JPS62296673A - Television camera with automatic convergence adjusting function - Google Patents

Abstract

PURPOSE:To prevent the brightness level from the influence of the variation in the brightness in an other area or over entire image-pickup area by detecting a signal necessary for the diaphragm correction only within a detection area set beforehand. CONSTITUTION:In a memory, information is set as '1' for the inside of detection area and '0' for the outside of detection area. The output of a counting increased in synchronism with the scanning of an image pickup part 1 is read out as an address. The analog switch of a peak value detection part 2a turns ON/OFF corresponding to the information in '1'/'0' to hold the peak value of an image signal from inside an area A. On the ending of scanning for one frame, a detected peak value is outputted to a convergence correction part 4, the holding of the peak is reset to prepare for the detection of the peak value in the following frame. Thus the maximum brightness level of the image signals from inside the area A is inputted at every one frame, and convergence correcting signals are generated in accordance with thus detected levels. The setting of the area A can be easily executed beforehand from the drawing or photograph of the image pickup area by using a graphic tablet. With such a constitution, an approximately fixed brightness level can be maintained for the detection area.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention (Technical Field) The present invention provides an automatic aperture adjustment function that detects a signal necessary for aperture correction from an image signal output and automatically adjusts the aperture of an imaging unit. This relates to a television camera.

(Background Art) In conventional television cameras of this type, for example, the maximum brightness level is adjusted for the image signal for one frame obtained by the imaging section, and the aperture of the imaging section is adjusted. A necessary signal was detected, an aperture correction signal was created according to this signal, and the aperture of the imaging unit was adjusted. However, this method has the problem that when you want to use only the image information of a specific area on the screen, the aperture is adjusted depending on changes in brightness in areas other than this area, which also affects the brightness in the specific area. was there.

For example, consider a case where this type of television camera is used in an image monitoring type abnormality monitoring device. In an image monitoring type abnormality monitoring device, the input image is compared with a pre-stored reference image, the brightness difference between each pixel is determined, this brightness difference is binarized at a certain setting level, and then the brightness difference is converted to a set level. The number of pixels in which the above luminance difference occurs is counted, and when the counted value exceeds a certain set value, it is determined that there is an abnormality. For such monitoring devices,
When using a TV camera with the automatic aperture adjustment function described above, even if there is no brightness change in a specific area of the screen to be monitored, the aperture is corrected based on brightness changes that occur in other areas. As a result, there is a problem in that a brightness difference also occurs in the monitoring area, causing false alarms.

However, if a TV camera that does not have an automatic aperture adjustment function is used in such an abnormality monitoring device, there is a risk that even small changes in the amount of light will cause brightness differences across the screen, leading to the camera being judged as abnormal. Furthermore, there is a problem in that when the amount of light is low, such as on rainy days or in the evening, the contrast of the image decreases, causing false alarms or missed alarms.

(Objective of the Invention) The present invention has been made in view of the above-mentioned points, and its object is to change the brightness level in a specific area of the screen by changing the brightness level in other areas. To provide a television camera with an automatic aperture adjustment function that is not affected by changes in brightness or brightness changes in the entire imaging area.

(Disclosure of the Invention) As shown in FIG. 1, the television camera with an automatic aperture adjustment function according to the present invention includes an imaging section 1 that can perform aperture correction using an aperture correction signal, and A signal detection unit 2 that detects signals necessary for aperture correction from the image signals obtained
, a detection area setting section 3 that sets a detection area in which signal detection is performed by the signal detection section 2, and an aperture correction section that outputs an aperture correction signal to the imaging section 1 according to the detection signal obtained by the signal detection section 2. 4.

FIG. 2 is an explanatory diagram of the operation of the present invention. In the figure, the scene shown within the solid line frame B is an image of the imaging area obtained by the imaging section 1. Furthermore, a frame indicated by a broken line indicates a detection area A set by the detection area setting section 3. In the present invention, since the signal necessary for aperture correction is detected only within this detection area A, it is not affected by brightness changes outside the detection area, and Since the aperture is adjusted in response to changes in brightness, it is possible to maintain a substantially constant brightness level within the detection area. Therefore, if used in an image monitoring type abnormality monitoring device or the like, detection reliability will be dramatically improved.

Preferred embodiments of the present invention will be described below with reference to the drawings.

K1 Salmon FIG. 3 is a block diagram of one embodiment of the present invention.

In this embodiment, the signal detection section is a peak value detection section 2a that detects the maximum brightness level within the detection area. The peak value detection section 2a has a peak hold circuit for holding the peak value of the image signal output from the imaging section 1. For example, an image signal output from the imaging section 1 is input to this peak hold circuit via an analog switch.

The detection area setting unit 3 has a built-in image memory, and data is set in this image memory so that, for example, the inside of the detection area A shown in FIG. 2 is "]" and the outside is 0°'. has been done. The data in the image memory is sequentially read out using the output of a counter that is incremented in synchronization with screen scanning in the imaging section 1 as an address. Therefore, while the imaging unit 1 is scanning within the detection area A, the data of 1"' is displayed, and while the imaging unit 1 is scanning outside the detection area A, the data of 0° is displayed by the detection area setting unit 1. is output from. this"
The analog switch of the peak value detection section 2a is turned on/off according to the data of 1-"O". Therefore, the peak hold circuit in the peak value detection section 2a holds the peak value of the image signal within the detection area A. When one frame of scanning is completed, the detected peak value is output to the aperture correction section 4, and the peak hold circuit is reset to prepare for peak value detection of the next frame. In this way, the maximum brightness level of the image signal in the detection area A is input to the aperture correction section 4 for each frame, and the aperture correction signal for the imaging section 1 is created according to the maximum brightness level.

The detection area setting section 4 sets the detection area in advance by using a graphic tablet, etc. from a diagram of the imaging area.
This can be easily done using.

Further, in the case where a CRT for displaying image signal output is connected, a detection area may be set using a light pen, a cursor, etc. without looking at the displayed contents.

KW example-? FIG. 4 is a block diagram of another embodiment of the present invention. In this embodiment, the signal detection section is an integral value detection section 2b that detects the average luminance level within the detection area. In this embodiment, since the luminance level within the detection area is integrated in this way and the aperture correction is performed based on the average luminance level within the detection area, it is possible to prevent small light emitters or reflective objects from occurring within the detection area. Even if the brightness exists, the aperture correction can be performed based on the average brightness level without being affected much.

In addition, as an example of application of the present invention, the brightness level within the detection area may be made constant by performing gain correction of the image signal amplifying section in the imaging section 1 according to the peak value or integral value of the image signal within the detection area. Conceivable.

(Effects of the Invention) According to the present invention, in a television camera with an automatic aperture adjustment function, the detection of signals necessary for aperture correction is performed only within a preset detection area. As a result, it is not affected by brightness changes outside the detection area, and since the aperture is adjusted in response to brightness changes within the detection area, it is possible to maintain a constant brightness level within the detection area. It has the effect of being able to maintain

[Brief explanation of drawings]

Figure 1 is a claim correspondence diagram showing the basic configuration of the present invention, Figure 2 is a claim correspondence diagram showing the basic configuration of the present invention.
3 is a block diagram showing one embodiment of the present invention, and FIG. 4 is a block diagram showing another embodiment of the present invention. 1 is an imaging section, 2 is a signal detection section, 2a is a peak value detection section,
2b is an integral value detection section, 3 is an aperture correction section, and 4 is a detection area setting section.

Claims (3)

[Claims] (1) An imaging unit capable of aperture correction using an aperture correction signal;
a signal detection unit that detects a signal necessary for aperture correction from an image signal obtained by the imaging unit; a detection area setting unit that sets a detection area in which signal detection is performed by the signal detection unit;
A television camera with an automatic aperture adjustment function, comprising: an aperture correction section that outputs an aperture correction signal to an imaging section in accordance with a detection signal obtained by the signal detection section. (2) The television camera according to claim 1, wherein the signal detection section is a peak value detection section that detects the maximum brightness level within the detection area. (3) A television camera with an automatic aperture adjustment function according to claim 1, wherein the signal detection section is an integral value detection section that detects an average brightness level within a detection area.