JP4881113B2 - IMAGING DEVICE, IMAGING DEVICE CONTROL METHOD, PROGRAM, AND STORAGE MEDIUM - Google Patents

Description

  The present invention relates to an imaging apparatus having a feature in an automatic focusing technique, an imaging apparatus control method, a program, and a storage medium.

  An imaging apparatus such as a digital camera or a digital video camera is equipped with an automatic focus detection processing technique for performing a focusing operation using a high-frequency component of a luminance signal obtained from a solid-state imaging device. In this automatic focus detection process, the lens position with the highest contrast is detected as the in-focus point by integrating the high-frequency component of the luminance signal in the focus detection area set in the imaging screen while moving the focus lens. To do.

  In the image pickup apparatus in the prior art, for this automatic focus detection process, the subject light is separated into a plurality of types of color signal components, and after combining at an arbitrary ratio according to the focal length and aperture of the lens, a high frequency component is detected, The focus is adjusted by integrating within the focus detection area. A proposal of such a technique for automatic focus detection processing is disclosed in Patent Document 1, for example.

In addition, a specific focus detection area is selected in advance from a plurality of focus detection areas in the imaging screen. Then, the focus detection value obtained in the specific focus detection area is corrected in accordance with the color signal information of the subject in the focus detection area and the position of the focus detection area in the imaging screen, and the in-focus position There are also proposals to adjust this.
Japanese Patent Laid-Open No. 2001-141988

  However, in the conventional example disclosed in Patent Document 1, the composition ratio of a plurality of color signal components is not changed according to the position of the focus detection area and the color signal information in the focus detection area. Therefore, when applied to an imaging device of a multipoint focus detection method, only an evaluation value that is not worthy of focusing is obtained from the focus detection area in the peripheral portion compared to the central portion of the imaging screen due to the influence of the chromatic aberration of magnification of the lens. There was no problem.

  Further, in the conventional example, with respect to a focus detection value of a specific focus detection area detected as a white light signal, control for moving the lens position with reference to a correction value corresponding to the position of the focus detection area and the color signal information is performed. Do. For this reason, there is a problem in that focus detection values from a plurality of focus detection areas cannot be compared automatically under the same conditions to automatically determine a focus position within the imaging screen.

  The present invention has been made in view of such problems, and an object of the present invention is to propose an imaging method that realizes further improvement in focusing accuracy.

In order to achieve the above object, an imaging apparatus according to an embodiment of the present invention provides:
Imaging means for capturing a subject image and outputting image data ;
Separating means for separating the image data obtained from the imaging means into a plurality of color signal components;
High frequency component detection means for detecting high frequency components for each of the plurality of color signal components output from the separation means;
Relates focus detection areas set in a plurality of positions in the imaging screen of the imaging means, and the focus detection area position information detecting means for the position in the imaging screen of each focus detection area is calculated to information I Table,
Color signal information detecting means for detecting color signal information for each focus detection area;
For each of the focus detecting area, on the basis of the position information representing the said color signal information in the imaging screen, synthesizing each of the high-frequency component output from the high frequency component detection means, generating a focus detection evaluation value And a focus detection evaluation value generating means.

In order to achieve the above object, a method for controlling an imaging apparatus according to another embodiment of the present invention includes:
A separation step of separating the image data output from the imaging means into a plurality of color signal components;
A high-frequency component detection step for detecting a high-frequency component for each of the plurality of color signal components output in the separation step;
A plurality of relates focus detection areas set in position, the focus detecting area position information detection step of the position in the imaging screen of each focus detection area is calculated to information I table in the imaging screen in the image pickup means,
A color signal information detection step of detecting color signal information for each focus detection region;
For each of the focus detecting area, on the basis of the position information representing the said color signal information in the imaging screen, synthesizing each of the high-frequency component output from the high-frequency component detecting step, generating a focus detection evaluation value And a focus detection evaluation value generation step.

  According to the present invention, it is possible to improve focusing accuracy.

<Embodiment 1>
Hereinafter, according to the drawings, the configuration and operation of an imaging apparatus according to an embodiment of the present invention will be sequentially described. FIG. 1 is a block diagram illustrating a configuration of an imaging apparatus that is Embodiment 1 of the present invention. In the imaging apparatus according to the embodiment of the present invention, multipoint focus detection type autofocus processing (hereinafter referred to as multipoint AF) is performed.

  In FIG. 1, 1 is an optical system including a lens and a diaphragm mechanism, 2 is a solid-state imaging device in which primary color filters are arranged in a Bayer shape, and 3 is an analog front end unit (hereinafter referred to as AFE) including a CDS circuit and an A / D conversion circuit. Show).

  Reference numeral 5 denotes a timing signal generating circuit for generating a clock signal or the like for operating the solid-state imaging device 2, AFE 3, etc., and 4 denotes a driving circuit for the optical system 1 and the solid-state imaging device 2. Reference numeral 7 denotes a camera signal processing circuit that generates a luminance signal and a color difference signal from image data (indicated as RAW in the drawing) obtained from the AFE 3.

  Further, 8 is an AF evaluation value generation circuit for generating an AF evaluation value for automatic focus adjustment processing (hereinafter referred to as AF processing), 9 is an image memory for storing image data, and 10 is image data subjected to camera signal processing. Is a coding compression processing circuit for performing coding compression processing.

  Reference numeral 12 denotes a recording medium that records image data and is removable from the imaging device. Reference numeral 11 denotes a recording processing circuit that records encoded and compressed image data on the recording medium 12. Reference numeral 14 denotes image data that has undergone camera signal processing. An image display device for display.

  Reference numeral 13 denotes a display control circuit for displaying image data on the image display device 14, reference numeral 6 denotes a system control unit for controlling the entire imaging apparatus, and reference numeral 15 denotes communication between the system control unit 6 and each circuit block in the imaging apparatus. It is a bus to perform. Reference numeral 16 denotes a non-volatile memory (ROM) for storing a control program executed by the system control unit 6 and control data such as parameters and tables used when executing the program. Reference numeral 17 denotes a volatile memory (RAM) that transfers and stores the program and control data stored in the nonvolatile memory 16 and is used when the system control unit 6 controls the imaging apparatus.

  Hereinafter, a photographing operation in the imaging apparatus configured as described above will be described. Prior to the shooting operation, necessary programs, control data, and correction data are transferred from the ROM 16 to the volatile memory 17 and stored at the start of the operation of the system control unit 6 such as when the imaging apparatus is turned on. .

  These programs and data are used when the system control unit 6 controls the imaging apparatus. Further, if necessary, an additional program or data is transferred from the nonvolatile memory 16 to the volatile memory 17, or the system control unit 6 directly reads and uses the data in the nonvolatile memory 16.

  First, the drive circuit 4 drives the optical system 4 including a diaphragm mechanism and a lens by a control signal from the system control unit 6 to form a subject image set to an appropriate brightness on the solid-state imaging device 2. .

  The solid-state imaging device 2 is driven based on an operation clock pulse generated by the timing signal generation circuit 5 controlled by the system control unit 6, converts the subject image into an electrical signal by photoelectric conversion, and outputs it as an analog image signal. .

  The analog image signal output from the solid-state imaging device 2 is subjected to operation pulse generated by the timing signal generation circuit 5 controlled by the system control unit 6 to remove clock synchronous noise by a CDS circuit (not shown) provided in the AFE 3. To do. Thereafter, it is converted into a digital image signal by an A / D conversion circuit (not shown) inside the AFE 3.

  In the camera signal processing circuit 7 controlled by the system control unit 6, the RGB separation processing circuit 70 separates the digital image signal output from the AFE 3 into R, G, and B color signals, and then achieves white balance. Further, the YC matrix processing circuit 71 generates a low-frequency luminance signal YL and color difference signals CR and CB from the RGB signal after white balance. Further, the BPF 72 extracts the high-frequency luminance signal YH from the RAW output from the AFE 3, and the APC processing circuit 73 adds the high-frequency luminance signal YH to the low-frequency luminance signal YL so that the contour-compensated luminance signal is obtained. Y is output.

  The R, G, and B signals after the white balance processing output from the RGB separation processing circuit 70 are also input to the AF evaluation value generation circuit 8.

  The image memory 9 is used for temporarily storing a digital image signal during signal processing or for storing image data which is a digital image signal subjected to signal processing. Hereinafter, the digital image signal will be described as image data.

  The encoding / compression processing circuit 10 is controlled by the system control unit 6 and encodes and compresses the image data signal-processed by the camera signal processing circuit 7 by a method compliant with the video signal standard. The encoded and compressed image data is converted into a data format suitable for the recording medium 12 by the recording processing circuit 11 controlled by the system control unit 6 and recorded on the recording medium 12.

  The image data output from the camera signal processing circuit 7 is converted into a signal suitable for the image display device 14 (for example, an NTSC analog signal) by the display control circuit 13 and displayed on the image display device 14.

  Here, the system control unit 15 is connected to the drive circuit 4, the timing signal generation circuit 5, the camera signal processing circuit 7, the AF evaluation value generation circuit 8, the encoding / compression processing circuit 10, the display control circuit 13, via the bus 15. The recording processing circuit 11 and the like are controlled. Information such as control parameters necessary for each signal processing circuit and a program for controlling each signal processing circuit is read from the ROM 16 connected to the system control unit 6.

  In FIG. 1, 8 is an AF evaluation value generation circuit. Hereinafter, the configuration of the AF evaluation value generation circuit 8 will be described.

  Reference numerals 800, 801, and 802 denote bandpass filter circuits (hereinafter referred to as BPF) for detecting high-frequency components Rh, Gh, and Bh for the R, G, and B signals output from the camera signal processing circuit 7, respectively. .) Reference numerals 803, 804, and 805 denote integration circuits that integrate the RGB signals output from the camera signal processing circuit 7 for each focus detection area and normalize them by the size of the focus detection area.

  Reference numeral 806 denotes a RAM for temporarily holding a signal being processed during the AF evaluation value generation process, and is referred to as an AF-RAM here. Reference numeral 807 denotes a saturation detection circuit for obtaining an average saturation C in the focus detection region from the RGB signal integrated values Rav, Gav, and Bav output from the camera signal processing circuit 7. Reference numeral 808 denotes a tint detection circuit that compares the integrated values Rav, Gav, and Bav and outputs a flag “max_col” indicating whether the color in the focus detection region is biased to R, G, or B. is there.

  Further, reference numeral 809 denotes the high frequency of the R, G, and B signals using the average saturation C in the focus detection area, the flag “max_col” of the tint detection circuit 808, and the focus detection area position information input from the system control unit 6. This is a synthesis ratio generation circuit that generates component synthesis ratios Kr, Kg, and Kb. Reference numeral 810 denotes an evaluation value synthesis circuit. The evaluation value synthesis circuit 810 uses the synthesis ratios Kr, Kg, and Kb that are the outputs of the synthesis ratio generation circuit 809 and uses the high-frequency components Rh, Gh, and R of the R, G, and B signals that are the outputs of the bandpass filter circuits 800 to 802. Synthesize Bh. Then, a luminance signal “AF_Y” for AF evaluation is generated.

  811 is an integration circuit that integrates the luminance signal “AF_Y”, which is the output of the evaluation value synthesis circuit 810, for all the pixels in the focus detection area, and outputs the final AF evaluation value “AF_Y_av” in the focus detection area. is there. Reference numeral 812 denotes an image memory interface (denoted as an image memory I / F) that communicates image data with the image memory 9.

  Next, the operation of the AF evaluation value generation processing circuit 8 will be described with reference to the flowchart of FIG.

  First, in step S201 after the start of processing, the system control unit 6 resets the value of a focus detection area counter (not shown) set in the RAM 17 or the like to zero. In step S202, the coordinates of the focus detection area specified by the focus detection area counter are read from the ROM 16 by the system control unit 6 and written into the RAM 17.

  In step S203, the RGB signal output from the camera signal processing circuit 7 is read. In step S <b> 204, the system control unit 6 compares the coordinates of the AF focus detection area written in the RAM 17 with the positions of the RGB signal pixel data read from the camera signal processing circuit 7. When the pixel data of the RGB signal is located within the focus detection area of the AF evaluation value, the process proceeds to step S205 and step S206. However, if this is not the case, the camera signal processing circuit 7 waits for input of pixel data of the RGB signal at the next position.

  In step S205, the RGB signals are integrated by the integration circuits 803, 804, and 805 for all the pixel data in the focus detection area. The respective integrated values Rav, Gav and Bav of the RGB signals are stored in the AF-RAM 806.

  In step S206, the bandpass filter circuits 800, 801 and 802 extract high frequency components Rh, Gh and Bh from the RGB signals and store them in the image memory 9 via the image memory I / F 812.

  In step S207, it is determined whether or not the processing in step S205 and step S206 has been performed for all pixel data in the focus detection area.

  If the processing in step S205 and step S206 has been completed for all the pixels in the focus detection area, the process proceeds to step S208, and if not, the process returns to step S203.

  In step S208, the RGB signal integrated values Rav, Gav, and Bav are read from the AF-RAM 806. After that, in step S209, the saturation detection circuit 807 obtains the average saturation C in the focus detection area by the calculation shown in Equation 1.

  The average saturation C in the focus detection area thus obtained is stored in the AF-RAM 806. In step S210, the color detection circuit 808 compares the RGB signals integrated values Rav, Gav, and Bav read from the AF-RAM 806. Then, a flag “max_col” indicating which color signal component of the RGB signal is most contained in the subject in the focus detection area is set.

  In step S210, when the integral value Rav of the R signal is the maximum among the integral values Rav, Gav, and Bav, the flag “max_col” = 0 is set. Further, when the integral value Gav of the G signal is maximum, the flag “max_col” = 1 is set, and when the integral value Bav of the B signal is maximum, the flag “max_col” = 2 is set. A flag “max_col” indicating the color within the focus detection area set as described above is stored in the AF-RAM 806.

  In step S211, the flag “max_col” indicating the average saturation C in the focus detection area and the color in the focus detection area is read from the AF-RAM 806. In step S212, the synthesis ratio generation circuit 809 calculates synthesis ratios Kr, Kg, and Kb for synthesizing the high-frequency components Rh, Gh, and Bh of the RGB signals. The operation of the composition ratio generation process 809 will be described in detail later.

  In step S213, the system control unit 6 reads the high-frequency components Rh, Gh, and Bh of the RGB signals stored in the image memory 9 one by one through the image memory I / F 812, and the evaluation value synthesis circuit Sent to 810. In step S214, the evaluation value synthesis circuit 810 synthesizes the high-frequency components Rh, Gh, and Bh of the RGB signal at a ratio of synthesis ratio Kr: Kg: Kb as shown in Equation 2 to obtain the brightness for AF evaluation. A signal “AF_Y” is calculated.

  In step S215, the integration circuit 811 integrates the luminance signal “AF_Y” output from the evaluation value synthesis circuit 810, and outputs an AF evaluation value “AF_Y_av”. The output AF evaluation value “AF_Y_av” is stored in the AF-RAM 806.

  In step S216, it is determined whether the luminance signal “AF_Y” has been integrated for all the pixel data in the focus detection area. If the integration process has been completed for all the pixel data in the focus detection area, the process proceeds to step S217. However, if not, the process returns to step S213.

  In step S217, the AF evaluation value “AF_Y_av”, which is the integral value of the luminance signal “AF_Y” output from the integration circuit 811, is stored in the AF-RAM 806. In step S218, the system control unit 6 increments the value of the focus detection area counter by one.

  In step S219, with reference to the value of the focus detection area counter, it is determined whether or not the integral value “AF_Y_av” of the luminance signal has been generated for all focus detection areas. If the generation of the AF evaluation value “AF_Y_av”, which is the integral value of the luminance signal, has been completed in all focus detection areas, the process proceeds to step S220. If not, the process returns to step S202.

  In step S <b> 220, the system control unit 6 reads the AF evaluation value “AF_Y_av” corresponding to each focus detection area from the AF-RAM 806 and stores it in the RAM 17. Through the series of operations described above, AF evaluation values corresponding to all focus detection areas are generated.

  Next, the flow of the synthesis ratio generation process in the synthesis ratio generation circuit 809 will be described with reference to the flowchart of FIG. In step S <b> 301, chromatic aberration information specific to the lens included in the optical system 1 is read from the ROM 16 by the system control unit 6 and loaded into the RAM 17.

  The chromatic aberration information unique to the lens is, for example, data represented by a graph as shown in FIG. 4 and represents the degree of lateral chromatic aberration according to the focal length and the position of the focus detection region. In FIG. 4, the horizontal axis is the distance D from the optical axis to the center of the focus detection area, and the vertical axis is the level of lateral chromatic aberration.

  In step S302, the system controller 6 calculates the focal length from the lens position. In step S303, the system control unit 6 calculates position information of each focus detection area. Further, in step S304, the system control unit 6 calculates the chromatic aberration of magnification corresponding to the focal length calculated in step S302 and the position information of the focus detection area calculated in step S303 from the chromatic aberration information specific to the lens loaded in the RAM 17. Read the level.

  In step S305, the system control unit 6 compares the magnification chromatic aberration level read in step S304 with the threshold value TH1 shown in FIG. If the degree of lateral chromatic aberration is smaller than the threshold value TH1, the process proceeds to step S306. In this case, since there is no adverse effect of chromatic aberration of magnification, the synthesis ratio of the high frequency components Rh, Gh, and Bh is set to, for example, Kr: Kg: Kb = 5: 9: 2 so as to obtain a synthesis ratio that matches the visibility characteristics. The process is terminated.

  On the other hand, when the degree of lateral chromatic aberration is greater than the threshold value TH1, the process proceeds to step S307. In step S307, the average saturation C of the focus detection area designated by the focus detection area counter is read from the AF-RAM 806 and compared with the threshold value TH2 shown in FIG.

  In this case, when the saturation C is smaller than the threshold value TH2, the process proceeds to step S308. In this case, the saturation in the focus detection region is regarded as an achromatic color, and the combined ratio of the high frequency components Rh, Gh, and Bh is set to Kr: Kg: Kb = 0 so that the influence of the color shift due to the chromatic aberration of magnification is not reflected in the focus detection value. : Set to 1: 0. On the other hand, when the saturation C is larger than the threshold value TH2 in the determination in step S307, it is regarded as not an achromatic color, and the process proceeds to step S309.

  In step S309, the flag “max_col” indicating the color in the focus detection area is read from the AF-RAM 806. If the value of the flag “max_col” is 0, that is, if the integral value Rv of R is the largest in the focus detection area, the combined ratio of the high frequency components Rh, Gh, and Bh is set in step S310, for example. , Kr: Kg: Kb = 1: 0: 0, and the process ends.

  In this way, by not mixing the high frequency components Rh, Gh, and Bh, it is possible to prevent the influence of color shift due to chromatic aberration of magnification from being reflected in the focus detection value, and to perform focus detection suitable for a subject with many R signal components. You can do it. On the other hand, if the value of the flag “max_col” is not 0, the process proceeds to step S311.

  In step S311, it is determined whether the value of the flag “max_col” is 1. When the value of the flag “max_col” is 1, that is, when the integral value Gv of the G signal is the largest in the focus detection region, the combined ratio of the high frequency components Rh, Gh, and Bh is set to, for example, Kr: Kg in step S312. : Kb = 0: 1: 1 is set, and the process ends.

  In this way, by not mixing the high frequency components Rh, Gh, and Bh, it is possible to prevent the influence of the color shift due to the chromatic aberration of magnification from being reflected in the focus detection value, and to perform focus detection suitable for a subject having a large G signal component. You can do it. On the other hand, if the value of the flag “max_col” is not 1, the process proceeds to step S313.

  In step S313, the value of the flag “max_col” is 2, that is, the integrated value Bv of the B signal is considered to be the largest in the focus detection region. Therefore, the synthesis ratio of the high frequency components Rh, Gh, and Bh is set to, for example, Kr: Kg: Kb = 0: 0: 1, and the process ends.

  By not mixing the high frequency components Rh, Gh, and Bh in this way, the influence of color shift due to lateral chromatic aberration is prevented from being reflected in the focus detection value. Furthermore, focus detection suitable for a subject having a large B signal component can be performed. After the above determination, the composition ratios Kr, Kg, and Kb are written in the AF-RAM 806, and the process of the composition ratio generation circuit 809 is completed.

  In the above processing, the position information of each focus detection area is defined by the distance D from the optical axis to the center position of each focus detection area. For example, as shown in FIG. 5, it is defined by the length of a line segment D connecting the center of the focus detection area a1 and the center of the focus detection area.

  Further, the chromatic aberration information specific to the lens is calculated by photographing a test chart or the like in advance at the time of factory shipment adjustment of the imaging apparatus.

  For example, while moving the zoom position of the lens, a chart on which subjects having the same frequency are displayed in each focus detection region as shown in FIG. 6 is photographed. Then, a high-frequency luminance component Yh obtained by synthesizing the high-frequency components Rh, Gh, and Bh of the RGB signal and the high-frequency components Rh, Gh, and Bh with Rh: Gh: Bh = 1: 1: 1 is obtained.

  Next, the high frequency component Gh and the luminance high frequency component Yh are integrated for each focus detection region, and focus detection values “Gh_sum” and “Yh_sum” are obtained in each focus detection region.

  Next, in each focus detection region, image data captured by controlling the lens position with the measurement value “Yh_sum” and image data captured by controlling the lens position with the focus detection value “Gh_sum” are acquired.

  Here, when a monochrome subject is photographed as shown in the chart of FIG. 6, the G signal has the highest content ratio in the luminance signal. Therefore, it is easy to obtain focus information for focus adjustment from image data obtained by controlling the lens position with the focus detection value “Gh_sum”.

  On the other hand, in the image data taken by controlling the lens position with the measured value “Yh_sum”, the displacement of the RGB image formation position increases as the distance from the optical axis increases due to the influence of lateral chromatic aberration, resulting in resolution. The feeling deteriorates.

  Accordingly, the image data captured by controlling the lens position with the focus detection value “Gh_sum” is used as a reference, and the sense of resolution of the image data captured by controlling the lens position with the measurement value “Yh_sum” is evaluated. Thereby, it is possible to detect the threshold value TH1 at which the resolution deterioration due to the chromatic aberration of magnification starts to appear for the distance D from the optical axis. As described above, the threshold TH1 data at which resolution degradation due to lateral chromatic aberration begins to appear is measured in advance and stored in the ROM 16 for each focal length.

  As described above with reference to FIGS. 2 to 6, the AF evaluation value generation circuit 8 calculates a plurality of focus detection values corresponding to a plurality of focus detection areas in the imaging screen as shown in FIG. Stored in the RAM 17. Thereafter, the system control unit 6 reads all focus detection values corresponding to the plurality of focus detection areas from the RAM 17. Then, size comparison, weighting calculation, and the like are performed on the plurality of focus detection values, and finally it is determined which position in the imaging screen is to be focused. Based on the result, information for lens position control is supplied to the drive circuit 4 of the optical system 1. Then, so-called autofocus control is performed by moving and controlling the lens of the optical system 1.

  As described above, according to the first embodiment, the influence of the lateral chromatic aberration of the imaging optical system is eliminated in consideration of the distance D between the optical axis and the focus detection area and the color signal information in the focus detection area. Thus, an AF evaluation value is generated. Therefore, the focusing accuracy can be improved in all focus detection areas in the imaging screen.

  Further, according to the first embodiment, it is possible to obtain a focus detection value in which the influence of the chromatic aberration of magnification of the imaging optical image system is eliminated in all focus detection areas in the imaging screen. Therefore, it is possible to control the focus detection values obtained from a plurality of focus detection areas under the same conditions, compare the sizes, etc., and automatically determine the focus position.

<Embodiment 2>
FIG. 7 is a block diagram illustrating a configuration of an imaging apparatus that is Embodiment 2 of the present invention. In the imaging apparatus according to the second embodiment, the AF evaluation value generation circuit 8 does not have the color detection circuit 808, and the synthesis ratio generation circuit 809 is different from the first embodiment. Since other configurations and operations are the same as those in the first embodiment, the same reference numerals are assigned and descriptions thereof are omitted. Hereinafter, the processing flow of the synthesis ratio generation circuit 809 in Embodiment 2 will be described with reference to the flowchart of FIG.

  In step S801 after the start of processing, the system control unit 6 reads chromatic aberration information specific to the lens from the ROM 16 and loads it into the RAM 17. The chromatic aberration information unique to the lens is, for example, data represented by a graph as shown in FIG. 4 and represents the degree of lateral chromatic aberration according to the focal length and the position of the focus detection region.

  In step S802, the system controller 6 calculates the focal length from the lens position. In step S803, the system control unit 6 calculates the position information of each focus detection area.

  In step S804, the focal length calculated in step S802 and the magnification chromatic aberration level corresponding to the position information of the focus detection area calculated in step S803 are calculated by the system control unit 6 from the chromatic aberration information unique to the lens stored in the RAM 17. read out.

  In step S805, the system control unit 6 compares the magnification chromatic aberration level read in step S804 with the predetermined threshold value TH1.

  When the degree of lateral chromatic aberration is smaller than the threshold value TH1, the process proceeds to step S806. In this case, since there is no adverse effect of lateral chromatic aberration, the combination ratio of the high frequency components Rh, Gh, and Bh is set to, for example, Kr: Kg: Kb = 5: 9: 2 so as to obtain a combination ratio that matches the visibility characteristic. Then, the process ends. On the other hand, if the degree of lateral chromatic aberration is greater than the threshold value TH1, the process proceeds to step S807.

  In step S807, the average saturation C of the focus detection area designated by the focus detection area counter is read from the AF-RAM 806 and compared with a predetermined threshold value TH2.

  If the saturation C is smaller than the threshold value TH2, the process proceeds to step S808. In this case, the saturation in the focus detection region is regarded as an achromatic color, and the combined ratio of the high-frequency components Rh, Gh, and Bh is set to Kr: Kg: Kb = so that the influence of the color shift due to the chromatic aberration of magnification is not reflected in the focus detection value. 0: 1: 0 is set, and the process ends.

On the other hand, when the saturation C is larger than the threshold value TH2, it is regarded as not an achromatic color, and the process proceeds to step S809. In step S809, the integration values Rav, Gav, and Bav of the RGB signals are read from the AF-RAM 806, and the synthesis ratios Rh, Gh, and Bh are set as, for example,
Kr: Kg: Kb = Rav / (Rav + Gav + Bav): Gav / (Rav + Gav + Bav): Bav / (Rav + Gav + Bav)

  As described above, when the focus detection area is an achromatic color in which lateral chromatic aberration is conspicuous, an evaluation value is generated only by the high frequency component Gh. On the other hand, if the focus detection area can be regarded as not having an achromatic color, the combined amount of the high-frequency components Rh, Gh, and Bh is adjusted according to the ratio of the RGB signal integral values Rav, Gav, Bav in the focus detection area. . Thereby, it is possible to reduce the influence of the color shift due to the chromatic aberration of magnification of the lens on the focus detection value, and it is possible to obtain an appropriate focus detection evaluation value for a chromatic object. After the above determination, the composition ratios Kr, Kg, and Kb are written in the AF-RAM 806, and the process of the composition ratio generation circuit 809 is completed.

<Embodiment 3>
FIG. 9 is a block diagram illustrating a configuration of the imaging apparatus according to the third embodiment of the present invention. The imaging apparatus according to the third embodiment is different from the first and second embodiments in that the AF evaluation value generation process is performed in conjunction with the image stabilization operation. Therefore, in FIG. 9, the same components as those in FIG. 1 are denoted by the same reference numerals and description thereof is omitted.

  In the third embodiment, a motion detection circuit 18 controlled by the system control unit 6 is added. The system control unit 6 determines an effective area of image data to be read from the solid-state imaging device 2 based on the motion information output from the motion detection circuit 18, and the timing signal generation circuit 5 determines the solid-state imaging device 2 and the AFE 3. A drive pulse for driving is generated. By this operation processing, for example, it is possible to obtain image data from which the influence of camera shake is removed.

  Then, the composition ratio generation circuit 809 included in the AF evaluation value generation circuit 8 considers the shift amount of the cutout position of the effective image area determined based on the motion information, and the distance between the center of the focus detection area and the optical axis. D1 is calculated.

  FIG. 10 is a schematic diagram when the cutout position of the effective image area is vertically shifted from the center of the image circle based on the motion information. Here, as the position of the center coordinate of each focus detection area, a value set in advance in a coordinate system with the optical axis as the origin is stored in the ROM 16.

The system control unit 6 reads from the ROM 16 position information of the center coordinates of each focus detection area in a state where the cutout position of the effective image area is not shifted. Then, using the shift amount of the effective image area determined based on the motion information, a distance D _n from the center of the focus detection area to the optical axis is calculated as in Expression 3 below.

As described above, the distance D _n from each focus detection region to the optical axis is obtained in consideration of the shift amount of the cutout position of the effective image region. As a result, even during the image stabilization operation, the influence of the chromatic aberration of magnification of the lens is eliminated according to the position information of the focus detection area and the color signal information in the focus detection area, and an appropriate focus detection evaluation value is obtained from all the focus detection areas. Obtainable.

  It is also possible to supply a storage medium storing software program codes for realizing the functions of the above-described embodiments to a system or apparatus. That is, it goes without saying that this can also be achieved by the computer (or CPU or MPU) of the system or apparatus reading and executing the program code stored in the storage medium.

  As a storage medium for supplying the program code, for example, a flexible disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD-R, magnetic tape, nonvolatile semiconductor memory card, ROM, or the like can be used. . Further, the functions of the above-described embodiments may be realized by executing the program code read by the computer.

  However, when the OS (operating system) operating on the computer performs part or all of the actual processing based on the instruction of the program code, and the functions of the above-described embodiments are realized by the processing. Needless to say, is also included.

  Furthermore, the program code read from the storage medium may be written in a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer. After that, based on the instruction of the program code, the CPU of the function expansion board or function expansion unit performs part or all of the actual processing, and the processing of the above-described embodiment is realized by the processing. Needless to say.

It is a block diagram which shows the internal structure of the whole imaging device concerning Embodiment 1 of this invention. It is a flowchart figure which shows operation | movement of the AF evaluation value generation circuit used with the imaging device concerning Embodiment 1 of this invention. It is a flowchart figure which shows the operation | movement of the synthetic | combination ratio production | generation circuit used with the imaging device concerning Embodiment 1 of this invention. It is a characteristic view which shows the position information of the focus detection area | region used with the imaging device concerning Embodiment 1 of this invention, and the level of a magnification chromatic aberration. It is a schematic diagram which shows the focus detection area | region of the AF evaluation value used with the imaging device concerning Embodiment 1 of this invention. It is a schematic diagram which shows an example of the test chart for acquiring the chromatic aberration information used with the imaging device concerning Embodiment 1 of this invention. It is a block diagram which shows the internal structure of the whole imaging device concerning Embodiment 2 of this invention. It is a flowchart figure which shows operation | movement of the synthetic | combination ratio production | generation circuit used with the imaging device concerning Embodiment 2 of this invention. It is a block diagram which shows the internal structure of the whole imaging device concerning Embodiment 3 of this invention. It is a schematic diagram which shows the focus detection area | region of AF evaluation value used with the imaging device concerning Embodiment 3 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical system 2 Solid-state image sensor 3 Analog front end part 4 Drive circuit 5 Timing signal generation circuit 6 System control part 7 Camera signal processing circuit 8 AF evaluation value generation circuit 9 Image memory 10 Encoding compression processing circuit 11 Recording processing circuit 12 Recording Medium 13 Display control circuit 14 Image display device 15 Bus 16 Program 17 Volatile memory

Claims (9)

Imaging means for capturing a subject image and outputting image data ;
Separating means for separating the image data obtained from the imaging means into a plurality of color signal components;
High frequency component detection means for detecting high frequency components for each of the plurality of color signal components output from the separation means;
Relates focus detection areas set in a plurality of positions in the imaging screen of the imaging means, and the focus detection area position information detecting means for the position in the imaging screen of each focus detection area is calculated to information I Table,
Color signal information detecting means for detecting color signal information for each focus detection area;
For each of the focus detecting area, on the basis of the position information representing the said color signal information in the imaging screen, synthesizing each of the high-frequency component output from the high frequency component detection means, generating a focus detection evaluation value An imaging apparatus comprising: a focus detection evaluation value generation unit that performs the following. The focus detection region position information detection means calculates a distance from the optical axis in each focus detection region to the center of each focus detection region as information representing a position in the imaging screen ,
The focus detection evaluation value generation means, based on said distance and the color signal information, the imaging apparatus according to claim 1, characterized in that combining the high frequency components. Motion detection means;
An image stabilization control unit configured to control a cutout position of an effective image data area in the imaging screen of the imaging unit based on motion information output from the motion detection unit;
The focus detection region position information detection unit, when the image stabilization control unit operates , displays information representing a position in the imaging screen based on the cutout position of the effective image data region by the image stabilization control unit. The imaging device according to claim 1, wherein the imaging device is calculated. The focus detection evaluation value generation means includes
When the distance, which is information representing the position in the imaging screen, is smaller than a specific value, the respective high frequency components are combined in accordance with the visibility characteristics,
The imaging apparatus according to claim 2 , wherein when the distance is equal to or greater than the specific value, the high-frequency components are combined with reference to the color signal information. The focus detection evaluation value generation means refers to the color signal information when the distance, which is information representing a position in the imaging screen, is equal to or greater than a specific value, and is a dominant color within the focus detection area. 5. The imaging apparatus according to claim 2 , wherein the high-frequency components are combined so that a combination ratio of the high-frequency components corresponding to the frequency increases. The color signal information detecting means detects an average saturation and hue in the focus detection area,
The focus detection evaluation value generation means has a dominant color in the focus detection region as the saturation increases when the distance, which is information representing a position in the imaging screen, is equal to or greater than a specific value. 6. The imaging apparatus according to claim 2 , wherein the high-frequency components are combined so that a combination ratio of the corresponding high-frequency components is increased. A separation step of separating the image data output from the imaging means into a plurality of color signal components;
A high-frequency component detection step for detecting a high-frequency component for each of the plurality of color signal components output in the separation step;
A plurality of relates focus detection areas set in position, the focus detecting area position information detection step of the position in the imaging screen of each focus detection area is calculated to information I table in the imaging screen in the image pickup means,
A color signal information detection step of detecting color signal information for each focus detection region;
For each of the focus detecting area, on the basis of the position information representing the said color signal information in the imaging screen, synthesizing each of the high-frequency component output from the high-frequency component detecting step, generating a focus detection evaluation value And a focus detection evaluation value generating step.   A computer-executable program describing a procedure of a control method for an imaging apparatus according to claim 7.   A storage medium storing a computer-executable program describing a procedure of a control method for an imaging apparatus according to claim 7.

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