JP2011164428A - Imaging apparatus and control method for the imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique for bringing a subject into focus by appropriately performing focus feeding, even when the focal length to the subject is changed, before and after focus feeding. <P>SOLUTION: A blurred image is generated by applying a blurring filter to an image of the subject (S502). An area most matching with the blurred image in an input image is specified, and a matching degree indicating the degree of matching is obtained (S503 to S508). The blurred image in which the maximum matching degree is calculated, among the formed blurred images, is specified; the blurring filter used for forming the specified blurred image is specified; and then the focal length set with the specified blurring filter is specified (S509). A location in an area that matches most with the specified blurred image in the input image is brought into focus by using the specified focal length. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a focus control technique.

  In moving image shooting, there is a shooting technique called focus feed that intentionally moves the focus from the front subject to the back subject or vice versa. In order to perform such imaging, in film movie and digital cinema shooting, a staff member called a focusman performs focus feed manually by manually performing a focus ring while measuring timing. In order to simplify these operations, for example, as in Patent Document 1, a lens is proposed in which the focus position is manually preset in advance and focused to the focus position preset by the operator's button press operation. As another method, there has been proposed a camera that manually installs two points as in Patent Document 2 and performs focus feed in accordance with a timeline.

Japanese Patent Laid-Open No. 11-248667 JP 2002-139665 A

  However, since all of the above prior arts preset the focus position with respect to the two-dimensional spatial position in the composition, the focus cannot be adjusted when the focal length with respect to the subject changes before and after the focus is sent. . In addition, it is necessary to maintain the focus distance at the time of presetting. For this purpose, it is necessary to fix the angle. For this reason, fixing equipment (such as a tripod) is essential in addition to the camera. Drive control is required.

  The present invention has been made in view of the above problems, and provides a technique for properly performing focus feed and focusing on this subject even if the focal length of the subject changes before and after focus feed. The purpose is to provide.

  In order to achieve the object of the present invention, for example, an imaging apparatus of the present invention comprises the following arrangement. That is, in the imaging apparatus, holding means for holding a set of a focal length and a blur filter preset for the focal length for each different focal length, and image holding for holding an image of a subject And means for generating a blurred image by applying a blur filter in the set to the image of the subject for each set held by the holding means, and an imaging sensor of the imaging device. Generated by the generation unit, an acquisition unit that acquires an input image input to the input unit, a calculation unit that identifies a region that most closely matches the blurred image in the input image, and obtains a degree of matching that indicates the degree of matching Identifying a blur image for which the calculation means has calculated the maximum degree of coincidence among the respective blur images, identifying a blur filter used by the generation means to generate the identified blur image, and The specifying means for specifying the focal length set with the specified blur filter, and the specifying means for the position of the area in the input image that most closely matches the blur image specified by the specifying means And a control means for focusing using the focal length.

  According to the configuration of the present invention, even if the focal length with respect to the subject changes before and after the focus feed, the focus feed can be performed appropriately and the subject can be focused.

FIG. 3 is a block diagram illustrating a functional configuration example of an imaging apparatus. The figure which shows the structural example of GUI. State transition diagram. FIG. 3 is a block diagram illustrating a configuration example of a subject position update unit. 10 is a flowchart of processing performed by the subject position update unit.

  Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. The embodiment described below shows an example when the present invention is specifically implemented, and is one of the specific examples of the configurations described in the claims.

  First, the imaging apparatus according to the present embodiment will be described with reference to FIG. Light (dotted line) from the outside including the subject 199 is converted into an analog signal by the imaging unit 101 including a lens, a shutter, an imaging sensor, and the like. The A / D converter 102 converts this analog signal into a digital signal (image data).

  The signal processing unit 103 performs various processes on the digital signal. The signal processing unit 103 includes an AF, AE, AWB control unit 115, a subject position update unit 116, a color conversion matrix unit 117, and a gamma conversion unit 118.

  The AF, AE, and AWB control unit 115 analyzes the image indicated by the digital signal, and information necessary for the imaging system control unit 110 to perform AF (auto focus), AE (automatic exposure), and AWB (auto white balance). To collect.

  The subject position update unit 116 obtains the position to be focused next in the image indicated by the digital signal, and the focal length with respect to this position. Details of the operation of the subject position update unit 116 will be described later.

  The color conversion matrix unit 117 performs color conversion on the image indicated by the digital signal using the color conversion matrix. The gamma conversion unit 118 performs gamma conversion on the image indicated by the digital signal.

  The D / A converter 104 converts this digital signal into an analog signal. The display unit 114 performs image display based on the analog signal. Thereby, the input image continuously input via the imaging sensor of the imaging device can be displayed on the display unit 114 as a moving image. The display unit 114 can also display characters and windows sent from the character generation unit 112.

  The encoder unit 105 encodes the image data processed by the signal processing unit 103 and sends the encoded result to a medium connected to the RAM 109 or the media I / F (interface) 106.

  The CPU 107 controls the operation of each unit constituting the imaging apparatus. The ROM 108 stores information created in advance, a computer program for causing the CPU 107 to perform operation control of the imaging apparatus, and the like. The RAM 109 has a work area used when the CPU 107 executes various processes, an area for temporarily storing various information, and the like.

  The imaging system control unit 110 performs operation control of the imaging unit 101. The operation unit 111 includes a user interface such as a button group, and the user uses the operation unit 111 to give various input instructions. In the case where the display unit 114 is a touch panel screen, a part of the buttons and sliders included in the operation unit 111 may be displayed on the display unit 114 as an image. In this case, the user operates the button or slider as the displayed image with a finger. The timer 113 performs a timing operation.

  In the present embodiment, using such an imaging apparatus, first, a position for focusing (focusing) and a timing for focusing are set. When this setting is completed, a moving image can be captured. When the moving image is captured, the set position is focused at the set timing.

  Next, setting of a focus adjustment position and focus adjustment timing will be described with reference to FIGS. When the user inputs an instruction to perform “setting of focus position and focus timing setting” using the operation unit 111 in the current state 301 of the imaging apparatus, the CPU 107 changes the state of the imaging apparatus to the state 302. Transition. In the state 302, the CPU 107 causes the display unit 114 to display a GUI (graphical user interface) 200 shown in FIG. In the GUI 200, an image based on analog signals sequentially transmitted from the D / A conversion unit 104 is displayed in the area 201. As a result, in the area 201, an input image continuously input via the imaging sensor of the imaging device is displayed as a moving image. Further, windows 206 and 207 are superimposed and displayed at arbitrary positions on the moving image. The buttons 202, 203, 204, slider 205, and windows 206, 207 are those sent from the character generation unit 112.

  The user can change (specify) the positions of the windows 206 and 207 using the operation unit 111 or directly on the screen. Since the windows 206 and 207 are intended to include an area in which the subject to be focused is shown, the user moves the windows 206 and 207 so as to include an area in which the subject to be focused is shown. . When the CPU 107 detects this movement operation, the CPU 107 changes the state of the imaging apparatus to the state 304. In the state 304, the state value held as the position of the current window 206, 207 is updated to the state value updated by this operation. Of course, this update is not performed if it has not been updated. Then, the state of the imaging device returns to the state 303 again.

  Further, the user uses the slider 205 to set the time from when the subject in the window 206 is focused to when the operation for focusing on the subject in the window 207 (or vice versa) is started. be able to. Specifically, this time can be increased or decreased by moving the adjustment unit 290 of the slider 205 to the left or right using the operation unit 111 or directly on the screen. Upon detecting this operation, the CPU 107 changes the state of the imaging device to the state 306. In the state 306, the state value held as the current set time is updated to the state value updated by this operation. Then, the state of the imaging device returns to the state 303 again.

  When the operation of the windows 206 and 207 and the time setting operation are completed, the user directly instructs the button 202 on the operation unit 111 or the screen. When this instruction is given, the CPU 107 changes the state of the imaging apparatus to the state 305.

  In the state 305, the CPU 107 uses the position of the set windows 206 and 207, the image (subject image) in the windows 206 and 207 (in the area), and the time set using the slider 205 as setting information in the RAM 109 or the like. Store in memory (image retention). Note that it is preferable to use a memory of a type that stores information even when the power of the imaging apparatus is turned off, such as a hard disk.

  In addition, when the user instructs the button 203 directly in the state 303 using the operation unit 111 or on the screen, the state of the imaging apparatus transitions to the state 307, cancels the currently performed operation, and returns to the state 303. .

  In the state 303, when the user directly instructs the button 204 using the operation unit 111 or on the screen, the state of the imaging apparatus is changed to the state 308, and the setting operation using the GUI of FIG. 2 is completed. Accordingly, the moving image displayed in the area 201 is displayed on the display unit 114 instead of the GUI shown in FIG.

  Next, the operation of the subject position update unit 116 will be described with reference to FIGS. In the following description, it is assumed that the imaging apparatus is currently focused on the subject in the window 206.

  First, in step S501, the distance image generation unit 401 acquires an image received from the A / D conversion unit 102 as an input image. Further, the distance image generation unit 401 acquires, as setting information, the position of the window 207, the subject image in the window 207, and the setting time set using the GUI of FIG.

  Here, the ROM 108 has a set of focal lengths and blur filters for reproducing “the degree of blurring at this focal length due to the optical system of the imaging unit 101” for different focal lengths (for example, Between 1 m and 10 m every 1 m). Here, it is assumed that N sets are stored in the ROM 108, the focal length in the set i (1 ≦ i ≦ N) (during the set) is the focal length i, and the blur filter in the set i is installed. Let it be filter i. Such information is known as PSF information.

  In step S502, the distance image generation unit 401 performs processing for generating a blurred image i obtained by applying the blur filter i to the subject image in the window 207 acquired in step S501 for i = 1 to N. As a result, for i = 1 to N, a blurred image i corresponding to the focal length i is generated.

  In step S503, the distance image detection unit 402 initializes the value of the variable i to 1. Then, the distance image detection unit 402 identifies the region (matching region i) that most closely matches the blurred image i in the input image acquired in step S501 by the processing of steps S504 to S506, and matches the input image. The degree of coincidence indicating the position of the region i and the degree of coincidence is obtained.

  Here, the size of the blurred image i in the x direction is S, the size in the y direction is T, the pixel value of the pixel position (α, β) in the blurred image i is Qi (α, β), and the x of the input image The size in the direction is X, the size in the y direction is Y, and the pixel value at the pixel position (α, β) in the input image is P (α, β). In this case, when the upper left corner of the blurred image i is placed at the coordinate position (x, y) on the input image, the area on the input image that overlaps the blurred image i matches the blurred image i. The degree Sp (x, y) is obtained according to the following equation.

  However, in step S504, the distance image detection unit 402 calculates this formula to obtain Sp (x, y). Sp (x, y) is an area on the input image that overlaps with the blurred image i and this blur when the upper left corner of the blurred image i is placed at the coordinate position (x, y) on the input image. A total value of differences for each pixel corresponding to the image i is shown. Of course, the formula for obtaining the degree of coincidence is not limited to this.

  Next, in step S505, the distance image detection unit 402 performs a size comparison between the maximum matching score Si currently held for the blurred image i and the matching score Sp (x, y). As a result of the size comparison, if Si <Sp (x, y), the process proceeds to step S506, and if Si ≧ Sp (x, y), the process proceeds to step S507.

In step S506, the distance image detecting unit 402, Si in Sp (x, y) with by substituting updates ^Si, xm ^i, x respectively ym ^i, by substituting y ^xm i, update ym ⁱ To do.

  In step S507, the distance image detection unit 402 determines whether or not the processing in steps S504 to S506 has been performed for all x and y. As a result of the determination, if the processes of steps S504 to S506 have been performed for all x and y, the process proceeds to step S508. If not, the processes after step S504 are performed for x and y that have not been performed. Do.

When the process proceeds to step S508, the coincidence having the maximum value among the coincidence obtained for each pixel in the input image is stored in Si. The xm ^i, the ym ^i, so that the upper left corner of the coordinate position of the matching region i in the input image is stored.

  In step S508, the distance image detection unit 402 determines whether the processes in steps S504 to S507 have been performed for all i. As a result of this determination, if the processing of steps S504 to S507 has been performed for all i, the processing proceeds to step S509. On the other hand, if the processing of steps S504 to S507 has not been performed for all i, the processing after step S504 is performed for i that has not yet been performed.

In step S509, the subject position update processing unit 403 specifies the maximum value (a value indicating the best match) among S1 to SN. Here, Sj (j is any one of 1 to N) is the maximum value. In this case, the subject position update unit 116 sets the position of the matching area j (an area of the same size as the window 207 where the coordinate position of the upper left corner is xm ^j , ym ^j ) on the input image to the next focus position. As specified. Of course, any position within the matching region j may be specified as the position to be focused.

  In step S509, the subject position update processing unit 403 specifies the focal length j as the focal length for the position to be focused. That is, the focal length set with the blur filter used to generate the “blurred image for which the maximum degree of coincidence is calculated among the generated blur images” is specified.

  Therefore, after the processing according to the flowchart of FIG. 5, when the time set in the GUI of FIG. 2 elapses after focusing in the window 206, the CPU 107 controls the imaging control unit 110 to move to the position of the matching region j. On the other hand, the focal length j is used to focus. This time is counted by the timer 113.

  As described above, according to the present embodiment, it is possible to detect a subject that is not in the focus position, and thus it is possible to focus on a subject whose position dynamically changes.

  In the present embodiment, the number of subjects to be focused on is 2. However, the number of subjects to be focused is not limited to 2, and may be 1 or 3 or more. The GUI shown in FIG. 2 is an example, and the configuration of the GUI is not limited to this as long as the same purpose can be achieved.

Claims (4)

An imaging device,
Holding means for holding a set of a focal length and a blur filter preset for the focal length for each different focal length;
Image holding means for holding an image of a subject;
For each set held by the holding means, generating means for generating a blur image by applying a blur filter in the set to the image of the subject;
Acquisition means for acquiring an input image continuously input via an imaging sensor of the imaging device;
A calculation means for identifying a region that most closely matches the blurred image in the input image, and calculating a matching degree indicating the degree of matching;
Among the profit images generated by the generating means, the profit image for which the calculating means has calculated the maximum degree of coincidence is specified, and the profit used by the generating means to generate the specified profit image. Identifying means for identifying a filter and identifying a focal length set with the identified blur filter;
Control means for focusing on the position of the region that most closely matches the blurred image specified by the specifying means in the input image using the focal length specified by the specifying means. apparatus. Furthermore,
Means for setting a timing at which the control means operates;
The imaging apparatus according to claim 1, wherein the control unit operates at the set timing.   The image holding unit is configured to display an image of a subject appearing in an area designated by a user on an input image acquired by the acquiring unit before the generating unit, the calculating unit, the specifying unit, and the control unit operate. The imaging apparatus according to claim 1, wherein the imaging apparatus is held. Holding means for holding a set of a focal length and a blur filter preset for the focal length for each different focal length;
An image pickup apparatus control method comprising: an image holding unit that holds an image of a subject,
For each set held by the holding means, a generation step of generating a blur image by applying a blur filter in the set to the image of the subject;
An acquisition step of acquiring an input image continuously input via an imaging sensor of the imaging device;
A step of identifying a region most matching the blurred image in the input image, and calculating a matching degree indicating the degree of matching;
The profit image used in the generation process to identify the profit image for which the maximum degree of coincidence was calculated in the calculation process from among the profit images generated in the generation process, and to generate the identified profit image A specifying step of specifying a filter and specifying a focal length set with the specified blur filter;
A control step of focusing on the position of the region that most closely matches the blurred image specified in the specifying step in the input image using the focal length specified in the specifying step. Control method of the device.

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