JPH06113195A - Video camera device - Google Patents

Abstract

PURPOSE:To obtain a natural picture which is bright in the whole picture by performing a partial luminance-correction of only the area of high luminance in the picture by controlling the quantity of light of the arbitrary area of the picture. CONSTITUTION:Object light 4 is converted into charge by an image pickup device 2, and is converted into video signal output 5 through a camera signal processing circuit 3. The data of this first field is sent to the high-luminance area detection circuit 9 of a luminance correction circuit 14, and a high- luminance part is detected from an infinitesimal area obtained by dividing a field in a vertical direction and a horizontal direction. Then, a read-out control circuit 11 performs feedback-control of it in accordance with a sent read-out control signal 10 so that only the divided area designated by the next field generates the charge. Namely, the charge is reset only in the high-luminance area, and the luminance is reduced. On the other hand, there is no reset on the charge of the area of the appropriate luminance. The obtained video signal output 5 is fetched to a memory 8 after being A/D-converted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video camera device, and more particularly to a video camera device having a function of partially controlling the screen brightness.

[0002]

2. Description of the Related Art In the brightness correction of a conventional video camera, when a high brightness portion is detected in a field, in order to uniformly reduce the charge of the image pickup tube target or the charge of each pixel of the solid-state image pickup element in the field, an automatic or A method is adopted in which the exposure is manually adjusted to prevent the electric charge of the image pickup device from being saturated.

As a case where a high-intensity part is detected in the field, a subject may be photographed under a backlit condition.
At that time, a method of performing backlight compensation using a backlight compensation switch or manually performing aperture compensation has been used.

[0004]

In the brightness correction in the field by the method shown in the above-mentioned conventional example, since the exposure correction is applied to the entire field including the high brightness portion, the brightness is appropriate. No consideration has been given to the part. Therefore, even if it is possible to prevent the saturation of the charges of the pixels of the image pickup device corresponding to the high brightness portion, the entire field becomes dark due to the decrease of the charges of the other pixels.

Therefore, an object of the present invention is to provide a video camera device in which only the high brightness area of the screen is partially brightness-corrected so that the entire screen becomes a bright and natural image.

[0006]

According to the present invention, it is possible to correct the brightness of each field area in a video camera device having a field shooting speed several times higher than usual (hereinafter referred to as a double speed camera). . First, the image information for one field is A / D converted, and then the image data is sent to the brightness correction circuit. Then, the field is divided into areas, high-luminance areas are detected, and a control signal is sent to the pixel readout circuit. Next, depending on the multiple of the double speed camera and the charge saturation time of the image pickup device, for some fields within that multiple, the readout area control of the image pickup device is performed so that only the image information of the divided area can be read. Put a field back on. In the frame memory, the image information of the high brightness area and the image information of the appropriate brightness area are combined and stored. In this way, the 1-field image data output from the frame memory cannot be processed at the shooting speed of the double-speed camera, but the charges in the high-brightness area are taken into the frame memory before they are saturated. The luminance area is saved as it is, and only the high luminance area can be luminance-corrected and output.

Further, according to the present invention, a controllable transmittance variable member is provided between the lens and the image plane, and the transmittance variable member is controlled to control the partial brightness (light amount) of the screen. To do.

According to the present invention, the electronic camera device is provided with an image memory for one screen or more, the screen is divided into a plurality of areas, and the brightness level is detected for each area.
The image of the area within the proper brightness level range is recorded in the image memory, the exposure condition is changed again, the image is taken, and the image of the area within the appropriate brightness level range is additionally recorded in the image memory, and the final image is recorded. As a practical matter, a video signal whose entire screen is within the proper luminance level range can be output.

[0009]

EXAMPLE An example in which the present invention is applied to a double speed video camera will be described. FIG. 1 shows a double speed video camera system used for implementing the present invention. An imaging device 2 and a camera signal processing circuit 3 are included in the triple speed video camera 1. Here, the image pickup device refers to, for example, an image pickup tube or a solid-state image pickup device of an XY address system. Although only one image pickup device is shown in FIG. 1, this may be a single-tube type or a three-tube type. Only one imaging device is shown here to avoid complication of the drawing.

The object light 4 is converted into electric charges by the image pickup device 2, and the image information of the first field is converted into a video signal output 5 through the camera signal processing circuit 3. The video signal 5 is converted into digital data by the A / D conversion circuit 7 in the frame memory 6. The digital data of the first field is sent to the high brightness area detection circuit 9 of the brightness correction circuit 14 and the high brightness portion is detected.

FIG. 2 shows a state in which image data for one field is vertically and horizontally divided into areas. Of these minute areas, areas containing high-luminance components are designated and detected at vertical and horizontal positions on the screen. Here, first, image data for one field is divided into minute areas by uniformly or arbitrarily dividing the field in the vertical and horizontal directions. Then, after determining the field division area including the high brightness portion, the read control signal 10 is sent to the read control circuit 11. The read-out control circuit 11 field-back controls the read-out control signal of the image pickup device according to the read-out control signal 10 sent, and in the second field and the third field, the read-out is turned on only in the designated divided areas. To be Then, the charge is reset in the pixel whose reading is on and new charge is generated.

FIG. 3 shows a state of charge accumulation amount of pixels of an image pickup device corresponding to a high brightness area and an appropriate brightness area when the present invention is applied to a triple speed camera. In the designated divided area, electric charges are newly generated in the next field and thereafter, so that the electric charges are reset only in the high luminance area and the luminance is reduced. On the other hand, since the charges are not reset in the proper luminance area, the charges of the pixels of the image pickup device increase with time. In this way, by applying the field back to the reading on / off of the image pickup device, the image information of the second field and the third field is updated only in the high-brightness area, so that the charge saturation of the pixels in the high-brightness area is saturated. Can be prevented.

The video signal output 5 thus obtained is A /
After the D conversion, the digital data is taken into the memory 8 in the frame memory so that the digital data in the high brightness area is brightness-corrected but the data in the proper brightness area is not corrected. Become. That is, in the image data for the three fields from the first field to the third field, only the output due to the charges generated in the third field is adopted in the high brightness area, and the appropriate brightness area is the third field in the third field.
The output due to the electric charges generated in the pixels of the image pickup device during the period up to the field is adopted and taken into the frame memory 6, so that the image data for one field is combined. The 1-field data thus obtained is converted into an analog video signal output 13 by the D / A conversion circuit 12 and output. The output of the triple speed video camera becomes standard speed output, and the original function of the triple speed video camera is not fulfilled, but it is possible to correct only the high brightness area of the field having the high brightness part, and the proper brightness area has no problem. Since there is no influence, it is possible to obtain a natural image in which the entire screen is bright.

FIG. 4 is a diagram for explaining another embodiment, and shows a state in which an appropriate brightness area surrounding a high brightness area is smoothly corrected by two-step correction of the next field and the next field. is there.

Further, FIG. 5 shows a state of the charge accumulation amount of the pixels of the image pickup device corresponding to the high brightness area and the correct brightness area to be corrected when the two-step correction shown in FIG. 4 is performed.

In this embodiment, when the field division area is designated, the high-brightness area detection circuit detects the high-brightness area, and then the area including the high-brightness area is first read. Next, only the high-brightness area is read in the next frame or the next frame, and the brightness correction area is set stepwise. In this way, the boundary between the high-luminance area and the proper-luminance area becomes inconspicuous, and the naturalness increases.

It should be noted that the multiple of the double speed video camera is 4 times or 6 times.
If it is twice as large, even if the high-brightness area correction of the present invention is performed and the number of fields is reduced, the standard number of fields is 2
Since it is only necessary to set the number of correction fields so that the field can be output at double and triple field shooting speed, the original utility of the double speed video camera can be maintained.

When the present invention is applied to a double-speed video camera device, by controlling the reading means of the image pickup device, it is possible to partially correct the brightness of only the high-brightness area of the screen, and the whole screen is bright and natural. It is possible to obtain a clear image.

Although the above-described embodiment has been applied to a double speed camera, a case where it is applied to a normal camera will be described.

FIG. 6 is a block diagram of a video camera according to an embodiment of the present invention. 21 is a lens system including a diaphragm, 22 is a filter whose transmittance can be partially controlled,
Reference numeral 23 is an image sensor, 24 is a camera signal processing circuit, 25 is a brightness difference detection circuit for detecting a difference in brightness level within the screen and an average brightness level, 26 is an aperture control circuit for driving an aperture inside the lens system, and 27 is It is a control circuit for controlling the filter 22.

Further, FIG. 7 shows an example of the filter 22 whose transmittance can be partially controlled as shown in FIG. 6, and it is assumed that the hatched portion in the drawing is controlled so that the light amount becomes 1/2.

The light emitted from the subject is imaged on the image pickup device 23 by the lens system 21, converted into an electric signal by the image pickup device 23, processed by the camera signal processing circuit 24, and then output from the output terminal as a camera output. It Up to this point, it is the same as the conventional one.

The luminance signal extracted by the camera signal processing circuit 24 is input to the luminance difference detection circuit 25. The brightness difference detection circuit 25 uses a diaphragm control circuit 26 based on the average brightness of the entire screen.
And the control signal of the partial filter control circuit 27 based on the brightness difference in the screen.

As a means for detecting the brightness difference, as shown in FIG. 8, the screen is divided into a plurality of areas (16 areas of 4 × 4 in FIG. 8), and the average brightness level of each area is compared to detect the difference. it can. FIG. 9 shows a specific configuration example of the brightness difference detection circuit 25. In the figure, reference numeral 41 denotes an integrating circuit, which integrates the luminance signal of only a part of the region divided by FIG. 8 based on the gate signal. The integrated signal is converted by the A / D conversion circuit 42 and input to the CPU 43. The CPU 43 extracts the average brightness of the screen, the maximum brightness, the minimum brightness, and the brightness difference in the screen from the digital value of the brightness level of each area, and outputs the aperture control signal and the partial filter control signal based on these results.

The filter 22 shown in FIG. 1 can be composed of, for example, a liquid crystal. When a video camera such as this is used to shoot a subject as shown in FIG. 10 (a) (when the sun appears in the upper right), a normal video camera is used as shown in FIG. 10 (b). The image becomes dark, but when the video camera of the present invention is used, the image shown in FIG.
The brightness level is detected for each area as shown in (c),
As a result, it is necessary to reduce the amount of light in the high brightness area on the upper
U43 generates the partial filter control signal, and as an example of the result, the transmittance of the area hatched in FIG. 7 is controlled.

FIG. 11 shows another embodiment of the present invention.

In the figure, 21 to 24 and 26 and 27 are the same as those in the above-mentioned embodiment. Reference numeral 61 denotes an area designating circuit capable of manually limiting the light amount in the upper right area when, for example, a subject as shown in FIG. 10C is photographed, and the simplest configuration example of this circuit is a region. It is to prepare the number of switches according to.

Further, since an important subject is often placed in the center of the screen in many cases, it is possible to limit the amount of light around the screen by the switch circuit 71 as shown in FIG. An example of the partial control filter in this case is shown in FIG.

In the above embodiment, the screen division is described as 4 × 4 16 areas, but the screen division method is 4 × 4.
It is not necessary to set the number to 4, and it is also possible to limit the light amount in pixel units by increasing the number of divisions, for example.

FIG. 14 shows an example of a filter capable of partially limiting the amount of light used in the present invention.

In FIG. 14, (a) is a diagram showing the whole of the filter capable of partially limiting the light amount, and shows a state where the light amount is limited in the hatched portion in the figure. Also, (b) is an enlarged view of the hatched portion of (a), where the black portion is the portion that does not pass light and the white portion is the portion that passes light. In this example, the transmittance is limited to about 50%. is doing.

Although the above example has been described assuming that the screen is divided into 16 of 4 × 4, the number of divisions is not limited in the present invention.

Further, in the above example, the light quantity is limited by the ratio of the area through which light passes and the area through which light does not pass. However, since the light quantity is the product of the light intensity and the irradiation time, the irradiation time is limited by limiting the irradiation time. Restrictions are possible. An example of the partial filter drive circuit 27 in this case is shown in FIG. Further, a method of controlling the transmittance by utilizing a transition region of liquid crystal as shown in FIG. 16 is also conceivable. An example of a drive circuit in this case is shown in FIG.

That is, the control signal is D / A converted into an analog signal, which is used as a filter control signal to control the driving of the liquid crystal.

A material having an electro-optical effect such as liquid crystal or PLZT is used as a member of the filter used in this embodiment.

FIG. 18 shows another embodiment of the present invention. In the figure, 21 is a lens, 22 is an image sensor, 23 is a camera signal processing circuit, 34 is a brightness level detection circuit, 26 is a lens aperture control circuit, 36 is an A / D conversion circuit, 37 is a memory circuit, and 38 is D. A / A conversion circuit.

The operation of this embodiment will be described with reference to FIG. First, it is assumed that the subject shown in FIG.
The circle in the upper right part of (a) is a high brightness subject such as the sun. The light emitted from the subject shown in FIG. 19A is imaged by the lens 21 in FIG. 18, converted into an electric signal by the image sensor 23, processed by the camera signal processing circuit 24, and processed by the A / D conversion circuit 36. Memory circuit 37, D /
It is output from the camera output terminal through the A conversion circuit 38. On the other hand, the camera signal processing circuit 24 outputs only the luminance signal to the luminance level detection circuit 34.

The brightness level detecting circuit 24 is shown in FIG.
Divide the screen into multiple areas as shown in (b),
(In the example of (b), 16 divisions of 4 × 4) An average luminance level for each area is detected. If the difference in luminance level between the areas is small (in the case of forward light), a normal electronic camera device is used. (For example, the highest brightness level in the screen is 1
A control signal for performing aperture control (so as not to exceed 00%) is output to the aperture control circuit 26. On the other hand, FIG.
When a subject having a large brightness difference as shown in (b) is photographed, an image photographed by normal aperture control (c)
Therefore, the area within the appropriate brightness range is set to the brightness level detection circuit 3
4 makes a decision, the A / D conversion circuit 36 converts it into a digital signal, and records it in the memory circuit 37. Next, the aperture control signal is corrected so that the area (the human part in the center of FIG. 7C) that was outside the proper luminance range in the previous photographing is within the proper luminance range. Switch between signal and output. The state is shown in FIG. (D) The peripheral portion of the figure is the video signal portion captured in the memory,
The central portion of the diagram (d) is the portion obtained by the second photographing. Further, FIG. 20 shows a block diagram of the luminance level detection circuit, and FIG. 21 shows a block diagram of the memory circuit.

The brightness level detecting circuit is composed of an integrating circuit 45 for integrating the brightness signal by a gate signal, and an A / D output of the integrating circuit 45.
It is composed of an A / D conversion circuit 46 for conversion and a CPU 47 for calculating and outputting an aperture control signal and an appropriate brightness area signal based on the output of the A / D conversion circuit 46.

The brightness level detection circuit also includes a memory 55 for storing digital video signals and a timing circuit 57.
And a memory control circuit 56 for controlling the storage operation of the memory 55 in response to the timing signal from the timing circuit 57 and the appropriate luminance area signal.

Although the above embodiment is an example in which the screen is divided into 16, the number of screen divisions is not limited to the present invention. Further, although the above-described embodiment is an example in which the results of two photographings are combined, the number of photographings does not impose any limitation on the present invention.

Although the exposure control is performed by controlling the diaphragm of the lens in the above embodiment, the present invention can be realized by using the electronic shutter function used in the solid-state image pickup device such as CCD. An example of this case is shown in FIG. Reference numeral 39 newly provided in FIG. 22 is a CCD electronic shutter circuit. In this case, the brightness level detection circuit 34 is shown in FIG.
The control signal is output to the aperture control circuit 26 and the electronic shutter circuit 39 is controlled so that the low-brightness area (the central portion in the figure (b)) in FIG. A control signal is output so that the outer part of the shutter becomes a shutter speed that is an exposure condition within the proper exposure range, the image is photographed, and then the center part of FIG. Output the signal for shooting. The composition of these two photographing results is the same as in the case of the previous embodiment. Further, by increasing the number of screen divisions and the number of times of photographing, it is possible to configure a screen that suppresses the brightness level difference and does not give an unnatural appearance.

The present invention can also be applied to a moving picture (video camera). When used in a moving picture, an image in an exposure state that is normally appropriate, that is, a state in which a high-luminance portion is properly exposed is loaded into a memory (at the same time), and thereafter, Move the exposure little by little in the direction of overexposure (the direction to open the iris). Of the image data obtained at this time, the image data in the memory is output for the overexposed areas, and the current image data is output for the areas that are not overexposed (at the same time it is loaded into the memory). This operation is repeated, and finally, the exposure correction is fixed in a state where the exposure state of the low-brightness area is within the lower limit of the proper exposure range. In this case, the image data in the high-brightness area is the old data in the memory, but there are not many important subjects in the high-brightness part of the image that requires backlight compensation, so use the old image data in the memory. Does not cause any inconvenience. However, if the video camera is panned or tilted in accordance with the movement of the subject at the center, it is rather unnatural to output image data that is too old. Therefore, it is more preferable to update the image data in the high-luminance area once every several fields or several frames. At this time (at the time of executing the update), the image data of the low brightness area may be output from the image memory. Further, since it is difficult to realize such a rapid change in exposure with the diaphragm of the lens, it is preferable to use the electronic shutter function of the video camera. That is, the exposure time of the electronic shutter may be determined based on the result of comparing the aperture value when the high-luminance area was previously captured with the current aperture value, or from the exposure time of the previous electronic shutter. further,
A more natural image can be obtained by calculating the exposure correction amount for the next high-luminance area shooting based on the exposure value of the high-luminance area this time.

[0044]

As described above in detail with reference to the embodiments, the present invention controls the amount of light in an arbitrary area of the screen. Correction is possible, and there is an advantage that backlight correction can be performed without giving an unnatural feeling to the entire screen.

[Brief description of drawings]

FIG. 1 is a diagram showing a double speed video camera system used in implementing the present invention.

FIG. 2 is a diagram showing a state in which image data for one field is vertically and horizontally divided into areas.

FIG. 3 is a diagram showing a state of charge accumulation amount of a camera tube target corresponding to a high brightness area and an appropriate brightness area when the present invention is applied to a 3 × speed camera.

FIG. 4 is a diagram for explaining another embodiment of the present invention.

5 is a diagram showing a state of charge accumulation amount of an image pickup tube target when the two-step correction shown in FIG. 4 is performed.

FIG. 6 is a diagram showing a block diagram of a video camera according to an embodiment of the present invention.

FIG. 7 is a diagram showing an example of a partial filter used in the present invention.

FIG. 8 is a diagram showing an example of screen division for detecting a brightness difference.

FIG. 9 is a block diagram showing a specific configuration of a brightness difference detection circuit.

FIG. 10 is a diagram for explaining the operation of the embodiment of the present invention.

FIG. 11 is a block diagram of a video camera showing another embodiment of the present invention.

FIG. 12 is a block diagram of a video camera showing still another embodiment of the present invention.

FIG. 13 is a diagram showing an example of a partial filter used in the present invention.

FIG. 14 is an enlarged view of the whole and part of the light amount variable member used in the present invention.

FIG. 15 is a circuit diagram and a filter drive waveform diagram of an embodiment in which the amount of light is limited by time.

FIG. 16 is a voltage-transmittance characteristic diagram of liquid crystal.

FIG. 17 is a diagram showing an example of a driver circuit when liquid crystal is used.

FIG. 18 is a block diagram of a video camera showing another embodiment of the present invention.

FIG. 19 is a diagram for explaining the operation of FIG. 18.

FIG. 20 is a block diagram showing an example of a brightness level detection circuit.

FIG. 21 is a block diagram illustrating an example of a memory circuit.

FIG. 22 is a block diagram of a video camera showing another embodiment of the present invention.

[Explanation of symbols]

 1 3x Video Camera Device 2 Image Pickup Tube 3 Camera Signal Processing Circuit 4 Object Light 5 Video Signal Output from Video Camera 6 Frame Memory 7 A / D Conversion Circuit 8 Field Memory (Multiple) 9 High Bright Area Detection Circuit 10 Beam Control Signal 11 beam deflection circuit 12 D / A conversion circuit 13 video signal output from frame memory 14 brightness correction circuit 21 lens 22 filter 23 image sensor 24 camera signal processing circuit 25 brightness difference detection circuit 26 aperture control circuit 27 partial filter control circuit 61 area Designation circuit 71 Switch circuit 36 A / D conversion circuit 37 Memory circuit 38 D / A conversion circuit 39 Electronic shutter circuit

Claims (7)

[Claims] 1. A memory means for storing image information on an imaging screen, a detecting means for detecting a brightness level of a predetermined area of the imaging screen, and an adjusting means for adjusting the brightness of an area including at least the predetermined area, A video camera device comprising: a driving unit that operates the adjusting unit to reduce the luminance of the predetermined area when the luminance level exceeds a predetermined value. 2. A correction means for correcting the screen brightness within the field by controlling the reading means a predetermined number of times during double-speed frame photography, wherein the memory means has a memory capacity for storing a plurality of field image information. The video camera device according to claim 1, further comprising a video camera device. 3. The video camera device according to claim 1, wherein the adjusting means is provided on the front surface of the image forming surface of the image sensor. 4. The video camera device according to claim 1, wherein the adjusting means is provided in a peripheral portion of the front surface of the image forming surface of the image pickup device. 5. The video camera device according to claim 3, wherein the adjusting means is made of a member capable of controlling the amount of transmitted light, and the transmission area of the member is variable. 6. The video camera device according to claim 3, wherein the adjusting means is made of a member capable of controlling the amount of transmitted light, and the transmittance of the member is variable. 7. A memory means capable of storing image information for one screen or more, a detection means for dividing a screen into a plurality of areas and detecting a brightness level for each divided area, and a plurality of exposure conditions being changed. Image information of an area determined to have a brightness level within the proper brightness range by the detection means is recorded in the memory means, combined with each other, and output. Characteristic video camera device.