JPS6159039B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for tracking a subject using a television camera, and in particular detects the difference in brightness between the subject and the background, and detects the difference in brightness between the subject and the background. This relates to tracking correction of the position of a television camera so that it is centered.

A television camera is used to point at the subject,
If the subject moves, it is necessary to aim the television camera accordingly. but,
Depending on the moving speed of the subject and the degree of zooming, it may be extremely difficult for a person to do this, and there are problems such as significant fatigue when tracking a subject that moves frequently. .

On the other hand, in order to deal with such conventional inconveniences,
An oscillator is attached to or carried by the subject to be tracked, the signal emitted by the oscillator is received by a receiver on the television camera, and the television camera is automatically deflected to track the subject. Various tracking devices have been proposed. However, this type of tracking device has the inconvenience of having to attach or carry the oscillator to a moving object or person. The drawback is that the tracking device is useless. In addition, tracking devices include methods that store the video signal from a television camera using a frame memory, etc., and compare this with the video signal of the previous frame to detect a moving subject, and methods that use a computer to check patterns. However, in order to realize this, the electric circuit and mechanism of the device become complicated, resulting in high cost.

The present invention solves such conventional problems, and in particular, detects the difference in brightness between the subject and the background, calculates the center of the area of only the subject from the detection signal, and uses the calculated control signal to The purpose is to easily automatically track a subject by aiming a television camera at the center of the subject.

To achieve this objective, the present invention provides means for vertically or horizontally deflecting a television camera, means for detecting a signal whose brightness is particularly higher than the signal from the television camera, and a horizontal Alternatively, means for detecting the vertical center and means for aligning the vertical center with the center of the television screen are provided.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a block circuit of a subject tracking device according to the present invention. Reference numeral 1 denotes a video camera, which is installed on a pan-tilt table 2 for deflecting the video camera in vertical and horizontal directions. A base clamp circuit 4 for TV signals is connected to the video camera 1 via a preamplifier 3, and a slicer 6 is further connected to this via a gate circuit 5 that gates the TV signal using a horizontal synchronization signal and a vertical synchronization signal. ing. This slicer 6 extracts television signals having a predetermined level or higher. A low-pass filter 7 is connected to this slicer 6, and removes a minute area surrounded by the signal waveform from the television signal having a predetermined level or higher. A comparator 9 is connected to this slicer 6 via a peak clamp circuit 8, which creates a signal that fixes the output signal from the slicer 6 at an appropriate peak level, and also changes the overall brightness of the subject and background. Also, the output of the comparator 9 is kept unchanged.

On the other hand, on the output side of the base clamp circuit 4, a horizontal synchronization separation circuit 10 and a vertical synchronization separation circuit 1 are provided.
1 is connected to separate horizontal and vertical synchronizing signals from the television signal with a fixed base level, and these synchronizing signals drive the next monomulti circuits 12 and 13. The above-mentioned gate circuit 5 is connected to the monomulti circuits 12 and 13, and time function generators 14 and 15 are connected to the monomulticircuits 12 and 13, respectively. A functional pulse is now formed. The time function generators 14 and 15 are connected to gate circuits 16 and 17 that gate the time function pulses using the output pulses of the comparator 9, and to the gate circuits 16 and 17 are integrated circuits 18 and 17 for gated output pulses. 19 and division circuits 20 and 21 are connected one after another. The division circuits 20 and 21 divide the integrated output signal by a signal obtained by integrating the output pulse of the comparator 9 in the integration circuit 22. Further, gain control circuits 23 and 24 are connected to this division circuit 20.
The servo gain of the divided output signal is controlled by the zoom control signal to be constant, and the output signals of the gain control circuits 23 and 24 are sent to the drive device of the pan-tilt table 2 through the servo amplifiers 25 and 26. It will be done.

A video camera subject tracking device having such a configuration uses a servo amplifier 2 to transmit an area center signal of the subject.
5 and 26 to the pan/tilt table 2, which functions to control the subject so that it is always in the center of the television screen.

Next, the specific operation will be explained step by step.

FIG. 2 shows a television image 28 of a subject appearing on a television screen 27, and FIG. 3a shows a horizontal television signal waveform _S1 of a 1H period obtained when the central part of the image is scanned in the horizontal direction. Note that the method of detecting the center of the television image by extracting horizontal and vertical signals of the television screen 27 can be realized with the same system, so here we will use 1H.
A description will be given below of what processes the horizontal television signal of the period.

First, a horizontal television signal from which a television image 28 as shown in FIG. 2 is obtained is supplied to a base clamp circuit 4 via a preamplifier 3, and changes in the DC average level are suppressed when passing through a capacitor coupling circuit. The base level is clamped to prevent this from happening. This base-clamped television signal is supplied to the horizontal synchronization separation circuit 10, and a horizontal synchronization signal _S2 is extracted as shown in FIG. 3b. Note that this horizontal synchronization signal _S2 is shown inverted for convenience of explanation. This horizontal synchronizing signal S ₁ is supplied to the monomulti circuit 12 . Here, using the horizontal synchronizing signal S ₂ as a reference, first, the pulse S ₃ shown in FIG.
With this pulse S ₃ as a reference, the pulse
S ₄ is made as shown in Figure 3d. The time widths of these pulses S ₃ and S ₄ regulate the target area of the television signal, and the television signal within this regulation range is gated in the gate circuit 5 . The television signal _S5 output in this way is shown in Figure 3e.
It becomes as shown in . Subsequently, this television signal _S5 is input to the slicer 6, and is sliced at a predetermined slice level a.
The following signals are not detected, and only the upper waveform remains, like the television signal S ₆ shown in FIG. 3f.
This television signal S ₆ is then applied to a low-pass filter 7 and converted to the size of the area enclosed by the signal waveform to obtain a television signal S ₇ as shown in FIG. 3g.
This is to specify only the subject to be tracked, such as tracking only a tennis player wearing a white shirt. Additionally, this TV signal
_S7 is added to the peak clamp circuit 8, and clamps the peak level at an appropriate level where the brightness is considered to be the highest. Therefore, even if the overall brightness including the subject and background changes, the output side The output signal _S8 from the output side of the connected comparator 9 is fixed so as not to change as shown in FIG. 3h.
Note that the output signal of the comparator 9 is set to a value approximately 10% lower than the peak clamp level. The signals S ₈ thus obtained are respectively applied to gate circuits 16 . On the other hand, in the time function generator 14, a sawtooth pulse _S9 having a certain tendency is formed with respect to _the pulse _S4 as shown in FIG. It is compared whether there is an output signal _S8 of the comparator 9, and the output signal S8 of the comparator 9 is compared.
A pulse _S10 is obtained in which the position of the output signal _S8 is represented by a voltage level as shown in FIG. In other words, the magnitude of the level is determined by which slope of the pulse _S9 the output signal _S8 is located at. This output pulse S ₁₀ is then smoothed by an integration circuit 18 that includes a CR time constant, etc., and the smoothed output signal is applied to a division circuit 20 where it is divided by the signal obtained by integrating the output signal S ₈ of the comparator 9. and as an error signal of the center of the television image with respect to the center of the horizontal television signal, via the gain control circuit 23,
The signal is applied to the servo amplifier 25, and the pan/tilt table 2 is driven in the horizontal direction by a value corresponding to the signal.

In addition, in the above embodiment, the direction control of the video camera was specifically described as controlling only the horizontal direction, but the control in the vertical direction is also exactly the same as above, and the detection of the center position of the subject in the vertical direction is performed in the vertical direction. This is performed using the output signal of the synchronization separation circuit 11 as a reference. And when you put these two together,
The position of the pan-tilt table 2 is controlled not only in the horizontal direction but also in the vertical direction. It should be noted that since the vertical synchronization signal appears repeatedly at approximately 1/60 Hz, the cycle is longer than that of the horizontal synchronization signal, and therefore the position of the comparator 9 can be detected accurately and easily. In addition, as shown in Figure 2, a high brightness light source or object 2 may be placed at a position corresponding to the periphery of the TV screen.
9, the resulting TV signal level becomes abnormally high, and this signal is detected even after passing through the slicer 6, and the pan/tilt table is moved so that the TV camera is moved in the direction of the light source or object. 2 may malfunction. Therefore, by providing a muting circuit that allows the peripheral area (hatched area) of the TV screen that includes the light source or object to be captured, but does not sense the light from that peripheral area.
A television image of only the tracked object can be obtained without erroneously detecting the light source or the center of the object. On the other hand, this can also be realized by electrically detecting the range in which the television camera can be deflected using a volume mounted on the pan/tilt table 2. In other words, when the television camera moves outside the operating setting range, the voltage detected by the volume activates the muting circuit, causing the television camera to wait at that position, and then canceling the muting when the object enters the tracking area. You can also do this by doing something like this.

As described above, the present invention includes a deflecting means for deflecting a television camera in the horizontal or vertical direction, and slicing and integrating the television signal supplied from the television camera, and converting the resulting output into a reference level. A detection means for detecting that the brightness of the object to be tracked and the area of the object reach a predetermined amount by comparing the time function pulse obtained in relation to the synchronization signal separated from the television signal. center error detection means for obtaining an error signal at the center of the image by integrating and dividing each of the output pulse gated by the output of the detection means and the output of the detection means; and a control means for controlling the television camera so that the center of the subject coincides with a predetermined position on the screen. At the same time, the area center of the bright object is detected using the signal obtained from the synchronization signal as a reference, and the area center generated by the movement of the TV camera is made to match the image center on the screen in a tracking manner. By controlling the television camera, tracking of the subject is realized. Therefore, there is no need for constant framing operations, which is useful for tennis clinics and the like. As described above, the circuit configuration is simple and can be obtained at low cost, so it is extremely useful in practice. In addition, since the luminance detection of the above-mentioned object is performed using a one-field average, there are fewer malfunctions, and since the area center information of the tracked object is fielded back, it is not affected by hand movements when the tracked object is a human etc. There are advantages. Furthermore, when a color video camera is used, by combining it with a hue discrimination circuit, it becomes possible to selectively track a plurality of objects individually.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a block circuit diagram of a subject tracking device according to the present invention;
FIG. 2 is an explanatory diagram of a television image, and FIGS. 3 a to 3 j are signal waveform diagrams of various parts of the block circuit. 1...TV camera, 2...Pan-tilt stand, 6...Slicer, 9...Comparator, 14, 15...Time function generator, 18, 19, 22...Integrator circuit, 2
0, 21...Division circuit, 25, 26...Servo amplifier.

Claims (1)

[Claims] 1. Deflection means for deflecting a television camera horizontally or vertically; slicing and integrating a television signal supplied from the television camera and comparing the resulting output with a reference level; detecting means for detecting that the brightness of the object to be tracked and the area of the object reach a predetermined amount; and detecting the time function pulse obtained in relation to the synchronization signal separated from the television signal. center error detection means for obtaining an error signal at the center of the image by integrating and dividing each of the output pulse gated by the means output and the output of the detection means; and controlling the deflection means using the error signal. hand,
A device for tracking a subject using a television camera, comprising: control means for controlling the television camera so that the center of the subject coincides with a predetermined position on the screen.