memory for storing captured still images and moving images. The memory 30 can also be used as a work area for the system control circuit 50. Reference numeral 32 denotes a compression / decompression circuit that compresses and decompresses image data by adaptive discrete cosine transform (ADCT) or the like, reads an image stored in the memory 30, performs compression processing or decompression processing, and stores the processed data in the memory Write to 30.

  Reference numeral 40 denotes a shutter control unit that controls the shutter 12 in cooperation with an aperture control unit 340 that controls the aperture 312 based on control by the system control circuit 50. A system control circuit 50 controls the entire image processing apparatus 100 and controls a series of imaging operations including control of the shutter 12 via the shutter control circuit 40 and aperture control via the aperture controller 340. The system control circuit 50 is a circuit that controls various operations by an AE (automatic exposure) and AF (autofocus) circuit (not shown) according to various settings.

  Reference numerals 90 and 94 denote first and second interfaces with a recording medium such as a memory card and a hard disk. Reference numerals 92 and 96 denote first and second inner sides for connection with a recording medium such as a memory card and a hard disk. It is a connector.

  Reference numeral 98 denotes a recording medium attachment / detachment detection unit that detects whether or not the first and second recording media 200 and 210 are attached to the first inner connector 92 and the second inner connector 96. Reference numeral 120 denotes a fifth interface for connecting the image processing apparatus 100 to the lens unit 300 in the inner lens mount 106.

  Reference numerals 130 and 132 denote first and second mirrors, respectively, which guide light rays incident on the photographing lens 310 to the optical viewfinder 104 by a single-lens reflex system. The second mirror 132 may be either a quick return mirror or a half mirror.

  Reference numeral 200 denotes a first recording medium such as a memory card or a hard disk. The first recording medium 200 is connected to the first recording unit 202 configured by a semiconductor memory, a magnetic disk, or the like, the third interface 204 for connecting to the image processing apparatus 100, and the image processing apparatus 100. And a first outer connector 206.

  210 is the same as the first recording medium 200, and is a second recording medium such as a memory card or a hard disk. The second recording medium 210 is connected to a second recording unit 212 configured by a semiconductor memory, a magnetic disk, or the like, a fourth interface 214 for connecting to the image processing apparatus 100, and the image processing apparatus 100. And a second outer connector 216.

  Reference numeral 300 denotes an interchangeable lens type lens unit. Reference numeral 306 denotes an outer lens mount that mechanically couples the lens unit 300 to the image processing apparatus 100. Various functions for electrically connecting the lens unit 300 to the image processing apparatus 100 are included in the outer lens mount 306.

  Reference numeral 310 denotes a photographing lens, and 312 denotes an aperture. Reference numeral 320 denotes a sixth interface for connecting the lens unit 300 to the image processing apparatus 100 in the outer lens mount 306.

  Reference numeral 322 denotes a third outer connector that electrically connects the lens unit 300 to the image processing apparatus 100, and is connected to the third inner connector 122 of the image processing apparatus 100. The third outer connector 322 has a function of transmitting control signals, status signals, data signals, and the like between the image processing apparatus 100 and the lens unit 300 and supplying various currents or supplying currents. .

  Reference numeral 340 denotes an aperture control unit that controls the aperture 312 in cooperation with the shutter control unit 40 that controls the shutter 12 based on control by the system control circuit 50. Reference numeral 342 denotes a distance measurement control unit that controls focusing of the photographing lens 310. Reference numeral 344 denotes a zoom control unit that controls zooming of the photographing lens 310, and reference numeral 350 denotes a lens system control circuit that controls the entire lens unit 300.

Next, the operation of the present embodiment will be described with reference to FIGS.
FIG. 2 is a flowchart illustrating an imaging sequence in an imaging apparatus configured to perform clamping to a dark level using a horizontal OB clamp as a first example in the present embodiment.

  With the start of imaging, the system control circuit 50 starts signal accumulation in the image sensor 14 via the timing generation circuit 19 (step S101). Next, after exposure is performed by opening and closing the shutter 12 (step S102), signal accumulation in the image sensor 14 is terminated (step S103).

  Next, reading is started from the first row in the horizontal OB portion (step S104). Then, the analog signal processing circuit 15 detects light leakage when outputting the horizontal OB portion at the time of reading the horizontal OB portion in the row reading (step S105). Next, the dark level used for the dark clamp in the horizontal OB clamp is set based on the detection result (step S106).

  The analog signal processing circuit 15 performs row reading of the effective pixel portion while performing clamping so that the dark level obtained in step S106 becomes a predetermined value (step S107). When the row reading of the effective pixel portion is completed, it is determined whether or not the row is the last row (step S108). If the result of this determination is the last row, the series of shooting operations are terminated. On the other hand, if the result of determination in step S108 is not the last line, the process returns to step S104 to read the next line.

FIG. 3 is a flowchart illustrating an imaging sequence in an imaging apparatus having a configuration in which the average output value of the horizontal OB unit is set to a dark level and dark clamping is performed by horizontal OB integration as a second example in the present embodiment.
With the start of shooting, the system control circuit 50 starts signal accumulation in the image sensor 14 via the timing generation circuit 19 (step S201). Next, after exposure is performed by opening and closing the shutter 12 (step S202), signal accumulation in the image sensor 14 is terminated (step S203).

  Next, the signal accumulated via the analog signal processing circuit 15 is read (step S204) and temporarily stored in the memory 30. Then, the image processing circuit 20 detects light leakage to the horizontal OB portion in each row for the acquired image stored in the memory 30 (step S205), and determines whether or not light leakage has occurred as a result. (Step S206).

  If no light leakage occurs as a result of this determination, the first OB integration region close to the effective pixel region is selected as the OB integration region (step S207). On the other hand, if light leakage has occurred as a result of the determination in step S206, the second OB integration region that is farther from the effective pixel region than the first OB integration region is set as the OB integration region (step S208). .

  Next, the dark level is obtained from the calculation result of the output level of the set OB integration region (step S209). Finally, the image processing circuit 20 offsets the level of the entire screen so that the dark level becomes a predetermined value (step S210), and the series of photographing operations is completed.

FIG. 4 is a flowchart of a sequence for detecting the presence or absence of light leakage to the horizontal OB unit in step S105 of FIG. 2 and step S205 of FIG.
First, in each row, the average output value of each of the divided areas is calculated (step S301), and it is determined whether or not the variation in the average output value of the plurality of areas is within a predetermined range (step S302). As a result of the determination, if the variation in the average output value is within the predetermined range, it is determined that no light leaks to the OB portion in that row (step S305).

  On the other hand, as a result of the determination in step S302, if the variation in the average output value of the plurality of regions exceeds the predetermined range, the average output value of each region continues to increase as the region is closer to the effective pixel region. It is determined whether or not (step S303). As a result of this determination, if the average output value is larger in the region closer to the effective pixel region, it is determined that light leakage to the OB portion has occurred in that row (step S304).

  On the other hand, as a result of the determination in step S303, if the average output value is not larger in the region closer to the effective pixel region, it is determined that light leakage to the OB portion in that row has not occurred (step S305). Then, when it is determined in step S304 or step S305 whether or not there is light leakage to the OB part, the light leakage detection routine to the horizontal OB part is ended.

FIG. 5 is a flowchart showing an example of the procedure for setting the OB clamp level in step S106 of FIG.
With the start of the OB clamp level setting routine, first, the presence or absence of light leakage is determined (step S401). If no light leakage occurs as a result of this determination, the first OB clamp area close to the effective pixel area is selected as the horizontal OB clamp area (step S402). On the other hand, if light leakage has occurred as a result of the determination in step S401, a second OB clamp region that is farther from the effective pixel region than the first OB clamp region is selected (step S403). And the output value of the OB clamp area | region set by step S402 and step S403 is calculated (step S404). Next, the OB clamp level of that row is set (step S405), and the OB clamp level setting routine is terminated.

FIG. 6 is a flowchart for explaining an example of an OB clamp level setting procedure different from the flowchart of FIG. 5 in step S106 of FIG.
With the start of the OB clamp level setting routine, first, the presence or absence of light leakage is determined (step S501).

  If no light leakage occurs as a result of this determination, an output value in a region predetermined as a horizontal OB clamp region is calculated (step S502). Next, the value is set to the OB clamp level of the row (step S503), and the OB clamp level setting routine is terminated. On the other hand, if light leakage has occurred as a result of the determination in step S501, the OB clamp level setting routine is terminated without updating the OB clamp level.

FIG. 7 is a diagram for explaining in detail an example of a method of detecting the inclination (change) of the OB portion in the present embodiment.
The graph shown in FIG. 7 represents the output level of a certain row. The horizontal axis is an address in the horizontal direction, and particularly, the horizontal OB portion is mainly described. The vertical axis is the output level. In FIG. 7, since there is a large amount of incident light in the effective pixel region close to the horizontal OB portion, light leakage occurs in the horizontal OB portion, and the output level in the horizontal OB increases as the region near the effective pixel increases. It represents the state of having.

  In the inclination detection method described with reference to FIG. 7, the horizontal OB portion is divided into five blocks (1) to (5), and an average output value in each block is calculated. Then, it is determined whether or not the average output value of each block is within a predetermined range. As a result of this determination, if there is a block that does not fall within the predetermined range, and the value is larger as the value of each block is closer to the effective pixel area, “OB floating due to light leakage” has occurred. judge.

  In the flowcharts of FIGS. 2 to 6, blocks (2) and (3) except for a block (1) that is easily affected by heat generation of peripheral circuits and a block (5) that is easily affected by light leakage. The average value of the output values in the areas (4) and (4) is set as the dark level. Then, horizontal OB clamping or horizontal OB integration is performed. If it is determined that “OB floating due to light leakage” has occurred as a result of the inclination detection of the horizontal OB portion, the dark level is set according to the determination result. Change the defined area.

  More specifically, in the first example described with reference to FIGS. 2 and 5, the areas of the blocks (1) to (3) calculated to be within the predetermined range at the time of detecting the horizontal OB portion inclination are shown. Use the average output value as the dark level. In the second example described with reference to FIG. 3, for example, horizontal OB clamping or horizontal OB integration is performed with the average output value of the areas of blocks (1) and (2) far from the effective pixel area as the dark level.

  In another form of the first example described in FIG. 2 and FIG. 6, a dark level is determined from the horizontal OB portion of a row for which it is determined that “OB floating due to light leakage” has occurred. Don't ask for. Instead, using the dark level of the row immediately before the occurrence of OB floating, the dark level of that row is determined and horizontal OB clamping is performed. Further, in the case of horizontal OB integration, calculation is performed excluding the row where “OB floating due to light leakage” occurs.

  In the present embodiment, the horizontal OB portion is divided into five. However, by dividing the horizontal OB portion into a larger number of blocks, it is possible to detect an inclination with higher resolution. Further, by expanding the area of each block with a smaller number of divisions, it is possible to reduce the possibility of erroneous determination due to the influence of random noise, scratches, and the like.

The embodiment has been described above with reference to FIGS.
In this embodiment, in order to clamp the output of the horizontal OB, the inclination of the horizontal OB portion is detected and light leakage to the horizontal OB portion is obtained. However, in order to clamp the output of the vertical OB, The light leakage to the vertical OB portion may be obtained by detecting the inclination of the OB portion. Of course, there is no problem even if both horizontal and vertical OBs are monitored.

  In the description of the present embodiment, when the OB clamp level is calculated and set, the setting of the OB integration area described with reference to FIG. 3 and the horizontal OB clamp area described with reference to FIGS. In the above setting, one of the two areas corresponding to when light leakage occurs and when no light leakage occurs is selected. However, three or more areas are calculated as OB clamp level calculation areas. There is no problem even if the configuration is selected from the area. For example, based on the output values of a plurality of divided areas used when detecting the output gradient in the OB area in FIG. 4, all or a part of the divided areas that are not abnormally output are converted into the OB clamp level calculation area. There is no problem even if the average output value of the region is set to the OB clamp level.

  Note that the first and second recording media 200 and 210 are not only a memory card such as a PCMCIA card or a compact flash (registered trademark), a hard disk, or the like. Of course, there is no problem even if it is composed of a micro DAT, a magneto-optical disk, an optical disk such as a CD-R or CD-RW, a phase change optical disk such as a DVD.

  Of course, there is no problem even if the first and second recording media 200 and 210 are composite media in which a memory card and a hard disk are integrated. Further, there is no problem even if a part of the composite medium is detachable.

  In the description of the present embodiment, the first and second recording media 200 and 210 have been described as being separated from the image processing apparatus 100 and arbitrarily connectable. However, any or all of the recording media may be used. Of course, there is no problem even if the image processing apparatus 100 remains fixed.

  The first recording medium 200 or the second recording medium 210 may be configured to be connectable to the image processing apparatus 100 by a single number or a plurality. The first and second recording media 200 and 210 have been described as being mounted on the image processing apparatus 100, but there is of course no problem if the recording medium has a single or a plurality of combinations.

(Other embodiments according to the present invention)
Each means constituting the image pickup apparatus and each step of the control method of the image pickup apparatus in the embodiment of the present invention described above can be realized by operating a program stored in a RAM or ROM of a computer. This program and a computer-readable recording medium recording the program are included in the present invention.

  Further, the present invention can be implemented as, for example, a system, apparatus, method, program, or recording medium. Specifically, the present invention may be applied to a system including a plurality of devices. The present invention may be applied to an apparatus composed of a single device.

  In the present invention, a software program (in the embodiment, a program corresponding to the flowcharts shown in FIGS. 2 to 6) for realizing the functions of the above-described embodiments is directly or remotely supplied to the system or apparatus. This includes the case where the system or the computer of the apparatus is also achieved by reading and executing the supplied program code.

  Accordingly, since the functions of the present invention are implemented by computer, the program code installed in the computer also implements the present invention. In other words, the present invention includes a computer program itself for realizing the functional processing of the present invention.

  In that case, as long as it has the function of a program, it may be in the form of object code, a program executed by an interpreter, script data supplied to the OS, and the like.

  Examples of the recording medium for supplying the program include a floppy (registered trademark) disk, a hard disk, an optical disk, and a magneto-optical disk. Further, there are MO, CD-ROM, CD-R, CD-RW, magnetic tape, nonvolatile memory card, ROM, DVD (DVD-ROM, DVD-R) and the like.

  As another program supply method, there is a method of connecting to a homepage on the Internet using a browser of a client computer. The computer program itself of the present invention or a compressed file including an automatic installation function can be downloaded from the homepage by downloading it to a recording medium such as a hard disk.

  It can also be realized by dividing the program code constituting the program of the present invention into a plurality of files and downloading each file from a different homepage. That is, a WWW server that allows a plurality of users to download a program file for realizing the functional processing of the present invention on a computer is also included in the present invention.

  As another method, the program of the present invention is encrypted, stored in a recording medium such as a CD-ROM, distributed to users, and encrypted from a homepage via the Internet to users who have cleared predetermined conditions. Download the key information to be solved. It is also possible to execute the encrypted program by using the key information and install the program on a computer.

  Further, the functions of the above-described embodiments are realized by the computer executing the read program. Furthermore, based on the instructions of the program, an OS or the like running on the computer performs part or all of the actual processing, and the functions of the above-described embodiments can be realized by the processing.

  As another method, the program read from the recording medium is first written in a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer. Then, based on the instructions of the program, the CPU or the like provided in the function expansion board or function expansion unit performs part or all of the actual processing, and the functions of the above-described embodiments are also realized by the processing.

It is a block diagram which shows an example of the function structure in the 1st Embodiment of this invention. 5 is a flowchart illustrating a first example of a main routine in the first embodiment of the present invention. 7 is a flowchart illustrating a second example of a main routine in the first embodiment of the present invention. It is a flowchart which shows an example of the process sequence which detects the light leak in the 1st Embodiment of this invention. It is a flowchart which shows the 1st example of the process sequence which sets the OB clamp level in the 1st Embodiment of this invention. It is a flowchart which shows the 2nd example of the process sequence which sets the OB clamp level in the 1st Embodiment of this invention. It is a figure which shows an example of the inclination detection method of the OB part in the 1st Embodiment of this invention. It is a figure explaining the example of a conventional problem. It is a figure explaining the example of a problem which cannot be solved by a prior art example. It is a figure explaining the other example of a problem which cannot be solved by a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 12 Shutter 14 Image pick-up element 15 Analog signal processing circuit 16 CDS part 17 PGA part 18 A / D conversion part 19 Timing generation circuit 20 Image processing circuit 22 Memory control circuit 24 Image display memory 26 D / A converter 28 Image display part 30 Memory 32 Compression / decompression circuit 40 Shutter control unit 50 System control circuit 90 First interface 92 First inner connector 94 Second interface 96 Second inner connector 98 Recording medium attachment / detachment detection unit 100 Image processing device 104 Optical viewfinder 106 Inside Lens mount 120 Fifth interface 122 Third inner connector 130 First mirror 132 Second mirror 200 First recording medium 202 First recording unit 204 Third interface 206 First outer connector 210 Second Record Medium 212 Second recording unit 214 Fourth interface 216 Second outer connector 300 Lens unit 306 Outer lens mount 310 Shooting lens 312 Aperture 320 Sixth interface 322 Third outer connector 340 Aperture control unit 342 Distance control unit 344 Zoom control unit 350 Lens system control circuit

Claims (22)

An imaging apparatus that records image data generated by imaging a subject on a recording medium,
An effective pixel portion having a plurality of pixels that convert an optical signal exposed by reflected light from the subject into an electrical signal, and an OB pixel portion that is formed adjacent to the effective pixel portion and whose front surface is shielded from light An image pickup device,
OB clamping means for determining a dark level of the image data based on an output level in the OB pixel unit;
OB pixel part change detecting means for detecting that the output level in the OB pixel part changes according to the distance from the effective pixel part,
The imaging apparatus according to claim 1, wherein the OB clamping unit changes an OB region for calculating the dark level in accordance with a detection result by the OB pixel unit change detection unit. The OB pixel part change detecting means has a flat part extracting means for extracting a range where there is no change in the output level in the OB pixel part,
The imaging apparatus according to claim 1, wherein the OB clamp unit determines a clamp level based on an output level of an OB range extracted by the flat part extraction unit.   The OB pixel unit change detecting unit determines that light leakage to the OB pixel unit is occurring when the output level increases as the effective pixel unit approaches the OB pixel unit. The imaging apparatus according to claim 1, further comprising:   The OB clamp means determines the clamp level based on the output level of the OB range away from the effective pixel portion when the light leakage determination means determines that the light leakage has occurred. The imaging apparatus according to claim 3.   The OB clamp means includes horizontal OB clamp means for clamping the dark level based on a predetermined range of output levels of a horizontal OB pixel portion for each row of the image sensor. The imaging device described.   The imaging apparatus according to claim 5, wherein the light leakage determination unit performs determination for each row of the imaging element.   The OB clamp means changes the OB range for obtaining the clamp level to a range away from the effective pixel portion when the light leakage determination means determines that the light leakage has occurred. The imaging device according to claim 6.   The OB clamp means performs clamping using the clamp level of the row immediately before the light leakage is detected in the row where the light leakage is determined by the light leakage determination means. The imaging device according to claim 6.   The imaging apparatus according to claim 3, wherein the OB clamping unit includes an OB integration unit that performs dark level clamping based on an average output value of a predetermined region of the OB pixel unit.   The OB integration unit is configured to change an OB integration range to a range away from the effective pixel portion when the light leakage determination unit determines that the light leakage occurs. 9. The imaging device according to 9.   The OB integration means performs the OB integration without including the row where the light leakage occurs as the OB integration area when the light leakage determination means determines that the light leakage occurs. The imaging apparatus according to claim 9, wherein the imaging apparatus is characterized. A method of controlling an imaging apparatus that records image data generated by imaging a subject on a recording medium,
An effective pixel portion having a plurality of pixels that convert an optical signal exposed by reflected light from the subject into an electrical signal, and an OB pixel portion that is formed adjacent to the effective pixel portion and whose front surface is shielded from light An OB clamping step of determining a dark level of the image data based on an output level in the OB pixel unit,
An OB pixel portion change detection step for detecting that an output level in the OB pixel portion is changed according to a distance from the effective pixel portion;
The method for controlling an imaging apparatus, wherein the OB clamping step changes an OB region for calculating the dark level in accordance with a detection result obtained by the OB pixel portion change detection step. The OB pixel portion change detection step includes a flat portion extraction step of extracting a range where there is no change in the output level in the OB pixel portion,
The method according to claim 12, wherein the OB clamping step determines a clamping level based on an output level of an OB range extracted by the flat portion extraction step.   The OB pixel portion change detection step is a light leakage determination step of determining that light leakage to the OB pixel portion occurs when an output level increases as the effective pixel portion approaches the OB pixel portion. The method of controlling an imaging apparatus according to claim 12, comprising:   The OB clamping step determines the clamping level based on the output level of the OB range away from the effective pixel portion when the light leakage determining step determines that the light leakage has occurred. The method for controlling an imaging apparatus according to claim 14.   The OB clamping step includes a horizontal OB clamping step of clamping the dark level based on an output level of a predetermined range of a horizontal OB pixel portion for each row of the image pickup device. A control method for the imaging apparatus according to the description.   The method according to claim 16, wherein the light leakage determination step performs determination for each row of the image sensor.   In the OB clamping step, when it is determined in the light leakage determination step that the light leakage has occurred, the OB range for obtaining the clamping level is changed to a range away from the effective pixel portion. The control method of an imaging device according to claim 17.   In the OB clamping step, in the row where the light leakage is determined by the light leakage determination step, clamping is performed using the clamping level of the row immediately before the light leakage is detected. An image pickup apparatus control method according to claim 17.   The method according to claim 14, wherein the OB clamping step includes an OB integration step of performing dark level clamping based on an average output value of a predetermined region of the OB pixel unit.   The OB integration step changes an OB integration range to a range away from the effective pixel portion when the light leakage determination step determines that the light leakage has occurred. 20. A method for controlling the imaging apparatus according to 20.   In the OB integration step, when it is determined in the light leakage determination step that the light leakage has occurred, the OB integration step includes performing the OB integration without including the row in which the light leakage occurs as the OB integration region. 21. A method for controlling an imaging apparatus according to claim 20, wherein:

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