JP2004207795A - Imaging apparatus and its exposure control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging apparatus and its exposure control method which performs a suitable photometric operation even for photographing a photographer itself and a more satisfactory photographing operation. <P>SOLUTION: The imaging apparatus A has a lens 3 for catching the image of a subject, an iris 31, a CCD (charge-coupled device) 5 for transducing optical signals into electric signals, a CDS/AGC circuit 7 for amplifying and sampling the electric signals from the CCD 5, an AD converter 11 for sampling the electric signals from the CCD 5 into digital signals, a camera signal processing part 15 for processing a digital-converted image, even- and odd-field memories 17, 21, a vertical-inversion memory reading circuit 23 for vertically inverting an image using signals stored in the memories 17, 21, a vertically inverting circuit 25 including something, a recording circuit 27 for recording images, and a vertical-inversion detector 33 for detecting whether or not an imaging part is vertically inverted. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention is a video camera with a monitor having a monitor unit and a camera unit, wherein the camera unit includes an imaging unit, and a recording / reproducing and grip unit (recording unit) rotatable relative to the imaging unit. The present invention relates to an exposure control technique for an imaging device configured by:
[0002]
[Prior art]
In a video camera with a liquid crystal monitor (camera-integrated VTR), the liquid crystal monitor and the camera are mounted so as to be relatively rotatable by a rotating mechanism. Further, there is an image pickup apparatus of a type in which a camera section includes an image pickup section and a recording / reproducing and grip section rotatable relative to the image pickup section. This type of imaging device is referred to herein as a rotary imaging device.
[0003]
Hereinafter, the outline of the configuration of the rotary imaging device will be described with reference to FIG. FIG. 6A is a front view of a rotary imaging device (video camera), and FIG. 6B is a rear view (view from the photographer side) of the rotary imaging device. As shown in FIGS. 6A and 6B, the rotary imaging device 100 is rotatable by a swinging member 123 with respect to the main body having the recording / reproducing unit 101 and the imaging unit 102. (For example, a monitor having a liquid crystal display screen 104) 103 attached to the camera. The imaging unit 102 includes a lens 105 for photographing a subject and a viewfinder 106.
[0004]
The monitor rotating type video camera 100 shown in FIGS. 6A and 6B turns the monitor unit 103 having the LCD display screen 104 so that the lens 105 is directed to the photographer himself and monitors the image of the photographer himself. It is possible to shoot while confirming by the unit 103. In this case, by rotating the monitor unit 103 without turning the body units 101 and 102 upside down in order to maintain the lens 105 in the upright position, it is possible to capture an image having a correct positional relationship in the vertical direction. it can.
[0005]
On the other hand, in a camera having an automatic exposure (so-called AE) function, photometry is required to determine exposure conditions. 2. Description of the Related Art In an imaging apparatus that includes a solid-state imaging device (CCD or the like) and obtains a video signal representing a subject image, a method of obtaining a photometric value by dividing a video signal output from the solid-state imaging device into an appropriate photometric region and integrating the photometric region. Is considered. By electrically processing video signals obtained from the solid-state image sensor, variations such as average photometry, partial photometry, and split photometry are possible, and exposure conditions can be set for various shooting environments. It is.
[0006]
For example, partial photometry is performed based on a video signal obtained from a substantially central part and a lower part of a photographing region in which a main subject is relatively likely to be present. Such partial photometry has the advantage that the main subject can always be properly exposed.
[0007]
FIG. 3 shows a composition in which the upper part is empty and the person is in the lower part, and it can be seen that there is important information in the central part and the lower part. As described above, many subjects have important information in the central part and the lower part. By performing the photometry with emphasis on the center and the lower part rather than the average photometry of the entire screen, important subjects can be measured. And appropriate exposure is possible.
[0008]
[Patent Document 1]
JP-A-6-98210
[Problems to be solved by the invention]
However, in the rotary imaging apparatus 100 shown in FIG. 6, in order to hold the lens 105 in the normal position, it is necessary to change the hand holding the grip and the like. In order to place importance on ease of use, it is preferable that the grip is held as it is. As a configuration for this, as shown in FIG. 7, the main body is constituted by an imaging unit 101 and a recording / reproducing unit 102, and the imaging unit 101 and the recording / reproducing unit 102 are connected to each other by a connecting member 121 rotatably coupled. Allows relative rotation. With such a configuration, the lens unit 105 attached to the imaging unit 102 is directed to the photographer himself by relatively rotating the imaging unit 101 and the recording / reproducing unit 102 that constitute the main body unit. Allows you to shoot yourself. In this case, the monitor unit 103 is rotated so that the photographer himself can see and confirm the display screen 104.
[0010]
In the rotating imaging apparatus 100 capable of face-to-face imaging as described above, when imaging the photographer himself, the imaging unit 101 is turned upside down as shown in FIG. In the case of face-to-face shooting in which the imaging unit 101 is reversed (vertical inversion), the video recorded in the recording unit 102 is also reversed (vertical inversion), which is unsightly and has a problem with exposure correction. .
An object of the present invention is to provide an imaging apparatus capable of performing appropriate photometry (exposure correction) even in face-to-face shooting and capable of performing better shooting, and an exposure control method thereof.
[0011]
[Means for Solving the Problems]
According to one aspect of the present invention, there is provided an imaging apparatus including a recording unit and an imaging unit provided rotatably with respect to the recording unit, wherein a first electric signal output from the imaging unit is A signal processing unit for processing, a vertical inversion detector for detecting the vertical inversion of the imaging unit, and an image generated by an output signal from the signal processing unit based on a detection result of the vertical inversion by the vertical inversion detector There is provided an imaging apparatus having an upside-down inversion circuit that performs processing to display data upside down.
According to the above-described imaging apparatus, when the image capturing unit detects upside-down inversion, the image data processing is performed so as to be upside-down. Therefore, even when the imaging unit is rotated, it is possible to output image data in a normal position even when the imaging unit is rotated. it can.
[0012]
According to an imaging apparatus according to another aspect of the present invention, a recording unit; provided to be relatively rotatable with respect to the recording unit, and provided between an imaging lens, an imaging device, and the imaging lens and the imaging device. And an iris driven by an iris drive circuit. An imaging device comprising: an upside-down inversion detector for detecting upside-down inversion of the imaging unit; and an iris output from the imaging unit. A signal processing unit for processing the first electrical signal, and a vertical inversion for performing a process for vertically inverting and displaying image data generated based on the first electrical signal based on a detection result of the vertical inversion detector A circuit, a divided photometric detection circuit that divides the image data into a plurality of photometric areas and performs photometry, based on a detection result of the upside-down inversion by the upside-down inversion detector, Calculating a weighting of the photometric per light area, an imaging device and a control unit for controlling the iris driving circuit based on the weight degree is provided.
According to the above-described imaging apparatus, even if the imaging unit is turned upside down, weighting can be performed according to a subject important for auto iris control, so that appropriate exposure can be performed even in reverse imaging.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
In this specification, a subject generally refers to an important part such as a person at the center of an image, and is used as a term corresponding to a background existing in a peripheral part.
An imaging apparatus and an exposure control method thereof according to the present invention will be described with reference to the drawings. The inventor has considered the cause of the problem of exposure correction in the case of face-to-face photographing in which the imaging unit is reversed (vertically inverted) as follows. As described above, FIG. 3 is a diagram illustrating an example of a composition in a general video at the time of normal shooting. FIG. 4 is a diagram showing a composition of a video in the case of face-to-face shooting, and is a diagram showing a composition of a case where a subject corresponding to FIG. 3 is shot. As can be seen from a comparison between FIG. 3 and FIG. 4, when the exposure correction is performed based on the upside-down image, the image in which the person and the sky are reversed and the exposure correction for an important subject such as a person is not correctly performed. Is likely to be That is, as shown in FIG. 4, the image taken is also upside down. In this case, if photometry is performed in the same manner as before, the sky and the person are turned upside down, so the photometer may measure the sky at the time of exposure and do not meter the person. Metering is not possible.
[0014]
In consideration of the above points, an imaging technique according to the first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a functional block diagram illustrating a configuration example of an imaging device according to the present embodiment. The basic external configuration is the same as that of the imaging device described with reference to FIGS. 6 and 7, and will be described below with reference to FIGS. 6 and 7 as appropriate.
[0015]
As shown in FIG. 1, a rotary imaging apparatus A according to the present embodiment includes a lens 3 for capturing an image of a subject, an iris 31, a CCD (solid-state imaging device) 5 for converting an optical signal into an electric signal, and a CCD 5 CDS / AGC circuit 7 for amplifying and sampling the electric signal output from the CCD, an AD converter (ADC) 11 for sampling the electric signal output from the CCD as a digital signal, and camera signal processing for processing the digitized video. A memory 15 for an even field (hereinafter, referred to as an “even field memory”) 17 and a memory for an odd field (hereinafter, referred to as an “even field memory”) 21; A vertically inverted memory readout circuit 23 for vertically inverting and reading an image using a stored signal. 5, a recording circuit 27 for recording the output from the vertical inversion circuit 25 as video data, and a vertical inversion detector 33 for detecting whether or not the imaging unit 101 (FIG. 6) is vertically inverted. I have.
[0016]
In the imaging device A, the optical signal captured by the lens 3 is incident on the CCD 5 and converted into an electric signal when the iris 31 is open. The electric signal is converted into a digital signal by the CDS / AGC circuit 7 for performing amplification and sampling and the AD converter 15 for digitally sampling the CCD signal, and is input to the camera signal processing unit 15. In this state, the video signal remains the reverse, and is not a normal video. This signal is converted to normal video data whose upper and lower sides are correct by an upper and lower inverting circuit 25 including an even field memory 17 and an even field memory 21 and an upper and lower inverted memory read circuit 23.
[0017]
The upside down circuit 25 operates, for example, as described below. First, in order to invert both the horizontal direction and the vertical direction, upside-down images are stored in the memories 17 and 21 as they are. Next, the address is counted down and read, and an upside-down image is output. In the case of the imaging device according to the present embodiment, the video of the even field is stored in the even field memory 17. Next, the video of the odd field is stored in the odd field memory 21. Meanwhile, the image displayed on the basis of the video signal is inverted upside down and output from the even field memory 17 if it is read out from the even field memory 17 at the address opposite to that at the time of writing. can do. By performing writing and inversion reading to the even field memory 17 and the odd field memory 21 for each field, a continuous video can be inverted upside down and output. Whether the imaging unit 101 is upside down is detected by the upside down detector 33. After detecting whether or not the imaging unit 101 has been turned upside down by the upside-down inversion detector 33, a signal indicating that the imaging unit 101 is upside-down is output to the upside-down inverted memory readout circuit 23. When the camera is not upside down, signals may be read out in the order of addresses by a normal writing operation.
[0018]
Next, an imaging device according to a second embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a functional block diagram illustrating a configuration example of the imaging device according to the present embodiment. The external configuration is the same as the configuration shown in FIGS.
The rotary imaging device B according to the present embodiment includes a lens 53 for capturing an image of a subject, a CCD (solid-state imaging device) 55 for converting an optical signal into an electric signal, and a CDS for amplifying and sampling a signal transferred from the CCD 55. / AGC circuit 57, an AD converter (ADC) 61 for converting a CCD signal into a digital signal, a camera signal processing unit 65 for processing a digitized video, and a microcomputer 73 for detecting upside down of the imaging unit 101 and detecting the upside down of the imaging unit 101, which will be described later. A vertical inversion circuit 81 that can invert a signal from the camera signal processing unit 65 and output the inverted signal, a diaphragm (iris) 83 that controls an optical signal from the lens 53, An iris drive circuit 75 for controlling the aperture of the iris 83; a lens drive circuit 77 for driving the lens 53; Composed photometric / distance measuring circuit 71 for performing photometric / distance measurement based on the signal et detected, the microcomputer 73 capable of controlling the iris driving circuit 75 and a lens driving circuit 77, it contains.
[0019]
The operation of the imaging apparatus B having the above configuration, particularly, the auto iris control and the auto focus control will be described below. Reference is also made to FIGS. Auto iris control generally uses a combination of a dual pattern photometry method and a peak sensing method. The dual pattern photometry method is a method of calculating a weighted average value with emphasis on a central portion and a lower portion from a video signal, comparing the weighted average value with a reference luminance, and feeding back to the iris to control the iris. In many cases, the subject exists at the center and the lower part of the screen.According to this method, the brightness of the subject is controlled to match the reference brightness, and in the case of weak backlight, the exposure is appropriately controlled. You.
[0020]
The peak sensing method is a method of obtaining the maximum value of a video signal and performing feedback control on the iris so that the maximum value matches the reference luminance. According to this method, since the maximum luminance in the image does not saturate, the overexposure phenomenon can be prevented even under over-direct light conditions. However, actually, when the operation is performed based only on the peak sensing method, an image may be underexposed. Therefore, by combining the peak sensing method and the above-described dual pattern photometry, the influence of peak sensing (insufficient image exposure) is reduced.
[0021]
On the other hand, as for the auto focus control, a video AF method is generally adopted. In the video AF method, the lens 53 is controlled to focus on the basis of the magnitude of a high-frequency component included in a video signal obtained through a lens 53 and a CCD (image pickup device) 55. When the focus lens is moved forward and backward, the magnitude of the high-frequency component included in the video signal draws a mountain shape having a peak at the in-focus position. The basic principle of video AF is to detect the direction of this mountain and climb up the mountain to focus on the top.
[0022]
In the image pickup apparatus employing the video AF method, when the image pickup unit 101 is not turned upside down, a weighted average with emphasis on the center and the lower part is obtained as shown in FIG. And the maximum luminance in the image is combined to perform auto iris control.
[0023]
Areas (1) to (4) in FIGS. 3 to 5 are areas obtained by dividing the photometric area in the image. FIG. 3 is a diagram showing an example of weighting of photometry in each divided area on the screen at the time of normal photographing. The area (1) is 10%, the area (2) is 40%, and the area (3) is 30%. , Region (4) is weighted by 20%. Here, when the image pickup unit 101 is rotated upside down, the upside down detector 81 is turned on, and the microcomputer 73 is notified that the image pickup unit 101 is upside down. At this time, the microcomputer 73 recognizes that the photometry data input from the photometry / ranging circuit 71 is upside down, and as shown in FIG. 4, the weighted average value obtained by performing weighting upside down from FIG. And auto-iris control by combining the maximum brightness in the screen. The weighting of each photometric area in FIG. 4 is, for example, 30% in the area (1) as in the area (3) in FIG. 3, 40% in the area (2) as in the area (2) in FIG. 3, and (3). Is 10%, the same as the area (1) in FIG. 3, and the area (4) is 20%, the same as the area (4) in FIG. Thus, an important subject such as a person can be photographed under appropriate exposure conditions.
[0024]
When the photometric data is detected from the image after the upside down, the image is held for a certain period during the inversion in the memory, and the photometric data is delayed information. In exposure control in which it is necessary to optimize exposure at high speed, this delay time causes performance deterioration, and therefore it is necessary to detect the delay before performing memory processing.
[0025]
Further, as a result of the microcomputer 73 performing autofocus control based on the distance measurement data input from the photometry / distance measurement circuit 71 in a state where the imaging unit 101 is rotated and turned upside down, the distance to the subject is within 10 cm to 1 m. If there is, face-to-face shooting is determined. Face-to-face shooting is shooting in a state in which a subject is a person and the subject is a photographer, and the distance between the imaging device and the subject is generally about 10 cm to 1 m. . When the microcomputer 73 determines that face-to-face shooting is performed, as shown in FIG. 5, a weighted average is obtained by weighting such that photometry is performed with emphasis on a person who is a subject, and auto iris control is performed. In this case, the maximum luminance on the screen is not reflected on the photometric data because it is affected by a person other than the person who is the subject. Therefore, as an example of weighting in each photometric area in FIG. 5, the area is 40%, the area (2) is 60%, the area (3) is 0%, and the area (4) is 0%. With the weighting as shown in FIG. 5, a person as a subject can be photographed with proper exposure during face-to-face photographing.
Although the embodiments have been described above, the present invention is not limited to these examples, and it goes without saying that various modifications are possible.
[0026]
According to the imaging device according to each embodiment of the present invention, even when the imaging unit is rotated upside down, an image recorded on a recording medium or the like can be recorded in a normal state. In addition, even when the imaging unit is turned upside down, by appropriately adjusting the weight of the weighted average of the auto iris control, an important subject such as a person can be photographed under appropriate exposure conditions. Furthermore, when it is determined from the autofocus control information that face-to-face shooting is to be performed, a person as a subject can be shot under appropriate exposure conditions.
[0027]
【The invention's effect】
The imaging device according to the present invention can record an image in a normal position on a recording medium even when the imaging unit is rotated upside down. Further, even if the image pickup unit is turned upside down, the weight of the weighted average of the auto iris control can be appropriately changed, so that an important subject can be photographed with proper exposure. Furthermore, when it is determined from the autofocus control information that face-to-face shooting has been performed, the subject can be shot with proper exposure.
[Brief description of the drawings]
FIG. 1 is a functional block diagram illustrating a configuration example of an imaging device according to a first embodiment of the present invention.
FIG. 2 is a functional block diagram illustrating a configuration example of an imaging device according to a second embodiment of the present invention.
FIG. 3 is a diagram illustrating the distribution of auto iris control weights for each area during normal shooting.
FIG. 4 is a diagram illustrating a distribution of weights for auto iris control when the imaging unit is inverted.
FIG. 5 is a diagram illustrating weighting for auto iris control during face-to-face shooting when the imaging unit is inverted.
6A and 6B are schematic diagrams illustrating an example of an external configuration of a camera unit rotary imaging device. FIG. 6A is a perspective view when viewed obliquely from the front, and FIG. It is a perspective view at the time of seeing.
FIG. 7 is a schematic diagram illustrating an example of an external configuration of the camera unit rotary imaging device, and is a perspective view when viewed from obliquely front in a face-to-face shooting mode, and is a diagram illustrating a configuration after a liquid crystal monitor is rotated. is there.
[Explanation of symbols]
3, 53: lens, 5, 55: CCD image sensor, 7, 57: CDS / AGC, 11, 61: A / D converter, 15, 65: camera signal processing unit, 17: memory (for even field), 21 ... Memory (for odd-numbered fields), 23 .vertical inverted memory read circuit, 25 .vertical inverted circuit, 27 .recording circuit, 31, 83 iris, 71 photometric / ranging circuit, 73 microcomputer, 75 iris drive circuit , 77: lens driving circuit, 33, 81: upside down detector.

Claims (8)

An imaging apparatus having a recording unit and an imaging unit provided to be relatively rotatable with respect to the recording unit,
A signal processing unit that processes a first electric signal output from the imaging unit;
A vertical inversion detector that detects vertical inversion of the imaging unit,
An image pickup apparatus comprising: a vertical inversion circuit that performs processing to display image data generated by an output signal from the signal processing unit in a vertically inverted manner based on a result of the vertical inversion detector detecting the vertical inversion. The imaging device according to claim 1, further comprising a recording circuit that records a second electric signal output from the upside down circuit. The upside down circuit,
An image memory for storing the first electric signal;
The imaging apparatus according to claim 1, further comprising: an electric signal reading unit that counts down and reads an address of the electric signal stored in the image memory. The upside down circuit,
A first memory for storing the first electric signal of an even field;
A second memory for storing the first electric signal of an odd field;
An electric signal readout unit that alternately inverts and reads out an electric signal stored in the first memory and an electric signal stored in the second memory for each field. 3. The imaging device according to 1 or 2. A recording section; an imaging lens, an imaging element, and an iris provided between the imaging lens and the imaging element and driven by an iris driving circuit, the imaging section being provided so as to be relatively rotatable with respect to the recording section. An imaging unit comprising:
A vertical inversion detector that detects vertical inversion of the imaging unit,
A signal processing unit that processes a first electric signal output from the imaging unit;
An up / down inversion circuit that performs processing for up / down display of image data generated based on the first electric signal based on a detection result of the up / down inversion detector;
A divided photometric detection circuit that divides the image data into a plurality of photometric areas and performs photometry;
Based on the detection result of the upside-down inversion by the upside-down inversion detector, calculates a weighting degree of photometry for each of the divided photometry areas in the image data inverted upside-down, and controls the iris driving circuit based on the weighting degree. An imaging device having a control unit that performs the operation. An auto iris control unit that automatically adjusts an aperture of the imaging lens by driving an iris driving circuit based on a luminance level of image data based on the first electric signal;
The imaging apparatus according to claim 5, further comprising: an autofocus control unit that performs focusing control and automatically determines whether or not face-to-face shooting is performed based on a focusing distance. A recording unit, an imaging lens, an imaging device and an imaging unit having an iris provided therebetween, an exposure control method in an imaging device in which the imaging unit is relatively rotatably mounted via a rotation mechanism,
Dividing the image into a plurality of photometric areas;
A vertical inversion detecting step of detecting the vertical inversion of the imaging unit;
A subject discriminating step of determining whether or not the subject is a subject in face-to-face shooting by autofocus control when the upside-down inversion is detected in the upside-down inversion detection step;
A weighting step of weighting photometry for each of the divided photometry areas based on the determination result of the subject determination step;
Performing photometry for each of the photometric areas divided based on the weighting,
Automatically controlling the iris based on the result of the photometric step. A weighting step of weighting each of the divided photometric areas based on a determination result by the subject determination step,
8. The exposure control method according to claim 7, further comprising the step of, when it is determined that the face-to-face shooting is performed, increasing a weight of photometry for the subject in the divided photometry area and performing photometry.

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