JP3612762B2 - Imaging device - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to an imaging device, and improves the control characteristics of an auto iris circuit in a television camera or the like.
[0002]
[Prior art]
Conventionally, in this type of imaging apparatus, a part of the signal processing circuit is formed by a digital signal processing circuit, thereby simplifying adjustment work and the like. That is, in FIG. 4, reference numeral 1 denotes a television camera as a whole of a camera-integrated video tape recorder, which captures a desired subject and obtains a video signal SV. The video signal SV is stored in a video tape recorder housed in the same housing. Record.
[0003]
Here, the television camera 1 picks up an image of a subject through a lens 2 held interchangeably, and the light emitted from the lens 2 is red by a dichroic prism (not shown) arranged following the lens 2. It is decomposed into blue and green light LR, LG, LB. Furthermore, the television camera 1 condenses these red, blue, and green light LR, LG, and LB on the imaging surfaces of CCD (Charge Coupled Device) solid-state imaging devices (CCD) 3R, 3G, and 3B, respectively.
[0004]
Each of the CCD solid-state imaging devices 3R, 3G, and 3B is operated by a driving pulse of a timing generator (not shown), and outputs imaging signals SR, SG, and SB in which this driving pulse component is mixed in the imaging result.
[0005]
As shown in FIG. 5, the preprocessing circuits 4R, 4G, and 4B are formed by substantially the same circuit, and input the imaging signals SR, SG, and SB to the correlated double sampling circuits (CDS) 5R, 5G, and 5B. Here, the correlated double sampling circuits 5R, 5G, and 5B sequentially sample and subtract the imaging signals SR, SG, and SB, respectively, using a correlated double sampling method, and each of the imaging signals SR, SG, and SB is red, The color signals are converted into blue and green color signals R, G, and B.
[0006]
Further, the preprocessing circuits 4R, 4G, and 4B trap the specified frequency bands for the red, blue, and green color signals R, G, and B in the subsequent trap circuits 6R, 6G, and 6B, and thereby each color signal R, The drive pulse components of the CCD solid-state imaging devices 3R, 3G, and 3B mixed with G and B are removed.
[0007]
Further, the preprocessing circuits 4R, 4G, and 4B amplify the red, blue, and green color signals R, G, and B with predetermined gains in the subsequent amplification circuits 7R, 7G, and 7B, respectively. At this time, each of the amplifier circuits 7R, 7G, and 7B is controlled by the system control circuit 8 (FIG. 4) to change the gain, whereby the television camera 1 sets the signal levels of the color signals R, G, and B to the specified values. Are output to the analog signal processing circuits 9R, 9G, and 9B.
[0008]
Each of the analog signal processing circuits 9R, 9G, and 9B corrects the signal level of the color signals R, G, and B with a correction signal that is synchronized with the horizontal synchronization signal and the vertical synchronization signal, respectively, and thereby the color signals R, G, and B are corrected. Then, processing such as shading correction is executed, and amplified with a specified gain and output. When outputting the color signals R, G, and B, the analog signal processing circuits 9R, 9G, and 9B clamp the color signals R, G, and B by the built-in clamp circuits 10R, 10G, and 10B. R, G, B black levels are set to specified signal levels.
[0009]
Subsequent low-pass filter circuits (LPF) 11R, 11G, and 11B limit the color signals R, G, and B, respectively, and output the analog signals to analog-to-digital conversion circuits (A / D) 12R, 12G, and 12B. The 12R, 12G, and 12B convert the color signals R, G, and B into digital color signals DR, DG, and DB by analog-digital conversion processing and output them.
[0010]
As a result, in the television camera 1, in the preprocessing circuits 4R, 4G, and 4B from the correlated double sampling circuits 5R, 5G, and 5B to the analog-digital conversion circuits 12R, 12G, and 12B, the imaging results are converted into color signals R, G, and B. The color signals R, G, and B are converted into digital signals by performing predetermined processing in advance.
[0011]
The detector 13 (FIG. 4) detects the signal levels of the digital color signals DR, DG, and DB, and outputs the detection result S1 to the system control circuit 8. The system control circuit 8 is formed of a microcomputer that controls the operation of the entire camera-integrated video tape recorder, and detects the brightness of the subject from the detection result S1 output from the detector 13. Further, the system control circuit 8 outputs a lens aperture position control signal IC based on the brightness detection result, and controls the aperture of the lens 2 so as to maintain the brightness of the subject at a constant value.
[0012]
At the time of the aperture control, the system control circuit 8 outputs a lens aperture position control signal IC with reference to the lens aperture position signal IP output from the lens 2. Thereby, in the television camera 1, an auto iris circuit for controlling the aperture of the lens 2 is formed by the system control circuit 8 and the detector 13.
[0013]
The digital signal processing circuits 14R, 14G, and 14B respectively perform linear matrix processing, detail signal addition processing, and pedestal addition processing on the digital color signals DR, DG, and DB output from the preprocessing circuits 4R, 4G, and 4B, respectively. , Gamma correction processing, knee processing, white clip processing, and the like are executed. Thus, the television camera 1 executes various processes required for the color signals R, G, and B when the digital signal processing circuits 14R, 14G, and 14B synthesize the video signal SV, respectively. It is made like that.
[0014]
The encoder 16 is formed by an arithmetic circuit that adds and subtracts the digital color signals DR, DG, and DB by weighting, and generates a luminance signal and a color difference signal that are digital signals from the digital color signals DR, DG, and DB. The digital / analog conversion circuit (D / A) 17 converts the digital signal output from the encoder 16 into an analog signal, and the low-pass filter 18 limits the band of the analog signal to remove the noise component and output it. To do. As a result, the television camera 1 outputs, for example, an NTSC video signal SV in the form of a luminance signal and a color difference signal.
[0015]
When the video signal SV is output in this way, the television camera 1 detects the signal levels of the digital color signals DR, DG, DB at the detector 13 as shown in FIG. 6, and this signal level detection result S1. Based on the above, the aperture is controlled by the system control circuit 8, whereby the brightness of the subject is held at a constant value. The system control circuit 8 controls the aperture based on the signal level detection result S1 by executing a predetermined processing procedure at a constant cycle. In FIG. 6, the system control circuit 8 is represented by a functional block.
[0016]
That is, the detector 13 inputs the digital color signals DR, DG, DB to the luminance signal conversion circuit 13A, and converts the digital color signals DR, DG, DB into digital luminance signals. Further, the detector 13 provides the digital luminance signal to the integrating circuit 13C via the gate circuit 13B operated by the region designation gate pulse PAR, and integrates the digital luminance signal.
[0017]
Here, in this type of television camera 1, an area to be controlled by the auto iris circuit can be set by the operation of a cameraman or by remote control, and the area designating gate pulse PAR is a predetermined pulse generator. Thus, it is generated in synchronism with the digital color signals DR, DG, and DB so that the logic level rises in the region set by this photographer.
[0018]
As a result, the detector 13 integrates the digital luminance signal for the area designated by the cameraman or the like in the integration circuit 13C, and outputs the integration result to the system control circuit 8 as the signal level detection result S1. Further, the detector 13 counts the period in which the logic level of the region designation gate pulse PAR rises in the area detection circuit 13D, thereby detecting the area of this region, and outputs the area detection result SAR to the system control circuit 8.
[0019]
In the average value calculation processing circuit 8A, the system control circuit 8 divides the signal level detection result S1 by the area detection result SAR, thereby detecting the average value level S2 of the luminance signal for the area set by the cameraman, etc. The average value level S2 is output as the brightness of the subject. Further, the system control circuit 8 generates a lens aperture position control signal IC with reference to the lens aperture position signal IP so that the average value level S2 coincides with the reference level REF1 in the control signal output circuit 8B. An aperture position control signal IC is output to the lens 2.
[0020]
Here, this type of lens 2 detects a variable amount of the aperture with a potentiometer, and outputs the detection result as a lens aperture position signal IP. At this time, in the built-in circuit, the lens 2 varies the diaphragm based on the comparison result between the lens diaphragm position signal IP and the lens diaphragm position control signal IC, thereby forming a feedback loop in the built-in circuit to control the diaphragm. .
[0021]
The lens 2 is formed so that the gain of the feedback loop can be set by a gain switching signal GS (FIG. 4) output from the system control circuit 8. In the television camera 1, for example, when imaging is performed in an aperture priority state. In this case, the gain is set to the maximum and a necessary lens aperture position control signal IC is output to stop the operation of the auto iris circuit. When the auto iris circuit is operated, the television camera 1 sets the gain to a value adjusted by the cameraman or the like, and the cameraman or the like adjusts the gain every time the lens 2 is replaced.
[0022]
Thereby, the system control circuit 8 uses the lens aperture position control signal IC so that the aperture of the lens 2 is adjusted so that the brightness of the subject specified by the digital color signals DR, DG, and DB becomes the brightness determined by the reference level REF1. Has been made to control.
[0023]
The system control circuit 8 actually executes the processing of the functional blocks described above with reference to FIG. 6 by executing the processing procedure shown in FIG. That is, the system control circuit 8 proceeds from step SP1 to step SP2, where it is determined whether or not the integration operation for one field in the detector 13 has been completed, and if a negative result is obtained, step SP2 is repeated. As a result, the system control circuit 8 waits for the completion of the integration operation for one field in the detector 13, and when this integration operation is completed, the system control circuit 8 moves to step SP3 and inputs the signal level detection result S1 and the area detection result SAR as integration results. To do.
[0024]
Subsequently, in step SP4, the system control circuit 8 divides the signal level detection result S1 by the area detection result SAR, and detects the average value level S2 of the luminance signal for the region set by the cameraman or the like. Further, in the subsequent step SP5, the system control circuit 8 subtracts the reference level REF1 from the average value level S2 to generate a lens aperture position control signal IC. Further, the system control circuit 8 updates the contents of the output buffer with the generated lens aperture position control signal IC in the subsequent step SP6, and then returns to step SP2.
[0025]
As a result, the system control circuit 8 outputs the lens aperture position control signal IC recorded in the output buffer to the lens 2, and the brightness of the subject defined by the digital color signals DR, DG, DB is determined by the reference level REF1. The aperture of the lens 2 is controlled so that it becomes the same.
[0026]
[Problems to be solved by the invention]
By the way, in this type of television camera 1, as described above, the aperture of the lens 2 is controlled so that the average value level of the luminance signal matches the reference level REF1 in the region set by the cameraman or the like. That is, in the conventional television camera 1, the brightness of this area is assumed to be the brightness of the subject, and the aperture is controlled so that this brightness becomes a constant value.
[0027]
For this reason, in the conventional television camera 1, when the area other than the subject itself is included in the background of the subject, the aperture is controlled so that the overall brightness of the subject and the background is constant. After all, in such a case, there is a problem that it is difficult to maintain the brightness of the subject itself at a constant value.
[0028]
That is, in such a case, even when only the brightness of the background changes, the aperture amount of the diaphragm changes, and the brightness of the subject changes in the imaging result after all. Conversely, if only the brightness of the subject itself changes, the change in the brightness of the entire area is detected to be small. In this case, the aperture can be made small and variable with respect to the change in the brightness of the subject itself. In this case as well, the brightness of the subject changes in the imaging result.
[0029]
Incidentally, there is a method of controlling the aperture so that the brightness of the entire screen becomes a constant level instead of this type of region, but in this case as well, the above-mentioned problem occurs due to simultaneous imaging of the background.
[0030]
The present invention has been made in consideration of the above points, and an object of the present invention is to propose an imaging apparatus capable of maintaining the brightness of a subject itself at a constant value.
[0031]
[Means for Solving the Problems]
To solve this problemClaim 1In the invention, an imaging unit that outputs an imaging result, an optical system that forms an image of a subject on an imaging surface of the imaging unit, and an imaging result that satisfies a specified condition are selected from the imaging result, and the selected Control means for correcting the signal level of the imaging result output from the previous imaging means based on the signal level of the imaging result, and the imaging result satisfying this prescribed condition is the imaging result of the prescribed hueAnd thenInThe control means detects the area based on the selected imaging result, and holds the correction amount for correcting the signal level of the imaging result at the immediately preceding value when the area decreases below a specified value.Like that.
[0032]
AlsoIn invention of Claim 2, in the structure of Claim 1,In addition to the specified hue, the imaging result satisfying the previously specified condition is made to be an imaging result having a specified saturation level.
[0033]
furtherIn invention of Claim 3, in the structure of Claim 1 or Claim 3,The previous control means controls the aperture of the optical system to correct the signal level of the imaging result so that the signal level of the imaging result is held at a specified value.
[0035]
[Action]
When an imaging result that satisfies a specified condition is selected from the imaging results and the signal level of the imaging result output from the previous imaging unit is corrected based on the signal level of the selected imaging result, If the imaging result is selected, the subject can be determined from the imaging result using the color of the subject as a clue, and the signal level of the imaging result can be corrected so that the brightness of the subject becomes a prescribed brightness.In addition, when the area based on the selected imaging result is detected and this area decreases below the specified value, if the correction amount for correcting the signal level of the previous imaging result is held at the previous value, the subject becomes smaller on the imaging screen. In such a case, malfunction can be effectively avoided.
[0036]
At this time, if an imaging result is selected in consideration of saturation as well as hue, the subject can be reliably identified even for a subject whose color is close to colorless.
[0037]
Further, by controlling the aperture of the optical system so that the signal level of the imaging result is corrected so that the signal level of the imaging result is held at a specified value, an auto iris function by controlling the aperture can be realized.
[0038]
In addition, when the area based on the selected imaging result is detected and this area decreases to a predetermined value or less, if the correction amount for correcting the signal level of the previous imaging result is held at the immediately preceding value, the subject is displayed on the imaging screen. In such a case, the malfunction can be effectively avoided.
[0039]
【Example】
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.
[0040]
In FIG. 2, reference numeral 30 denotes a television camera according to an embodiment of the present invention as a whole, and the video signal SV output from the television camera 30 is recorded by a video tape recorder housed in the same casing. Here, in this embodiment, the same components as those of the conventional television camera 1 described above are denoted by the same reference numerals, and redundant description is omitted.
[0041]
In this embodiment, the television camera 30 is controlled by the system control circuit 31 in place of the system control circuit 8 (FIG. 4), and the signal level detection result S3 necessary for controlling the diaphragm by the detector 32. And the area detection result SAR1 is detected.
[0042]
Here, as shown in FIG. 1, the detector 32 inputs the digital color signals DR, DG, DB to the luminance signal conversion circuit 32A and the hue detection comparison circuit 32E, and in this luminance signal conversion circuit 32A, the digital color signals DR, A digital luminance signal is generated by weighted addition of DG and DB.
[0043]
The hue detection / comparison circuit 32E detects the division results representing the hues of the digital color signals DR, DG, and DB by dividing the red and blue digital color signals DR and DB by the green digital color signal DG, respectively. Further, the hue detection / comparison circuit 32E, based on these division results, the area designation gate pulse PAR1 whose logic level rises when the hues of the digital color signals DR, DG, DB are hues within a predetermined range designated by the hue designation information DS. Is generated.
[0044]
Here, in the television camera 30, an auto iris target (that is, a target for maintaining the brightness at a constant value) can be designated by hue by operating an operation element arranged on the operation panel or by remote control. Has been made. The system control circuit 31 is formed so as to accept this designation based on the central value of the hue and the size from the central value. The system control circuit 31 specifies the target hue range from the designation, and sets the range based on the hue designation information DS. It is set in the hue detection comparison circuit 32E.
[0045]
As a result, the detector 32 generates a region designation gate pulse PAR1 corresponding to the conventional region designation gate pulse PAR (FIG. 6) in the hue detection / comparison circuit 32E in accordance with the hue designated by the cameraman or the like. Yes. The television camera 30 has a viewfinder for monitoring the imaging result, and adds the region designation gate pulse PAR1 to the luminance signal output to the viewfinder in response to an operation of a cameraman or the like. . As a result, the television camera 30 can easily confirm the target of the auto iris specified by the designated hue on the viewfinder.
[0046]
The integration circuit 32C inputs the digital luminance signal output from the luminance signal conversion circuit 32A via the gate circuit 32B operated by the region designation gate pulse PAR1, and thereby the hue in the range designated by the hue designation information DS. , The digital luminance signal is integrated, and the integration result is output as the signal level detection result S3.
[0047]
The area detection circuit 32D detects the area of this region by counting the period during which the logic level of the region designation gate pulse PAR1 rises, and outputs the area detection result SAR1.
[0048]
In the average value calculation processing circuit 31A, the system control circuit 31 divides the signal level detection result S3 by the area detection result SAR1, thereby detecting the average value level S4 of the digital luminance signal for the hue specified by the cameraman or the like. . As a result, the television camera 30 discriminates the subject based on the hue and detects the brightness of the subject.
[0049]
As a result, the television camera 30 can correctly detect the brightness of the subject itself even when the subject is arranged on a part of the screen and even when the subject is arranged at a corner of the screen. it can. Even when the subject moves on the screen, the movement of the subject can be tracked and the brightness of the subject can be detected correctly. Therefore, the brightness of the subject itself can be kept constant when the aperture is controlled based on the brightness of the subject thus detected.
[0050]
Thereby, the system control circuit 31 generates the lens aperture position control signal IC with reference to the lens aperture position signal IP so that the average value level S4 coincides with the reference level REF1 in the subsequent control signal output circuit 31B. This lens aperture position control signal IC is output to the lens 2. Thus, the television camera 30 detects the aperture control target based on the hue, and controls the aperture so that the aperture control target has a specified brightness.
[0051]
By the way, in an actual shooting site, a subject may be shot small on an imaging screen. In such a case, when the subject is detected based on the hue as described above, the brightness of the subject cannot be detected correctly because the area for detecting the average value level of the digital luminance signal becomes small.
[0052]
Also, at the shooting site, the lighting may change suddenly. In such a case, if the subject is detected based on the hue as described above, it is difficult to correctly determine the subject due to the sudden change in the shooting situation. In this case, it becomes difficult to detect the average value level of the digital luminance signal.
[0053]
Further, at the shooting site, there is a case where the moving subject is photographed with a fixed background. In this case, after the subject is removed from the screen, the average value level that is the reference for aperture control cannot be detected.
[0054]
Therefore, the system control circuit 31 determines in the control signal output circuit 31B whether or not the area of the subject is equal to or less than a specified value based on the area detection result SAR1, and when this area falls below the specified value, the lens aperture position control signal IC Is held at the previous value. As a result, the television camera 30 effectively avoids an uncontrollable situation in aperture control even when the brightness of the subject cannot be detected correctly depending on the hue.
[0055]
In practice, the system control circuit 31 executes the processing of the functional blocks described above with reference to FIG. 1 by executing the processing procedure shown in FIG. That is, the system control circuit 31 proceeds from step SP11 to step SP12, where it determines whether or not the integration operation for one field in the detector 32 has been completed. If a negative result is obtained here, step SP12 is repeated. As a result, the system control circuit 31 waits for the completion of the integration operation for one field in the detector 32. When this integration operation is completed, the system control circuit 31 proceeds to step SP33 and inputs the signal level detection result S3 as the integration result together with the area detection result SAR1. To do.
[0056]
Subsequently, in step SP14, the system control circuit 31 divides the signal level detection result S3 by the area detection result SAR1, and detects the average value level S4 of the luminance signal for the hue specified by the cameraman or the like. Further, in the subsequent step SP15, the system control circuit 31 determines whether or not the area of the subject is equal to or greater than a specified value based on the area detection result SAR1, and when an affirmative result is obtained, the system control circuit 31 proceeds to step SP16.
[0057]
Here, the system control circuit 31 subtracts the reference level REF1 from the average value level S4 to generate the lens aperture position control signal IC. Further, in the subsequent step SP17, the system control circuit 31 updates the contents of the output buffer with the generated lens aperture position control signal IC, and then returns to step SP11.
[0058]
As a result, the system control circuit 31 outputs the lens aperture position control signal IC recorded in the output buffer to the lens 2 so that the brightness of the subject specified by the hue becomes the brightness determined by the reference level REF1. 2 aperture is controlled.
[0059]
On the other hand, when the area of the subject is smaller than the specified value, the system control circuit 31 obtains a negative result in step SP15, and proceeds to step SP18. Here, the system control circuit 31 holds the lens aperture position control signal IC recorded in the output buffer as it is, and returns to step SP12. As a result, when the brightness of the subject cannot be detected correctly depending on the hue, the system control circuit 31 continuously outputs the lens aperture position control signal IC output immediately before, effectively avoiding an uncontrollable situation.
[0060]
In the configuration described above, the incident light of the lens 2 is condensed on the imaging surfaces of the CCD solid-state imaging devices 3R, 3G, and 3B after the amount of light is limited by the aperture of the lens 2, and is photoelectrically converted here to the imaging signal SR. , SG and SB are generated. The imaging signals SR, SG, and SB are converted into red, blue, and green color signals R, G, and B in the preprocessing circuits 4R, 4G, and 4B, and then subjected to processing such as clamping, so that the digital color signal DR , DG, DB.
[0061]
The digital color signals DR, DG, DB are subjected to digital signal processing such as linear matrix processing in the digital signal processing circuits 14R, 14G, 14B, and then converted into luminance signals and color difference signals by the encoder 16, and the luminance signals The color difference signal is converted from digital to analog into a video signal SV.
[0062]
Further, the digital color signals DR, DG, DB are input to the detector 32, converted into a digital luminance signal by the luminance signal conversion circuit 32A, and the hue is detected by the hue detection comparison circuit 32E. This hue detection result is determined by the hue detection comparison circuit 32E as to whether or not there is a hue within a predetermined range designated by the hue designation information DS, whereby the hues of the digital color signals DR, DG, DB are within this predetermined range. When the hue is within the range, the region designation gate pulse PAR1 in which the logic level rises is generated.
[0063]
As a result, the digital color signals DR, DG, and DB are detected by the detector 32 based on the hue. The digital luminance signal is output to the integration circuit 32C via the gate circuit 32B operated by the region designation gate pulse PAR1, and is integrated there to detect the signal level detection result S3. In the area detection circuit 32D, the area of the subject is detected by counting the period during which the logic level of the region designation gate pulse PAR1 rises.
[0064]
As a result, the signal level detection result S3 is divided by the area detection result SAR1 in the system control circuit 31, and the brightness of the subject determined by the hue is detected, so that the detection result S4 becomes the reference level REF1. Aperture is controlled. When the area is less than or equal to the specified value, the diaphragm is held at the previous aperture value, thereby effectively avoiding an uncontrollable state.
[0065]
According to the above configuration, the brightness of the subject can be correctly detected by determining the subject from the imaging result based on the hue and detecting the brightness of the subject. The diaphragm can be controlled so as to keep the thickness constant.
[0066]
In addition, when the area of the object detected with reference to the hue is smaller than the specified value, the aperture is kept at the previous aperture value, so that the uncontrollable state is effective when the aperture is controlled based on the hue. Can be avoided.
[0067]
In the above-described embodiment, the case where the subject is determined based on the hue has been described. However, the present invention is not limited to this, and the subject may be determined based on the saturation in addition to the hue. In other words, for most imaging targets, the subject can be correctly determined on the basis of the hue as described above. However, in rare cases, an object that is nearly colorless may be selected as a subject. When such a nearly colorless object is imaged, it may be difficult to discriminate the subject with only the hue.
[0068]
On the other hand, if the subject is identified by the angle from the reference axis (that is, hue) and the distance from the origin (that is, saturation) when the imaging result is expressed in polar coordinate format, In addition, the subject can be discriminated reliably, so that the aperture can be correctly controlled even in such an extremely rare case.
[0069]
In the above-described embodiments, the case where the brightness of the subject is detected based on the hue and the aperture is controlled based on the detection result has been described. However, the present invention is not limited to this, and for example, in a simple imaging device or the like In this case, the brightness of the subject may be maintained at a prescribed brightness by controlling the shutter speed instead of the aperture.
[0070]
Furthermore, in the above-described embodiment, the case where the detector detects the brightness of the subject after generating the luminance signal from the digital color signal in the detector has been described. However, the present invention is not limited to this, and the luminance signal output from the encoder is described. The present invention can be widely applied to the case where the brightness of the subject is detected from the imaging result, such as the case where the brightness of the subject is detected from.
[0071]
In the above-described embodiments, the case where the detector discriminates the subject based on the hue from the digital color signal has been described. However, the present invention is not limited to this, and the hue is determined based on the color difference signal output from the encoder. The present invention can be widely applied to discriminating a subject based on hue based on various types of imaging results, such as discriminating a subject using a complementary color signal, and discriminating a subject based on hue based on a complementary color signal. .
[0072]
Further, in the above-described embodiment, the case where the diaphragm is controlled by executing a series of processing procedures by the system control circuit has been described. However, the present invention is not limited to this, and the case where the auto iris circuit is formed by a dedicated analog circuit, etc. Can also be widely applied.
[0073]
Further, in the above-described embodiments, the case where the present invention is applied to a television camera in which the signal processing circuit is formed by a digital signal processing circuit has been described. However, the present invention is not limited to this, and the signal processing circuit is an analog circuit. The present invention can be widely applied to the configuration.
[0074]
Further, in the above-described embodiment, the case where the present invention is applied to a television camera of a camera-integrated video tape recorder has been described, but the present invention is not limited thereto, and a general television camera that outputs a video signal, etc. The present invention can be widely applied to various imaging devices.
[0075]
【The invention's effect】
As described above, according to the present invention, the subject is determined based on the hue.However, if the area of this hue portion becomes smaller, it will be held at the previous correction amount.By doing so, it is possible to correctly detect and control the brightness of the subject itself, and thereby maintain the brightness of the subject itself at a constant value.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an auto iris circuit of a television camera according to an embodiment of the present invention.
2 is a block diagram showing an overall configuration of the television camera of FIG. 1. FIG.
FIG. 3 is a flowchart for explaining the operation of the system control circuit of FIG. 1;
FIG. 4 is a block diagram showing a conventional television camera.
FIG. 5 is a block diagram showing the preprocessing circuit of FIG. 4;
6 is a block diagram showing an auto iris circuit of the television camera of FIG. 4. FIG.
7 is a flowchart for explaining the operation of the system control circuit of FIG. 5;
[Explanation of symbols]
1,30 Television camera
2 Lens
3R, 3G, 3B CCD solid-state image sensor
4R, 4G, 4B pre-processing circuit
8, 31 System control circuit
8A, 31A Average value calculation processing circuit
8F, 31F Change amount detection circuit
9R, 9G, 9B Analog signal processing circuit
12R, 12G, 12B Analog to digital converter
13, 32 detector
13A, 32A luminance signal conversion circuit
13C, 32C integration circuit
13D, 32D area detection circuit
14R, 14G, 14B Digital signal processing circuit
32E Hue detection comparison circuit

Claims (3)

Imaging means for outputting imaging results;
An optical system that forms an image of a subject on the imaging surface of the imaging means;
A control unit that selects an imaging result that satisfies a specified condition from the imaging result, and that corrects the signal level of the imaging result output from the imaging unit based on the signal level of the selected imaging result;
The imaging result that satisfies the specified conditions is
It is the imaging result of the specified hue,
The control means includes
An area of the selected imaging result is detected, and when the area decreases to a predetermined value or less, a correction amount for correcting the signal level of the imaging result is held at the immediately preceding value. apparatus. The imaging result that satisfies the specified conditions is
The imaging apparatus according to claim 1, wherein the imaging device includes an imaging result having a specified saturation in addition to the specified hue. The control means includes
The signal level of the imaging result is corrected so that the signal level of the imaging result is held at a specified value by controlling a diaphragm of the optical system. Imaging device.

Images