WO2018124056A1

WO2018124056A1 - Imaging device and control method therefor

Info

Publication number: WO2018124056A1
Application number: PCT/JP2017/046600
Authority: WO
Inventors: 直人末廣
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2016-12-27
Filing date: 2017-12-26
Publication date: 2018-07-05
Also published as: JP6748979B2; JP2018107730A

Abstract

This imaging device (100) is provided with: an imaging element (101) which can be non-destructively read; an imaging system (106) which focuses light on the imaging element (101); a light shielding unit (107) which shields the light of the imaging system (106); and a correction unit (105) which generates a corrected image (142) by subtracting a correcting image (141) from a main image (121) obtained by the imaging element (101). The correction unit (105) uses non-destructive reading to acquire a plurality of light-shielded images (131), which are obtained by the imaging element (101) as a result of one exposure in a light-shielded state, and which each have different exposure times, and uses at least one of the plurality of light-shielded images (131) to generate the correcting image (141).

Description

Imaging apparatus and control method thereof

The present disclosure relates to an imaging apparatus and a control method thereof.

A technique described in Patent Document 1 is known as an image sensor using an organic photoelectric conversion element.

JP 2008-042180 A

In the imaging apparatus, processing for correcting a change in black level caused by dark current is performed. Specifically, the imaging device reduces the influence of dark current by subtracting a light-shielded image taken in a light-shielded state from the main image.

However, the dark current amount may change due to, for example, a change in temperature between when the main image is captured and when the light-shielded image is captured. In this case, the influence of dark current cannot be completely eliminated by the above correction.

Therefore, an object of the present disclosure is to provide an imaging apparatus that can reduce the influence of the dark current amount or a control method thereof.

An imaging apparatus according to an aspect of the present disclosure includes: an imaging element that can perform nondestructive reading; an imaging system that collects light on the imaging element; a light-blocking unit that blocks light from the imaging system; and the imaging element. A correction unit that generates a corrected image by subtracting a correction image from the obtained main image, and the correction unit is obtained by the imaging device by one exposure in a light-shielding state, and each has a different exposure time. A plurality of shaded images are acquired using nondestructive readout, and the correction image is generated using at least one of the plurality of shaded images.

The present disclosure can provide an imaging apparatus or a control method thereof that can reduce the influence of the dark current amount.

FIG. 1 is a block diagram of the imaging apparatus according to the first embodiment. FIG. 2A is a diagram illustrating an appearance example of the imaging apparatus according to Embodiment 1. FIG. 2B is a diagram illustrating an appearance example of the imaging apparatus according to Embodiment 1. FIG. 3 is a diagram illustrating a configuration of the image sensor according to the first embodiment. FIG. 4 is a circuit diagram illustrating a configuration of a pixel according to Embodiment 1. FIG. 5 is a flowchart illustrating the operation of the imaging apparatus according to the first embodiment. FIG. 6 is a diagram illustrating the operation of the imaging apparatus according to the first embodiment. FIG. 7 is a diagram illustrating an example of the main image according to the first embodiment. FIG. 8 is a diagram illustrating an example of a plurality of light-shielded images according to the first embodiment. FIG. 9 is a diagram illustrating a calculation process of the corrected image according to the first embodiment. FIG. 10 is a flowchart illustrating the operation of the imaging apparatus according to the second embodiment. FIG. 11 is a diagram illustrating the operation of the imaging apparatus according to the second embodiment. FIG. 12 is a flowchart illustrating the operation of the imaging apparatus according to the modification of the second embodiment. FIG. 13 is a diagram illustrating the operation of the imaging apparatus according to the modification of the second embodiment. FIG. 14 is a flowchart illustrating the operation of the imaging apparatus according to the third embodiment. FIG. 15 is a diagram illustrating the operation of the imaging apparatus according to the third embodiment. FIG. 16 is a flowchart illustrating the operation of the imaging apparatus according to the modification of the third embodiment. FIG. 17 is a diagram illustrating the operation of the imaging apparatus according to the modification of the third embodiment.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Each of the embodiments described below shows a preferred specific example of the present disclosure. Therefore, the numerical values, shapes, materials, components, component arrangement positions, connection forms, and the like shown in the following embodiments are merely examples, and are not intended to limit the present disclosure. Therefore, among the constituent elements in the following embodiments, constituent elements that are not described in the independent claims indicating the highest concept of the present disclosure are described as arbitrary constituent elements.

Each figure is a schematic diagram and is not necessarily shown strictly. Moreover, in each figure, the same code | symbol is attached | subjected to the substantially same structure, The overlapping description is abbreviate | omitted or simplified.

(Embodiment 1)
[Configuration of imaging device]
First, the configuration of the imaging device according to the embodiment of the present disclosure will be described. FIG. 1 is a block diagram illustrating a configuration of an imaging apparatus 100 according to the present embodiment. 2A and 2B are diagrams illustrating an example of the appearance of the imaging apparatus 100. FIG. For example, as illustrated in FIGS. 2A and 2B, the imaging apparatus 100 is a camera such as a digital still camera or a digital video camera.

1 includes an imaging element 101, a control unit 102, a display unit 103, a storage unit 104, an imaging system 106, and a light shielding unit 107. The imaging device 101 is a solid-state imaging device (solid-state imaging device) that converts incident light into an electrical signal (image) and outputs the obtained electrical signal. For example, the imaging device 101 is an organic sensor using an organic photoelectric conversion device.

The control unit 102 controls the image sensor 101. In addition, the control unit 102 performs various signal processing on the image obtained by the imaging element 101, and displays the obtained image on the display unit 103 or stores it in the storage unit 104. Note that the image output from the control unit 102 may be output to the outside of the imaging apparatus 100 via an input / output interface (not shown).

In addition, the control unit 102 includes a correction unit 105 that corrects an image obtained by the image sensor 101.

The imaging system 106 includes, for example, one or a plurality of lenses, and condenses light from the outside of the imaging apparatus 100 on the imaging element 101.

The light shielding unit 107 is, for example, a mechanical shutter, and shields light from the imaging system 106.

[Configuration of image sensor]
Next, the configuration of the image sensor 101 will be described. FIG. 3 is a block diagram illustrating a configuration of the image sensor 101.

3 includes a plurality of pixels (unit pixel cells) 201 arranged in a matrix, a vertical scanning unit 202, a column signal processing unit 203, a horizontal readout unit 204, and a row. A plurality of reset control lines 205, a plurality of address control lines 206 provided for each row, a plurality of vertical signal lines 207 provided for each column, and a horizontal output terminal 208.

Each of the plurality of pixels 201 outputs a signal corresponding to the incident light to the vertical signal line 207 provided in the corresponding column.

The vertical scanning unit 202 resets the plurality of pixels 201 via the plurality of reset control lines 205. The vertical scanning unit 202 sequentially selects the plurality of pixels 201 in units of rows via the plurality of address control lines 206.

The column signal processing unit 203 performs signal processing on the signals output to the plurality of vertical signal lines 207, and outputs the plurality of signals obtained by the signal processing to the horizontal reading unit 204. For example, the column signal processing unit 203 performs noise suppression signal processing represented by correlated double sampling, analog / digital conversion processing, and the like.

The horizontal readout unit 204 sequentially outputs a plurality of signals after the signal processing by the plurality of column signal processing units 203 to the horizontal output terminal 208.

Hereinafter, the configuration of the pixel 201 will be described. FIG. 4 is a circuit diagram illustrating a configuration of the pixel 201.

As shown in FIG. 4, the pixel 201 includes a photoelectric conversion unit 211, a charge storage unit 212, a reset transistor 213, an amplification transistor 214 (source follower transistor), and a selection transistor 215.

The photoelectric conversion unit 211 generates signal charges by photoelectrically converting incident light. A voltage Voe is applied to one end of the photoelectric conversion unit 211. Specifically, the photoelectric conversion unit 211 includes a photoelectric conversion layer made of an organic material. The photoelectric conversion layer may include a layer made of an organic material and a layer made of an inorganic material.

The charge storage unit 212 is connected to the photoelectric conversion unit 211 and stores the signal charge generated by the photoelectric conversion unit 211. Note that the charge storage unit 212 may be configured with a parasitic capacitance such as a wiring capacitance instead of a dedicated capacitance element.

The reset transistor 213 is used to reset the potential of the signal charge. The gate of the reset transistor 213 is connected to the reset control line 205, the source is connected to the charge storage unit 212, and the reset voltage Vreset is applied to the drain.

Note that the definitions of drain and source generally depend on circuit operation, and are often not specified from the element structure. In this embodiment, for convenience, one of the source and the drain is referred to as a source and the other of the source and the drain is referred to as a drain. However, in this embodiment, the drain may be replaced with the source and the source may be replaced with the drain.

The amplification transistor 214 amplifies the voltage of the charge storage unit 212 and outputs a signal corresponding to the voltage to the vertical signal line 207. The gate of the amplification transistor 214 is connected to the charge storage unit 212, and the power supply voltage Vdd or the ground voltage Vss is applied to the drain.

The selection transistor 215 is connected in series with the amplification transistor 214, and switches whether to output the signal amplified by the amplification transistor 214 to the vertical signal line 207. The selection transistor 215 has a gate connected to the address control line 206, a drain connected to the source of the amplification transistor 214, and a source connected to the vertical signal line 207.

Further, for example, the voltage Voe, the reset voltage Vreset, and the power supply voltage Vdd are voltages commonly used in all the pixels 201.

The characteristics of the organic sensor include non-destructive readout and electronic ND (Neutral Density) control. Non-destructive reading is a process of reading image data during an exposure period and continuing exposure. In conventional readout (hereinafter referred to as destructive readout), it is necessary to end exposure when performing readout. That is, only one image could be obtained by one exposure. On the other hand, by using nondestructive reading, it is possible to read the image data exposed up to that time during the exposure period and continue the exposure. Thereby, a plurality of images having different exposure times can be obtained by one exposure.

The electronic ND control is a process for electrically controlling the transmittance of the image sensor. Here, the transmittance means the proportion of light that is converted into an electrical signal in the incident light. That is, by setting the transmittance to 0%, it is possible to electrically shield the light. Specifically, the transmittance is controlled by controlling the voltage Voe shown in FIG. Thereby, exposure can be electrically terminated without using a mechanical shutter.

Note that the image sensor 101 includes a mechanical shutter and may use both electronic ND control and light shielding by the mechanical shutter, or may use light shielding by the mechanical shutter without using the electronic ND control.

In addition, here, an example in which the image sensor 101 is an organic sensor will be described. However, the image sensor 101 only needs to realize nondestructive reading or electronic ND control, and may be other than an organic sensor. That is, the photoelectric conversion layer included in the photoelectric conversion unit 211 may be made of an inorganic material. For example, the photoelectric conversion layer may be made of amorphous silicon or chalcopyrite semiconductor.

[Operation of imaging device]
Next, the operation of the imaging apparatus 100 according to the present embodiment will be described. FIG. 5 is a flowchart showing an operation flow of the imaging apparatus 100. FIG. 6 is a diagram for explaining the operation of the imaging apparatus 100. For example, this operation is used when a night sky or a night view is exposed for a long time.

As shown in FIG. 5, the imaging device 100 first captures the main image 121 (S101). Specifically, as shown in FIG. 6, normal exposure is performed from time t1, and then the main image 121 is read by destructive reading.

Next, the imaging apparatus 100 starts light-shielding exposure for generating the correction image 141 at time t2 (S102). Specifically, the light-shielding exposure is to perform exposure in a light-shielded state. For example, light shielding is performed by the above-described electronic ND control or a mechanical shutter. Further, the light-shielded image 131 photographed in such a light-shielded state shows a pixel value (luminance value) corresponding to the dark current amount.

Next, the imaging apparatus 100 generates a plurality of light-shielded images 131 by performing non-destructive readout a predetermined number of times during the light-shielding exposure period (S103). Specifically, the imaging apparatus 100 repeatedly performs nondestructive reading at a predetermined cycle T4 after a predetermined time T3 has elapsed after the start of light-shielding exposure.

Further, the exposure time T2 of the light-shielding exposure is predetermined and is longer than the main exposure time T1, for example.

FIG. 7 is a diagram illustrating an example of the main image 121. FIG. 8 is a diagram illustrating an example of the plurality of light-shielded images 131. As shown in FIG. 7, the main image 121 includes an effective area 122 for outputting an electrical signal corresponding to incident light, and an OB (optical black) area (also referred to as a light shielding area) 123 that is always shielded. Including. Similarly, the light-shielded image 131 includes an effective area 132 and an OB area 133. In addition, since the plurality of light-shielded images 131 have different exposure times, the luminance values indicating the dark current amount (black level) are different.

Next, the imaging apparatus 100 converts, from the plurality of light-shielded images 131, the light-shielded image 131 in which the pixel value (luminance value) of the OB area 123 included in the main image 121 is close to the pixel value of the OB area 133, and the correction image 141. (S104). That is, the imaging apparatus 100 has a light-shielded image in which the difference between the pixel value of the light-shielded image 131 and the pixel value of the OB area 123 included in the main image 121 is less than a predetermined threshold among the plurality of light-shielded images 131. 131 is selected. For example, the imaging apparatus 100 selects the light-shielded image 131 having the smallest difference.

Further, this difference is, for example, a difference between an average value of a plurality of pixel values in the OB area 123 and an average value of a plurality of pixel values in the OB area 133. Note that a maximum value, a minimum value, or a median value may be used instead of the average value. The region used for comparison may be the entire OB region, a part of the OB region may be used, or a specific pixel included in the OB region may be used. In addition, it is preferable that the area | region used for a comparison is the same area | region.

Next, as illustrated in FIG. 9, the imaging apparatus 100 generates a corrected image 142 by subtracting the correction image 141 from the main image 121 (S105). Specifically, the pixel value of the pixel at the same position in the correction image 141 is subtracted from the pixel value of each pixel of the main image 121. Thereby, the influence of the dark current at the time of long exposure is reduced.

Also, during long-second exposure, the environment (for example, temperature) may change between the main exposure and the light-shielding exposure. Thereby, even when the exposure times of the main exposure and the light-shielding exposure are the same, the detected dark current amount may be different. On the other hand, as in the present embodiment, by selecting, as the correction image 141, a light-shielded image 131 having a pixel value in the OB area that is close to the light-shielded image 131 having different exposure times obtained by nondestructive readout. It is possible to suppress a difference in the amount of dark current between the main exposure and the light-shielding exposure.

Although FIG. 6 shows an example in which the non-destructive read cycle T4 is constant, it may not be constant. For example, the non-destructive readout interval at the time when the light shielding exposure time approaches the exposure time T1 of the main exposure may be shortened.

In FIG. 6, nondestructive reading is performed after a predetermined time has elapsed, but nondestructive reading may be performed periodically from the start of light-shielding exposure.

In FIG. 6, all of the plurality of light-shielded images 131 are obtained by non-destructive reading, but the last one reading may be destructive reading.

As described above, the imaging apparatus 100 according to the present embodiment includes the imaging element 101 capable of nondestructive reading, the imaging system 106 that collects light on the imaging element 101, and the light shielding that blocks the light of the imaging system 106. And a correction unit 105 that generates a corrected image 142 by subtracting the correction image 141 from the main image 121 obtained by the image sensor 101. The correction unit 105 obtains a plurality of light-shielded images 131 obtained by the image sensor 101 by one exposure in a light-shielded state, each having a different exposure time by using nondestructive reading, and obtains at least one of the plurality of light-shielded images 131. The correction image 141 is generated using the correction image 141.

This makes it possible to reduce the difference in dark current amount between the main exposure and the light-shielding exposure, which is caused by a temperature change or the like. Therefore, since the influence of dark current can be reduced, the image quality of the corrected image 142 can be improved.

Note that the function of shielding the light of the imaging system 106 is not limited to a method using a mechanical shutter, and may be a method using another mechanism such as electronic ND control. That is, the light shielding unit that shields the light of the imaging system 106 is not limited to the light shielding unit 107 (mechanical shutter or the like) illustrated in FIG. 1, and may be a mechanism for performing electronic ND control or the like.

The correction unit 105 also includes a light-shielded image 131 in which the difference between the pixel value of the light-shielded image 131 and the pixel value of the light-shielded region (OB region 123) included in the main image 121 is less than a threshold value. From this, a correction image 141 is generated. As a result, the correction image 141 can be generated using the light-shielded image 131 that has a small difference in dark current amount from the main image 121, so that the difference in dark current amount between the main image 121 and the correction image 141 can be reduced.

Further, the correction unit 105 calculates the pixel value of the light shielding area (OB area 133) of the light shielding image 131 and the pixel value of the light shielding area (OB area 123) included in the main image 121 among the plurality of light shielding images 131. A correction image 141 is generated from the light-shielded image whose difference is less than the threshold. That is, pixel values in the same region are compared. Thereby, the light-shielding image 131 with a similar dark current amount can be selected with high accuracy.

(Embodiment 2)
In the present embodiment, a modification of the first embodiment will be described. In the following description, differences from the previous embodiment will be mainly described, and redundant description will be omitted.

In the first embodiment, the example in which the exposure period T2 of the light shielding exposure and the number of the light shielding images 131 to be read nondestructively are set in advance has been described. In the present embodiment, the dark current amount of the light-shielded image 131 is dynamically determined, and the light-shielding exposure ends at the timing when the light-shielded image 131 having a dark current amount similar to the main image 121 is obtained. Thereby, compared with Embodiment 1, it can suppress that unnecessary nondestructive reading is performed.

FIG. 10 is a flowchart showing an operation flow of the imaging apparatus 100 according to the present embodiment. FIG. 11 is a diagram for explaining this operation. First, the imaging apparatus 100 captures the main image 121 as in the first embodiment, and starts light-shielding exposure at time t2 (S112).

Next, the imaging apparatus 100 performs nondestructive readout during the light-shielding exposure period (S113). Next, the imaging apparatus 100 determines whether the pixel value of the OB area 133 of the light-shielded image 131 obtained by nondestructive reading is close to the pixel value of the OB area 123 of the main image 121 (S114). Specifically, the imaging apparatus 100 determines whether the difference between the pixel value of the OB area 133 of the light-shielded image 131 and the pixel value of the OB area 123 of the main image 121 is less than a predetermined threshold value.

If the difference is not less than the threshold (No in S114), nondestructive reading is performed again (S113), and the same determination process is performed again (S114).

On the other hand, when the difference is less than the threshold (Yes in S114), the imaging apparatus 100 ends the light-shielding exposure (S115), and finally selects the light-shielded image 131 read by nondestructive readout as the correction image 141. (S116). For example, in the example illustrated in FIG. 11, at time t3, the difference is determined to be less than the threshold value, and the light-shielded image 131 is selected as the correction image 141.

Next, the imaging apparatus 100 generates a corrected image 142 by subtracting the correction image 141 from the main image 121 (S117).

As described above, the correction unit 105 repeats nondestructive reading until the difference between the pixel value of the light-shielded image 131 and the pixel value of the OB area 123 included in the main image 121 is less than the threshold, and the difference is less than the threshold. The shaded image 131 that has become is selected as the correction image 141.

Thereby, it is possible to suppress unnecessary nondestructive reading from being performed as compared with the first embodiment.

Note that the imaging apparatus 100 may perform destructive reading when the difference is less than the threshold, and use the obtained image as the correction image 141. FIG. 12 is a flowchart showing the operation of the imaging apparatus 100 in this case. FIG. 13 is a diagram for explaining this operation.

The process shown in FIG. 12 includes step S116A instead of step S116 with respect to the process shown in FIG. That is, when the difference is less than the threshold (Yes in S114), the imaging apparatus 100 ends the light-shielding exposure (S115), and acquires the correction image 141 by destructive reading (S116A).

For example, in the example shown in FIG. 13, at time t3, the difference is determined to be less than the threshold value. Thereafter, the imaging apparatus 100 acquires the correction image 141 by destructive reading. In FIG. 13, destructive readout is performed immediately after the determination, but may not be immediately after.

As described above, the correction unit 105 repeats nondestructive reading until the difference between the pixel value of the light-shielded image 131 and the pixel value of the OB area 123 included in the main image 121 is less than the threshold, and the difference is less than the threshold. In this case, a light-shielded image is acquired from the image sensor 101 by destructive readout, and the light-shielded image acquired by the destructive readout is selected as the correction image 141.

Here, in general, in non-destructive reading, some processing such as noise removal processing performed at the time of destructive reading is not performed. That is, an image obtained by destructive readout has higher image quality than an image obtained by nondestructive readout. Therefore, by using the image obtained by nondestructive readout for the determination process and using the image obtained by destructive readout as the correction image 141, it is possible to obtain a correction image 141 that shows the dark current amount more accurately. . Thereby, the image quality of the corrected image 142 can also be improved.

(Embodiment 3)
In the present embodiment, modified examples of the first and second embodiments will be described. In Embodiments 1 and 2, the example in which one light-shielded image 131 obtained by nondestructive readout or destructive readout is used as it is as the correction image 141 has been described. In this embodiment, an example in which a correction image 141 is generated using a plurality of shaded images 131 will be described.

FIG. 14 is a flowchart showing the operation of the modification of the first embodiment. The process shown in FIG. 14 includes step S104A instead of step S104 with respect to the process shown in FIG. FIG. 15 is a diagram for explaining this operation.

In step S <b> 104 </ b> A, the imaging apparatus 100 uses a plurality of light-shielded images 131 obtained by nondestructive readout to have a plurality of light-shielded images 131 in which the pixel value of the OB area 123 included in the main image 121 is close to the pixel value of the OB area 133. Is used to generate the correction image 141 (S104A).

For example, the imaging apparatus 100 includes a plurality of shaded images 131 in which a difference between a pixel value of the shaded image 131 and a pixel value of the OB area 123 included in the main image 121 is less than a predetermined threshold. A correction image 141 is generated using the light-shielded image 131. For example, the correction unit 105 generates the correction image 141 by averaging the plurality of light shielding images 131 whose difference is less than the threshold among the plurality of light shielding images 131.

For example, in the example shown in FIG. 15, it is determined that the difference is less than the threshold for the light-shielded image 131 read at times t3 and t4. Then, a correction image 141 is generated using the two light-shielded images 131.

Thus, by performing the averaging, for example, random noise generated in the signal readout path can be reduced. Note that the method of reducing random noise using a plurality of images is not limited to the averaging. For example, the pixel value of a pixel in which random noise is generated is a value that is distant from the pixel value of a pixel at the same position in another plurality of images. Therefore, the imaging apparatus 100 determines whether or not random noise is generated in each pixel of each image based on the variation in the pixel value of each pixel between images, and a pixel in which random noise is not generated. May be combined to generate the correction image 141. Alternatively, the imaging apparatus 100 may generate the correction image 141 by adding and averaging a plurality of light-shielded images 131 excluding pixels where random noise is generated.

As in the modification of the first embodiment, the plurality of light-shielded images 131 may include images that have been read out in a destructive manner.

Next, a case where a similar modification is applied to the second embodiment will be described. FIG. 16 is a flowchart showing the operation of the imaging apparatus 100 in this case. FIG. 17 is a diagram for explaining this operation.

The process shown in FIG. 16 includes steps S116B and S116C instead of step S116A with respect to the process shown in FIG.

When the difference is less than the threshold value (Yes in S114), the imaging apparatus 100 ends the light-shielding exposure (S115), and after performing nondestructive reading continuously, performs destructive reading, thereby The shaded image 131 is acquired (S116B). Next, the imaging apparatus 100 generates the correction image 141 using the plurality of light-shielded images 131 obtained in step S116B. The method for generating the correction image 141 is the same as that in step S104A, for example.

Further, as shown in FIG. 15, the non-destructive read interval T5 after the above difference is determined to be less than the threshold (after time t3) is shorter than the previous non-destructive read interval T4. That is, the correction unit 105 repeats nondestructive reading at the first interval T4 until the difference becomes less than the threshold, and when the difference becomes less than the threshold, the nondestructive reading is performed at the second interval T5 shorter than the first interval. The correction image 141 may be generated by repeating the above and averaging the plurality of shaded images 131 acquired by destructive readout at the second interval T5.

As a result, the correction image 141 can be generated using a plurality of light-shielded images 131 with a small difference in dark current amount from the main image 121, so that the difference in dark current amount between the main image 121 and the correction image 141 can be reduced. .

In the example shown in FIG. 17, destructive reading is performed at the end, but it may not be performed. In the example shown in FIG. 17, continuous nondestructive reading is performed after the exposure is completed, but nondestructive reading may be performed during the exposure.

An imaging apparatus 100 according to an aspect of the present disclosure includes an imaging element 101 capable of nondestructive readout, an imaging system 106 that collects light on the imaging element 101, a light shielding unit 107 that shields light from the imaging system 106, A correction unit 105 that generates a post-correction image 142 by subtracting the correction image 141 from the main image 121 obtained by the image pickup device 101. A plurality of shaded images 131 obtained with different exposure times are obtained using nondestructive readout, and a correction image 141 is generated using at least one of the plurality of shaded images 131.

According to this, it is possible to reduce a difference in dark current amount between the main exposure and the light-shielding exposure, which is caused by a temperature change or the like. Therefore, the influence of the dark current amount can be reduced, and the image quality of the corrected image 142 can be improved.

For example, the correction unit 105 corrects the correction image 141 from the light-shielded image 131 in which the difference between the pixel value of the light-shielded image 131 and the pixel value of the light-shielded area included in the main image 121 is less than the threshold among the plurality of light-shielded images 131. May be generated.

According to this, since the correction image 141 can be generated using the light-shielded image 131 with a small difference in dark current amount from the main image 121, the difference in dark current amount between the main image 121 and the correction image 141 can be reduced.

For example, the correction unit 105 may repeat non-destructive reading until the difference is less than the threshold, and may select the light-shielded image 131 in which the difference is less than the threshold as the correction image 141.

According to this, it is possible to suppress unnecessary nondestructive reading. Therefore, it is possible to suppress missing a photo opportunity when shooting continuously.

For example, the correction unit 105 repeats nondestructive reading until the difference between the pixel value of the read light-shielding image 131 and the pixel value of the light-shielding area included in the main image 121 is less than the threshold, and the difference is less than the threshold. In such a case, the shaded image 131 may be acquired from the image sensor 101 by destructive readout, and the shaded image 131 obtained by destructive readout may be selected as the correction image 141.

According to this, it is possible to obtain the correction image 141 that indicates the dark current amount more accurately, so that the image quality of the post-correction image 142 can be improved.

For example, the correction unit 105 may generate the correction image 141 by averaging the plurality of light shielding images 131 whose difference is less than the threshold among the plurality of light shielding images 131.

According to this, it is possible to reduce, for example, random noise generated in the signal readout path or the like.

For example, the correction unit 105 repeats nondestructive reading at a first interval until the difference becomes less than a threshold, and when the difference becomes less than the threshold, repeats nondestructive reading at a second interval shorter than the first interval. The correction image 141 may be generated by averaging the plurality of light-shielded images 131 obtained by nondestructive reading at the second interval.

According to this, since the correction image 141 can be generated using a plurality of light-shielded images 131 with a small difference in dark current amount from the main image 121, the difference in dark current amount between the main image 121 and the correction image 141 is reduced. Can be reduced.

For example, the correction unit 105 corrects a light-shielded image 131 in which the difference between the pixel value of the light-shielded area of the light-shielded image 131 and the pixel value of the light-shielded area included in the main image 121 is less than the threshold among the plurality of light-shielded images 131. A work image 141 may be generated.

According to this, the light-shielded image 131 having a similar dark current amount can thereby be selected with high accuracy.

For example, the image sensor 101 may be an organic sensor.

A control method according to an aspect of the present disclosure includes an imaging element 101 capable of nondestructive reading, an imaging system 106 that collects light on the imaging element 101, and a light shielding unit 107 that shields light from the imaging system 106. The control method of the imaging apparatus 100 includes a correction step of generating a corrected image 142 by subtracting the correction image 141 from the main image 121 obtained by the imaging element 101. In the correction step, the light shielding state is performed once. A plurality of light-shielded images 131 obtained by the image sensor 101 by the above exposure and having different exposure times are acquired using nondestructive readout, and a correction image 141 is generated using at least one of the plurality of light-shielded images 131.

Note that these comprehensive or specific modes may be realized by a system, a method, an integrated circuit, a computer program, or a recording medium such as a computer-readable CD-ROM, and the system, method, integrated circuit, and computer program. Also, any combination of recording media may be realized.

The imaging device according to the embodiment of the present disclosure has been described above, but the present disclosure is not limited to this embodiment.

For example, each processing unit included in the imaging apparatus according to the above embodiment is typically realized as an LSI that is an integrated circuit. These may be individually made into one chip, or may be made into one chip so as to include a part or all of them.

Further, the integration of circuits is not limited to LSI, and may be realized by a dedicated circuit or a general-purpose processor. An FPGA (Field Programmable Gate Array) that can be programmed after manufacturing the LSI or a reconfigurable processor that can reconfigure the connection and setting of circuit cells inside the LSI may be used.

Further, in each of the above embodiments, each component may be configured by dedicated hardware or may be realized by executing a software program suitable for each component. Each component may be realized by a program execution unit such as a CPU or a processor reading and executing a software program recorded on a recording medium such as a hard disk or a semiconductor memory.

Also, the present disclosure may be realized as a control method executed by the imaging apparatus.

The circuit configuration shown in the circuit diagram is an example, and the present disclosure is not limited to the circuit configuration. That is, similar to the circuit configuration described above, a circuit that can realize the characteristic function of the present disclosure is also included in the present disclosure. Moreover, all the numbers used above are illustrated for specifically explaining the present disclosure, and the present disclosure is not limited to the illustrated numbers.

In addition, division of functional blocks in the block diagram is an example, and a plurality of functional blocks can be realized as one functional block, a single functional block can be divided into a plurality of functions, or some functions can be transferred to other functional blocks. May be. In addition, functions of a plurality of functional blocks having similar functions may be processed in parallel or time-division by a single hardware or software.

In addition, the order in which the steps in the flowchart are executed is for illustration in order to specifically describe the present disclosure, and may be in an order other than the above. Also, some of the above steps may be executed simultaneously (in parallel) with other steps.

As described above, the imaging device according to one or more aspects has been described based on the embodiment, but the present disclosure is not limited to this embodiment. Unless it deviates from the gist of the present disclosure, various modifications conceived by those skilled in the art have been made in this embodiment, and forms constructed by combining components in different embodiments are also within the scope of one or more aspects. May be included.

The present disclosure can be applied to an imaging apparatus such as a digital still camera or a digital video camera.

DESCRIPTION OF SYMBOLS 100 Image pick-up device 101 Image pick-up element 102 Control part 103 Display part 104 Storage part 105 Correction part 106 Imaging system 107 Light-shielding part 121 Main image 122,132

Effective area

123, 133 OB area 131 Light-shielded image 141 Image for correction 142 Image after correction 201 Pixel 202 vertical scanning unit 203 column signal processing unit 204 horizontal readout unit 205 reset control line 206 address control line 207 vertical signal line 208 horizontal output terminal 211 photoelectric conversion unit 212 charge storage unit 213 reset transistor 214 amplification transistor 215 selection transistor

Claims

An image sensor capable of non-destructive readout;
An imaging system for condensing light on the imaging device;
A light shielding part for shielding light of the imaging system;
A correction unit that generates a corrected image by subtracting a correction image from the main image obtained by the imaging element;
The correction unit is
A plurality of light-shielded images obtained by the image sensor by one exposure in a light-shielding state, each having a different exposure time, are acquired using nondestructive readout,
An imaging apparatus that generates the correction image using at least one of the plurality of light-shielded images.
The correction unit is
The imaging according to claim 1, wherein the correction image is generated from a light-shielded image in which a difference between a pixel value of the light-shielded image and a pixel value of a light-shielded area included in the main image is less than a threshold value among the plurality of light-shielded images. apparatus.
The correction unit is
Repeat the non-destructive readout until the difference is less than the threshold,
The imaging apparatus according to claim 2, wherein a light-shielded image in which the difference is less than the threshold is selected as the correction image.
The correction unit is
The non-destructive reading is repeated until the difference between the pixel value of the read light-shielded image and the pixel value of the light-shielded region included in the main image is less than a threshold value,
If the difference is less than the threshold, obtain a light-shielded image from the image sensor by destructive readout,
The imaging apparatus according to claim 1, wherein the shaded image acquired by the destructive readout is selected as the correction image.
The correction unit is
The imaging device according to claim 2, wherein among the plurality of light-shielded images, the correction image is generated by adding and averaging a plurality of light-shielded images having the difference less than the threshold value.
The correction unit is
Repeat the non-destructive readout at a first interval until the difference is less than the threshold,
If the difference is less than the threshold, repeat the non-destructive reading at a second interval shorter than the first interval,
The imaging apparatus according to claim 5, wherein the correction image is generated by averaging the plurality of light-shielded images acquired by the nondestructive reading at the second interval.
The correction unit is
The correction image is generated from the light-shielded image in which the difference between the pixel value of the light-shielded area of the light-shielded image and the pixel value of the light-shielded area included in the main image is less than the threshold among the plurality of light-shielded images. The imaging device according to claim 2.
The imaging apparatus according to any one of claims 1 to 7, wherein the imaging element is an organic sensor.
An imaging device control method comprising: an imaging device capable of nondestructive readout; an imaging system that collects light on the imaging device; and a light shielding unit that shields light from the imaging system,
Including a correction step of generating a corrected image by subtracting the correction image from the main image obtained by the imaging element;
In the correction step,
A plurality of light-shielded images obtained by the image sensor by one exposure in a light-shielding state, each having a different exposure time, are acquired using nondestructive readout,
A control method for generating the correction image using at least one of the plurality of light-shielded images.