JPH05292389A - Image pickup device - Google Patents

Abstract

PURPOSE:To obtain a desired brightness at a desired part by switching a weighted area in accordance with the power of an optical system at the time of adjusting a diaphragm based on the result of weighting processing corresponding to the weighted area of a video signal. CONSTITUTION:A CPU 10 takes in position information of a zoom lens 8 from a zoom position detecting circuit 12 to detect the power of the optical system. When the power is low, the CPU 10 switches reference data VWG to HON so that a flat area (ARF) of a weighted signal is reduced. When the power is medium or high, the CPU switches data VWG to HON so that ARF is increased in accordance with the power, and the brightness of a picked-up image is detected to control a diaphragm 6. Thus, the area having the optimum brightness is obtained by switching in accordance with switching of the power, and the desired brightness is obtained while giving priority to a desired object.

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 Techniques Problems to be Solved by the Invention Means for Solving the Problems (FIGS. 1 to 6) Action (FIGS. 1 to 6) Example (1) Overall Configuration (FIG. 1) (2) ) Digital signal processing circuit (FIG. 2) (3) Weighting coefficient generation circuit (FIGS. 3 and 4) (4) Signal level detection circuit (FIG. 5) (5) Central processing unit (FIGS. 6 to 9) (6) Effects of Examples (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 apparatus, a picked-up image is divided into predetermined regions and the aperture is adjusted. That is, in this type of image pickup device, the picked-up image is divided into predetermined regions, and the signal level of the image pickup signal is weighted by the weighting coefficient assigned to each region. Further, in the image pickup apparatus, the weighting results are cumulatively added, and the aperture is adjusted based on the addition result. In this way, the aperture can be adjusted around the predetermined area of the captured image, and the usability for the user can be improved.

[0004]

By the way, when the captured image is divided and the aperture is adjusted in this way, the optimum brightness can be obtained for the portion desired by the user for a specific subject. However, in the case of this method, there is a case where the desired brightness cannot be obtained for the portion desired by the user depending on the imaged object, and there is a problem that the usability is poor accordingly. The present invention has been made in view of the above points, and an object thereof is to propose an imaging device capable of obtaining a desired brightness for a portion desired by a user.

[0005]

In order to solve such a problem, according to the present invention, an image pickup means 2 for picking up an image of a subject through predetermined optical systems 6 and 8 and outputting an image pickup signal S1, and an image pickup signal SR to. A weighting signal generation circuit 60 for generating a weighting signal WGT whose value changes according to a predetermined weighting region corresponding to SB, a weighting circuit 80 for weighting the image pickup signals SR to SB with the weighting signal WGT, and a weighting circuit 80. A diaphragm control circuit 10 that controls the apertures 6 of the optical systems 6 and 8 based on the output signal to control the brightness of the captured image, and a zoom position that detects the magnification of the optical systems 6 and 8 and outputs the magnification detection result. The detection means 12 and the area switching circuit 10 for switching the weighting area according to the result of magnification detection are provided.

[0006]

When the image pickup signals SR to SB are weighted by the weighting signal WGT whose value changes according to the weighting area and the aperture is adjusted based on the processing result, the weighting area is set according to the magnification of the optical systems 6 and 8. If switched, optical systems 6 and 8
It is possible to switch the region of optimum brightness by following the switching of the magnification of.

[0007]

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 device as a whole, which drives a solid-state image pickup device (CCD) 2 to pick up an image of a desired subject.

That is, the image pickup apparatus 1 generates a reference signal by the timing generator (TD) 4 and drives the solid-state image pickup element 2 with this reference signal. The image pickup apparatus 1 has a diaphragm 6 and a zoom lens 8 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. ing.

At this time, the central processing unit (CPU) 10
The zoom position detection circuit 12 detects the magnification of the captured image, and the control of the diaphragm 6 is switched based on the detection result, so that the subject is imaged with the brightness desired by the user even when the magnification is changed. It is designed to be able to do.

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 and outputs the color signal at a predetermined amplification rate. At this time, the signal level of each color signal is corrected so that the shading correction can be performed. In addition, the white balance adjustment and the gain adjustment 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 as to adjust the black set, the black balance, the white balance, the iris, and the flare correction. 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 FIG. 1, the correction signal SH generated by the digital signal processing circuit 20 is used to perform the shading correction.

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 its video signal.

(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 and the selectors 32R, 32G, 32B and 34R, 34G, 3G, and 3G.
4B, and at this time, the test signal is switched based on the output signal of the central processing unit 10. As a result, the digital signal processing circuit 20 can adjust the AV block and the like using various test signals in the adjustment mode, and can confirm the entire operation 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 adjustments can be easily performed.

The defect automatic 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 this defective pixel according to the contents of this memory circuit, thereby generating a color signal for correction from the surrounding pixels for the defective pixel, and Replace the signal with the generated color signal. As a result, the defect correction circuit 38
Is designed so that even if a defect occurs in the solid-state image sensor 2, the image quality is not significantly deteriorated.

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 is switched at this time, the signal level of the output signal is lowered to 0 level by switching the contact. 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 48 removes noise components from the color signal output from the defect correction circuit 38 by suppressing high-frequency components, and outputs the color signals. The shading correction circuits 50 and 52 generate the shading correction signals SH1 and SH2 for correcting the shading of the black level and the white level, respectively, based on the output signal of the low-pass filter circuit 48. At this time, the shading correction circuit 52 calculates the calculation result D of the central processing unit 10.
Based on 1, the correction signal SH2 for shading correction is created from each color signal.

As a result, the digital signal processing circuit 20
Outputs the shading correction signals SH1 and SH2 to the AV
It is designed to return to the block 16 to correct the shading. At this time, the shading correction circuit 50
Outputs the correction signal SH1 via the selectors 34R to 34B, and the selectors 34R to 34B selectively output the test signal instead of the correction signal SH1 in response to the selection signal SEL2. As a result, in the image pickup apparatus 1, the shading correction and the test signal can be selectively output as needed to simplify the work of adjusting the AV block.

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) Weighting coefficient generation circuit As shown in FIG. 3, the data detection circuit 54 generates the weighting signal WGT by the weighting signal generation circuit 60, and the image pickup apparatus 1 uses the weighting signal WGT to stop the aperture. Adjust 6. That is, the weighting signal generation circuit 60 gives a vertical synchronization signal to the V counter 64, and
4 and H counter 66 are supplied with a horizontal synchronizing signal.

The V counter 64 resets the count value with the vertical synchronizing signal and then sequentially counts the horizontal synchronizing signal, thereby outputting the count value representing the raster scanning position in the vertical scanning direction. On the other hand, the H counter 66 resets the count value with the horizontal synchronizing signal and then sequentially counts a predetermined clock signal, thereby outputting the count value representing the raster scanning position in the horizontal scanning direction.

The comparison circuit 68 outputs the comparison result with respect to the count value of the V counter 64 with the comparison reference VRS as a reference, and thereby raises the output signal level of the V counter 64, whereby in the vertical scanning direction. , A gate signal whose signal level rises from a predetermined position determined by the comparison reference VRS. The comparison circuit 70 has an H
Two comparison criteria hs regarding the count value of the counter 66
The comparison result is output on the basis of t and hgt, whereby two comparison standards hst and hst in the horizontal scanning direction are output.
A gate signal whose signal level rises in a region determined by gt is generated.

As a result, as shown in FIG. 4, the weighting signal generating circuit 60 adjusts the area inside the picked-up image M by a predetermined distance from the left and right sides and the upper side based on the output signals of the comparing circuits 68 and 70. It can be set in the area ARS. The coefficient generating circuit 72 outputs the first and second reference data VW output from the central processing unit 10.
Upon receiving G and VON, a predetermined clock signal is counted based on the output signal of the comparison circuit 68. As a result, the coefficient generation circuit 72 holds the 0 level up to the aperture adjustment area ARS in the vertical scanning direction, and then the signal level rises with the slope determined by the second reference data VON, and the aperture adjustment area ARS is set to the lower side from the lower side. A vertical weighting signal is generated in which the signal level is maintained at a constant level by the width determined by the reference data VWG of 1.

The coefficient generating circuit 74 has a central processing unit 1
The third and fourth reference data HWG and HON output from 0 are received, and a predetermined clock signal is counted with the output signal of the comparison circuit 60 as a reference, thereby generating a weighting signal in the horizontal scanning direction. Here, the weighting signal in the horizontal scanning direction is the aperture adjustment area A in the horizontal scanning direction.
After being held at 0 level up to RS, the fourth reference data H
The signal level rises with an inclination determined by ON, and the signal level is held at a constant level in the central portion of the screen by the width determined by the third reference data HWG, and then the fourth reference data H.
After the signal level has fallen with a slope determined by ON, it is held at 0 level.

As a result, the weighting signal generation circuit 60 is
Within the aperture adjustment area ARS, the first to fourth reference data are respectively set in the horizontal scanning direction and the vertical scanning direction with the center of the screen centered in the horizontal scanning direction and the lower side of the screen centered in the vertical scanning direction. Is used to generate a weighting signal whose signal level changes.

The selecting circuit 76 selects and outputs a weighting signal having a smaller signal level in the raster scanning order with respect to the weighting signals in the vertical scanning direction and the horizontal scanning direction. As a result, the weighting signal generation circuit 60 is configured to generate the weighting signal WGT in which the signal level rises in a trapezoidal shape in the central portion on the lower side of the screen of the captured image.

(4) Signal Level Detection Circuit As shown in FIG. 5, in the data detection circuit 54, the signal level detection circuit 80 detects the brightness of the picked-up image using the weighting signal WGT. That is, the signal level detection circuit 80 supplies the color signals SR to SB to the nameye circuit 82, and the signal having the highest signal level among the color signals SR to SB is selectively output in the repetition cycle of the color signals SR to SB. (Hereinafter, this signal will be referred to as the Namai signal).

The gate circuit 86 selectively outputs the Numay signal input through the latch circuit 84 with reference to the gate signal GT2, thereby selecting the Numay signal in the video period and outputting it to the subsequent latch circuit 88. Adder circuit 90
Adds the weighting signal WGT to the numeye signal obtained via the latch circuit 88 and slices the added signal at a predetermined signal level.

As a result, the adder circuit 90 performs weighting processing on the Numay signal with the weighting signal WGT,
The video signal of the aperture adjustment area ARS is divided into areas determined by the weighting signal WGT and then weighted for each area.

At this time, in the image pickup apparatus 1, the weighting signal WGT is made to rise except for the left and right end portions of the picked-up image and the upper part of the screen.
This portion can be weighted so as to have an extremely small signal level, so that when controlling the diaphragm 6, for example, the influence of the brightness of the sky in the background portion can be avoided.

Further, in the image pickup apparatus 1, in the weighting signal WGT, the signal level is raised in a trapezoidal shape in the central portion on the lower side of the screen of the picked-up image, so that the aperture can be adjusted with emphasis on this portion. There is. That is, when a normal subject is imaged, by arranging the central subject in the central portion of the screen and focusing on this portion, aperture adjustment is performed,
Optimal brightness can be obtained.

Based on this diaphragm adjustment principle, the signal level detection circuit 80 adds the output signal of the addition circuit 90 to the addition circuit 9.
2 and the output signal of the adder circuit 92 is applied to the latch circuit 9
It feeds back through 4 as an addition input. As a result, the signal level detection circuit 80 has the addition circuit 92 and the latch circuit 94.
Form an integrating circuit, and the output signal of the adding circuit 90 is cumulatively added in units of fields.

The selector 96 selects and inputs the output signal of the latch circuit 94 at a predetermined timing and outputs it to the latch circuit 98. The latch circuit 98 feeds back the output signal through the selector 96. As a result, the latch circuit 98 takes in the cumulative addition result of the latch circuit 94 and holds it for a predetermined period.

The delay circuit 100 suppresses and outputs the high frequency component of the added output of the adder circuit 94, and the peak detection circuit 120 outputs the output signal of the delay circuit 100 within a predetermined area determined by the gate signals NDR1 and NDR2. Detect the peak value. The selector 122 uses the peak detection circuit 120.
Output signal of the selector 12 is selected and input at a predetermined timing and is output to the latch circuit 124.
The output signal is fed back and input via 2.

Thus, the latch circuit 124 takes in the peak value detected by the peak detection circuit 120 and holds it for a predetermined period. As a result, in the image pickup apparatus 1, the diaphragm 6 is controlled based on the cumulative addition result and the peak detection result latched by the latch circuits 98 and 124.

(5) Central processing unit Here, the central processing unit 10 repeats the processing procedure shown in FIG. 6 at a predetermined cycle, thereby controlling the diaphragm 6.

That is, in the central processing unit 10, in the aperture control, steps SP1 to S are used.
Moving to P2, the zoom position is detected here. That is, the central processing unit 10 detects the magnification of the optical system by taking in the position information of the zoom lens 8 from the zoom position detection circuit 12. Furthermore, depending on the magnification of this optical system,
The central processing unit 10 uses the first to fourth reference data VW.
Switch G to HON.

That is, as shown in FIG. 7, when the magnification is small, the central processing unit 10 has the first to fourth areas so that the area ARF where the signal level of the weighted signal is flat (hereinafter referred to as the emphasis area) becomes small. The reference data VWG to HON are switched. On the other hand, as shown in FIGS. 8 and 9,
When the magnification is medium and large, the first to fourth reference data V are set so that the emphasis area ARF becomes larger according to this magnification.
Switch between WG and HON.

That is, when the magnification is small, the size of the subject to be imaged by the cameraman is often small,
Optimal brightness is desirable for this small subject. On the other hand, when the magnification increases, the subject also often increases, and it is necessary to adjust the aperture centering on a large area corresponding to the size of the subject.

Therefore, in the central processing unit 10, the emphasis area ARF is increased according to the magnification.
The weighted area is switched, and the brightness of the captured image is detected by focusing on the subject desired by the user.

That is, the central processing unit 10 proceeds to step SP3 to fetch the cumulative addition result and the peak detection result from the latch circuits 98 and 124, thereby switching the weighting area according to the magnification and detecting the brightness of the picked-up image. To do. Subsequently, the central processing unit 10 proceeds to step SP4, where the aperture correction amount is detected based on the peak value and the cumulative addition result, and then proceeds to step SP5 to control the aperture 6 based on the detection result.

That is, in the central processing unit 10, the diaphragm 6 is controlled so that the cumulative addition result becomes a predetermined reference value, and at this time, the reference value is switched based on the comparison result of the peak value and the cumulative addition result.

That is, it is considered that there is a large difference between the peak value and the cumulative addition result, for example, when there is a partially bright portion such as a spotlight. In this case, the aperture 6 is set to be larger than the cumulative addition result. The brightness of the subject at the center is set to the optimum brightness by controlling the eyes.
On the contrary, when the difference between the peak value and the cumulative addition result is small, in this case, the brightness is uniform throughout, the diaphragm 6 is controlled according to the cumulative addition result.

At this time, by switching the area of the weighting signal in accordance with the magnification of the optical system, the image pickup apparatus 1 can control the brightness of the portion desired by the user, and thereby the portion desired by the user can be controlled. Can obtain the desired brightness. Thus, when the central processing unit 10 controls the diaphragm 6, it continues to step SP6.
Then, the processing procedure is finished.

(6) Effects of the Embodiments According to the above configuration, the focus area A is set according to the magnification of the optical system.
By switching the RF and controlling the diaphragm 6 centering on this emphasis area ARF, the diaphragm 6 can be controlled with emphasis on the emphasis area ARF, and thereby the optimum brightness for the subject desired by the cameraman can be obtained. You can

(7) Other Embodiments In the above-described embodiments, the weighting signal is generated so that the signal level rises in a trapezoidal shape at the lower center of the screen. However, the present invention is not limited to this. Various weighting signals can be used if desired.

Further, in the above-mentioned embodiment, the case where the weighting signals are added by the adding circuit 90 and then sliced by the predetermined reference value has been described, but the present invention is not limited to this, and it is possible to multiply by the weighting signals. The Namai signal may be weighted.

Further, in the above embodiment, the case where the aperture control is performed based on the peak value and the cumulative addition result has been described, but the present invention is not limited to this, and is widely applied to an image pickup apparatus which controls the aperture based on the weighting result. can do.

[0056]

As described above, according to the present invention, when the image pickup signal is weighted by the weighting signal whose value changes according to the weighting area, and the aperture is adjusted based on the processing result, the magnification of the optical system is changed. By switching the weighting region in accordance with this, it is possible to switch the region of the optimum brightness in accordance with the switching of the magnification of the optical system, and thereby obtain the desired brightness for the portion desired by the user. Can be obtained.

[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 weighting signal generation circuit.

FIG. 4 is a schematic diagram for explaining the operation.

FIG. 5 is a block diagram showing a signal level detection circuit.

FIG. 6 is a flow chart for explaining aperture control.

FIG. 7 is a schematic diagram showing a captured image.

FIG. 8 is a schematic diagram showing a captured image when the magnification is increased.

FIG. 9 is a schematic diagram showing a captured image when the magnification is further increased.

[Explanation of symbols]

1 ... Imaging device, 2 ... Solid-state imaging device, 6 ... Aperture, 1
0 ... Central processing unit, 12 ... Zoom position detection circuit, 16 ... AV block circuit, 18 ... Analog digital conversion circuit, 20 ... Digital signal processing circuit, 6
0: Weighting signal generation circuit, 80: Signal level detection circuit.

Claims (1)

[Claims] 1. An image pickup means for picking up an image of a subject through a predetermined optical system and outputting an image pickup signal, and a weighting signal for generating a weighting signal whose value changes according to a predetermined weighting region corresponding to the image pickup signal. A generation circuit, a weighting circuit for weighting the image pickup signal with the weighting signal, and an aperture control circuit for controlling the aperture of the optical system based on the output signal of the weighting circuit to control the brightness of the captured image. An image pickup apparatus comprising: a zoom position detection unit that detects a magnification of the optical system and outputs a magnification detection result; and an area switching circuit that switches the weighting area according to the magnification detection result.