JPS6157756B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a correlated image tracking device characterized by automatically capturing a target image at the center of a reference window.

In the conventional device, in the diagram showing the relationship between the target and the screen shown in FIG. 1, a reference window is manually set in the initial field so that the target 2 is surrounded approximately at the center of the reference window 1, and the target 2 is surrounded by the reference window. From the next field onward, a correlation calculation is performed between the image surrounded by the calculation window 3 and the reference image, and the image position that most matches the reference image is stored in the calculation window. The servo mount on which the imaging device is mounted is controlled so that this position vector found from the image surrounded by was being carried out. In addition, if a clear alignment position cannot be obtained because the target image expands, shrinks, or rotates due to target movement, the reference image captured in the initial field is deleted and the reference image is centered at the current alignment position. The image surrounded by the window is stored again and used as a new reference image, and the correlation calculation between this reference image and the image surrounded by the calculation window in the continuous field is performed again to continue tracking. However, in general, when the reference image is updated, the target image is shifted from the center of the reference window by the tracking error, so each time the reference image is updated, the target moves away from the center of the reference window, making tracking impossible. In addition, it is extremely difficult to manually capture the target image approximately at the center of the reference window in the initial field when the target is moving at a high angular velocity.

In order to eliminate these drawbacks, the present invention calculates the center of gravity of an image surrounded by a calculation window, and uses this position as the center of the reference window when storing the reference image. In this case, the target image is not only automatically captured at approximately the center of the reference window, but also the reference image is updated during tracking so that the deviation of the target image from the center of the reference window does not accumulate. Hereinafter, a detailed explanation will be given step by step.

FIG. 2 is a diagram showing the configuration of an embodiment of the present invention, in which a video signal 6 output from the imager 5 is converted into a digital image signal (hereinafter referred to as an image signal) by an analog-to-digital converter 7. Converted to 8. In the initial field, switches 9 and 1
0 terminal A is connected to terminal 1. Calculation window position signal 12 outputted by calculation window initial position setting circuit 11
However, the calculation window position determination circuit 1 of the calculation window setting circuit 13
4, and the initial position of the calculation window is determined.
Further, the calculation window width signal 16 output from the calculation window initial width setting circuit 15 is supplied to the calculation window width determination circuit 17, and the initial width of the calculation window is determined. The image signal cut out by the calculation window whose initial position and initial width are determined is temporarily stored in the calculation data storage circuit 18, and is also supplied to the maximum value/minimum value detection circuit 19 and the binarization circuit 20. is supplied to the binary image signal 21 with the geometric mean of the maximum value and minimum value as the threshold
is converted to This binary image signal is supplied to a center of gravity calculation circuit 22 and an area measurement circuit 23, and a reference window initial position signal 24 and a reference window initial width signal 25 are calculated and output from each.

In the second field, the terminals A of the switches 9 and 10 are connected to the terminals 1 and 2, respectively, the position of the arithmetic window takes the initial value again, and the magnitude remains the initial value in the continuing field. Fixed. Also,
The terminals B of the switches 26 and 27 are connected to the terminal 1, respectively, so that the reference window initial position signal 24 and the reference window initial width signal 25 are sent to the reference window position determining circuit 28 and the reference window width setting circuit 29, respectively. supplied,
The reference window setting circuit 30 initializes the position and size of the reference window.

The image signals surrounded by the calculation window set in this way and the reference window are each stored in the calculation data storage circuit 1.
8 and the reference data storage circuit 31, and upon being sequentially read out, a correlation calculation between the two is executed in the correlation calculation circuit 32. This calculation result is supplied to the matching position determination circuit 33, and the position of the image that most matches the image surrounded by the reference window is determined from among the images surrounded by the calculation window.

In the third field and subsequent fields, terminals A of switchers 9 and 10 are connected to terminal 2, so that the center of the calculation window is set at the matching position of the previous field, and the size is set to the initial value. Continue to take. Furthermore, by connecting the terminals B of the switches 26 and 27 to the terminal 2, the reference window is centered at the matching position of the front field, and the size is as follows.
It continues to take the initial value set in the second field.

Further, the image signal stored in the calculation data storage circuit 18 in the previous field is replaced with the image signal surrounded by the calculation window in the current field, and the reference data storage circuit 31 has the image signal stored in the calculation data storage circuit 18 in the current field. Image signals stored in are saved. Then, similarly to the second field, a correlation calculation between both image signals is performed, and the center of the calculation window and reference window of the next field is set at the matching position of both images. In addition, the imager 5 is adjusted so that the alignment position measured from the center of the optical axis on the screen converges to zero.
By driving the servo mount 34 on which the target is mounted, the target is continuously tracked.

Note that if the target rotates, expands, or contracts within the screen, and a clear matching position cannot be obtained from the correlation calculation results, making it impossible to track the target, the above-mentioned second field will be returned to the state of
That is, the position of the calculation window is returned to the initial position. Further, the position and size of the reference window are re-determined by the reference window initial position signal 24 and the reference window initial width signal in the previous field, respectively, and the reference data is stored in the image signal surrounded by the current reference window. circuit 3
The contents of 1 are updated. Then, a correlation calculation is performed between this updated image signal and the image signal surrounded by the current calculation window, and a matching position is found again, so that tracking of the target is continued.

As described above, according to the present invention, in the initial field, the center and size of the target are automatically measured within the calculation window in which the rough center position is initially set, and the spread of the target is measured automatically. A reference window of a size suitable for the target is automatically set approximately at the center of the target, so there is no need to finely adjust the position and size of the reference window to match the target, unlike with conventional devices.
Therefore, not only is high-speed operation possible, but the operation becomes extremely easy, especially when tracking a target moving at a high angular velocity. Furthermore, in the present invention, when updating the contents of the reference data storage circuit to an image signal surrounded by a reference window in the current field, a reference data storage circuit whose size is compatible with the spread of the target surrounded by the calculation window is used. Since the window is set approximately at the center of the target, tracking errors do not accumulate every time the reference data is updated and tracking becomes impossible, unlike in conventional devices.

Although the above description has been made regarding the case where the correlation calculation is performed on an image whose spread is two-dimensional, the present invention is not limited to this, and can also be applied to the case where the correlation calculation is performed on an image whose spread is one-dimensional. can.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship between a target and a screen, and FIG. 2 is a diagram showing the configuration of an embodiment of the present invention.
1 is the reference window, 2 is the target, 3 is the calculation window, 4 is the screen,
5 is an image pickup device, 6 is a video signal, 7 is an analog-to-digital converter, 8 is a digital image signal, 9 and 10 are switching devices, 11 is a calculation window initial position setting circuit, 12 is a calculation window position signal, and 13 is a calculation 14 is a calculation window position determining circuit; 15 is a calculation window initial width setting circuit; 16 is a calculation window width signal; 17 is a calculation window width determination circuit; 18 is a calculation data storage circuit; 19 is a maximum value/window width setting circuit;
Minimum value detection circuit, 20 is a binarization circuit, 21 is a binary image signal, 22 is a center of gravity calculation circuit, 23 is an area measurement circuit, 24 is a reference window initial position signal, 25 is a reference window initial width signal, 26, 27 is a switch, 28 is a reference window position determining circuit, 29 is a reference window width setting circuit, 30
31 is a reference window setting circuit; 31 is a reference data storage circuit;
32 is a correlation calculation circuit, 33 is a matching position determination circuit,
34 is a servo stand.

Claims (1)

[Claims] 1. Store an image with a two-dimensional spread surrounded by a reference window set in one screen in a memory circuit,
A correlation calculation is performed between this image and the above-mentioned screen and images with a two-dimensional spread within the continuous screen, and the image position that most closely matches the image surrounded by the reference window is found among the images within each of the above-mentioned screens. Find from
In a correlated image tracking device that uses these image positions as tracking points in each screen, the center of gravity of the binary image of the images in one screen is the initial center position of the reference window,
By determining the initial width of the reference window according to the area of the binary image, the reference window can be automatically initialized approximately at the center of the target to be tracked, and the initial size of the reference window can be adjusted. A correlation image tracking device characterized in that it is adapted to the size of a target.