JP3456231B2 - Subject tracking device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an object tracking device for tracking the position of a moving object in a field.

[0002]

2. Description of the Related Art As a conventional subject tracking device of this type, there is a device disclosed in Japanese Patent Laid-Open No. 61-2177, for example. In the device disclosed in this publication, the photographer manually sets the initial value of the size of the tracking visual field set in the field for performing the subject tracking calculation, and the value is included in the manually set tracking visual field. The position of the subject is tracked while moving the tracking field of view.

[0003]

However, in the above-mentioned conventional subject tracking apparatus, the size of the tracking visual field must be manually set according to the size of the subject to be tracked by the photographer. Since there was no such thing, the photographer could not concentrate on the shooting, and there was a risk of missing the photo opportunity while setting the tracking field of view.

An object of the present invention is to provide a subject tracking device which can perform initial setting of a tracking frame used for subject tracking without bothering a photographer.

[0005]

SUMMARY OF THE INVENTION According to the present invention, a field is divided into a plurality of photometric regions for photometry, the field is classified into a plurality of groups based on photometric information, and the plurality of groups are grouped. Among these, the contours of the groups existing in the vicinity of the optical axis of the photographing lens are set as the initial values of the tracking frame for subject tracking. Then, the difference between the photometric information of the photometric area belonging to the tracking frame and the photometric information of the photometric area belonging to each group, and the measurement of the photometric area overlapping between the photometric area belonging to the tracking frame and the photometric area belonging to each group. The tracking frame is moved based on the number, and the main subject is tracked in the field.

In the present invention, the tracking frame may be displayed in the scene. In addition, it outputs information about the color of the subject that exists in the scene as photometric information,
The photometric areas having similar color components may be sectioned to detect the main subject and its size, and the contour of the photometric area belonging to the section where the main subject exists may be set as the tracking frame.

[0007]

The contour of a group existing near the optical axis of the taking lens is set as an initial value of a tracking frame for tracking an object, and the photometric information of the photometric areas belonging to the tracking frame and the photometric information of the photometric areas belonging to each group are set. , And the number of photometric areas overlapping between the photometric areas belonging to the tracking frame and the photometric areas belonging to each group, the tracking frame is moved to track the main subject in the object scene.

Incidentally, in the section of means and action for solving the above-mentioned problems for explaining the constitution of the present invention, the drawings of the embodiments are used to make the present invention easy to understand. It is not limited to.

[0009]

【Example】

First Embodiment FIG. 1 is a diagram showing a first embodiment of a camera to which the subject tracking device according to the present invention is applied, and is a block diagram showing a configuration of a main part. In FIG. 1, 11 is a photometric unit,
The photometric unit 11 is a photometric device 9 as shown in FIG. 3 (see FIG. 2).
Is equipped with. The photometric element 9 has 20 pieces vertically and 12 pieces horizontally.
Forty divided elements 9a are provided, and each divided element 9a corresponds to each divided photometric area obtained by similarly dividing the object field into 240 areas. Hereinafter, as an address indicating the position of each divided photometric area, the divided photometric area at the bottom left of FIG. 3 is expressed as (1, 1) and the divided photometric area at the top right is expressed as (20, 12). As shown in FIG. 4, each dividing element 9a is further divided into three sub-dividing elements 9R, 9B, 9G, and RGB filters (not shown) are attached to each sub-dividing element 9R, 9B, 9G. ing. As a result, each of the splitting elements 9a is capable of individually photometrically measuring each of the split photometric areas in three colors of R, G, and B.

Reference numeral 12 denotes a group creating section, which is a photometry section 11
The subjects existing in the object scene are grouped based on the information for each divided photometric area output from. Details of the grouping calculation will be described later. A tracking frame setting unit 13 sets a tracking frame for subject tracking based on the output of the group creation unit 12. Details of the tracking frame setting will also be described later.

Reference numeral 14 denotes a subject tracking unit, which performs subject tracking within the field based on the information output from the photometry unit 11 and the output from the tracking frame setting unit 13. Details of the subject tracking operation will also be described later. An exposure calculation unit 15 calculates an appropriate exposure value based on the information output from the photometry unit 11 and the output of the subject tracking unit 14. An exposure control unit 16 controls an aperture and a shutter (not shown) based on the proper exposure value calculated by the exposure calculation unit 15 to expose the film.

A display unit 17 displays a tracking frame in the field based on the output of the tracking frame setting unit 13. More specifically, the display unit 17 includes an on-screen liquid crystal 10 (see FIG. 2), and the on-screen liquid crystal 10 changes the light transmittance with a voltage to display a tracking frame in the field. . The details of the display pattern of the on-screen liquid crystal 10 are shown in FIG. On-screen liquid crystal 10
Is a segment h [i, j] corresponding to each divided photometric area.
(I = 1 to 20, j = 1 to 13) and v [m, n]
(M = 1 to 21, n = 1 to 12), and each segment can be displayed independently. For example, as shown in FIG. 6, (10,6), (11,6), (10,7),
When four areas of (11, 7) are displayed as a tracking frame, h [10,6], h [11,6], h [10,
8], h [11,8], v [10,6], v [10,
7], v [12,6], and v [12,7] 8 segments may be displayed.

FIG. 2 is a block diagram showing the optical system of the camera according to this embodiment. The light flux that has passed through the taking lens 1 passes through the quick return mirror 2, the diffusion screen 3, the on-screen liquid crystal 10, the condenser lens 4, the pentaprism 5 and the eyepiece lens 6 and reaches the eye of the photographer. On the other hand, a part of the light flux diffused by the diffusing screen 3 includes a condenser lens 4, a penta prism 5,
The light reaches the above-described photometric element 9 via the photometric prism 7 and the photometric lens 8. On-screen liquid crystal 10 described above
Is arranged immediately above the diffusion screen 3 which is the focal plane, and the tracking frame can be displayed in the field screen by the above-mentioned method. Therefore, the photographer uses the photographing lens 1
You can see the object scene image from and the tracking frame at the same time.

Next, referring to the flowchart of FIG.
The operation of the camera of this embodiment will be described. The flowchart shown in FIG. 7 shows an algorithm when each unit shown in FIG. 1 is configured by one microcomputer (not shown).

(1) Grouping calculation The flowchart shown in FIG. 7 is started by half-pressing a release button (not shown). First, step S10
In 1, the photometry of the object field is performed using the photometry unit 11, and 24
R, G, and B photometric values are obtained for each of the 0 divided photometric regions. The photometric value obtained from each of the divided photometric areas is stored in a memory (not shown) of the microcomputer.

Next, in step S102, the group forming section 12 is used to perform grouping calculation of the objects based on the photometric values of the entire object field stored in the memory. Details of the grouping calculation are described in, for example, Japanese Patent Laid-Open No. 4-310930.
Since it is disclosed in detail in Japanese Patent Publication No. JP-A-2003-242, etc., its explanation will be simplified here, but the point is that the hue (what kind of color) for each of the 240 divided photometric areas is shown in a chromaticity diagram or the like. Based on the above, the divided photometric areas that are adjacent to each other are formed into one group and the divided photometric areas that are similar to each other are grouped into one group. Classify into groups. FIG. 11A shows an example of the object scene, and FIG.
FIG. 12 is a diagram showing an example in which a grouping calculation is performed on the object scene shown in FIG. Dividing element 9a corresponding to the divided photometric area in which the airplane is metered, dividing element 9a corresponding to the divided photometric area in which the clouds are metered, and dividing element corresponding to the divided photometric area in which the background sky is metered It can be understood that 9a is classified into different groups.

In step S103, the tracking frame setting unit 13
Initialize the tracking frame using. In this embodiment, of the groups obtained by the grouping calculation in step S102, the central portion of the photometric area, that is, the taking lens 1
The contour of the group to which the divided photometric areas (10, 6) near the optical axis of is belonging to is set as the initial value of the tracking frame. As an example, when the grouping is performed as shown in FIG. 8A, the group G1 to which the divided photometric area (10, 6) near the optical axis belongs is selected, and the contour of the group G1 is the initial value of the tracking frame. Is set as. When the tracking frame is set, the photometric values obtained from the divided photometric areas belonging to this tracking frame are stored in a memory (not shown) of the microcomputer.

In step S104, the tracking frame setting unit 13
The display unit 17 is used to display the tracking frame set in step S103. As described above, the display of the tracking frame is performed by lighting the corresponding segment of the on-screen liquid crystal 10, that is, the segment corresponding to the tracking frame. In a succeeding step S105, it is determined whether or not a release button (not shown) is half-pushed, and if the determination is negative, it is determined that the subject existing in the tracking frame does not meet the photographer's intention, Returning to step S101, the above operation is repeated. On the other hand, if the determination is affirmative, it is determined that the subject existing in the tracking frame is the subject to be tracked, and the program proceeds to step S106.

In step S106, step S101
The photometry of the object field is performed using the photometry unit 11 in the same manner as
R, G, and B photometric values are obtained for each of the 0 divided photometric regions. In a succeeding step S107, the subject tracking unit 14 is used to perform a subject tracking operation. The tracking operation is performed as follows.

First, of the photometric values stored in the memory of the microcomputer (not shown), from the photometric values from the divided photometric areas belonging to the tracking frame, R, G, and
The average values BVr, BVg, BVb of the photometric values of B are calculated. Next, based on the photometric values obtained in the immediately preceding step S106, the photometric values are grouped by the same method as in step S102. As a result, assuming that they are classified into N groups, for each of these N groups as well, from the photometric values from the divided photometric areas belonging to each group, the R, G, and B photometric values within the group are determined. Average values BVr [n], BVg [n], BVg [n] (hereinafter,
1 ≦ n ≦ N, where n is a natural number). And
These average values BVr, BVg, BVb and BVr
Using [n], BVg [n], and BVg [n], ΔBVc [n] as shown in the following equation (1) is calculated.

## EQU00001 ## .DELTA.BVc [n] = Abs (BVr-BVr [n]) + Abs (BVg-BVg [n]) + Abs (BVb-BVb [n]) ... (1) where the symbol Abs ( (Mathematical formula) is a function representing the absolute value of the mathematical formula in parentheses. Then, using this ΔBVc [n], G [n] as shown in the following equation (2) is calculated.

## EQU2 ## G [n] = RN [n] -k.multidot. (. DELTA.BVc [n]) (2) where RN [n] is a divided photometric area belonging to the tracking frame and a group n. This is a variable indicating the number of divided photometric areas overlapping with the divided photometric areas to which it belongs. Also,
k is a positive constant for adjusting the degree of the above-mentioned ΔBVc [n] contributing to G [n] with respect to RN, and is set to an optimum value in advance.

Then, the variable G [n] is obtained for each of the N groups obtained in the above process, and the contour of the group giving the maximum value among the N variables G [n] is newly updated. Set as a tracking frame.

For example, as described above, assume that the initial value of the tracking frame is G1 shown in FIG.
It is assumed that the subject T has moved as shown in (b). The frame shown by the dotted line in FIG. 8B is the initial value G1 of the tracking frame. Then, it is assumed that the groups G2 and G3 are newly created by the grouping calculation in step S106. Then, G [n] is calculated using the equations (1) and (2) for these groups G2 and G3, respectively.
The contour of the group with the larger value of [n] is set as a new tracking frame. In the example shown in FIG. 8B, the divided photometric areas belonging to the group G2 are included (that is, overlapped) in the divided photometric areas belonging to the initial value G1 of the tracking frame.
Therefore, the value of RN [n] is large, while the divided photometric areas belonging to the group G3 almost do not overlap with the divided photometric areas belonging to the initial value G1 of the tracking frame, so the value of RN [n] is small. If ΔBVc [n] of the groups G2 and G3 are equal, the newly set tracking frame becomes the contour of the group G2, and the position information and photometric values of all the divided photometric areas included in the group G2 serve as new tracking frame information. It is rewritten in the memory of the microcomputer. In this way, the tracking frame is set according to the movement of the subject, and the tracking frame information (position information and photometric value of the divided photometric areas belonging to the tracking frame) is rewritten one after another, so that the tracking operation of the subject is performed. Be seen.

Next, in step S108, the exposure control unit 15 is used to perform an operation of calculating an appropriate exposure value based on a well-known algorithm. In step S109, it is determined whether or not a release button (not shown) is fully pressed, and if the determination is positive, the program proceeds to step S110.
If the determination is negative, the process returns to step S106 to repeat the above operation. In step S110, the exposure control means 16 is used to perform exposure control based on the appropriate exposure value, and the film is exposed.

The result of subject tracking is obtained in step S1.
It is reflected in the exposure calculation algorithm of 05. As an example, there is an algorithm that obtains the position of the main subject from the result of subject tracking, calculates the luminance value of the portion from the position of the main subject, and calculates the proper exposure value with emphasis on this luminance value. . In addition, the camera of the present embodiment,
If a focus detection device capable of detecting focus for a plurality of focus detection areas in the field is provided, the focus detection operation should be performed based on the information of the focus detection area closest to the position of the object being tracked. Various focus detection algorithms are also possible.

Therefore, according to the present embodiment, the object fields are grouped based on the photometric information, and the initial value of the tracking frame for object tracking is set based on the grouped groups. As described above, it is not necessary for the photographer to manually set the tracking frame, and the initial setting of the appropriate tracking frame can be performed without bothering the photographer. In addition, since the object tracking is performed based on the photometric information from the photometric unit 11, it is economical without requiring an additional image sensor for tracking the object.

-Second Embodiment- In the second embodiment, the size of the tracking frame for tracking an object is fixed to realize a high-speed and highly accurate tracking operation.
The configuration of the camera of this embodiment is substantially the same as that of the above-described first embodiment, and its operation is also step S107.
Since they are substantially the same except for the above, only different parts will be described and other description will be omitted.

FIG. 9 is a diagram showing the relationship between the tracking frame G and the divided photometric areas at a certain point during the subject tracking operation. In the example shown in FIG. 9, the tracking frame G has four vertical lines indicated by thick lines.
It is set so as to form the contours of 16 divided photometric areas, that is, 16 in total × 4 in total. At this time, 1 belonging to the tracking frame G
As shown in the figure, the six divided photometric areas are numbered from 1 to 16 for distinction. Next, consider 8 kinds of tracking frames in which the tracking frame G is shifted to the left and right in the X direction, the left and right in the Y direction, and diagonally above and below the left and right by one divided photometric area, and combined with the current tracking frame. Consider 9 different tracking frames. Then, the photometric output BV [i, x] (i = R, G, B, x = 1) obtained from the tracking frame already used for the tracking calculation.
~ 16) and the photometric output BV [i, x '] (i = R, G, B, x' = 1 for each tracking frame used in the tracking calculation this time).
16) and 16) are respectively compared by the following equation (3).

## EQU00003 ## D = .SIGMA.Abs (BV [i, x] -BV [i, x ']) (3) where the symbol .SIGMA. (Sigma) is i = R, G, B, x = 1.
˜16, x ′ = 1 to 16 represents the total sum of data.
As the photometric output BV [i, x], the photometric output stored in step S103 is used when the loop of the flowchart is the first time, and the photometric output used in the previous subject tracking calculation when the loop is the second time or later. To use. On the other hand, photometric output BV
The latest photometric output obtained in step S106 immediately before is used for [i, x ']. In this way, when D is obtained for each of the nine tracking frames, the tracking frame with the smallest D is detected, this is set as a new tracking frame, and tracking frame information is stored in the memory.

As an example, the relationship between the tracking frame G and the subject T initially set in the step S103 is shown in FIG.
It is assumed that it is as shown in (a). The size of the tracking frame G at this time is 4
It is assumed that the area is composed of 4 × 4 divided photometric areas. However,
Since the size of the tracking frame is determined in step S103, it does not necessarily have to include 16 divided photometric areas. Next, it is assumed that the subject T has moved to the position shown in FIG. 10B when the program proceeds to step S107. Since the frame indicated by a dotted line as the previous tracking frame information and the photometric outputs of the divided photometric areas belonging to this frame are stored in the memory, they are shifted in the vertical, horizontal, and diagonal left, right, up, and down directions with respect to the dotted frame.
The calculation shown in Expression (3) is performed on the street tracking frame and the previous tracking frame indicated by the dotted line. In FIG. 10B, since the subject T is moving diagonally upper right, the minimum value of D is obtained when the tracking frame is shifted diagonally upper right (the position is indicated by a thick line). Therefore, in this case, the tracking frame G is shown in FIG.
From (a) to the position shown in FIG. 10 (b), the tracking operation of the subject is performed.

Therefore, according to this embodiment as well, it is possible to obtain the same effects as those of the above-mentioned first embodiment. In particular, in this embodiment, the size of the tracking frame does not change even if the size of the subject changes during tracking, but if the size of the subject does not change, the number of divided metering areas used for subject tracking is always constant. Therefore, the tracking operation can be ensured, and the object can be tracked with high accuracy. In addition, it is not necessary to perform the grouping calculation in step S107 as in the first embodiment, and the tracking operation can be made faster by this amount.

In the correspondence between the embodiment described above and the scope of the claims, the photometry section 11 is the photometry means, the group creation section 12 is the grouping means, the tracking frame setting section 13 is the tracking frame setting means, and the subject tracking is performed. The unit 14 constitutes subject tracking means, and the display unit 17 constitutes tracking frame display means. In addition,
The subject tracking device of the present invention is not limited in details to the above-described embodiments, but can be variously modified. As an example,
Each of the above-described embodiments is an example applied to a still camera using a so-called silver salt film, but is also applicable to a still camera using a recording medium such as a memory and a floppy, and further to a video camera.

[0031]

As described in detail above, according to the present invention, the inside of the field is classified into a plurality of groups based on the photometric information of the plurality of photometric areas of the field, and the plurality of groups are classified. Set the contour of the group existing near the optical axis of the shooting lens as the initial value of the tracking frame for tracking the subject, and set the photometric information of the photometric areas that belong to the tracking frame and the photometric information of the photometric areas that belong to each group. The tracking frame is moved based on the difference between the two, and the number of overlapping photometry areas between the photometry areas belonging to the tracking frame and the photometry areas belonging to each group, so that the main subject is tracked within the scene. Therefore, unlike the conventional case, it is not necessary for the photographer to manually set the tracking frame, and proper initial setting of the tracking frame can be performed without bothering the photographer.

[Brief description of drawings]

FIG. 1 is a diagram showing a camera to which a subject tracking device according to a first embodiment of the present invention is applied, and is a block diagram showing a main part thereof.

FIG. 2 is a diagram showing an optical system of the camera of the first embodiment.

FIG. 3 is a diagram showing a photometric element of the first embodiment.

FIG. 4 is a diagram showing a dividing element according to a first embodiment.

FIG. 5 is a diagram showing a segment of the on-screen liquid crystal according to the first embodiment.

FIG. 6 is a diagram showing a state in which a tracking frame is displayed by an on-screen liquid crystal.

FIG. 7 is a flowchart for explaining the operation of the first embodiment.

FIG. 8 is a diagram illustrating a procedure for setting a tracking frame and tracking an object according to the first embodiment.

FIG. 9 is a diagram illustrating a procedure of a camera to which the subject tracking device according to the second embodiment of the present invention is applied.

FIG. 10 is a diagram illustrating a procedure for setting a tracking frame and tracking an object according to the second embodiment.

FIG. 11 is a diagram showing a result of grouping calculation by a group creating unit.

[Explanation of symbols]

9 Photometric element 10 on-screen liquid crystal 11 Light meter 12 Group creation department 13 Tracking frame setting section 14 Subject tracking unit 15 Exposure calculator 16 Exposure control section 17 Display

Front page continuation (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01S 3/76-3/789 G03B 17/18-17/20 G03B 17/36 G01J 1/00-1/60 G01J 11 / 00

Claims (3)

(57) [Claims] 1. A photometric unit that divides a field into a plurality of matrix-shaped photometric regions to perform photometry, and outputs a plurality of photometric information regarding the brightness of the field, and the field based on the photometric information. Multiple groups within the circle
Grouping means to classify into, and among the plurality of groups, present near the optical axis of the photographing lens
The initial value of the tracking frame for subject tracking the outline of the group of the
Wherein the tracking frame setting means for setting, and the photometric information of the photometric areas belonging to the tracking frame in each
The difference from the photometric information of the photometric area belonging to the group, and
And the photometric area and each group belonging to the tracking frame
Of the photometric area overlapping with the photometric area belonging to
An object tracking device, comprising: an object tracking unit that moves the tracking frame based on a number to track the main object in the object scene. 2. The subject tracking device according to claim 1, further comprising a tracking frame display unit that displays the tracking frame set by the tracking frame setting unit in the object scene. Tracking device. 3. The subject tracking device according to claim 1, wherein the photometric unit outputs information regarding a color of a subject existing in the object scene as photometric information, and the subject detecting unit has a similar color. The photometric area having a component is divided to detect the main subject and its size, and the tracking frame setting means sets the contour of the photometric area belonging to the division in which the main subject exists as the tracking frame. A subject tracking device characterized in that