JPH08223488A - Television camera device - Google Patents

Abstract

PURPOSE: To attain gradation reproduction of a high luminance part over a saturation level of a solid-state image pickup element by utilizing an electronic shutter function of a CCD. CONSTITUTION: A picture element signal by one field is generated from a different light reception storage time from odd-numbered horizontal picture element lines and even-numbered horizontal picture element lines of picture elements arranged on a base of a solid-state image pickup section 1000 and the two picture element signals are converted into a video signal by picture element/ video circuits 3100,3200. The video signal generated in a longer light receiving storage time in the two video signals is subject to high luminance compression in a ν correction compression circuit 4000 and added to the video signal generated in a short light receiving storage time at an adder 5000 to generate a video signal for one field. Thus, highlight part and low luminance part are simultaneously reproduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television camera device using a solid-state image pickup device such as a CCD.

[0002]

2. Description of the Related Art Conventionally, in a television camera device using a solid-state image pickup device such as a CCD, an image is produced by performing a plenary process and a knee process according to the maximum signal output level (saturation level) of the solid-state image pickup device. By compressing the high-luminance component of the signal, it contributes to the reproduction of an image with a large luminance difference (dynamic range).

FIG. 7 shows an example of high-brightness compression by a pudding process and a knee process of a conventional television camera device.
First, the prinny processing circuit normally compresses high-luminance components of about 200% (point D in FIG. 7) or more. For example, a high luminance component of about 600% (point A in FIG. 7) is 300%.
(The point B in FIG. 7) is compressed.

After the pleni processing, a gamma circuit, a contour compensating circuit and the like are used, and then the knee processing circuit compresses luminance components of about 95% (point E in FIG. 7) or more. For example, the high-brightness component of about 300% (point B in FIG. 7) after the pliny process is compressed to about 105% (point C in FIG. 7).

However, in the conventional television camera device as described above, for a subject having a high brightness portion equal to or higher than the maximum signal output level (saturation level, usually about 600%) of the solid-state image pickup device such as CCD, Due to the saturation of the output level and the compression such as the Prinny process and the Knee process, the high-luminance component is limited to a substantially constant level.

Conventionally, this problem has been dealt with by adjusting the aperture (iris) and shutter speed of the camera to lower the overall signal level. However, with such a method, when capturing a scene with a large luminance difference, such as when capturing an image of a person indoors outdoors (outside the window), the level of the low-luminance portion also drops,
Since it becomes difficult to see, there is a problem that the high-luminance portion and the low-luminance portion cannot be reproduced at the same time.

[0007]

As described above, in the conventional television camera device, the reproduction of the high-luminance portion is limited by the maximum signal output level (saturation level) of the solid-state image sensor such as CCD. There are problems that the reproduction of the gradation of the high-luminance portion exceeding the saturation level becomes almost constant, and that the reproduction of the high-luminance portion and the low-luminance portion cannot be performed at the same time.

The present invention has been made to solve the above-mentioned problems, and it is possible to reproduce a high-brightness portion above the saturation level of a solid-state image sensor, and to reproduce a high-brightness portion and a low-brightness portion at the same time. A wide dynamic range television camera device is provided.

[0009]

In order to achieve the above-mentioned object, a television camera device according to the present invention controls pixel signals for one field by driving pulses, and outputs pixel signals for one field to odd-numbered horizontal pixel lines and even-numbered horizontal pixel lines. The second horizontal pixel line and the second horizontal pixel line are generated at different light receiving and accumulating times, and the pixel signal of the light receiving and accumulating time of one of these two pixel signals is equal to or shorter than the light receiving and accumulating time of the one pixel signal is set as the first pixel signal, and the other is left. Solid-state image pickup unit that outputs two systems using the pixel signal of No. 2 as a second pixel signal, a drive pulse generation unit that generates a drive pulse for controlling the solid-state image pickup unit, and a first pixel signal and a second pixel signal, respectively. , A pixel / video converting means for converting into a second video signal, a level correcting means for correcting the first and second video signals to appropriate levels, respectively, and a first and a first level corrected by the level correcting means. By adding the video signal so as to configured by including an adding means for generating a video signal of one field.

[0010]

In the television camera device having the above structure,
Pixel signals for one field are generated at different light-receiving and accumulating times for the odd-numbered horizontal pixel lines and the even-numbered horizontal pixel lines of the pixels arranged on the substrate of the solid-state imaging unit, and these two pixel signals are generated. After being converted into video signals by the pixel / video conversion means, respectively, a video signal having a shorter light-receiving and accumulating time (either one in the case of the same) and a video signal having a longer light-receiving and accumulating time (the one remaining in the same case) Are corrected to appropriate levels and added to generate a video signal for one field.

That is, the high-intensity part of the object imaged by the solid-state image pickup part, which is equal to or higher than the saturation level in the normal light-reception accumulation time, is captured as a pixel signal which does not reach the saturation level by being imaged in a short light-reception accumulation time. The low-luminance portion is captured as a normal pixel signal by being imaged for a light-reception and accumulation time that is longer than the above-described short light-reception and accumulation time, and is corrected to an appropriate level by the level correction means in the subsequent stage, so that the low-luminance portion changes from high-luminance to low-lightness. It is possible to reproduce even brightness at the same time.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows the configuration of a television camera device according to the present invention. Solid-state imaging unit 1000
Is a solid-state image pickup device using a CCD, and photoelectrically converts incident light according to a CCD drive pulse from the CCD drive circuit 2000 and accumulates the pixel signal for one field into an odd line signal and an even line signal. And pixel signal O
Output as SA and OSB. These pixel signals O
SA and OSB are pixel / video conversion circuits 3100 and 3200, respectively.
Is supplied to.

Pixel / video conversion circuits 3100 and 3200 are each composed of a noise reduction circuit such as a correlated double sampling circuit or a delay difference noise removal circuit and convert a pixel signal into a video signal. The video signal output from the pixel / video conversion circuit 3200 is directly supplied to the adder 5000, and the video signal output from the pixel / video conversion circuit 3200 is supplied to the knee correction compression circuit 4000.

The knee correction compression circuit 4000 performs knee correction for compressing the high luminance component of the input video signal.
Here, the video signal subjected to high-intensity compression is the above-mentioned adder 5000.
Are added to the video signal from the pixel / video conversion circuit 3100 and output as a video signal for one field.

Next, referring to FIG. 2, the solid-state image pickup unit 1000 described above.
The specific configuration of will be described. FIG. 2 is a diagram showing the configuration of the solid-state imaging unit 1000. In this solid-state imaging unit 1000, photodiodes 1111 to 11mn for performing photoelectric conversion and accumulating charges are arranged on a semiconductor substrate in a grid pattern in m rows (horizontal rows) and n columns (vertical columns), and vertical CCDs 1201 to 120n. Are provided adjacent to the vertical pixel lines V1 to Vn which are the columns of the photodiodes.

The vertical CCDs 1201 to 120n have CCD drive pulses FVI1 to CCD supplied from the CCD drive circuit 2000 described above.
The charge stored in each field of the corresponding vertical pixel lines V1 to Vn, which is controlled by the FVI4, is read out. The charge groups of odd-numbered pixels on the vertical pixel lines V1 to Vn (hereinafter referred to as odd charge groups) are read out. And a charge group of an even-numbered pixel (hereinafter abbreviated as an even charge group) and read out at once.
The read charges are freely transferred in the vertical direction without being added. The read odd charge group and eve
One of the n charge groups is transferred to the memory units 1311 to 131n,
The other is transferred to the inverting memory units 1321 to 132n.

Memory units 1311 to 131n and inversion type memory unit
1321 to 132n are arranged adjacent to the upper and lower ends of the corresponding vertical CCDs 1201 to 120n on the semiconductor substrate, respectively, and are supplied from the CCD driving circuit 2000.
Drive pulses FVS1 to FVS4 and FVC1 to FVC
Controlled by 4 respectively.

The memory units 1311 to 131n transfer the transferred charge groups to the horizontal CCD 1410 one pixel at a time in the order of transfer. The inverting memory units 1321 to 132n are
A signal transfer unit (not shown) is formed in a circle, and by transferring in the memory, the transferred charge groups are transferred to the horizontal CCD 1420 in units of one pixel in the reverse order of the transfer order. Forward.

That is, of the odd charge group and the even charge group, one of them is a memory unit 1311 to 131n, and the other is an inversion type memory unit 1321 to 132n.
The charges for one row of the horizontal pixel lines H1 to Hm are transferred to 10 and the horizontal CCD 1420 without being added.

The horizontal CCD 1410 and the horizontal CCD 1420 are
The memory units 1311 to 131n and the reversal type memory units 1321 to 132n are arranged on one end of the semiconductor substrate, which is not adjacent to the vertical CCDs 1201 to 120n, respectively. The transferred charges for one row of the horizontal pixel lines H1 to Hm are output to the output amplifiers 1510 and 1520 without being added, respectively.

The output amplifiers 1510 and 1520 amplify the pixel signals and output them as pixel signals OSA and OSB, respectively. Next, the drive pulse supplied by the CCD drive circuit 2000 will be described with reference to FIGS. FIG. 3 is a diagram showing an example of drive pulses supplied by the CCD drive circuit 2000. The left half surface and the right half surface of FIG.
9 illustrates an example of drive pulse output in a dd field and an even field.

First, the case of the odd field will be described. In the blanking period A, the electric charges remaining in the vertical CCDs 1201 to 120n are swept by the high-speed sweep pulse. In the following period FS1, only the odd charge group on the pixel is transferred to the vertical CCD 12
The data is read (field shift) from 01 to 120n and transferred to the inversion type memory units 1321 to 132n during the period B. Then, the period FS
In step 2, only the even charge group is read out to the vertical CCDs 1201 to 120n (field shift).

However, it is assumed that the charge group read out in the period FS1 is set by the electronic shutter function of the CCD to be equal to or shorter than the light receiving and accumulating time (shutter speed) of the charge group read out in the period FS2.

During the next C period, the vertical CCDs 1201 to 120n
The even charge group read out to the memory unit 1311 to 131n is transferred. During the period C (the period C ′ in FIG. 2), the transfer operation is continued on the inversion storage side, and the process of inverting the order of the transferred charges is performed.

Next, the case of the even field will be described. In the blanking period A, after the charges remaining in the vertical CCDs 1201 to 120n are similarly swept out by the high-speed sweeping pulse, in contrast to the above-mentioned odd field, the e
vertical CCDs 1201 to 120n in the period FS1 only for the ven charge group
, And transfer to the inverting memory units 1321 to 132n during the period B. Next, in the period FS2, only the odd charge group is read out to the vertical CCDs 1201 to 120n.

That is, by controlling the driving pulse as described above, the transfer targets (memory sections 1311 to 131n, inversion type memory sections 1321 to 132n) of the odd charge group and the even charge group and the light reception accumulation time are switched field by field. Of the electric charge group and the even electric charge group, the electric charge group having the shorter light-receiving and accumulating time (either one in the case of the same) is the inverting memory unit 1321 to
132n, horizontal CCD 1420 and output amplifier 1520
The electric charge group that is output as the pixel signal OSA via the horizontal direction and has the longer light-receiving and accumulating time (the other remains when the same is the case) is supplied to the memory units 1311 to 131n, and passes through the horizontal CCD 1410 and the output amplifier 1510 to generate the pixel signal OSB. Is output as.

The operation of the television camera device having the above configuration will be described below with reference to FIG. FIG. 4 is a diagram showing a characteristic of a video signal output with respect to incident light. The high-brightness portion of the subject that is at or above the saturation level captured by the solid-state image capturing unit 1000 is captured as a pixel signal OSA that does not reach the saturation level by capturing an image in a short light reception and accumulation time using the electronic shutter function of the CCD. On the other hand, the low-brightness portion is captured as a normal pixel signal OSB by being imaged for a light reception / accumulation time longer than the short light reception / accumulation time. The pixel signal OSA and the pixel signal OSB thus imaged are converted into a first video signal (broken line A in FIG. 4) and a second video signal, respectively.

The second video signal is a knee correction compression circuit 4000.
Is corrected to an appropriate level by high-intensity compression (dotted line B in FIG. 4), added with the first video signal by the adder 5000, and is inclined (gradation) as shown by the solid line (A + B) in FIG.
Is output as a 1-field video signal.

At this time, the knee correction compression for the second video signal is less than or equal to the clip level of the white clip circuit provided in the subsequent stage (usually 95% to 105% to 110%).
By setting it to (1), the video signal output from the adder 5000 is prevented from being compressed with high brightness by the white clip circuit, and the high brightness part reproduction effect is enhanced.

In the prior art, there is also a method of improving the vertical resolution by applying an electronic shutter to one pixel signal of the two-system output pixel signals, but in this case, no shutter is applied (light reception accumulation time). Since the output of the solid-state image pickup unit remains unchanged, the high-brightness part of the video signal obtained by addition is compressed by the subsequent knee and gamma circuits, and the effect of improving the dynamic range is hardly obtained.

According to the electronic shutter function of separately applying the electronic shutter as in the present invention, for example, the pixel signal OSB is generated without the electronic shutter (the lowest shutter speed) at 1/60 seconds, for example. Compared to the case, when the pixel signal OSA is generated at a shutter speed of 1/600 seconds, a high-luminance portion 10 times as high as when the shutter is not applied can be taken out at the same time. That is, if the maximum output level is 600%, the solid-state imaging unit can take out a signal that is ten times as high, that is, 6000%, and at the same time, the low-luminance portion can be taken out by the pixel signal OSB.

Therefore, in the conventional television camera device, due to the characteristics of the image pickup device, the gradation of only a signal up to about 600% could be reproduced.
It is possible to reproduce up to several thousand% of the signal according to the shutter speed characteristic of the CD, and it is possible to simultaneously reproduce from high brightness to low brightness.

The present invention is not limited to the above embodiment. In the above embodiment, the two-wire simultaneous reading method C is used.
The case where a CD image sensor is used has been described.
The present invention can be applied to any other image pickup element as long as the element can perform the same reading.

Further, as shown in FIG. 5, a white clip circuit is provided in place of the knee correction compression circuit for a video signal having a long light receiving and accumulating time, and a video signal obtained by adding the white clip circuit ( The same effect can be obtained by removing the high-brightness portion to a level at which it is not clipped (not shown).

Furthermore, in the above, the odd charge group and even
Although the charge groups are separately read and transferred, the present invention is also applicable to a television camera device using a solid-state imaging unit that can simultaneously read and transfer charges from odd-numbered pixels and even-numbered pixels.

FIG. 6 is a diagram showing an example of a charge read pulse of a television camera device capable of simultaneously reading charges. The read pulse FSA and the read pulse FSB in FIG. 6 are read pulses for odd-numbered pixels and even-numbered pixels, respectively. Periods t1 and t
2 both represent the received light storage time. In this case, the pixels to be read are replaced for each field.

As described above, by performing the light receiving and accumulating time t1 and the light receiving and accumulating time t2 at the same time (overlapping period), it is possible to apply to a solid-state image pickup section in which charges are simultaneously transferred. In addition, performing the light reception accumulation time at the same time (overlapping periods) also contributes to resolution improvement. Other,
It goes without saying that various modifications can be made without departing from the gist of the present invention.

[0038]

According to the present invention, it is possible to reproduce the gradation of the high-luminance portion above the saturation level of the solid-state image pickup element, and to reproduce the high-luminance portion and the low-luminance portion at a wide dynamic range. A television camera device can be provided.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a television camera device according to the present invention.

FIG. 2 is a diagram illustrating a configuration example of a solid-state imaging unit according to the above-described embodiment.

FIG. 3 is a diagram showing an example of drive pulses for the solid-state imaging unit of the above-described embodiment.

FIG. 4 is a diagram illustrating characteristics of an image signal output with respect to incident light luminance in the above-described embodiment.

FIG. 5 is a diagram for explaining characteristics of a video signal output with respect to incident light luminance when a white clip circuit is used instead of the knee correction compression circuit of the above embodiment.

FIG. 6 is a diagram showing an example of a read pulse when a solid-state imaging unit that simultaneously transfers charges is used.

FIG. 7 is a diagram illustrating knee correction compression of a conventional television camera device.

[Explanation of symbols]

1000 ... Solid-state imaging unit, 1111-1mn ... Photodiode, 12
01-120n ... Vertical CCD, 1311-131n ... Memory part, 1321-
132n ... Inversion type memory unit, 1410, 1420 ... Horizontal CCD, 151
0,1520 ... Output amplifier, 2000 ... CCD drive circuit, 3100,3
200 ... Pixel / video conversion circuit, 4000 ... Knee correction compression circuit, 5
000 ... Adder, H1 to Hm ... Horizontal pixel line, V1 to Vn
… Vertical pixel lines.

Claims (5)

[Claims] 1. A pixel signal for one field, which is controlled by a drive pulse, is generated in an odd-numbered horizontal pixel line and an even-numbered horizontal pixel line at different light receiving and accumulation times. , A pixel signal whose light-reception accumulation time is equal to or shorter than the light-reception accumulation time of one pixel signal is used as a first pixel signal, and the other remaining pixel signal is used as a second pixel signal.
A solid-state image pickup unit that outputs a system, a drive pulse generation unit that generates a drive pulse that controls the solid-state image pickup unit, and a pixel that converts the first and second pixel signals into first and second video signals, respectively. / Video conversion means, level correction means for correcting the first and second video signals to appropriate levels, respectively, and the first and second levels corrected by the level correction means
And a video signal of 1 field to generate a video signal of one field. 2. The solid-state imaging unit exchanges the light-receiving and accumulating times of the odd-numbered and even-numbered horizontal pixel lines for each field to generate the first and second pixel signals. The television camera device according to claim 1. 3. The television camera device according to claim 1, wherein the level correction means corrects the level of a high-luminance portion of the second video signal. 4. The television camera device according to claim 3, wherein the level correction means performs high brightness compression by knee correction. 5. The television camera device according to claim 3, wherein the level correcting means removes a high-luminance portion by a white clip.