JP4804210B2 - Imaging apparatus and control method thereof - Google Patents

Description

  The present invention relates to an imaging apparatus capable of performing focus detection by a phase difference detection method and focus detection by a contrast method based on the contrast of a subject image of a captured image obtained from the imaging means, a control method thereof, and a computer program.

  2. Description of the Related Art Conventionally, there are electronic cameras that have a function of automatically adjusting parameters relating to imaging, such as an auto focus (AF) function, an automatic exposure (AE: auto exposure) function, and an auto white balance function.

  In the AF function, focus adjustment is performed at the reference lens and distance. In focus adjustment, an error at a level that does not cause a problem in actual shooting is allowed.

  Regarding the focus adjustment in the AF function, since both the camera body and the lens unit include manufacturing errors, there is a problem that a focus error larger than an allowable amount occurs in autofocus when the camera body and the lens unit are combined. was there.

  Moreover, in order to prevent the accuracy from becoming a problem when the camera body and the lens unit are combined, it is only necessary to reduce the tolerance at the time of manufacture in both the camera and the lens unit. As a result, there arises a problem that the manufacturing cost increases.

  Regarding the AF function, for example, Patent Document 1 obtains autofocus data from an AF sensor module and an image sensor arranged at conjugate positions in a test mode, and stores relative shift data of autofocus data. In the normal mode, there has been proposed an electronic image pickup apparatus that drives the photographing lens based on the autofocus relative deviation data.

  Japanese Patent Application Laid-Open No. 2004-228561 drives an imaging lens based on an evaluation value corresponding to the contrast of a subject image after driving the imaging lens based on a phase difference detection signal from a phase difference AF detection unit. A digital still camera has been proposed.

  In addition, Patent Documents 3 and 4 propose an apparatus that performs focus shifting with the AF function. Patent Document 5 proposes an image pickup apparatus that picks up an image while moving a focus lens by a full stroke and a unit amount, and uses an image with a maximum focus evaluation value based on a high-frequency component of a luminance signal as the best image. .

JP 2000-292684 A JP 2001-281530 A Japanese Patent No. 2757379 Japanese Patent Laid-Open No. 11-258488 Japanese Patent Application Laid-Open No. 11-211974 JP 2004-309866 A JP-A-9-197474

  By the way, Patent Document 6 includes a passive focus detection unit and a contrast focus detection unit. The contrast focus detection unit is operated according to the reliability of the position of the passive focusing lens detected by the passive focus detection unit, and the contrast. There has been proposed an automatic focus adjustment device that changes the moving range of the focus adjustment lens for detecting the lens.

  However, in the automatic focus adjustment apparatus described in Patent Document 6, only the reliability of the result of the passive focus detection unit is evaluated, and the reliability of the result of the contrast focus detection unit is not evaluated. .

  The present invention has been made in view of the above points, and realizes a highly accurate AF function by determining the reliability of the focus detection result by the phase difference detection method and the focus detection result by the contrast method. With the goal.

The imaging apparatus of the present invention includes an imaging unit that photoelectrically converts a subject image to generate a captured image, and includes focus detection based on a phase difference detection method and a contrast method based on the contrast of the subject image of the captured image obtained from the imaging unit. A reliability determination unit that determines a reliability that decreases when a result of focus detection by the phase difference detection method and a result of focus detection by the contrast method are separated from each other . A re-execution unit that re-executes focus detection by the phase difference detection method and focus detection by the contrast method according to the reliability determined by the reliability determination unit, and a result of focus detection by the phase difference detection method. and a controller to be corrected to the lens drive amount by the correction amount corresponding to the difference between the result of focus detection by the contrast method, When displaying an image shot in a shooting sequence for determining reliability, edge emphasis is not performed when displaying an image shot in a sequence other than the shooting sequence for determining reliability. Has characteristics.
An image pickup apparatus control method according to the present invention includes an image pickup unit that photoelectrically converts a subject image to generate a picked-up image. The focus detection by the phase difference detection method and the contrast of the subject image of the picked-up image obtained from the image pickup unit. A method of controlling an imaging apparatus capable of performing focus detection by a contrast method based on the image quality determination method, and determining reliability that decreases when a result of focus detection by the phase difference detection method and a result of focus detection by the contrast method are separated A procedure for re-execution of focus detection by the phase difference detection method and focus detection by the contrast method according to the determined reliability, and a result of focus detection by the phase difference detection method by the contrast method. and a procedure of the lens drive amount is corrected by a correction amount corresponding to the difference between the result of focus detection, Taking a determination of the reliability When displaying the captured image in the sequence is characterized in that not performed edge enhancement performed when displaying an image captured by the sequence non-imaging sequence for judging the reliability.
A computer program according to the present invention includes an imaging unit that photoelectrically converts a subject image to generate a captured image, and includes focus detection based on a phase difference detection method and a contrast method based on the contrast of the subject image of the captured image obtained from the imaging unit. A computer program for controlling an imaging apparatus capable of performing focus detection by means of determining a reliability that decreases when a result of focus detection by the phase difference detection method and a result of focus detection by the contrast method are separated And a process of re-execution of focus detection by the phase difference detection method and focus detection by the contrast method according to the determined reliability, and a result of focus detection by the phase difference detection method as a focus by the contrast method. and processing for the correction to the lens drive amount by the correction amount corresponding to the difference between the result of the detection Con When the image captured in the imaging sequence for determining the reliability is displayed and the image captured in the sequence other than the imaging sequence for determining the reliability is displayed, edge enhancement is performed. It has a feature in that it is not performed.

  According to the present invention, a highly accurate AF function can be realized by determining the reliability of the focus detection result by the phase difference detection method and the focus detection result by the contrast method.

  Furthermore, the autofocus correction amount is acquired and stored in the storage means during the step shooting mode, and the autofocus correction amount stored in the storage means is reflected in the focus detection result by the phase difference detection method in the normal shooting mode. By doing so, a test mode only for acquiring relative shift data of autofocus as in Patent Document 1 is not required, and focus detection by a phase difference detection method is performed for each normal photographing as in Patent Document 2. And the focus detection by the contrast method need not be performed.

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.
(Configuration of electronic camera)
FIG. 1 shows a schematic configuration of the electronic camera of the present embodiment. The lens unit 100 is detachably attached to the camera body 200 of the electronic camera via a mount unit. The mount portion is provided with an electrical contact group 107, which communicates between the camera body 200 and the lens unit 100 to drive the lens 101 and the diaphragm 102 of the lens unit 100.

  A light beam from a subject image (not shown) is guided to a quick return mirror (main mirror) 202 through a photographing lens 101 and a diaphragm 102 which is an exposure unit for adjusting the amount of light. The quick return mirror 202 is assembled so that the mirror can be raised and lowered.

  The central portion of the quick return mirror 202 is a half mirror, and a part of the light flux from the photographing lens 101 is transmitted when the quick return mirror 202 is down (the state shown in FIG. 1). The transmitted light beam is reflected by the sub mirror 203 installed on the quick return mirror 202 and guided to the AF sensor 204. As shown in FIG. 6, the AF sensor 204 can detect the focus at a plurality of positions (ranging areas 1 to 3) on the photographing screen. On the other hand, the light beam reflected by the quick return mirror 202 reaches the eyes of the photographer via the pentaprism 201 and the eyepiece lens 206.

  On the other hand, in a state where the quick return mirror 202 is up, the light beam from the photographing lens 101 is an image that is an imaging means represented by a CMOS or the like as an image sensor via a filter 209 and a focal plane shutter 208 that is a mechanical shutter. The sensor 210 is reached. The filter 209 has two functions. One is a function of cutting infrared rays and guiding only visible light to the image sensor 210, and the other is a function as an optical low-pass filter. The focal plane shutter 208 is a light shielding unit that has a front curtain and a rear curtain, and controls transmission and blocking of the light beam from the photographing lens 101. When the quick return mirror 202 is raised, the sub mirror 203 is folded.

  The electronic camera according to the present embodiment includes a system controller 223 configured by a CPU as a control unit that performs overall control, and appropriately controls the operation of each unit described below. The system controller 223 is connected to the lens control circuit 104, the aperture control circuit 106, the shutter charge / mirror drive mechanism 211, the shutter control mechanism 212, the photometry circuit 207, the EEPROM 222, and the like. In the present embodiment, the system controller 223 can also control AF, AE, and white balance stage shooting.

  The lens control circuit 104 controls a lens driving mechanism 103 for moving the photographing lens 101 in the optical axis direction and performing focusing. The lens control circuit 104 also includes lens storage means for storing information unique to the lens, such as information such as focal length, wide aperture, lens ID assigned to each lens, and information received from the system controller 223. A diaphragm control circuit 106 controls a diaphragm driving mechanism 105 for driving the diaphragm 102.

  The shutter charge / mirror drive mechanism 211 controls the up / down drive of the quick return mirror 202 and the shutter charge of the focal plane shutter 208. A shutter control mechanism 212 controls the traveling of the front curtain and rear curtain of the focal plane shutter 208. That is, the drive source of the front and rear curtains of the focal plane shutter 208 is constituted by a spring, and after the shutter travels, a spring charge is required for the next operation. The shutter charge / mirror drive mechanism 211 The spring charge is controlled.

  The photometric circuit 207 is an automatic exposure adjustment unit connected to a photometric sensor disposed in the vicinity of the eyepiece lens 206. The photometric sensor connected to the photometric circuit 207 is a sensor for measuring the luminance of the subject, and its output is supplied to the system controller 223 via the photometric circuit 207. As shown in FIG. 6, the photometry unit of the photometry sensor is divided so that the photographing screen can be divided and photometry can be performed. In this case, the photometry areas 1 to 3 correspond to the distance measurement areas 1 to 3, respectively.

  The EEPROM 222 stores parameters that need to be adjusted to control the electronic camera, camera ID information that enables individual identification of the electronic camera, AF correction data, and automatic exposure correction values.

  An external control device 300 represented by a personal computer (PC) can be connected to the electronic camera, and the external control device 300 and the system controller 223 can communicate with each other via a communication interface circuit 224. .

  The system controller 223 forms a subject image on the image sensor 210 by controlling the lens driving mechanism 103 via the lens control circuit 104. Further, the system controller 223 controls the aperture driving mechanism 105 that drives the aperture 102 based on the set Av value, and further outputs a control signal to the shutter control mechanism 212 based on the set Tv value.

  An image data controller 220 is connected to the system controller 223. The image data controller 220 is correction data sampling means and correction means constituted by a DSP (digital signal processor). The system controller 223 controls the image sensor 210 and corrects or processes the image data input from the image sensor 210. Execute based on the command. Auto white balance is also included in the items of image data correction and processing. Auto white balance is a function that corrects a portion of maximum brightness in a captured image to a predetermined color (white). In auto white balance, the correction amount can be changed by a command from the system controller 223.

  In addition, a timing pulse generation circuit 217, an A / D converter 216, a DRAM 221, a D / A converter 215, and an image compression circuit 219 are connected to the image data controller 220.

  The timing pulse generation circuit 217 outputs a pulse signal necessary for driving the image sensor 210. The A / D converter 216 receives the timing pulse generated by the timing pulse generation circuit 217 together with the image sensor 210, and converts an analog signal corresponding to the subject image output from the image sensor 210 into a digital signal.

  The DRAM 221 is used as a storage unit for temporarily storing image data (digital data) before processing or data conversion into a predetermined format.

  The D / A converter 215 is connected to an image display circuit 213 that is an image display unit via an encoder circuit 214. The image display circuit 213 is a circuit for displaying image data picked up by the image sensor 210 and is generally configured by a color liquid crystal display element.

  An image data recording medium 218 is connected to the image compression circuit 219. The image compression circuit 219 is a circuit for performing compression and conversion (for example, JPEG) of image data stored in the DRAM 221. The converted image data is stored in the image data recording medium 218. As the image data recording medium 218, a hard disk, a flash memory, a flexible disk, or the like is used.

  The image data controller 220 converts the image data on the DRAM 221 into an analog signal by the D / A converter 215 and outputs the analog signal to the encoder circuit 214. The encoder circuit 214 converts the output of the D / A converter 215 into a video signal (for example, an NTSC signal) necessary for driving the image display circuit 213.

  Further, the system controller 223 includes a display circuit 225, a release switch 1 (231), a release switch 2 (230), a mode setting switch 229, a distance measurement area selection switch 228, a determination switch 227, and a bracket amount. A bracket amount setting switch 232 for setting, a photometric area selection switch 235, and an electronic dial switch 226 are connected.

  The display circuit 225 displays information on the operation mode of the electronic camera and exposure information (shutter time, aperture value, etc.). The release switch 1 (231) is used to start shooting preparation operations such as photometry and distance measurement, and the release switch 2 (230) is used to start imaging operations. The mode setting switch 229 is for the user to set a mode so that the electronic camera performs a desired operation. The ranging area selection switch 228 is a focus detection position selection means for selecting a focus detection position to be used from a plurality of focus detection positions of the AF sensor 204. The decision switch 227 also functions as an image selection unit. The photometric area selection switch 235 is for selecting a photometric area to be used. The electronic dial switch 226 is for displaying the parameters up and down by a rotating operation.

  The counter 233 is connected to the system controller 223 and counts the number of times of release when performing various bracket photography. The counter value of the counter 233 is reset by the system controller 223. The buzzer 234 is for generating a warning sound or the like.

(Explanation of defocus detection principle)
The principle of defocus amount (focus position shift amount) detection will be described with reference to FIGS. When the image sensor is in focus, the interval between the two images on the line sensor takes a certain value. This value can be determined by design, but in practice, it is not the same as the design value due to the size, variation, and assembly error of parts. Therefore, it is difficult to obtain the two-image interval (reference two-image interval Lo) unless actually measured. As is apparent from FIG. 7, if the two image intervals are narrower than the reference two image interval Lo, it is a front pin, and if it is larger than the reference two image intervals Lo, it is a rear pin.

  FIG. 8 is a diagram illustrating a model in which a condenser lens is omitted from the optical system of the AF sensor module. As shown in the figure, when the chief ray angle is θ, the separator lens magnification is β, the image movement amount is ΔL, and ΔL ′, the defocus amount L is obtained by the following equation (1). Here, β · tan θ is a parameter determined in the design of the AF sensor module. ΔL ′ can be obtained from the reference two-image interval (Lo) and the current two-image interval (Lt).

  The AF sensor 204 of this embodiment has a plurality of the above-described configurations so that focus detection can be performed at a plurality of positions on the shooting screen. The focus adjustment of the autofocus function uses a lens whose focus position is known in advance, and the two image intervals obtained from the AF sensor 204 so that the focus position comes to a position on the optical axis of the image sensor (assembly error of the image sensor). Are stored in the EEPROM 222 as AF focus correction parameters. However, when the lens unit attached to the electronic camera changes, the focus position varies due to manufacturing errors of the lens unit itself.

(Ranging area selection sequence)
A ranging area selection sequence will be described with reference to FIG. In step S001, it is determined whether or not the ranging area selection switch 228 is turned on. If turned on, the process proceeds to step S002. In step S002, it is detected whether or not the electronic dial switch 226 has been operated, and if it has been operated, the operation direction and the operation amount are detected. In step S003, the distance measurement area is changed according to the operation direction and operation amount of the electronic dial switch 226 in step S002. The ranging areas are switched in the order of all of the ranging areas 1, the ranging area 2, and all the ranging areas 3. In step S004, it is determined whether or not the ranging area selection switch 228 has been turned off. If it has been turned off, the ranging area selection sequence is terminated.

(Shooting mode setting sequence)
The shooting mode setting sequence will be described with reference to FIG. In step S101, it is determined whether or not the mode setting switch 229 is turned on. If it is turned on, it is determined that the mode setting operation has been started by the user, and the process proceeds to step S102. In step S102, the number of operation clicks of the electronic dial switch 226 is detected. When an electronic dial (not shown) that turns on / off the electronic dial switch 226 is rotated in a certain direction, the shooting mode is changed from “TV” → “AV” → “P” → “AF calibration” → “TV” for each operation click. "... can be changed. When the electronic dial (not shown) is rotated in the reverse direction, the selection mode is changed from “TV” → “AF calibration” → “P” → “AV” → “TV”. be able to. “AF calibration” is not displayed unless only one of the ranging areas 1 to 3 is selected in the ranging area selection sequence, and the mode cannot be selected.

  In step S103, it is determined whether or not the mode setting switch 229 is turned off. If it is turned off, the shooting mode selected at that time is selected. In step S104, the shooting mode is determined to be the shooting mode selected in step S103.

  In step S105, it is determined whether or not the shooting mode is an AF calibration mode. In cases other than the AF calibration mode, the process proceeds to step S111, and the process proceeds to a shooting sequence (not shown) corresponding to each shooting mode.

  In the AF calibration mode, the process proceeds to step S106. In step S106, it is determined whether or not the bracket amount setting switch 232 is turned on. If turned on, the process proceeds to step S107. If it is not turned on, the AF bracket step amount at the time of AF calibration shooting is set to the reference set value a, and then the process proceeds to step S110 and proceeds to the AF calibration shooting sequence.

  In step S107, the number of operation clicks of the electronic dial switch 226 is detected. When an electronic dial (not shown) for turning on / off the electronic dial switch 226 is rotated in an arbitrary direction, the AF bracket step amount is changed from “reference value a × 0.25” to “reference value a × 0. 5 ”⇔“ reference value a ”⇔“ reference value a × 2 ”⇔“ reference value a × 4 ”. However, “reference value a × 0.25” and “reference value a × 4” are set as upper and lower limits, respectively, and even if the electronic dial is operated to change the upper limit and lower limit values, they are ignored.

  The reference value a for the AF bracket step amount is determined by a = FNO × ε when the system controller 223 receives open aperture value information from the aperture control circuit 106. FNO is aperture value information, and ε is an allowable circle of confusion. The reference value a in the present embodiment is the same value as the focal depth δ. In the present embodiment, ε = 0.03 mm.

  By making the AF bracket step amount variable, the following becomes possible. In other words, even when large focus correction is required, AF calibration is performed multiple times by changing the AF bracket step amount stepwise (from a large step amount to a small step amount). You can narrow down to the value.

  In step S108, it is determined whether or not the bracket amount setting switch 232 is turned off. If it is turned off, the AF bracket step amount selected at that time is selected. In step S109, the AF bracket step amount A is determined to be the bracket step amount selected in step S108, and then the process proceeds to step S110 to proceed to the AF calibration imaging sequence in FIG.

(AF calibration shooting sequence)
The AF calibration shooting sequence will be described with reference to FIG. The AF calibration imaging sequence is controlled by a system controller 223 that functions as a stage imaging unit.

  In step S201, the counter 233 is reset. In step S202, it is determined whether or not release switch 1 (231) is turned on. If it is turned on, the process branches to step S203 and step S205 and shifts.

  In step S203, the photometric circuit 207 measures the light beam that has passed through the taking lens 101, reflected by the quick return mirror 202, and passed through the pentaprism 201. In step S <b> 204, the system controller 223 determines the exposure amount at the time of imaging according to the output of the photometry circuit 207.

  In step S205, the system controller 223 uses the AF sensor 204 and the focus detection circuit 205 to perform distance measurement. In step S206, it is determined whether distance measurement has been performed. If the measured object is low contrast or dark, distance measurement may not be possible. In this case, the process proceeds to step S210 to give a warning.

  In step S207, the lens is driven to the focus position obtained by the phase difference AF. In step S208, the focus peak position is obtained by contrast AF. In other words, the contrast of the captured image is detected at each focus position while moving the focus position of the photographing lens 101 stepwise, and the maximum contrast position (peak position) is used as a focus detection result (so-called TV-AF or hill-climbing AF). Method called).

  In step S209, the difference between the focus position obtained in step S205 and the focus peak position obtained in step S208 is obtained, and the reliability of the focus detection result by the phase difference AF and the focus detection result by the contrast AF is determined in advance. Judgment is made according to established criteria.

  If the focus position results of the phase difference AF and the contrast AF are greatly different (for example, if the difference between the results of the phase difference AF and the contrast AF is greater than or equal to the set value), there is an error in detection of any focus. Since it is possible, focus detection is executed again. At this time, not only the re-execution but also the conditions and determination criteria may be changed.

  Also, if the conditions at the time of focus detection such as chart, distance, and light source are detected, and the conditions are significantly different from the reference conditions, it is determined that the obtained result is not reliable. You may do it.

  An example of the determination of the reliability is shown in FIG. In FIG. 11, in step S601, the chart being used is read first. In step S602, the chart used is compared with the chart pattern as a reference, and if it is determined to be the same, the process proceeds to step S603, and if it is determined to be different, the process proceeds to step S608. It is determined that the reliability is low. For example, this is a case where a double bar chart or a high contrast chart should be used but a low contrast chart is used by mistake.

  In step S603, the shooting distance to the subject to be measured is measured. This can be determined by determining how large the standard chart is. If this is the same as the reference distance (for example, 50 times the focal length) in step S604, and if it is determined that it is the same as the reference distance, the process proceeds to step S605 and is different. If it determines, it will transfer to step S608 and will determine with reliability being low.

  In step S605, a light source to be measured is detected. The light source may be detected by an existing method described in Patent Document 7, for example. In step S606, whether the light source is the same as the reference light source is compared, and if it is determined that the light source is the same as the reference light source, the process proceeds to step S607, where the reliability is determined to be high and is different. If it determines, it will transfer to step S608 and will determine with reliability being low.

  In the example described in FIG. 11, if even one of the conditions is different, the reliability is determined to be low. However, depending on how many of the same conditions are provided, the reliability is weighted. It may be. For example, if all three are determined to have the same condition, the reliability level is high. If two are determined to be the same condition, the reliability level is medium, and one is the same condition. If it is determined, the level of reliability is low. If it is determined that the reliability is low, a message to that effect may be displayed.

  As another method, the result of focus detection by phase difference AF is obtained from a correlation value, and the result of focus detection by contrast AF is what kind of locus the evaluation value locus for obtaining a peak of a mountain draws. Thus, the determination may be made. For example, the evaluation value locus usually draws a mountain shape, but if the locus is a locus that draws two mountain shapes, it is determined that the reliability is low. Further, it is determined that the reliability is low when the evaluation value trajectory does not draw a mountain shape.

  Further, not only the determination of the reliability level but also the reliability level may be quantified. The slope of the mountain locus of the evaluation value in contrast AF is obtained, and the reliability is expressed as a numerical value. For example, the case where the inclination is 45 ° is determined as an ideal form, and is treated as having the highest reliability, and then the degree of reliability decreases as the inclination changes in a steep or gentle direction. Become.

  Further, as another method of measuring the reliability, a method of obtaining from the absolute value of the obtained evaluation value is also conceivable. In this case, the evaluation value of the place that becomes the focus peak is treated as the highest value, and the degree of reliability decreases as the absolute value decreases from there.

  Further, it depends on how far the contrast peak is detected from the in-focus position in the phase difference AF. If the far away position is the result, the degree of reliability decreases according to the degree of separation.

  The reliability may be expressed by various methods without being limited to the methods described above. Further, when focus detection is re-executed, it is conceivable to change conditions or change a criterion. The change can be made by loosening the reliability criterion, or changing the chart, distance, and light source settings to a more strict setting direction as measurement setting conditions.

Returning to FIG. 4, in step S211, it is determined whether or not the release switch 2 (230) is turned on. If turned on, the process proceeds to step S212. In step S212, the system controller 223 calculates the focus position shift amount DF. Specifically, the current count number N is received from the counter 233, and the focus position shift amount DF is calculated according to the following equation (2).
DF = A × (N−4) (2)

  In step S213, the counter N is incremented by one. In step S214, the system controller 223 sends the focus position shift amount DF calculated in step S212 to the lens control circuit 104. In response to this, the lens control circuit 104 controls the lens driving circuit 103 to drive the photographing lens 101 to the position of the focus position shift amount DF.

  In step S215, the system controller 223 controls the shutter charge / mirror drive mechanism 211 to perform mirror up. In step S216, the system controller 223 transmits the exposure amount set in step S204 to the aperture control circuit 106, drives the aperture drive mechanism 105, and narrows down to the set aperture value.

  In step S217, the system controller 223 controls each unit to open the focal plane shutter 208. In step S218, the image data controller 220 is instructed to perform an integration operation of the image sensor 210. In step S219, the process waits for a predetermined integration time. When the integration time is over, the process proceeds to step S220, and the focal plane shutter 208 is closed.

  In step S221, the system controller 223 performs the charge operation of the focal plane shutter 208 and the mirror down drive in preparation for the next operation. In step S222, the aperture is driven to open.

  In step S223, the image data controller 220 is instructed to capture image data from the image sensor 210. At this time, the image data captured from the image sensor 210 may be image data of a limited area including a distance measuring point used for AF.

  In step S224, the current focus position shift amount DF is transmitted to the image data controller 220, and the lens ID information, the image data, and the focus position shift amount DF are associated with each other and are recorded on the image data recording medium 218 through the image compression circuit 219. .

  In step S225, the value of the counter N is confirmed. If the counter value is a predetermined value (“7” in this embodiment), it is determined that the AF calibration imaging sequence is completed, and the process proceeds to the image selection sequence in FIG.

(AF calibration image selection sequence)
The AF calibration image selection sequence will be described with reference to FIG. In step S3000, the selection method is determined, and if it is manual, the process proceeds to step S301, and if it is automatic, the process proceeds to step S3001.

  In step S3001, the contrast evaluation value of the image is fetched. In step S3002, the images are compared, the image having the maximum value is selected, and the process proceeds to step S313.

  On the other hand, in step S301, the system controller 223 controls the image data controller 220 to display the image data of the counter “1” captured in the AF calibration imaging sequence on the image display circuit 213. When the image data is displayed, the image data is displayed after being subjected to image processing different from that for displaying an image shot in the normal shooting sequence. Specifically, when displaying an image shot in the normal shooting sequence, edge enhancement is performed to improve the appearance. However, when edge enhancement is performed on image data captured in the AF calibration mode, an image portion that should have been out of focus originally appears to be in focus. Therefore, when selecting an optimally focused image from a group of images taken in AF calibration mode, avoid the inconvenience of selecting an image that is out of focus by mistake without performing edge enhancement. ing.

  In step S302, it is determined whether or not the decision switch 227 is turned on. If turned on, the process proceeds to step S313, and if not turned on, the process proceeds to step S303. In step S303, the operating state of the electronic dial switch 226 is detected. If it is rotated left, the process proceeds to step S304, and if it is rotated right, the process proceeds to step S308.

  In step S304, the counter N is decremented by one. In step S305, it is determined whether the counter N is “0”. If the counter N is smaller than “0” in step S305, a warning is given in step S306 by using the display circuit or the buzzer 234 or the display circuit and the buzzer 234 at the same time that there is no image data by AF calibration shooting that can be selected and displayed. . Thereafter, in step S307, the counter N is incremented by one. If the counter N is greater than “0” in step S305, the process proceeds to step S312.

  In step S308, the counter N is incremented by one. In step S309, it is determined whether the counter N has increased by “7”. If the counter N is larger than “7” in step S309, a warning is issued in step S310 by using the display circuit or the buzzer 234, or the display circuit and the buzzer 234 at the same time, indicating that there is no AF calibration image data that can be selected and displayed. . Thereafter, in step S311, the counter N is decremented by one. If the counter N is “7” or less in step S309, the process proceeds to step S312.

  In step S312, image data corresponding to the counter N changed according to the operation of the electronic dial switch 226 is called from the image data recording medium 218 and displayed on the image display circuit 213.

  In step S313, the focus position shift amount DF stored in association with the image data obtained by AF calibration photographing selected in step S3002 or step S302 is determined as the AF correction amount (CAL data). In step S314, the determined AF correction amount (CAL data) is written into the EEPROM 222 together with the lens ID of the lens control circuit 104 in association with the focus detection area and zoom position where focus detection has been performed.

  In step S 315, all the AF calibration image data and the AF calibration image data folder are deleted from the image data recording medium 218.

(Normal shooting sequence)
The normal shooting sequence will be described with reference to FIG. In step S401, it is determined whether or not the release switch 1 (231) is turned on. If it is turned on, it branches to step S402 and step S404, and shifts.

  In step S <b> 402, the light beam reflected by the quick return mirror 202 through the photographing lens 101 and passing through the pentaprism 201 is measured by the photometric circuit 207. In step S <b> 403, the system controller 223 determines the exposure amount at the time of imaging according to the output of the photometry circuit 207.

  In step S <b> 404, the system controller 223 uses the AF sensor 204 and the focus detection circuit 205 to perform distance measurement. In step S405, it is determined whether distance measurement has been performed. If the measured object is low contrast or dark, distance measurement may not be possible. In this case, the process proceeds to step S409 and a warning is given.

  In step 406, the system controller 223 receives the lens ID information, and the AF correction amount (CAL data) of the distance measuring area used for focus detection is the lens attached to the electronic camera (determined by the lens ID). Is stored in the EEPROM 222. If it is not stored, the AF correction amount is not added to the focus detection result. If stored, the AF correction amount (CAL data) is added to the distance measurement result in step S407, and the process proceeds to step S408. In this case, the lens driving amount is lens driving amount = distance measurement result + AF correction value (adjustment data) at the time of manufacture + AF correction amount (CAL data).

  In step S408, the lens driving amount is transmitted from the system controller 223 to the lens control circuit 104 based on the distance measurement result. The lens control circuit 104 controls the lens driving mechanism 103 based on the transmitted lens driving amount, and the lens driving mechanism 103 drives the photographing lens 101 to the in-focus position.

  In step S410, it is determined whether release switch 2 (230) is turned on. If turned on, the process proceeds to step S411. In step S411, the system controller 223 controls the shutter charge / mirror drive mechanism 211 to perform mirror up. In step S412, the system controller 223 transmits the aperture value information set in step S204 to the aperture control circuit 106, drives the aperture drive mechanism 105, and narrows down to the set aperture value.

  In step S413, the system controller 223 controls each unit to open the focal plane shutter 208. In step S414, the image data controller 220 (DSP) is instructed to perform an integration operation of the image sensor 210. In step S415, the system waits for a predetermined integration time. When the integration time is over, the process proceeds to step S416, and the focal plane shutter 208 is closed.

  In step S417, the system controller 223 performs the charge operation of the focal plane shutter 208 and the mirror down drive in preparation for the next operation. In step S418, the aperture is driven to open.

  In step S419, the image data controller 220 is instructed to capture image data from the image sensor 210. In step S 420, the read image data is recorded on the image data recording medium 218 through the image compression circuit 219.

(Outline of processing operation according to the present invention)
FIG. 10 shows an outline of the processing operation according to the present invention. In step S1000, lens mounting is detected. If it is mounted, lens information is acquired in step S1010.

  Next, in step S1020, it is determined whether or not release switch 1 (231) has been pressed. If it has been pressed, the process proceeds to step S1030. In step S1030, lens driving by phase difference AF is first performed. In step S1040, live view display is started. Next, in step S1050, lens driving by imager AF (contrast AF) is performed. The conditions (distance, chart, light source) set at this time are detected and stored.

  In step S1060, a difference between the results of both AFs is detected, and in step S1070, reliability is determined. At this time, the reliability is determined according to the condition when the contrast AF result is obtained and the difference from the phase difference AF result.

  In step S1080, it is detected whether or not release switch 2 (230) has been pressed. If it has been pressed, the process proceeds to step S1090. If release switch 2 (230) is not pressed, the process returns to step S1020. In step S1090, the live view display ends, and in step S1100, the focus position shift amount associated with the selected image is stored as an AF correction amount. Based on the result, the subsequent shooting is performed in step S1110.

  As described above, a highly accurate AF function can be realized by determining the reliability of the focus detection result by the phase difference AF and the focus detection result by the contrast AF.

  In addition, if notification such as high or low reliability or a numerical value is displayed or a warning is given when the reliability is low, the user can determine whether or not to use the AF correction amount. It becomes possible to provide information that is a guide.

  Also, whether or not the AF correction amount can be stored in the EEPROM 222 may be determined according to the reliability. In this case, by storing only when the reliability is high, the user can use the AF correction amount without being aware of the reliability.

  Further, if the AF correction amount is acquired again according to the reliability, the AF correction amount with higher reliability can be obtained.

  An object of the present invention is to supply a storage medium storing software program codes for realizing the functions of the above-described embodiments to a system or apparatus, and the computer (or CPU or MPU) of the system or apparatus stores the storage medium. Needless to say, this can also be achieved by reading and executing the program code stored in.

  In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the program code itself and the storage medium storing the program code constitute the present invention.

  As a storage medium for supplying the program code, for example, a flexible disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.

  Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an OS (basic system or operating system) running on the computer based on the instruction of the program code. Needless to say, a case where the functions of the above-described embodiment are realized by performing part or all of the actual processing and the processing is included.

  Further, after the program code read from the storage medium is written to a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the function expansion is performed based on the instruction of the program code. It goes without saying that the CPU or the like provided in the board or function expansion unit performs part or all of the actual processing, and the functions of the above-described embodiments are realized by the processing.

It is a block diagram which shows schematic structure of the electronic camera of this embodiment. It is a flowchart for demonstrating a ranging area selection sequence. It is a flowchart for demonstrating a mode setting sequence. It is a flowchart for demonstrating AF calibration imaging | photography sequence. It is a flowchart for demonstrating AF calibration picked-up image selection sequence. It is a figure which shows the relationship between a finder observation image, a ranging area, and a photometry area. It is a figure for demonstrating the principle of a defocus amount detection. It is a figure for demonstrating the principle of a defocus amount detection. It is a flowchart for demonstrating a normal imaging | photography sequence. It is the flowchart which showed the outline | summary of the processing operation by this invention. It is the flowchart which showed the outline | summary of the reliability determination by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100: Lens unit 101: Shooting lens 102: Diaphragm 103: Lens drive mechanism 104: Lens control circuit 105: Diaphragm drive mechanism 106: Diaphragm control circuit 107: Electrical contact group 200: Camera body 201: Penta prism 202: Quick return mirror 203: Sub mirror 204: AF sensor 206: Eyepiece lens 207: Photometric circuit 208: Focal plane shutter 209: Filter 210: Image sensor 211: Shutter charge / mirror drive mechanism 212: Shutter control circuit 213: Image display circuit 214: Encoder circuit 215 : D / A converter 216: A / D converter 217: Timing pulse generation circuit 218: Image data recording medium 219: Image compression circuit 220: Image data controller 221: DRAM
222: EEPROM
223: System controller 224: Communication interface circuit 225: Operation display circuit 226: Electronic dial switch 227: Determination switch 228: Ranging area selection switch 229: Mode setting switch 230: Release switch 2
231: Release switch 1
232: Bracket amount setting switch 233: Counter 235: Photometry area selection switch 300: External control device

Claims (8)

An imaging unit that photoelectrically converts a subject image to generate a captured image;
An imaging apparatus capable of performing focus detection by a phase difference detection method and focus detection by a contrast method based on the contrast of a subject image of a captured image obtained from the imaging means,
Reliability determination means for determining reliability that decreases when the result of focus detection by the phase difference detection method and the result of focus detection by the contrast method are separated ;
Re-execution means for re-executing focus detection by the phase difference detection method and focus detection by the contrast method according to the reliability determined by the reliability determination means ;
A controller that corrects the result of focus detection by the phase difference detection method with a correction amount according to the difference from the result of focus detection by the contrast method and sets the lens drive amount ;
When displaying an image shot in a shooting sequence for determining the reliability, edge enhancement performed when displaying an image shot in a sequence other than the shooting sequence for determining the reliability is not performed. An imaging device that is characterized.   The imaging apparatus according to claim 1, wherein the reliability is determined by the reliability determination unit in a staged shooting mode in which shooting is performed while gradually shifting the focal position.   The imaging apparatus according to claim 2, wherein a focus position shift amount selected from a plurality of focus position shift amounts in the stepwise shooting mode is stored in a storage unit as an autofocus correction amount.   The imaging apparatus according to claim 3, wherein in the normal photographing mode, only focus detection by the phase difference detection method is executed, and an autofocus correction amount stored in the storage unit is reflected in the result. The imaging apparatus according to claim 1-4, characterized in that it comprises a notifying means for notifying the reliability determined by said reliability determining means.   The imaging apparatus according to claim 3, wherein whether or not storage in the storage unit is possible is determined according to the reliability determined by the reliability determination unit. Includes imaging means that photoelectrically converts the subject image to generate a captured image, and can perform focus detection by the phase difference detection method and focus detection by the contrast method based on the contrast of the subject image of the captured image obtained from the imaging means A control method for an image pickup apparatus,
A procedure for determining a reliability that decreases when a result of focus detection by the phase difference detection method and a result of focus detection by the contrast method are separated from each other ;
In accordance with the determined reliability, a procedure for re-execution of focus detection by the phase difference detection method and focus detection by the contrast method ;
A step of correcting the focus detection result by the phase difference detection method with a correction amount according to the difference from the focus detection result by the contrast method to obtain a lens driving amount ,
When displaying an image shot in a shooting sequence for determining the reliability, edge enhancement performed when displaying an image shot in a sequence other than the shooting sequence for determining the reliability is not performed. A control method for an imaging apparatus. Includes imaging means that photoelectrically converts the subject image to generate a captured image, and can perform focus detection by the phase difference detection method and focus detection by the contrast method based on the contrast of the subject image of the captured image obtained from the imaging means A computer program for controlling an image pickup apparatus,
A process of determining reliability that decreases when a result of focus detection by the phase difference detection method and a result of focus detection by the contrast method are separated from each other ;
In accordance with the determined reliability , processing for re-execution of focus detection by the phase difference detection method and focus detection by the contrast method ;
Causing the computer to execute a process of correcting the focus detection result by the phase difference detection method with a correction amount according to the difference from the focus detection result by the contrast method to obtain a lens driving amount ,
When displaying an image shot in a shooting sequence for determining the reliability, edge enhancement performed when displaying an image shot in a sequence other than the shooting sequence for determining the reliability is not performed. A featured computer program.

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