JP6548435B2 - Display control apparatus, control method therefor, and imaging apparatus - Google Patents

Description

  The present invention relates to a display control apparatus that performs display control of a focus state at the time of manual focus adjustment, a control method thereof, and an imaging apparatus.

  Focusing devices such as high-definition video cameras compatible with full high-definition cameras and 4K in recent years have higher resolution than before, and when the photographer focuses on an object by manual focus operation (MF operation), strict focus adjustment It is not easy to do. In particular, when performing an MF operation while confirming with a viewfinder or display panel or the like mounted on the camera, a shift in focus may occur to an extent that can not be confirmed with the viewfinder or display panel or the like. It is difficult to judge if

  Therefore, a focus assist method for assisting MF operation has been proposed. Patent Document 1 proposes a method of calculating a focus evaluation value at the time of MF operation and displaying a focus degree on a bar. Further, Patent Document 2 proposes, as a focus assist method in an imaging apparatus, a plurality of display methods representing a change in focus state caused by the movement of a focus lens. Further, Patent Document 3 proposes a method of changing the display time of the display of the focus state in accordance with the operation of the focus lens.

Japanese Patent Application Publication No. 2007-248615 JP, 2005-140943, A JP, 2009-122593, A

  In the conventional focus assist method as described above, for example, when the user moves the focus detection area, a problem occurs that the focus detection result is not stable due to a change in the pattern in the focus detection area. In that case, the index of the display of the focus state does not change smoothly, which hinders the user's focus operation. However, none of Patent Documents 1 to 3 takes into consideration the case where the position of the focus detection area changes.

  As described above, when the user moves the focus detection area, the index of the display of the focus state does not change smoothly due to the change of the pattern in the focus detection area. In addition, when the focus detection area is not moved, it is possible to stabilize the focus detection result by averaging a plurality of focus detection results acquired in the past, but when the focus detection area is moved, If the average is taken, the responsiveness of the display will decrease.

  The present invention has been made in view of the above problems, and has as its object to perform focus assist display in which stability and responsiveness for supporting a user's focusing operation at the time of manual focusing are compatible.

In order to achieve the above object, the present invention is a display control device for displaying on a display means an image based on a signal generated by an imaging means for receiving and photoelectrically converting a light flux incident through an imaging optical system. Focus detection means for repeatedly detecting a focus state based on a pair of image signals output from the focus detection area set in the light receiving area of the imaging means, and the focus state detected by the focus detection means Display control means for superimposing the index based on the image on the image and displaying it on the display means, and designation means for receiving an operation for designating the position of the focus detection area, the display control means comprising the designation means The responsiveness of the display of the indicator to the detection result of the focus state by the focus detection means is changed according to the amount of change of the position of the focus detection area designated via the display.

  According to the present invention, it is possible to realize a focus assist display having both stability and responsiveness for assisting the user in focusing operation at the time of manual focusing.

BRIEF DESCRIPTION OF THE DRAWINGS The block diagram which shows schematic structure of the imaging system in embodiment of this invention. Schematic of the pixel array of the image pick-up element in embodiment. FIG. 6 is a view showing an example of focus assist display in the present embodiment. FIG. 6 is a view showing the relationship between the amount of movement of a focus detection area and focus assist display in the present embodiment. 5 is a flowchart showing a main flow of focus assist display control in the present embodiment. FIG. 6 is a view for explaining setting processing of a focus detection area in the present embodiment. 6 is a flowchart illustrating an example of focus detection area setting processing according to the present embodiment. 5 is a flowchart showing focus detection processing in the present embodiment. FIG. 3 is a view showing an example of an image signal obtained from a focus detection area in the present embodiment. FIG. 6 is a diagram for explaining a correlation calculation method in the present embodiment. FIG. 6 is a diagram for explaining a correlation calculation method in the present embodiment. 6 is a flowchart showing focus detection result averaging processing in the present embodiment. 6 is a flowchart showing angle index calculation processing in the present embodiment. 6 is a flowchart showing direction index calculation processing in the present embodiment. FIG. 6 is a view showing an example of additional setting of a focus detection area at the time of subject detection in the present embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. The embodiment described below is an example as a realization means of the present invention, and it should be appropriately corrected or changed according to the configuration of the apparatus to which the present invention is applied and various conditions. It is not limited to the embodiment of the invention.

Configuration of Imaging System FIG. 1 is a block diagram showing a schematic configuration of an imaging system provided with a focus assist function according to an embodiment of the present invention. In addition, in this embodiment, although demonstrated as a lens exchangeable imaging system, it may be an imaging device which has a fixed lens.

  As shown in FIG. 1, the imaging system in the present embodiment is composed of a lens unit 10 and a camera body 20. A lens control unit 106 that generally controls the operation of the entire lens unit 10 and a camera control unit 207 that generally controls the operation of the entire imaging system communicate data.

  First, the configuration of the lens unit 10 will be described. The lens unit 10 has an imaging optical system including a fixed lens 101, an aperture 102, a focus lens 103, a zoom lens (not shown), and the like. The diaphragm 102 is driven by the diaphragm driving unit 104, and controls the amount of light incident on the image sensor 201 described later. The focus lens 103 is driven by the focus lens drive unit 105 and used for focusing. The zoom lens (not shown) is used for zoom adjustment by being driven by a zoom lens drive unit. In the present embodiment, the zoom lens and the zoom lens drive unit are not essential components, and may be omitted.

  The diaphragm drive unit 104, the focus lens drive unit 105, and the zoom lens drive unit are controlled by the lens control unit 106, and the aperture diameter of the diaphragm 102 and the positions of the focus lens 103 and the zoom lens are controlled. When an operation such as focusing or zooming is performed by the user operating the focus ring or the zoom ring provided in the lens operation unit 107, the lens control unit 106 performs control according to the user operation. The lens control unit 106 controls the diaphragm drive unit 104, the focus lens drive unit 105, and the zoom lens drive unit according to control commands and control information received from a camera control unit 207 described later, and controls the camera for lens information. Send to the unit 207.

  Next, the configuration of the camera body 20 provided with the focus assist function according to the present embodiment will be described. In the camera body 20, the imaging device 201 is formed of a CCD or a CMOS sensor, and a light flux passing through the imaging optical system of the lens unit 10 is imaged on the light receiving surface of the imaging device 201. Then, the formed object image is photoelectrically converted by the photodiode (photoelectric conversion unit) of the imaging device 201 into a charge corresponding to the amount of incident light, and is stored. The charge stored in each photodiode is sequentially read out from the imaging device 201 as a voltage signal corresponding to the charge based on the drive pulse supplied from the timing generator 209 in accordance with an instruction from the camera control unit 207. Although the detailed configuration of the imaging device 201 will be described later, the imaging device 201 in this embodiment outputs a pair of focusing signals that can be used for phase difference focus detection in addition to a normal imaging signal. be able to.

  The imaging signal and the focusing signal read out from the imaging element 201 are input to the CDS / AGC circuit 202, and correlated double sampling for removing reset noise, adjustment of gain, and digitization of a signal are performed. The CDS / AGC circuit 202 outputs the processed imaging signal to the camera signal processing unit 203 and the subject detection unit 210, and the focusing signal to the focusing signal processing unit 204.

  The camera signal processing unit 203 performs various types of image processing on the imaging signal output from the CDS / AGC circuit 202 to generate a video signal. The display unit 205 is a display device such as an LCD or an organic EL, and displays an image based on the video signal output from the camera signal processing unit 203. In the recording mode for recording an imaging signal, the imaging signal is sent from the camera signal processing unit 203 to the recording unit 206, and is recorded on a recording medium such as an optical disk, a semiconductor memory, a magnetic tape, or the like.

  The focus signal processing unit 204 performs correlation calculation based on the pair of focusing signals output from the CDS / AGC circuit 202, and the defocus amount and reliability information (two-image coincidence, two-image steepness, contrast information, Calculate saturation information, flaw information, etc.). Then, the calculated defocus amount and reliability information are output to the camera control unit 207. The details of the correlation calculation will be described later with reference to FIGS. 9 and 10.

  The camera control unit 207 performs control by exchanging information with each component in the camera body 20. In addition to the processing in the camera body 20, power ON / OFF, setting change, and recording are controlled according to an input from the camera operation unit 208 operated by the user. Furthermore, various functions are performed according to the user's operation, such as switching between autofocus (AF) / manual focus (MF) control, confirmation of a recorded image, and selection of a focus detection area. Further, as described above, information is exchanged with the lens control unit 106 in the lens unit 10, and a control instruction and control information of the photographing optical system are transmitted, and information in the lens unit 10 is acquired.

  The subject detection unit 210 performs known detection processing on the imaging signal output from the CDS / AGC circuit 202, and detects a specific subject area from the photographing screen such as face detection or human body detection. In addition, at the time of face detection, the face direction (front, sideways, backward) is also detected. In the following description, it is assumed that the face of a person is detected as a subject.

Configuration of Image Pickup Element FIG. 2 is a diagram showing an outline of a pixel array of the image pickup element 201 in the present embodiment. FIG. 2 shows the pixel array of the two-dimensional CMOS sensor used as the imaging element 201 in this embodiment in a range of 4 columns × 4 rows of imaging pixels (a range of 8 columns × 4 rows as an array of focus detection pixels) It is shown by.

  In the present embodiment, it is assumed that the pixel group 200 consists of 2 columns × 2 rows of pixels and is covered by a Bayer-arranged color filter. Then, in each pixel group 200, the pixel 200R having R (red) spectral sensitivity is at the upper left position, and the pixel 200 G having G (green) spectral sensitivity is at the upper right and lower left positions. A pixel 200B having sensitivity is disposed at the lower right position. Furthermore, in order to perform focus detection in the imaging surface phase difference method, the imaging device 201 according to the present embodiment holds a plurality of photodiodes (photoelectric conversion units) with respect to one microlens 215. . In this embodiment, it is assumed that each pixel is constituted by two photodiodes 211 and 212 arranged in 2 columns × 1 row.

  The image pickup element 201 acquires a large number of image pickup signals and a signal for focusing by arranging a large number of pixel groups 200 consisting of 4 columns × 4 rows of pixels (8 columns × 4 rows of photodiodes) shown in FIG. Is possible.

  In each pixel having such a configuration, the light flux is separated by the microlens 215 and is imaged on the photodiodes 211 and 212. Then, a signal (A + B signal) obtained by adding the signals from the two photodiodes 211 and 212 is used as an imaging signal, and two signals (A and B image signals) read from the respective photodiodes 211 and 212 as focusing signals. Use. Note that although the imaging signal and the focusing signal may be read out respectively, in the present embodiment, the processing load may be taken into consideration as follows. That is, the imaging signal (A + B signal) and the focusing signal (for example, A signal) of one of the photodiodes 211 and 212 are read out, and the other focusing signal (for example, B signal) is obtained by taking the difference. get.

  In the present embodiment, in each pixel, one micro lens 215 is configured to have two photodiodes 211 and 212, but the number of photodiodes is not limited to two, and may be more than two. Good. Further, a plurality of pixels in which the opening position of the light receiving unit is different from the microlens 215 may be provided. That is, any configuration may be employed as long as two signals for phase difference detection, such as A image signal and B image signal, can be obtained as a result. Further, the present invention is not limited to the configuration in which all the pixels have a plurality of photodiodes as shown in FIG. 2, but the focus detection pixels as shown in FIG. It may be provided in

Display Form of Focus Assist Next, a display mode of focus assist in the present embodiment will be described with reference to FIGS. 3 and 4. FIG. 3A shows an example of the focus assist display 300 representing the focus state. A focus detection area 301 indicates an area for detecting a focus state, and the display parts 302 to 305 express the detected focus state. When the focus assist display is performed, each display part is displayed on the display unit 205 so as to be superimposed on the image.

  The angle display part 302 is an index indicating the distance to the in-focus position (corresponding to the defocus amount), and the in-focus position display part 303 indicates the in-focus position. The angle display part 302 moves along the circular part 304 in accordance with the focus state, and is displayed at the same position as the in-focus position display part 303 when focused. Further, in the case of focusing, the color of each display part may be different from that in the case of not focusing. The angle formed by the angle display part 302 and the in-focus position display part 303 changes in accordance with the focus detection result (defocus amount) acquired from the focus detection area 301. Further, the direction display part 305 is an index indicating the direction to the in-focus state. This represents whether the image is blurred to the near side or to the infinite side with respect to the in-focus position. As described above, the focus state display is performed by the display part indicating the distance to the in-focus state, the direction, and the in-focus state.

  The focus assist display 300 configured as described above changes the state as shown in FIG. 3B in order to notify the user whether it is in focus or not. First, in the case where the focus lens 103 is far from the in-focus position (large blur) and in the case close to the in-focus position (small blur), the in-focus position display part 303 and the angle display part 302 Change the angle you make. That is, as shown in FIG. 3B, the distance from the in-focus position is notified to the user by setting the angle θ1 at the large blur to be larger than the angle θ2 at the small blur. Note that this angle changes smoothly in accordance with the focus state, and at the time of focusing, the angle display part 302 indicating the angle and the focus position display part 303 are displayed in an overlapping manner. Furthermore, the display color and thickness of the circular part 304 may be changed.

  When the distance to the in-focus position (defocus amount) can not be used and only the in-focus direction can be used, the direction display part 305 is displayed without displaying the angle display part 302. If neither the distance to the in-focus position nor the direction can be used, both the angle display part 302 and the direction display part 305 are not displayed, indicating that distance measurement is not possible. In this case, the color and shape of the focus detection area 301 and / or the circular part 304 may be changed.

Whether or not the distance and direction to the in-focus position can be used may be determined based on the reliability of the focusing signal. For example, if the reliability is higher than the first threshold, it is determined that both the distance to the in-focus position and the direction can be used. If the reliability is less than the first threshold and higher than the second threshold, it is determined that only the in-focus direction can be used. If the reliability is less than or equal to the second threshold, it is determined that neither the distance to the in-focus position nor the direction can be used.
Note that these focus assist displays are an example, and the present invention is not limited to these display forms.

  Further, the focus assist display 300 can be moved to any position designated by the user by a touch operation on the display unit 205 or a cross key (not shown). In addition, it is desirable to automatically display in a characteristic part at the time of subject detection. For example, when the subject 307 is detected, as shown in FIG. 3C, the focus assist display 300 is displayed on the subject 307 (person's The face is automatically placed at the eye or nose position, which is a characteristic part of the face.

  Here, when the user moves the focus detection area 301 or when the focus assist display 300 is automatically performed in the subject, the focus detection result is not stable due to a change in the design in the focus detection area 301, etc. The problem of In that case, the angle display part 302 and the direction display part 305 do not change smoothly and give the user a sense of anxiety in the focus operation. Therefore, the stability of the display 300 can be improved by averaging and using the results of focus detection performed a plurality of times. However, although the display of the angle display part 302 and the direction display part 305 is stable, when the focus detection area is moved by using the average value, the subject is detected in the past when the subject changes. Responsiveness is lost due to the use of data.

  Therefore, in the present embodiment, as shown in FIG. 4, the focus assist display control is changed according to the amount of change (the amount of movement) of the position of the focus detection area. As an example, in the present embodiment, the contents (items) of the focus assist display, the average number of times of focus detection results used for angle display, the position of the focus detection area, and the like are changed. In addition, focus assist display control is changed between manual movement and automatic movement (when an object is detected).

  When the focus detection area is moved manually, the movement of the focus detection area is roughly divided into three patterns. The determination of the amount of change in the position of the focus detection area is made based on the overlapping rate of the focus detection area at the time of the previous detection of the focus state and the detection of the current focus state. If the overlap rate is 100 to 80% (the amount of change is less than the second amount), "no movement", if the overlap rate is 80 to 50% (the amount of change is greater than the second amount, less than the first amount ) Is determined to be "moving small (speed small)". Further, when the overlapping rate is 50 to 0% (the amount of change is larger than the first amount), it is determined as "moving large (speed large)". In addition, since focus detection is repeatedly performed in a predetermined cycle, the case where the amount of change (the amount of movement) of the focus detection area is large can be said to be the case where the moving speed of the focus detection area is large. As described above, in the present embodiment, the change in the position of the focus detection area at the time of the previous focus detection and the current focus detection is determined, and focus assist control is changed as described later based on the determination result. Specifically, as the change in the position of the focus detection area is larger, the responsiveness of the focus assist display is increased.

  In the case of "no movement" and "small movement", the results of detection of the focus state a plurality of times are averaged, and focus assist display indicating "angle" and "direction" is performed based on the averaged result. Here, the "angle" corresponds to the defocus amount, and the "direction" corresponds to the direction to focus. Further, in the case of “small movement”, the responsiveness of the focus assist display is enhanced by reducing the number of times of averaging the detection results of the focus state as compared with the case of “no movement”.

  As shown in FIG. 4, in the case of "no movement", stable display is realized with the display content being "angle" and "direction" and the average number of focus detection results used for angle display being 10 times. In the case of "small movement", the display content is "angle" and "direction", and the average number of focus detection results used for angle display is five times, compared to "no movement". Emphasis on responsiveness rather than stable display.

  Further, in the case of “moving large”, the display content is only “direction”, and the average calculation processing of the focus detection results used for angle display is not performed. This is because when the amount of movement is large, there is a possibility that the focus detection results for different subjects in the past may be used if the focus detection results for a plurality of cycles are averaged. Therefore, without averaging the focus detection results, the value obtained based on the focusing signal obtained from the moved focus detection area is used as it is for focus assist display. However, in this case, since the angle display indicating the distance (the defocus amount) to the in-focus position becomes unstable, the angle display is not performed but only the direction display. This is because in the case of “moving large”, the user may be changing the subject, and therefore it is less complicated on the screen to display the angle rather than displaying the unstable and unnecessary display. It is because it can.

  On the other hand, in the case of automatically moving the focus detection area at the time of object detection or the like, the display content is set to “angle” and “direction”. Although average calculation processing of focus detection results used for angle display is not performed, angle display and direction display are performed using focus detection results in a plurality of focus detection areas set as described later in the detected subject. Do.

  As described above, when it is determined whether or not the distance and direction to the in-focus position can be used based on the reliability of the focusing signal, etc., the display content is determined with priority given to the determination result. Do. That is, when both the distance to the in-focus position and the direction can not be used, it indicates that distance measurement is not possible, and when only the direction to the in-focus can be used, the display content is only "direction". . If both the distance to the in-focus position and the direction can be used, the display content is determined according to the amount of change in the position of the focus detection area as described in FIG. Here, in the case of “no movement” and “small movement”, “angle” if the number of times it is determined that the distance to the in-focus position can be used out of the average number of focus detection results, Display of (and "direction") may be performed. In this case, if the number of times it is determined that the distance to the in-focus position can be used is less than the predetermined number, it may be displayed only in the “direction”.

  This is because when a subject such as a face is detected, there is almost no change in distance in the face, and therefore the accuracy of focus detection is improved by using focus detection results from a plurality of focus detection areas in the face frame. It is because

  In the case of a subject such as a person, it is expected to move around in the screen. Therefore, if the display method is the same as in the case of moving the focus detection area manually, it is likely that the movement amount of the focus detection area is determined to be "large movement" and the angle display can not be displayed, which is a disadvantage for the user. Therefore, in the focus assist display at the time of object detection, angle display and direction display are performed using focus detection results of a plurality of focus detection areas arranged in the object detection frame. This makes it possible to achieve both stable angle display by using a plurality of focus detection results and responsiveness by not performing averaging processing.

  Further, in the case of a person, the accuracy of focus assist display can be further improved by changing the focus detection area to be used according to the angle of the face of the subject.

Display Control of Focus Assist Next, focus assist display control of the present embodiment in the camera body 20 will be described. FIG. 5 is a flowchart showing a procedure of main processing of focus assist display control performed by the camera control unit 207. This process is executed in a predetermined cycle according to a computer program stored in the camera control unit 207. For example, it may be executed at a readout cycle (every vertical synchronization period) of an imaging signal from the imaging device 201 for generating an image for one frame (or one field), or may be repeated a plurality of times within the vertical synchronization period. You may

  First, in step S101, the camera control unit 207 determines whether a manual focus operation is possible. If the manual focus operation is possible, the process proceeds to step S102. If not, the process ends. In S102, the camera control unit 207 performs setting processing of the focus detection area.

  Here, the setting process of the focus detection area performed in S102 will be described using FIGS. 6 and 7.

  FIG. 6 is a diagram showing an example of the focus detection area. FIG. 6A is a view showing the focus detection area 402 set on the pixel array 401 (light receiving area) constituting the imaging device 201. As shown in FIG. The calculation area 404 for reading out the focus signal necessary for performing the correlation calculation described later is an area in which the focus detection area 402 and the shift area 403 necessary for the correlation calculation are combined. In FIG. 6A, p, q, s, and t respectively indicate coordinates in the x-axis direction, the calculation area 404 is in the range of p to q, and the focus detection area 402 is in the range of s to t.

  FIG. 6B shows the case where the focus detection area 402 is divided into five focus detection areas 405 to 409. As an example, in this embodiment, the focus shift amount is calculated for each of the focus detection areas 405 to 409 to perform focus detection. Then, the most reliable focus detection result is selected from the focus detection results obtained for each of the plurality of focus detection areas 405 to 409, and the defocus amount calculated from the focus detection result is used for focus assist display. The number of focus detection areas is not limited to five.

  FIG. 6C is a view showing a temporary focus detection area 410 in which the focus detection areas 405 to 409 of FIG. 6B are connected. As an example of the embodiment, the defocus amount calculated from the focusing signal obtained from the area in which the plurality of focus detection areas are connected as described above may be used for the focus assist display.

  Further, in the case of a camera in which the subject detection function is effective, as shown in FIG. 6D, it is possible to set the focus detection area 419 at the position of the detected face 420. In this case, one or a plurality of focus detection areas 419 are set for the detected face 420, and one effective defocus amount and an effective defocus direction are calculated from the focus detection result obtained from the set focus detection areas. Do. Then, the effective defocus amount and / or the effective defocus direction are used for focus assist display.

  In addition, in an imaging apparatus having a function such as touch input, it is possible to freely set the focus detection area by designation of the user. As shown in FIG. 6E, the focus detection area can be set at the designated position 421.

  FIG. 7 is a flowchart showing an example of setting processing of the focus detection area. First, in S201, the camera control unit 207 determines whether the position of the focus detection area is designated. If the position of the focus detection area is designated, the process proceeds to step S205. If not, the process proceeds to step S202. The specification method is different from the subject matter of the present invention, and thus details thereof will be omitted. However, for example, the user can specify by a touch panel (not shown) or the cross key operation. In step S205, as illustrated in FIG. 6E, the camera control unit 207 sets the focus detection area at the designated position.

  In step S202, the camera control unit 207 determines whether the subject detection function (here, the face detection function) is on or off. If the subject detection function is ON, the process proceeds to step S204. If not, the process proceeds to step S203. In S203, the face is not detected, and the position of the focus detection area is not designated, so the camera control unit 207 sets the focus detection area at a predetermined position (for example, the center). In S204, as shown in FIG. 6D, the camera control unit 207 sets a focus detection area at the position of the detected face. If no face is detected, the focus detection area may be set at a predetermined position, as in S203.

  Note that the arrangement of the focus detection area, the size of the area, and the like are not limited to the examples shown in FIGS. 6 and 7, and can be set without departing from the scope of the invention.

  As described above, when the setting of the focus detection area in S102 is completed, the process proceeds to S103. In step S103, the camera control unit 207 determines whether the focus detection area is set to the position of the face detected by the subject detection unit 210. If the position of the face is set, the process proceeds to step S112. If not, the process proceeds to step S104.

  In S104, focus detection processing is performed. Here, the focus detection process performed in S104 will be described using FIGS.

  FIG. 8 is a flowchart showing focus detection processing, which is performed by the focus signal processing unit 204. First, in S301, the focus signal processing unit 204 acquires a pair of focusing signals from the focus detection area set in S102. Next, in S302, the focus signal processing unit 204 calculates a correlation amount from the pair of focusing signals acquired in S301. Subsequently, in S303, the focus signal processing unit 204 calculates a correlation change amount from the correlation amount calculated in S302. Then, in S304, the focus signal processing unit 204 calculates the out-of-focus amount from the correlation change amount calculated in S303. In step S305, the focus signal processing unit 204 calculates the reliability of the focusing signal acquired in step S301. This degree of reliability corresponds to the degree of reliability which indicates how reliable the defocus amount calculated in S304 is. These processes are performed as many as the number of focus detection areas set. Then, in S306, the focus signal processing unit 204 converts the defocus amount into the defocus amount for each focus detection area.

  The defocus amount may be expressed by an absolute distance from the in-focus position or the number of pulses necessary to move the focus lens 103 to the in-focus position, and such an expression different from such an expression in terms of dimension and unit Or, it may be a relative expression. That is, it may be any value as long as it can be determined how far away from the in-focus state it can be determined, and it can be determined that it can shift to the in-focus state if it is focus controlled.

  The focus detection process described with reference to FIG. 8 will be described in detail with reference to FIGS. 9 and 10. FIG. 9 is a view showing an example of the focus signal acquired from the focus detection area set in S102, where five focus detection areas 405 to 409 are set as shown in FIG. 6 (b). Case is shown. s to t correspond to the focus detection area, and p to q correspond to the calculation area 404 required for the correlation amount calculation based on the shift amount. Also, x to y represent one focus detection area. A solid line 501 represents an A image signal, and a broken line 502 represents a B image signal.

  FIG. 9A is a diagram representing the A image signal 501 and the B image signal 502 before shifting by waveforms. FIG. 9 (b) is a diagram shifted in the positive direction with respect to the waveforms of the A image signal 501 and the B image signal 502 before the shift shown in FIG. 9 (a), and FIG. The image is shifted in the negative direction with respect to the waveforms of the A image signal 501 and the B image signal 502 before the shift shown in FIG. When calculating the amount of correlation, the A image signal 501 and the B image signal 502 are shifted by one bit in the direction of the arrows.

  Subsequently, a method of calculating the correlation amount COR in S302 will be described. First, as described in FIGS. 9B and 9C, the A image signal 501 and the B image signal 502 are shifted by 1 bit each, and the A image signal 501 and the B image signal 502 in each shift state are shifted. The sum of the absolute values of the differences is calculated for each of the focus detection areas 405 to 409. Here, the minimum shift number is p−s and the maximum shift number is q−t. Further, assuming that the shift amount is i, x is a start coordinate of the focus detection area, and y is an end coordinate of the focus detection area, the correlation amount COR can be calculated by the following equation (1).

  FIG. 10A is a diagram showing an example of changes in the amount of correlation, in which the horizontal axis of the graph indicates the amount of shift and the vertical axis indicates the amount of correlation. In the correlation amount waveform 601, 602 and 603 indicate around the extreme value. Among them, the smaller the correlation amount, the higher the degree of coincidence between the A image signal 501 and the B image signal 502.

Subsequently, a method of calculating the correlation change amount ΔCOR in S303 will be described. First, from the correlation amount waveform shown in FIG. 10A, the correlation change amount is calculated from the difference between the correlation amounts of one shift skipping. At this time, the minimum shift number is p−s in FIG. 9 and the maximum shift number is q−t in FIG. When the shift amount is represented by i, the correlation change amount ΔCOR can be calculated by the following equation (2).
ΔCOR [i] = ΔCOR [i−1] −ΔCOR [i + 1]
(P−s + 1) <i <(q−t−1) (2)

  FIG. 10B is a diagram showing an example of the correlation change amount ΔCOR. The horizontal axis of the graph indicates the shift amount, and the vertical axis indicates the correlation change amount. In the correlation change amount waveform 604, reference numerals 605 and 606 denote areas where the correlation change amount changes from plus to minus. The state in which the amount of change in correlation becomes zero in 605 and 606 is called zero cross, the degree of coincidence between the A image signal 501 and the B image signal 502 is the highest, and the defocus amount is obtained based on the shift amount at that time.

  FIG. 11A is an enlarged view of a portion 605 of FIG. 10B, and 607 is a part of the correlation change amount waveform 604. A method of calculating the focus deviation amount PRD in S304 will be described with reference to FIG. First, the defocus amount PRD is divided into an integral part β and a fractional part α. The fractional part α can be calculated by the following equation (3) from the similarity relationship between the triangle ABC and the triangle ADE in FIG. 11 (a).

一方、整数部分βは、図１１（ａ）より、以下の式（４）によって算出することができる。
β＝ｋ−１ …（４）
以上のようにして得られたαとβの和から、ピントずれ量ＰＲＤを算出することができる。

On the other hand, the integer part β can be calculated by the following equation (4) from FIG. 11 (a).
β = k−1 (4)
The focus shift amount PRD can be calculated from the sum of α and β obtained as described above.

When there are a plurality of zero crossings as shown in FIG. 10 (b), the place where the steepness maxder (hereinafter referred to as "steepness") of the correlation amount change at the zero crossings is large is taken as the first zero crossing. . The steepness is an index indicating the ease of specifying the in-focus position, and indicates that the larger the value, the easier it is to specify the in-focus position. The steepness can be calculated by the following equation (5).
maxder = | ΔCOR [k−1] | + | ΔCOR [k] | (5)

  As described above, when there are a plurality of zero crossings, the first zero crossing is determined by the steepness at the zero crossing.

  Subsequently, a method of calculating the reliability of the image signal (focusing signal) in S305 will be described. The reliability can be defined by the above-described sharpness and the coincidence fnclvl between the A and B image signals (hereinafter referred to as "two-image coincidence"). The degree of image coincidence is an index that represents the accuracy of the amount of focus shift, and the smaller the value, the better the accuracy.

FIG. 11B is an enlarged view of a portion near the polar region 602 in FIG. 10A, and 608 is a part of the correlation amount waveform 601. The degree of image coincidence can be calculated by the following equation (6).
(i) When ΔCOR [k−1] × 2 ≦ maxder
fnclvl = COR [k-1] + ΔCOR [k-1] / 4
(ii) When ΔCOR [k-1] × 2> maxder
fnclvl = COR [k] -ΔCOR [k] / 4 (6)

  When the focus detection process ends as described above in S104, the process proceeds to S105. In S105, the camera control unit 207 determines the movement amount of the focus detection area. As described above with reference to FIG. 4, the determination of the movement amount is made based on the overlapping rate of the focus detection area between the previous detection of the focus state and the current detection of the focus state. If the duplication rate is 100 to 80%, it is determined that "no movement", if the duplication rate is 80 to 50%, "small movement", and if the duplication rate is 50 to 0%, "high movement". If the movement is large, the process proceeds to step S106. If the movement is small, the process proceeds to step S107. If the movement is small, the process proceeds to step S108. The method of determining the movement amount is not limited to the above-described method, and may be determined based on, for example, a change in coordinates of the center position of the focus detection area between the previous detection time and the current focus detection time.

  In S106, S107, and S108, the camera control unit 207 obtains an average of the focus detection results. Processing is performed using the average number of times as a parameter. Here, the focus detection result averaging process performed in S106, S107, and S108 of FIG. 5 will be described with reference to FIG.

  In step S401, the camera control unit 207 acquires the average number of times Th_A described in FIG. 4 and transitions to step S402. In step S402, the camera control unit 207 determines whether the average number of times Th_A is zero. If the average number Th_A is 0, the process proceeds to step S403. In S403, the averaging process is not performed, and the current focus detection result (the defocus amount and the reliability) is set as data used for focus assist display.

  On the other hand, if not 0, the process proceeds to step S404, and the camera control unit 207 calculates the average of the defocus amounts by dividing the sum of the defocus amounts obtained by the most recent Th_A focus detections by Th_A. . Subsequently, in S405, the camera control unit 207 calculates the average of the reliability by dividing the sum of the reliability obtained by the most recent Th_A times of focus detection by Th_A.

  In step S406, the camera control unit 207 sets the average of the focus detection results (defocus amount and reliability) obtained in steps S404 and S405 as data used for focus assist display. When the focus detection result averaging process is completed as described above, the process returns to the process of FIG.

  After the processing in S107 and S108, in S109, the camera control unit 207 performs calculation processing of an angle index indicating the display position of the angle display part used for the focus assist display. In addition, when the movement amount is determined to be “moving large” in S105, the angle display part is not displayed as described with reference to FIG. 4, so after the processing in S106, the angle index is not calculated. It progresses to S110.

  Here, the angle index calculation process performed in S109 will be described using FIG. In step S501, the camera control unit 207 determines whether the average of the degrees of reliability calculated in step S107 or S108 is equal to or greater than a predetermined threshold Th_B. This determination is performed to determine whether the angle index may be calculated using the average of the defocus amounts calculated in step S107 or S108. If the degree of reliability is equal to or higher than the threshold Th_B, it is determined that the defocus amount is a reliable value, and the process transitions to S502. If it is smaller than the threshold Th_B, it is determined that the defocus amount may not be reliable, and the process transitions to S504.

  In step S502, the camera control unit 207 converts the defocus amount into an angle. As an example of conversion, the depth of focus is 1 °, and the angle index is calculated by calculating how many times the defocus amount is the depth of focus. Note that the conversion method to the angle is not limited to this calculation method, such as changing according to the sensitivity of the focus ring or the like.

  In S503, the camera control unit 207 sets a flag indicating that the angle display part is to be displayed, and in S504, the camera control unit 207 sets a flag indicating that the angle display part is not to be displayed, It progresses to S110 of FIG.

  In S110, the camera control unit 207 performs calculation processing of a direction index indicating the display direction of the direction display part used for focus assist display. Here, the direction index calculation process performed in S110 will be described using FIG. In S601, the camera control unit 207 determines whether the reliability obtained in S106, S107 or S108 is equal to or greater than a predetermined threshold Th_C. This determination is performed to determine whether or not the direction indicator may be calculated using the defocus amount calculated in S106, S107 or S108. If the reliability is equal to or higher than the threshold Th_C, it is determined that the direction calculated from the defocus amount is a reliable value, and the process transitions to S602. If smaller than the threshold Th_C, it is determined that the direction calculated from the defocus amount may be unreliable, and the process transitions to S604. The threshold Th_B is a threshold indicating a higher degree of reliability than the threshold Th_C.

  In step S602, the camera control unit 207 converts the defocus amount into a direction. As an example, the direction is calculated from the sign of the defocus amount. In step S603, the camera control unit 207 sets a flag indicating that direction display is to be performed, and in step S604, sets a flag indicating that direction display is not performed, and the process proceeds to step S111 in FIG.

  In S111, the camera control unit 207 performs focus assist display processing. In this process, the display of parts necessary for the focus assist display described with reference to FIG. 3, the focus state, and the focus detection can not be performed based on the flag of the angle display and the direction display, and the calculated angle index and direction index. Is displayed on the display unit 205.

  On the other hand, when the focus detection area is set at the position of the face detected by the subject detection unit 210 in S103, the process proceeds to S112, and the camera control unit 207 determines the direction of the face. If it is determined that the face direction is a side face, the process proceeds to step S113. If it is determined that the face direction is the front direction or the backward direction, the process proceeds to step S114.

  In S113 and S114, the camera control unit 207 sets an additional focus detection area. Here, as shown in FIG. 15, the focus detection area to be used is additionally set in accordance with the direction of the face. FIG. 15A is a view for explaining a setting method of the focus detection area in the case of the front face. Focus detection areas 702, 703, and 704 are set for the front face 701. In the case of the frontal face, for example, if the focus detection area 702 is set in S102, the focus detection areas 703 and 704 are additionally set in the horizontal direction. Here, by additionally setting the focus detection area within the same face area as the focus detection area 702 set in S102, the focus detection area 703 and the focus detection areas 703 and 704 to be additionally set become substantially the same distance. . Thus, a plurality of focus detection areas are arranged horizontally, and focus assist display is performed using a plurality of focus detection results.

  On the other hand, FIG. 15 (b) is a diagram for explaining the setting method of the focus detection area in the case of horizontal orientation. Focus detection areas 706, 707, and 708 are set for the profile 705. In the case of horizontal orientation, for example, assuming that the focus detection area 707 is set in S102, the focus detection areas 706 and 708 are additionally set in the vertical direction. Here, by additionally setting the focus detection area within the same face area as the focus detection area 707 set in S102, the focus detection areas 706 and 708 to be additionally set are approximately the same distance as the focus detection area 707. . When the face is in the horizontal orientation, if the focus detection area is arranged in the horizontal direction, the focus detection area is arranged in the vertical direction since it is likely to be out of the face area. Thus, a plurality of focus detection areas are arranged in the vertical direction, and focus assist display is performed using a plurality of focus detection results. Although three focus detection areas are provided in this embodiment, this is an example, and the number of focus detection areas is not limited to this example.

  In S115, focus detection processing is performed on each of the plurality of focus detection areas as described above with reference to FIGS. S116 is a calculation process based on the plurality of focus detection results obtained in S115. Specifically, the camera control unit 207 averages the plurality of focus detection results calculated in S115. Although the average is used in the present embodiment, it is also possible to select the focus detection result to be used in consideration of the reliability of the focus detection result and the like.

  After processing of the focus detection result, the above-described processing is performed in S109 and S110, and the camera control unit 207 performs focus assist display processing in S111.

  As described above, according to the present embodiment, in the focus assist display at the time of manual focus adjustment, the responsiveness can be improved while maintaining the stability of the focus state display. In the present embodiment, the configuration for performing the focus assist display on the display unit 205 provided in the camera body 20 has been described. However, in a display unit different from the camera body 20, focus is obtained using information acquired from the camera body 20. An assist display may be performed.

  In addition, the present invention supplies a program that implements one or more functions of the above-described embodiments to a system or apparatus via a network or storage medium, and one or more processors in a computer of the system or apparatus execute the program. It can also be realized by a process of reading out and executing. It can also be implemented by a circuit (eg, an ASIC) that implements one or more functions.

  Although the present invention has been described in detail based on its preferred embodiments, the present invention is not limited to these specific embodiments, and various forms within the scope of the present invention are also included in the present invention. Be

  103: focus lens, 105: focus lens drive unit, 106: lens control unit, 107: lens operation unit, 201: imaging device, 203: camera signal processing unit, 204: focus signal processing unit, 205: display unit, 207: Camera control unit, 210: subject detection unit, 211, 212: photodiode, 301: focus detection area, 302: angle display part, 303: focusing position display part, 304: circular part, 305 direction display part

Claims (17)

A display control apparatus for displaying on a display means an image based on a signal generated by an imaging means for receiving and photoelectrically converting a light flux incident through an imaging optical system,
Focus detection means for repeatedly detecting a focus state on the basis of a pair of image signals output from a focus detection area set in a light receiving area of the imaging means;
Display control means for superimposing an index based on the focus state detected by the focus detection means on the image and displaying it on the display means;
Specifying means for receiving an operation for specifying the position of the focus detection area;
Have
The display control means changes the responsiveness of the display of the indicator to the detection result of the focus state by the focus detection means in accordance with the amount of change of the position of the focus detection area specified via the specification means. A display control device characterized by The display control according to claim 1, wherein the display control means changes an item displayed by the index in accordance with a change amount of a position of the focus detection area specified through the specification means. apparatus. The focus state includes the defocus amount and the direction to the in-focus position,
As the indication form of the index, a first indication form indicating the defocus amount and the direction to the in-focus position, and a second indication indicating the direction to the in-focus position without indicating the defocus amount With form
The display control means switches the first display form and the second display form on the basis of the amount of change in position of the focus detection area designated through the designation means. The display control device according to 1 or 2 . The display control means displays the index in the second display mode when the amount of change in the position of the focus detection area designated through the designation means is larger than the first amount, and the amount of change is The display control device according to claim 3 , wherein the index is displayed in the first display mode when the first amount is smaller than or equal to the first amount. When displaying the index in the second display mode, the display control means indicates the direction to the in-focus position based on the focus detection area after the position is changed by the operation through the specifying means. The display control device according to claim 3 or 4 , wherein display is performed. When displaying the indicator in the first display mode, the display control unit displays the indicator based on an average of results of the focus detection unit detecting the focus state a plurality of times. The display control apparatus according to any one of claims 3 to 5 . When the index is displayed in the first display mode, the display control means may change the amount of change in the position of the focus detection area specified via the specifying means, if the amount of change in the position is larger than a second amount. 7. The display control device according to claim 6 , wherein the number of times of averaging the focus state is reduced as compared with the case where the amount is 2 or less. When it is determined that the defocus amount can be used based on the reliability of the image signal, the display control means responds to the amount of change in the position of the focus detection area designated via the designation means. The display control apparatus according to any one of claims 3 to 7 , wherein display of the index is changed. It further comprises subject detection means for detecting a predetermined subject from the image,
A first mode for receiving specification of the position of the focus detection area via the specification means, and a second mode for setting the focus detection area based on the position of the predetermined subject detected by the subject detection means The display control device according to any one of claims 1 to 8 , characterized in that 10. The display control method according to claim 9 , wherein the display control means changes the display of the index in the first mode in accordance with the amount of change in the position of the focus detection area specified via the specification means. The display control device according to. The subject when the predetermined subject is detected by the detection means, the display control device according to claim 9 or 10, wherein the second mode is set. The display control device according to any one of claims 9 to 11 , wherein, in the case of the second mode, a plurality of focus detection areas are set in the area of the predetermined subject. The predetermined subject is a face of a person, and the subject detection means further detects the direction of the face,
When the face orientation is front or back, the plurality of focus detection areas are arranged horizontally, and when the face is oriented horizontally, the plurality of focus detection areas are vertically oriented. The display control device according to claim 12 , wherein the display control device is arranged. The display control device according to any one of claims 1 to 13 .
And the imaging means,
The imaging unit has a plurality of pixels provided with a plurality of photoelectric conversion units for one microlens, and photoelectric conversion of a light flux incident through the photographing optical system is performed by the plurality of photoelectric conversion units to perform a pair of An image pickup apparatus characterized by outputting an image signal. A control method of a display control apparatus, which displays an image based on a signal generated by an imaging unit that receives a light flux incident through a photographing optical system and performs photoelectric conversion,
A focus detection step of repeatedly detecting a focus state on the basis of a pair of image signals output from a focus detection area set in a light receiving area of the imaging unit;
A display control step of superimposing an index based on the focus state detected in the focus detection step on the image and displaying it on a display unit;
Receiving an operation of specifying the position of the focus detection area via a specification unit;
In the display control step, the responsiveness of the display of the indicator to the detection result of the focus state by the focus detection step is changed according to the amount of change of the position of the focus detection area designated through the designation unit. Control method characterized by The program for making a computer perform each process of the control method of Claim 15 . A computer readable storage medium storing the program according to claim 16 .

Images