JP2009092961A - Focusing position control device, focusing position control method, and focusing position control program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve high speed focusing by exerting focus control based on image information. <P>SOLUTION: In order to exert AF control by a contrast detection system, the moving range of a focus lens is limited to a range from a position corresponding to the shortest photographing distance to a position corresponding to a specific photographing distance L meeting a zooming magnification or a diaphragm value at the time. The specific photographing distance L is a limiting position that is obtained when the focus lens is moved to a predetermined position and that is on a front side of a permissible focusing range d that includes infinity capable of obtaining a specific focusing distance wide at a depth D of field or on the front side and on a back side thereof. If focusing condition by the AF control is not obtained with the moving range limited, the focus lens is moved to a position in which the permissible focusing range including infinity can be obtained. Then, all subjects from the photographing distance L to the infinity are brought into focus. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an in-focus position control device, an in-focus position control method, and an in-focus position control program suitable for use in, for example, a digital camera having an autofocus function.

Conventionally, an image pickup apparatus such as a digital camera or a digital video camera that picks up an object using a CCD or MOS type solid-state image pickup device is usually provided with an autofocus function, and a contrast detection method is generally used as an autofocus method. Is. Further, for example, Patent Document 1 below discloses a technique for detecting a human eye in a sequentially captured frame image and setting a focus frame, that is, a focus detection area, at a detected position in autofocus control (AF control). Are listed.
JP 2005-128156 A

  However, in AF control using the contrast detection method, as is well known, a predetermined focus frame is set within the angle of view, and the image information in the focus frame is moved while moving the focus lens in the optical axis direction with a predetermined step width. It is necessary to perform an iterative process such as obtaining an AF evaluation value (such as an integrated value of a high-frequency component) for each position based on.

  Further, as described above, when detecting a specific target object such as a human eye in a frame image for the purpose of setting a focus frame, the number and size of the target objects to be detected are not determined. It is necessary to perform an iterative process of detecting an object while changing the search position in the frame image while gradually changing the size from a small size to a large size.

  Therefore, there is a problem that it takes time to focus by focus control based on image information.

  The present invention has been made in view of such a conventional problem, and an in-focus position control device, an in-focus position control method, an in-focus position control apparatus, and an in-focus position control method capable of achieving high-speed focusing by focus control based on image information. An object is to provide a focal position control program.

  In order to solve the above-mentioned problem, the in-focus position control apparatus according to the first aspect of the present invention is based on an image capturing unit that captures an image of a subject and acquires image information, and an image information acquired by the image capturing unit. Detection means for repeatedly detecting predetermined information required for controlling the focal position while changing the value of a predetermined parameter, adjustment means for automatically adjusting the in-focus position based on the predetermined information detected by the detection means, and the detection As a detection condition when the means detects the predetermined information, a detection condition setting means is provided for setting a detection condition in which a change range of the value of the predetermined parameter is a range corresponding to a current photographing condition for determining optical characteristics. It is characterized by that.

  In the in-focus position control apparatus according to the second aspect of the invention, the detection condition setting means may be configured such that, as the detection condition, the value of the predetermined parameter increases as the depth of field that changes according to the shooting condition increases. A detection condition for narrowing the change range is set.

  In the in-focus position control device according to the third aspect of the invention, when the predetermined information is not detected by the detection operation by the detection unit in accordance with the detection condition set by the detection condition setting unit. The adjustment means includes control means for performing an adjustment operation of moving the focus lens to a predetermined position that secures a shooting distance range including infinity at which the predetermined focusing accuracy is obtained under the shooting conditions. To do.

  Further, in the in-focus position control apparatus according to the invention of claim 4, the predetermined setting set when the detection means detects the predetermined information according to the detection condition set by the detection condition setting means. A specifying unit that specifies a subject distance based on a parameter value of the parameter, and the control unit detects the predetermined information by a detection operation by the detection unit according to a detection condition set by the detection condition setting unit. In this case, the adjusting unit causes the adjusting unit to perform an adjustment operation of the in-focus position for moving the focus lens to a position corresponding to the subject distance specified by the specifying unit.

  In the in-focus position control apparatus according to the fifth aspect of the invention, the photographing condition includes a zoom magnification.

  In the in-focus position control apparatus according to the sixth aspect of the invention, the photographing condition includes an aperture value.

  In the in-focus position control device according to claim 7, the detection condition setting means has a predetermined focus accuracy that can be secured by moving a focus lens to a predetermined position under the photographing condition. On the basis of an imaging distance range including infinity that provides the detection condition, the detection unit sets a detection condition for detecting predetermined information.

  In the in-focus position control apparatus according to the eighth aspect of the invention, the detection means indicates an area corresponding to a human face portion in the image based on the image information acquired by the imaging means. The area information is detected as the predetermined information, and the adjustment means automatically adjusts the in-focus position using the area corresponding to the face portion indicated by the area information detected by the detection means as a focus detection area, and the detection condition The setting means sets a size range of an area corresponding to a face portion to be detected within an angle of view as a detection condition when the detection means detects the area information. In the in-focus position control apparatus according to the ninth aspect of the present invention, the detection means uses the AF evaluation value based on the image information acquired by the imaging means while moving the focus lens as the predetermined information. The adjustment means automatically adjusts the in-focus position by controlling the position of the focus lens to a specific position where the AF evaluation value detected by the detection means reaches a peak, and the detection condition setting means The moving range of the focus lens is set as a detection condition when the detection unit detects the AF evaluation value.

  In the in-focus position control apparatus according to claim 10, the detection condition setting means sets the limit position on the far point side of the movement range of the focus lens to the focus lens in the photographing condition. It is characterized by being set to a position corresponding to a predetermined shooting distance beyond a limit position on the near side of a shooting distance range including infinity that can be secured by moving to a predetermined position and that can obtain a predetermined focusing accuracy. To do.

  In the in-focus position control method according to the eleventh aspect of the present invention, the step of setting the detection condition in accordance with the current photographing condition for determining the optical characteristic and the image pickup means are obtained according to the set detection condition. A step of repeatedly detecting predetermined information required for controlling the in-focus position based on the image information while changing a value of a predetermined parameter, and a step of automatically adjusting the in-focus position based on the detected predetermined information. It is characterized by.

  In the twelfth aspect of the invention, the computer repeatedly detects the predetermined information required for controlling the in-focus position while changing the value of the predetermined parameter based on the image information acquired by the imaging means. Detection means, adjustment means for automatically adjusting the in-focus position based on the predetermined information detected by the detection means, and detection conditions when the detection means detects the predetermined information as current imaging conditions for determining optical characteristics An in-focus position control program for functioning as detection condition setting means that is set accordingly is provided.

  According to the present invention, it is possible to increase the speed of focusing by focus control based on image information.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a digital camera according to the present invention. The digital camera of this embodiment includes an autofocus (AF) function, an automatic exposure (AE) function, and a face detection function based on a contrast detection method, and has the following configuration.

  That is, the lens block 1 is provided with an optical system including a lens group including a shutter 3, a diaphragm 4, a zoom lens 5, and a focus lens 6 provided in a lens barrel 2 of the camera body. The zoom lens 5 and the focus lens 6 can be mechanically moved in the optical axis direction by a drive mechanism (not shown) in the lens barrel 2.

  The lens block 1 includes a shutter actuator 7 for opening and closing the shutter 3, a diaphragm actuator 8 for driving the diaphragm 4, a zoom motor 9 and a focus motor 10 for driving the zoom lens 5 and the focus lens 6 by the driving mechanism, A zoom position detection sensor 11 and a focus position detection sensor 12 are provided for detecting the movement positions of the zoom lens 5 and the focus lens 6, respectively.

  The actuators 7 and 8 and the motors 9 and 10 are provided on the driver block 13 for the iris (Iris), shutter (Shutter), zoom (ZOOM), and focus (Focus) drivers 14 to 14, respectively. 17 is driven.

  The digital camera has a CCD imaging system block 18 comprising a CCD 19, which is an imaging means arranged behind the optical axis of the optical system, a CDS (Correlated Double Sampling) / AD block 20, and a TG (Timing Generator) 21. have.

  When the operation mode is set to the recording mode, the CCD 19 photoelectrically converts the light image of the subject imaged by the optical system and scan-driven by the TG 21 to output a photoelectric conversion output for one screen at a predetermined frame rate. Output. The CDS / AD block 20 performs noise removal by correlated double sampling and conversion to a digital signal with respect to an analog output signal that has been appropriately gain-adjusted for each RGB color component after being output from the CCD 19, and is a color process circuit 22 for output.

  The color process circuit 22 performs color process processing including pixel interpolation processing on the input image pickup signal, generates a digital luminance signal (Y) and color difference signals (Cb, Cr), and controls the entire digital camera. Output to. The CPU 23 is actually a microprocessor having an internal memory, various arithmetic processing circuits, a data input / output interface, and the like.

  The digital signal (image signal) sent to the CPU 23 is temporarily stored in the DRAM 24 as image data and then sent to the image display unit 25. The image display unit 25 includes a video encoder, a VRAM, a liquid crystal monitor, and a drive circuit thereof. A video signal is generated by the video encoder based on a digital signal sent via the CPU 23 and is displayed on the display image based on the video signal, that is, captured on the CCD 19. In addition, a through image of the subject after being thinned to a predetermined number of pixels is displayed on the liquid crystal monitor.

  The key input unit 26 includes various keys such as a power key, a recording / playback mode changeover switch, a shutter key, a zoom key, and a menu key, and sends an operation signal to the CPU 23 according to the key operation by the user. For example, at the time of shooting operation in which the shutter key is pressed in the recording mode, a trigger signal indicating that is output to the CPU 23. The shutter key has a so-called half shutter function that can be operated in two steps, half-press and full-press. The half-press is used for AF lock and AE lock. This is a general configuration used for shooting instructions.

  When the trigger signal is input, the CPU 23 reads out the image data for one screen captured from the CCD 19 in accordance with the trigger signal from the DRAM 24 for each basic unit called a basic block of 8 vertical pixels × 8 horizontal pixels for each of Y, Cb, and Cr components. The compressed data for one image compressed by DCT (Discrete Diffusion Transform) and encoding by the JPEG circuit 27 is stored in the image recording unit 28.

  Specifically, the image recording unit 28 includes a card interface and various nonvolatile memory cards that are connected to the CPU 23 via the card interface and are detachably attached to the camera body. The image data recorded in the image recording unit 28 is read by the CPU 23 in the reproduction mode, expanded by the JPEG circuit 27, and then displayed on the liquid crystal display monitor of the image display unit 25.

  Further, in the recording mode, the CPU 23 causes the lens control block 29 to generate drive signals to be sent to the drivers 14 to 17 of the driver block 13 described above, whereby the aperture of the diaphragm 4, the zoom lens 5 and the focus lens 6. And the opening / closing operation of the shutter 3 are controlled. When the autofocus mode is set as the focus mode, the focus lens 6 is controlled to the in-focus position by the contrast detection method. Further, the position detection information of the lenses 5 and 6 detected by the zoom position detection sensor 11 and the focus position detection sensor 12 is sequentially input to the CPU 23 via the lens control block 29.

  The face detection unit 30 detects a face portion of an arbitrary person in an image captured at a constant period in the recording mode, acquires coordinate information of a region (face region) corresponding to the detected face portion, and sends it to the CPU 23. Output. That is, the face detection unit 30 is a detection unit of the present invention, and specifically includes a temporary storage memory for image data, an image processing circuit, and a plurality of registers for storing parameters used in the face detection operation. In the present embodiment, the face part detection method is a known method based on pattern matching that detects a face part having features similar to a model pattern such as an outline and a color relating to a human face prepared (stored) in advance.

  The flash memory 31 is a non-volatile memory in which stored contents can be rewritten. The flash memory 31 causes the CPU 23 to control the above-described units and perform the processing described later in the recording mode. A focusing position control program and various data for functioning as detection means, adjustment means, detection condition setting means, and control means, and setting information related to various functions of the digital camera set by the user are also stored.

  Next, in the digital camera having the above-described configuration, an operation in a case where a human photographing mode (hereinafter, human photographing mode) prepared in advance as a lower mode of the recording mode is set will be described.

  2 and 3 are flowcharts showing the processing contents of the CPU 23 when the person shooting mode is set. As shown in FIG. 2, the CPU 23 first sets the user shooting mode in advance when the person shooting mode is set. The depth-of-field level set by is read from the flash memory 31 (step S1). This depth of field will be described later. Thereafter, when the shutter button is half-pressed (YES in step S2), the near point of the allowable focus range including infinity according to the current zoom magnification, aperture value, and allowable depth of field is acquired (step). S3).

  Here, the depth-of-field level and the allowable focus range will be described. That is, FIG. 4A is a diagram showing the relationship between the zoom magnification and the depth of field D in the digital camera. As is well known, the depth of field D becomes deeper as the zoom magnification becomes smaller and the wide angle is increased. In a state where a specific subject A at an arbitrary shooting distance is in focus, the depth of field D is shallow in front of the subject A and deep in the back. is there. In addition, the depth of field D has a characteristic that it becomes deeper as the shooting distance becomes longer, and becomes deeper as the aperture of the diaphragm becomes smaller.

  Accordingly, the subject in the range shifted to the front or back of the depth of field D will be out of focus and blur will occur. However, the extent of this is the limit position on the near side and the far side of the depth of field D. Depends on the distance from, and the closer to the limit position, the smaller. In other words, as long as it is within a certain range from the limit position, no problem occurs depending on the purpose of use of the photographed image even if the focus is not completely achieved (even if the focusing accuracy is low).

  The depth-of-field level described above indicates the focusing accuracy that should be ensured at the minimum in the main subject (person) portion of the photographed image based on the above viewpoint, and is automatically set according to the size of the image to be recorded, for example. The user can select from a plurality of levels that can be set according to the purpose of use of the photographed image. The allowable focus range d is a shooting distance range corresponding to the above-mentioned depth of field, and is a range deeper than the depth of field D as shown in FIG.

  In step S3, the current zoom magnification, aperture value, and allowable depth of field level, as well as the limit position on the far side when the shooting distance is changed from a short distance to a long distance, are illustrated. The near point L, which is the photographing distance corresponding to the limit position on the near side of the allowable focusing range d at infinity, is obtained by calculation using a predetermined calculation formula.

  Subsequently, in step S4, based on the current zoom magnification and the near point L of the allowable focusing range d, the minimum face to be detected by the face detection unit 30 from an image captured for each frame (hereinafter referred to as a frame image). The size, that is, the minimum size of the area corresponding to the face portion is determined. The minimum size determined here is the minimum size of the face in the frame image when it is assumed that the distance to the person to be imaged is the near point L of the allowable focus range d. In this way.

  That is, while the minimum size of a general human face is known, the face size in a frame image increases as the zoom magnification increases and the shooting distance decreases (closer), and conversely the zoom magnification. Is smaller and the shooting distance is longer (far). FIG. 5 shows this, and the face in the frame image when the zoom magnification is the maximum (5 in the example in the figure) and the shooting distance is the shortest (the shortest shooting distance, 1 m in the example in the figure). FIG. 6 is a diagram showing a change in the size of a face in a frame image according to a combination of an arbitrary zoom magnification and a shooting distance when the size of the image is used as a reference (100%).

  In step S4, the minimum size of the general human face size prepared based on the above relationship is set as a fixed value, and the current zoom magnification and the near point L of the allowable focusing range d are set as variables. The minimum face size described above is determined (calculated) using a predetermined function formula.

  Thereafter, the CPU 23 sets the current size of the face to be detected from the sequentially acquired frame images to a settable maximum size (step S5), and then performs face detection by the above-described pattern matching. That is, the face detection unit 30 targets each part of the frame image and acquires the degree of coincidence of feature points with the face pattern information (step S6). If the degree of coincidence is not greater than the reference (NO in step S7), the current size of the face to be detected is reduced (step S8), and if the current size is greater than or equal to the minimum size determined in step S4 (step S8). NO in S9), the degree of coincidence is acquired again with the current size.

  Thereafter, the face detection unit 30 is caused to repeatedly reduce the current size of the face to be detected and acquire the feature point coincidence (steps S6 to S8), and reduce the current size of the face to be detected in the meantime. If it is smaller than the minimum size determined in step S4 (YES in step S9), the face detection operation is immediately stopped at that time, and the process proceeds to step S18 in FIG.

  In step S18, the focus lens 6 corresponds to the above-described current zoom magnification, aperture value, and allowable depth of field, and a position where an allowable in-focus range d where the limit position on the back side is infinite is obtained. That is, the lens moves to a position where all the subjects in the range from the near point L to infinity of the allowable focusing range d are in focus.

  Thereafter, when the half-pressed state is released without fully pressing the shutter key (NO in step S19, YES in step S20), the process returns to the above-described step S2 and the above-described processing is repeated. If the shutter key is fully pressed (YES in step S19), in response to this, shooting and shooting image recording processing are performed (step S21), and one shooting operation in the person shooting mode is completed.

  On the other hand, if the degree of coincidence exceeds a reference level before the current size of the face to be detected becomes smaller than the minimum size determined in step S4 (YES in step S7), that is, any position in the frame image If a face portion of the current size set at that time can be detected, a focus frame, that is, a focus detection area, for which an AF evaluation value based on contrast information is acquired in the AF operation described later is set for the face portion. (Step S10). At this time, the focus frame is also displayed on the through image being displayed on the liquid crystal monitor.

  Subsequently, as shown in FIG. 3, the CPU 23 first sets the far limit side limit position of the focus search range (the movement range of the focus lens 6) to a position corresponding to the near point L of the allowable focusing range d described above. Set (step S11). Next, the focus lens 6 is moved to the initial position on the near side of the focus search range (step S12), and the AF evaluation value for the focus frame set in the above-described face portion or the focus frame set in the center of the screen is targeted. Is acquired (step S13).

  If the AF evaluation value peak cannot be confirmed (NO in step S14), the focus lens 6 is moved to the far point side by one step (step S15), and the moved position is the limit position set in step S12. If it does not exceed (NO in step S16), the AF evaluation value is acquired again (step S13).

  Thereafter, the movement of the focus lens 6, the acquisition of the AF evaluation value, and the peak check of the AF evaluation value are repeated (steps S13 to S15), and if the peak of the AF evaluation value can be confirmed during that time (YES in step S14), In other words, if it can be determined that the detected face portion of the person is in focus, the focus lens 6 is fixed at that position (step S17).

  When the focus lens 6 is moved to the far point side by one step and the position exceeds the limit position on the far point side set in step S12 (YES in step S16), a normal operation is immediately performed at that time. The AF process is terminated, and the focus lens 6 corresponds to the above-described current zoom magnification, aperture value, and allowable depth of field, and an allowable in-focus range d where the limit position on the back side is infinite is obtained. The lens is moved to the position, and all the subjects in the range from the near point L to the infinity of the allowable focusing range d are brought into focus (step S18).

  Thereafter, as described above, when the shutter key is not fully pressed and the half-pressed state is released (step S19 is NO, step S20 is YES), the process returns to the above-described step S2, and the processing described above is performed. repeat. If the shutter key is fully pressed (YES in step S19), in response to this, shooting and shooting image recording processing are performed (step S21), and one shooting operation in the person shooting mode is completed.

  As described above, in the human photographing mode, a human face is detected by detecting an arbitrary human face in sequentially captured frame images, setting a focus frame on the detected face portion, and performing AF processing using a contrast detection method. You can focus automatically on the part.

  At that time, in the face detection process, as described above, the minimum size of the face to be detected in the frame image is the near point L of the allowable in-focus range d including the infinite distance to the person to be photographed. The minimum face size is set according to the zoom magnification in the frame image. In other words, the minimum size of the face to be detected is limited to a size determined based on the optical characteristics according to the photographing conditions at that time. Therefore, by reducing the processing for detecting a face smaller than necessary from the frame image, the processing time required for face detection can be shortened, and as a result, focusing can be performed at high speed.

  Further, in the AF processing after setting the focus frame, as described above, the limit position on the far point side of the focus search range (the movement range of the focus lens 6) is set as the allowable limit at which the limit position on the far side becomes infinity. A normal AF control is performed by setting the position in accordance with the near point L of the focus range d, that is, the limit position determined based on the optical characteristics according to the shooting conditions at that time in the far point side of the focus search range. While focusing is performed in the focused state, if the focused state cannot be confirmed (when the peak of the AF evaluation value cannot be confirmed), the focus lens 6 is allowed to be in focus so that the limit position on the far side becomes infinity. By moving to a position where the range d can be obtained, a state where all the subjects in the range from the near point L to the infinity of the allowable focusing range d are in focus is ensured. Therefore, by reducing the focus search range at the time of AF processing, the time required for AF processing itself can be shortened, and focusing can also be performed at high speed.

  Here, in the present embodiment, the limit position on the far point side of the focus search range described above is set to a position corresponding to the near point L of the allowable focusing range d where the limit position on the back side is infinity. However, the present invention is not limited to this, and a position corresponding to an arbitrary shooting distance may be set as long as the shooting distance is at infinity from the near point L. In this case, however, the effect of shortening the time required for the AF process itself is reduced as compared with the present embodiment.

  In the present embodiment, the minimum size of the face to be detected in the face detection process, the limit position on the far point side of the focus search range during normal AF control, and the limit position on the far side are allowed to be infinite. The in-focus range d is set based on the near point L of the imaging processing range in accordance with the current zoom magnification, aperture value, and allowable depth of field. Alternatively, the depth of field D according to the current zoom magnification and aperture value can be used. That is, the allowable depth of field may be set to the maximum level.

  However, using the allowable focus range d as in this embodiment can narrow the face size width to be detected in the face detection process, and the focus search range during normal AF control is narrower. Therefore, focusing can be performed at a higher speed.

  In the present embodiment, the case where the present invention is applied to both the face detection process and the AF process using the face portion detected by the face detection process as a focus frame has been described. The present invention can also be applied to the case where only AF processing using a contrast detection method that is not accompanied is performed, and even in such a case, the time required for AF processing itself can be reduced, and focusing on an arbitrary main subject can be performed at high speed. Can be performed.

  In addition, the face detection process may be performed and the AF process using the detected face portion as a focus frame may be performed as follows. That is, only face detection processing is performed in the same manner as in the present embodiment, and normal AF processing that does not limit the focus search range is performed for AF processing, and the minimum size of the face to be detected is not particularly limited for face detection processing. Ordinary processing may be performed, and only AF processing may be the same processing as in the present embodiment. That is, in the former case, focusing can be performed at high speed by increasing the speed of the face detection process, and in the latter case, focusing can be performed at high speed by increasing the speed of the AF process itself.

  In this embodiment, the iterative process for changing the size of the face to be detected in the face detection process and the iterative process for changing the position of the focus lens in the AF process are executed at different timings. In the above description, the face portion is detected once, and then the detected face portion is set as a focus detection area and the AF operation is performed. Alternatively, the following may be performed.

  That is, the AF process and the face detection process are executed at the same time, and in the repetitive process of changing the position of the focus lens in the AF process, the face size to be detected is designated each time the focus lens is moved to each position. In the meantime, if face detection is successfully performed even before the AF evaluation value reaches its peak, the shooting distance (subject) is determined based on the current face size and zoom magnification. Distance) is specified, the focus lens 6 may be immediately moved to a position corresponding to the specified shooting distance, and the focus lens 6 may be fixed at that position. In such a case, a distance acquisition table indicating the shooting distance corresponding to an arbitrary zoom magnification and an arbitrary face size is prepared in advance, and the CPU 23 is caused to function as the specifying unit of the present invention, and the CPU 23 performs shooting from the distance acquisition table. The distance may be specified.

  In the present embodiment, the case where the face detection process is performed in response to the shutter key being half-pressed has been described. However, the face detection process may be repeatedly performed before the shutter key is half-pressed. .

  In the present embodiment, the face portion of an arbitrary person is detected in the face detection process prior to the setting of the focus frame. However, the present invention is not limited to this. In face detection processing prior to frame setting, face detection including individual identification by pattern matching with the face image may be performed.

  Although the present invention has been described with reference to a case where the present invention is applied to a digital camera having a general configuration, the present invention is not limited thereto, and the present invention is not limited to this as long as focus control based on image information is possible as in a contrast detection method. For example, the present invention can also be applied to other camera devices such as a digital camera built in another information device such as a mobile phone terminal or a digital video camera.

1 is a block diagram of a digital camera according to the present invention. It is a flowchart which shows the processing content of CPU when a person photography mode is set. It is a flowchart following FIG. (A) is a diagram showing the relationship between the zoom magnification and the depth of field, and (b) is a diagram showing the relationship between the zoom magnification and the allowable focus range. It is the figure which showed the change of the size of the face in the frame image according to the combination of zoom magnification and imaging distance.

Explanation of symbols

1 Lens Block 5 Zoom Lens 6 Focus Lens 19 CCD
23 CPU
28 Image recording unit 29 Lens control block 30 Face detection unit 31 Flash memory A Subject D Depth of field d Permissible focus range L Near point

Claims (12)

Imaging means for imaging a subject and acquiring image information;
Detection means for repeatedly detecting predetermined information required for controlling the in-focus position while changing the value of a predetermined parameter based on image information acquired by the imaging means;
Adjusting means for automatically adjusting the in-focus position based on the predetermined information detected by the detecting means;
A detection condition setting means for setting a detection condition in which the change range of the value of the predetermined parameter is set to a range according to a current photographing condition for determining optical characteristics as a detection condition when the detection means detects the predetermined information; An in-focus position control device comprising:   2. The detection condition setting unit, as the detection condition, sets a detection condition in which a change range of the value of the predetermined parameter becomes narrower as a depth of field that changes according to a shooting condition becomes deeper. In-focus position control device.   When the predetermined information is not detected by the detection operation by the detection unit according to the detection condition set by the detection condition setting unit, the adjustment unit has an imaging distance including infinity at which a predetermined focusing accuracy can be obtained. The in-focus position control apparatus according to claim 1, further comprising a control unit that performs an adjustment operation of moving the focus lens to a predetermined position that secures a range in the photographing condition. The detecting means further comprises a specifying means for specifying a subject distance based on a value of a predetermined parameter set when the predetermined information is detected according to the detection condition set by the detection condition setting means;
When the predetermined information is detected by the detection operation by the detection unit according to the detection condition set by the detection condition setting unit, the control unit focuses on a position corresponding to the subject distance specified by the specifying unit. The in-focus position control apparatus according to claim 3, wherein the adjusting means performs an adjustment operation of an in-focus position for moving the lens.   The in-focus position control apparatus according to claim 1, wherein the photographing condition includes a zoom magnification.   The in-focus position control apparatus according to claim 1, wherein the photographing condition includes an aperture value.   The detection condition setting means is configured to detect the predetermined information based on an imaging distance range including infinity that can be obtained by moving a focus lens to a predetermined position under the imaging conditions and that can obtain a predetermined focusing accuracy. The in-focus position control apparatus according to claim 1, wherein a detection condition for detecting a focus is set. The detection means detects, as the predetermined information, area information indicating an area corresponding to a human face part in an image based on the image information acquired by the imaging means,
The adjustment means automatically adjusts the in-focus position using a region corresponding to the face portion indicated by the region information detected by the detection unit as a focus detection area,
The detection condition setting means sets a size range of an area corresponding to a face portion to be detected within an angle of view as a detection condition when the detection means detects the area information. Item 8. The focusing position control device according to any one of Items 1 to 7. The detection means detects an AF evaluation value based on image information acquired by the imaging means as the predetermined information while moving a focus lens,
The adjusting means automatically adjusts the in-focus position by controlling the position of the focus lens to a specific position where the AF evaluation value detected by the detecting means reaches a peak,
The in-focus position according to any one of claims 2 to 7, wherein the detection condition setting unit sets a moving range of the focus lens as a detection condition when the detection unit detects the AF evaluation value. Control device.   The detection condition setting means is capable of securing a limit position on the far point side of the movement range of the focus lens by moving the focus lens to a predetermined position under the photographing condition, and providing an infinite range with a predetermined focusing accuracy. The in-focus position control apparatus according to claim 9, wherein the in-focus position control device is set to a position corresponding to a predetermined shooting distance beyond a limit position on a short distance side of a shooting distance range including far. A step of setting detection conditions according to the current shooting conditions for determining optical characteristics;
A step of repeatedly detecting predetermined information required for controlling the in-focus position based on the image information acquired by the imaging means according to the set detection condition while changing the value of the predetermined parameter;
And a step of automatically adjusting the in-focus position based on the detected predetermined information. Computer
Detecting means for repeatedly detecting predetermined information required for controlling the in-focus position based on image information acquired by the imaging means while changing a value of a predetermined parameter;
Adjusting means for automatically adjusting the in-focus position based on the predetermined information detected by the detecting means;
An in-focus position control program for causing detection conditions when the detection means detects predetermined information to function as detection condition setting means for setting the detection conditions according to the current shooting conditions that determine optical characteristics.

Images