KR100202138B1 - Automatic threshold control method and circuit for image tracing apparatus - Google Patents

Abstract

In particular, the image tracker is an automatic threshold hold control circuit that automatically adjusts the threshold value by extracting a part of the image signal when the target and the background are separated to track a specific target included in the image signal captured by the TV camera. It is about.

In the image tracking, the threshold hold value for separating the target and the background of the image signal is automatically set through the differential pulse obtained from the original image signal, so the threshold hold value that is set without an additional circuit is optimally adjusted. can do.

Description

Automatic Threshold Hold Control Circuit and Method of Image Tracker

1 is a block diagram of a conventional image tracking system.

2 is a waveform diagram of operating parts of FIG.

3 is a block diagram of an image tracking system according to the present invention.

4 is a detailed circuit diagram of the automatic threshold hold control circuit 3 in FIG.

5 is an operating waveform diagram of each part of FIG.

* Explanation of symbols for main parts of the drawings

10: gain control squarer 20,50: first to second integrator

30, 60: first to second code converter 70: divider

80: route calculation circuit 40: gain control unit

The present invention relates to an image tracking system. In particular, an automatic threshold for automatically adjusting a threshold hold value by extracting a part of an image signal when separating a target and a background to track a specific target included in an image signal enhanced by a TV camera is provided. The present invention relates to a sea hold control circuit and a method.

1 is a block diagram of a conventional image tracking system.

An image as shown in FIG. 2A is captured by the TV camera 1 and output as an image signal as shown in FIG. 2A. The amplifier and the differentiator 2 for inputting the video signal output from the TV camera 1 are output as pulses like the second diagram 2c in which the edges of the target and the background are differentiated. The pulse output from the amplifier and the differentiator 2 is manually adjusted as shown in FIG. 2D by the gain control unit 3 composed of a variable resistor, and thus the threshold hold level value is adjusted in the edge pulse generator 4. The edge pulse shown in FIG. 2E will be output.

The edge pulse output from the edge pulse generator 4 is generated for each boundary portion where the target and the background are separated, and the size of the entire target is proportional to the number of pulses.

Since the edge pulse generated by the edge pulse generator 4 is input to the automatic tracking error generator 5 to generate a target position error signal, the target position shift on the screen becomes a change in the distribution of the pulse on the screen, and thus the position of the target. You can calculate it as a change.

As such, the conventional image tracker has a problem in that it is inconvenient to manually adjust the threshold hold level for separating a specific target included in the image signal from the background, and there is a problem of degrading the performance of the image tracker.

Accordingly, an object of the present invention is to provide a threshold hold control circuit and method for automatically adjusting a threshold hold level for separating a specific target of an image signal captured by a TV camera from a background in an image tracker.

It is an object of the present invention to provide a threshold hold control circuit and method for automatically adjusting a threshold hold level for separating a specific target of an image signal captured by a TV camera from a background in an image tracker.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

3 is a block diagram of an image tracking system according to the present invention, and a TV camera 1 for capturing an image and outputting an image signal, and amplifying the image signal output from the TV camera 1 to target and background. An amplifier and a differentiator 2 for differentially outputting a boundary portion and a signal differentially output from the amplifier and the differentiator 2 are inputted to output a threshold hold level value for edge detection according to the amplitude and number of the input differential image signals. An edge for generating an edge pulse with a threshold level output from the threshold control circuit 3 by inputting a differentially output signal from the threshold control circuit 3 and the amplifier and the differentiator 2 And a pulse generator 4 and an automatic tracking error generator 5 for inputting edge pulses generated by the edge pulse generator 4 to generate a target position error signal.

FIG. 4 is a detailed circuit diagram of the automatic threshold hold control circuit 3 of FIG. 3 according to the present invention. Integrating the differential image signal squared amplified in 10) during the stop section from the start section of each screen inputs the integral output first integrator 20 and the integral signal of the end portion of each screen of the output of the first integrator 20 A first integrator 30 for code conversion and output, a gain controller 40 for inputting and outputting a reference voltage for gain adjustment, and a second integrator for integrating the reference voltage whose gain is adjusted in the gain controller 40. And a second code converter 60 for sign-converting the reference voltage integrated in the second integrator 50, and between the gain control squarer 10 and the first integrator 20. It is connected to the gain control unit 40 and the second integrator 50 to display every screen of an image signal. The first and second switches SW1 and SW2, which are interlocked and switched by a start signal, are connected between the first integrator 20 and the first code converter 30 and are connected to the second integrator 50. A signal converted from the third to fourth switches SW3-SW4 and the first to second code converters 30 and 60 connected between the second code converters and interlocked and switched by the stop signal of each screen. A divider 70 for dividing the coded video signal into a coded reference voltage by inputting the respective signals, and a root calculation circuit 80 for performing a root operation on the signal divided by the divider 70. It consists of.

FIG. 5 is a diagram illustrating the operation waveforms of each part according to the present invention. An embodiment of the present invention will be described in detail with reference to FIGS.

An image as shown in FIG. 2A is captured by the TV camera 1 and output as an image signal as shown in FIG. 2A. The amplifier and the differentiator 2 for inputting the video signal output from the TV camera 1 are output as pulses like the second diagram 2c in which the edges of the target and the background are differentiated. The pulses output from the amplifier and the differentiator 2 are input to the automatic threshold control circuit 3 to automatically generate and output a threshold level according to the amplitude or number of input differential pulses. At this time, the edge pulse generator 4 for inputting the pulse output from the amplifier and the differentiator 2 generates and outputs an edge pulse by the threshold value.

The edge pulse output from the edge pulse generator 4 is generated for each boundary portion where the target and the background are separated, and the size of the entire target is proportional to the number of pulses.

Since the edge pulse generated by the edge pulse generator 4 is input to the automatic tracking error generator 5 to generate a target position error signal, the target position shift on the screen becomes a change in the distribution of the pulse on the screen and thus the position of the target. You can calculate it as a change.

The detailed operation of the automatic threshold control circuit 3 of the image tracking system operating as described above will be described with reference to FIGS. 4-5, and the differential image signal as shown in FIG. After the gain is adjusted by the resistor R1, the squarer 11 performs a square operation to output a signal as shown in FIG. 5B. In addition, the gain of the reference voltage Vf is adjusted by the gain adjuster 10 including the resistor R4 capacitor c1 diode d1.

At this time, when the first-second switch SW1-SW2 is turned on by the start signal of the video signal, that is, the start signal of each screen, the video signal output from the gain control squarer 10 and the gain control unit 40 The output reference voltage Vf is switched. Therefore, the image signal output from the gain control squarer 10 is stopped at each screen section in the first integrator 20 including the resistors R2-R3 variable resistor VR2 capacitor c2 buffer 21. Integral output during the interval. The reference voltage Vf gain-adjusted by the gain control unit 40 is integrated in the second integrator 50 including the resistors R5-R6 variable resistor VR3, the capacitor 3, and the buffer 51. . At this time, if the stop signal at the end of each screen is applied to the second-third switch SW3-SW4, the third-fourth switch SW3-SW4 is turned on, and the first integrator 20 shows the fourth diagram ( The integrated reference signal is output as shown in 4d).

Here, the output of the first integrator 50 varies in value depending on the amplitude or number of differential image signals. If the target is clearly distinguished from the background, a large amplitude pulse is generated, and a weakly generated pulse is generated. The output of the first integrator 20 becomes small.

However, the output of the second integrator 50 is determined according to the interval between the start signal and the stop signal. When the start signal and the stop signal interval are constant, the output of the second integrator 50 is always a constant value.

The video signal, such as the image of FIG. 5 (5c) integrated by the first integrator 20, is code-transformed by the first code converter 30 including the capacitor c4 operational amplifier OP1. A reference signal such as the fifth signal 5c integrated by the second integrator 50 is coded by the second code converter 60 formed of the capacitor c5 operational amplifier OP2.

The divider 70 for inputting the signals output from the first to second code converters 30 and 60 to the input terminals X1 and Y1 respectively divides the coded video signal into a coded reference signal. Will print. The signal divided by the divider 70 is automatically routed to the threshold hold value by performing a root operation on the root calculating circuit 80.

For example, when the differential image field is a, the output of the gain control squarer 10 is b, the output of the first integrator 20 is C, and the output of the second integrator 50 is d. It is as follows if shown.

KA ^Z

And if the output of the divider 7 is E do.

Therefore, if the output of the loop calculation circuit 80 is F

Becomes

Therefore, if the initial threshold hold value is set too large for a given target, excessive edge pulses are generated and the threshold hold value is increased. However, if the initial threshold hold value is set too high and the edge pulse is small, the threshold hold value can be lowered to generate an appropriate edge pulse.

As described above, since the threshold value for separating the target and the background of the image signal is automatically set according to the amplitude or number of differential pulses obtained from the original image signal in the image tracking, the threshold value is set without an additional circuit. There is an advantage that it is possible to adjust the value of she hold optimally.

Claims (2)

In the automatic threshold hold control circuit for separating a target from a background in an image tracker, a gain control squarer (10) for inputting squared amplified image signals and outputting the squared amplified outputs, A first input of an integral output signal of the integrating output first integrator 20 and an integral signal of an end portion of each screen among the outputs of the first integrator 20 for sign conversion A signal converter 30, a gain controller 40 for inputting and controlling a gain of a reference voltage, a second integrator 50 for integrating the gain-controlled reference voltage with the gain controller 40, and A second code converter 60 for converting the reference voltage integrated in the second integrator 50, and between the gain control squarer 10 and the first integrator 20 and the gain control unit 40. ) And the time of each screen of the video signal connected to the second integrator 50 The first and second switches SW1 and SW2, which are interlocked and switched by a start signal, are connected between the first integrator 20 and the first code converter 30 and are connected to the second integrator 50. A signal converted from the third to fourth switches SW3-SW4 and the first to second code converters 30 and 60 connected between the second code converters and interlocked and switched by the stop signal of each screen. And a divider 70 for dividing the coded video signal into a coded reference voltage, and a root calculation circuit 80 for performing a root operation on the signal divided by the divider 70. Circuit characterized in that. A method of automatically adjusting a threshold level for separating a target from a background in an image tracker, the method integrates squared differential image signals, converts the integrated signals when a still signal of each screen is generated, and converts a reference voltage. After integration, the code conversion is performed to divide the coded video signal into the coded reference voltage, and then route operation to automatically adjust the threshold value according to the amplitude and number of the differentiated video signals. How to.