JPS6326355B2 - - 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 apparatus, in the diagram shown in FIG. 1 showing the relationship between the target and the image, a reference window is initially set so that the target 2 is surrounded approximately at the center of the reference window 1. The signal is stored and used as a reference image, and thereafter, a correlation calculation is performed between the image surrounded by the calculation window 3 and the reference image.
A servo mount to which the imaging device is connected so that the image position that most matches the reference image is detected from among the images surrounded by the calculation window, and this position vector from the center of the image 4 converges to zero. was controlled to obtain target tracking capabilities.

The operation of the conventional device will be explained in more detail with reference to FIG. FIG. 2 is a diagram showing the configuration of a conventional correlation tracking device. An image signal from an image sensor 5 is input to an analog-to-digital converter 7, and a digital image signal 8 is obtained. On the other hand, a synchronization signal is supplied to the image sensor 5 from a synchronization signal generation circuit 6 . This synchronization signal is used for synchronization operations in various parts of the correlation tracking device in addition to the image sensor 5. or,
The digital image signal is sent to the reference and calculation window setting circuit 9.
The image corresponding to the reference window 1 and calculation window 3 shown in FIG.
At the same time, the image within the calculation window is stored in the image data memory 12, and the correlation calculation circuit 13 performs a correlation calculation between the image in the reference image memory 11 and the image in the image data memory 12. . Note that each of the reference image memory 11 and the image data memory 12 is a readable/writable memory. The output of the correlation calculation circuit 13 is input to the matching position determination circuit 14, which evaluates the correlation value and determines the necessity of setting the next calculation window or updating the reference window. However, if a clear alignment position cannot be obtained because the target image expands, shrinks, or rotates due to relative movement with the target, the initially captured reference image is rewritten and the reference image is centered at the current alignment position. The image surrounded by the window was 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 at the continuing point in time was performed again, and tracking was continued. but,
Generally, when updating the reference image, the target image is shifted from the center of the reference window by the tracking error, so
Not only does the target move away from the center of the reference window each time the reference image is updated, making tracking impossible, but capturing the target image at approximately the center of the reference window in the initial stage means that the target is moving at high speed. However, there were drawbacks that made it extremely difficult.

This invention was devised in order to eliminate these drawbacks, and involves storing a representative reference image in advance in a read-only memory, and then calculating the correlation position with the reference image stored in the read-only memory at a necessary point in time. By using this as the reference position of the reference window when storing the reference image, it is possible to automatically capture the target image almost at the center of the reference window, especially at the beginning of tracking, and In updating the reference image, the aim is to prevent the accumulation of deviations of the target image from the center of the reference window. This will be explained in detail below with reference to FIG. FIG. 3 is a diagram showing the configuration of an embodiment according to the present invention, and the operation is the same until the signal from the image sensor 5 is stored in the reference image read/write memory 11 and the image data memory 12.

However, since the target image assumed at the initial point of tracking or in the middle of tracking is stored in the reference image read-only memory so as to be located at the center of the reference image, the switching circuit 16
The output of the reference image read-only memory 15 is switched to the input of the correlation calculation circuit 13, and the reference window is automatically set approximately at the center of the target to be tracked.

Also, the image correlation decreases during tracking, the switching circuit 10 is closed, the reference image read/write memory 11 is updated, and the correlation calculation circuit 13 and matching position determination circuit 1
4, even if the next calculation window is set, if the image correlation is still low and the matching position determination circuit 14 cannot determine the matching position, the switching circuit 16 again transfers the contents of the reference image read-only memory 15 to the correlation calculation circuit. By inputting 13, a correlation calculation with a target image assumed during tracking is performed in advance to determine a matching position.

As described above, according to the present invention, in the initial stage of tracking, it is possible to automatically set the reference window approximately at the center of the target to be tracked, and the contents of the reference data storage circuit can be set to the current image. When updating to an image signal surrounded by a reference window, the reference window is approximately
Since the center of the target is automatically assumed, unlike conventional devices, tracking errors do not accumulate every time the reference data is updated and tracking becomes impossible.

Therefore, not only is high-speed operation possible, but the performance is significantly improved, especially when tracking a target that is turning at high speed.

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 an image, FIG. 2 is a diagram showing the configuration of a conventional correlation tracking device, and FIG. 3 is a diagram showing the configuration of an embodiment of the present invention.
is the reference window, 2 is the target, 3 is the calculation window, 4 is the image, 5
is an image sensor, 6 is a synchronization signal generation circuit, 7 is an analog-to-digital converter, 8 is a digital image signal,
9 is a reference and calculation window setting circuit; 10 is a switching circuit;
11 is a reference image memory, 12 is an image data memory, 13 is a correlation calculation unit circuit, 14 is a matching position determination circuit, 15 is a reference image read-only memory, 16
is a switching circuit. Note that the same or corresponding parts in the figures are indicated by the same reference numerals.

Claims (1)

[Claims] 1 A signal with a two-dimensional spread surrounded by a reference window set within one image is stored in a reference image storage circuit, and a signal with a two-dimensional spread within the above image and subsequent images is stored. In the correlated image tracking device, the image position that most closely matches the image surrounded by the reference window is found from among the signals in each of the above images, and these image positions are used as the tracking points in each image. The correlated image is characterized in that the reference image storage circuit is equipped with both a read-only memory in which the reference image is stored in advance and a memory that can be read and written so that the reference image can be rewritten during tracking. Tracking device.