JP2008277879A - Imaging device, imaging method, and integrated circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To widen the dynamic range that an imaging device needs to have by eliminating an error due to different processing for correction etc., without lowering resolution. <P>SOLUTION: An L/S separation unit 3 separates a video signal that an imaging unit 1 captures in a different charge accumulation time for each frame into a long signal and a short signal. An interpolation unit 7 converts a corrected short signal, generated by a multiplication unit 6 by adjusting the gain of the short signal, into an interpolated long signal. A selection unit 8 selects the long signal and interpolated long signal to obtain a corrected long signal. An L/S synthesis unit 9 obtains a video signal by synthesizing the corrected short signal with corrected long signal. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image pickup apparatus, an image pickup method, and an integrated circuit capable of dealing with a moving image and expanding a dynamic range without degradation in resolution by a combination of an image pickup element driving method and signal processing.

In recent years, imaging apparatuses have been used for various purposes, and methods for increasing the SN ratio, increasing the resolution, and increasing the dynamic range of captured images acquired by the imaging apparatus have been proposed depending on the applications used. ing.
A conventional imaging apparatus having a function of expanding the dynamic range will be described below.
2. Description of the Related Art Conventionally, an image pickup apparatus for expanding a dynamic range is known as disclosed in Japanese Patent Application Laid-Open No. 9-116815. FIG. 4 shows a schematic configuration diagram of an imaging element unit 900 (using a CCD) of this conventional imaging apparatus. The image sensor unit 900 includes a high-sensitivity pixel 21 arranged in the vertical direction, a low-sensitivity pixel 22 arranged in the vertical direction, a vertical CCD 23 that transfers charges vertically, a horizontal CCD 24 that transfers charges horizontally, The limiter 25 clips a predetermined charge amount or more, and the charge detection unit 26 having a floating diffusion amplifier configuration. In the image sensor unit 900, the high-sensitivity pixels 21 and the low-sensitivity pixels 22 are alternately arranged in the horizontal direction (the horizontal direction in FIG. 4). That is, the high sensitivity pixels 21 and the low sensitivity pixels 22 are alternately arranged so that the columns of the high sensitivity pixels 21 and the columns of the low sensitivity pixels 22 form a stripe.

Next, the operation of the conventional imaging apparatus having the imaging element unit 900 will be described. First, the charge obtained by photoelectric conversion by the high sensitivity pixel 21 and the charge obtained by photoelectric conversion by the low sensitivity pixel 22 are obtained. All pixels are transferred to the vertical CCD 23 in synchronization with the vertical synchronization signal. The charges transferred to the vertical CCD 23 are further transferred to the horizontal CCD 24 in synchronization with the horizontal synchronization signal. The charge transferred to the horizontal CCD 24 is clipped by the limiter 25 before being transferred to the charge detection unit 26 if the charge is a predetermined level or more. The charge transferred to the horizontal CCD 24 is clipped by the limiter 25 and then transferred to the charge detection unit 26. At this time, the pulse applied to the reset gate RG is generated by adding the charge from the adjacent high-sensitivity pixel and the charge from the low-sensitivity pixel by driving at half the frequency of the drive pulse of the horizontal CCD 24. Output from the image sensor unit 900.

  As shown in FIG. 5, the signal amount (charge amount) obtained (output) from the high-sensitivity pixel 21 and the low-sensitivity pixel 22 increases in direct proportion as the amount of light increases, but is set by the limiter 25. When the predetermined amount TH1 is exceeded, the signal amount becomes a constant value D1, and does not increase any further. On the other hand, in the low-sensitivity pixel 22, even if the light amount exceeds the predetermined amount TH1, the signal amount (charge amount) output from the low-sensitivity pixel 22 does not exceed the fixed value D1. Therefore, the signal amount (charge amount) output from the low-sensitivity pixel 22 increases in proportion to the light amount even if the light amount increases to a predetermined amount TH1 or more. The charge detection unit 26 adds and mixes the two pixel signals of the signal based on the charge acquired by the high sensitivity pixel 21 and the signal based on the charge acquired by the low sensitivity pixel 22. The signal mixed by the charge detection unit 26 (the signal after mixing) has a characteristic indicated by L1 in FIG. As can be seen from the light quantity-signal quantity characteristic shown in L1 of FIG. 5, the mixed signal is obtained as a signal having a wide dynamic range without saturation of the output signal quantity even when the light quantity is large. .

FIG. 6 is a timing chart for explaining the operation of the image pickup apparatus disclosed in Japanese Patent Laid-Open No. 9-200261.
FIG. 6 shows drive pulses for the image pickup device (image pickup device using CCD) of the image pickup apparatus.
In this image pickup apparatus, the image pickup device is operated with the readout gate pulse VG, the vertical register transfer pulse VS, and the horizontal register transfer pulse VH being doubled with respect to the vertical pulse VD.
As shown in FIG. 6, in this imaging apparatus, the frame is divided into two front and rear, the signal is taken out with a long charge accumulation time (corresponding to the normal accumulation time in FIG. 6) in the first half frame, and the short charge is taken in the second half frame. A signal is extracted at the accumulation time (corresponding to the shutter accumulation time in FIG. 6), and then both signals are combined. According to this method, when the amount of light increases in the first half of the frame, the output of the signal due to the charge acquired by the image sensor is saturated, but in the second half, it is not saturated, so there is no saturation by combining these two types of signals. A signal can be obtained. Therefore, by using this method, the dynamic range of the imaging apparatus can be expanded.
JP-A-9-116815 Japanese Patent Laid-Open No. 9-200261

However, the imaging apparatus disclosed in Japanese Patent Laid-Open No. 9-116815 has a problem that the resolution deteriorates because two pixels are added to form a signal of one pixel.
In the imaging device disclosed in Japanese Patent Laid-Open No. 9-200261, an image signal for one screen is acquired twice in one frame period while changing the charge accumulation time, and the two acquired image signals are synthesized. Therefore, it is difficult to increase the speed. That is, in this imaging apparatus, only one screen image signal can be acquired within one frame period, and N screen image signals (N is a natural number of N> 1) are acquired within one frame period. It is difficult to realize such processing. In addition, in this imaging apparatus, when a moving moving image is processed within one frame period, the timings of two charge accumulation times for accumulating charges in the imaging element are different, so that the two acquired image signals are misaligned. When an image formed by combining the two acquired image signals is displayed on a display device, there is a problem that an image (video) on the display screen is displaced.

  The present invention solves the above-described problems, and can output a video signal with no deterioration in resolution, and it can be applied to a moving image that changes drastically within a predetermined period (for example, a frame period or a field period). However, an object of the present invention is to provide an imaging device, an imaging method, and an integrated circuit that can suppress the occurrence of video (image) blurring.

  A first invention includes an imaging unit, a charge accumulation time setting unit, a switching unit, a drive unit, an L / S separation unit, a saturation detection unit, a correction value calculation unit, a multiplication unit, an interpolation unit, , An imaging device including a selection unit and an L / S synthesis unit. The imaging unit is an imaging device including a plurality of pixels that can set different charge accumulation times for each pixel, and is not included in the first pixel group including the pixels and the first pixel group. The image sensor includes a second pixel group including pixels, and acquires a video signal by converting light from a subject into an electrical signal. The charge accumulation time setting unit sets a first charge accumulation time and a second charge accumulation time that is longer than the first charge accumulation time as the charge accumulation times of the first pixel group and the second pixel group. The switching unit switches the first charge accumulation time and the second charge accumulation time for each unit image acquisition period. The drive unit drives the imaging unit based on the first charge accumulation time and the second charge accumulation time that are switched by the switching unit for each unit image acquisition period. The L / S separation unit outputs a video signal output from the imaging unit to a short signal that is a video signal acquired by the first charge accumulation time and a long signal that is a video signal acquired by the second charge accumulation time. To separate. The saturation detector detects the signal level of the long signal. The correction value calculation unit calculates a correction value for correcting the signal level of the short signal to the signal level of the long signal based on the first charge accumulation time and the second charge accumulation time. The multiplication unit obtains a corrected short signal by multiplying the short signal by the correction value calculated by the correction value calculation unit. The interpolation unit interpolates the corrected short signal to obtain an interpolated long signal that is a signal having the same timing as the long signal. The selection unit selects the long signal when the saturation detection unit determines that the signal level of the long signal is equal to or lower than the predetermined value, and the selection unit determines that the signal level of the long signal exceeds the predetermined value. In such a case, an interpolated long signal is selected, and the selected signal is acquired as a modified long signal. The L / S synthesis unit generates an output video signal by sequentially switching the modified long signal output from the selection unit and the modified short signal output from the multiplication unit.

In this imaging apparatus, a long signal and a short signal are acquired by an L / S separation unit from a video signal output from an imaging unit having an imaging element including a first pixel group and a second pixel group. Further, the saturation detection unit detects whether or not the long signal is saturated. For the portion where the long signal is saturated, the short signal is replaced with an interpolated long signal interpolated to the signal level of the long signal, and the corrected long The output video signal is generated by sequentially switching the modified long signal and the modified short signal output from the multiplying unit by the L / S synthesis unit. Then, the charge storage time of the first pixel group and the charge storage time of the second pixel group are replaced with the first charge storage time and the second charge storage time for each unit image acquisition time by the switching unit and the drive unit. Thus, the imaging unit 1 is driven.
In this imaging apparatus, a long signal with a long S / N ratio is obtained for a portion where the signal level of the long signal is not saturated, and a charge accumulation time for a portion where the signal level of the long signal is saturated. Since the output video signal is generated by using the short short signal, it is possible to output the video signal without any degradation in resolution and to change drastically within a predetermined period (for example, a frame period or a field period). The occurrence of video (image) blurring can also be suppressed for moving images.

Furthermore, in this imaging device, the video signal acquisition process at the pixels of the imaging unit is alternated every unit image acquisition time, so that a fixed pattern (acquired at the pixels of the imaging unit) that occurs when the video signal is displayed on the display device. (Fixed pattern noise caused by an error in the video signal) can be removed.
Here, “unit image acquisition time” refers to a time for forming one image when a video signal is displayed on a display device. For example, one frame period in an NTSC television signal ( This corresponds to 1/30 [s] in the case of the interlace method and 1 field period (1/60 [s] in the case of the interlace method).

The second invention is the first invention, wherein the unit image acquisition period is one frame period.
Here, “one frame period” refers to a time for forming one image when displaying a video signal of a predetermined format on a display screen. For example, an interlace NTSC television signal is used. 1/30 [s], and in the case of a non-interlace (progress) NTSC television signal, 1/60 [s] and a high-resolution video signal (video signal such as HDTV)) In the case of HDTV signal in 1080p30 format, 1/30 [s], and in the case of 720p60 format HDTV signal, 1/60 [s].
3rd invention is 1st or 2nd invention, Comprising: An image pick-up element is comprised from the pixel of several rows and several columns, a 1st pixel group is comprised from the pixel of odd-numbered columns, and 2nd pixel group Is composed of pixels in even columns.
Thereby, the pixels in the odd columns can be used as the first pixel group, and the pixels in the even columns can be used as the second pixel group, so that the switching unit and the drive unit can be configured easily.
According to a fourth aspect of the present invention, the image sensor is composed of pixels in a plurality of rows and columns, the first pixel group is composed of pixels in even columns, and the second pixel group is composed of pixels in odd columns.
Accordingly, even-numbered columns of pixels can be used as the first pixel group, and odd-numbered columns of pixels can be used as the second pixel group, so that the switching unit and the driving unit can be configured easily.

According to a fifth aspect of the invention, the image sensor is composed of pixels in a plurality of rows and columns, the first pixel group is composed of pixels in odd rows, and the second pixel group is composed of pixels in even rows.
Thereby, the pixels in the odd rows can be used as the first pixel group, and the pixels in the even rows can be used as the second pixel group, so that the switching unit and the driving unit can be configured easily.
According to a sixth aspect of the invention, the image sensor is composed of pixels in a plurality of rows and columns, the first pixel group is composed of pixels in even rows, and the second pixel group is composed of pixels in odd rows.
Accordingly, even-numbered rows of pixels can be used as the first pixel group, and odd-numbered rows of pixels can be used as the second pixel group, so that the switching unit and the drive unit can be configured easily.
In the seventh invention, the image pickup device is a CMOS image sensor.
Thereby, an imaging apparatus is realizable by using a CMOS type image sensor as an image pick-up element of an image pick-up part.

An eighth invention is an imaging device including a plurality of pixels that can set different charge accumulation times for each pixel, and is included in the first pixel group including the pixels and the first pixel group. This is an imaging method used in an imaging apparatus having an imaging device including a second pixel group composed of pixels that are not capable of acquiring a video signal by converting light from a subject into an electrical signal. A charge accumulation time setting step, a switching step, a driving step, an L / S separation step, a saturation detection step, a correction value calculation step, a multiplication step, an interpolation step, a selection step, and an L / S. And a synthesis step. In the charge accumulation time setting step, the first charge accumulation time and the second charge accumulation time that is longer than the first charge accumulation time are set as the charge accumulation times of the first pixel group and the second pixel group. In the switching step, the first charge accumulation time and the second charge accumulation time are switched for each unit image acquisition period. In the driving step, the imaging unit is driven based on the first charge accumulation time and the second charge accumulation time switched for each unit image acquisition period in the switching step. In the L / S separation step, the video signal output in the imaging step is divided into a short signal that is a video signal acquired by the first charge accumulation time, and a long signal that is a video signal acquired by the second charge accumulation time. To separate. In the saturation detection step, the signal level of the long signal is detected. In the correction value calculation step, a correction value for correcting the signal level of the short signal to the signal level of the long signal is calculated based on the first charge accumulation time and the second charge accumulation time. In the multiplication step, the corrected short signal is obtained by multiplying the short signal by the correction value calculated in the correction value calculating step. In the interpolation step, the corrected short signal is interpolated to obtain an interpolated long signal that is a signal having the same timing as the long signal. In the selection step, when it is determined by the saturation detection step that the signal level of the long signal is equal to or lower than the predetermined value, the long signal is selected, and the saturation detection unit determines that the signal level of the long signal exceeds the predetermined value. In such a case, an interpolated long signal is selected, and the selected signal is acquired as a modified long signal. In the L / S synthesis step, an output video signal is generated by sequentially switching between the modified long signal output from the selection step and the modified short signal output from the multiplier.
Thereby, it is possible to realize an imaging method having the same effect as that of the first invention.

A ninth invention is an imaging device including a plurality of pixels capable of setting different charge accumulation times for each pixel, and is included in the first pixel group including the pixels and the first pixel group. An integrated circuit used together with an image pickup unit having an image pickup device including a second pixel group composed of non-pixels and acquiring a video signal by converting light from a subject into an electric signal, A time setting unit, a switching unit, a drive unit, an L / S separation unit, a saturation detection unit, a correction value calculation unit, a multiplication unit, an interpolation unit, a selection unit, an L / S synthesis unit, Is an integrated circuit. The charge accumulation time setting unit sets a first charge accumulation time and a second charge accumulation time that is longer than the first charge accumulation time as the charge accumulation times of the first pixel group and the second pixel group. The switching unit switches the first charge accumulation time and the second charge accumulation time for each unit image acquisition period. The drive unit drives the imaging unit based on the first charge accumulation time and the second charge accumulation time that are switched by the switching unit for each unit image acquisition period. The L / S separation unit outputs a video signal output from the imaging unit to a short signal that is a video signal acquired by the first charge accumulation time and a long signal that is a video signal acquired by the second charge accumulation time. To separate. The saturation detector detects the signal level of the long signal. The correction value calculation unit calculates a correction value for correcting the signal level of the short signal to the signal level of the long signal based on the first charge accumulation time and the second charge accumulation time. The multiplication unit obtains a corrected short signal by multiplying the short signal by the correction value calculated by the correction value calculation unit. The interpolation unit 7 interpolates the corrected short signal and obtains an interpolated long signal that is a signal having the same timing as the long signal. The selection unit selects the long signal when the saturation detection unit determines that the signal level of the long signal is equal to or lower than the predetermined value, and the selection unit determines that the signal level of the long signal exceeds the predetermined value. In such a case, an interpolated long signal is selected, and the selected signal is acquired as a modified long signal. The L / S synthesis unit generates an output video signal by sequentially switching the modified long signal output from the selection unit and the modified short signal output from the multiplication unit.
By using this integrated circuit together with the imaging unit, an integrated circuit that exhibits the same effect as that of the first invention can be realized.

A tenth aspect of the invention includes an imaging unit, a charge accumulation time setting unit, a switching unit, a drive unit, an L / S separation unit, a saturation detection unit, a correction value calculation unit, a multiplication unit, an interpolation unit, , An integrated circuit including a selection unit and an L / S synthesis unit. The imaging unit is an imaging device including a plurality of pixels that can set different charge accumulation times for each pixel, and is not included in the first pixel group including the pixels and the first pixel group. The image sensor includes a second pixel group including pixels, and acquires a video signal by converting light from a subject into an electrical signal. The charge accumulation time setting unit sets a first charge accumulation time and a second charge accumulation time that is longer than the first charge accumulation time as the charge accumulation times of the first pixel group and the second pixel group. The switching unit switches the first charge accumulation time and the second charge accumulation time for each unit image acquisition period. The drive unit drives the imaging unit based on the first charge accumulation time and the second charge accumulation time that are switched by the switching unit for each unit image acquisition period. The L / S separation unit outputs a video signal output from the imaging unit to a short signal that is a video signal acquired by the first charge accumulation time and a long signal that is a video signal acquired by the second charge accumulation time. To separate. The saturation detection unit detects a signal level of the long signal. The correction value calculation unit calculates a correction value for correcting the signal level of the short signal to the signal level of the long signal based on the first charge accumulation time and the second charge accumulation time. The multiplication unit obtains a corrected short signal by multiplying the short signal by the correction value calculated by the correction value calculation unit. The interpolation unit interpolates the corrected short signal to obtain an interpolated long signal that is a signal having the same timing as the long signal. The selection unit selects the long signal when the saturation detection unit determines that the signal level of the long signal is equal to or lower than the predetermined value, and the selection unit determines that the signal level of the long signal exceeds the predetermined value. In such a case, an interpolated long signal is selected, and the selected signal is acquired as a modified long signal. The L / S synthesis unit generates an output video signal by sequentially switching the modified long signal output from the selection unit and the modified short signal output from the multiplication unit.
Thus, an integrated circuit that exhibits the same effect as that of the first invention can be realized.

According to the present invention, a video (image) can be output even for a moving image that can output a video signal with no degradation in resolution and changes drastically within a predetermined period (for example, a frame period or a field period). An imaging device, an imaging method, and an integrated circuit that can suppress the occurrence of blurring can be realized.
Furthermore, in the present invention, since the video signal acquisition process at the pixels of the imaging unit is alternated for each frame, a fixed pattern (a video signal acquired at the pixels of the imaging unit) that is generated when the video signal is displayed on the display device. (Fixed pattern noise caused by error) can be removed.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
<1: Configuration of imaging device>
FIG. 1 shows a configuration diagram of an imaging apparatus 100 according to the first embodiment of the present invention.
The imaging apparatus 100 includes an imaging unit 1, a driving unit 2 for driving the imaging unit 1, a switching unit 12 that changes a setting value related to driving of the imaging unit 1 of the driving unit 2 for each frame, and a charge accumulation time. An L / S separation unit 3 that separates video signals acquired by the imaging unit 1 according to the length, and a saturation detection unit 4 that detects whether or not the level of a long signal obtained from a pixel having a long charge accumulation time exceeds a predetermined level. A correction value calculation unit 5 that corrects a pixel output level that fluctuates depending on the charge accumulation time, a multiplication unit 6 that corrects a short signal to correct a signal drop due to the charge accumulation time, and obtain a corrected short signal; And an interpolation unit 7 for obtaining an interpolated long signal having the same timing as the midpoint of the corrected short signal, that is, the long signal, using the corrected short signal. Furthermore, the imaging apparatus 100 obtains a video signal by sequentially switching between a selection unit 8 that selects either a long signal or an interpolated long signal based on a detection result in the saturation detection unit 4, and a correction long signal and a correction short signal. An L / S synthesis unit 9; a process unit 10 for performing signal processing for the camera such as gamma correction and DTL (detail) addition for the video signal; a driving pulse signal for determining the synchronization signal of the camera and the driving timing of the imaging unit 1; And a timing generator unit 11 that generates setting values and the like related to driving of the imaging unit 1 for each frame.

The imaging unit 1 acquires light from the subject as an electrical signal by photoelectric conversion, and outputs the acquired electrical signal to the L / S separation unit.
FIG. 2 shows a configuration diagram of the imaging unit 1 (in the case of a CMOS image sensor), the driving unit 2 and the switching unit 12 of the imaging apparatus of the present invention. In FIG. 2, the imaging unit 1 includes 6 pixels horizontally and 4 pixels vertically, and each pixel 13 includes a photodiode. Needless to say, the number of pixels is for convenience of explanation and is not limited to this number of pixels.
As shown in FIG. 2, the imaging unit 1 includes a plurality of pixels 13 that are arranged vertically and horizontally, a switch transistor 17, and an output amplifier 18. The pixel 13 is an element that accumulates charges proportional to the amount of incident light and outputs an electrical signal corresponding to the accumulated charge amount. As the imaging unit 1, a CMOS type image sensor is preferably used.

  The driving unit 2 outputs a control signal (such as a camera synchronization signal or a driving pulse signal for determining the driving timing of the imaging unit 1) output from the timing generator unit 11 and input to the driving unit 2 via the switching unit 12. Based on this, the imaging unit 1 is driven. As shown in FIG. 2, the drive unit 2 includes a first vertical register / shutter 14, a second vertical register / shutter 15, and a horizontal register 16. The first vertical register shutter 14 is connected to the pixels 13 in the odd-numbered columns, selects a horizontal line address, operates the pixel 13 at the selected horizontal address for a specified time, and accumulates charges. (So-called electronic shutter function is realized). The second vertical register shutter 15 is connected to the even number of pixels 13 and selects a horizontal line address, operates the pixel 13 at the selected horizontal address for a specified time, and accumulates charges. (So-called electronic shutter function is realized). As the first vertical register / shutter 14 and the second vertical register / shutter 15, for example, a shift register circuit can be used. The horizontal register 16 is connected to the switch transistors 17 provided for the number of columns formed by the pixels 13 as shown in FIG. 2, and selects a vertical line address (performs horizontal scanning). The horizontal register 16 selects the vertical line address by turning on the switch transistor 17 corresponding to the vertical line address. The output amplifier 18 is connected to the switch transistor 17 as shown in FIG. When an electrical signal corresponding to the amount of charge accumulated in the pixel 13 at the address selected by the first vertical register / shutter 14, the second vertical register / shutter 15 and the horizontal register 16 is input to the output amplifier 18, an output is made. The amplifier 18 amplifies the input signal and outputs it to the L / S separation unit 3 via the output terminal 19.

Since the imaging unit 1 and the driving unit 2 configured in this manner can individually control the charge accumulation time of each pixel 13, the charge amount accumulation time when acquiring an image signal for one screen is easy. Can be adjusted. For example, it is possible to easily shorten the charge accumulation time of the pixels 13 arranged in the odd columns and lengthen the charge accumulation time of the pixels 13 arranged in the even columns.
Hereinafter, as an initial state, the charge accumulation time of the pixel 13 (hereinafter referred to as “first pixel group”) arranged at a predetermined position is shortened (hereinafter, this charge accumulation time is referred to as “short charge”). The charge accumulation time of the pixels 13 other than the first pixel group (hereinafter, these pixels are referred to as “second pixel group”) is lengthened (hereinafter, this charge accumulation time is referred to as “long charge accumulation”). The case will be described. For example, in the configuration shown in FIG. 2, pixels arranged in odd columns are pixels belonging to the first pixel group, and pixels arranged in even columns are pixels belonging to the second pixel group.

  The switching unit 12 includes the first vertical register so that the charge accumulation time of the pixels 13 belonging to the first pixel group is short and the charge accumulation time of the pixels 13 belonging to the second pixel group is long charge accumulation time. Set the setting values of the shutter 14, the second vertical register / shutter 15, and the horizontal register 16. Then, the switching unit 12 outputs the video signal of the initial state frame (current frame) from the imaging unit 1 and starts acquiring the video signal of the next frame by the imaging unit 1 (hereinafter referred to as “next frame acquisition start”). At this point, the charge accumulation time of each pixel 13 is changed. In other words, the switching unit 12 sets the charge accumulation time of the pixels 13 belonging to the first pixel group whose charge accumulation time is set to the short charge accumulation time in the previous frame at the start of the next frame acquisition to the long charge accumulation time. In addition, the charge accumulation time of the pixels 13 belonging to the second pixel group whose charge accumulation time is set to the long charge accumulation time in the previous frame is changed to the short charge accumulation time. For example, in the case of the configuration shown in FIG. 2, pixels arranged in even columns are pixels belonging to the first pixel group, and pixels arranged in odd columns are pixels belonging to the second pixel group.

The L / S separation unit 3 separates the signal output from the imaging unit 1 according to the length of the charge accumulation time of the pixel 13. When the output signal from the imaging unit 1 when the charge accumulation time of the pixel 13 is long is a long signal, and the output signal from the imaging unit 1 when the charge accumulation time of the pixel 13 is long is a short signal, the L / S separation unit 3 outputs the long signal to the saturation detection unit 4 and the selection unit 8, and outputs the short signal to the multiplication unit 6. Further, a control signal can be input to the L / S separator 3 from the timing generator unit 11, and the L / S separator 3 outputs a long signal and a short signal based on the control signal from the timing generator unit 11. To do.
The saturation detection unit 4 receives the long signal output from the L / S separation unit 3 and detects whether or not the level of the long signal obtained from the pixel 13 having a long charge accumulation time exceeds a predetermined level. The result is output to the selection unit 8.

The correction value calculation unit 5 calculates a correction value for correcting a pixel output level (an output level of an electric signal output from each pixel 13) that varies depending on the charge accumulation time. The correction value is calculated based on the charge accumulation time of the pixel 13 for generating the long signal and the charge accumulation time of the pixel 13 for generating the short signal. The correction value calculation unit 5 acquires information about the charge accumulation time of the pixel 13 for generating the long signal and the charge accumulation time of the pixel 13 for generating the short signal from the timing generator unit 11, and includes the information Based on this, a correction value is calculated, and the calculated correction value is output to the multiplication unit 6.
The multiplication unit 6 multiplies the correction value output from the correction value calculation unit 5 by the short signal output from the L / S separation unit 3 and interpolates the signal obtained by the multiplication as a modified short signal. To the unit 7 and the L / S synthesis unit 9.

The interpolation unit 7 generates an interpolation long signal having the same timing as the intermediate point of the corrected short signal, that is, the long signal, using the corrected short signal output from the multiplication unit 6, and outputs the generated interpolation long signal to the selection unit 8. To do. For example, the interpolation unit 7 performs an averaging process (arithmetic averaging, geometric averaging, LPF process) on the two modified short signals before and after and generates an interpolated long signal.
The selection unit 8 receives the detection result from the saturation detection unit 4, the long signal output from the L / S separation unit 3, and the interpolated long signal output from the interpolation unit 7, and receives a long signal from the saturation detection unit 4. Is determined to be equal to or lower than a predetermined level, the long signal is output as a modified long signal to the L / S synthesis unit 9, and when the saturation detection unit 4 determines that the long signal exceeds the predetermined level, interpolation is performed. The long signal is output as a modified long signal to the L / S synthesis unit 9.

The L / S combiner 9 receives the modified long signal output from the selector 8, the modified short signal output from the multiplier 6, and the control signal from the timing generator unit as inputs. Based on the control signal, the modified long signal and the modified short signal are sequentially switched and output to the process unit 10 as a video signal.
The process unit 10 performs camera signal processing such as gamma correction and DTL (detail) addition on the video signal output from the L / S synthesis unit 9.
The timing generator unit 11 generates a synchronization signal of the camera, a driving pulse signal that determines the driving timing of the imaging unit 1, and the like, and outputs them to the switching unit 12. In addition, the timing generator unit 11 outputs information about the frame (information about the frame of the video signal acquired by the imaging unit 1) to the switching unit 12. In addition, the timing generator unit 11 outputs a control signal for adjusting the timing of the output signal to the L / S separation unit 3 and the L / S synthesis unit 9. Further, the timing generator unit 11 outputs information regarding the charge accumulation time of the pixel 13 for generating the long signal and the charge accumulation time of the pixel 13 for generating the short signal to the correction value calculation unit 5. The function of the charge accumulation time setting unit is realized by the timing generator unit 11.

The switching unit 12 outputs a camera synchronization signal input from the timing generator unit 11, a driving pulse signal for determining the driving timing of the imaging unit 1, and the like to the imaging unit 1. The switching unit 12 determines whether the charge accumulation time of the pixel 13 belonging to the first pixel group and the charge accumulation time of the pixel 13 belonging to the second pixel group are based on the information about the frame input from the timing generator unit 11. For each frame, a drive pulse signal or the like is output to the drive unit 2 so that the short charge accumulation time and the long charge accumulation time are alternately obtained.
<2: Operation of Imaging Device>
The operation of the imaging apparatus 100 configured as described above will be described with reference to FIGS.
FIG. 3 is a timing chart showing signal waveforms at points (points a to g) of the imaging apparatus 100 shown in FIG. The vertical axis in FIG. 3 is the signal level, and the horizontal axis is time.

(2.1: Processing with odd frames)
First, in the initial state (this is referred to as “when the first frame is acquired”), in the imaging unit 1 (CMOS type image sensor) of FIG. Then, the charge accumulation time for the pixels in the even columns is set to be short. That is, odd-numbered columns of pixels are set as pixels belonging to the second pixel group, and even-numbered columns of pixels are set as pixels belonging to the first pixel group. This setting is performed by setting the first vertical register / shutter 14 and the second vertical register / shutter 15. In the imaging unit 1, the first vertical register / shutter 14 and the second vertical register / shutter 15 can easily perform different driving for each pixel, so that the shutter speed can also be set for each pixel. Such pixel-by-pixel control is difficult when a CCD is used as the image sensor.

The horizontal register 16 causes the switch transistors 17 arranged in the horizontal direction to be turned on by the horizontal register 16 for signals having a long charge accumulation time acquired from pixels in odd columns and signals having a short charge accumulation time acquired from pixels in even columns. Thus, the signal is output to the output terminal 19 via the output amplifier 18. An example of an output signal of the imaging unit 1 (CMOS type image sensor) is shown in FIG.
In FIG. 3, the signal of the portion with the odd number shown in the uppermost row indicates a long signal with a long charge accumulation time, and the signal with the even number indicates a short signal with a short charge accumulation time. . An output signal from the imaging unit 1 is separated into a long signal and a short signal by the L / S separation unit 3. FIG. 3B shows a long signal separated by the L / S separator 3, and FIG. 3C shows a short signal separated by the L / S separator 3.

The short signal output from the L / S separation unit 3 is the correction coefficient calculated by the correction value calculation unit 5 at the multiplication unit 6 (= (longer charge accumulation time) / (shorter charge accumulation time)). Is converted into a corrected short signal. FIG. 3D shows the modified short signal.
Next, the corrected short signal is interpolated by the interpolation unit 7 and converted into a signal having the same timing as the long signal output from the L / S separation unit 3. This converted signal is an interpolated long signal. FIG. 3E shows this interpolated long signal. Here, for example, the interpolation unit 7 generates an interpolated long signal by generating a signal obtained by averaging the two corrected short signals before and after, and matching the timing of the generated signal with the long signal. Specifically, a signal obtained by averaging the corrected short signal of the part (2) in FIG. 3 and the corrected short signal of the part (4) is generated, and the timing of the signal is set to the long of the part (3). By making it coincide with the signal, an interpolated long signal is created. In addition, a signal generated by simply delaying the modified short signal and matching the timing with the long signal may be used as the interpolated long signal.

The selection unit 8 selects the long signal output from the L / S separation unit 3 and the interpolation long signal output from the interpolation unit 7 based on the detection result of the saturation detection unit 4, so that the corrected long signal is obtained. Generated. This will be described with reference to FIG. In FIG. 3, the signal level indicated by the dotted line in FIG. 3 will be described as a predetermined value. In the parts (1), (3), (5), (7), and (13) where the long signal does not exceed the predetermined value, the long signal is selected by the selection unit 8, and the long signal is the modified long signal. Is output as In the portions (9) and (11) where the long signal exceeds the predetermined value, the selection unit 8 selects the interpolation long signal and outputs the interpolation long signal as a modified long signal. FIG. 3 (f) shows this modified long signal.
Finally, a signal synthesized by sequentially taking out the corrected short signal and the corrected long signal by the L / S synthesis unit 9 is output from the L / S synthesis unit 9 as a video signal. FIG. 3G shows this video signal. As can be seen from FIG. 3 (g), in the output signal from the imaging unit 1, the signals of the portions (9) and (11) where the signal level was saturated are reproduced without saturation, and a wide dynamic range is obtained. Is realized.

The above processing is performed until a video signal for one frame is acquired. The above processing is processing when an odd frame video signal is output, and the same processing is performed in each odd frame.
After the video signal for one frame (video signal for odd frames) is acquired, acquisition of the video signal for the next frame (video signals for even frames) is started.
(2.2: Processing with even frames)
The operation of the imaging device 100 in the even frame will be described below.
In the imaging unit 1 in FIG. 2, contrary to the first frame acquisition (odd frame acquisition), the charge accumulation time for the pixels in the even columns is set to be long, and the charge accumulation for the pixels in the odd columns is performed. Set the time to be shorter. That is, the pixels in the even columns are set as the pixels belonging to the second pixel group, and the pixels in the odd columns are set as the pixels belonging to the first pixel group. This setting is performed by setting the first vertical register / shutter 14 and the second vertical register / shutter 15.

  The horizontal register 16 causes the switch transistors 17 arranged in the horizontal direction to be turned on by a signal having a long charge accumulation time acquired from pixels in even columns and a signal having a short charge accumulation time acquired from pixels in odd columns. Thus, the signal is output to the output terminal 19 via the output amplifier 18. An example of an output signal of the imaging unit 1 (CMOS type image sensor) is shown in FIG. The signal waveform in FIG. 3 (a ') corresponds to FIG. 3 (a), which is a signal waveform in the case of an odd frame. That is, the signal waveform in the odd frame in the same pixel is FIG. 3A, and the signal waveform in the even frame is FIG. 3A. The same applies to FIGS. 3B to 3G and FIGS. 3A to 3G. That is, the signal waveforms of odd frames in the same pixel are FIGS. 3B to 3G, respectively, and the signal waveforms of even frames are FIGS. 3B 'to 3G', respectively.

3 (a ′) to (g ′), the signal of the portion where the number shown in the uppermost part of FIG. 3 is an even number indicates a long signal having a long charge accumulation time. The signal indicates a short signal having a short charge accumulation time. An output signal from the imaging unit 1 is separated into a long signal and a short signal by the L / S separation unit 3. FIG. 3B ′ shows the long signal separated by the L / S separator 3, and FIG. 3C ′ shows the short signal separated by the L / S separator 3.
The short signal output from the L / S separation unit 3 is the correction coefficient calculated by the correction value calculation unit 5 at the multiplication unit 6 (= (longer charge accumulation time) / (shorter charge accumulation time)). Is converted into a corrected short signal. FIG. 3D 'shows a modified short signal.

  Next, the corrected short signal is interpolated by the interpolation unit 7 and converted into a signal having the same timing as the long signal output from the L / S separation unit 3. This converted signal is an interpolated long signal. FIG. 3 (e ') shows this interpolated long signal. Here, for example, the interpolation unit 7 generates an interpolated short signal by generating a signal obtained by averaging the two corrected short signals before and after, and matching the timing of the generated signal with the long signal. Specifically, a signal obtained by averaging the corrected short signal of the part (3) in FIG. 3 and the corrected short signal of the part (5) is generated, and the timing of the signal is set to the long of the part (4). By making it coincide with the signal, an interpolation short signal is created. In addition, a signal generated by simply delaying the corrected short signal and matching the timing with the long signal may be used as the interpolated short signal.

The selection unit 8 selects the long signal and the interpolated long signal output from the L / S separation unit 3 based on the detection result of the saturation detection unit 4, thereby generating a modified long signal. This will be described with reference to FIG. In FIG. 3, the signal level indicated by the dotted line in FIG. 3 will be described as a predetermined value. In the parts (2), (4), (6), and (12) where the long signal does not exceed the predetermined value, the long signal is selected by the selector 8 and the long signal is output as a modified long signal. . In the portions (8) and (10) where the long signal exceeds the predetermined value, the selection unit 8 selects the interpolation long signal, and the interpolation long signal is output as a modified long signal. FIG. 3 (f ′) shows this modified long signal.
Finally, a signal synthesized by sequentially taking out the corrected short signal and the corrected long signal by the L / S synthesis unit 9 is output from the L / S synthesis unit 9 as a video signal. FIG. 3G shows this video signal. As can be seen from FIG. 3 (g), in the output signal from the imaging unit 1, the signals of the portions (9) and (11) where the signal level was saturated are reproduced without saturation, and a wide dynamic range is obtained. Is realized.

The above processing is performed until a video signal for one frame is acquired. Then, when the processing in the even frame is completed, the processing of the odd frame is executed, and thereafter, these processing is repeated.
The above processing is performed until a video signal for one frame is acquired. The above processing is processing when an odd frame video signal is output, and the same processing is performed in each odd frame.
After the video signal for one frame (video signal for odd frames) is acquired, acquisition of the video signal for the next frame (video signals for even frames) is started.
If the length of the charge accumulation time is fixed in the same pixel of the imaging unit 1, an error occurs in the video signal acquired by the pixel for which the short charge accumulation time is set, and when this video signal is displayed on the display device, A fixed pattern occurs in the display image (video), resulting in an unsightly display image (video). In the imaging device 100 according to the present invention, in the same pixel of the imaging unit 1, the charge accumulation time is alternately switched between odd frame processing and even frame processing, so that a video signal acquired by the imaging device 100 is used. Is displayed on the display device, an error caused by the length of the charge accumulation time is switched for each frame, so that no fixed pattern is generated in the video displayed on the display device by this video signal. This is because an error for each frame included in the video signal acquired from the imaging device 100 is canceled due to a human afterimage effect when viewing the video.

As described above, the image pickup apparatus 100 according to the present invention can output a video signal with no degradation in resolution, and also for a moving image that changes drastically within a predetermined period (for example, a frame period or a field period). The occurrence of video (image) blur can be suppressed. Furthermore, since the video signal acquisition process at the pixels of the image pickup unit 1 is alternated for each frame, a fixed pattern that occurs when the video signal is displayed on the display device (the error of the video signal acquired at the pixels of the image pickup unit 1). (Fixed pattern noise) can be removed.
In the above description, the imaging apparatus 100 configured to separate the processing channels of the long signal and the short signal has been described. However, the long signal and the short signal are processed in time series (time division processing) by digital processing. The processing channel may not be separated.

Further, in the imaging unit 1, the configuration in which the pixels with long and short charge accumulation times are alternately arranged in the horizontal direction has been described. However, the configuration in which the pixels with long and short charge accumulation times are alternately arranged in the vertical direction is the same. It is clear that an effect can be obtained.
In the case where the present invention is applied to an imaging apparatus configured with RGB separate imaging units (CMOS type image sensors), such as a three-plate camera apparatus, the imaging apparatus 100 performs the processing of the imaging apparatus 100 shown in FIG. What is necessary is just to set it as the structure which provides a system | strain separately 3 RGB.
Further, although the imaging apparatus 100 of the present invention is configured to correct the level of the short signal, it goes without saying that the same effect can be obtained by correcting the level of the long signal.
[Other Embodiments]
In the description of the above embodiment, the imaging device 100 in the case where the first pixel group and the second pixel group are set for each column has been described. However, the present invention is not limited to this, and even frames and What is necessary is just to change the charge accumulation time in an odd frame. For example, the first pixel group and the second pixel group are set for each row, or the first pixel group and the second pixel group are set randomly. It may be a thing.

In the description of the above embodiment, the imaging apparatus 100 has been described based on the frame period. However, the field period may be used instead of the frame period.
In the imaging device described in the above embodiment, each block may be individually made into one chip by a semiconductor device such as an LSI, or may be made into one chip so as to include a part or the whole.
Here, although LSI is used, it may be called IC, system LSI, super LSI, or ultra LSI depending on the degree of integration.
Further, the method of circuit integration is not limited to LSI, and implementation with a dedicated circuit or a general-purpose processor is also possible. 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, if integrated circuit technology comes out to replace LSI's as a result of the advancement of semiconductor technology or a derivative other technology, it is naturally also possible to carry out function block integration using this technology. Biotechnology can be applied as a possibility.
Moreover, each process of the said embodiment may be implement | achieved by hardware, and may be implement | achieved by software. Further, it may be realized by mixed processing of software and hardware.
The specific configuration of the present invention is not limited to the above-described embodiment, and various changes and modifications can be made without departing from the scope of the invention.

  The image pickup apparatus according to the present invention can expand the dynamic range without degrading the resolution, and is useful in the field of video equipment-related industries. Particularly, the image pickup apparatus for tunnels and security that require a high dynamic range. The imaging device according to the present invention can be implemented in this field.

1 is a configuration diagram of an imaging apparatus 100 according to a first embodiment of the present invention. The block diagram of the imaging part 1, the drive part 2, and the switch part 12 which concern on 1st Embodiment of this invention. Waveform diagram for explaining the operation of the imaging apparatus 100 according to the first embodiment Configuration diagram of conventional imaging device Explanatory diagram of dynamic range expansion of imaging device Operation waveform diagram of conventional imaging device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image pick-up part 2 Drive part 3 L / S separation circuit part 4 Saturation detection circuit part 5 Correction value calculation circuit part 6 Multiplier multiplication part 7 Interpolation circuit part 8 Selection circuit part 9 L / S composition circuit part 10 Process part 11 Timing generator Unit 12 Switching unit 13 Pixel 14 First vertical register / shutter 15 Second vertical register / shutter 16 Horizontal register 17 Transistor switch 18 Output amplifier 19 Output terminal

Claims (10)

An imaging device including a plurality of pixels capable of setting different charge accumulation times for each pixel, the first pixel group including the pixels, and the pixels not included in the first pixel group An image pickup unit including an image sensor including a second pixel group configured to obtain an image signal by converting light from a subject into an electric signal;
A charge storage time setting unit that sets a first charge storage time and a second charge storage time that is longer than the first charge storage time as the charge storage time of the first pixel group and the second pixel group;
A switching unit that switches the first charge accumulation time and the second charge accumulation time for each unit image acquisition period;
A drive unit that drives the imaging unit based on the first charge accumulation time and the second charge accumulation time switched by the switching unit for each unit image acquisition period;
The video signal output from the imaging unit is converted into a short signal that is the video signal acquired by the first charge accumulation time and a long signal that is the video signal acquired by the second charge accumulation time. An L / S separator to separate;
A saturation detector for detecting a signal level of the long signal;
A correction value calculation unit that calculates a correction value for correcting the signal level of the short signal to the signal level of the long signal based on the first charge accumulation time and the second charge accumulation time;
A multiplier for obtaining a modified short signal by multiplying the short signal by the correction value calculated by the correction value calculator;
An interpolator that interpolates the modified short signal and obtains an interpolated long signal that is a signal having the same timing as the long signal;
When the saturation detection unit determines that the signal level of the long signal is less than or equal to a predetermined value, the long signal is selected, and the saturation detection unit determines that the signal level of the long signal exceeds a predetermined value. A selection unit that selects the interpolated long signal and obtains the selected signal as a modified long signal;
An L / S synthesis unit that generates an output video signal by sequentially switching a modified long signal output from the selection unit and a modified short signal output from the multiplication unit;
An imaging apparatus comprising: The unit image acquisition period is one frame period.
The imaging device according to claim 1. The image sensor is configured by the pixels in a plurality of rows and columns, the first pixel group is configured by the pixels in an odd number column, and the second pixel group is configured by the pixels in an even number column.
The imaging device according to claim 1 or 2. The imaging device is configured by a plurality of rows and a plurality of columns of the pixels, the first pixel group is configured by the even columns of the pixels, and the second pixel group is configured by an odd columns of the pixels.
The imaging device according to claim 1 or 2. The imaging device is configured by the pixels in a plurality of rows and columns, the first pixel group is configured by the pixels in odd rows, and the second pixel group is configured by the pixels in even rows.
The imaging device according to claim 1 or 2. The imaging device is configured by the pixels in a plurality of rows and columns, the first pixel group is configured by the pixels in even rows, and the second pixel group is configured by the pixels in odd rows.
The imaging device according to claim 1 or 2. The image sensor is a CMOS image sensor.
The imaging device according to claim 1. An imaging device including a plurality of pixels capable of setting different charge accumulation times for each pixel, the first pixel group including the pixels, and the pixels not included in the first pixel group An imaging method including an imaging device including a second pixel group configured by: an imaging device including an imaging unit that acquires a video signal by converting light from a subject into an electrical signal;
A charge storage time setting step of setting a first charge storage time and a second charge storage time that is longer than the first charge storage time as the charge storage time of the first pixel group and the second pixel group;
A switching step of switching the first charge accumulation time and the second charge accumulation time for each unit image acquisition period;
A driving step of driving the imaging unit based on the first charge accumulation time and the second charge accumulation time switched for each unit image acquisition period by the switching step;
The video signal output by the imaging step is converted into a short signal that is the video signal acquired by the first charge accumulation time and a long signal that is the video signal acquired by the second charge accumulation time. An L / S separation step to separate;
A saturation detection step of detecting a signal level of the long signal;
A correction value calculating step for calculating a correction value for correcting the signal level of the short signal to the signal level of the long signal based on the first charge accumulation time and the second charge accumulation time;
A multiplication step of obtaining a modified short signal by multiplying the short signal by the correction value calculated in the correction value calculating step;
An interpolation step of interpolating the modified short signal to obtain an interpolated long signal that is a signal having the same timing as the long signal;
When it is determined by the saturation detection step that the signal level of the long signal is less than or equal to a predetermined value, the long signal is selected, and the saturation detection unit determines that the signal level of the long signal exceeds a predetermined value A selection step of selecting the interpolated long signal and obtaining the selected signal as a modified long signal,
An L / S synthesis step for generating an output video signal by sequentially switching between a modified long signal output from the selection step and a modified short signal output from the multiplier;
An imaging method comprising: An imaging device including a plurality of pixels capable of setting different charge accumulation times for each pixel, the first pixel group including the pixels, and the pixels not included in the first pixel group An integrated circuit that is used together with an imaging unit that acquires an image signal by converting light from a subject into an electrical signal,
A charge storage time setting unit that sets a first charge storage time and a second charge storage time that is longer than the first charge storage time as the charge storage time of the first pixel group and the second pixel group;
A switching unit that switches the first charge accumulation time and the second charge accumulation time for each unit image acquisition period;
A drive unit that drives the imaging unit based on the first charge accumulation time and the second charge accumulation time switched by the switching unit for each unit image acquisition period;
The video signal output from the imaging unit is converted into a short signal that is the video signal acquired by the first charge accumulation time and a long signal that is the video signal acquired by the second charge accumulation time. An L / S separator to separate;
A saturation detector for detecting a signal level of the long signal;
A correction value calculation unit that calculates a correction value for correcting the signal level of the short signal to the signal level of the long signal based on the first charge accumulation time and the second charge accumulation time;
A multiplier for obtaining a modified short signal by multiplying the short signal by the correction value calculated by the correction value calculator;
An interpolator that interpolates the modified short signal and obtains an interpolated long signal that is a signal having the same timing as the long signal;
When the saturation detection unit determines that the signal level of the long signal is less than or equal to a predetermined value, the long signal is selected, and the saturation detection unit determines that the signal level of the long signal exceeds a predetermined value. A selection unit that selects the interpolated long signal and obtains the selected signal as a modified long signal;
An L / S synthesis unit that generates an output video signal by sequentially switching a modified long signal output from the selection unit and a modified short signal output from the multiplication unit;
An integrated circuit comprising: An imaging device including a plurality of pixels capable of setting different charge accumulation times for each pixel, the first pixel group including the pixels, and the pixels not included in the first pixel group An image pickup unit including an image sensor including a second pixel group configured to obtain an image signal by converting light from a subject into an electric signal;
A charge storage time setting unit that sets a first charge storage time and a second charge storage time that is longer than the first charge storage time as the charge storage time of the first pixel group and the second pixel group;
A switching unit that switches the first charge accumulation time and the second charge accumulation time for each unit image acquisition period;
A drive unit that drives the imaging unit based on the first charge accumulation time and the second charge accumulation time switched by the switching unit for each unit image acquisition period;
The video signal output from the imaging unit is converted into a short signal that is the video signal acquired by the first charge accumulation time and a long signal that is the video signal acquired by the second charge accumulation time. An L / S separator to separate;
A saturation detector for detecting a signal level of the long signal;
A correction value calculation unit that calculates a correction value for correcting the signal level of the short signal to the signal level of the long signal based on the first charge accumulation time and the second charge accumulation time;
A multiplier for obtaining a modified short signal by multiplying the short signal by the correction value calculated by the correction value calculator;
An interpolator that interpolates the modified short signal and obtains an interpolated long signal that is a signal having the same timing as the long signal;
When the saturation detection unit determines that the signal level of the long signal is less than or equal to a predetermined value, the long signal is selected, and the saturation detection unit determines that the signal level of the long signal exceeds a predetermined value. A selection unit that selects the interpolated long signal and obtains the selected signal as a modified long signal;
An L / S synthesis unit that generates an output video signal by sequentially switching a modified long signal output from the selection unit and a modified short signal output from the multiplication unit;
An integrated circuit comprising:

Images