JP2010266503A - Camera and focus detection area display program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To selectably display at least a part of a plurality of focus points, as a focus point for detecting a focus. <P>SOLUTION: A control section 22 detects the brightness information of a high brightness area detected in a photographing screen and brightness information in each focus point and selectably displays at least a part of the plurality of focus points as the focus point for detecting the focus, based on the result of comparing the brightness information of the high brightness area with the brightness information in each focus detection area. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a camera and a focus detection area display program.

  The following gaze detection devices are known. This line-of-sight detection device automatically detects a focus point intended by a user from a plurality of focus points by detecting a photographer's line of sight and determining a focus point (for example, Patent Document 1). .

JP 2004-129927 A

  However, when a conventional gaze detection device is used to select a focus point intended by the photographer from a plurality of focus points, there is a problem that the configuration of the camera is complicated and the cost is increased. It was.

The camera according to the present invention has a plurality of focus detection areas in a shooting screen, a detection means for detecting brightness information of a high brightness area detected in the shooting screen and brightness information for each focus detection area, and a high brightness Display means for selectively displaying at least a part of the plurality of focus detection areas as a focus detection area for performing focus detection based on a result of comparing the luminance information of the area and the luminance information for each focus detection area; It is characterized by providing.
In the present invention, the plurality of focus detection areas are arranged in a plurality of vertical and horizontal rows in the shooting screen, and the luminance information of the high luminance area is detected in the focus detection area arranged in the uppermost horizontal row in the shooting screen. The luminance information may be included at least.
The camera further includes an operation unit capable of selecting a focus detection region for performing focus adjustment by an operator who operates the camera. The detection unit repeatedly detects luminance information for each focus detection region. Each time detection is performed, the focus detection area to be selectively displayed may be updated, and updating may not be performed while the operation unit is operated by the operator.
While displaying the focus detection area that can be selected by the display means, a confirmation means for confirming whether or not the composition in the photographing screen has changed may be further provided.
The detection unit may divide an area in the shooting screen into a plurality of divided areas, perform photometry, and use the photometric results of the divided areas to detect luminance information of the focus detection area corresponding to the divided areas. .
The display means is configured to selectably display at least a part of the plurality of focus detection areas based on the result of comparing the brightness information of the high brightness area and the brightness information for each focus detection area and the color information. Also good.
A focus detection area display program according to the present invention is based on a detection procedure for detecting information on a field for each focus detection area on a camera having a large number of focus detection areas in a shooting screen, and information on the field. And a display procedure for displaying a plurality of selectable focus detection areas.

  According to the present invention, the focus point intended by the user can be selected with a simple configuration, which is advantageous in terms of cost.

It is a block diagram which shows the structure of one Embodiment of the digital camera in 1st Embodiment. It is a figure which shows the specific example of the focus point frame displayed on the focus point and finder in the imaging | photography screen in 1st Embodiment. It is a flowchart figure which shows the flow of the focus adjustment process in 1st Embodiment. It is a flowchart figure which shows the flow of the focus adjustment process in 2nd Embodiment. It is a figure which shows the specific example of the focus point frame displayed on the focus point and finder in the imaging | photography screen in 2nd Embodiment.

-First embodiment-
FIG. 1 is a block diagram illustrating a configuration of an embodiment of a digital camera according to the first embodiment. The digital camera 100 includes a photographing lens 10, a mirror unit 12, a finder 14, a photometric sensor 15, an image sensor (for example, a CCD) 16, a liquid crystal monitor 18, an operation member 20, a control unit 22, and focus control. Unit 24, ranging unit 26, shutter button 28, and lens communication unit 30.

  The photographing lens 10 includes a focus adjustment lens (AF lens) and a zoom lens (not shown). The taking lens 10 is controlled by the control unit 22 via the focus control unit 24 and the lens communication unit 30. Note that the focus control unit 24 can perform focus adjustment by driving the AF lens based on the control from the control unit 22. The mirror unit 12 includes a main mirror 12a and a sub mirror 12b. The finder 14 includes a prism 14a, a focus point display unit 14b, and a screen 14c.

  In the digital camera 100, light from the subject enters the mirror unit 12 through the photographing lens 10. The subject light incident on the mirror unit 12 is guided to the finder 14 through a path indicated by a broken line before the shutter button 28 is operated (before the release), and is observed by the photographer through the eyepiece. Specifically, the subject light incident on the mirror unit 12 is guided to the finder 14 by the main mirror 12a and forms an image on the screen 14c. The subject light imaged on the screen 14c further passes through the focus point display unit 14b, enters the prism 14a, is reflected by the prism 14a, and is guided to the eyepiece. Further, the subject light is reflected by the prism 14 a and guided to the photometric sensor 15, and photometry is performed by the photometric sensor 15. The photometric sensor 15 divides an area in the shooting screen into a plurality of divided areas and performs photometry, and outputs luminance information and color information obtained by photometry to the control unit 22 as photometric information. Photometry by the photometry sensor 15 is repeated at a predetermined cycle while the shutter button 28 is half-pressed.

  Part of the subject light incident on the mirror unit 12 is reflected downward by the sub-mirror 12 b and enters the distance measuring unit 26. The distance measuring unit 26 measures the distance to the subject based on the incident subject light, and outputs the distance measurement data to the control unit 22. Further, after the shutter button 28 is fully pressed (after release), the subject light incident on the mirror unit 12 is guided to the CCD 16 through a path indicated by a solid line without passing through the main mirror 12a. The CCD 16 captures a subject image on the imaging surface and outputs an image signal to the control unit 22.

  The control unit 22 includes a CPU, a memory, and other peripheral circuits, and controls the entire digital camera 100. Note that the memory constituting the control unit 22 includes SDRAM and flash memory. The SDRAM is a volatile memory, and is used as a work memory for the CPU to develop a program when the program is executed or as a buffer memory for temporarily recording data. The flash memory is a non-volatile memory in which data of a program executed by the control unit 22 and various parameters read during program execution are recorded.

  The control unit 22 performs various image processing on the image signal input from the CCD 16 to generate image data. Further, the control unit 22 performs focus adjustment by performing a focus adjustment process, which will be described later, at the timing when the shutter button 28 is half-pressed during shooting. Note that the digital camera 100 according to the present embodiment has a plurality of focus detection areas (focus points) in the shooting screen as shown in FIG. 2A, and as shown in FIG. 2C. By displaying a frame indicating the focus point (focus point frame) on the focus point display unit 14b, the focus point frame can be superimposed on the subject in the finder 14 and displayed.

  Note that the plurality of focus points in the shooting screen are arranged in a plurality of vertical and horizontal columns in the shooting screen, and in the example shown in FIG. 2A, focus points of m vertical rows × n horizontal rows are arranged. . The position of each focus point in the shooting screen is represented by a horizontal position x and a vertical position y with the lower left in the shooting screen as the origin. For example, the position of the lower left focus point 2a in the shooting screen is represented as (1, 1), and the position of the lower right focus point 2b in the shooting screen is represented as (n, 1). The position of the upper right focus point 2c in the shooting screen is represented as (n, m), and the position of the focus point 2d immediately below the focus point 2c is represented as (n, m-1).

  In the present embodiment, as shown in FIG. 2C, the control unit 22 displays a focus point frame only at a position where there is a high possibility that the subject exists among the plurality of focus points in the shooting screen. The user can select a focus point frame to be used for focus detection from the displayed focus point frames. Then, the control unit 22 performs focus adjustment on the focus point corresponding to the focus point frame selected by the user. Hereinafter, the focus adjustment processing in the present embodiment will be described with reference to FIG.

  FIG. 3 is a flowchart showing the flow of the focus adjustment process in the first embodiment. The process shown in FIG. 3 is executed by the control unit 22 as a program that is activated when the shutter button 28 is half-pressed by the user.

  In step S101, the control unit 22 turns on a half-press timer for measuring the elapsed time after the shutter button 28 is half-pressed, and proceeds to step S102. In step S102, the control unit 22 controls the focus point display unit 14b to place the focus point on the focus point used for focus detection at the previous shooting out of the plurality of focus points in the shooting screen illustrated in FIG. The frame is initially displayed.

  The position information of the focus point used for focus detection at the previous shooting is stored in the flash memory, and the control unit 22 reads the position information from the flash memory, thereby the focus used for focus detection at the previous shooting. The point is specified and the focus point frame is initially displayed. In this embodiment, the focus point frame is initially displayed with the focus point used for focus detection at the time of the previous shooting as an object. However, the focus point frame to be initially displayed is not limited to this. For example, in the shooting screen, The focus point frame may be initially displayed for the focus point arranged at the center.

  Thereafter, the process proceeds to step S103, and the control unit 22 determines whether or not to narrow down the focus point frame to be displayed superimposed on the subject. Whether or not to narrow down the focus point frame is preset by the user on the setting menu, and the control unit 22 makes the determination by referring to the setting value of the corresponding menu item. If a negative determination is made in step S103, the process ends. On the other hand, if a positive determination is made in step S103, the process proceeds to step S104.

  In step S <b> 104, the control unit 22 acquires, from the photometric sensor 15, photometric information corresponding to the focus points arranged in a part of the plurality of focus points arranged in the shooting screen. Then, the control unit 22 calculates an average value (average luminance) BVave of luminance values included in the acquired photometric information. In the present embodiment, the control unit 22 calculates the average luminance BVave corresponding to the focus points arranged in the m column and the m−1 column, which are upper regions in the shooting screen.

Thereafter, the process proceeds to step S105, where the control unit 22 subtracts a predetermined luminance value α set in advance, for example, 2 from the average luminance BVave calculated in step S104, and each of the values arranged in the photographing screen. The magnitude relationship with the brightness value BVxy of the focus point is compared, and it is determined whether or not there is a focus point that satisfies the magnitude relationship represented by the following equation (1).
BVave-α> BVxy (1)

  If a negative determination is made in step S105, it can be determined that there is no region where there is a high possibility that the subject is present in the shooting screen, and the process proceeds to step S107 described later.

  On the other hand, if an affirmative determination is made in step S105, the process proceeds to step S106, and the control unit 22 displays the focus point frame shown in FIG. 2C on the focus point that satisfies the above formula (1). Then, the process proceeds to step S1061. In step S1061, the control unit 22 determines whether or not the processing in steps S105 and S106 has been completed for all focus points in the shooting screen. If a negative determination is made in step S1061, the process returns to step S105. On the other hand, if a positive determination is made in step S1061, the process proceeds to step S107.

  As a result, the focus point frame can be displayed in a range where there is a high possibility that the subject in the shooting screen exists. That is, there is a high possibility that there is a sky in the upper part of the shooting screen such as the m column and the m-1 column shown in FIG. 2A, and the average calculated for such a high luminance region is used. The luminance BVave is a large value. In addition, since the luminance of the area where the subject exists in the shooting screen is likely to be lower than the average luminance BVave calculated for the sky, the luminance value is further higher than the value obtained by subtracting the predetermined luminance value α from the average luminance BVave. It can be determined that there is a high possibility that a subject exists at a focus point with a small BVxy. Therefore, by displaying the focus point frame on the focus point that satisfies the expression (1), the focus point frame can be displayed in a range where there is a high possibility that the subject in the shooting screen is present.

  The user can check the shooting screen on which the focus point frame displayed in step S106 is displayed by looking through the viewfinder 14 through the eyepiece. Then, the user operates the operation member 20 to select one focus point frame displayed on the subject to be focused from among the displayed focus point frames, so that the focus is adjusted by the focus adjustment process. A focus point used for detection can be selected.

  For example, in step S106, the control unit 22 displays the focus point frame in a range where the subject on the shooting screen is highly likely to exist, and selects any one of the focus point frames by default. . The selected focus point frame is displayed with a thicker frame than the other focus point frames, blinking the frame, or displaying in a different color from the other focus point frames. The user can recognize the selected state. Then, the user can switch the focus point being selected by operating the operation member 20.

  In step S107, the control unit 22 determines whether or not the user has changed the composition based on the amount of change in the luminance value BVxy corresponding to each focus point. That is, the total change amount of the calculated brightness values BVxy corresponding to the focus points (1, 1) to (n, m) is detected, and the composition changes if the change amount is equal to or greater than a predetermined value. If the amount of change is less than a predetermined value, it is determined that the composition has not changed. If an affirmative determination is made in step S107, the process returns to step S104 and the process is repeated in order to display a focus point frame in an area where there is a high possibility that the subject is present, with the composition after the change as a target. On the other hand, if a negative determination is made in step S107, the process proceeds to step S108.

  In step S108, the control unit 22 determines whether or not the focus point frame selected by the user among the focus point frames displayed in step S106 has been moved to another focus point frame. If the determination in step S108 is affirmative, there is a possibility that the composition has also changed with the change in the selection of the focus point frame, so the process returns to step S107 and is repeated. On the other hand, if a negative determination is made in step S108, the process proceeds to step S1081.

  In step S1081, the control unit 22 controls the focus control unit 24 to perform focus adjustment processing (AF processing) using the focus point corresponding to the currently selected focus point frame for focus detection, thereby performing focus adjustment. Do. In the focus adjustment processing, focus adjustment is performed by a phase difference method or the like, and detailed description thereof is omitted here. Thereafter, the process proceeds to step S109.

  In step S <b> 109, the control unit 22 determines whether the user has pressed the release button fully to instruct shooting. If a positive determination is made in step S109, the process proceeds to step S1091. In step S1091, shooting processing is performed. For example, the control unit 22 performs various image processing on the image signal input from the CCD 16 to generate image data, and compresses the image data into a predetermined image format such as a JPEG format to generate an image file. Then, it is recorded on a memory card (not shown). Then, it returns to step S107 and repeats a process.

  On the other hand, if a negative determination is made in step S109, the process proceeds to step S110, and the control unit 22 determines that the half-press timer has reached the predetermined time set in advance since the elapsed time since the half-press timer was turned on. Determine whether it is turned off. If a negative determination is made in step S110, the process returns to step S107 and is repeated. On the other hand, when an affirmative determination is made in step S110, the process ends.

According to the first embodiment described above, the following operational effects can be obtained.
(1) The control unit 22 detects the luminance information of the high luminance area detected in the shooting screen and the luminance information for each focus point, and compares the luminance information of the high luminance area with the luminance information for each focus point. Based on the result, at least some of the plurality of focus points are displayed on the focus point display unit 14b so as to be selectable as focus points for focus detection. As a result, the focus point frame can be displayed in a range where there is a high possibility that the subject in the shooting screen exists. In addition, even when there are a large number of focus points, the focus point frame is selectably displayed in a range where there is a high possibility that the subject exists, so that the selection of the focus points does not become complicated.

(2) The plurality of focus points are arranged in a plurality of vertical and horizontal columns (m columns × n columns) in the shooting screen, and m-1 and m−1 on the upper side in the shooting screen are used as luminance information of the high luminance area. Luminance information detected at focus points arranged in a row is used. Since there is a high possibility that there is a sky in the upper part of the shooting screen, if the luminance information is detected for the upper side of the shooting screen, the luminance information of the high-brightness region can be acquired. Further, since the luminance information in the range where the subject is likely to exist is likely to be lower than the luminance information in the high luminance region, the subject existing region in the shooting screen can be specified with high accuracy. The control unit 22 preferably updates information on selectable focus points to be displayed on the focus point display unit 14b every time the photometric sensor 15 performs photometry. As a result, the latest photometric information can be reflected. In addition, it is preferable that the control unit 22 does not change the information on the selectable focus points that are displayed while the user is selecting the focus points. Thereby, the user can select the focus point to the end.

(3) The control unit 22 confirms whether or not the composition in the shooting screen has changed while displaying the selectable focus points on the finder. If the composition has changed, the control unit 22 performs a new process. The focus point frame corresponding to the new composition was displayed. Thus, even when the composition changes during selection of the focus point frame, an appropriate focus point frame can be displayed according to the composition at that time.

(4) The photometric sensor 15 divides the area in the shooting screen into a plurality of divided areas and performs photometry, and the control unit 22 uses the photometric results of the divided areas to calculate the luminance information of the focus points corresponding to the divided areas. It was made to detect. Thereby, the luminance information of each focus point can be detected based on the output from the photometric sensor 15.

-Second embodiment-
In the first embodiment described above, the control unit 22 displays the focus point frame in the shooting screen based on the luminance information included in the photometric information output from the photometric sensor 15 using Expression (1). An example was described. In contrast, in the second embodiment, an example will be described in which the control unit 22 displays a focus point frame on the shooting screen based on color information included in the photometric information output from the photometric sensor 15. In the second embodiment, the block diagram shown in FIG. 1 and the diagrams showing the focus points and focus point frames shown in FIGS. 2A and 2B are the same as those in the first embodiment. The description is omitted for the same reason.

  FIG. 4 is a flowchart showing a flow of focus adjustment processing in the second embodiment. The process shown in FIG. 4 is executed by the control unit 22 as a program that is activated when the shutter button 28 is half-pressed by the user. In FIG. 4, steps having the same processing contents as those in the flowchart in the first embodiment shown in FIG. 3 are given the same step numbers and description thereof is omitted, and the difference from FIG. 3 is mainly described. explain.

  In step S204, the control unit 22 acquires photometric information corresponding to all (m × n) of the plurality of focus points arranged in the photographing screen from the photometric sensor 15, and based on the color information included in the photometric information. The color calculation is performed for each focus point. Specifically, the control unit 22 performs color calculation for each focus point by performing conversion from the RGB color system to the L * a * b * color system. Thereafter, the process proceeds to step S205.

  In step S205, the control unit 22 determines whether or not there is a focus point where the skin color is detected based on the color information calculated in step S204. In the present embodiment, the control unit 22 is in the middle of the + a * direction (red direction) of the a * axis and the + b direction (yellow direction) of the b * axis in the L * a * b * color system, for example, 45. A color distributed within a predetermined range is determined as a skin color, and it is determined whether or not there is at least one focus point where the skin color is detected among the focus points in the shooting screen.

  If a negative determination is made in step S205, the process proceeds to step S107. If an affirmative determination is made, the process proceeds to step S106. In step S106, the control unit 22 displays a focus point frame on the focus point where the skin color is detected, and the process proceeds to step S1061. Accordingly, the focus point frame can be displayed at a location where the skin color of a person who is likely to be the main subject is detected. For example, as shown in FIG. 5, a focus point frame can be displayed at a position where a person's face is present, and the user can select one focus point frame displayed on the subject to be focused from. By selecting, the focus point used for focus detection in the focus adjustment process can be selected.

  According to the second embodiment described above, the control unit 22 displays at least some of the plurality of focus points in a selectable manner based on the color information of each focus point. As a result, it is possible to display the focus point frame at a location where the skin color of a person who is highly likely to be the main subject is detected, even in the range where the subject within the shooting screen is likely to exist. . The control unit 22 compares the luminance information of the high luminance area and the luminance information for each focus point, narrows down the range where the subject is likely to exist, and then further determines the skin color area based on the color information. It is good also as narrowing down to a focus point.

-Modification-
The digital camera according to the above-described embodiment can be modified as follows.
(1) In the first and second embodiments described above, when the composition changes, the control unit 22 performs a new process to display the focus point frame corresponding to the new composition. did. However, the control unit 22 may not update the focus point frame while the operation member 20 is being operated by the user even when the composition changes.

(2) In the first and second embodiments described above, an example in which the control unit 22 estimates the subject position in the shooting screen and displays the focus point frame based on the detection result by the photometric sensor 15 will be described. did. However, a temperature sensor or a sound sensor may be mounted on the digital camera 100, and the control unit 22 may estimate the subject position in the shooting screen based on the temperature sensor or the sound sensor. For example, based on the output of the temperature sensor, a range in which the temperature is close to the body temperature of the person in the shooting screen may be estimated as the subject position, or based on the output of the sound sensor, the vicinity of the sound generation source May be estimated.

(3) In the first and second embodiments described above, the control unit 22 displays the focus point frame on the focus point display unit 14b, thereby superimposing the focus point frame on the subject in the finder 14. The example to display was demonstrated. However, when a through image is displayed on the liquid crystal monitor 18, the control unit 22 may display the focus point frame superimposed on the through image on the liquid crystal monitor 18.
(4) In the first and second embodiments described above, the control unit 22 takes into account that there is a high possibility that a high-luminance sky exists in the upper part of the shooting screen. An example has been described in which the average luminance BVave corresponding to the focus points arranged in the m-th column and the m-1th column, which are the upper regions of, is calculated. However, the average luminance BVave may be calculated for only the uppermost m columns as the upper region in the shooting screen, or the average luminance BVave may be calculated for the m to m-2 columns. May be. In other words, the average luminance BVave may be calculated by determining an area including at least the uppermost m column as a high luminance area. In addition, depending on the shooting scene, the upper part of the shooting screen is not necessarily a high-brightness area, so the high-brightness area that is the target for calculating the average luminance BVave may be changed according to the shooting scene.

(5) In 2nd Embodiment mentioned above, the control part 22 demonstrated the example which displays a focus point frame on the focus point from which the skin color was detected based on the calculation result of the color information in each focus point. However, since the color of the subject that the user wants to focus on is not necessarily a skin color, the user may arbitrarily set the color to be displayed in the focus point frame. In this case, in step S205 in FIG. 4, the control unit 22 determines whether or not there is a focus point where the color set by the user is detected in the shooting screen. If there is, the control unit 22 sets the focus point. A focus point frame may be displayed as a target.

(6) In the above-described first and second embodiments, the example in which the present invention is applied to the digital camera 100 has been described. However, the present invention is also applicable to other devices having a focus adjustment function, such as a mobile phone with a camera.

  Note that the present invention is not limited to the configurations in the above-described embodiments as long as the characteristic functions of the present invention are not impaired. Moreover, it is good also as a structure which combined the above-mentioned embodiment and a some modification.

DESCRIPTION OF SYMBOLS 100 Digital camera, 10 Shooting lens, 12 Mirror part, 12a Main mirror, 12b Sub mirror, 14 Finder, 14a Prism, 14b Focus point display part, 14c Screen, 15 Photometric sensor, 16 CCD, 18 Liquid crystal monitor, 20 Operation member, 22 Control unit, 24 Focus control unit, 26 Distance measuring unit, 28 Shutter button, 30 Lens communication unit

Claims (7)

A camera having a plurality of focus detection areas in a shooting screen,
Detecting means for detecting luminance information of the high luminance area detected in the photographing screen and luminance information for each focus detection area;
Based on the result of comparing the luminance information of the high luminance area and the luminance information for each focus detection area, at least a part of the plurality of focus detection areas is used as the focus detection area for performing focus detection. A camera comprising: display means for displaying selectably. The camera of claim 1,
The plurality of focus detection areas are arranged in rows and columns in the shooting screen,
The camera according to claim 1, wherein the luminance information of the high luminance area includes at least the luminance information detected in the focus detection area arranged in the uppermost horizontal row in the photographing screen. The camera according to claim 1 or 2,
An operating means capable of selecting the focus detection area for performing the focus adjustment by an operator operating the camera;
The detection means repeatedly detects luminance information for each focus detection area,
The display means updates the focus detection area to be selectively displayed every time the detection means performs the detection, and does not perform the update while the operation means is operated by the operator. Camera characterized by. The camera according to any one of claims 1 to 3,
The camera further comprising: a confirmation unit configured to confirm whether or not the composition in the photographing screen has changed while the focus detection area selectable by the display unit is displayed. In the camera according to any one of claims 1 to 4,
The detecting means divides an area in the shooting screen into a plurality of divided areas and performs photometry, and uses the photometric results of the divided areas to detect luminance information of the focus detection area corresponding to the divided areas. Camera characterized by. In the camera according to any one of claims 1 to 5,
The display means can select at least a part of the plurality of focus detection regions based on a result of comparing the luminance information of the high luminance region and the luminance information of each focus detection region and color information. A camera characterized by being displayed on the screen. For cameras with multiple focus detection areas in the shooting screen,
The brightness information of the high brightness area detected in the shooting screen and the brightness information of each previous focus detection area are detected,
Based on the result of comparing the luminance information of the high luminance area and the luminance information for each focus detection area, at least a part of the plurality of focus detection areas is used as the focus detection area for performing focus adjustment. A focus detection area display program for display in a selectable manner.

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