JP2016033576A - Imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To select a subject that is detected by subject characteristic detection means even when distance information is not obtained from a lens barrel and the like.SOLUTION: An imaging device comprises: focus detection information generation means 100 that generates focus information of an imaging optical system; subject characteristic detection means 103 that detects characteristic information on a subject; focus detection information extraction means 101 that extracts amounts of defocus at the closest distance and at the most distant distance from focus detection information to be obtained by the focus detection information generation means, and an amount of defocus of a location obtained by the subject characteristic detection means; and focus detection selection means 102 that selects one focus detection information in accordance with a prescribed threshold from focus detection information extracted by the focus detection information extraction means.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an imaging apparatus, and more particularly to selection of a focus detection result.

  2. Description of the Related Art Conventionally, there is known an imaging apparatus that detects a subject candidate from an image captured by an imaging unit, obtains an image magnification of the subject candidate, and selects the subject candidate based on the result. Patent Document 1 discloses an imaging apparatus that corrects an image magnification based on a focus detection result and selects an object to be photographed.

JP 2009-198951 A

  However, in the prior art disclosed in the above-mentioned patent document, since the distance information obtained from the lens drive control device is used, if the distance information cannot be obtained from the lens barrel, the image magnification may include an error, There is a problem that it is difficult to select subject candidates.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an imaging apparatus capable of selecting an appropriate subject even when distance information cannot be obtained from a lens barrel or the like.

  In order to achieve the above object, the present invention provides a focus detection information generation unit that detects a focus state in an imaging optical system and generates focus detection information, a subject feature detection unit that detects subject feature information, and the focus Focus detection information extraction means for extracting focus detection information from a plurality of focus detection information generated by the detection information generation means, and one focus detection information from the focus detection information extracted by the focus detection information extraction means The focus detection information extracting means selects the first focus detection information closest to the image pickup apparatus and the second of the position notified by the subject feature detection means. Focus detection information and third focus detection information farthest from the imaging device are extracted, and the focus detection information selection means extracts the focus detection information extracted by the focus detection information extraction means. And selects one of the detected information.

  According to the present invention, even when distance information cannot be obtained from a lens barrel or the like, the subject detected by the subject feature detection means can be selected.

It is a block diagram which shows the concept of Example 1 of this invention. 1 is a block diagram illustrating a configuration of a digital single-lens reflex camera including Example 1. FIG. 3 is a flowchart illustrating a photographing process in Embodiment 1. 3 is a flowchart illustrating details of photometry / focus detection processing in Embodiment 1. It is the figure which showed the relationship between a to-be-photographed object and a defocus amount. It is the figure which showed the relationship between a photometry area | region and a focus detection point. 12 is a flowchart illustrating details of photometry / focus detection processing in the second embodiment.

  The mode for carrying out the invention is as described in Example 1 below.

  FIG. 1 is a block diagram showing the concept of Embodiment 1 of the imaging apparatus of the present invention. Reference numeral 100 denotes focus detection information generating means for detecting defocus amounts of a plurality of coordinates in the photographing screen. Reference numeral 103 denotes subject feature detection means for detecting a characteristic portion (for example, a skin color region) from the subject image.

  Reference numeral 101 denotes a focus detection information extraction unit, and a defocus amount closest to the imaging device, a defocus amount farthest from the imaging device, and a feature portion detected by the subject feature detection unit 103 from the focus detection information generation unit 100 Among them, it is a means for extracting three defocus amounts that are closest to the imaging device.

  Reference numeral 102 denotes focus detection information selection means. It is means for selecting focus detection information according to a predetermined threshold from the three defocus amounts extracted by the focus detection information extraction means.

  Next, a digital single-lens reflex camera that is Embodiment 1 of the imaging apparatus of the present invention will be described. FIG. 2 is a block diagram showing the configuration of the digital single-lens reflex camera.

  Reference numeral 201 denotes a photographing lens. Reference numeral 202 denotes a lens driving circuit. The lens driving circuit 202 is configured by, for example, a DC motor or a stepping motor, and adjusts the focus by changing the focus lens position of the photographing lens 201 under the control of the microcomputer 224.

  Reference numeral 203 denotes a zoom drive circuit. The zoom drive circuit 203 is constituted by, for example, a DC motor or a stepping motor, and changes the focal length of the photographic lens 201 by changing the zoom lens position of the photographic lens 201 under the control of the microcomputer 224.

  Reference numeral 204 denotes an aperture. Reference numeral 205 denotes an aperture driving circuit. A diaphragm driving circuit 205 drives the diaphragm 204. The amount to be driven is calculated by the microcomputer 224, and the optical aperture value is changed.

  Reference numeral 206 denotes a main mirror for switching the light beam incident from the photographing lens 201 between the viewfinder side and the image sensor side. The main mirror 206 is always arranged so as to reflect the light beam to the viewfinder, but when photographing is performed, the main mirror 206 jumps upward so as to guide the light beam to the image pickup device 112 and evacuates from the light beam. . The main mirror 206 is a half mirror so that the central part can transmit part of the light, and part of the light beam is transmitted so as to enter the focus detection sensor for focus detection.

  Reference numeral 207 denotes a sub-mirror for reflecting a light beam transmitted from the main mirror 206 to a focus detection sensor (disposed in the focus detection circuit 210) for performing focus detection. Reference numeral 208 denotes a pentaprism that forms a viewfinder. In addition, the viewfinder is composed of a focus plate, an eyepiece lens (not shown), and the like.

  Reference numeral 209 denotes a photometric circuit. The color and brightness of the subject image formed on a focus plate (not shown) are converted into an electrical signal by a photometric sensor (located in the photometric circuit 209) provided with a color filter.

  Reference numeral 210 denotes a focus detection circuit. The light beam transmitted through the center of the mirror 206 and reflected by the sub-mirror 207 reaches a focus detection sensor for performing photoelectric conversion disposed inside the focus detection circuit 210. The defocus amount that is a result of focus detection is obtained by calculating the output of the focus detection sensor. The microcomputer 224 evaluates the calculation result and instructs the lens driving circuit 202 to drive the focus lens.

  Reference numeral 211 denotes a focal plane shutter. A shutter drive circuit 212 drives the focal plane shutter 211. The shutter opening time is controlled by the microcomputer 224.

  Reference numeral 213 denotes an image sensor. As the image sensor 213, a CCD, a CMOS sensor, or the like is used, and the subject image formed by the photographing lens 101 is converted into an electric signal.

  Reference numeral 214 denotes a clamp circuit. Reference numeral 215 denotes an AGC circuit. The clamp circuit 214 and the AGC circuit 215 perform basic analog signal processing before A / D conversion, and the microcomputer 224 changes the clamp level and the AGC reference level.

  Reference numeral 216 denotes an A / D converter. The A / D converter 216 converts the analog output signal of the image sensor 213 into a digital signal. Reference numeral 217 denotes a video signal processing circuit, which is realized by a logic device such as a gate array. Reference numeral 220 denotes a memory controller. Reference numeral 221 denotes a memory. An external interface 222 can be connected to a computer or the like. Reference numeral 223 denotes a buffer memory.

  The video signal processing circuit 217 performs filter processing, color conversion processing, and gamma processing on the digitized image data, performs compression processing such as JPEG, and outputs the result to the memory controller 220.

  The video signal processing circuit 217 can output information such as exposure information and white balance of the signal from the image sensor 213 to the microcomputer 224 as necessary. Based on the information, the microcomputer 224 instructs white balance and gain adjustment. In the case of the continuous shooting operation, the shooting data is temporarily stored in the buffer memory 223 as an unprocessed image, the unprocessed image data is read out through the memory controller 220, and image processing or compression processing is performed by the video signal processing circuit 217. Perform continuous shooting. The number of continuous shots depends on the size of the buffer memory.

  In the memory controller 220, unprocessed digital image data input from the video signal processing circuit 217 is stored in the buffer memory, and processed digital image data is stored in the memory 221. Conversely, the image data is output from the buffer memory 223 or the memory 221 to the video signal processing circuit unit 217. The memory 221 may be removable. The memory controller 220 can output an image stored in the memory 221 via an external interface 222 that can be connected to a computer or the like.

  Reference numeral 224 denotes a microcomputer. Reference numeral 225 denotes an operation member. The operation member 225 transmits the state to the microcomputer 224, and the microcomputer 224 controls each part according to the change of the operation member.

  Reference numeral 226 denotes a switch 1 (hereinafter referred to as SW1). Reference numeral 227 denotes a switch 2 (hereinafter referred to as SW2). SW <b> 1 and SW <b> 2 are switches that are turned on and off by operating the release button, and are each one of the input switches of the operation member 225. When only SW1 is on, the release button is half-pressed, and in this state, autofocus operation and photometry operation are performed.

  When both SW1 and SW2 are on, the release button is fully pressed, and the release button for recording an image is on. Shooting is performed in this state. Further, a continuous shooting operation is performed while SW1 and SW2 are kept on. In addition, switches such as an ISO setting button, an image size setting button, an image quality setting button, and an information display button are connected to the operation member 225, and the switch state is detected.

  Reference numeral 228 denotes a liquid crystal driving circuit. Reference numeral 229 denotes an external liquid crystal display member. Reference numeral 230 denotes a liquid crystal display member in the viewfinder. The liquid crystal driving circuit 228 drives the external liquid crystal display member 229 and the in-finder liquid crystal display member 230 in accordance with the display content command of the microcomputer 224. The in-viewfinder liquid crystal display member 230 is provided with a backlight such as an LED (not shown), and the LED is also driven by the liquid crystal driving circuit 228.

  The microcomputer 224 confirms the memory capacity through the memory controller 220 based on the predicted image size data corresponding to the ISO sensitivity, the image size, and the image quality set before shooting, and then the remaining number of images that can be shot. Can be calculated. If necessary, it can also be displayed on the external liquid crystal display member 229 and the liquid crystal display member 230 in the viewfinder.

  Reference numeral 231 denotes a non-volatile memory (EEPROM) that can store data even when the camera is not turned on. Reference numeral 232 denotes a power supply unit. The power supply unit 232 supplies power necessary for each IC and drive system.

  Next, an example of the relationship between the photometry area and the focus detection point according to the first embodiment of the present invention will be described with reference to FIG. The photometric area 601 is composed of a total of 25 areas of 5 vertical areas and 5 horizontal areas. In the photometry process, photometry results and color information are calculated according to this block. The focus detection point 602 is composed of 13 points. In the focus detection process, the defocus amount of the focus detection point 602 is calculated, and one of the focus detection points 602 is selected. In this embodiment, the focus detection point 602 is positioned at the center of the photometric area 601.

  Next, an example of the operation using the color information of the photometric sensor will be described with reference to the flowchart of FIG. When SW1 is turned on in step S301, photometric / focus detection processing in step S302 is performed. When the photometry / focus detection process ends, it is determined in step S303 whether focus detection has been completed.

  If focus detection cannot be performed, the process proceeds to step S307, a predetermined lens drive (search drive) for searching for a focus detectable state is performed, and the process returns to step S302. On the other hand, if focus detection has been performed, the process proceeds to step S304 to determine whether the focus detection result is within the in-focus range. If it is determined in step S304 that it is not within the focusing range, the process proceeds to step S308, the lens is driven based on the defocus amount notified as the focus detection result, and the process returns to step S302.

  On the other hand, if it is within the in-focus range, the process proceeds to step S305, and it is determined whether SW2 is turned on. If it is determined in step S305 that SW2 is on, shooting is performed, and a series of shooting processing is exited. If it is determined in step S305 that SW2 is not turned on, the process advances to step S309 to determine whether SW1 is turned on. If it is determined in step S309 that SW1 is turned on, the process returns to step S302. If it is determined in step S309 that SW1 is not turned on, the series of shooting processing ends.

  Next, an example of the operation of the photometry / focus detection process in step S302 will be described based on the flowchart of FIG. It is assumed that the relationship between the camera and the subject is as shown in FIG. In FIG. 5, it is assumed that the main subject 502 is in a photometric area 601 and a focus detection point 602 that are determined as, for example, a skin color in step S407 described later. The closest subject 501 represents the focus detection result closest to the camera among the focus detection points 602. A far subject 503 represents a focus detection result farthest from the camera among the focus detection points 602.

  In step S401, accumulation of the photometric sensor and the focus detection sensor is started. In step S402, the process waits until the focus detection sensor completes accumulation. When the accumulation of the focus detection sensor is completed, it waits until the photometric sensor is accumulated in step S403. When accumulation of the photometric sensor is completed, defocus amount calculation is performed for all focus detection points 602 in step S404.

  In step S405, photometric values and color information are calculated for all photometric areas 601. The color information indicates whether the color of each photometric area acquired from the photometric sensor is determined as a skin color, for example. In this embodiment, it is assumed that the central photometric area 601 corresponding to the main subject 502 is determined as the skin color.

  In step S406, whether the defocus amount obtained in step S404 is valid is determined by obtaining reliability from the output result of the focus detection sensor. If it is determined in step S406 that the defocus amount is not valid, the process proceeds to step S410, and the process of step S302 in FIG. If it is determined in step S406 that the defocus amount is valid, the process proceeds to step S407.

  In step S407, it is determined whether, for example, skin color is included in the color information of all the photometric areas 601 obtained in step S405. If it is determined in step S407 that the skin color is not included in any of the photometric areas 601 among the color information of all the photometric areas 601, the focus including the closest subject 501 is determined from the defocus amount obtained in step S404. The detection point 602 is selected, and the process of step S302 in FIG. 3 is exited. If it is determined that one or more skin colors are included in the photometric area 601, the process proceeds to step S408.

  In step S408, it is determined whether the defocus amount difference 531 is larger than the first threshold value. The defocus amount difference 531 represents the difference between the defocus amount 522 of the main subject 502 and the defocus amount 523 of the far subject 503. If the defocus amount difference 531 is larger than the first threshold value, it indicates that the distance from the camera of the main subject 502 is within the distance represented by the first threshold value. Therefore, it seems that the photographer is closer to the photographer's intention when it is determined that the photographer intends to photograph the main subject 502. Therefore, if the defocus amount difference 531 is larger than the first threshold value, the process proceeds to step S412 to select the focus detection point 602 including the main subject 502, and the process of step S302 in FIG.

  On the other hand, when the defocus amount difference 531 is equal to or smaller than the first threshold value, the following shooting composition state is conceivable. That is, when the main subject 502 is standing at the wall, in this case, the wall is determined to be the far subject 503, so the main subject 502 is judged to be in a position close to the far side, and the main subject 502 is not selected. Therefore, if the defocus amount difference 531 is equal to or smaller than the first threshold value, the process proceeds to step S409 in order to make a determination using the defocus amount difference 532. The defocus amount difference 532 is a difference between the defocus amount 521 and the defocus amount 522 of the closest subject 501.

  In step S409, it is determined whether the defocus amount difference 532 is larger than the second threshold value. When the defocus amount difference 532 is larger than the second threshold, it is considered that the close subject 501 and the main subject 502 have a distance. At this time, it is determined that the photographer is closer to the photographer's intention when it is determined that the photographer is shooting the close subject 501. Therefore, when the defocus amount difference 532 is larger than the second threshold value, the process proceeds to step S413, the focus detection point 602 including the closest subject 501 is selected, and the process of step S302 in FIG. When the defocus amount difference 532 is equal to or smaller than the second threshold value, it is considered that the close subject 501 and the main subject 502 are close to each other. Therefore, the focus detection point 602 including the main subject 502 is selected, and the steps in FIG. The process of S302 is exited.

  As described above, according to the first embodiment, the subject detected by the subject feature detection unit 103 can be selected even when the subject distance is calculated only by the defocus amount.

  In the second embodiment, a case where the main subject 502 extends over a plurality of photometric areas 601 and a plurality of focus detection points 602 will be described.

  A flowchart of the photographing process is shown in FIG. 3 and is the same as that of the first embodiment. Next, an example of the operation of the photometry / focus detection process in step S302 will be described based on the flowchart of FIG. Steps S701 to S714 are the same as S401 to S414 in FIG.

  In step S715, a main subject candidate is determined. In this embodiment, since the main subject 502 extends over a plurality of photometry areas 601, the plurality of photometry areas 601 are recognized as skin colors. In step S715, the focus detection point 602 determined to be closest to the camera is selected from the defocus amounts of the focus detection points 602 corresponding to the plurality of photometric areas 601 recognized as skin colors.

  When comparing the defocus amount difference 531 with the first threshold value in step S708, the defocus amount difference 531 is the difference between the defocus amount of the focus detection point 602 selected in step S715 and the defocus amount of the far object 503. Become.

  The defocus amount difference 532 used in step S709 is also the difference between the defocus amount of the focus detection point 602 selected in step S715 and the defocus amount of the closest subject 501.

  As described above, according to the second embodiment, the subject detected by the subject feature detection unit 103 can be used even when the main subject extends over a plurality of photometry areas and the subject distance is calculated only by the defocus amount. It becomes possible to select.

201 photographic lens, 202 lens driving circuit, 203 zoom driving circuit,
204 stop, 205 stop drive circuit, 206 primary mirror, 207 sub mirror,
208 penta prism, 209 photometry circuit, 210 focus detection circuit,
211 Focal plane shutter, 212 Shutter drive circuit,
213 Image sensor, 214 Clamp circuit, 215 AGC circuit,
216 A / D converter, 217 video signal processing circuit, 220 memory controller,
221 memory, 222 external interface, 223 buffer memory,
224 microcomputer, 225 operation member, 226 switch 1,
227 switch 2, 228 liquid crystal drive circuit, 229 external liquid crystal display member,
230 Liquid crystal display member in the viewfinder, 231 nonvolatile memory,
232 power supply unit, 600 shooting area, 601 photometry area,
602 Focus detection point

Claims (4)

  Focus detection information generation means (100) for detecting a focus state in the imaging optical system and generating focus detection information, subject feature detection means (103) for detecting feature information of the subject, and focus detection information generation means (100) Focus detection information extraction means (101) for extracting focus detection information from among the plurality of focus detection information generated by the above-mentioned (1), and one of the focus detection information extracted by the focus detection information extraction means (101). An imaging apparatus having focus detection information selection means (102) for selecting focus detection information, wherein the focus detection information extraction (101) means includes first focus detection information closest to the imaging apparatus, and subject feature detection. Extracting the second focus detection information at the position notified by the means (103) and the third focus detection information farthest from the imaging apparatus, and selecting the focus detection information selection means. 102), the imaging apparatus characterized by selecting one by the difference of said focus detection information focus detection information extraction unit (101) is extracted.   The focus detection information selection means (102) selects second focus detection information when the difference between the second focus detection information and the third focus detection information is greater than a first threshold, and the second focus detection information is selected. When the difference between the first focus detection information and the third focus detection information is less than or equal to a first threshold and the difference between the first focus detection information and the second focus detection information is greater than the second threshold, the first The imaging apparatus according to claim 1, wherein focus detection information is selected.   The imaging apparatus according to claim 1, wherein the feature information of the subject is color information.   In the second focus detection information, when there are a plurality of positions notified by the subject feature detection means (103), focus detection of a location corresponding to the position obtained by the focus detection information generation means (100) is performed. The imaging apparatus according to any one of claims 1 to 3, wherein focus detection information closest to the imaging apparatus is used from among the information.