JP4547465B2 - Imaging apparatus and exposure control method - Google Patents

Description

  The present invention relates to a photographing lens having a variable focal length, a photographing device including a solid-state imaging device and a strobe device for photographing subject light transmitted through the photographing lens, and an exposure control method thereof.

  In recent years, digital cameras, which are photographing devices that record image data picked up by a solid-state image pickup device such as a CCD image sensor, have been widely used. In such a digital camera, when the subject brightness is low, the strobe device shoots the subject by irradiating the subject with strobe light.

However, when the shooting distance is long, the strobe light does not reach the subject and underexposure occurs. In order to solve such a problem, there is known a digital camera that solves the shortage of exposure by amplifying the imaging signal output from the solid-state imaging device with a gain corresponding to the imaging distance and changing the imaging sensitivity. (For example, refer to Patent Document 1).

Also, based on the shooting distance, set the shooting sensitivity and the dimming value as the reference value for stopping the flash firing, and set the shooting distance range that can be adjusted with the auto flash function by performing flash photography. An expanded digital camera is known (for example, see Patent Document 2).

In addition, the strobe device performs a plurality of times of preliminary light emission with a certain amount of light, and performs a plurality of times of imaging. The imaging signal obtained by this imaging is amplified with a different gain for each imaging, and the signal level of the amplified imaging signal There is known a digital camera that obtains an optimum light amount by setting the light amount of the main light emission based on the amplified imaging signal when it is determined that is within a predetermined range (see, for example, Patent Document 3).

JP-A-6-121225 JP 2000-134533 A JP-A-11-84489

  However, in the digital cameras described in Patent Document 1 and Patent Document 2, the shooting sensitivity and the dimming value of the strobe device are set based on the shooting distance, but the arrival distance of the strobe light is only the shooting distance. In addition, because of the brightness of the lens, there is a problem that it is difficult to appropriately control the amount of strobe light. In addition, the digital camera described in Patent Document 3 has a problem that it is necessary to perform preliminary light emission a plurality of times, and it takes time for photographing processing.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an imaging apparatus and an exposure control method capable of performing rapid imaging processing with an appropriate amount of strobe light.

  In order to solve the above-described problems, an imaging apparatus according to the present invention includes a photographic lens having a zoom lens and a focus lens, a solid-state imaging device that captures subject light that has passed through the photographic lens, and flash light that is directed toward the subject. And a strobe device that performs photometry of subject brightness, zoom position detection means for detecting the zoom position of the zoom lens, and focus position detection for detecting the focus position of the focus lens A photosensitivity setting unit for setting a photosensitivity based on the zoom position detected by the zoom position detection unit and the focus position detected by the focus position detection unit; and the photometry by the photometry unit. Based on the subject brightness and the photographing sensitivity set by the photographing sensitivity setting means, the exposure and the flash device And control means for controlling the amount of light emission, and is characterized in that it comprises a first amplifying means for amplifying the image signal output from the solid-state imaging device with a gain corresponding to the imaging sensitivity. The photographing sensitivity setting means includes a first distance selection parameter on the Far end side and a second distance selection parameter on the Near end side set on the moving range of the focus lens based on the zoom position detected by the zoom position detection means. Is selected from values set in advance for each zoom position, and when the in-focus position detected by the in-focus position detection means is closer to the Near end than the second distance selection parameter, the photographing sensitivity is set to low sensitivity, When the in-focus position is between the first distance selection parameter and the second distance selection parameter, the photographing sensitivity is set to medium sensitivity, and when the in-focus position is far end side than the first distance selection parameter. Set the shooting sensitivity to high sensitivity.

  Further, the in-focus position detecting unit extracts a high frequency component from image data obtained by converting the imaging signal into a digital signal for each position of the focus lens, and an integrating unit that integrates the high frequency component; It is preferable to include a determination unit that acquires an integrated value integrated by the integrating unit and determines a position where the integrated value is maximum, and detects a position where the integrated value is maximum as the in-focus position.

  Further, the brightness value of the image data is calculated, and the brightness value is calculated by comparing the brightness value with a preset target brightness value to calculate an insufficient gain value, and the insufficient gain calculation means. It is preferable that a second amplifying unit that amplifies the signal level of the image data based on the insufficient gain value is provided.

  Further, the photographing sensitivity setting means sets a plurality of kinds of the photographing sensitivities, and the control means sets exposure values corresponding to the respective photographing sensitivities, and continuously for the set number of the photographing sensitivity and the exposure value. Shooting may be executed.

  Furthermore, the image processing apparatus further includes display means for displaying an image, and the control means can control the display means to select at least one of a plurality of photographed images obtained by the continuous photographing. It is preferable to display a selection screen.

  In addition, based on the setting value selected by the setting value selection unit, a setting value selection unit that selects a setting value used when performing various signal processing on the image data, for each of the imaging sensitivity, It is preferable that the image processing apparatus includes signal processing means for applying the various signals to the image data.

  Furthermore, the set value specifies a parameter for specifying a gradation conversion characteristic used when gradation conversion processing is performed on the image data, and a correction amount range when performing edge enhancement processing on the image data. It is preferable that the parameter is a parameter that specifies a filter threshold value used when noise reduction processing is performed on the image data.

  The exposure control method of the present invention includes a photographic lens having a zoom lens and a focus lens, a solid-state imaging device that images subject light transmitted through the photographic lens, and a strobe device that irradiates strobe light toward the subject. An exposure control method for a photographing apparatus, wherein the subject luminance is measured, the zoom position of the zoom lens is detected, the focus position of the focus lens is detected, and the photographing sensitivity is adjusted based on the zoom position and the focus position. Setting, controlling the exposure and the light emission amount of the strobe device based on the subject brightness and the shooting sensitivity, and amplifying the imaging signal output from the solid-state imaging device with a gain corresponding to the shooting sensitivity. It is a feature. When setting the shooting sensitivity, the first distance selection parameter on the Far end side and the second distance selection parameter on the Near end side set on the moving range of the focus lens are previously set for each zoom position based on the zoom position. When the focus position is closer to the Near end than the second distance selection parameter, the photographing sensitivity is set to a low sensitivity, and the focus position is set to the first distance selection parameter and the second distance selection parameter. When it is between the distance selection parameters, the shooting sensitivity is set to medium sensitivity, and when the focus position is far from the first distance selection parameter, the shooting sensitivity is set to high sensitivity.

  According to the present invention, the shooting sensitivity is set based on the zoom position of the zoom lens and the focus position of the focus lens, and the exposure and strobe light amount are controlled based on this shooting sensitivity, so the focal length of the shooting lens is changed. Even when the brightness of the lens changes, it is possible to appropriately control the exposure and the amount of strobe light. For this reason, it is possible to prevent the strobe light not reaching in the long distance shooting and the white stripe caused by the strobe light in the short distance shooting. In addition, since it is not necessary to perform preliminary light emission a plurality of times, it is possible to perform quick photographing.

  In addition, since the insufficient gain of the image data is adjusted when shooting is performed, the image quality of the shot image can be improved. Furthermore, since a plurality of types of shooting sensitivity are set, and continuous shooting is performed by setting an exposure value corresponding to each shooting sensitivity, it is possible to provide a shot image more suitable for the photographer's intention.

  Further, when various signal processing is performed on the image data, the signal processing is performed based on the set value set for each photographing sensitivity, so that the image quality of the photographed image can be further improved.

It is a perspective view which shows the structure of the front side of a digital camera. It is a perspective view which shows the structure of the back side of a digital camera. It is a block diagram which shows the electric constitution of the digital camera which is 1st Embodiment. It is explanatory drawing which shows the input / output data of an imaging sensitivity setting circuit. It is explanatory drawing which shows a distance selection parameter. It is a flowchart explaining an imaging | photography process. It is a flowchart explaining an exposure control process. It is a flowchart explaining imaging processing, and shows a case where a plurality of imaging sensitivities are set to perform continuous imaging. It is explanatory drawing which shows the selection screen which selects the image image | photographed with different imaging sensitivity. It is a block diagram which shows the electric constitution of the digital camera which is 2nd Embodiment. It is explanatory drawing which shows the input-output data of an insufficient gain calculation circuit. It is the schematic which shows the structure of an insufficient gain calculation circuit. It is explanatory drawing which shows the weighting coefficient for every area. It is a flowchart explaining an imaging | photography process, and has shown the case where an insufficient gain is calculated based on image data and a gain is adjusted. It is a block diagram which shows the electric constitution of the digital camera which is 3rd Embodiment. It is the schematic which shows the structure of a digital signal processing part. It is explanatory drawing which shows the input-output data of a signal processing parameter calculation circuit. It is the schematic which shows the structure of a signal processing parameter calculation circuit. It is a graph which shows the correction amount range for every imaging | photography sensitivity in an outline emphasis process. It is a schematic diagram which shows the arrangement | sequence of a pixel. It is a graph which shows the outline component of a pixel row. It is a flowchart explaining imaging processing, and shows a case where signal processing corresponding to imaging sensitivity is performed on image data.

  A digital camera (photographing device) 10 shown in FIG. 1 includes a lens barrier 12 that can be slid on the front surface of a camera body 11. By sliding the lens barrier 12 to the open position (position shown in FIG. 1), the photographing lens 13 and the strobe light emitting unit 14 are exposed on the front surface. Further, a finder objective window 15 constituting an optical finder is provided on the front surface of the camera body 11.

  The above-described lens barrier 12 also serves as a power operation member, and when the slide operation is performed to the above-described open position, the power source of the camera body 11 is turned on and the photographing lens 13 and the strobe light emitting unit 14 are shielded. When the camera is slid, the camera body 11 is turned off.

  Further, as shown in FIG. 2, on the back surface of the camera body 11, an LCD 16 serving as a display means for displaying an image, a finder eyepiece window 17 constituting an optical finder, and an operation unit 18 constituted by a plurality of operation members are provided. It has been. The LCD 16 displays a through image, a reproduced image, various setting screens, and the like.

  The operation unit 18 includes a mode switching button 21, a return button 22, a feed button 23, a zoom button 24, a menu button 25, a cancel button 26, and a display button 27.

  The mode switching button 21 is slid when switching between the shooting mode and the playback mode. The feed button 23 and the return button 22 are pressed when the playback image is forwardly and backwardly fed in the playback mode. The zoom button 24 is pressed in the vertical direction when changing the focal length of the taking lens 13. The return button 22, the feed button 23, and the zoom button 24 are also used as cursor operation buttons when moving the cursor in the setting screen.

  The menu button 25 is pressed when a menu screen is displayed on the LCD 16. The cancel button 26 is pressed to stop various setting operations on the menu screen or return to the previous screen. The display button 27 is pressed when the LCD 16 is switched on and off.

  A shutter button 28 is provided on the upper surface of the camera body 11. The shutter button 28 is a two-stage push button. When the shutter button 28 is half-pressed, various shooting preparation processes are executed. When the shutter button 28 is further pressed halfway down and fully pressed, the shooting process is executed. Is done.

  A recording media slot 30 is provided on the side surface of the camera body 11. The recording medium slot 30 is detachably loaded with a recording medium 31 which is a storage means for storing image data.

  Next, the electrical configuration of the digital camera 10 will be described. As shown in FIG. 3, each part of the digital camera 10 is controlled by a system controller (control means) 40. The system controller 40 includes a ROM 40a and a RAM 40b.

  The ROM 40a stores a control program for controlling each unit in the camera body 11, various control data, and the like, and the RAM 40b temporarily stores work data. The system controller 40 controls each unit based on these programs and various control data.

  Further, the operation unit 18 and the shutter button 28 are connected to the system controller 40, and each unit is controlled based on operation signals input from the operation unit 18 and the shutter button 28.

  The photographing lens 13 is a lens whose focal length can be changed, and includes a zoom lens 41, a diaphragm 42, and a focus lens 43. The zoom lens 41 is moved along the optical axis direction of the photographing lens 13 by a zoom pulse motor 44. The aperture 42 is driven by an iris motor 45 to change the aperture diameter, and adjusts the amount of subject light incident on the light receiving surface of a CCD image sensor (hereinafter simply referred to as CCD), which will be described later. Further, the focus lens 43 is moved along the optical axis direction by the focus pulse motor 46.

  Each motor 44 to 46 is connected to a motor driver 47. The motor driver 47 is connected to the system controller 40, and transmits drive pulses to the motors 44 to 46 based on instructions from the system controller 40. Each motor 44-46 is rotationally driven by this drive pulse. The system controller 40 is zoom position detection means for detecting the zoom position of the zoom lens 41, and detects the zoom position by counting the number of drive pulses of the zoom pulse motor 44. For example, the number of pulses is added when the zoom lens 41 is moved toward the tele end, and the number of pulses is subtracted when the zoom lens 41 is moved toward the wide end. Similarly, the system controller 40 detects the position of the focus lens 43 based on the number of focus pulses obtained by counting the number of pulses of the focus pulse motor 46.

  A CCD 48 is disposed behind the photographic lens 13. The CCD 48 includes a light receiving surface in which light receiving elements (photodiodes) are two-dimensionally arranged. The CCD 48 photoelectrically converts subject light that has passed through the photographing lens 13 and formed an image on the light receiving surface, and a signal corresponding to the amount of light. Accumulate charge. The signal charge accumulated in each light receiving element is sequentially read out as a voltage signal (imaging signal) corresponding to the amount of charge based on a pulse applied from the CCD driver 49.

  The imaging signal output from the CCD 48 is input to the analog signal processing unit 50. The analog signal processing unit 50 includes a correlated double sampling circuit (CDS) 50a, an auto gain control amplifier (AMP) 50b, and an A / D converter 50c.

  The CDS 50a removes amplifier noise and reset noise caused by the CCD 48 from the imaging signal. The AMP 50b is a first amplifying unit. The system controller 40 acquires shooting sensitivity information from a shooting sensitivity setting circuit described later, controls the AMP 50b, and amplifies the imaging signal with a gain corresponding to the shooting sensitivity. Further, the A / D converter 50c converts an imaging signal that is an analog signal into image data of a digital signal.

  A timing generator (TG) 51 provides timing signals to the CCD driver 49 and the analog signal processing unit 50 in accordance with instructions from the system controller 40, and the circuits are synchronized by this timing signal. The electronic shutter speed (exposure time) of the CCD 48 is determined by the timing signal (clock pulse) input from the TG 49. That is, the system controller 40 performs exposure control by controlling the aperture value of the aperture 42 and the exposure time of the CCD 48.

  An image input controller 52 is connected to the analog signal processing unit 50. The image input controller 52 is connected to the SDRAM 54 via the bus 53, and stores image data for one screen in the SDRAM 54. In addition to the image input controller 52 and the SDRAM 54, the bus 53 includes a digital signal processing circuit 55, a compression / decompression processing circuit 56, an LCD driver 57, a media controller 58, an AE detection circuit 59, an AF detection circuit 60, and a photographing sensitivity setting circuit. 61 is connected.

  The digital signal processing circuit 55 performs predetermined signal processing such as gradation conversion processing, contour enhancement processing, noise reduction processing, white balance correction processing, and YC conversion processing on the image data stored in the SDRAM 54. When displaying a through image, image data having a lower resolution than that at the time of shooting is stored in the SDRAM 54, and the above-described signal processing is performed on the low-resolution image data. Thereafter, in accordance with instructions from the system controller 40, low-resolution image data is sequentially read from the SDRAM 54 and displayed on the LCD 16 as a through image via the LCD driver 57.

  The shutter button 28 described above is a two-stage pressing type switch. When the shutter button 28 is lightly pressed (half-pressed) and the first-stage switch is turned on, the AE control and AF control described later are performed. A shooting preparation operation is performed. When the shutter button 28 is half-pressed and then further pressed (fully pressed), the main exposure is performed on the CCD 48 with the exposure value set by the AE control.

  At this time, the above-described SDRAM 54 stores image data having a higher resolution than that of the through image, and the above-described signal processing is performed on the image data. The image data subjected to the signal processing is compressed in a predetermined compression format (for example, JPEG format) by the compression / decompression processing circuit 56. After the compression processing, the image data is stored in the recording medium 31 via the media controller 58.

  In the reproduction mode, the image data read from the recording medium 31 via the media controller 58 is decompressed by the compression / decompression processing circuit 56 and displayed as a reproduction image on the LCD 16 via the LCD driver 57.

  The AE detection circuit 59 is a photometric means for measuring subject luminance based on the image data stored in the SDRAM 54 when the shutter button 28 is half-pressed, and detects an AE evaluation value at which the exposure value is optimal. The AE evaluation value is output to the system controller 40. The AF detection circuit 60 is an integration unit that extracts high frequency components of image data and integrates the high frequency components. When the shutter button 28 is half-pressed and the focus lens 43 is moved in the optical axis direction, Based on the image data stored in the SDRAM 54, an AF evaluation value that is an integrated value of the high frequency components of the image data is sequentially calculated, and this AF evaluation value is output to the system controller 40.

  The system controller 40 sets the aperture diameter of the diaphragm 42 and the electronic shutter speed of the CCD 48 based on the AE evaluation value. Furthermore, the system controller 40 is a determination unit that sequentially acquires AF evaluation values at each position of the focus lens 43 and determines a position at which the AF evaluation value is maximum (peak). That is, the system controller 40 sequentially acquires the AF evaluation value from the AF detection circuit 60, determines the position of the focus lens 43 at which the AF evaluation value is maximum (peak) as the in-focus position, and sets the focus lens at the in-focus position. 43 is moved. The in-focus position detection means includes an AF detection circuit 60 and a system controller 40.

  The photographing sensitivity setting circuit 61 is photographing sensitivity setting means for setting photographing sensitivity based on the current focal length of the photographing lens 13 and the in-focus position of the focus lens 43, and is photographed when the shutter button 28 is half-pressed. Sensitivity is set and photographing sensitivity information is output to the system controller 40.

  That is, as shown in FIG. 4, the photographing sensitivity setting circuit 61 receives a zoom position as focal length information and the number of focus pulses as a focus position. The photographing sensitivity setting circuit 61 sets the optimum photographing sensitivity based on these, and outputs this photographing sensitivity information (ISO 400, 800, 1600, etc.) to the system controller 40. In the present embodiment, a case where selection is made from three shooting sensitivities will be described as an example.

  A method for setting the photographing sensitivity will be described below. The imaging sensitivity setting circuit 61 stores a table shown in Table 1 below. This table shows distance selection parameters A and B for each zoom position (Z1 to Z10). The distance selection parameter A (first distance selection parameter) and the distance selection parameter B (second distance selection parameter) are set by the number of focus pulses. As shown in FIG. It is set between the Far end (the number of focus pulses: 0) of the focus lens 43 and the Near end, and the distance parameter A is set to the Far end side with respect to the distance parameter B.

  The photographing sensitivity setting circuit 61 acquires information on the zoom position (Z1 to Z10) and information on the number of focus pulses from the system controller 40, and selects distance selection parameters A and B corresponding to the current zoom position. Thereafter, the imaging sensitivity setting circuit 61 sets the number of focus pulses at the in-focus position to any range of the Far end side from the distance selection parameter A, the distance selection parameters A and B, and the Near end side from the distance selection parameter. Determine if there is.

  The shooting sensitivity setting circuit 61 sets the shooting sensitivity to a high sensitivity when it is far from the distance selection parameter A, and sets the shooting sensitivity to a medium sensitivity when it is between the distance selection parameters A and B. If it is closer to the Near end than the selected parameter, the imaging sensitivity is set to a low sensitivity. Thereafter, the shooting sensitivity setting circuit 61 outputs the set shooting sensitivity information to the system controller 40.

  Further, a strobe device 62 for irradiating a subject with strobe light is connected to the system controller 40 described above. The system controller 40 controls the strobe device 62 to adjust the amount of strobe light.

  Next, photographing processing of the digital camera 10 having the above configuration will be described with reference to the flowchart of FIG. When the power of the digital camera 10 is turned on and the photographing mode is set, a through image is displayed on the LCD 16 and the system controller 40 determines whether or not the shutter button 28 is half-pressed. If it is determined that the shutter button is not half-pressed, the standby state is maintained until the shutter button 28 is half-pressed.

  When it is determined that the shutter button 28 is half-pressed, the system controller 40 controls the AE detection circuit 59 to execute the photometric process. The AE detection circuit 59 measures the subject luminance based on the low resolution image data stored in the SDRAM 54 and outputs the AE evaluation value to the system controller 40. The system controller 40 calculates an AF exposure value based on the AE evaluation value, and sets the aperture diameter of the diaphragm 32 and the electronic shutter speed of the CCD 48. With this exposure setting, imaging is performed by the CCD 48 and image data is taken into the SDRAM 54.

  At this time, the system controller 40 controls the motor driver 47 to move the focus lens 43 between the Far end and the Near end, and controls the AF detection circuit 60 to execute the AF process. The AF detection circuit 60 calculates an AF evaluation value for each position of the focus lens 43 based on the image data input to the SDRAM 54 and sequentially outputs the AF evaluation value to the system controller 40.

  The system controller 40 sequentially acquires AF evaluation values from the AF detection circuit 60, determines a position (number of focus pulses) at which the AF evaluation value is maximum (peak), and determines this position as a focus position of the focus lens 43. Detect as.

  Thereafter, the system controller 40 executes an exposure control process. Hereinafter, the exposure control process will be described with reference to the flowchart of FIG. The system controller 40 outputs zoom position information (Z1 to Z10) indicating the current position of the zoom lens 41 and in-focus position information (number of focus pulses) of the focus lens 43 to the imaging sensitivity setting circuit 61.

  When the imaging sensitivity setting circuit 61 acquires the zoom position information and the focus position information, the imaging sensitivity setting circuit 61 refers to the table shown in Table 1 and sets the number of focus pulses of the distance selection parameters A and B corresponding to the current zoom position. . For example, when the zoom position is Z6, the distance selection parameter A is set to 10 and the distance selection parameter B is set to 18.

  Thereafter, the photographing sensitivity setting circuit 61 determines whether or not the number of focus pulses at the focus position is larger than the distance selection parameter B. When it is determined that the distance is larger than the distance selection parameter B, the photographing sensitivity setting circuit 61 sets the photographing sensitivity to a low sensitivity (for example, ISO 400). If it is determined that the distance selection parameter B is equal to or less than the distance selection parameter B, the imaging sensitivity setting circuit 61 determines whether the focus pulse number is equal to or less than the distance selection parameter A.

  If it is determined that the distance selection parameter A is equal to or less than the distance selection parameter A, the photographing sensitivity setting circuit 61 sets the photographing sensitivity to a medium sensitivity (for example, ISO 800). When it is determined that the distance selection parameter A is larger than the distance selection parameter A, the photographing sensitivity setting circuit 61 sets the photographing sensitivity to high sensitivity (for example, ISO 1600). The photographing sensitivity setting circuit 61 outputs information on the set photographing sensitivity to the system controller 40.

  The system controller 40 sets the flash emission amount and the exposure value based on the AE evaluation value and the photographing sensitivity. Further, the system controller 40 controls the AMP 50b based on the photographing sensitivity information, and sets a gain corresponding to the photographing sensitivity.

  Thereafter, the system controller 40 determines whether or not the shutter button 28 has been fully pressed. If it is determined that the button is not fully pressed, the standby state is maintained until the button is fully pressed. If it is determined that the shutter button 28 has been fully pressed, the system controller 40 controls the aperture diameter of the diaphragm 42 and the electronic shutter speed of the CCD 48 and the amount of light emitted from the strobe based on the exposure value setting. Then, the CCD 48 is caused to execute an imaging process.

  At this time, the system controller 40 controls the AMP 50b to amplify the imaging signal output from the CCD 48 with a gain corresponding to the imaging sensitivity. Thereafter, image data obtained by converting the imaging signal into a digital signal is stored in the SDRAM 54.

  Thereafter, the system controller 40 controls the digital signal processing circuit 55 to perform various signal processing on the high-resolution image data stored in the SDRAM 54 and also controls the compression / decompression processing circuit 56 to convert the image data into image data. On the other hand, compression processing is performed.

  The system controller 40 controls the media controller 58 to store the image data subjected to the compression process in the recording medium 31 and ends the photographing process.

  In the description of the shooting process, the case where shooting is performed with one shooting sensitivity set based on the zoom position and the focus position has been described as an example. As described above, it is best to perform one shooting with the optimum shooting sensitivity. However, the focus is shifted due to the temperature characteristics of the shooting lens, and the zoom lens and the focus lens are repeatedly moved to deteriorate the drive unit. In some cases, an appropriate subject distance may not be obtained due to variations in the lens position caused by. Also, depending on the photographer, even if the main subject is a little too bright, the preference is divided such as emphasizing the background image, so multiple images can be taken with multiple sensitivity to provide an image that suits the photographer's intention. You may do it.

  Hereinafter, a shooting process when a plurality of shooting sensitivities are set and shooting is performed a plurality of times for each shooting sensitivity will be described with reference to the flowchart of FIG. Since the same processing is performed up to the AF processing, description thereof is omitted.

  After the AF processing is performed, the system controller 40 outputs the current zoom position information (Z1 to Z10) and focus lens focus position information (number of focus pulses) to the imaging sensitivity setting circuit 61.

  The photographing sensitivity setting circuit 61 sets an optimum photographing sensitivity in the same manner as the exposure control process described above. Thereafter, the photographing sensitivity setting circuit 61 sets three photographing sensitivities: an optimum photographing sensitivity, a photographing sensitivity that is lower than the optimum photographing sensitivity, and a photographing sensitivity that is higher than the optimum photographing sensitivity. For example, when the optimum shooting sensitivity is set to ISO 800, three shooting sensitivities of ISO 400, 800, and 1600 are set as the shooting sensitivity. The shooting sensitivity setting circuit 61 outputs these three types of shooting sensitivity information to the system controller 40.

  The system controller 40 sets the gain, exposure value, and strobe emission amount corresponding to each shooting sensitivity based on these shooting sensitivity and AE evaluation value, and stores these three types of setting information in the RAM 40b. Thereafter, the system controller 40 determines whether or not the shutter button 28 has been fully pressed. If it is determined that the button is not fully pressed, the standby state is maintained until the button is fully pressed.

  When it is determined that the shutter button 28 is fully pressed, the system controller 40 controls each unit based on one setting information out of the three setting information, and executes an imaging process. Further, the system controller 40 controls each unit to perform various image processing and compression processing on the image data, and then stores the image data in a recording medium.

  Thereafter, the system controller determines whether the storage of the three images has been completed. When it is determined that the storage of the three images has not been completed, the process returns to the imaging process and the image is stored based on the remaining setting information.

  If it is determined that the storage of the three images has been completed, the system controller 40 controls the media controller 58 to read out the three image data and controls the compression / decompression processing circuit 56 to A decompression process is performed on the image data.

  Thereafter, the system controller 40 controls the LCD driver 57 to display the selection screen 70 shown in FIG. 9 on the LCD 16. On this selection screen 70, three images 71a to 71c are reduced and displayed, and the user can select a desired image by operating the operation unit 18.

  Thereafter, the system controller 40 deletes image data other than the image selected by the user from the recording medium 31, and ends the photographing process.

  In the description of the shooting process, the case where the selection screen 70 is displayed and image data other than the image selected by the user is deleted has been described as an example. However, the shooting process ends without displaying the selection screen 70. Later, the user may delete unnecessary image data by operating the operation unit. In the above description of the shooting process, the case where three shooting sensitivities are set has been described. However, the present invention is not limited to this, and two or four or more shooting sensitivities may be set.

  Next, a digital camera 80 according to the second embodiment will be described. As shown in FIG. 10, the digital camera 80 includes an insufficient gain calculation circuit 81 and a digital signal processing circuit 82. The deficient gain calculation circuit 81 is deficient gain value calculation means for calculating deficient gain values of image data based on image data stored in the SDRAM 54 at the time of shooting processing. As shown in FIG. 11, the insufficient gain calculation circuit 81 receives the integration data for each divided area and the pixel count data in one area, and calculates and outputs an insufficient gain value.

  The insufficient gain calculation circuit 81 will be described below. As shown in FIG. 12, the insufficient gain calculation circuit 81 includes a luminance data conversion unit 81a, a weighted average processing unit 81b, a luminance level calculation unit 81c, and a gain value calculation unit 81d. The luminance data conversion unit 81a receives the integrated data for each divided area and the area size data. The integrated data for each divided area is R / G / B integrated data for each area obtained by dividing the image data into a predetermined number, and the area size data is the pixel number data in the divided area. In this embodiment, the case where image data is divided into 64 parts will be described as an example, but the number of divisions can be changed as appropriate. Further, the system controller 40 may calculate R / G / B integrated data for each area, or the AE detection circuit 59 may calculate this integrated data.

  The luminance data conversion unit 81a acquires R (i), G (i), and B (i) that are integrated data for each divided area, and calculates the luminance data Y (i) of each area according to the following Equation 1. . The luminance data conversion unit 81a outputs the luminance data Y (i) to the weighted average processing unit 81b.

(Equation 1)
Y (i) = 0.6 × G (i) + 0.3 × R (i) + 0.1 × B (i)
(However, i: 0 to 63)

  Thereafter, the weighted average processing unit 81b performs weighted average processing on the luminance data Y (i). That is, the weighted average processing unit 81b assumes that there is a main subject at the center of the screen, and weights the luminance data Y (i) of each area using the weighting coefficient table shown in FIG. The average value Yk of the luminance data Y (i) is calculated by the following formula 2. The weighted average processing unit 81b outputs the average value Yk to the luminance level calculation unit 81c.

The average value Yk and the pixel number data in one area are input to the luminance level calculation unit 81c. The luminance level calculation unit 81c calculates the luminance level Yp per pixel according to the following mathematical formula 3. The luminance level calculation unit 81c outputs the luminance level Yp to the insufficient gain value calculation unit 81d.

(Equation 3)
Yp = Yk / (number of pixels in one area)

  The deficient gain value calculation unit 81d calculates the deficient gain value (crct_gain) by the following mathematical formula 4, and outputs the deficient gain value (crct_gain) to the digital signal processing circuit 82.

(Equation 4)
crct_gain = (target level) / Yp

  In addition, the digital signal processing circuit 82 includes an insufficient gain adjusting unit 82a that is a second amplifying unit. The insufficient gain adjustment unit 82a corrects the insufficient gain by adjusting the gain of the image data stored in the SDRAM 54 based on the insufficient gain value (crct_gain).

  The configuration of the digital camera 80 has been described above, but the other configurations are the same as those of the digital camera 10, and the same components are denoted by the same reference numerals and detailed description thereof is omitted.

  Next, photographing processing of the digital camera 80 having the above configuration will be described with reference to the flowchart of FIG. Since the processing up to exposure control is the same as that of the digital camera 10 according to the first embodiment, the description thereof is omitted. Similar to the digital camera 10, when the exposure control process is performed, the system controller 40 determines whether or not the shutter button 28 has been fully pressed.

  When it is determined that the shutter button 28 is not fully pressed, the standby state is maintained until the shutter button 28 is fully pressed. If it is determined that the shutter button is fully pressed, the system controller controls the aperture diameter of the aperture and the electronic shutter speed based on the exposure value setting, and also controls the light emission amount of the strobe to control the CCD. The main exposure is performed.

  At this time, the system controller amplifies the imaging signal acquired by the CCD with a set gain by controlling the AMP. Thereafter, high-resolution image data obtained by converting the imaging signal into a digital signal is stored in the SDRAM.

  Thereafter, the system controller controls the insufficient gain calculation circuit to execute the insufficient gain calculation process. Hereinafter, in this insufficient gain calculation process, first, the system controller outputs the integrated data for each of the 64 divided areas and the pixel count data for one area to the insufficient gain calculation circuit. The deficient gain calculation circuit acquires the integrated data and the pixel number data.

  The luminance data conversion unit calculates luminance data Y (i) based on the integrated value for each RGB, and outputs the luminance data Y (i) to the weighted average processing unit. The weighted average processing unit weights the luminance data Y (i) of each area using the weighting coefficient table shown in the figure, calculates the average value Yk of the luminance data Y (i), and calculates this average. The value Yk is output to the luminance level calculation unit.

  The luminance level calculation unit calculates the luminance level Yp per pixel based on the average value Yk and the number of pixels in one area, and outputs the luminance level Yp per pixel to the insufficient gain calculation unit. The insufficient gain value calculation unit calculates an insufficient gain value (crct_gain) and outputs the insufficient gain value (crct_gain) to the digital signal processing circuit.

  The insufficient gain adjustment unit 82a corrects the insufficient gain by adjusting the gain of the high-resolution image data stored in the SDRAM based on the insufficient gain value (crct_gain).

Thereafter, the system controller controls the digital signal processing circuit to perform various signal processing on the high resolution image data stored in the SDRAM, and controls the compression / decompression processing circuit to compress the image data. Apply processing. Further, the system controller controls the media controller to store the compressed image data in the recording medium and ends the photographing process.

  Next, the configuration of the digital camera 90 according to the third embodiment will be described. A digital camera 90 shown in FIG. 15 includes a digital signal processing circuit 91 and a signal processing parameter calculation circuit 92. As shown in FIG. 16, the digital signal processing circuit 91 includes a gradation conversion unit 93, an outline enhancement processing unit 94, and a noise reduction processing unit 95. These gradation conversion unit 93, contour enhancement processing unit 94, and noise reduction processing unit 95 are based on the photographing sensitivity set by the photographing sensitivity setting unit 61 based on the gradation conversion processing and contour enhancement suitable for the photographing sensitivity. Processing and noise reduction processing are performed on the image data.

  The gradation conversion unit 93 stores conversion tables A and B having different gradation conversion characteristics. One of the conversion tables A and B is selected according to the photographing sensitivity, and gradation conversion processing is performed on the image data. In addition, the contour enhancement processing unit 94 selects a correction amount range according to the photographing sensitivity, and performs contour enhancement processing on the image data. The noise reduction processing unit 95 selects a filter threshold according to the photographing sensitivity, and performs noise reduction processing.

  That is, in the digital signal processing circuit 91, as shown in Table 2 below, gradation conversion processing, contour enhancement processing, and noise reduction processing corresponding to each photographing sensitivity are performed. In the gradation conversion process, if the shooting sensitivity is medium sensitivity and high sensitivity, select the conversion table that shows the normal gradation characteristics and perform the gradation conversion process. If the sensitivity is low, the flash photography at close range is assumed. Therefore, the gradation conversion process is performed by selecting a conversion table having a gradation conversion characteristic for preventing white stripes.

  In the contour emphasis processing, and when the photographing sensitivity is medium sensitivity, normal contour emphasis processing is performed. In addition, when the imaging sensitivity is low, the gain at AMP is small and the influence of noise is small, so the edge emphasis processing is weakened. When the sensitivity is high, the gain at AMP is large and the influence by noise is large. Therefore, the noise reduction process is strengthened as will be described later. For this reason, since the resolution is often impaired, the edge emphasis process is strengthened.

  Further, in the noise reduction processing, when the shooting sensitivity is medium sensitivity, normal noise reduction processing is performed. In addition, since the influence of noise is small when the photographing sensitivity is low, the noise reduction process is reduced. When the sensitivity is high, the influence of noise is large, and thus the noise reduction process is strengthened.

  The signal processing parameter setting circuit 92 is a setting value selection unit that selects a setting value used for performing various kinds of signal processing on image data for each photographing sensitivity. As shown in FIG. 17, the signal processing parameter setting circuit 92 receives photographing sensitivity information. Based on the photographing sensitivity information, the signal processing parameter setting circuit 92 has a gradation conversion characteristic parameter indicating a conversion table used for gradation conversion processing, and a contour. An edge emphasis parameter indicating a correction amount range in the correction process and a noise reduction parameter indicating a filter threshold used for the noise reduction process are determined, and these parameters are output to the digital signal processing circuit 91.

  As shown in FIG. 18, the signal processing parameter setting circuit 92 includes a gradation conversion characteristic selection unit 96, a contour correction amount selection unit 97, and a noise reduction filter selection unit 98. The gradation conversion characteristic selection unit 96 selects one of two conversion tables having different gradation conversion characteristics based on the photographing sensitivity, and outputs a gradation conversion characteristic parameter corresponding to the conversion table. One of the two conversion tables has a gradation conversion characteristic for preventing white stripes, and the other has a normal gradation conversion characteristic.

  Further, the contour correction amount calculation unit 97 selects a correction amount range corresponding to the photographing sensitivity from the three different correction amount ranges shown in FIG. 19 based on the photographing sensitivity, and the contour enhancement parameter corresponding to the correction amount range. Is output. In the graph shown in FIG. 19, the horizontal axis represents the contour enhancement correction amount, and the vertical axis represents the contour enhancement strength.

  In the noise reduction processing, for example, when pixels A1 to A7,... Are arranged as shown in FIG. 20, after extracting the contour component of each pixel, as shown in FIG. Remove the components. Thereafter, the noise component is removed by adding the remaining signal to the original signal. The noise reduction processing unit 95 adjusts the degree of noise reduction by changing the threshold value of the filter. The noise reduction filter selection unit 98 selects one of the three threshold values based on the photographing sensitivity, and outputs a noise reduction parameter corresponding to the threshold value.

  Although the configuration of the digital camera 90 has been described above, other configurations are the same as those of the digital camera 10, and the same components are denoted by the same reference numerals and detailed description thereof is omitted.

  Next, photographing processing of the digital camera 90 having the above configuration will be described with reference to the flowchart of FIG. Since the processing up to exposure control is the same as that of the digital camera 10 according to the first embodiment, the description thereof is omitted. Similar to the digital camera 10, when the exposure control process is performed, the system controller 40 determines whether or not the shutter button 28 has been fully pressed. If it is determined that the button is not fully pressed, the standby state is maintained until the button is fully pressed.

  If it is determined that the shutter button 28 has been fully pressed, the system controller 40 controls the aperture diameter of the aperture 42 and the electronic shutter speed of the CCD 48 based on the exposure value setting, and the flash device 62 emits light. The amount is controlled to cause the CCD 48 to execute an imaging process.

  At this time, the system controller 40 controls the AMP 50b to amplify the imaging signal acquired by the CCD 48 with a gain corresponding to the imaging sensitivity. Thereafter, image data obtained by converting the imaging signal into a digital signal is stored in the SDRAM 54.

  Thereafter, the system controller 40 controls the signal processing parameter setting circuit 92 to execute signal processing parameter setting processing. The signal processing parameter setting circuit 92 determines whether or not the photographing sensitivity is low. When it is determined that the sensitivity is low, the signal processing parameter setting circuit 92 outputs the gradation conversion parameter, the contour enhancement parameter, and the noise reduction parameter corresponding to the low sensitivity to the digital signal processing circuit 91.

  If it is determined that the shooting sensitivity is not low, the signal processing parameter setting circuit 92 determines whether the shooting sensitivity is high. When it is determined that the shooting sensitivity is high, the signal processing parameter setting circuit 92 outputs the gradation conversion parameter, the contour enhancement parameter, and the noise reduction parameter corresponding to the high sensitivity to the digital signal processing circuit 91.

  When it is determined that the photographing sensitivity is not high sensitivity, the signal processing parameter setting circuit 92 outputs the gradation conversion parameter, the contour enhancement parameter, and the noise reduction parameter corresponding to the medium sensitivity to the digital signal processing circuit 91.

  Thereafter, the system controller 40 controls the digital signal processing circuit 91 to execute gradation conversion processing, contour enhancement processing, and noise reduction processing on the high resolution image data stored in the SDRAM 54. At this time, the digital signal processing circuit 91 executes gradation conversion processing, contour enhancement processing, and noise reduction processing corresponding to the photographing sensitivity based on each parameter.

  The digital signal processing circuit 91 performs signal processing such as white balance correction processing and YC conversion processing on the image data in addition to the gradation conversion processing, the contour enhancement processing, and the noise reduction processing.

  Further, the system controller 40 controls the compression / decompression processing circuit 56 to perform compression processing on the image data, and also controls the media controller 58 to transfer the compressed image data to the recording medium 31. The image is stored and the shooting process is terminated.

  In the second and third embodiments, the case where shooting is performed with one shooting sensitivity set has been described as an example. However, the present invention is not limited to this, and the shooting process described in the flowchart of FIG. In addition, shooting may be performed by setting a plurality of shooting sensitivities.

  In the above-described embodiment, the case where the photographing sensitivity is selected from three types of low sensitivity (ISO 400), medium sensitivity (ISO 800), and high sensitivity (ISO 1600) has been described as an example. Or you may select from four or more imaging sensitivity.

  Furthermore, in the above-described embodiment, the focus position detection unit has been described as an example in which the focus position of the focus lens is detected by a contrast method while moving the focus lens. You may detect the focus position of a focus lens using ranging means, such as an active system and a passive system. In this case, distance selection parameters A and B indicating the shooting distance may be used for each zoom position (Z1 to Z10) as shown in Table 3 below instead of the table shown in Table 1 above.

  In the above embodiment, the case where a pulse motor is used as a motor for driving the zoom lens and the focus lens has been described as an example. However, the present invention is not limited to this, and a DC motor may be used. In this case, an encoder may be provided to detect the position of the lens.

  Furthermore, in the above-described embodiment, the case where the light emission amount of the strobe device is controlled based on the subject brightness and the photographing sensitivity has been described as an example. Thus, a light control value that serves as a reference value for stopping the flash emission may be calculated and set.

  In the above embodiment, the case where a CCD image sensor is used as the solid-state imaging device has been described as an example. However, the present invention is not limited to this. For example, a CMOS image sensor may be used.

  Further, although cases have been described with the above embodiment as examples where the present invention is applied to a digital camera, the present invention is not limited to this. For example, the present invention may be applied to a mobile phone with a camera or a digital video camera.

10, 80, 90 Digital camera 13 Shooting lens 40 System controller 41 Zoom lens 43 Focus lens 48 CCD
50b AMP
54 SDRAM
55, 82, 91 Digital signal processing circuit 59 AE detection circuit 60 AF detection circuit 61 Shooting sensitivity setting circuit 62 Strobe device 70 Selection screen 81 Insufficient gain calculation unit 82 Insufficient gain adjustment unit 92 Signal processing parameter setting circuit

Claims (7)

In a photographic device comprising a photographic lens having a zoom lens and a focus lens, a solid-state imaging device that images subject light transmitted through the photographic lens, and a strobe device that emits strobe light toward the subject,
Metering means for metering subject brightness;
Zoom position detecting means for detecting the zoom position of the zoom lens;
A focus position detecting means for detecting a focus position of the focus lens;
Based on the zoom position detected by the zoom position detecting means, the first distance selection parameter on the Far end side and the second distance selection parameter on the Near end side set on the movement range of the focus lens are preliminarily zoomed in positions. When the in-focus position detected by the in-focus position detecting means is closer to the Near end than the second distance selection parameter, the photographing sensitivity is set to a low sensitivity. When the focal position is between the first distance selection parameter and the second distance selection parameter, the photographing sensitivity is set to a medium sensitivity, and the in-focus position is farther than the first distance selection parameter. Shooting sensitivity setting means to set shooting sensitivity to high sensitivity in some cases,
Control means for controlling the exposure and the light emission amount of the strobe device based on the subject brightness measured by the photometry means and the photographing sensitivity set by the photographing sensitivity setting means;
First amplification means for amplifying an imaging signal output from the solid-state imaging device with a gain corresponding to the imaging sensitivity;
An imaging apparatus comprising:   The in-focus position detecting unit extracts a high frequency component from image data obtained by converting the imaging signal into a digital signal for each position of the focus lens, and integrates the high frequency component; and the integration And determining means for determining a position where the integrated value is maximized, and detecting the position where the integrated value is maximized as the in-focus position. Item 1. The photographing apparatus according to Item 1.   The imaging sensitivity setting means sets a plurality of types of the imaging sensitivity, and the control means sets an exposure value corresponding to each imaging sensitivity and performs continuous shooting for the set number of the imaging sensitivity and the exposure value. The photographing apparatus according to claim 1, wherein the photographing apparatus is executed.   A selection screen including display means for displaying an image, wherein the control means controls the display means to select at least one of a plurality of photographed images obtained by the continuous photographing. The photographing apparatus according to claim 3, wherein:   Based on the setting value selected by the setting value selection unit, a setting value selection unit that selects a setting value used when performing various signal processing on the image data, and the image data. 5. The photographing apparatus according to claim 2, further comprising: a signal processing unit that applies the various signals to the camera.   The set value is a parameter for specifying a gradation conversion characteristic used when performing gradation conversion processing on the image data, a parameter for specifying a correction amount range when performing edge enhancement processing on the image data, The imaging apparatus according to claim 5, wherein the parameter is a parameter that specifies a threshold value of a filter used when noise reduction processing is performed on the image data. In an exposure control method for an imaging apparatus comprising: a photographic lens having a zoom lens and a focus lens; a solid-state imaging device that images subject light that has passed through the photographic lens; and a strobe device that emits strobe light toward the subject.
Measure subject brightness,
Detecting the zoom position of the zoom lens;
Detecting the in-focus position of the focus lens;
Based on the zoom position, a Far end side first distance selection parameter and a Near end side second distance selection parameter set on the movement range of the focus lens are selected from values set in advance for each zoom position. When the in-focus position is closer to the Near end than the second distance selection parameter, the photographing sensitivity is set to a low sensitivity, and the in-focus position is the first distance selection parameter and the second distance selection. When it is between the parameters, the shooting sensitivity is set to medium sensitivity, and when the in-focus position is far from the first distance selection parameter, the shooting sensitivity is set to high sensitivity.
Based on the subject brightness and the shooting sensitivity, control the exposure and the light emission amount of the strobe device,
An exposure control method, comprising: amplifying an imaging signal output from the solid-state imaging device with a gain corresponding to the imaging sensitivity.

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