JPS5822975A - Correlation picture tracking device - Google Patents

Abstract

PURPOSE:To input a target picture into the center of a reference window exactly and automatically in the beginning of tracking, and also to prevent a cumulative shift in the course of tracking, by switching and using an ROM in which a reference picture is written in advance, and an RAM which is capable of freely updating the reference picture. CONSTITUTION:In the beginning of tracking, a reference picture from an ROM 15, passing through a switching circuit 16 is set to a reference position of a reference window, a correlation operation against a target picture from an image pickup sensor 5, a reference window 9 and a picture data memory 12 is executed by a correlation operating circuit 13, and the target picture is inputted into around the center of the reference window even in case of a high speed target. Subsequently, when a switch 16 is switched, tracking is executed in accordance with the reference picture which is updated and written in order in an RAM 11, and as a result of operation by the circuit 13, when the correlativity drops, a position shift is corrected again in accordance with correlation against contents of the ROM 15. In this way, in the beginning of tracking, the reference picture is inputted into the center of the reference window exactly and automatically, and also the cumulative position shift in the course of tracking is prevented.

Description

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

In the conventional device, in the diagram showing the relationship between the target and the image shown in FIG. 1, the target (
A reference window is initially set so as to surround 2), and the signals surrounded by this reference window are stored and used as a reference image. From then on, the image surrounded by calculation window (3) and the reference image are A correlation calculation is performed between the images, and the image position that most closely matches the reference image is detected from among the images surrounded by the calculation window.
(The target tracking function was obtained by controlling the servo mount to which the imaging device was connected so that this position vector measured from the center of 41 converged to zero.

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, in which the image signal of the image sensor (5) is manually inputted to an analog-to-digital converter (71K) to obtain a digital image signal (8). (5) is supplied with a synchronization signal from the synchronization signal generation circuit (6).This synchronization signal is used for synchronizing operations in each part of the correlation tracking device in addition to the image sensor (5). The signal is sent to the reference window (shown in Figure 1) by the reference and calculation window setting circuit (9)
1), the image corresponding to the calculation window (3) is cut out.

The image within the reference window at a specific point in time is stored in the reference image memory 0υ by the switching circuit O1.

The image within the calculation window is stored in the image data memory a, and the correlation calculation circuit α3 performs a correlation calculation between the image in the reference image memory 0υ and the image data memo. Note that the reference image memory (Ill
, image data memory α are each readable/writable memories. The output of the correlation calculation circuit 03 is manually inputted to the matching position determination circuit α4, which evaluates the correlation value and determines the necessity of setting the next calculation window or updating the reference window. However, due to relative movement with the target, the target image may be enlarged, reduced, or
Or, if a clear alignment position cannot be obtained due to turning, the reference image captured at the beginning can be rewritten,
The image surrounded by the reference window centered at the current alignment position is stored again as a new reference image, and the correlation calculation between this reference image and the image surrounded by the calculation window at the successive point in time is performed again. However, in general, when updating the reference image, 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. Not only does this have the disadvantage that tracking becomes impossible as the target moves forward, but it is also extremely difficult to capture the target image at the approximate center of the reference window in the initial stage if the target is making high-speed turning movements. was there.

The present invention has been devised to eliminate these drawbacks.A representative reference image is stored in advance in a read-only memory, and correlation with the reference image stored in the read-only memory is performed at a necessary time. By using the position as the standard position of the reference window when storing the reference image, it is possible to automatically capture the target image at the approximate center of the reference window at the initial stage of tracking, and the In updating the reference image, the shift of the J target image from the center of the reference window is prevented from accumulating. 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,
The signal from the image sensor (5) is the reference image read/write memo I
The operation is the same until it is stored in J fJυ and the image data memory (I■).

However, since the target image assumed at the initial point of tracking or during tracking is stored in the reference image read-only memory so as to be located at the center of the reference image, switching circuit a is switched to the reference image at the initial point of tracking. The output of the read-only memory r1!9 is switched to the input of the correlation calculation circuit 0, and a reference window is automatically set approximately at the center of the target to be tracked.

In addition, the image correlation decreases during tracking, and the switching circuit (II
), the reference image read/write memory (11) is updated, and even if the next calculation window is set by the correlation calculation circuit 0 and matching position judgment circuit a4, the image correlation continues to be low and the matching position judgment circuit also matches at 4. If the position cannot be determined, the correlation calculation circuit aJ uses the contents of the reference image read-only memory α9 again using the switching circuit Oe to manually calculate the correlation with the target image assumed during tracking. Perform alignment position determination.

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 black data storage circuit are stored in the current image. When updating to an image signal surrounded by a reference window, the reference window is automatically assumed to be approximately at the center of the target, so unlike conventional devices, tracking errors accumulate each time the reference data is updated. tracking will not become impossible.

Therefore, not only is high-speed operation possible, but
In particular, performance is significantly improved when tracking a target that is making high-speed turning movements.

In addition, although 9 and above have described the case where image correlation calculation is performed in which the spread is two-dimensional, the present invention is not limited to this.
The present invention can also be applied to the case where a correlation calculation is performed on an image whose spread is one-dimensional.

[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 a reference window, (2)
is a target, (3) is a calculation window, (4) is an image, (5) is an image sensor, and (6) is a synchronization signal generation circuit. (7) is an analog-digital converter, (8) is a digital image signal, (9) is a reference and calculation window setting circuit, 01 is a switching circuit, aυ is a reference image memory, (13I11; is an image data memory, (II is a correlation calculation circuit, 04 is a matching position judgment circuit, and a!9 is a memo for reading the reference image!j
, (1 is a switching circuit. In the drawings, the same or corresponding parts are designated by the same reference numerals.

Claims (1)

[Claims] A signal having a two-dimensional spread surrounded by a reference window set within one image is stored in a reference image storage circuit, and this signal and the two-dimensional spread within the above image and subsequent images are stored. Correlation calculation is performed between the signals in each image, and 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. In image tracking equipment. A correlated image tracking device characterized in that the reference image storage circuit is equipped with both a read-only memory in which a 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. .