JP6924622B2 - Focus assist device and its program - Google Patents

Description

The present invention relates to a focus assist device and a program thereof.

Conventionally, in the shooting of commercial images such as movies and TV programs, the operation of focusing on the shooting target is basically performed by manual focus. In this manual focus, the cameraman directly rotates the focus ring of the lens or inputs the rotation angle of the focus ring as an analog value through an interface such as focus demand (analog knob). At this time, what the cameraman relies on is the image displayed in the finder, and the peaking process that emphasizes the edge portion of this image is performed to make adjustments so that the cameraman can easily check it.

In the field of movie shooting, a staff member who specializes in focusing visually measures the distance to the subject, and a cameraman and two people operate the camera. This staff requires experienced craftsmanship, and it is difficult to adopt this method at all shooting sites due to budget constraints.

Therefore, it is often the case that a 4K or 8K ultra-high-definition image is shot by a one-man operation in which the cameraman is also in charge of focusing. In this case, it has become very difficult to check whether or not the focus is accurate with a viewfinder of about 2 to 3 inches due to problems with the viewfinder and the resolution of the naked eye. Then, the out-of-focus that cannot be determined on the viewfinder greatly deteriorates the quality when viewing a high-definition image on a large screen.

Therefore, various methods have been proposed to assist the focus operation of the cameraman (for example, Patent Document 1). In the invention described in Patent Document 1, the cameraman can check even the details of the high-definition image by designating the enlarged area of the high-definition image with the pointing device and enlarging the area on the viewfinder.

Japanese Unexamined Patent Publication No. 2016-100883

However, the invention described in Patent Document 1 has a problem that the operation of the cameraman such as designation of an area by a pointing device becomes complicated and the cameraman takes time to master the operation.

Therefore, an object of the present invention is to provide a focus assist device and a program thereof that can realize accurate focus with a simple operation.

In view of the above problems, the focus assist device according to the present invention is a focus assist device for a camera having a viewfinder and operating the focus with the focus operation device, and is a focus range allocation means and a first subject. The configuration includes a selection means, a second subject selection means, a focus command means, and a viewfinder image generation means.

According to the focus assist device, distance information is input by the focus range assigning means, and the focus range of the camera that can be operated by the focus operation device is determined based on the distance for each subject determined by the input distance information. Assigned to each subject.
That is, the focus range assigning means acquires a set of distances to the subject (distance information), arranges the subjects in order of distance, and discretizes the focus range of the camera for each subject.

Further, in the focus assist device, the focus operation value is input from the focus operation device by the first subject selection means, and the input focus operation value is included in the focus range for each subject assigned by the focus range allocation means. The subject in the focused range is selected as the first subject.
In this way, the focus assist device only needs to select the subject (demand subject) that the cameraman wants to focus on through the familiar focus operation device.

As the focus operation device, for example, a conventional focus demand provided with an analog knob can be mentioned. Therefore, the operability of the focus operation device is the same as that of the conventional device, and the cameraman is accustomed to using it.

Further, in the focus assist device, the current focus value is input from the camera by the second subject selection means, and the input current focus value is included in the focus range for each subject assigned by the focus range assigning means. The subject in the focus range is selected as the second subject.

Further, the focus assist device is the first subject selected when the focus confirmation signal is input to the camera when the focus confirmation signal is input from the focus operation device by the focus command means. Command the focus on.
Further, the focus assist device reduces the image captured by the camera by the viewfinder image generation means, and generates a viewfinder image in which at least the first subject is highlighted.
Further, the focus range assigning means means that the attention subject and the rear subject located after the attention subject are arranged from an intermediate distance between the attention subject to which the focus range is assigned and the front subject located in front of the attention subject. The range up to the intermediate distance is assigned as the focus range of the subject of interest.
Further, in the first subject selection means, the focus operation value is input from the focus demand as the focus operation device.
Further, the focus command means commands the camera to focus when the focus confirmation signal is input from the focus demand.

According to the present invention, the following excellent effects are obtained.
The focus assist device according to the present invention can focus a camera on a subject that the cameraman wants to focus on by simply selecting a subject that the cameraman wants to focus on via a familiar focus operation device. As described above, the focus assist device according to the present invention can realize accurate focusing with a simple operation.

It is the schematic of the focus assist system which concerns on embodiment of this invention. It is explanatory drawing which explains the subject in this embodiment. FIG. 2 is an explanatory diagram illustrating the distance from the camera to the subject. It is a graph which shows the relationship between the focus operation value of focus demand, and the shooting distance of a camera in the prior art. It is a block diagram which shows the structure of the focus assist system of FIG. It is explanatory drawing explaining the extraction of the subject area in this embodiment. It is explanatory drawing explaining the generation of the distance information in this embodiment. It is explanatory drawing explaining the discretization of a focus range in this embodiment. In this embodiment, it is explanatory drawing explaining the demand subject and the in-focus subject. In this embodiment, it is explanatory drawing explaining the image for viewfinder which emphasized the demand subject and the in-focus subject. In this embodiment, it is explanatory drawing explaining the demand subject. In this embodiment, it is explanatory drawing explaining the image for a viewfinder in which a demand subject is highlighted. It is explanatory drawing explaining the DETAIL shift in this embodiment. In this embodiment, it is explanatory drawing explaining the image for a viewfinder in which a subject is enlarged and displayed. It is a flowchart which shows the operation of the range assist focus controller of FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. In the embodiment, the same means are designated by the same reference numerals, and the description thereof is omitted.

[Outline of Focus Assist System]
The outline of the focus assist system 100 will be described with reference to FIG.
The focus assist system 100 assists the cameraman's focus operation. This focus operation is to operate the position where the lens 15 is in focus, and in the present embodiment, the analog knob 2A of the focus demand 2 is rotated to input the distance.

As shown in FIG. 1, the focus assist system 100 includes a camera 1, a focus demand (focus operation device) 2, a distance measuring sensor 3, and a range assist focus controller (focus assist device) 4.

The camera 1 is a general photographing camera. In the present embodiment, the camera 1 is a camera that captures ultra-high-definition images such as 4K and 8K. In the present embodiment, the camera 1 captures an ultra-high-definition image, but it can also be applied to a camera that captures a low-resolution image of 2K or less.
The focus demand 2 is a general one in which a cameraman operates the focus of the camera 1. This focus demand 2 is sometimes called a focus knob. Although the camera 1 and the focus demand 2 are shown separately in FIG. 1, the focus demand 2 may be attached to the camera 1.

The distance measuring sensor 3 is a general sensor that measures the distance to the subject. In the present embodiment, the distance measuring sensor 3 is fixed to the upper surface of the lens hood of the camera 1 in the coaxial direction with the camera 1.
The Range Assisted Focus controller (RAF) 4 assists the cameraman's focus operation. Hereinafter, the range assist focus controller will be abbreviated as RAF. In this embodiment, the RAF 4 is connected to the camera 1 and the distance measuring sensor 3 via a cable. Further, the RAF 4 is connected to the focus demand 2 by using wireless communication such as Bluetooth (registered trademark).

For example, in the present embodiment, as shown in FIG. 2, seven subjects T (T _{1 to} T ₇ ) are photographed. In FIG. 2, the subject T ₁ is a dog, the subjects T ₂ , T ₃ , and T ₆ are women, the subjects T ₄ and T ₇ are men, and the subject T ₅ is a tree. As shown in FIG. 3, the subjects T _{1 to} T ₇ are arranged in the order of distance. That is, when viewed from the camera 1, the subject T ₁ is located at the foremost position, the subjects T _{2 to} T ₆ are arranged in this order, and the subject T ₇ is located at the rearmost position.

In the case of the conventional method, as shown in FIG. 4, the focus operation value (horizontal axis, Input) of the focus demand 2 and the shooting distance (vertical axis, Input) of the camera 1 have a linear relationship. Therefore, the cameraman needs to operate the focus demand 2 to accurately focus on the subject. However, it is difficult to perform an accurate focus operation just by visually observing the viewfinder whose resolution is significantly lower than that of the ultra-high-definition video. Therefore, the RAF 4 discretizes the focus range of the camera 1 that can be operated by the focus demand 2 for each subject (FIG. 8), and instructs the camera 1 to focus on the subject closest to the focus operation value of the focus demand 2. bottom.

The distance from the camera 1 to the subjects T _{1 to} T ₇ (subject distance) is d _{1 to d 7} . The vertical and horizontal axes of FIG. 4 show the shortest shooting distance (MOD), the longest shooting distance (FAR), and the subject distances d _{1 to d 7} . This shooting distance is the distance from each subject T to the image plane of the camera 1.

[Focus Assist System Configuration]
<Camera>
The configuration of the focus assist system 100 will be described with reference to FIG. 5 (see FIG. 1 as appropriate).
The camera 1 includes a camera body 11, a viewfinder 13, and a lens 15.
The camera body 11 includes an image sensor (not shown), records the captured ultra-high-definition video, and outputs the ultra-high-definition video (abbreviated as video in FIG. 5) to the viewfinder video generation means 46.
The viewfinder 13 displays a viewfinder image (abbreviated as VF image in FIG. 5) input from the viewfinder image generation means 46.
The lens 15 is a general zoom lens, and can drive the focus ring to control the shooting distance according to the shooting distance (focus command value) commanded by the focus command means 47. Further, the lens 15 outputs the current shooting distance (current focus value) to the focusing subject selection means 45 by an encoder (not shown). Further, the lens 15 outputs the focal length value (angle of view information) to the image generating means 46 for the viewfinder.

<Focus demand>
The focus demand 2 includes an analog knob 2A (FIG. 1), a SNAP switch 20A, a DETAIL switch 20B, a MAG switch 20C, a focus operation value output means 21, a SNAP switch determination means 23, and a DETAIL switch determination means 25. , MAG switch determination means 27.
In FIG. 5, the switch is abbreviated as SW.

Here, as shown in FIG. 1, the focus demand 2 can operate the focus of the camera 1 by rotating the analog knob 2A. Further, the focus demand 2 is provided with a SNAP switch 20A, a DETAIL switch 20B, and a MAG switch 20C on the outer peripheral portion so that the cameraman can press the switch.

The SNAP switch 20A is a switch that the cameraman presses when commanding the focus on the demand subject described later.
The DETAIL switch 20B is a switch that the cameraman presses when commanding the DETAIL shift described later.
The MAG switch 20C is a switch that the cameraman presses when instructing the enlarged display of the subject to be described later.

The focus operation value output means 21 outputs a focus value (focus operation value) corresponding to the rotation operation of the analog knob 2A to the demand subject selection means 44.
The SNAP switch determining means 23 determines whether or not the SNAP switch 20A is pressed, and when the SNAP switch 20A is pressed, outputs a SNAP switch pressing notification (focus confirmation signal) to the focus command means 47.
The DETAIL switch determining means 25 determines whether or not the DETAIL switch 20B is pressed, and when the DETAIL switch 20B is pressed, outputs a DETAIL switch pressing notification to the subject area extraction means 41 and the subject distance calculating means 42. be.
The MAG switch determining means 27 determines whether or not the MAG switch 20C is pressed, and when the MAG switch 20C is pressed, outputs a MAG switch pressing notification to the viewfinder image generating means 46.

<Distance measuring sensor>
The distance measuring sensor 3 measures the distance information of a subject distributed in the shooting direction of the camera 1, such as an infrared sensor that measures the distance by a TOF (Time Of Fly) method. Specifically, the distance measuring sensor 3 measures two-dimensionally with each pixel of the sensor measurement plane, using the time until the near-infrared LED is blinked at high speed and the near-infrared ray is reflected from the subject as the phase difference. do. Then, the distance measuring sensor 3 outputs the distance measuring data (lens vertical plane distribution distance measuring data) representing the distance for each pixel to the subject area extracting means 41 and the subject distance calculating means 42.

<RAF>
The RAF4 includes a subject area extraction means 41, a subject distance calculation means 42, a subject distance discretization means (focus range allocation means) 43, a demand subject selection means (first subject selection means) 44, and a focusing subject selection means. (Second subject selection means) 45, a viewfinder image generation means 46, and a focus command means 47 are provided.

The subject area extraction means 41 refers to the distance measurement data input from the distance measurement sensor 3 and extracts the subject area from the distance measurement data by a known subject area extraction method. In the present embodiment, the subject area extraction means 41 extracts the areas of the subjects T _{1 to} T ₇ as shown in FIG. For example, the subject area extraction means 41 extracts a pixel area in which the distance is within a certain range as a subject area constituting the same subject.
After that, the subject area extraction means 41 outputs the extracted subject area to the subject distance calculation means 42 and the viewfinder image generation means 46.

The subject distance calculation means 42 refers to the distance measurement data input from the distance measurement sensor 3, and calculates the distance for each subject area input from the subject area extraction means 41 by a known subject distance calculation method. .. In the present embodiment, the object distance calculating means 42, as shown in FIG. 7, and calculates the distance _d 1 to d ₇ to the object _T 1 through T _7. For example, the subject area extraction means 41 acquires pixels included in the subject area from the distance measurement data, and calculates the average value or the median value of the distances indicated by each pixel as the distance to the subject. Further, the subject area extraction means 41 may obtain a pixel at the position of the center of gravity of the subject area and use the distance indicated by the pixel as the distance to the subject.
After that, the subject distance calculating means 42 generates distance information representing the distance for each subject, and outputs the generated distance information to the subject distance discretizing means 43.

The subject distance discretizing means 43 allocates the focus range of the camera 1 to each subject based on the distance information input from the subject distance calculating means 42 and the interval for each subject determined by the input distance information.
After that, the subject distance discretization means 43 outputs the focus range allocation result to the demand subject selection means 44 and the in-focus subject selection means 45.

<Discretization of focus range>
The discretization of the focus range will be described in detail with reference to FIG. 8 (see FIG. 4 as appropriate).
In FIG. 8, as in FIG. 4, the horizontal axis represents the focus operation value of the focus demand 2, and the vertical axis represents the shooting distance of the camera 1. Further, in FIG. 8, the linear relationship between the focus operation value of the focus demand 2 in FIG. 4 and the shooting distance of the camera 1 is shown by a thick broken line.

Specifically, the subject distance discretizing means 43 is a rear subject located after the attention subject and the attention subject from an intermediate distance between the attention subject to which the focus range is assigned and the front subject located in front of the attention subject. The range up to the intermediate distance between and is assigned as the focus range of the subject of interest.

For example, consider the case where the subject of interest is subject T _2. In this case, the object distance discretizing means 43, the object _{T 2,} and calculates an intermediate distance _{d 1-2} between the object _{T 1} is located in the front one of the object _{T 2.} That is, the intermediate distance d _1-2 is the average value of the subject distances d ₁ and d _2. Furthermore, the object distance discretizing means 43, the object _{T 2,} and calculates an intermediate distance _{d 2-3} between the object _{T 3} located after one of the object _{T 2.} Then, the object distance discretizing unit 43, among all the focus range from MOD to FAR in camera 1, the range of the intermediate distance _{d 1-2} to an intermediate distance _{d 2-3,} focus range of the object _{T 2 R 2} Assign as.

Similar to the subject T ₂ , the subject distance discretizing means 43 sets the range _{from the intermediate distance d 2-3} to the intermediate distance d _{3-4 in} the entire focus range of the camera 1 as the focus range R ₃ of the subject T _3. assign. Further, the subject distance discretizing means 43 similarly assigns the focus ranges R _{4 to} R _{6 of the subjects T 4 to} T _6.

Thus, the focus range _{R i} of the object _{T i,} if the distance to the object _{T i} and _{d i,} is represented by the following equation (1). Here, the subscript i represents the number of each subject T (in the example described in this embodiment, 2 ≦ i ≦ 6). That is, when specifying an arbitrary object distance, the object T _i corresponding to the focus range R _i where the photographing distance belongs, it comes to the nearest object to the photographing distance.
_{d i - (d i -d i} -1) / 2 <R i <d i + (d i + 1 -d i) / 2 ... Equation (1)

Here, the object distance discretizing unit 43, does not separate subject is positioned in front of the object T _1, the range of MOD to the middle distance d _1-2, as the focus range R ₁ of the forwardmost object T ₁ May be assigned.
Further, since the subject distance discretizing means 43 does not position another subject after _{the subject T 7 , the range from the intermediate distance d 6-7} to FAR is assigned as the focus range R ₇ of the rearmost subject T _7. May be good.

In this way, the subject distance discretizing means 43 _{arranges the subjects T 1 to} T ₇ in the order of distance, and discretizes the entire focus range of the camera 1 into the subjects T _{1 to} T _7. That is, in FIG. 8, the entire focus range of the camera 1 is assigned as the focus ranges R _{1 to} R _{7 of the subjects T 1 to} T _{7, respectively.} For example, if the input from the focus demand 2 a focusing operation value (Fig. 8 the horizontal axis) are included in the focus range R _2, shooting distance to be output to the camera 1 (FIG. 8 the vertical axis) is d _2. Further, when the focus operation value input from the focus demand 2 _{is included in the focus range R 3} , the shooting distance output to the camera 1 becomes _{d 3.}

Returning to FIG. 5, the description of the configuration of RAF4 will be continued.
In the demand subject selection means 44, the focus operation value is input from the focus operation value output means 21, and the focus range including the input focus operation value in the focus range for each subject assigned by the subject distance discretization means 43. The subject is selected as the demand subject (first subject). Then, the demand subject selection means 44 outputs the selected demand subject to the viewfinder image generation means 46. Further, the demand subject selection means 44 outputs the shooting distance corresponding to the selected demand subject to the focus command means 47.
The details of the demand subject selection means 44 will be described later.

The focusing subject selection means 45 inputs the current focus value from the lens 15, and in the focus range for each subject assigned by the subject distance discretization means 43, the subject in the focus range including the input current focus value is selected. It is selected as the in-focus subject (second subject). Then, the in-focus subject selection means 45 outputs the selected in-focus subject to the viewfinder image generation means 46.
The details of the focusing subject selection means 45 will be described later.

The viewfinder image generation means 46 reduces the ultra-high-definition image input from the camera body 11 to generate a viewfinder image that highlights at least the demand subject. For example, the viewfinder video generation means 46 down-converts an ultra-high-definition video to a size such as 2K (lower resolution). Then, the viewfinder image generation means 46 outputs the generated viewfinder image to the viewfinder 13.
The details of the image generation means 46 for the viewfinder will be described later.

When the SNAP switch pressing notification is input from the SNAP switch determining means 23, the focus commanding means 47 commands the camera 1 to focus on the demand subject selected when the SNAP switch pressing notification is input. It is a thing. Specifically, when the SNAP switch pressing notification is input, the focus command means 47 outputs the shooting distance corresponding to the demand subject input from the demand subject selection means 44 to the lens 15 as a focus command value.

Hereinafter, the highlight display of the demand subject and the in-focus subject, the focus command for the demand subject, the DETAIL shift, and the enlarged display of the subject will be described in order.
Here, the DETAIL shift means, for example, when the subject is a dog, the focus range is assigned to each part such as the dog's nose, eyes, ears, neck, chest, front legs, and hind legs.

<Highlighting of demand subjects and in-focus subjects>
With reference to FIGS. 9 and 10, the highlighting of the demand subject and the in-focus subject will be specifically described (see FIG. 5 as appropriate).
Here, as shown in FIG. 9, it is assumed that the camera 1 is _{focused on the vicinity of the rearmost subject T 7,} and the cameraman operates the focus demand 2 near the _{frontmost subject T 1.} Further, it is assumed that the subject distance discretizing means 43 discretizes the entire focus range of the camera 1 into the subjects T _{1 to} T _7.
In FIG. 9, illustrate subject T ₁ by hatching, illustrating the subject T ₇ dot.

Demand object selection means 44, the focus operating value output means 21, as a focus operation value, a distance in the vicinity of the object T ₁ is inputted. Therefore, demand object selection means 44, in the focus range of FIG. 8, selecting an object T ₁ as a demand subject. Then, the demand subject selection means 44 outputs the selected subject T ₁ to the viewfinder image generation means 46.

Further, the focusing subject selection means 45 inputs a distance near the _{subject T 7} as the current focus value from the lens 15. Therefore, the in-focus subject selection means 45 selects the subject T ₇ as the in-focus subject in the focus range of FIG. Then, the focusing subject selection means 45 outputs the selected subject T ₇ to the viewfinder image generation means 46.

The viewfinder image generation means 46 reduces the ultra-high-definition image input from the camera body 11 to generate a viewfinder image. At this time, in the viewfinder image generation means 46, the demand subject input from the demand subject selection means 44 and the in-focus subject input from the in-focus subject selection means 45 are the same subject or different subjects. Determine if there is. Then, when the demand subject and the in-focus subject are different subjects in the viewfinder image, the viewfinder image generation means 46 highlights each of the demand subject and the in-focus subject.

In this example, in the viewfinder image generation means 46, the subject T _{1 which is the demand subject and the subject T 7} which is the in-focus subject are different. Therefore, as shown in FIG. 10, each of the subjects T ₁ and T ₇ is used. Highlight. For example, the viewfinder image generation means 46 _{highlights the subject T 1} which is the demand subject in a preset first color (for example, blue), and the subject T ₇ which is the in-focus subject is different from the first color. Highlight in a second color (eg red).
In this way, the cameraman can easily confirm the subject that the camera 1 is actually focusing on and the subject that the camera 1 is trying to focus on with the viewfinder 13.

Here, the viewfinder image generating means 46 refers to the angle of view information input from the lens 15, obtains the trimmed portion on the sensor measurement plane of the distance measuring sensor 3, and overlays the subject T on the subject T. May be good. For example, when the camera 1 zooms in, the viewfinder image generation means 46 enlarges the overlaid highlighting portion according to the angle of view information at that time.

<Focus command to demand subject>
A focus command for a demand subject will be specifically described with reference to FIGS. 11 and 12 (see FIG. 5 as appropriate).
Here, as shown in FIG. 9, in a state where the subject T _{1 is selected as the demand subject and the subject T 7} is selected as the in-focus subject, the cameraman presses the SNAP switch 20A to the subject T ₁ which is the demand subject. It is assumed that the focus has been ordered.

The focus command means 47 receives a SNAP switch pressing notification from the SNAP switch determination means 23. In response to this SNAP switch pressing notification, the focus command means 47 outputs the shooting distance d _{1 of the demand subject (subject T 1} ) input from the demand subject selection means 44 to the lens 15 as a focus command value. Then, as shown in FIG. 11, in accordance with the focus command value, the lens 15 is driven, the camera 1 is focused on the subject T _1. That is, in FIG. 11, demand subject and focusing the object are the same object T _1.
In FIG. 11, illustrating the subject _{T 1} dot.

Therefore, the focusing subject selection means 45 inputs the distance d _{1 of the subject T 1} as the current focus value from the lens 15. Therefore, the focusing object selection means 45, in the focus range of FIG. 8, selecting an object T ₁ as the in-focus object. Then, the focusing subject selection means 45 outputs the selected subject T ₁ to the viewfinder image generation means 46.

In this example, a view finder for video generation unit 46, demand object T ₁ is subject and focusing the subject since the same subject, as shown in FIG. 12, highlights the object T ₁ as the in-focus object. For example, the view finder image generating means 46, the video for the view finder, the second color described above (e.g., red) to highlight the object T ₁ at.
In this way, the cameraman can accurately focus with a simple operation.

<DETAIL shift>
Hereinafter, the DETAIL shift will be specifically described (see FIG. 5 as appropriate).
Here, as shown in FIG. 11, in a state where the camera 1 is focused on the object _{T 1,} cameraman presses the DETAIL switch 20B, and it has commanded the DETAIL shift.

The subject area extraction means 41 and the subject distance calculation means 42 receive a DETAIL switch pressing notification from the DETAIL switch determination means 25. Then, the object area extracting means 41, only the region of the object T ₁ as the object in the distance data inputted from the distance sensor 3, by a well-known subject region extraction method, the object T ₁ by the camera 1 is focused Extract sites (eg, nose, eyes, ears, neck, chest, front legs, hind legs).

Object distance calculating unit 42 refers to the distance data inputted from the distance sensor 3, by a known object distance calculation method, similar to the process for the entire object, part of the subject T ₁ of the object area extracting means 41 extracts Calculate the distance for each.

The subject distance discretizing means 43 inputs distance information for each subject portion in which the camera 1 is focused from the subject distance calculating means 42. Then, the object distance discretizing unit 43, the distance based on the distance each defined object sites the information, similar to the process for the entire object, assigns the focus range of the camera 1 for each portion of the subject T _1. For example, the subject distance discretizing means 43 allocates the entire focus range of FIG. 8 to the focus ranges of the nose, eyes, ears, neck, chest, front legs, and rear legs.

Demand object selection means 44, in the focus range of each part of the object T ₁ of the object distance discretizing means 43 has assigned, similar to the process for the entire object, the object T ₁ corresponding to the focus range that contains the focus operation value Select the part of as the demand subject.

Focusing the object selection means 45, in the focus range of each part of the object distance discretizing means 43 allocated object T _1, similar to the process for the entire object, the object T corresponding to the focus range focus current value is included _{Select part 1 as} the in-focus subject.

Viewfinder for image generation means 46, the video for the view finder, similar to the process for the entire object, highlighting each part of the object T ₁ of the as-demand subject and focusing the subject.

Hereinafter, the relationship between the processing for a plurality of subjects T and the DETAIL shift will be supplemented. Here, the photographer, and to align the focus to the dog's nose as part of the subject T _1.
Since fine adjustment of the focus demand 2 is required, it is difficult to directly focus on the dog's nose. Therefore, the cameraman operates the focus demand 2 _{of the subjects T 1 to} T _{7 , selects the entire subject T 1} (dog) as the demand subject, and presses the SNAP switch 20A. Then, the camera 1 is in focus to the entire object T _1, the video for the view finder 12 is displayed on the viewfinder 13.

Next, the cameraman presses the DETAIL switch 20B. Then, each means of RAF4 performs DETAIL shift, and each part such as the nose, eyes, ears, neck, chest, front legs, and hind legs of the dog can be selected by the focus demand 2. Therefore, the cameraman _{operates the focus demand 2 of each part of the subject T 1} , selects the dog's nose as the demand subject, and presses the SNAP switch 20A. Then, the camera 1 focuses on the dog's nose, and the image for the viewfinder of FIG. 13 is displayed on the viewfinder 13. In FIG. 13, the dog's nose is highlighted as the in-focus subject.
In this way, even a small part such as a dog's nose can be accurately focused by a cameraman with an easy operation.

<Enlarged display of subject>
A magnified display of the subject will be specifically described with reference to FIG. 14 (see FIG. 5 as appropriate).
Here, as shown in FIG. 13, in a state where the camera 1 is in focus to the nose of a dog as a site of the subject T _1, the cameraman depresses the MAG switch 20C, commanded an enlarged display of an object and do.

The viewfinder image generation means 46 receives a MAG switch pressing notification from the MAG switch determination means 27. Then, the viewfinder image generating means 46 enlarges and displays the nose of the dog, which is the in-focus subject, as shown in FIG.
In this way, the cameraman can easily check with the viewfinder 13 whether or not even a small part such as the dog's nose is accurately focused.

(RAF operation)
The operation of RAF4 will be described with reference to FIG. 15 (see FIG. 5 as appropriate).
The subject area extraction means 41 refers to the distance measurement data input from the distance measurement sensor 3, and extracts a subject area from the distance measurement data by a known subject area extraction method (step S1).

The subject distance calculation means 42 refers to the distance measurement data input from the distance measurement sensor 3, calculates the distance for each area of the subject extracted in step S1 by a known subject distance calculation method, and generates distance information. (Step S2).

The subject distance discretizing means 43 discretizes the focus range that can be operated by the focus demand 2 based on the distance for each subject determined by the distance information generated in step S2. That is, the subject distance discretizing means 43 allocates the focus range for each subject (step S3).

The demand subject selection means 44 demands a subject in the focus range in which the focus operation value is input from the focus operation value output means 21 and the input focus operation value is included in the focus range for each subject assigned in step S3. Select as a subject (step S4A).

In the in-focus subject selection means 45, the current focus value is input from the lens 15, and in the focus range for each subject assigned in step S3, the subject in the focus range including the input current focus value is set as the in-focus subject. Select (step S4B).
The execution order of steps S4A and S4B is arbitrary. For example, steps S4A and S4B may be executed at the same time, or step S4A may be executed after step S4B.

When the demand subject and the in-focus subject are the same subject, the viewfinder image generation means 46 generates a viewfinder image in which the same subject is highlighted as the in-focus subject, and the demand subject and the in-focus subject are different subjects. In the case of, a viewfinder image in which each of the demand subject and the in-focus subject is highlighted is generated (step S5).

The focus command means 47 determines whether or not the focus has been commanded based on whether or not the SNAP switch pressing notification has been input from the SNAP switch determination means 23 (step S6).
When the focus is commanded (Yes in step S6), the focus commanding means 47 commands the camera 1 to focus on the demand subject selected when the SNAP switch press notification is input (step S7).
When the focus is not commanded (No in step S6), or after the process of step S7, RAF4 returns to the process of step S1.
In the flowchart of FIG. 15, the RAF 4 repeats the processes of steps S1 to S7, but when the camera 1 finishes shooting, the RAF 4 may also finish the operation.

As described above, the RAF 4 discretizes the focus range that can be operated by the focus demand 2 into a set of distances to the subject, and automatically focuses on the subject closest to the focus operation value input from the focus demand 2. The lens 15 is controlled so as to. As a result, the cameraman can focus the subjects arranged in the order of distance one after another by rotating the focus knob 2A while pressing the SNAP switch 20A. Further, even if the distance to the subject changes, the RAF4 updates the set of distances, so that it is not necessary to track the position that the cameraman wants to focus on as in the conventional case, and the RAF4 automatically tracks the focus position. Here, the accuracy of the distance measurement should be within the range of the depth of field determined by the angle of view of the camera 1, the aperture, the subject distance, and the size of the image sensor.

[Action / Effect]
As described above, the RAF 4 according to the embodiment of the present invention can realize accurate focusing by a simple operation only by selecting the subject to be focused by the cameraman via the familiar focus demand 2.
That is, since the RAF 4 only needs to operate the focus demand 2 that the cameraman is accustomed to, the operation of the cameraman is not complicated and the cameraman does not need time to master the operation.

Further, the RAF4 can accurately focus on a fine part of the subject by performing the DETAIL shift after selecting the subject to be focused on.
Further, the RAF4 can easily confirm whether or not the subject is in focus by enlarging the display of the subject.
Further, the RAF4 does not require a staff member who specializes in focusing, and can reduce the cost required for video production.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and includes design changes and the like within a range that does not deviate from the gist of the present invention.
In the above-described embodiment, the distance is measured by a distance sensor, but the present invention is not limited thereto. For example, in the present invention, the distance may be measured with a stereo camera.

In the above-described embodiment, the subject distance discretizing means has been described as discretizing all subjects, but the present invention is not limited thereto. For example, the subject distance discretizing means may discretize only a preset number of subjects in ascending order of distance.

In the above-described embodiment, the image generating means for the viewfinder has been described as highlighting in a predetermined red or blue color, but the present invention is not limited thereto. For example, the image generating means for the viewfinder may highlight in a color other than red or blue. Further, the image generation means for the viewfinder may be highlighted by peaking processing.

In the above-described embodiment, only the first DETAIL shift has been described, but the second and subsequent DETAIL shifts may be performed. For example, it is assumed that the dog's nose is in focus by the first DETAIL shift. If a second DETAIL shift is performed in this state, the dog's nose tip and mid-abdomen can be focused. By repeatedly performing the DETAIL shift on the same subject in this way, it is possible to focus on a finer part.

In the above embodiments, the RAF has been described as independent hardware, but the present invention is not limited thereto. For example, the present invention can also be realized by a program for coordinating hardware resources such as a CPU, memory, and hard disk of a computer as the RAF described above. This program may be distributed via a communication line, or may be written and distributed on a recording medium such as a CD-ROM or a flash memory.

100 Focus Assist System 1 Camera 11 Camera Body 13 Viewfinder 15 Lens 2 Focus Demand (Focus Control Device)
20A SNAP switch 20B DETAIL switch 20C MAG switch 21 Focus operation value output means 23 SNAP switch judgment means 25 DETAIL switch judgment means 27 MAG switch judgment means 3 Distance measurement sensor 4 Range assist focus controller (focus assist device)
41 Subject area extraction means 42 Subject distance calculation means 43 Subject distance discretization means (focus range allocation means)
44 Demand subject selection means (first subject selection means)
45 Focused subject selection means (second subject selection means)
46 Image generation means for viewfinder 47 Focus command means

Claims (4)

A focus assist device for cameras that has a viewfinder and controls focus with a focus control device.
A focus range assigning means for assigning the focus range of the camera that can be operated by the focus operating device to each subject based on the distance for each subject determined by the input distance information and the input distance information.
A focus operation value is input from the focus operation device, and in the focus range for each subject assigned by the focus range assigning means, a subject in the focus range including the input focus operation value is selected as the first subject. First subject selection means and
A second subject in which the current focus value is input from the camera and the subject in the focus range including the input current focus value is selected as the second subject in the focus range for each subject assigned by the focus range assigning means. Subject selection means and
When a focus confirmation signal is input from the focus operation device, focus command means for instructing the camera to focus on the first subject selected when the focus confirmation signal is input, and
A viewfinder image generation means for reducing the image captured by the camera and generating a viewfinder image in which at least the first subject is highlighted is provided .
The focus range allocation means is intermediate between the attention subject and the rear subject located after the attention subject from an intermediate distance between the attention subject to which the focus range is assigned and the front subject located in front of the attention subject. Assign the range up to the distance as the focus range of the subject of interest,
In the first subject selection means, the focus operation value is input from the focus demand as the focus operation device, and the focus operation value is input.
The focus command means is a focus assist device that commands a camera to focus when a focus determination signal is input from the focus demand. The focus range assigning means inputs the distance information of the subject that the camera is focusing on, and allocates the focus range to each subject portion based on the distance for each subject portion determined by the input distance information.
The first subject selection means selects a subject portion in the focus range including the input focus operation value as the first subject in the focus range for each subject portion assigned by the focus range assigning means. ,
The second subject selection means selects a subject portion in the focus range including the input current focus value as the second subject in the focus range for each subject portion assigned by the focus range assigning means. The focus assist device according to claim 1. When the first subject and the second subject are the same subject, the viewfinder image generation means generates the viewfinder image in which the same subject is highlighted as the first subject, and the first image is generated. The focus assist device according to claim 1 or 2 , wherein when the subject and the second subject are different, the viewfinder image in which the first subject and the second subject are highlighted are generated. .. A focus assist program for causing a computer to function as the focus assist device according to any one of claims 1 to 3.

Images