JP3974290B2 - Imaging system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an imaging system.
[0002]
[Prior art]
Conventionally, in a TV (television) camera device as an imaging system, a signal input to a process circuit is reproduced by a clamp circuit, and then subjected to white clip, knee processing, and blanking for dynamic range compression. Insertion, gamma correction, black clipping, etc. are performed.
[0003]
In an ordinary TV camera device, an input signal exceeding the rated level (referred to as 100%) is compressed by the knee circuit to around 5 times the rated level (500%), and the signal exceeding the rated level is charged by a CCD (charge coupled device). As it approaches the saturation point, it is clipped. A value such as 500% is called a dynamic range. From 0% to 100% is obtained with a normal image quality, and from 100% to 500% is a low-contrast image quality due to compression. However, since it is reproduced as an image, it is allowed as a background image.
[0004]
[Problems to be solved by the invention]
For example, when shooting a person who is in the spotlight with such a TV camera device, when the iris is placed on the person, the resulting image will be dark around the person and the gradation of the dark part will be reproduced. Was not.
[0005]
Also, for example, when taking a picture of a person with such a TV camera device in backlight, when the iris is put on the person, the difference in brightness in the screen increases, and the bright part is clipped far exceeding 500%, so it is completely white. There was a case where nothing was reproduced. This is because the human eye can see the light and dark portions even in the backlight, but the TV camera device is saturated and cannot reproduce the bright portions.
[0006]
A first object of the present invention is to provide an imaging system that can solve the above-described problems and can further reduce the sinking of a dark part by a predetermined switch operation.
[0007]
The second object of the present invention is to provide an imaging system capable of solving the above-described problems and further reducing white stripes by a predetermined switch operation.
[0008]
A third object of the present invention is to provide an imaging system capable of solving the above problems and switching a plurality of knee points by a predetermined switch operation.
[0009]
[Means for Solving the Problems]
The imaging system of the present invention includes a normal mode setting switch for setting a normal mode, a backlight mode setting switch for setting a backlight mode, an amplification means for amplifying an RGB signal, and a gain of the amplification means. Gain control means for setting a default gain when the normal mode is set by the normal mode setting switch, and for setting a predetermined gain higher than the normal mode when the backlight mode is set by the backlight mode setting switch; to the signal from the amplification means, when said normal mode is set by the normal mode setting switch performs default knee processing, on the other hand, if the backlight mode is set by the backlight mode setting switch, two to-point From the knee point in normal mode. Knee processing means for lowering only the bell, and iris control means for controlling the iris in accordance with the knee point by the knee processing means.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0013]
<First Embodiment>
FIG. 1 shows a first embodiment of the present invention. This is an example of an NTSC (National Television System Committee) TV camera device. In FIG. 1, reference numeral 2 denotes a charge coupled device (CCD) which converts an optical signal incident through the lens 1 into an RGB signal. A preamplifier 3 amplifies the RGB signal from the CCD 2 with a predetermined gain. A gain amplifier 4 amplifies the RGB signal from the preamplifier 3, and the gain can be switched to either a default gain or three times. An auto knee processing unit 5 performs knee processing on the signal from the gain amplifier 4. Further, in the normal mode and the spot mode, the auto knee processing unit 5 sets a point that becomes 100 IRE with respect to the rated level (100%) as a knee point, and inputs 5 times the rated level (500%). 110 IRE is compressed to 100% to 500%, and an input signal exceeding 500% is clipped. Further, in the backlight mode, the auto knee processing unit 5 sets the point where the 80 IRE is 80 IRE as the knee point, and becomes 110 IRE when the input is 16 times (1600%) the rated level (100%). In this way, 80% to 1600% is compressed, and an input signal exceeding 1600% is clipped. An example of such image quality correction characteristics is shown in FIG. A process amplifier 6 performs gamma correction, contour correction, black stretch, and the like on the signal from the auto knee processing unit 5.
[0014]
7 is a control unit, and when the switch 8 is operated to switch to the normal mode, the gain of the gain amplifier 4 is set to the default gain, and the knee point of the auto knee processing unit 5 is changed to the knee point corresponding to the normal mode. When the switch 8 is operated to switch to the backlight mode, the gain of the gain amplifier 4 is tripled, the knee point of the auto knee processing unit 5 is switched to the knee point corresponding to the backlight mode, and the switch 8 is operated. When the mode is switched to the spot mode, the gain of the gain amplifier 4 is set to the default gain, the knee point of the auto knee processing unit 5 is switched to the knee point corresponding to the normal mode, and the process amplifier 6 applies the black stretch. Is what
[0015]
Reference numeral 9 denotes an auto iris control unit for interlocking auto iris settings in accordance with the knee processing of the auto knee processing unit 5.
[0016]
Since the present TV camera apparatus is configured as described above, when the switch 8 is operated and switched to the backlight mode, the gain of the gain amplifier is switched to 3 times by the control unit 7 and the dynamic range is increased to about 3 times. The point where the auto knee processing unit 5 becomes 80 IRE with respect to 80% is regarded as a knee point, and the input is 16 times (1600%) of the rated level (100%) so that it becomes 110 IRE. Then, 80% to 1600% is compressed, and an input signal exceeding 1600% is clipped. That is, the image quality correction characteristic is switched to the image quality correction characteristic in the backlight mode, and the reproduction range is greatly expanded. Further, the iris is narrowed down by the auto iris control unit 9, and the auto iris setting is linked so that the human image under backlight is 80 IRE or less.
[0017]
Therefore, although the S / N ratio is slightly reduced according to the gain (three times) of the gain amplifier, the obtained image is remarkably different from the conventional state where the bright part is completely white and nothing is reproduced. Are better. Therefore, reproducibility during backlighting is improved, and the imaging range of the TV camera device is expanded. However, an appropriate amount of the edge and color of the knee compression portion remains.
[0018]
Further, even in the case of direct light, it is effective when a bright part is included in the background. Therefore, this TV camera device is also effective in the field of monitoring in which subject recognition is important.
[0019]
When the switch 8 is operated to switch to the normal mode, the gain of the gain amplifier 4 is switched to the default gain by the control unit 7 and becomes 100 IRE with respect to the rated level (100%) by the auto knee processing unit 5. The point is regarded as a knee point, and it is set to 110 IRE with respect to an input 5 times the rated level (500%), and compression is performed from 100% to 500%, and an input signal exceeding 500% is clipped. Is done. That is, the image quality correction characteristic is switched to the image quality correction characteristic in the normal mode.
[0020]
When the switch 8 is operated to switch to the spot mode, the gain of the gain amplifier 4 is switched to the default gain by the control unit 7 and becomes 100 IRE with respect to the rated level (100%) by the auto knee processing unit 5. The point is regarded as a knee point, and it is set to 110 IRE with respect to an input 5 times the rated level (500%), and compression is performed from 100% to 500%, and an input signal exceeding 500% is clipped. Is done. That is, the image quality correction characteristic is switched to the same image quality correction characteristic as in the normal mode. Next, black stretch is applied by the process amplifier 6. An example of the output characteristics of the process amplifier 6 with respect to the process input is shown in FIG. Therefore, in an image obtained by taking a person taking a spotlight with the TV camera apparatus, the gradation of a dark part around the person is reproduced.
[0021]
<Second Embodiment>
The TV camera apparatus of the present embodiment has a manual switch for switching knee points, and can switch a plurality of different knee points of the auto knee processing unit 5 of FIG. 1 in accordance with the switching operation of the manual switches. I made it.
[0022]
As already described in the first embodiment, when the switch 8 in FIG. 1 is operated and switched to the backlight mode, the gain of the gain amplifier is switched to 3 times by the control unit 7 and the dynamic range is tripled. The point where the auto knee processing unit 5 becomes 80 IRE with respect to 80% is regarded as a knee point, and 110 IRE is input for 16 times (1600%) of the rated level (100%). Thus, 80% to 1600% is compressed, and input signals exceeding 1600% are clipped. The obtained image is remarkably superior to the conventional state where the bright part is completely white and nothing is reproduced, but an appropriate amount of the edge and color of the knee compression part remains.
[0023]
In this state, by operating the manual switch for knee point switching, a plurality of different knee points of the auto knee processing unit 5 of FIG. 1 can be switched, and the amount of the edge and color of the knee compression portion is controlled. be able to.
[0024]
【The invention's effect】
As described above, according to the present invention, since it is configured as described above, it is possible to further reduce the sinking of the dark portion by a predetermined switch operation, and it is possible to further reduce white stripes, The knee point can be switched.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a first embodiment of the present invention.
FIG. 2 is a diagram illustrating an example of image quality correction characteristics.
FIG. 3 is a diagram illustrating an example of an output characteristic of a process amplifier 6 with respect to a process input.
[Explanation of symbols]
1 Lens 2 CCD
3 Preamplifier 4 Gain Amplifier 5 Auto Knee Processing Unit 6 Process Amplifier 7 Control Unit 8 Switch 9 Auto Iris Control Unit 10 Iris

Claims (1)

A normal mode setting switch for setting the normal mode;
A backlight mode setting switch for setting the backlight mode;
Amplifying means for amplifying RGB signals;
The gain of the amplification means is a default gain when the normal mode is set by the normal mode setting switch, and on the other hand, a predetermined gain higher than the normal mode when the backlight mode is set by the backlight mode setting switch. Gain control means to
When the normal mode is set by the normal mode setting switch for the signal from the amplification means, a default knee process is performed. On the other hand, when the backlight mode is set by the backlight mode setting switch , -Knee processing means that lowers the point by a predetermined level from the knee point in normal mode,
An imaging system comprising: iris control means for controlling an iris according to a knee point by the knee processing means.

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