JPH07110429A - Camera provided with object tracking function - Google Patents

Abstract

PURPOSE:To automatically and surely obtain required object information by automatizing the setting a tracking frame when an object is tracked and enhancing the tracking accuracy of the object. CONSTITUTION:This camera is provided with a photometry means 10 dividing a field to plural areas, executing the photometry of the respective areas and respectively outputting the photometry data of the object parts existing in the respective areas; an object set means 11 setting the object part in the field which should be tracked; a tracking frame set means 13 setting the area provided with the photometry data similar to the object part set by the set means 11 as the tracking frame; and an object tracking means 15 successively extracting the area provided with the photometry data similar to the photometry data in the tracking frame set by the set means 13. When the desired initial tracking area is set by the set means 11, the proper tracking frame is automatically set and the object is automatically tracked by the set means 13 and the tracking means 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera having a subject tracking function, and more particularly, to a camera capable of automatically setting the size of a tracking field of view when tracking a subject according to the size of the tracked subject. The present invention relates to a technology that enables accurate subject tracking.

[0002]

2. Description of the Related Art Conventionally, in order to automatically adjust the exposure and focal length of a camera, as a technique of recognizing where the main subject is in the field and automatically tracking its position,
The one disclosed in JP-A-61-2177 is known. This technology relates to an automatic tracking device for a main subject particularly in an automatic focus detection or automatic focus adjustment device for a video camera, and in order to recognize the movement of the main subject to be tracked, the size of the tracked subject is tracked. By manually adjusting and setting the size of the field of view,
Put the tracked subject within the accurate effective range of the tracking field of view,
It is intended to realize accurate subject tracking.

[0003]

However, in such a conventional camera having a subject tracking function,
Since the tracking field of view is set manually, it is impossible to always set a stable tracking field of the correct size according to the size of the tracked subject. Could not be performed with high accuracy. Also, in order to manually set the tracking field of view according to the size of the main subject, it is necessary to operate the setting buttons while always being aware of the size of the subject. There was a risk of missing an opportunity.

If the tracking field of view is not accurately set according to the size of the tracked object, for example, if the size of the set tracking field of view is considerably larger than the size of the tracked object, the tracking field of view is set. The ratio of the portion other than the tracking subject such as the background to the tracking field of view increases, and the tracking field of view contains a lot of unnecessary object data such as the background, which causes the accuracy of the measured data to decrease. .

Therefore, it is an object of the present invention to allow a camera having a subject tracking function to automatically set an appropriate size of a tracking field of view for recognizing a tracked subject to track the subject. To do so.

Another object of the present invention is to make it possible to easily set a tracking frame in a camera having a subject tracking function, and to reliably capture a tracked subject for highly accurate subject tracking. Especially.

[0007]

In order to solve the above problems, according to the present invention, in a camera having a subject tracking function, the field of view is divided into a plurality of regions for photometry, and the subjects existing in the respective regions are measured. A photometric device that outputs the photometric data of each portion, a subject setting device that sets a subject portion to be tracked in the object scene, and an area having photometric data similar to the subject portion set by the subject setting device. A tracking frame setting means for setting as a tracking frame, and a subject tracking means for sequentially extracting a region having photometric data similar to the photometric data in the tracking frame set by the tracking frame setting means are provided. .

Further, it is convenient to set the area of the region of the subject portion set by the subject setting means to be equal to or smaller than the area of the region of the tracking frame set by the tracking frame setting means.

Further, the range of the subject portion set by the subject setting means may be the size of one area of the photometric means.

The tracking frame setting means can also set the size of the tracking frame based on the output of the photometric means.

Further, the tracking frame setting means may set, as the tracking frame, an area similar in brightness and / or hue to the subject portion to be tracked set by the subject setting means.

Further, the subject tracking means can also sequentially extract regions similar to the brightness and / or hue of the subject portion in the tracking frame.

[0013]

With this structure, the subject setting unit sets the subject portion to be tracked by the subject setting unit based on the photometric data obtained by dividing the field into a plurality of regions by the photometric unit and performing photometry. A region having photometric data similar to the subject portion is set as a tracking frame by the tracking frame setting means. Then, the subject tracking means sequentially extracts regions having photometric data similar to the photometric data in the tracking frame to perform subject tracking, so that the size of the tracking frame is automatically adjusted according to the size of the tracked subject. Is set. Therefore, since the tracking frame is always set to an appropriate size, the tracked subject can be reliably caught and tracked by the tracking frame, and the information necessary for shooting can be obtained automatically and accurately. In addition, the ratio of the extra information other than the tracked subject included in the tracking frame is extremely small, and the necessary information about the subject can be accurately obtained.

Further, the area of the object portion set by the object setting means is set to be equal to or smaller than the area of the tracking frame set by the tracking frame setting means, for example, one area of the photometric means, so that tracking is performed. It is possible to select any desired characteristic portion in the subject portion to be set and set it as the tracked subject. Therefore, the tracking frame can be easily set, and the tracked subject can be reliably recognized, so that more accurate subject tracking can be performed.

Further, in the tracking frame setting means, the size of the tracking frame is set based on the output of the photometric means, so that the tracking frame can be set without providing a special photometric means for tracking an object. Subject tracking can be performed.

Further, in the tracking frame setting means, an area similar in brightness and / or hue to the object portion to be tracked set by the object setting means is set as a tracking frame, so that the object should be tracked in the field. When the area of the subject portion changes, the size of the tracked subject can be accurately recognized and the size of the tracking frame can be changed, so that the information included in the subject to be tracked can be accurately extracted. it can.

Further, in the subject tracking means, the movement and size change of the tracked subject can be surely recognized by sequentially extracting the regions similar to the brightness and / or the hue of the subject part in the tracking frame. This makes it possible to reliably track the tracked subject.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of a camera having a subject tracking function according to an embodiment of the present invention. The subject tracking function of this camera is used, for example, to obtain subject information for performing automatic exposure control, and the photometric unit 10 that divides the field into a plurality of areas for photometry, and the photographer performs tracking. A subject setting unit 11 that sets a part of the subject to be used as an initial tracking region, a group creation unit 12 that groups regions of similar hues in the scene, and a tracking frame setting that expands the initial tracking region and sets a tracking frame. Unit 13, an information storage unit 14 that stores position information of the tracking frame and subject information in the tracking frame, a subject determination unit 15 that determines a subject to be tracked from a plurality of subjects in the scene, and from the obtained subject information An exposure calculation unit 16 that calculates an appropriate exposure value, and an exposure control unit 17 that controls the aperture value of the camera based on the appropriate exposure value.
It consists of Further, the functions of the group creation unit 12, the tracking frame setting unit 13, the information storage unit 14, the subject determination unit 15, the exposure calculation unit 16, and the like can be realized by the microprocessor installed in the camera.

As shown in FIG. 2, the photometric section 10 is constructed by arranging light receiving elements corresponding to each photometric area in an array. In this embodiment, a total of 240 photometric areas are formed in an array of 12 rows and 20 columns on the surface of the light receiving element irradiated with light, and the field is decomposed into 240 photometric areas. It is designed to measure light. These 24
As shown in FIG. 3, each of the 0 photometric areas is composed of three elements for detecting R (red), G (green), and B (blue) in one photometric area. That is, the light receiving element is composed of a total of 720 photometric elements. In the following description, the lower left corner is (1,1) and the upper right corner is (20,12) as the address indicating the position of the photometric area.

Next, the outline of the function of each block in FIG. 1 and its relation will be described. The photometric unit 10 divides the subject image into a plurality of photometric regions for photometry, and outputs the photometric data to the group creation unit 12. The group creating unit 12 groups the subjects in the field based on the photometric data from the photometric unit 10.

In parallel with this, in the subject setting section 11, information of a part of the tracked subject area selected by the photographer is stored as position information of the tracked subject, and the tracking frame setting section 13 stores the information. Output. The tracking frame setting unit 13 sets the tracking frame of the subject to be tracked based on the position information of the tracked subject of the subject setting unit 11 and the group information of the group creation unit 12. The information storage unit 14 stores information about the set tracking frame based on the information of the tracking frame setting unit 13 and the photometric unit 10.

The subject determining unit 15 is a group creating unit 12
A new tracking frame is determined based on the group information from the tracking information and the tracking frame information from the information storage unit 14. In addition, the information storage unit 1
The tracking frame information stored in 4 is updated every time the tracking frame is changed by the subject determining unit 15.

Then, the exposure calculation section 16 calculates an appropriate exposure value based on the information in the photometry section 10 and the information storage section 14. Based on the proper exposure value information of the exposure calculation section 16, the exposure control section 17 controls an aperture and a shutter (not shown) to expose the film.

FIG. 4 schematically shows the optical system of the camera of this embodiment. The optical system shown in FIG. 4 includes a photographic lens 1 for focusing a subject image on a photographic film surface (not shown), a quick return mirror 2 for directing a light flux from the subject to the photographer side when the photographic film is not exposed, The diffusion screen 3, the condenser lens 4, the well-known pentaprism 5, the eyepiece lens 6, the photometric prism 7 for directing a light beam to the light receiving element 9, and the light receiving element 9 are used to re-form the subject image so that the subject image can be seen by the photographer. It is composed of a photometric lens 8 for forming an image and a photometric element 9 for measuring the light intensity of a subject.

In the optical system of FIG. 4, the incident light flux from the subject is of two systems: a light flux reaching the photographer's eyes and a light flux reaching the light receiving element 9 for measuring the light intensity of the field. It is divided into The light flux that reaches the photographer's eye enters the photographing lens 1, passes through the quick return mirror 2, the diffusion screen 3, the condenser lens 4, the pentaprism 5, and the eyepiece 6 and reaches the photographer's eye. On the other hand, in the light flux used to measure the light intensity of the subject, a part of the light flux diffused by the diffusion screen 3 is
The light reaches the light receiving element 9 through the condenser lens 4, the penta prism 5, the photometric prism 7, and the photometric lens 8.

Next, with reference to FIGS. 5 and 6, the subject tracking process of the camera of this embodiment will be described in detail. Figure 5
4 is a flow chart showing an algorithm when an exposure calculation based on subject information obtained by the tracking function of the camera of the present embodiment is performed by a microcomputer incorporated in the camera. Further, FIG. 6 shows a part of the process for realizing subject tracking as an image in the scene, and FIG. 6A shows the most characteristic part of the main subject to be tracked as the initial tracking region G1. Setting step, (b) is G
The step of enlarging and setting the tracking frame to G2 on the basis of the information of the portion designated in 1, (c) shows the position and size of the tracking frame for the subject whose position and size have changed after a certain period of time. The stage in which tracking is performed by changing it is shown.

The process of FIG. 5 is started by, for example, half-pressing the release button of the camera. First, in step 101, the parameter i is initialized to 1. The value of i = 1 indicates that this program is the first execution after starting. Next, in step 102, the subject setting unit 11 initializes the tracking subject. In this case, as shown in FIG. 6 (a), one predetermined area in the approximate center of the screen is set as the initial tracking area G1, and its position information is stored in the information storage unit 14 provided in the microcomputer. . Here, the initial tracking area G1 is the address (10, 6) of the photometric area of the light receiving element 9 shown in FIG. Therefore, the photographer can set the tracking subject by first pressing the release button halfway after framing the most characteristic part of the subject to be tracked to the tracking frame set to (10, 6).

Next, in step 103, the photometric unit 10
The photometry of the object scene is carried out, and the information of the object scene is stored in the memory as R, G, and B photometric values for each of the 240 areas.

Next, in step 104, the group forming unit 12 groups the subjects in the entire field. Grouping is performed in the photometric area of 240 areas,
The adjacent groups of similar hues are grouped into the same group. The grouping method is described in detail in Japanese Patent Laid-Open No. 4-310930 published by the present applicant, and therefore its explanation is omitted here. Objects are grouped in units of photometric areas, so the area of one group is 1
It is never smaller than the photometric area. Therefore, the area of one group is at least the area of the tracking frame set in step 102 or more.

Next, at step 105, it is judged if i = 1. Here, when i = 1, it means that step 105 has passed the first time since the program was started.

If i = 1, the process proceeds to step 106,
Substituting i = 0 in step 106 and then step 10
At 7, the tracking frame setting unit 13 sets the tracking frame. The tracking frame set here is a group including the initial tracking area G1 stored in the information storage unit 14 in step 102. This will be described with reference to FIG. 6. The initial tracking area G1 of FIG. 6A is set in the initial setting stage, and the group G2 shown in FIG. 6B is based on the initial tracking area G1.
When the areas of 2 are grouped, G2 includes G1, so that the new tracking frame is the entire group G2.

Subsequently, at step 109, new tracking frame information is stored. The tracking frame information is the positions of all the photometric areas in the tracking frame and the photometric values in the areas, and these pieces of information are stored in the information storage unit 14.

If it is determined in step 105 that i = 1 is not satisfied, the process proceeds to step 108 and the object determining section 15
To determine the tracking group. Go to step 108 after step 1
It is the case of passing through 05 for the second time or more. In this case, since step 109 has been passed at least once, the positions of all the photometric areas in the tracking frame and their photometric values are stored in the information storage section as tracking frame information. The tracking group is determined as follows.

First, the average value BVr, B of the R, G, B photometry values in the tracking frame is calculated from all the stored photometry values of the tracking frame.
Vg and BVb are calculated. Also, the immediately preceding step 104
In the above, if n groups are created, BVr [n], BVg [n], BVb [n] are similarly calculated for all n groups from all photometric values in the group.
And using those values, ΔBV shown in the following Equation 1
Calculate c [n].

## EQU1 ## ΔBVc [n] = Abs (BVr−BVr
[N]) + Abs (BVg-BVg [n]) + Abs (BVg-BVb [n])

Here, the symbol Abs is a function representing the absolute value of the number in parentheses. Then, G [n] shown in Equation 2 below is calculated using ΔBVc [n].

## EQU00002 ## G [n] = RN [n] -k.multidot. (. DELTA.BVc [n])

Here, RN [n] represents the number of photometric areas in the overlapping portion between the stored photometric areas in the tracking frame and the stored photometric areas in the group to be compared with the tracking frame. Further, k is such that ΔBVc [n] is G with respect to RN [n].
It is a positive constant for adjusting the degree of contribution to [n], and is set to an optimum value in advance. Then, G [n] is calculated in all of the newly created n groups, and the group giving the maximum value among them is set as a new tracking frame.

This will be described with reference to FIG. FIG. 6 (c)
In FIG. 3, the group G2 indicated by the dotted line is the information storage unit 1
4 is a tracking frame stored in FIG. Then, it is assumed that groups G3 and G4 are created by new grouping. For these groups G3 and G4, G [n] is calculated by Equation 1 and Equation 2, and G [n] having a large value is calculated.
The group that gives is the new tracking frame. In this case, G
3 has a large RN [n] because the photometric region of the entire group overlaps with the tracking frame G2, and G4 has a small RN [n] because the region hardly overlaps with G2. If ΔBVc [n] of G3 and G4 are equal, the new tracking frame becomes G3, and the position information and the photometric value of all the photometric regions included in G3 are stored in the information storage unit 14 as new tracking frame information. In this way, the tracking of the subject is realized by sequentially rewriting the tracking frame information following the movement of the subject.

In FIG. 6C, G3 and G4 are drawn as a frame as a grouped area, but only the G3 determined as the tracking frame is actually displayed in the viewfinder.

Thus, the latest tracking frame information is obtained in step 10.
In step 9, the information is stored in the information storage unit 14, and based on this information, the appropriate exposure is calculated by the well-known algorithm of the exposure calculation unit 16 in step 110. Then, in step 111,
It is determined whether or not a release button (not shown) is fully pressed, and if it is fully pressed, step 1
At 12, the exposure control means 17 controls the exposure based on the proper exposure value, and the program ends. If the release button is not fully pressed, step 10
Returning to step 3, the subject tracking is continued.

In the above embodiment, the photometric unit 10 is the photometric unit, the subject setting unit 11 is the subject setting unit, the tracking frame setting unit 13 is the tracking frame setting unit, the group creating unit 12, the subject determining unit 15, and the information. The storage unit 14 constitutes subject tracking means.

In this embodiment, the exposure control is performed based on the subject information obtained by subject tracking.
The purpose of using this subject information is not limited to exposure control, but can also be used for focus adjustment and the like.

[0042]

As described above, according to the present invention, after setting a part of the object to be tracked as the initial tracking frame, the initial tracking frame is adjusted by the tracking frame setting means to match the size of the object to be tracked. It is automatically enlarged to an appropriate size and set as a tracking frame. Therefore, since the subject to be tracked can always be reliably captured and tracked by the tracking frame, the accuracy of subject tracking can be greatly improved, and the subject information necessary for shooting can be automatically and accurately obtained. You can

Further, since the size of the tracking frame which is automatically set is adjusted to an appropriate size in accordance with the change in the size of the tracked object, the tracked object such as the background is placed in the tracked frame. The ratio of information other than the above is reduced, and the information of the main subject can be obtained with extremely high accuracy.

Further, since the area of the area of the object portion set by the object setting means is smaller than the area set as the tracking frame, a desired characteristic portion of the object to be tracked is selected and accurately specified as the object to be tracked. be able to.
Also, since the tracked subject can be accurately specified by specifying a partial area of the tracked subject, it is extremely easy to set the tracking frame, and the tracked subject can be reliably captured and tracked. You can

Furthermore, since the subject tracking is performed by setting a region having similar hue and brightness as the subject tracking frame and sequentially extracting the regions, it is possible to accurately change the position and size of the subject to be tracked. It can be captured and tracked, and necessary information of the main subject can be accurately extracted.

As described above, according to the camera having the subject tracking function of the present invention, highly accurate subject information can be obtained without increasing the operation burden on the photographer at the time of photographing, and an extremely high quality photograph can be taken. It becomes possible to do.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a camera having a subject tracking function according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an arrangement example of a photometric element that constitutes a photometric unit in the camera of FIG.

FIG. 3 is an explanatory diagram showing a detailed configuration of one area of the photometric element shown in FIG.

FIG. 4 is an explanatory diagram showing an optical system of a camera having a subject tracking function according to an embodiment of the present invention.

FIG. 5 is a flowchart showing a subject tracking procedure for exposure control in a camera having a subject tracking function according to an embodiment of the present invention.

FIG. 6 is an explanatory diagram showing, as an image in a field, a state of subject setting and tracking during a subject tracking operation in a camera having a subject tracking function according to an embodiment of the present invention.

[Explanation of symbols]

 1 Photographic Lens 2 Quick Return Mirror 3 Diffusing Screen 4 Condenser Lens 5 Penta Prism 6 Eyepiece 7 Photometric Prism 8 Photometric Lens 9 Photoreceptive Element 10 Photometric Section 11 Subject Setting Section 12 Group Creating Section 13 Tracking Frame Setting Section 14 Information Storage Section 15 subject determination unit 16 exposure calculation unit 17 exposure control unit G1 initial tracking area G2 tracking frame G3, G4 group area

Claims (6)

[Claims] 1. A photometric means for dividing a field into a plurality of areas for photometry and outputting photometric data of the field existing in each area, and an object portion to be tracked in the field is initially set. A subject setting unit that specifies using a setting frame, a tracking frame setting unit that sets a region having photometric data similar to the photometric data of the subject portion of the initial setting frame set by the subject setting unit as a tracking frame, A camera having a subject tracking function, comprising: a subject tracking unit that sequentially extracts regions having photometric data similar to the photometric data in the tracking frame set by the tracking frame setting unit. 2. The subject tracking function according to claim 1, wherein the area of the initial setting frame in the subject setting means is less than or equal to the area of the area of the tracking frame set by the tracking frame setting means. Camera with. 3. The camera with a subject tracking function according to claim 1, wherein the range of the initial setting frame in the subject setting means is the size of one area of the photometric means. 4. The camera having a subject tracking function according to claim 1, wherein the tracking frame setting means sets the size of the tracking frame based on the output of the photometric means. 5. The tracking frame setting means sets, as the tracking frame, an area similar in brightness and / or hue to a subject portion to be tracked set by the subject setting means. A camera having the subject tracking function described in 1. 6. The camera with a subject tracking function according to claim 1, wherein the subject tracking means sequentially extracts regions similar to the brightness and / or the hue of the subject portion in the tracking frame.