JPH05292531A - Image pickup device - Google Patents

Abstract

PURPOSE:To automatically adjust the black level by detecting the black level of each color signal in every field and correcting correction data for pedestal level setting or that for flare correction based on this detection result. CONSTITUTION:When obtaining the detection result of the black level in every field, a central processing unit 10 generates correction data DP to output it to an adding circuit 140 for pedestal level setting so that the black level of color signals outputted to an encoder 26 is a prescribed value. Color signals SR to SB are converted to digital signals by an A/D conversion circuit 18 and are multiplied in multiplying circuits 42R to 42B by a flare correction signal DF to perform the flare correction, and the pedestal level is set by an adding circuit 140 of a video process circuit 24. The unit 10 corrects the setup level based on the black level detection result to generate correction data DP, and this data DP is added to color signals by the circuit 140 to set the black level together with the pedestal level.

Description

Detailed Description of the Invention

[0001]

[Table of Contents] The present invention will be described in the following order. Field of Industrial Application Conventional Technology Problem to be Solved by the Invention Means for Solving the Problem (FIGS. 1 to 5) Action (FIGS. 1 to 5) Example (1) Overall Configuration (FIG. 1) (2) ) Digital signal processing circuit (FIG. 2) (3) Gate signal generation circuit (FIG. 3) (4) Level detection circuit (FIG. 4) (5) Central processing unit (FIGS. 5 and 6) (6) Effect of the embodiment (7) Other Examples Effects of the Invention

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup device and can be applied to, for example, a television camera.

[0003]

2. Description of the Related Art Conventionally, in this type of image pickup device, the black level is prevented from fluctuating even when the amplification factor of the image pickup signal is switched by adjusting the black set.

That is, in this type of image pickup device, an image pickup signal output from a solid-state image pickup element is converted into a color signal and amplified to a predetermined level, and in response to an operation of a gain switching operator such as when a picked up image is dark. The amplification factor can be switched.

At this time, in the image pickup device, the correction data stored in advance in the memory circuit is converted into an analog signal and added / subtracted to / from the color signal to correct the signal level so that the black level becomes equal among the color signals. Further, by switching the correction data in response to the operation of the gain switching operator, the black level is prevented from changing.

[0006]

In the image pickup apparatus, the black level of each color signal is detected at the time of assembly, and the correction data is set based on the detection result. If this adjustment work can be automated, the work of assembling the image pickup apparatus can be simplified, which is considered to be convenient.

The present invention has been made in consideration of the above points, and it is an object of the present invention to propose an image pickup apparatus capable of automating this kind of adjustment work.

[0008]

In order to solve such a problem, in the first invention, an image pickup apparatus for picking up an image of a desired subject to obtain an image pickup signal S1, converting the image pickup signal S1 into a video signal SV and outputting the video signal SV. 1, the image pickup means 2 for outputting the image pickup signal S1 and the image pickup signal S1 for the color signals SR, SG, S.
The signal processing circuit 16 for converting to B and outputting the color signal S
An analog digital conversion circuit 18 for converting R, SG, SB into a digital signal and outputting the digital signal; a digital signal processing circuit 24 for correcting the pedestal level of the digital signal and converting the digital signal into a video signal SV for output.
26, a signal level detection circuit 90 that detects the signal level of the digital signal, and control that outputs correction data to the digital signal processing circuits 24 and 26 and sets the pedestal level based on the detection result of the signal level detection circuit 90. The signal level detection circuit 90 detects the black level of the digital signal in units of fields, and the control circuit 10 includes the circuit 10 based on the detection result of the black level.
Of the video signal SV so that the black level of
Set the pedestal level of the digital signal so that the black level of does not change between fields.

Further, in the second aspect of the invention, in the image pickup device 1 for picking up an image of a desired subject to obtain the image pickup signal S1, converting the image pickup signal S1 into the video signal SV and outputting the image signal SV, the image pickup means for outputting the image pickup signal S1. 2 and a signal processing circuit 1 for converting the image pickup signal S1 into color signals SR, SG, SB and outputting the color signals SR, SG, SB.
6, an analog digital conversion circuit 18 that converts the color signals SR, SG, SB into digital signals and outputs the digital signals, and corrects flare of the digital signals based on predetermined correction data DF and converts the digital signals into video signals SV. And output video signal processing circuits 20, 24 and 26, and a signal level detection circuit 9 for detecting the signal level of the digital signal.
0 and the detection result of the signal level detection circuit 90,
The correction data DF is supplied to the video signal processing circuits 20, 24 and 26.
The signal level detection circuit 90 detects the black level of the digital signal for each field, and the control circuit 10 determines the black level of the video signal SV based on the black level detection result. The correction data DF is output so that the value becomes a value and the black level of the video signal SV does not change between fields.

[0010]

The black level of the digital signal is detected for each field, and the black level of the video signal SV is set to a predetermined value based on the detection result, and the black level of the video signal SV is not changed between the fields. , Correction data DF
By outputting, it is possible to automate the adjustment work, and at the same time, it is possible to prevent the fluctuation of the black level between the fields.

Further, when the flare of the digital signal is corrected based on the correction data DF, the correction data is set so that the black level of the video signal becomes a predetermined value and the black level of the video signal SV does not change between fields. By outputting the DF, the flare correction can be performed, the black level adjustment work can be automated, and the variation between the black level fields can be prevented.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to the drawings.

(1) Overall Structure In FIG. 1, reference numeral 1 denotes an image pickup apparatus as a whole, which drives a solid-state image pickup element (CCD) 2 to pick up an image of a desired subject.

That is, the image pickup apparatus 1 generates a reference signal with the timing generator (TG) 4 and drives the solid-state image pickup element 2 with this reference signal. In the image pickup apparatus 1, a diaphragm 6 and a zoom lens 8 are arranged on the front surface of the solid-state image pickup element 2, so that an image of a subject is formed on the image pickup surface of the solid-state image pickup element 2 at a desired magnification and brightness.

At this time, the central processing unit (CPU) 10
Detects the magnification of the captured image with the zoom position detection circuit 12, and switches the control of the diaphragm 6 based on the detection result.
As a result, the subject can be imaged with the brightness desired by the user even when the magnification is changed.

Further, the image pickup apparatus 1 applies the correlated double sampling method to sample and hold the output signal of the solid-state image pickup element 2 by the sample / hold circuit (S / H) 14.
The resulting image pickup signal S1 is sent to the AV block circuit 16
Output to.

The AV block circuit 16 generates each color signal from the image pickup signal S1 and then amplifies it with a predetermined amplification factor. At this time, by correcting the signal level of each color signal, it is possible to perform the shading correction and the like. Furthermore, the gain can be adjusted by switching the amplification factor.

Analog digital conversion circuit (A / D) 1
8 is a color signal SR output from the AV block circuit 16
~ SB is converted into a digital signal and output.

The digital signal processing circuit 20 detects the signal levels of the respective color signals SR to SB by a predetermined detection circuit so that the black set adjustment, the black balance adjustment, the white balance adjustment, the aperture adjustment, and the flare correction are performed. A data detection process for the CPU is executed, and the detection result is output to the central processing unit 10 as needed. As a result, in the image pickup apparatus 1, the central processing unit 10 controls each signal processing circuit based on the data detection result, so that the white balance can be adjusted.

Further, the digital signal processing circuit 20 corrects the signal level of each color signal based on the data detection result to perform flare correction and also generates a correction signal SH for shading correction. A via the digital analog conversion circuit (D / A) 22
Output to the V-block circuit 16. Thereby, the imaging device 1
In, the shading correction is performed using the correction signal SH generated by the digital signal processing circuit 20.

The video processing circuit 24 receives the color signals processed by the digital signal processing circuit 20, performs gamma processing and knee processing, and then sets the pedestal level. The subsequent encoder circuit 26 converts each color signal into a luminance signal and a color difference signal, and then converts into a video signal and outputs it.

As a result, the image pickup apparatus 1 can pick up an image of a desired subject and output the video signal SV.

(2) Digital signal processing circuit As shown in FIG. 2, in the digital signal processing circuit 20, the test signal generating circuit 30 generates various test signals TS and the selectors 32R, 32G, 32B and 34R, 34 are used.
The test signal is output based on the output signal of the central processing unit 10 at this time. As a result, the digital signal processing circuit 20
In the adjustment mode, various test signals T are required as necessary.
The S block can be used to adjust the AV block circuit 16 and the like, and the entire operation can be confirmed in the self-diagnosis mode.

Further, the digital signal processing circuit 20 supplies the respective color signals SR to SB which are digital signals to the clamp level detection circuit 36, and detects the signal levels of the respective color signals SR to SB at a predetermined timing. Further, the digital signal processing circuit 20 outputs the signal level detection result to a clamp circuit (not shown), thereby setting the clamp level of each color signal SR to SB.

In the normal operation mode, the selectors 32R to 32B select the color signals SR to SB and output them to the defect correction circuit 38, whereas in the self-diagnosis mode, the contacts are switched at a predetermined timing. Therefore, during one horizontal scanning period of the vertical blanking period, the color signal SR
The test signal is selectively output instead of SB. On the other hand, in the adjustment mode, the selectors 32R to 32B are controlled by the central processing unit 10 to switch the contact at a predetermined timing according to each adjustment item, whereby the color signal SR in the imaging device 1 is changed. ~ SB is used to output various test signals, so that various items can be easily adjusted.

The automatic defect detection circuit 40 detects a defective pixel of the solid-state image pickup device 2 by continuously monitoring the signal level of each color signal, and stores the position of this defective pixel in a predetermined memory circuit. The defect correction circuit 38 executes interpolation calculation processing at the position of the defective pixel according to the contents of this memory circuit. As a result, the defect correction circuit 38 generates a color signal for correction from the surrounding pixels for the defective pixel, and replaces the color signal of the defective pixel with the generated color signal. As a result, the defect correction circuit 38 does not significantly deteriorate the image quality even when a defect occurs in the solid-state image sensor 2.

The addition circuits 42R to 42B add the flare correction signal output from the flare correction circuit 44 to each color signal, thereby correcting the flare of the captured image. The flare correction circuit 44 is adapted to generate a flare correction signal based on the calculation result of the central processing unit 10, whereby the image pickup apparatus 1 can perform flare correction by a simple adjustment work.

The selectors 46R-46B are comprised of the adder circuit 42.
The output signals of R to 42B are output to the subsequent video process circuit 24, and when the signal level of the selection signal SEL1 switches at this time, the contact is switched to lower the signal level of the output signal to 0 level. Thereby, the imaging device 1
In the adjustment mode or the like, the input level of the video process circuit 24 is lowered to 0 level if necessary, and the circuit blocks after the video process circuit 24 can be easily adjusted.

The low-pass filter circuit (LPF) 48 is
With respect to the color signal output from the defect correction circuit 38, the high frequency component is suppressed to remove the noise component and output. The shading correction circuits 50 and 52 generate the shading correction signals SH1 and SH2 based on the output signal of the low-pass filter circuit 48. to correct.

At this time, the shading correction circuit 52
A correction signal SH2 for shading correction is created from each color signal based on the calculation result D1 of the central processing unit 10. As a result, the digital signal processing circuit 20 feeds back the shading correction signals SH1 and SH2 to the AV block circuit 16 for shading correction.

At this time, the shading correction circuit 50 is
The correction signal SH1 is output via the selectors 34R to 34B, and the selectors 34R to 34B are configured to selectively output the test signal instead of the correction signal SH1 when the selection signal SEL2 rises. As a result, in the image pickup apparatus 1, the shading correction signal SH1 and the test signal are selectively output as needed, so that the adjustment work of the AV block circuit can be simplified.

The data detection circuit 54 detects data for flare correction and white balance adjustment by detecting the signal level of the output signal of the low-pass filter circuit 48. Regarding the data for aperture adjustment, the data detection circuit 54 stores the data of the detection result in the memory circuit of the defect detection circuit 38, and the contents of this memory circuit can be accessed from the central processing unit 10 and easily. The aperture can be adjusted.

(3) Gate Signal Generation Circuit Further, the data detection circuit 54 generates a gate signal for data detection by the gate signal generation circuit 68 shown in FIG. Thus, in the white balance adjustment mode, the gate signal generation circuit 68 outputs the gate signal GT1 based on the signal level of the luminance signal ADY to set the white balance adjustment region, while in the self-diagnosis mode. In the adjustment mode, the timing for detecting the test signal can be set.

That is, the gate signal generation circuit 68 supplies the luminance signals ADY to the comparison circuits 70 and 72, and outputs the comparison result based on the predetermined comparison reference PK and LOW. Here, the comparison reference PK and LOW can be set by the central processing unit 10 according to the operation mode. In the white balance adjustment mode, the peak level detected by the peak level detection circuit (not shown) can be set. While the first comparison reference PK is set as a reference, a level lower than the first comparison reference PK by a predetermined level is set as the second comparison reference LOW.

As a result, the comparison circuits 70 and 72 detect the area of the brightness level within the range from the first to the second comparison reference and output the detection result as the level gate LVGT. Thus, in the gate signal generation circuit 68, the first and second comparison reference PK
By switching between LOW and LOW, various gate signals LVGT can be generated based on the signal level of the luminance signal ADY.

Further, in the gate signal generating circuit 68, the V counter 74 is supplied with the vertical synchronizing signal VD, and the V counter 74 and the H counter 76 are also provided with the horizontal synchronizing signal HD. The V counter 74 resets the count value with the vertical synchronizing signal VD and then sequentially counts the horizontal synchronizing signal HD, thereby outputting a count value representing the raster scanning position in the vertical scanning direction. On the other hand, the H counter 76 resets the count value with the horizontal synchronizing signal HD and then sequentially counts a predetermined clock signal, thereby outputting a count value representing the raster scanning position in the horizontal scanning direction.

The comparison circuit 78 raises the signal level of the output signal when the count value of the V counter 74 falls within the range of these two comparison references UP and DWN with reference to the two comparison references UP and DWN, and Thus, a gate signal whose signal level rises at a predetermined raster scanning position in the vertical scanning direction is generated. Similarly, the comparison circuit 80 uses the two comparison references LFT and RGT as a reference, and the count value of the H counter 76 is the two comparison references LFT and RG.
When it falls within the range of T, the signal level of the output signal rises, thereby generating a gate signal whose signal level rises at a predetermined raster scanning position in the horizontal scanning direction.

Thus, the gate signal generating circuit 68 can generate various gate signals WHGT whose signal level rises in a predetermined area of the picked-up image.

Here, the comparison reference U of the comparison circuits 78 and 80 is used.
P, DWN and LFT, RGT are central processing units 1
Therefore, the gate signal generation circuit 68 can switch the timing of the gate signal WHGT in accordance with the operation mode.

The selector 82 switches its operation based on the control signals ARE0 to ARE2 output from the central processing unit 10, and in the self-diagnosis mode or the like, the gate signal WHGT or blanking signal output from the comparison circuits 78 and 80. BLK is selectively output, while in the white balance adjustment mode, the level gate LVG is output.
Select and output T.

As a result, the gate signal generation circuit 68 can select the comparison output of the comparison circuits 78 and 80, for example, and output the gate signal GT1 whose signal level rises in a desired one horizontal scanning period during the vertical blanking period. As opposed to
The gate signal GT1 whose signal level rises during the video period can be output by selecting the comparison output of the comparison circuit 78.

In this embodiment, the gate signal generation circuit 68 outputs the selection output of the selector 82 to the gate circuit 86.
To the first and second gate signals CLR and LC from the selected output in response to the mode switching signals MSL0 to MSL2 output from the central processing unit 10.
It is designed to generate H. Thus, in the gate signal generation circuit 68, the gate signals CLR and LCH are selectively used according to the operation mode to simplify the adjustment work and to confirm the operation mode and the like.

(4) Level Detection Circuit As shown in FIG. 4, the level detection circuit 90 uses the gate signal G
Various signals are detected with T1 as a reference, whereby in the white balance adjustment mode, the signal level difference between the red and blue color signals with respect to the green color signal is detected. That is, the level detection circuit 90 determines that each color signal SR
To SB are provided to the selector 92, and the selection signal is output via the latch circuit 94.

Here, in the selector 92, the contact is switched based on the control signal output from the central processing unit 10, whereby the selector 9 is used in this embodiment.
By switching the two contacts, the signal levels of the respective color signals SR to SB can be detected. As a result, the selector 92 switches the contacts in the field unit in the white balance adjustment mode and alternately outputs the red color signal SR and the blue color signal SB in the field unit. On the other hand, in the adjustment mode and the self-diagnosis mode, the contacts are sequentially switched in units of field,
As a result, the color signals SR to SB are sequentially and cyclically output.

In the selector 92, the output signal of the counter circuit 96 is input in addition to the color signals SR to SB, so that the reference signal rising at a three-field cycle is selected instead of the color signals SR to SB. It is designed to be able to output. The gate circuit 96 outputs the selected output of the selector 92 to the latch circuit 98 during the period when the signal level of the gate signal GT1 rises, thereby selecting the color signals SR and SB in the white balance adjustment area in the white balance adjustment mode. Output.

On the other hand, in the self-diagnosis mode and the adjustment mode, the gate circuit 96 similarly outputs the gate signal GT1.
The output signal of the latch circuit 94 is sent during the period in which the signal level rises, thereby selectively outputting the signals of one horizontal scanning period in the vertical blanking period, the video period, etc. for each color signal SR to SB. It is done like this.

The gate circuit 100 receives the green color signal SG via the latch circuit 102 and selectively outputs the green color signal SG to the latch circuit 104 during the period in which the signal level of the gate signal GT1 rises.

The subtraction circuit 106 includes selectors 10 respectively.
The output signals of the latch circuits 98 and 104 are received via 8 and 110, and the subtracted output is output to the addition circuit 112. As a result, in the white balance adjustment mode,
The level detection circuit 90 alternately outputs a first subtraction signal obtained by subtracting a green color signal from a red color signal and a second subtraction signal obtained by subtracting a green color signal from a blue color signal at a field cycle. It is designed to do.

On the other hand, in the adjustment mode and the self-selection mode, the selector 110 lowers the signal level of the output signal to 0 level, whereby the subtraction processing of the subtraction circuit 106 is stopped and controlled, for example, for black level adjustment. It is designed to detect data. In addition, in the level detection circuit 90, a predetermined subtraction output is input to the selector 108 in addition to the output signal of the latch circuit 98, whereby the contact of the selector 108 is switched,
The signal level of this subtraction output can be detected.

The adder circuit 112 outputs an output signal to the latch circuit 116 via the AND circuit 114, and feeds back the output signal of the latch circuit 116 as an addition input. In the AND circuit 114, the clear signal C is synchronized with the vertical synchronizing signal in the white balance adjusting mode.
LR is input, and as a result, the adder circuit 1
In 12, the output signal of the selector 108 is cumulatively added in the field cycle. As a result, the level detection circuit 90
In the above, the signal level difference between the red and blue color signals with respect to the green color signal in the white balance adjustment area is cumulatively added in the field cycle via the latch circuit 116.

On the other hand, in the self-diagnosis mode and the adjustment mode, the subtraction processing of the subtraction circuit 106 is stopped and controlled, so that the signal levels of the respective color signals SR to SB in the period in which the gate signal GT1 rises are in field units. The cumulative addition result is obtained.

The selectors 118 and 120 respectively switch the contacts at the field cycle, and thereby latch the cumulative addition results of the latch circuit 116 at the field cycles to the subsequent latch circuits 122 and 124, respectively. As a result, in the level detection circuit 90, in the white balance adjustment mode, the latch circuit 122 and 124 respectively add the signal level difference cumulative addition results of the red and blue color signals to the green color signal in the white balance adjustment area.
To the central processing unit 10
Output to. As a result, in the image pickup apparatus 1, white balance adjustment is performed so that the cumulative addition result becomes 0 level.

On the other hand, in the adjustment mode, the level detection circuit 90 sequentially and cyclically accumulates the cumulative addition results of the signal levels of the respective color signals during the rising period of the gate signal GT1 in the latch circuits 122 and 124. In this embodiment, the image pickup apparatus 1 adjusts each circuit block on the basis of the cumulative addition result.

In the self-diagnosis mode, the clear signal CLR input to the AND circuit 114 is the rising edge of the test signal TS inserted in the vertical blanking period.
The latch circuits 122 and 124 are adapted to accumulate the result of cumulative addition of the signal levels based on the rising timing of each clear signal CLR in response to the rising of the video period. .. As a result, in the image pickup apparatus 1, the test signal inserted in the vertical blanking period is monitored based on the cumulative addition result stored in the latch circuit 122, and based on the cumulative addition result stored in the latch circuit 124, By detecting the signal level during the video period, the abnormality of the circuit block can be detected by controlling the aperture 6, for example.

Further, in this embodiment, the level detection circuit 90 gives the output signal of the latch circuit 98 to the flip-flop circuit (FF) 126, which causes the flip-flop circuit 126 to perform white balance adjustment in the white balance adjustment mode, for example. In the range of the area,
A detection output in which the signal level rises for each pixel of the solid-state image sensor 2 is generated.

The counter 130 receives the signal from the flip-flop circuit 126 via the selector 128, and counts this output signal in the field cycle to detect the number of pixels during the period when the gate signal GT1 rises. Accordingly, in the image pickup apparatus 1, the latch circuit 12
The result of cumulative addition of 2 and 124 is divided by the count value of the counter 130 so that the signal level of each pixel can be easily detected.

In this embodiment, the selector 128
Switches the contacts based on a predetermined control signal CSL, whereby the level detection circuit 90 can output various count results as necessary in an operation mode other than the white balance adjustment mode.

With the switching of the operation of the selector 128, the output signal of the latch circuit 98 is input to the selector 128 via the comparison circuit 132.
In the comparison circuit 132, the central processing unit 10
The latch circuit 9 based on the comparison reference PRK set in
The comparison result is output for eight output signals. As a result, the level detection circuit 90 can set various reference levels as necessary and detect the number of pixels of each color signal exceeding the reference level.

(5) Central processing unit Here, the central processing unit 10 switches its operation based on serial data input through a predetermined jig during the assembly and maintenance of the image pickup apparatus 1, whereby the adjustment mode is set. Switch.

In this state, the central processing unit 10 executes a processing program corresponding to each adjustment item based on the subsequently input control data, and automatically adjusts each adjustment item.

Here, as shown in FIG. 5, in the black set adjustment, the central processing unit 10 makes the step SP1.
To step SP2, and after closing the diaphragm 6,
Move to step SP3.

Here, the central processing unit 10 outputs a control signal to the gate signal generating circuit 68, thereby setting the comparison reference LFT, RGT, UP, DWN and switching the contact of the selector 82. As a result, the central processing unit 10 generates the gate signal GT1 whose signal level rises in the effective region of the captured image, and then the step SP.
Go to 4.

Here, the central processing unit 10 fetches the cumulative addition results latched by the latch circuits 122 and 124, and then, the cumulative addition results are respectively counter 130.
Divide by the count value of. That is, in the image pickup apparatus 1, since the diaphragm 6 is completely closed,
It is possible to detect the black level for each pixel by dividing the cumulative addition result of the latch circuit 122 or 124 by the count value of the counter 130.

At this time, the central processing unit 10 is adapted to latch the cumulative addition results in the latch circuits 122 and 124, respectively, in units of fields, whereby the black level of the color signal is detected for even fields and odd fields. That is, in the output signal of the solid-state image sensor, the black level may vary between fields, and in this case, it is necessary to switch and adjust the black level for each field. Therefore, the central processing unit 10 detects the black level for the even field and the odd field,
The black level is corrected based on this detection result.

When this detection result is obtained, the central processing unit 10 shifts to the next step SP5 and generates the correction data DP so that the black level of the color signal output to the encoder 26 becomes the value 20H, This correction data DP is output to the adder circuit 140 for setting the pedestal level. Here, as shown in FIG. 6, in the AV block circuit 16, each color signal SR to SB is amplified by the gain amplifier 134 after the black level shading correction signal SH1 is added, and then amplified by the gain amplifier 134. The white level shading correction signal SH2 is multiplied.

Further, the color signals SR to SB are converted into digital signals by the subsequent analog digital conversion circuit 18, and then the flare correction signals DF are multiplied by the multiplication circuits 42R to 42B to correct flare, and the subsequent video process circuit 2
The pedestal level is set by the adder circuit 140 of 4. Here, in the central processing unit 10, the set-up level is corrected based on the black level detection result to generate the correction data DP, and this correction data DP is added to the color signal by the addition circuit 140,
The black level is set together with the pedestal level, and thus the black level is automatically adjusted with a simple configuration.

At this time, the central processing unit 10 also corrects the change in the black level generated between the fields by switching the correction data DP between the even field and the odd field based on the black level detection result.

That is, since this variation is repeated in the field cycle, it cannot be completely corrected in the state of, for example, an analog signal. However, if the correction data DP is switched to prevent the fluctuation as in this embodiment, it is possible to reliably prevent the fluctuation of the black level between the fields.

Subsequently, the central processing unit 10 stores the contents of the correction data DP in the memory circuit, and then proceeds to step SP6, where it is determined whether or not the black level has been set for all the color signals. In this case, since the negative result is obtained, the central processing unit 10 makes the step SP
7, the channel is switched and the process returns to step SP4. As a result, the central processing unit 10 becomes a step SP.
When the processing loop of 4-SP5-SP6-SP7-SP4 is repeated to correct the black level for all color signals,
When a positive result is obtained in step SP6, the process proceeds to step SP8.

Here, the central processing unit 10 judges whether or not the black level has been set for all the gains, and if a negative result is obtained in this case, the process proceeds to step SP9 to switch the gain of the gain amplifier 134. That is, in this embodiment, the image pickup apparatus 1 can switch the amplification factor of the color signal in two steps in 6 [dB] units as compared with the normal operation state by operating a predetermined operator. This makes it possible to increase the brightness of the entire screen. Therefore, when the adder circuit 132 or the like has an offset voltage, the black level also fluctuates as the gain is switched.

Therefore, in this embodiment, the central processing unit 10 adjusts the black level for each gain, stores the contents of the correction data DP in the memory circuit, and then executes step S.
Moving to P10, this processing procedure is ended. As a result, the central processing unit 10 switches the correction data DP for each gain in the operating state based on the content of the correction data DP stored in the memory circuit, thereby correcting the black level of each color signal and adjusting the black set. ..

At this time, the central processing unit 10 adjusts the black balance by setting the black level of each color signal to a predetermined reference level.

(6) Effects of the Embodiments With the above arrangement, the black level of each color signal is detected for each field, and the correction data for setting the pedestal level is corrected based on the black level detection result. By setting to a predetermined value, the black level adjustment work can be simplified with a simple structure, and the assembly work and maintenance work can be simplified accordingly, and at the same time, the black level variation between fields is prevented. be able to.

(7) Other Embodiments In the above-described embodiments, the correction data DP for setting the pedestal level is switched to prevent the black level variation between fields, but the present invention is not limited to this. Instead, the flare correction data DF may be switched to prevent the black level from changing. That is, in the flare correction data, the correction data D is calculated according to the amount of incident light.
By changing the value of F, the value of the correction data DF is offset based on the black level detection result, and thereby the black level is set to a predetermined level. At this time, the offset amount is switched for each field to prevent the black level from varying between fields. Even in this case, it is possible to automatically set the black level with a simple configuration, and at the same time, it is possible to prevent the black level from varying between fields.

Further, in the above-described embodiment, the case where the black level is detected and automatically adjusted in the effective area of the image pickup screen is described, but the present invention is not limited to this, and the black level is detected in the video period. The present invention can be widely applied in the case of adjusting by the above, and further, in the case of setting a predetermined area in the effective area and detecting the black level in this area.

Further, in the above embodiment, the case where each color signal is adjusted to a predetermined reference level has been described.
The present invention is not limited to this, and the black balance may be adjusted by setting this level with reference to the green color signal, for example.

[0077]

As described above, according to the present invention, the black level of each color signal is detected for each field, and the correction data for setting the pedestal level or the correction for flare correction is based on the black level detection result. By correcting the data, the black level can be automatically adjusted with a simple configuration, and at the same time, it is possible to obtain the image pickup apparatus capable of preventing the fluctuation of the black level between the fields.

[Brief description of drawings]

FIG. 1 is a block diagram showing an image pickup apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram showing the digital signal processing circuit.

FIG. 3 is a block diagram showing a gate signal generation circuit.

FIG. 4 is a block diagram showing a level detection circuit.

FIG. 5 is a flow chart used to explain black level adjustment.

FIG. 6 is a block diagram used for the explanation.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Imaging device, 2 ... Solid-state imaging device, 10 ... Central processing unit, 16 ... AV block circuit, 20 ... Digital signal processing circuit, 50 ... Shading correction circuit, 54 ... Data detection circuit, 68 ...... Gate signal generation circuit, 90 …… Level detection circuit.

Claims (2)

[Claims] 1. An image pickup device for picking up an image of a desired subject to obtain an image pickup signal, converting the image pickup signal into a video signal and outputting the video signal, and an image pickup means for outputting the image pickup signal, and a color signal for the image pickup signal. A signal processing circuit for converting and outputting, an analog digital converting circuit for converting and outputting the color signal into a digital signal, and a pedestal level of the digital signal is corrected, and the digital signal is converted into the video signal and output. A digital signal processing circuit for detecting the signal level of the digital signal, and based on the detection result of the signal level detection circuit, output correction data to the digital signal processing circuit to determine the pedestal level. And a control circuit for setting, wherein the signal level detection circuit sets the black level of the digital signal to a field. The control circuit switches the correction data for each field based on the detection result of the black level so that the black level of the video signal becomes a predetermined value and the black level of the video signal. The image pickup apparatus is characterized in that the pedestal level of the digital signal is set so that does not change between fields. 2. An image pickup device for picking up an image of a desired subject to obtain an image pickup signal, converting the image pickup signal into a video signal and outputting the video signal, and an image pickup means for outputting the image pickup signal, and the image pickup signal as a color signal. A signal processing circuit for converting and outputting, an analog digital converting circuit for converting and outputting the color signal into a digital signal, and a flare of the digital signal is corrected based on predetermined correction data, and the digital signal is converted into the video signal. A video signal processing circuit for converting into a signal and outputting the signal, a signal level detecting circuit for detecting the signal level of the digital signal, and outputting the correction data to the video processing circuit based on the detection result of the signal level detecting circuit. The signal level detection circuit detects the black level of the digital signal for each field, and The path switches the correction data for each field based on the detection result of the black level so that the black level of the video signal becomes a predetermined value and that the black level of the video signal does not change between fields. An image pickup device, which outputs the correction data.