JP6202843B2 - Imaging device - Google Patents

Description

  The present invention relates to an image mounted on a digital still camera, a digital video camera, or a mobile phone that performs focus adjustment using an image signal acquired by an image sensor that photoelectrically converts a subject image formed by an imaging optical system. It relates to the device.

  2. Description of the Related Art Conventionally, there is an imaging apparatus provided with a manual focus (MF) mode in which a user can manually specify a focus lens position and perform shooting. Some MF modes have a function (hereinafter referred to as safety MF) that assists focusing by performing autofocus (AF) in a minute range including a focus lens position designated by the user.

  On the other hand, as one of the weak scenes in AF using a method in which the lens position where the high frequency component (hereinafter referred to as a focus evaluation value) of the luminance signal obtained from the image sensor is maximized is used as a focus position, high luminance There is a subject. For a normal subject, as shown in FIG. 12A, when the focus is defocused from the focus position, the subject image is blurred and the contrast is lowered, so that the focus evaluation value is maximized at the subject focus position.

  However, in a high-luminance subject, as shown in FIG. 12B, the subject image spreads while the luminance value is saturated from the focus position of the subject to a position defocused by a predetermined amount, so that the focus evaluation value is maximum at the focus position. Not. Depending on how the focus evaluation value is calculated, a focus evaluation value shape that forms a valley at the subject focus position can be obtained, so that an accurate focus position cannot be detected. As a result, in a high-luminance subject, the focusing performance cannot be assisted even if the above-described safety MF is performed after manual focusing by the user.

  Until now, an automatic focusing device that can perform an accurate focusing operation on a high-luminance subject has been proposed (Patent Document 1). This is done by comparing the area of the low-brightness or medium-brightness part of the video signal on the imaging screen to determine a high-brightness subject, and the focusing operation for a general subject is performed using a contrast signal. In the case of a luminance subject, the focusing operation is performed so that the area of the high luminance signal is reduced.

  In addition, when the focus position cannot be detected after the AF search operation with an appropriate exposure in a high-brightness subject, the saturation of the brightness value is avoided by performing the AF search operation again after reducing the exposure amount than the appropriate exposure, A method that enables accurate focusing control has been proposed (Patent Document 2).

Japanese Patent Registration No. 3105334 JP 2002-196220 A

  The method of Patent Document 1 is good if the main subject is composed of only a high-brightness subject, but if the high-brightness subject and an illuminated normal subject are mixed, accurate focus adjustment may not be possible. Further, in the method of Patent Document 2, since a fundamental problem is that a position that is not the in-focus position is erroneously determined as the in-focus position due to the influence of a high-luminance subject, a countermeasure is taken when the in-focus position cannot be detected There is no point in going. In addition, when multiple AF searches are performed with appropriate exposure and exposure lower than appropriate, the time required for AF becomes longer, and there is a problem that appearance is deteriorated because exposure is lower than appropriate.

  An object of the present invention is to provide an imaging device that can assist a user in focusing and improve focusing performance by performing safety MF suitable for a high-brightness subject even if the subject includes a high-brightness subject. It is to be.

Therefore, in the present invention, an image sensor that captures a subject image formed by a photographing optical system including a focus lens, manual focus means that can move the focus lens based on a manual operation, and the manual focus The focus evaluation value indicating the contrast of the focus detection area is calculated based on the image data output from the image sensor based on the position of the focus lens moved by the manual focus after the manual focus is executed by the means. And an automatic focus adjustment unit that adjusts the position of the focus lens in accordance with the focus evaluation value, and a determination unit that determines whether or not an object having a brightness higher than a predetermined value exists in the focus detection region. have the automatic focus adjusting means, higher than said predetermined value in the focus detection area bright If it is determined that there is a subject having a brightness higher than a predetermined value in the focus detection area, the focus evaluation value sampling interval and the focus evaluation value At least one of the movement ranges of the focus lens when sampling the focus evaluation value is widened .

  Even in a shooting scene including a high-luminance subject, focusing performance can be improved by assisting the user in focusing with the safety MF.

It is a block diagram which shows the structure of the imaging device to which the Example of this invention is applied. It is a flowchart figure explaining operation | movement of the imaging device to which the Example of this invention is applied. It is a flowchart figure explaining the high-intensity subject determination in FIG. 2 to which the Example of this invention is applied. It is a flowchart figure explaining the histogram Yp and MM calculation in FIG. 3 to which the Example of this invention is applied. It is a flowchart figure explaining the safety MF operation | movement in FIG. 2 to which the Example of this invention is applied. It is a flowchart figure explaining AF scan in FIG. 5 to which the Example of this invention is applied. It is a flowchart figure explaining the normal focusing determination in FIG. 5 to which the Example of this invention is applied. It is a flowchart figure explaining the high-intensity subject focusing determination in FIG. 5 to which the Example of this invention is applied. It is a figure explaining the method of the focus determination in FIG.7 and FIG.8. It is a figure explaining the focus evaluation value peak shape of the low region in a high-intensity subject. It is a figure explaining the focus evaluation value peak shape of the high region in a high-intensity subject. It is a figure explaining the influence which a high-intensity subject has on a focus evaluation value.

  Embodiments of the present invention will be described below with reference to FIGS. FIG. 1 is a block diagram showing the configuration of an electronic camera to which an embodiment of the present invention is applied.

  101 is a photographic lens as a photographic optical system including a zoom mechanism, 102 is a diaphragm and shutter for controlling the amount of light, 103 is an AE processing unit, 104 is a focus lens for focusing on an image sensor described later, and 105 is a focus lens. , 106 is an AF processing unit, 107 is an image sensor as a light receiving unit or photoelectric conversion unit that converts reflected light from an object into an electric signal, and 108 is a CDS circuit that removes output noise of the image sensor 107 or A An A / D conversion unit including a non-linear amplification circuit performed before / D conversion, 109 is an image processing unit, and 110 is a format conversion unit.

  The image sensor 107 captures a subject image formed by a photographing optical system including a focus lens.

  Reference numeral 111 denotes a high-speed built-in memory (for example, random access memory, hereinafter referred to as DRAM), 112 denotes an image recording unit including a recording medium such as a memory card and its interface, and 113 denotes a system control unit (hereinafter referred to as a shooting sequence) that controls the system. , A CPU), 114 an image display memory (hereinafter referred to as a VRAM), 115 an image display, a display for assisting operation and a display of the camera state, and a shooting screen and a distance measurement area at the time of shooting. An image display unit 116 to be displayed is an operation unit for operating the camera from the outside.

  The CPU 113 has a function as a focus evaluation value calculation unit that calculates a focus evaluation value indicating the contrast of a focus detection region set in advance based on image data output from the image sensor.

  The CPU 113 has a function as an automatic focus adjustment unit that adjusts the position of the focus lens so that the focus evaluation value becomes a peak position.

  The focus evaluation value calculation means calculates a plurality of focus evaluation values using a plurality of filters with different extracted bands.

  The CPU 113 has a function as execution means for executing automatic focus adjustment with reference to the position of the focus lens moved by the manual focus in response to an instruction from the instruction means after manual focus is executed by the manual focus means.

  The CPU 113 has a function as a determination unit that determines whether or not an object having a luminance higher than a predetermined value exists in the focus detection area.

  Reference numeral 117 denotes a shooting mode switch for selecting a shooting mode such as a macro mode, a distant view mode, and an MF mode. 118 denotes a main switch for turning on the system. 119 denotes a shooting standby operation such as AF or AE. The switch (hereinafter referred to as SW1), 120 is a photographing switch (hereinafter referred to as SW2) for performing photographing after the operation of SW1.

  The DRAM 111 is used as a high-speed buffer as temporary image storage means, or a working memory for image compression / decompression. The operation unit 116 includes, for example, the following. Menu switches for various settings such as shooting functions of the imaging device, settings for image playback, detailed settings for each shooting mode, zoom lever for instructing the zoom operation of the shooting lens, and the user manually operates the focus lens in the MF mode A focus lens operation button that can be used, an operation mode changeover switch between a shooting mode and a playback mode, and the like. The shooting mode switch 117 changes the distance measurement distance range, AF operation, etc. according to the shooting mode selected by the user.

  The operation of the embodiment of the present invention will be described in detail below with reference to FIGS. First, in S201, the AE processing unit 103 performs AE processing from the output of the image processing unit 109, and proceeds to S202. In S202, the state of SW1 is checked. If it is ON, the process proceeds to S203, and if not, the process proceeds to S201. In S203, after performing a high-luminance subject determination described later, the process proceeds to S204. In S204, it is determined whether or not the currently set shooting mode is the MF mode. If the shooting mode is the MF mode, the process proceeds to S205. Otherwise, the process proceeds to S207. In S205, it is checked whether or not the currently set photographing mode is the safety MF mode. If it is the safety MF mode, the process proceeds to S206, and if not, the process proceeds to S208. In S206, a safety MF operation to be described later is performed, and the process proceeds to S208.

  Here, the exposure conditions (shutter speed, aperture, sensitivity) during the safety MF operation are determined by the AE process of S201 immediately before. In S207, after performing a normal AF operation, the process proceeds to S208. Here, in the normal AF operation, the control may be changed based on the result of the high-luminance subject determination in S203, but the detailed operation is omitted because it differs from the main point of the present invention. In S208, the state of SW1 is checked. If it is ON, the process proceeds to S209, and if not, the process proceeds to S201. In S209, the state of SW2 is checked. If it is ON, the process proceeds to S210, and if not, the process proceeds to S208. In S210, after performing a photographing operation, the process proceeds to S201.

  FIG. 3 is a flowchart for explaining the high-luminance subject determination in S203 in FIG.

  First, in S301, a high brightness subject determination parameter is set according to subject brightness (Bv value), and the process proceeds to S302. Here, in the setting of the high-brightness subject determination parameter (constant), the determination that the high-brightness subject is included in the region is set so as to be easily made darker. The condition for determining that the region includes a high-luminance subject is that there are many low-luminance portions, some high-luminance portions exist, the high-luminance portions are very bright, and the contrast is high.

Specifically, it is determined that a high-luminance subject is included when all of the following (1) to (4) are satisfied.
(1) The sum of the number of low luminance pixels (NumBlightLow) and the number of high luminance pixels (NumBlightHigh) is greater than the predetermined number of pixels (NumHighLowPixs).
(2) The number of high luminance pixels (NumBlightHigh) is larger than the predetermined number of pixels (NumHighPixs).
(3) The histogram Yp representing the value of the high luminance part in the region is larger than the predetermined value (Yp0).
(4) The histogram MM representing the contrast in the region is larger than a predetermined value (MM0).

  Therefore, these conditions are relaxed as the Bv value decreases. That is, NumHighLowPixs and NumHighPixs are set to smaller values as the Bv value decreases. Yp0 is set to the same value regardless of the luminance, but MM0 is set so as to increase as the Bv value decreases in order to avoid erroneous determination. In addition, the value regarded as high luminance (BlightHigh) and the value regarded as low luminance (BlightLow) are set such that the smaller the Bv value, the easier it is to determine that a high-luminance subject is included.

Each determination parameter is set as follows according to the Bv value, for example.
[1] When the Bv value ≥ 0: Since it is not determined that a high-luminance subject is included, no determination parameter is set.
[2] When 0> Bv value ≥ -2
NumHighLowPixs = 70% of the total number of pixels in the area (rounded off if less than 1 pixel)
NumHightPixs = 1% of the total number of pixels in the area (rounded off to less than 1 pixel)
Yp0 = 240
MM0 = 160
BlightHigh = 235
BlightLow = 100
[3] -2> Bv value ≥ -3
NumHighLowPixs = 60% of the total number of pixels in the area (rounded off if less than 1 pixel)
NumHightPixs = 0.9% of the total number of pixels in the area (rounded off if less than 1 pixel)
Yp0 = 240
MM0 = 170
BlightHigh = 230
BlightLow = 80
[4] When -3> Bv value
NumHighLowPixs = 50% of the total number of pixels in the area (rounded off if less than 1 pixel)
NumHightPixs = 0.8% of the total number of pixels in the area (rounded off if less than 1 pixel)
Yp0 = 240
MM0 = 180
BlightHigh = 225
BlightLow = 60

  However, these are numerical values when the range of the luminance value is 0 to 255. Even a combination different from these may be set as long as it is easier to determine that the darker the high-luminance subject is included in the region.

  In S302, a histogram within the corresponding frame is acquired, and the process proceeds to S303. The histogram mentioned here is a process of measuring the luminance value for each pixel and calculating how many pixels of each luminance value exist for the pixels in the frame. For example, when the luminance value after A / D conversion is 0 to 255, this is a process for determining how many pixels there are in each of the luminance values 0 to 255. Further, the area of the corresponding frame is set to the same area as the distance measuring area of S501 in FIG.

  In S303, the number of pixels having a luminance value lower than the predetermined luminance value (BlightLow) (NumBlightLow) is calculated from the histogram acquired in S301, and the process proceeds to S304. In S304, the number of pixels having a luminance value higher than a predetermined luminance value (BrightHigh) is calculated from the histogram acquired in S301, and the process proceeds to S305. In S305, a histogram Yp and a histogram MM described later are calculated, and the process proceeds to S306. In S306, it is checked whether or not the sum of NumBlightLow and NumBrightHigh is larger than NumHighLowPixs. If it is larger, the process proceeds to S307, and if not, the process proceeds to S311. In S307, it is checked whether NumBrightHigh is larger than NumHighPixs. If it is larger, the process proceeds to S308, and if not, the process proceeds to S311.

  In S308, it is checked whether or not the histogram Yp calculated in S305 is larger than the predetermined value Yp0. If it is larger, the process proceeds to S309, and if not, the process proceeds to S311. In S309, it is checked whether or not the histogram MM calculated in S305 is larger than the predetermined value MM0. If so, the process proceeds to S310, and if not, the process proceeds to S311. In S310, it is determined that a high-luminance subject is included in the corresponding frame, the present flow is ended, and the process proceeds to S204. In S311, it is determined that the high-luminance subject is not included in the corresponding frame, and this flow is ended, and the process proceeds to S204.

  FIG. 4 is a flowchart for explaining the calculation of the histogram Yp and the histogram MM in S305 in FIG. First, in S401, the total number of pixels (NumHistPixls) in the corresponding frame for which the histogram was acquired in S302 is calculated, and the process proceeds to S402. In S402, ThrNumHist, which is a threshold value of the number of pixels regarded as valid, is calculated by taking the product of NumHistPixls calculated in S401 and the ratio (ratio) ThrRatio of the number of pixels regarded as valid, and the process proceeds to S403. Here, the threshold value of the number of pixels regarded as valid is a threshold value for excluding the luminance value that does not exist originally such as noise, and the luminance value of the number of pixels less than this threshold value is described later. The histogram Yp and the histogram MM are not used for calculation.

  In S403, the brightness value is initialized to 0, and it is determined whether the brightness value is an effective brightness value from brightness value 0, and the process proceeds to S404. In S404, it is checked whether or not the number of pixels of the luminance value to be determined is larger than hrNumHist. If so, the process proceeds to S405, and if not, the process proceeds to S407. In S405, the luminance value determined in S404 is regarded as an effective luminance value, and the process proceeds to S407. In S407, it is checked whether or not the luminance value is 255. If so, the process proceeds to S408, and if not, the process proceeds to S406. In S406, the luminance value to be determined is incremented, and the process proceeds to S404. By repeating the processing of S404 to S407 while updating the luminance value, it is possible to determine whether or not the luminance value is an effective luminance value in all of the luminance values 0 to 255.

  In S408, the maximum and minimum effective luminance values are calculated, and the process proceeds to S409. In S409, the maximum effective luminance value is set as the histogram Yp, and the process proceeds to S410. In S410, the difference between the maximum value and the minimum value of the effective luminance value is set as the histogram MM, and this flow is finished, and the process proceeds to S306.

  FIG. 5 is a flowchart for explaining the safety MF operation in S206 in FIG. First, in S501, a distance measurement area is set as a predetermined area in the screen, and the process proceeds to S502. The predetermined area is set by, for example, one frame having a size of 18% of the screen at the center. In S502, it is checked whether or not the Bv value is BvThr1 or more. If so, the process proceeds to S504, and if not, the process proceeds to S503. Here, BvThr1 is set, for example, as BvThr1 = 0 so as to correspond to the determination parameter of the high-luminance subject in S301 described above. If the Bv value is equal to or greater than BvThr1, it is determined that there is no high-luminance subject in the distance measurement area, and the flow proceeds to a flow for performing normal safety MF.

  In S503, it is checked whether or not there is a high-luminance subject (that is, the determination result in S203) within the corresponding frame (the same area as the distance measurement area set in S501) for which the high-luminance subject has been determined in S203. If it is determined that it exists, the process proceeds to S507, and if not, the process proceeds to S504. In S504, normal safety MF setting 1 is performed, and the process proceeds to S505.

  Here, as setting items of the safety MF, there are a band of a band pass filter (BPF) when calculating a scan interval, the number of scan points, and a focus evaluation value. The normal safety MF setting 1 is set, for example, by scanning interval = 2.3 depth, number of scanning points = 5 points, BPF band = high range or low range (high range when brighter than a predetermined brightness, low range when dark) Area).

  This is because when the subject is dark, the S / N deteriorates and the noise component increases, so the BPF setting in the low frequency band is performed in order to remove the high frequency band component due to noise. Since it is the MF mode, the scan interval and the number of scan points are determined so that the focus fluctuation due to the assist of focusing is not conspicuous in the live image as much as possible.

  In S505, after performing an AF scan described later, the process proceeds to S506. In S506, after performing the normal focus determination described later, the process proceeds to S512. In S507, it is checked whether or not the Bv value is less than BvThr2. If so, the process proceeds to S509, and if not, the process proceeds to S508. Here, BvThr2 is set to BvThr2 = −3, for example, so as to correspond to the determination parameter of the high-luminance subject in S301 described above. If the Bv value is greater than or equal to BvThr2, it is determined that the high-brightness subject and the illuminated normal subject are mixed, and the flow proceeds to a flow for performing safety MF suitable for the situation. If the Bv value is less than BvThr2 Then, it is determined that there is a high-luminance subject in the dark, and the flow proceeds to a flow for performing safety MF most suitable for the high-luminance subject.

  In S508, it is determined that the high-brightness subject and the illuminated normal subject are mixed, and after performing safety MF setting 2 suitable for the situation, the process proceeds to S510. Here, the setting method of the high brightness safety MF setting 2 is, for example, scan interval = 2.3 depth, number of scan points = 5, and BPF band = low range. In S509, it is determined that there is a high-luminance subject in the dark, and after performing safety MF setting 3 most suitable for the high-luminance subject, the process proceeds to S510. Here, the setting method of the high brightness safety MF setting 3 is, for example, scan interval = 4.6 depth, number of scan points = 5, and BPF band = high range.

  Next, the reason for performing this setting will be described. As described in the background art described above, in the case of a high-luminance subject, the focus evaluation value in the low band does not become maximum at the focus position, but has a valley-like shape as shown in FIG. Further, since the luminance signal (Yi) has the same shape as shown in FIG. 10, the shape like a valley is slightly improved by normalizing the low-frequency focus evaluation value with Yi. As a normalization method of Yi, for example, a method of dividing each by Yi acquired at the same position as the focus lens position from which the focus evaluation value is acquired is used. However, even if the low-frequency focus evaluation value is normalized by Yi, the focus position cannot be detected so as to be detected.

  On the other hand, the high-frequency focus evaluation value tends to be less likely to have a valley shape at the focus position as shown in FIG. 11A than the low-frequency focus evaluation value. This is presumed to be due to the fact that the luminance value of the subject image becomes discontinuous due to saturation of the luminance value, thereby generating a high-frequency component, and this high-frequency component increases near the focus position. When this high-frequency focus evaluation value is further normalized by Yi, the maximum is obtained at the peak position as shown in FIG. Further, in the case of a high-luminance subject, the peak shape of the focus evaluation value is broader than that of a normal subject, so that it is easier to determine the peak shape by extending it beyond the normal scan range. Therefore, the setting is wider than the normal scan interval.

  In S510, after performing an AF scan described later, the process proceeds to S511. In S511, after performing a high-luminance subject focus determination described later, the process proceeds to S512. In S512, the focus lens is moved to the photographing position determined in S506 or S511, which will be described later, the present flow is ended, and the process proceeds to S208.

  FIG. 6 is a flowchart for explaining the AF scanning in S505 and S510 in FIG. In S601, the current focus position is stored, and the process proceeds to S602. The focus position stored here is necessary when used for a shooting position to be described later. In S602, an AF scan range is calculated and set from the current focus position, the scan interval and the number of scan points set in any of S504, S508, and S509 described above, and the process proceeds to S603. In S603, the focus lens is moved to the AF scan start position which is the end of the AF scan range set in S602, and the process proceeds to S604.

  Here, the end may be either a far end or a near end. In S604, the focus lens starts to move in a predetermined direction at a predetermined speed, and the process proceeds to S605. Here, the predetermined speed is calculated from the current frame rate and the scan interval. The predetermined direction is the direction in which the AF scan range set in S602 is scanned. In S605, the focus evaluation value in the distance measurement area set in S501 is acquired, and the process proceeds to S606. Here, in the calculation of the focus evaluation value, two outputs, that is, an output using a high-frequency BPF (TES) and an output using a low-frequency BPF (FES) are output, and are set in S504, S508, and S509. Accordingly, which focus evaluation value is used is determined.

  In the BPF setting, for example, a BPF coefficient is set such that TES is 50% of the Nyquist frequency and FES is 20% of the Nyquist frequency. In S606, the current position of the focus lens is acquired, and the process proceeds to S607. In S607, it is checked whether or not the current focus lens position acquired in S606 is within the scan range set in S602. If it is within the scan range, the process proceeds to S605, and if not, the process proceeds to S608. Here, the series of operations from S605 to S607 is performed for a time corresponding to one frame at the current frame rate.

  In addition, the focus evaluation value acquired in S605 and the lens position acquired in S606 are associated with each other and used in the calculation of the peak position of the focus evaluation value in S709 and S808 described later. At this time, since the focus lens is driven during the acquisition of the focus evaluation value, the position of the focus lens at the center timing of the exposure time is calculated and associated with the focus evaluation value. In S608, the focus lens is stopped to end the present flow, and the process proceeds to S506 or S511.

  FIG. 7 is a flowchart for explaining the normal focus determination in S506 in FIG. First, in S701, the focus evaluation value is normalized with the luminance signal (Yi), and the process proceeds to S702. In S702, the maximum value (Max) and the minimum value (Min) of the focus evaluation value are calculated, and the process proceeds to S703. In S703, the scan point (MaxPoint) that maximizes the focus evaluation value is calculated, and the process proceeds to S704. In S704, the length L and the slope SL of the inclined portion for judging the shape of the mountain are obtained from the scan point and the focus evaluation value, SL / L is calculated, and the process proceeds to S705.

  In S705, it is determined whether the mountain shape stops climbing on the near side. It is determined that the near-end climbing stop is at the near end in the predetermined range where the scan point with the maximum focus evaluation value is scanned, and the focus evaluation value at the near end scan point and the near end. This is a case where the difference in the focus evaluation value at the scan point from infinity by one point from the scan point is a predetermined value or more. If it is determined that the climb to the closest side is stopped, the process proceeds to S713, and if not, the process proceeds to S706. In S706, it is determined whether the mountain shape stops climbing to infinity.

  It is determined that the climb to the infinity side is stopped at the infinity end in the predetermined range where the scan point that has the maximum focus evaluation value is scanned, and the value of the focus evaluation value at the infinity end scan point And the difference in the focus evaluation value at the scan point from the closest end by one point from the infinity end scan point is a predetermined value or more. If it is determined that the climb to the infinity side is stopped, the process proceeds to S711, otherwise the process proceeds to S707.

  In S707, the length L of the portion inclined at a certain inclination or more is a predetermined value or more, the average value SL / L of the inclination of the inclined portion is a predetermined value or more, and the focus evaluation value If the difference between the maximum value (Max) and the minimum value (Min) is greater than or equal to the predetermined value, the process proceeds to S708, and if not, the process proceeds to S711. In S708, the obtained focus evaluation value is mountain-shaped, the subject has contrast, and focus adjustment is possible. Therefore, the determination result is determined as ◯, and the process proceeds to S709.

  In S711, since the obtained focus evaluation value is not mountain-shaped, the subject has no contrast, and focus adjustment is impossible, the determination result is set as x determination and the process proceeds to S712. Although the focus evaluation value obtained in S713 is not mountain-shaped, it is in a state where it continues to climb in the near-end direction, and there is a possibility that a subject peak exists on the near side, so the determination result Is determined as Δ and the process proceeds to S714.

  Hereinafter, details of how to determine the peak shape will be described with reference to FIG. The focus evaluation value takes a mountain shape as shown in FIG. 9 when the horizontal axis represents the focus lens position and the vertical axis represents the focus evaluation value, except in the case of distance competition. Therefore, by determining the shape of the mountain from the difference between the maximum value and the minimum value of the focus evaluation value, the length of the inclined portion with a slope equal to or greater than a certain value (SlopeThr), and the slope of the inclined portion, In-focus determination can be performed.

The determination result in the in-focus determination is output by ○ determination, × determination, and Δ determination as shown below.
○ Judgment: The subject has sufficient contrast and the subject exists at a distance within the scanned distance range.
X: The subject contrast is insufficient, or the subject is located at a distance outside the scanned distance range.

  Further, in the x determination, a case where the subject is located outside the scanned distance range in the near side direction is determined as Δ determination.

  The length L of the inclined portion and the slope SL / L of the inclined portion for judging the mountain shape will be described with reference to FIG.

  Points that are recognized to be inclined from the top of the mountain (point A) are defined as points D and E, and the width between points D and E is defined as the width L of the mountain. The range in which the inclination is recognized to be continued is a range in which a scan point whose focus evaluation value has decreased by a predetermined amount (SlopeThr) or more continues from the point A. A scan point is a point at which a focus evaluation value is acquired while moving a focus lens continuously and moving from a scan start point to a scan end point.

  The sum SL1 + SL2 of the difference SL1 between the focus evaluation values of the points A and D and the difference SL2 of the focus evaluation values between the points A and E is defined as SL. The peak shape determination is performed as described above.

  In S709, the peak position is calculated and the process proceeds to S710. In S710, the peak position calculated in S709 is set as the shooting position, the present flow is terminated, and the process proceeds to S512. In S712, the focus lens position (that is, the original focus lens position) stored in S601 is set as a shooting position, the present flow is terminated, and the process proceeds to S512. In step S714, the position where the climbing stops is set as the shooting position, the present flow is terminated, and the process proceeds to step S512.

  FIG. 8 is a flowchart for explaining the high-luminance subject in-focus determination in S511 in FIG. In S801, the focus evaluation value is normalized with the luminance signal (Yi), and the process proceeds to S802. In S802, the maximum value (Max) and the minimum value (Min) of the focus evaluation value are calculated, and the process proceeds to S703. In step S803, the scan point (MaxPoint) that maximizes the focus evaluation value is calculated, and the process advances to step S804. In S804, the length L and the slope SL of the inclined portion for judging the shape of the mountain are obtained from the scan point and the focus evaluation value, SL / L is calculated, and the process proceeds to S805.

  In step S805, it is determined whether the mountain shape stops climbing on the near side. It is determined that the near-end climbing stop is at the near end in the predetermined range where the scan point with the maximum focus evaluation value is scanned, and the focus evaluation value at the near end scan point and the near end. This is a case where the difference in the focus evaluation value at the scan point from infinity by one point from the scan point is a predetermined value or more. If it is determined that the climb to the closest side is stopped, the process proceeds to S812, and if not, the process proceeds to S806.

  In S806, it is determined whether the mountain shape stops climbing toward infinity. It is determined that the climb to the infinity side is stopped at the infinity end in the predetermined range where the scan point that has the maximum focus evaluation value is scanned, and the value of the focus evaluation value at the infinity end scan point And the difference in the focus evaluation value at the scan point from the closest end by one point from the infinity end scan point is a predetermined value or more. If it is determined that the climb to the infinity side is stopped, the process proceeds to S812, and if not, the process proceeds to S807.

  In S807, the length L of the portion inclined at a certain inclination or more is a predetermined value or more, the average value SL / L of the inclination of the inclined portion is a predetermined value or more, and the focus evaluation value If the difference between the maximum value (Max) and the minimum value (Min) is greater than or equal to a predetermined value, the process proceeds to S808, and if not, the process proceeds to S812. In S808, the peak position is detected and the process proceeds to S809. In S809, it is determined whether or not the peak position is within the normal safety MF scan range. If it is within the range, the process proceeds to S810, and if not, the process proceeds to S812.

  In S810, the focus evaluation value obtained is mountain-shaped, the subject has contrast, and focus adjustment is possible. Therefore, the determination result is set as ◯, and the process proceeds to S811. In S812, since the obtained focus evaluation value is not mountain-shaped, the subject has no contrast, and focus adjustment is impossible, the determination result is X determination and the process proceeds to S813. Here, in S805, the focus determination for the case where the vehicle is in the state of continuing to climb in the near end direction will be described. In the focus determination for a normal subject, since the subject peak may exist on the closer side, the determination result is △ determination, but for a high-luminance subject, there is a possibility of erroneous distance measurement. Yes.

  Even if it is determined that the peak shape can be focused in S807, the high-luminance subject is wider than the normal safety MF scan range, and therefore, if the distance is erroneously measured outside the normal safety MF scan range, Since the focus is deviated from the normal safety MF, x determination is made.

  In the present invention, a focus evaluation value when a subject with a brightness higher than a predetermined value exists in the focus detection area and a focus evaluation when a subject with a brightness higher than the predetermined value does not exist in the focus detection area. The values are different.

  In the present invention, focus evaluation values are sampled when there is an object with a brightness higher than a predetermined value in the focus detection area and when there is no object with a brightness higher than the predetermined value in the focus detection area. At least one of the focus determination method using the distance and the moving range of the focus lens that moves by the automatic focus adjustment by the execution means and the focus evaluation value is different.

  In the present invention, when an object with a brightness higher than a predetermined value exists in the focus detection area, a frequency band higher than that when no object with a brightness higher than the predetermined value exists in the focus detection area. Automatic focus adjustment is performed using the focus evaluation value.

  In the present invention, when a subject with a brightness higher than the predetermined value exists in the focus detection area, the focus evaluation value is higher than when a subject with a brightness higher than the predetermined value does not exist in the focus detection area. The movement range of the focus lens is expanded by the sampling interval and automatic focus adjustment by the execution means.

  In the present invention, when it is determined that there is no subject with a brightness higher than the predetermined value in the focus detection area, the execution means is the end of the focus evaluation value that has stopped climbing at the end within the moving range of the focus lens. When it is determined that a subject with a brightness higher than the predetermined value exists in the focus detection area using the focus determination method with the position as the focus position, the focus evaluation value at the end within the moving range of the focus lens When the camera stops climbing, an in-focus determination method is used in which the position of the focus lens moved by the manual focus is the in-focus position.

  In the present invention, the execution means determines the focus evaluation value even if the peak position of the focus evaluation value can be detected when it is determined that there is an object with a brightness higher than the predetermined value in the focus detection area. Focus moved by manual focus when the peak position is outside the focus lens movement range set when it is determined that there is no subject with brightness higher than the specified value in the focus detection area An in-focus determination method using the lens position as the in-focus position is used.

  In the present invention, the automatic focus adjustment uses a focus evaluation value obtained by normalizing the focus evaluation value with a luminance signal.

  In the present invention, when the execution means is darker than the predetermined brightness value, the focus evaluation value when a subject having a brightness higher than the predetermined value exists in the focus detection area and the predetermined value in the focus detection area. The focus evaluation values are different when no subject with high brightness exists.

  In the present invention, when the execution unit is darker than the first luminance value, there is a case where an object having a luminance higher than the predetermined value exists in the focus detection region and a luminance higher than the predetermined value in the focus detection region. When there is no subject, the focus evaluation value sampling interval, the moving range of the focus lens that moves by the automatic focus adjustment by the execution means, and the focus determination method using the focus evaluation value are all different.

  In the present invention, the execution means has a predetermined value in the focus detection area when the luminance value at the time of instruction by the instruction means is between the first luminance value and the second luminance value brighter than the first luminance value. Only the focus determination method using the focus evaluation value is different between a case where a subject with higher brightness exists and a case where a subject with higher brightness than a predetermined value does not exist in the focus detection area.

(Computer description)
Although the present invention has been described in detail based on preferred embodiments thereof, 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. included. A part of the above-described embodiments may be appropriately combined. Also, when a software program that realizes the functions of the above-described embodiments is supplied from a recording medium directly to a system or apparatus having a computer that can execute the program using wired / wireless communication, and the program is executed Are also included in the present invention. Accordingly, the program code itself supplied and installed in the computer in order to implement the functional processing of the present invention by the computer also realizes the present invention. That is, the computer program itself for realizing the functional processing of the present invention is also included in the present invention.

  In this case, the program may be in any form as long as it has a program function, such as an object code, a program executed by an interpreter, or script data supplied to the OS. As a recording medium for supplying the program, for example, a magnetic recording medium such as a hard disk or a magnetic tape, an optical / magneto-optical storage medium, or a nonvolatile semiconductor memory may be used. As a program supply method, a computer program that forms the present invention is stored in a server on a computer network, and a connected client computer downloads and programs the computer program.

  A mobile phone as an embodiment of the present invention is also applicable.

  The mobile phone according to the present embodiment has an electronic mail function, an Internet connection function, an image shooting and playback function, etc. in addition to a voice call function.

  The form of FIG. 5 of the present invention can be applied to image capturing.

  The communication unit of the mobile phone communicates audio data and image data with other telephones by a communication method according to a communication carrier contracted by the user. The voice processing unit converts voice data from the microphone into a format suitable for outgoing call and sends the voice data to the communication unit during a voice call.

DESCRIPTION OF SYMBOLS 101 Shooting lens 102 Aperture and shutter 103 AE processing unit 104 Focus lens 105 Motor 106 AF processing unit 107 Image sensor 108 A / D conversion unit 109 Image processing unit 110 Format conversion unit 111 DRAM
112 Image recording unit 113 System control unit 114 VRAM
115 Image Display 116 Operation Unit 117 Shooting Mode Switch 118 Main Switch 119 Shooting Standby Switch 120 Shooting Switch

Claims (7)

An image sensor for imaging a subject image formed by a photographing optical system including a focus lens;
Manual focus means capable of moving the focus lens based on manual operation ;
Focus evaluation indicating the contrast of the focus detection area based on the image data output from the image sensor with reference to the position of the focus lens moved by the manual focus after the manual focus is performed by the manual focus means Automatic focus adjustment means for calculating a value and adjusting the position of the focus lens according to the focus evaluation value;
Determining means for determining whether or not there is an object having a brightness higher than a predetermined value in the focus detection area;
When it is determined that an object with a brightness higher than a predetermined value exists in the focus detection area, the automatic focus adjustment unit includes an object with a brightness higher than a predetermined value in the focus detection area. An imaging apparatus characterized by expanding at least one of a sampling interval of the focus evaluation value and a moving range of the focus lens when sampling the focus evaluation value, compared to a case where it is determined that the focus evaluation value is not . When it is determined that an object with a brightness higher than a predetermined value exists in the focus detection area, the automatic focus adjustment unit includes an object with a brightness higher than a predetermined value in the focus detection area. The imaging apparatus according to claim 1, wherein the position of the focus lens is adjusted using a focus evaluation value in a higher frequency band than when it is determined that the focus lens is not. A case where it is determined that there is no high luminance of the object than the predetermined value before Symbol focus detection area, when the focus evaluation value has stopped climbing at the end of the moving range of the focus lens , Using a focus determination method in which the position of the end within the movement range of the focus lens is a focus position,
Even when the subject brightness higher than a predetermined value in the focus detection area is determined to be present, when the focus evaluation value at the end in the moving range of the focus lens is stopped climbing, the imaging apparatus according to claim 1 or 2, characterized in that a focus determination method of the focus position of the position of the focus lens is moved by the manual focusing. If the subject brightness higher than a predetermined value in the focus detection area is determined to be present, the even focus evaluation value can be detected focus lens position at which the peak, the focus evaluation value peak become when the focus lens position was outside the range of the moving range of the focus lens to be set when the focus detection luminance higher than a predetermined value in a region subject is determined not to exist, the manual the imaging apparatus according to claim 1 or 2, characterized in that a focus determination method of the position of the focus lens is moved in the focus and in-focus position. The automatic focusing is the focus evaluation value in accordance with the focus evaluation value obtained by normalizing the luminance signal, as claimed in any one of claims 1 to 4, characterized in that to adjust the position of the focus lens Imaging device. The determination means determines whether the luminance of the subject image formed by the photographing optical system is between a first luminance value and a second luminance value brighter than the first luminance value, or by the photographing optical system. Further determining whether the brightness of the formed subject image is less than or equal to the first brightness value;
The automatic focus adjustment unit has a luminance higher than a predetermined value in the focus detection area when it is determined that the luminance of the subject image formed by the photographing optical system is equal to or lower than the first luminance value. The at least one of a sampling interval of the focus evaluation value and a moving range of the focus lens when sampling the focus evaluation value is wider than a case where it is determined that a subject does not exist. The imaging apparatus according to 1. A control method for an image pickup apparatus including an image pickup device for picking up a subject image formed by a photographing optical system including a focus lens,
A manual focus step capable of moving the focus lens based on a manual operation;
Focus evaluation indicating the contrast of the focus detection area based on the image data output from the image sensor with reference to the position of the focus lens moved by the manual focus after the manual focus is performed by the manual focus step An automatic focus adjustment step of calculating a value and adjusting the position of the focus lens according to the focus evaluation value;
A determination step of determining whether or not there is an object with a brightness higher than a predetermined value in the focus detection area,
In the automatic focus adjustment step, when it is determined that an object with a brightness higher than a predetermined value exists in the focus detection area, an object with a brightness higher than the predetermined value exists in the focus detection area. The imaging apparatus is controlled to widen at least one of a sampling interval of the focus evaluation value and a moving range of the focus lens when sampling the focus evaluation value, compared to a case where it is determined that the focus evaluation value is not detected. Control method.

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