JP2013118563A - Imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress possibility of failure in dark current correction.SOLUTION: An imaging apparatus includes:imaging sections (50, 80 and 70) which image a subject and generate an image signal corresponding to the subject; a storage section (90) which stores information showing a relation between a drive condition of the imaging section upon imaging and a dark current component of the image signal which the imaging section generates upon imaging; a calculation section (90B) which calculates the dark current component of the image signal which the imaging section generates upon imaging on the basis of the information which the storage section stores; and a correction section (90A) which corrects a dark current of the image signal with the dark current component which the calculation section calculates.

Description

  The present invention relates to dark current correction of an image sensor.

  Patent Document 1 discloses an image pickup device in which an optical black region (Optical Black region) is provided around an effective pixel region. An imaging apparatus provided with this imaging element calculates a dark current component generated in an effective pixel area based on a signal in an optical black area.

JP 2009-033321 A

  However, if an image of an extremely bright object such as the sun or a light source is formed in the effective pixel area, noise light may leak from the formation area toward the optical black area, so the calculation fails. There is a high possibility of doing.

  SUMMARY An advantage of some aspects of the invention is that it provides an imaging apparatus that can reduce the possibility of dark current correction failure.

  The imaging apparatus of the present invention captures an object and generates an image signal corresponding to the object, a driving condition of the imaging unit at the time of imaging, and darkness of an image signal generated by the imaging unit at the time of imaging. Based on the storage unit that stores information indicating the relationship with the current component, the driving conditions of the imaging unit at the time of imaging, and the information stored in the storage unit, the image signal generated by the imaging unit at the time of imaging A calculation unit that calculates a dark current component; and a correction unit that performs dark current correction of the image signal using the dark current component calculated by the calculation unit.

  According to the present invention, an imaging apparatus that can suppress the possibility of dark current correction failure is realized.

It is a block diagram of the digital camera of the embodiment. It is a block diagram regarding dark current correction. It is a timing chart of each part at the time of acquisition of a through image. It is a timing chart of each part at the time of acquisition of a detailed image. It is a figure which shows the dark current component which generate | occur | produces in an effective pixel area | region at the time of acquisition of a detailed image. It is a figure which shows the dark current component (when (alpha) changes) generated in an effective pixel area | region at the time of acquisition of a detailed image. It is a figure which shows the dark current component (when (beta) changes) generated in an effective pixel area | region at the time of acquisition of a detailed image. It is a figure which shows the content of the alpha table. It is a figure which shows the content of (beta) -table. It is a figure which shows the content of the g-table. It is an operation | movement flowchart of the image processing engine 90 regarding imaging | photography.

[Embodiment]
Hereinafter, a digital camera will be described as an embodiment of the present invention.

  FIG. 1 is a configuration diagram of a digital camera according to the present embodiment. As shown in FIG. 1, the digital camera 10 includes a photographic lens 20, a mechanical shutter 30, an image sensor 50, a timing generator (TG) 70, an analog front end (AFE) 80, an image processing engine 90, a motor driver 110, and a temperature detector. 120, a buffer memory 130, a display unit 140, an operation unit 150, a removable memory 160, and the like.

  The photographing lens 20 forms an image of a light beam emitted from the subject and forms a subject image on the effective pixel area of the image sensor 50.

  The mechanical shutter 30 is disposed on the optical path between the photographic lens 20 and the image sensor 50, and opens and closes the optical path of the light beam toward the image sensor 50 as necessary. The mechanical shutter 30 is a lens shutter disposed at a position away from the image sensor 50 by a certain distance or a focal plane shutter disposed in the vicinity of the image sensor 50.

  The image sensor 50 is a CMOS image sensor in which pixels that generate signals according to incident light are arranged in a two-dimensional matrix, and here, a CMOS image sensor that sequentially performs signal reset and signal readout for each horizontal pixel row. And However, the image sensor 50 of the present embodiment can match the signal reset timing among all the pixels as necessary.

  Note that it is desirable that the imaging device 50 is provided with an ineffective pixel region (optical black region) where light does not enter around an incident region (effective pixel region) of light from the subject. This optical black area can be used for setting the black level. However, in the present embodiment, dark current correction can be performed without using this optical black region.

  In response to an instruction from the image processing engine 90, the TG 70 supplies a drive signal to the image sensor 50 and the mechanical shutter 30, and supplies a synchronization signal to the AFE 80 and the image processing engine 90.

  The TG 70 switches the drive mode of the image sensor 50 between the draft mode (high-speed read mode) and the frame mode (all pixel read mode) by switching the pattern of the drive signal supplied to the image sensor 50. Can do. The draft mode is a drive mode for acquiring a through image for confirmation before photographing, and the frame mode is a drive mode for acquiring a detailed image for storage.

  Further, the TG 70 switches the pattern of the drive signal supplied to the mechanical shutter 30 to change the opening / closing pattern of the mechanical shutter 30 between the opening / closing pattern for acquiring a through image and the opening / closing pattern for acquiring a detailed image. Can be switched.

  The TG 70 can also switch the exposure time per frame of the image sensor 50 by switching the pattern of the drive signal supplied to the image sensor 50. Incidentally, the exposure time is set to a value corresponding to the Tv value designated by the image processing engine 90 (= Tv value input by the user or Tv value calculated by automatic exposure calculation).

  The AFE 80 performs pipeline processing on the analog signal output from the image sensor 50. The AFE 80 includes a CDS circuit, a gain circuit, an A / D conversion circuit, and the like. The CDS circuit removes the noise component of the analog signal output from the image sensor 50 by correlated double sampling, and the gain circuit The analog signal after noise removal is amplified, and the A / D conversion circuit converts the amplified analog signal into a digital signal.

  The gain of the AFE 80 (the signal amplification factor of the gain circuit) is set to a value corresponding to the Sv value designated by the image processing engine 90 (= the Sv value input by the user or the Sv value calculated by automatic exposure calculation). The The Sv value input by the user is a so-called “ISO sensitivity”.

  In response to an instruction from the image processing engine 90, the motor driver 110 drives at least a part of the photographing lens 20 in the optical axis direction, and adjusts the focus position, the zoom position, and the like of the photographing lens 20. In addition, the motor driver 110 adjusts the aperture diameter of the photographing lens 20 in accordance with the Av value specified by the image processing engine 90 (= the Av value input by the user or the Av value calculated by automatic exposure calculation).

  The temperature detector 120 is a temperature sensor provided in the vicinity of the effective pixel region of the image sensor 50 or in the vicinity of the image sensor 50, and indirectly or directly determines the temperature T of the effective pixel region of the image sensor 50. To detect.

  The buffer memory 130 stores the digital signal transferred from the AFE 80 to the image processing engine 90. When this accumulation is performed over a signal reading period for one frame of the image sensor 50, a digital signal for one frame (image data for one frame) is accumulated in the buffer memory 130.

  The display unit 140 displays various image data in accordance with instructions from the image processing engine 90. The image data displayed by the display unit 140 includes image data of a through image acquired by the image sensor 50, image data of a detailed image acquired by the image sensor 50, image data stored in the removable memory 160, and an image processing engine 90. There is image data for menu display created by.

  The operation unit 150 includes various switches that can be operated by the user, such as a release button and a menu button. The user can input various instructions to the digital camera 10 via the operation unit 150. For example, the user can designate the photometric area at the time of acquiring the detailed image to the digital camera 10.

  The removable memory 160 is a non-volatile memory that can store image data acquired by the digital camera 10 and image data acquired by another digital camera over a long period of time.

  The image processing engine 90 controls each unit of the digital camera 10 in accordance with an instruction input from the user via the operation unit 150 and a program (not shown). The image processing engine 90 performs signal processing (dark current correction or the like) on the digital signal sent from the AFE 80, or performs image processing (gradation conversion, color conversion, White balance adjustment, etc.).

  In the dark current correction, the image processing engine 90 functions as a dark current correction circuit 90A and a dark current calculation circuit 90B. As shown in FIG. 2, the dark current correction circuit 90 </ b> A is a circuit that subtracts the dark current component N (v) from the digital signal S (v) output from the AFE 80. The dark current calculation circuit 90B is a circuit that calculates the dark current component N (v) to be subtracted by the dark current calculation circuit 90B based on the driving condition of the image sensor 50.

  FIG. 3 is a timing chart of each unit at the time of obtaining a through image. 3A shows the frame period, FIG. 3B shows the signal accumulation period of each horizontal pixel row of the image sensor 50, and FIG. 3C shows opening and closing of the mechanical shutter 30. The pattern is shown. Note that the white portions in FIG. 3B indicate signal accumulation periods, and the solid portions indicate signal readout periods.

  As shown in FIG. 3, when acquiring a through image, the mechanical shutter 30 is kept open in order to maintain the frame rate, and the exposure period of the image sensor 50 is the timing at which the signal of the image sensor 50 is reset. And the timing at which the signal of the image sensor 50 is read out.

  Specifically, when a through image is acquired, first, the signals of the horizontal pixel rows of the image sensor 50 are reset in the order of the row numbers in a state where the mechanical shutter 30 is opened (reference a in FIG. 3) (FIG. 3). B). Therefore, each horizontal pixel row starts signal accumulation sequentially. Thereafter, the signals in each horizontal pixel row are read in line order (reference c in FIG. 3).

  Therefore, at the time of acquiring a through image, the exposure period of the image sensor 50 is a period from the timing when the signal is reset (symbol b) to the timing when the signal reading is started (symbol c). The length of the exposure period (exposure time) corresponds to the Tv value.

  Although not shown in FIG. 3, when the through image is acquired, the drive mode of the image sensor 50 is set to the draft mode, so that the signal read source is not all the pixels on the image sensor 50 but a part thereof. It is assumed that the number of pixels is limited (thinning readout).

  As described above, when a through image is acquired, the exposure time is the same among all horizontal pixel rows, but the start timing of the exposure period is delayed as the horizontal pixel row has a larger row number. That is, the shutter method at the time of acquiring a through image is a so-called rolling shutter method.

  FIG. 4 is a timing chart of each part at the time of acquiring a detailed image. 4A shows the frame period, FIG. 4B shows the signal accumulation period of each horizontal pixel row of the image sensor 50, and FIG. 4C shows the opening / closing of the mechanical shutter 30. The pattern is shown. Note that a white portion in FIG. 4B indicates a signal accumulation period, and a solid portion indicates a signal readout period.

  As shown in FIG. 4, when acquiring a detailed image, in order to make the exposure period of the effective pixel area of the image sensor 50 coincide between the pixels, the exposure period of the image sensor 50 is the timing when the signal of the image sensor 50 is reset. Control is performed in combination with the timing at which the mechanical shutter 30 is closed.

  Specifically, when acquiring a detailed image, first, the signals of the horizontal pixel rows of the image sensor 50 are reset all at once with the mechanical shutter 30 opened (reference symbol a in FIG. 4) (reference symbol in FIG. 3). b). Therefore, each horizontal pixel row starts signal accumulation simultaneously. Thereafter, the mechanical shutter 30 is closed (reference c in FIG. 4). Here, it can be considered that the time required for closing the mechanical shutter 30 is extremely short. Therefore, the exposure period of each horizontal pixel row ends at the same time. Thereafter, the signals of the horizontal pixel rows are read in the order of the row numbers (reference numeral d in FIG. 4).

  Therefore, when acquiring a detailed image, the exposure period of the effective pixel region is a period from the timing at which the signal is reset (symbol b) to the timing at which the mechanical shutter 30 is closed (symbol c). The length of the exposure period (exposure time) corresponds to the Tv value.

  Although not shown in FIG. 4, when a detailed image is acquired, the drive mode of the image sensor 50 is set to the frame mode, so that the signal reading source is set to all pixels on the image sensor 50. Suppose that all pixels are read out.

  As described above, when acquiring a detailed image, the exposure time is the same among all the horizontal pixel rows, and the start timing of the exposure period is also the same. That is, the shutter method at the time of acquiring a detailed image is a so-called global shutter method.

  However, since the readout of the signal is started earlier as the horizontal pixel row has a smaller row number, the length of the signal accumulation period (signal accumulation time) is obtained as the horizontal pixel row has a smaller row number when acquiring a detailed image according to the present embodiment. Becomes shorter. Thus, when the signal accumulation time is non-uniform on the effective pixel region of the image sensor 50, the dark current component generated in the effective pixel region is also non-uniform.

  However, the distribution of the dark current component in the effective pixel region is considered to have a shape corresponding to the distribution of the signal accumulation time in the effective pixel region.

  Therefore, when the signal accumulation time is shorter as the horizontal pixel row has a smaller row number as in the case of acquiring a detailed image of the present embodiment, the dark current component included in the horizontal pixel row having a smaller row number decreases. Conceivable.

  Actually, the dark current component generated in the effective pixel area when acquiring the detailed image corresponds to the distribution of the signal accumulation time in the effective pixel area as shown in FIG. The horizontal axis in FIG. 5 indicates the row number of the horizontal pixel row, and the vertical axis in FIG. 5 indicates the dark current component n (v) generated in the vth horizontal pixel row. In this case, the dark current component n (v) is represented by a linear function of v as shown in the following formula (1).

n (v) = αv + β (1)
In this equation (1), “β” is a dark current component (DC component) common among the pixels in the effective pixel region, and “αv” in equation (1) is not common among the pixels in the effective pixel region. It is a dark current component (non-DC component).

  Here, when the temperature T changes, the coefficient α in the equation (1) changes variously as shown in FIG. Further, when the temperature T changes, the coefficient β in the equation (1) also changes variously as shown in FIG. In addition, the coefficient β depends not only on the temperature T but also on the exposure time (that is, the Tv value) of the image sensor 50 (specifically, the coefficient β increases as the temperature T increases, and the Tv value increases). growing.).

  Focusing on the horizontal pixel row after passing through the AFE 80, the dark current component included in the horizontal pixel row should increase as the gain of the AFE 80 increases (that is, as the Sv value increases). Therefore, the dark current component N (v) superimposed on the vth horizontal pixel row after passing through the AFE can be expressed by Expression (2).

N (v) = g (α · v + β) (2)
However, the coefficient g is a coefficient that increases as the Sv value increases.

  Therefore, the image processing engine 90 of the present embodiment stores parameter tables as shown in FIGS. 8, 9, and 10 in advance. The table shown in FIG. 8 is a table (α-table) for determining the coefficient α, and the table shown in FIG. 9 is a table (β-table) for determining the coefficient β, as shown in FIG. The table is a table (g-table) for determining the coefficient g.

  As shown in FIG. 8, the α-table is a table that stores the optimum value of the coefficient α for each temperature T. Note that, as the temperature T is higher, the change width of the coefficient α due to the change in the temperature T tends to be larger. Therefore, in the α-table, more values are prepared for the coefficient α when the temperature T is higher. It is desirable. Further, as shown in FIG. 9, the β-table is a table that stores the optimum value of the coefficient β for each combination of the temperature T and the Tv value. Note that, as the temperature T is higher, the change width of the coefficient β due to the change of the temperature T tends to be larger. Therefore, in the β-table, more values are prepared for the coefficient β when the temperature T is higher. It is desirable. Also, as shown in FIG. 10, the g-table is a table that stores the optimum value of the coefficient g for each Sv value.

  FIG. 11 is an operation flowchart of the image processing engine 90 relating to shooting. Hereinafter, each step of FIG. 11 will be described.

  Step S10: The image processing engine 90 causes the imaging unit to start acquiring a through image (note that the imaging unit refers to elements related to imaging such as the TG 70, the imaging device 50, the mechanical shutter 30, and the AFE 80). ).

  At this time, the digital signal of the through image output from the AFE 80 is sequentially input to the image processing engine 90. The image processing engine 90 performs predetermined signal processing (live view signal processing) on the digital signal input from the AFE 80 and sends the digital signal to the display unit 140. As a result, a live view image (real-time image) of the subject is displayed on the display unit 140. Here, for simplicity, it is assumed that dark current correction is not included in the signal processing in this step.

  Step S11: The image processing engine 90 determines whether or not the release button is half-pressed based on the state of the operation unit 150. If the release button is half-pressed, the process proceeds to step S12.

  Step S12: The image processing engine 90 sets the final value y of the loop count v to the same value as the total number V of horizontal pixel rows in the detailed image.

  Step S13: The image processing engine 90 refers to the output of the temperature detector 120 and detects the current temperature T.

  Step S14: The image processing engine 90 refers to the digital signal corresponding to the photometry area designated in advance by the user among the digital signals of the through image at the time when the release button is pressed halfway, thereby evaluating the brightness of the through image. Calculate the value. Further, the image processing engine 90 performs an automatic exposure calculation based on the luminance evaluation value, and determines a Tv value, an Sv value, and an Av value to be set when a detailed image is acquired.

  Step S15: The image processing engine 90 refers to the α-table (FIG. 8) according to the detected temperature T, thereby determining the value of the coefficient α to be used in the dark current correction of the detailed image.

  Further, the image processing engine 90 refers to the β-table (FIG. 9) according to the combination of the detected temperature T and the determined Tv value, so that the value of the coefficient β to be used in the dark current correction of the detailed image. To decide.

  Further, the image processing engine 90 refers to the g-table (FIG. 10) according to the determined Sv value, thereby determining the value of the coefficient g to be used in the dark current correction of the detailed image.

  Step S16: The image processing engine 90 determines whether or not the release button has been fully pressed. If the release button has been fully pressed, the process proceeds to step S18. If not, the process proceeds to step S17.

  Step S17: The image processing engine 90 determines whether or not the half-press of the release button has been released. If released, the process proceeds to step S11. If not released, the process proceeds to step S16.

  Step S18: The image processing engine 90 designates the determined Sv value, Tv value, and Av value to the corresponding part (AFE80, TG70, motor driver 110) of the imaging unit, and then acquires a detailed image for the imaging unit. Let it be done. At this time, the digital signal of the detailed image output from the AFE 80 is sequentially input to the image processing engine 90.

  Step S19: The image processing engine 90 sets the loop count v to an initial value 1.

  Step S20: The image processing engine 90 recognizes the timing at which the signal is read from the v-th horizontal pixel row of the image sensor 50 based on the synchronization signal supplied from the TG 70.

  Step S21: The image processing engine 90 causes the dark current calculation circuit 90B to calculate the dark current component N (v) of the vth horizontal pixel row. The dark current calculation circuit 90B calculates the dark current component N (v) by the above-described equation (2) and supplies it to the dark current correction circuit 90A. In the calculation, the dark current calculation circuit 90B uses the values of the coefficients α, β, and g determined in step S15.

  Step S22: The image processing engine 90 causes the dark current correction circuit 90A to execute dark current correction at the timing when the digital signal S (v) of the vth horizontal pixel row is input to the image processing engine 90. The dark current correction circuit 90A generates a digital signal S ′ (v) after dark current correction by subtracting the dark current component N (v) given from the dark current calculation circuit 90B from the digital signal S (v). To do.

  Step S23: The image processing engine 90 writes the digital signal S ′ (v) after dark current correction into the buffer memory 130 as a digital signal of the vth horizontal pixel row.

  Step S24: The image processing engine 90 determines whether or not the loop count v has reached the final value y. If it has not, the process proceeds to step S25, and if it has reached, the process proceeds to step S26.

  Step S25: The image processing engine 90 increments the loop count v and then returns to step S20. Therefore, the loop of steps S20 to S23 is sequentially executed for all horizontal pixel rows.

  Step S26: The image processing engine 90 performs predetermined image processing (image processing for storage) on the digital signals S ′ (v) of all horizontal pixel rows written in the buffer memory 130, that is, one frame of detailed images. ), The data is written to the removable memory 160, and the flow ends.

  As described above, the image processing engine 90 according to the present embodiment has the driving conditions of the imaging unit (elements related to imaging such as the TG 70, the imaging element 50, the mechanical shutter 30, and the AFE 80) at the time of imaging and the effective pixel area of the imaging unit at the time of imaging. Based on the storage unit that stores information indicating the relationship with the dark current component of the image signal generated by the image signal, the driving conditions of the imaging unit at the time of imaging, and the information stored in the storage unit, the imaging at the time of imaging A calculation unit (dark current calculation circuit 90B) that calculates a dark current component of the image signal generated by the effective pixel region of the unit, and a correction unit that corrects the dark current of the image signal using the dark current component calculated by the calculation unit ( Dark current correction circuit 90A).

  Therefore, the image processing engine 90 of this embodiment does not need to use the optical black area for dark current correction. Therefore, even if a high-luminance image is formed in the effective pixel area and noise light leaks into the optical black area, the image processing engine 90 of the present embodiment fails in the dark current correction. There is no.

  The information includes at least one of a temperature (T) of the imaging unit at the time of imaging, an exposure time (Tv) of the imaging unit at the time of imaging, and a signal amplification factor (Sv) of the imaging unit at the time of imaging. The relationship between the said one driving condition and the said dark current component is shown.

  Therefore, the image processing engine 90 according to the present embodiment can correctly correct the dark current component that changes according to the driving condition (at least one of temperature, exposure time, and signal amplification factor) of the imaging unit.

  Further, the imaging unit can arrange pixels that generate an image signal according to incident light in a two-dimensional matrix, and can set a signal accumulation time of the pixels for each pixel row, and the arithmetic unit Performs the calculation of the dark current component for each pixel row of the imaging unit.

  Further, the information includes first information (gα) indicating a relationship between a dark current component that is not common between pixel rows of the imaging unit and the driving condition, and a dark current component that is common between pixel rows of the imaging unit, Second information (gβ) indicating a relationship with the driving condition is included.

  The value of the first information (gα) depends on at least one of the temperature (T) of the imaging unit and the signal amplification factor (Sv) of the imaging unit, and the second information (gβ) The value of depends on at least one of the temperature (T) of the imaging unit, the signal amplification factor (Sv) of the imaging unit, and the exposure time (Tv) of the imaging unit.

  Therefore, the image processing engine 90 of the present embodiment can correctly correct the dark current component having a value that varies depending on the driving condition of the imaging unit and varies depending on the pixel row.

  In addition, the storage unit stores at least a part of the first information (gα) and the second information (gβ) as a parameter table.

  Therefore, the image processing engine 90 according to the present embodiment can speed up the calculation of the dark current component and increase the speed of dark current correction.

[Supplement of embodiment]
In the α-table (FIG. 8) and β-table (FIG. 9) of the above embodiment, the number of steps in the temperature direction (T direction) is set to 4, but the change width of the dark current component due to the temperature change is large. In this case, the number of stages may be 5 or more.

  Further, in the β-table (FIG. 9) of the above embodiment, the number of steps in the exposure time direction (Tv value direction) is 14, but when the change width of the dark current component due to the change in Tv value is large, The number of steps may be 15 or more.

  In the g-table (FIG. 10) of the above embodiment, the number of steps in the sensitivity direction (Sv value direction) is set to 7. However, when the change width of the dark current component due to the change in the Sv value is large, that step. The number may be 8 or more.

  Further, the image processing engine 90 of the above embodiment omits the dark current correction for the through image (see step S10 described above), but may perform the dark current correction for the through image. However, when acquiring a through image, the signal accumulation time in the image sensor 50 is uniform, so that the dark current component in the effective pixel region can also be regarded as uniform. Therefore, in the dark current correction for the through image, if the dark current component common to the pixels in the effective pixel region is calculated in a lump by using the formula (N = gβ) in which the coefficient α is zero in the formula (2). Good.

  In the imaging unit of the above embodiment, the signal accumulation time at the time of acquiring the detailed image is set for each pixel row, and the signal accumulation time at the time of acquiring the through image is set in common between the pixels. May always be set in common between pixels. In this case, the information stored in the storage unit may be only the second information (gβ).

  In the above embodiment, the temperature of the effective pixel region is detected. However, the temperature distribution of the effective pixel region may be detected instead of the temperature of the effective pixel region. For example, when there is a heat source (a place where heat is likely to be generated) on the image sensor 50, the temperature detection unit 120 is disposed in the vicinity of the heat source, and the temperature at each position in the effective pixel region is determined from the temperature detection unit 120. You may calculate based on the distance to each position, and the output of the temperature detection part 120. FIG. Alternatively, the temperature distribution of the effective pixel region may be detected by disposing the temperature detection unit 120 at each of a plurality of positions near the effective pixel region.

  In addition, when the temperature distribution of the effective pixel region is detected, in the calculation of the dark current component of the effective pixel region, the distribution of the dark current component of the effective pixel region is the distribution of the signal accumulation time of the effective pixel region and the effective pixel region. It can be considered that it is determined by both the temperature distribution.

  In the image processing engine 90 of the above embodiment, the dark current correction timing is set every time a digital signal (a digital signal in a horizontal pixel row) is output from the AFE 80. However, the digital signal for one frame is stored in the buffer memory 130. It may be after it has been accumulated. However, if the dark current correction timing is set every time a digital signal is output from the AFE 80, the waiting time of the user at the time of shooting can be shortened.

  Further, the image processing engine 90 of the above embodiment has determined all of the Tv value, Av value, and Sv value to be set at the time of acquiring the detailed image by the automatic exposure calculation, but at least the Tv value, Av value, and Sv value are determined. One may be specified by the user.

  In the image sensor 50 of the above embodiment, the signal is read for each pixel row, but may be read for each region or for each pixel. In any case, in the calculation of the dark current component in the effective pixel region, the dark current component in the effective pixel region is obtained by calculating the signal accumulation time distribution in the effective pixel region and the temperature distribution (or effective pixel region) in the effective pixel region. The temperature is determined by the

  DESCRIPTION OF SYMBOLS 10 ... Digital camera, 20 ... Shooting lens, 30 ... Mechanical shutter, 50 ... Image sensor, 70 ... Timing generator (TG), 80 ... Analog front end (AFE), 90 ... Image processing engine, 110 ... Motor driver, 120 ... Temperature detection unit, 130 ... buffer memory, 140 ... display unit, 150 ... operation unit, 160 ... removable memory, 90A ... dark current correction circuit, 90B ... dark current calculation circuit

Claims (10)

An imaging unit that images a subject and generates an image signal corresponding to the subject;
A storage unit that stores information indicating a relationship between a driving condition of the imaging unit at the time of imaging and a dark current component of an image signal generated by the imaging unit at the time of imaging;
A calculation unit that calculates a dark current component of an image signal generated by the imaging unit at the time of imaging based on a driving condition of the imaging unit at the time of imaging and the information stored in the storage unit;
A correction unit that performs dark current correction of the image signal using the dark current component calculated by the calculation unit;
An imaging apparatus comprising: The imaging device according to claim 1,
The information is
The driving condition consisting of at least one of the temperature of the imaging unit during imaging, the exposure time of the imaging unit during imaging, and the signal amplification factor of the imaging unit during imaging, and the dark current component An imaging apparatus characterized by showing a relationship. The imaging device according to claim 2,
The imaging unit
It is possible to arrange pixels that generate an image signal according to incident light in a two-dimensional matrix, and to set the signal accumulation time of these pixels for each pixel row,
The computing unit is
The imaging apparatus, wherein the dark current component is calculated for each pixel row of the imaging unit. The imaging device according to claim 3.
The information includes
First information indicating a relationship between a dark current component that is not common between pixel rows of the imaging unit and the driving condition;
Second information indicating a relationship between a dark current component common to the pixel rows of the imaging unit and the driving condition;
An image pickup apparatus comprising: The imaging apparatus according to claim 4,
The storage unit
Storing the first information as a value depending on at least one of a temperature of the imaging unit and a signal amplification factor of the imaging unit;
The second apparatus stores the second information as a value depending on at least one of a temperature of the imaging unit, a signal amplification factor of the imaging unit, and an exposure time of the imaging unit. The imaging apparatus according to claim 5,
The storage unit
At least a part of the first information and the second information is stored as a parameter table. The imaging device according to claim 2,
The imaging unit
It is possible to arrange pixels that generate image signals according to incident light in a two-dimensional matrix, and to set the signal accumulation time of these pixels in common between the pixels,
The computing unit is
The imaging apparatus, wherein the dark current component is calculated for all pixels of the imaging unit. The imaging apparatus according to claim 7,
The information includes
The imaging apparatus characterized by including the 2nd information which shows the relationship between the dark current component common between the pixels of the said imaging part, and the said drive condition. The imaging device according to claim 8,
The storage unit
The second apparatus stores the second information as a value depending on at least one of a temperature of the imaging unit, a signal amplification factor of the imaging unit, and an exposure time of the imaging unit. The imaging device according to claim 9,
The storage unit
An imaging apparatus, wherein at least a part of the second information is stored as a parameter table.

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