JPH09127405A - Optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the precision of automatic selection of an area where a principal object exsist in an observation picture. SOLUTION: Area division means 102 and 103 which divide the observation face into areas based on plural distance measurement or defocus extent detection results and an area extraction means 104 which extracts at least one area, where the principal object exists, from plural areas divided by area division means and operates the degree of inclination of the object to the optical axis of an objective lens based on plural distance measurement results and takes it as a discrimination element of the principal object are provided, and the degree of inclination of the object is operated, and this inclination information and absolute distance information or the defocus extent are synthetically evaluated, thereby determining the principal object.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an area dividing means for dividing an observation surface into areas based on a plurality of distance measurement results or defocus results, and a main object from a plurality of areas divided by the area dividing means. The present invention relates to a distance measuring device, a focus detecting device, and an optical device such as a camera equipped with these devices, the distance measuring device and the focus detecting device including at least one region in which an area in which an object exists is extracted.

[0002]

2. Description of the Prior Art In a conventional camera capable of multi-point distance measurement, if the distance measurement is performed by always selecting the closest distance measurement area from a plurality of distance measurement results, incorrect distance measurement may occur. Since there are many, for example, when the result of three-point distance measurement has a specific pattern such as distance, middle, and near, the distance measuring point of “medium” is selected (“near” may mean the ground, etc.). Proposal of a method having an algorithm such as (for example, JP-A-2-2822).
34).

Further, a large number of distance measuring points are provided in the photographing screen,
An apparatus has been proposed by the applicant of the present application (Japanese Patent Publication No. 4-67607) that can measure a distance (defocus amount) in an arbitrary direction in a photographing space by performing distance measurement at these distance measuring points.

The proposed apparatus will be described by taking as an example the case of shooting a scene as shown in FIG.

First, the photographed screen is finely divided into blocks (a plurality of pixels on the area sensor is set) to measure the distance,
Next, distance distribution information (distance map) as shown in FIG. 7 is obtained. Then, in order to determine the object arrangement in the object space, the objects forming the space are grouped.

FIG. 8 shows an example of the result of grouping based on the distance map data of FIG. 7, and the regions are divided for each object by the grouping.

As a practical grouping method, some methods are generally known. The simplest example is that if the difference in distance (or defocus) between two adjacent blocks is less than or equal to a predetermined value, it is determined that the two blocks form the same object for all adjacent blocks. It is a method of applying.

By the method as described above, the screen is divided into regions (grouping) for each object constituting the photographing space as shown in FIG.

Then, for example, the area of the main subject is determined from the objects forming the photographing space by using the distance information, the size information of the object, the position information on the screen, and the like.

[0010]

However, in any of the above proposed devices, in the case of the scene as shown in FIG. 9, that is, the scene in which the table 2 is in front of the person 1 who is the main subject, Because the distance to person 1 is short,
There was a risk of selecting the table 2 or the area where the tableware was measured. Therefore, in such a case, the photographer must perform the work of manually selecting the distance measuring area after switching the distance measuring area selection mode to manual in order to select the desired distance measuring area. The operation was troublesome.

(Object of the Invention) It is an object of the present invention to provide an optical device capable of improving the accuracy of automatic selection of a region where a main object exists in an observation screen.

[0012]

[Means for Solving the Problems] Taking a camera as an example, in a general shooting scene, an object that is considered as a main subject such as a person and an object such as a table or the ground that is not the main subject even at a short distance are considered. The difference is often in the inclination of the surfaces that make up the object.

That is, since the main subject often faces the camera, an object formed of a plane perpendicular to the photographing optical axis is often the main subject. On the other hand, an object that is not the main subject such as the ground or a wall even at a short distance is often composed of a surface having an inclination with respect to the photographing optical axis.

In view of these points, the present invention according to claims 1 to 4 is based on distance measuring means for measuring a distance between a plurality of points on an observation plane and a plurality of distance measuring results by the distance measuring means. A region dividing means for dividing the observation surface into regions, and at least one region in which the main object exists is extracted from the plurality of regions divided by the region dividing means, based on a plurality of distance measurement results. The present invention according to claims 5 to 7 further comprises a region extracting means for calculating the degree of inclination of the object with respect to the optical axis of the objective lens and using this as a determination element for the main object. Defocus amount detecting means for detecting the defocus amount of the, the area dividing means for dividing the observation surface into regions based on the plurality of defocus results by the defocus amount detecting means, and the plurality of divided areas by the area dividing means. The main object from the area At least one existing region is extracted, and the degree of inclination of the object with respect to the optical axis of the objective lens is calculated based on a plurality of defocus results, and the region extraction means uses this as a determination element of the main object. By including the degree of inclination of the object, and comprehensively evaluating this inclination information, absolute distance information and defocus amount,
I try to determine the main object.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on illustrated embodiments.

FIG. 1 is a block diagram showing a schematic configuration of a camera according to the first embodiment of the present invention.

In FIG. 1, 200 is a lens, 201 is an area sensor such as a CCD in which minute light receiving pixels are two-dimensionally arranged, and 202 is a sensor drive circuit for driving the area sensor 101. A microcomputer 203 is an A / D converter for converting the output from the area sensor into a digital signal and an A / D converter for the A / D converter.
Frame memory (FM) for storing converted image signals
CPU that performs distance map creation and grouping described later
Is provided.

Reference numeral 204 is a shutter control circuit for controlling the opening and closing of the shutter, 205 is a film control circuit for controlling the feeding of the film, and 206 is the microcomputer 203.
A lens drive circuit for driving the taking lens based on the distance measurement information selected by 207, a switch (SW1) 207 that is turned on by the first stroke of a release button (not shown),
208 is O by the second stroke of the release button (not shown)
This is a switch (SW2) for N.

Next, a series of operations executed by the microcomputer 203 will be described with reference to the flowchart of FIG.

In step (101), the first stroke of the release button (not shown) is made and the switch SW1
It is determined whether or not is turned on. If it is turned off, this step remains until it is turned on.

After that, when the switch SW1 is turned on, the process proceeds to step (102) to drive the area sensor 201 via the sensor drive circuit 202. Then, the shooting screen is divided into blocks, and a known calculation is performed in each block to calculate the distance to the object in the block. As a result, a distance map that represents the distribution of distances over the entire shooting screen is created.

For example, in the case of a shooting scene as shown in FIG.
A distance map as shown in FIG. 7 will be created.

Next, in step (103), grouping is performed based on the distance map data.

As described above, the grouping method is the distance (or defocus) between two adjacent blocks.
If the difference between is less than or equal to a predetermined value, it is already known to apply the determination that two blocks form the same object to all adjacent blocks.
Further description is omitted.

By making such a judgment, FIG.
As shown in, it is possible to obtain data in which the photographing screen is divided into regions for each object.

Next, in step (104), the main subject is determined from all the objects (groups) constituting the screen.

As elements for judging the main subject,
In the prior art, the focus is on the concept of closest proximity, and in the case of the shooting scene of FIG. 6, the region 3 shown in FIG. 8 is closest, so the focus is on the wall. As another evaluation element, a method of introducing the size of the object, the position on the screen, or the like as a determination element is conceivable. For example, in the shooting scene as shown in FIG. In spite of this, the area 5 has better conditions in terms of distance, size, and position, and the object in the area 5 is determined to be the main subject.

On the other hand, in the present embodiment, in addition to these evaluation factors, the degree of inclination of the object with respect to the photographing optical axis is calculated and evaluated to accurately determine the main subject. is there.

Therefore, in step (104), the inclination of each group is first calculated.

An example of implementation of inclination calculation will be described.

As shown in FIG. 4, a point 6 on the surface of the object is seen from the camera.
When the differential path s is considered for the vector r up to
The inclination k of the object surface with respect to the plane perpendicular to the optical axis can be expressed by k = | (dr / ds) · n |. Here, n is a unit vector in the optical axis direction. Consider a case where this formula is applied to a region (object) grouped as shown in FIG.

Here, for simplicity, the block aspect ratio is set to 1: 1, the lens focal length is f, the side length of the block on the image plane is L, and the average distance to the group is d _a. In such a case, the length of the side of the block on the object plane can be represented by m = Ld _a / f on average. Here, if the distance of the i-th block B _i in the group is d _i , for example, the block B ₆
Of the gradient kθ (6) of k ₀ (6) = | d ₇ −d ₅ | / 2m k ₄₅ (6) = | d ₁₀ −d ₂ for each differential angle shown in FIG. 5B. | / 2√ (2) m k ₉₀ (6) = | d ₉ −d ₃ | / 2m k ₁₃₅ (6) = | d ₈ −d ₄ | / 2√ (2) m.

Further, in the case of a block forming an edge of a group such as the block B ₁ , the edge is taken into consideration, k ₀ (1) = 0 k ₄₅ (1) = │d ₄ -d ₁ | / √ (2) m k ₉₀ (1) = | d ₃ −d ₁ | / m k ₁₃₅ (1) = | d ₂ −d ₁ | / √ (2) m block data in the group Calculate using only. Similarly, the slope is calculated for all blocks.

Next, as an index representing the inclination of the entire group Is calculated, and the maximum value among them is set as an index kmax _indicating the slope of the group.

Here, the angle with respect to the plane perpendicular to the optical axis can be expressed by θ _max ≈tan ⁻¹ (k _max / m), which is taken as the tilt angle of the group.

The above-described inclination calculation is performed for all the groups and used as the evaluation element of the main subject.

For example, a condition that "a group tilted by a predetermined value (for example, 30 degrees or more) with respect to a plane perpendicular to the optical axis is not recognized as a main subject" is added to the known distance measuring area selection algorithm. As a result, even in the shooting scenes shown in FIGS. 6 and 3, the wall, the table surface, etc. can be excluded from the main subject candidates, and the main subject can be correctly recognized.

Although the predetermined value is set with respect to the angle here, even if the predetermined value is set with respect to the index k _{max indicating} the inclination, the inclination angle is almost the same although there is some variation depending on the distance. Can be calculated.

Returning to FIG. 2 again.

Next, in step (105), a distance measurement area using lens drive is determined from the area of the group determined to be the main subject in step (104) to obtain distance measurement information.

Known algorithms such as closest priority, contrast priority, or depth priority can be considered as the determination algorithm of the distance measurement area. For example, when it is determined that the shape of the group is close to human, There is an algorithm such as focusing on a certain upper part.

In the next step (106), the lens is driven through the lens drive circuit 206 of FIG. 1 based on the distance measurement data determined in the above step (105). In the following step (107), it is determined whether or not the ON state of the switch SW1 is continued, and if it is continuing, the process proceeds to step (108), while if it is OFF, the step (10) is performed.
Return to the initial state of 1).

In the next step (108), the switch S
It is determined whether or not W2 is ON. If it is OFF, the process returns to step (107), and the switch SW is set as described above.
The state of 1 is determined. If it is turned on, the process proceeds to step (109) to drive the shutter control circuit 204 and an aperture control circuit (not shown) to execute a known exposure operation, and then drive the film control circuit 105 to move the photographing frame. One frame is wound and a series of operations is completed.

In the first embodiment described above, the description has been made assuming the camera provided with the distance measuring means for calculating the absolute distance, but of course the camera provided with the focus detection device for calculating the defocus amount. However, it can be similarly applied.

(Second Embodiment) Next, a second embodiment according to the present invention will be described. Note that the circuit configuration of the camera and the flow of the entire processing of photographing are the same as those in the flowchart of FIG. 1 used in the first embodiment, and therefore these are not shown here.

FIG. 2 is different from the first embodiment described above.
An example of a determination algorithm of the degree of inclination in the main subject determination in step (104) of (3), in which the degree of inclination is simply calculated for each group grouped in step (103) will be described.

For example, as shown in FIG. 5, the maximum and minimum distances d _max and d _min are obtained from the distance data measured in all the blocks B _{1 to} B ₆ included in one group, and these are calculated. Distance difference d _diff = d _max −d _min (1) is calculated.

This distance difference represents the depth of the surface of the object, and is a simple index indicating whether the subject is tilted with respect to the photographing optical axis.

The above calculation of the distance difference is carried out for all the blocks and used as the evaluation element of the main subject.

If this distance difference exceeds a predetermined value,
The object can be excluded from the main subject candidates as having an inclination to some extent.

For example, when the predetermined value is set to 1 m, in the scenes of FIG. 6 and FIG. 3, the wall and the table are excluded from the main subject candidates because the distance difference is 1 m or more, but the erect human being is excluded. Is unlikely to have a distance difference of 1 m or more, the main subject candidate is set to a person.

Even in the case of a camera capable of detecting the defocus up to the subject, a calculation close to this can be performed. The maximum and minimum defocus d _fmax and d _fmin are obtained from all the defocus results in one group,
These defocus difference d _fdiff = d _fmax -d _fmin ............ (2) to calculate. Here, the defocus value can be expressed as follows: d _f = a / d + b (3) where d _f is the distance to the object. Here, a and b are constants determined by the ranging optical type. Therefore, equation (2) _{d fdiff = d fmax -d fmin =} {(a / d min) + b} - {(a / d max) + b} = a · {(d max -d min) / (d _min · d _max )} ………… (4) Compared to the above formula (1), the defocus difference varies depending on the absolute distance even if the distance is the same, but the inclination is particularly large for a short-distance subject. It is possible to determine the presence or absence, and it is possible to determine the main subject in consideration of the inclination even from the defocus value.

As described above, in the second embodiment, by introducing a simple inclination judgment algorithm, even in a camera or the like in which the operation speed of the microcomputer is slow,
There is an advantage that the main subject determination can be performed at high speed.

According to each of the above-mentioned embodiments, after the distance of the photographing space is finely divided into blocks and the distances are grouped, the degree of inclination of each object is calculated, and the inclination information is added to the main subject judgment element. By determining the main subject based on this, it becomes possible to effectively limit the candidate areas of the focus detection points, and it is possible to greatly reduce the erroneous determination of the focus detection points as in the conventional case. Therefore, in any shooting scene, it is possible to always automatically take a picture of the intended main subject.

(Correspondence between Invention and Embodiment) In this embodiment, the portion of the microcomputer 203 which executes the operations of steps (102) and (103) corresponds to the area dividing means of the present invention. And step (10
The part that executes the operation of 4) corresponds to the area extracting means of the present invention.

The above is the correspondence relationship between each configuration of the embodiments and each configuration of the present invention, but the present invention is not limited to the configurations of these embodiments, and the functions shown in the claims,
Needless to say, any configuration may be used as long as the functions of the embodiment can be achieved.

(Modification) The present invention is applied to a camera such as a single-lens reflex camera by way of example, but may be a distance measuring device, a focus detecting device or a focus adjusting device mounted on the camera. Further, it is also applicable to environment recognition devices such as air conditioners (for example, used as a device for recognizing a person and setting the wind direction in that direction) and cars (used as a person recognition device).

In addition, the present invention can be applied to an optical device including a distance measuring device and a focus detecting device to which the present invention is applied, such as binoculars and a game machine.

[0059]

As described above, according to the present invention,
Based on a plurality of detection results by the distance measuring means or the defocus amount detecting means, at least an area dividing means for dividing the observation surface into an area and an area in which the main object exists among the plurality of areas divided by the area dividing means One is extracted, and the degree of inclination of the object with respect to the optical axis of the objective lens is calculated based on a plurality of distance measurement results, and the area extraction means having this as a determination element of the main object is provided. The main object is determined by calculating the degree of ∘ and comprehensively evaluating the tilt information, the absolute distance information, and the defocus amount.

Therefore, it is possible to improve the accuracy of automatic selection of the area where the main object exists in the observation screen.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a camera according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing a series of operations of the camera of FIG.

FIG. 3 is a diagram showing an example of a shooting scene in the first embodiment.

FIG. 4 is a diagram for explaining a tilt calculation in the first embodiment.

FIG. 5 is a diagram for explaining group tilt calculation in the first embodiment of the present invention.

FIG. 6 is a diagram showing an example of a shooting scene for explaining a difference in effect between the conventional example and the first embodiment.

7 is a diagram showing an example of the distance map of FIG.

FIG. 8 is a diagram showing an example when the groups shown in FIG. 7 are grouped.

FIG. 9 is a diagram showing an example of a shooting scene that a conventional apparatus is not good at.

[Explanation of symbols]

 201 area sensor 202 sensor drive circuit 203 microcomputer 206 lens drive circuit

Claims (7)

[Claims] 1. A distance measuring means for measuring a plurality of points on an observation plane, an area dividing means for dividing an observation surface into areas based on a plurality of distance measurement results by the distance measuring means, and an area dividing means. An optical device comprising: an area extracting means for extracting at least one area in which a main object exists from a plurality of divided areas, wherein the area extracting means is an objective lens optical axis based on a plurality of distance measurement results. An optical device, which is a means for calculating a degree of inclination of an object with respect to, and using this as a determination element of a main object. 2. The distance measuring information calculating means for calculating at least one distance measuring information based on the distance measuring result of the main object area extracted by the area extracting means. Optical device. 3. The area extracting means comprises means for calculating an angle of the object with respect to the optical axis of the objective lens from a plurality of pieces of distance information obtained by the distance measuring means, and using the calculated angle as an element for determining a main object. The optical device according to claim 1 or 2, which is characterized in that. 4. The area extracting means determines at least 2 of the surface of the object from a plurality of distance information obtained by the distance measuring means.
3. The optical device according to claim 1, wherein the optical device is means for calculating a distance difference between points and using the difference as a determination element for a main object. 5. A defocus amount detection means for detecting defocus amounts of a plurality of points on the observation surface, and area division for dividing the observation surface into areas based on a plurality of defocus results by the defocus amount detection means. Means and an area extraction means for extracting at least one area where a main object exists from the plurality of areas divided by the area division means, wherein the area extraction means is a plurality of defocus results Calculate the degree of inclination of the object with respect to the optical axis of the objective lens based on
An optical device characterized in that it is means for using this as a judgment element of a main object. 6. The defocus information calculating means for calculating at least one defocus information based on the defocus result of the main object area extracted by the area extracting means. Optical device. 7. The area extracting means calculates a defocus difference between at least two points on an object surface from a plurality of defocus information obtained by the defocus detecting means,
7. The optical device according to claim 5, wherein the optical device is a device that uses this as a determination element for a main object.