JP2006310971A - Imaging apparatus, exposure control method, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a flicker noise effectively and secure a necessary hysteresis amount, while maintaining a required frame rate at the time of imaging a moving image. <P>SOLUTION: The lower limit of a shutter speed is set to a first speed value (1/32 sec) determined corresponding to the frame rate required for the moving image, and the upper limit is set to a second speed value (1/128 sec) determined corresponding to the frequency of an external light source having a flickering characteristic. At the time of imaging the moving image, the shutter speed is adjusted preferentially within the above specified range, and when the shutter speed is to exceed the specified range, exposure control is performed by adjusting other imaging parameters. By this, it becomes possible to reduce the flicker noise effectively, and to secure the necessary hysteresis amount, while maintaining the required frame rate at the time of imaging the moving image. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an imaging device such as a digital camera having an automatic exposure function, and an exposure control method and program used in the imaging device.

  Some digital cameras have an automatic exposure function that determines shooting parameters such as shutter speed and aperture according to the brightness of the subject. This automatic exposure function predefines how to change a plurality of shooting parameters according to the detected brightness of the subject. Note that an exposure diagram is used to represent the movement of the imaging parameter according to this rule, and the movement according to this exposure diagram is called a diagram operation.

  By the way, even if the brightness of the subject is constant when viewed in a long time, it continuously fluctuates when viewed in a short time. For example, when a diaphragm with a mechanical action is caused to follow such a short-time luminance fluctuation, a mechanical sound is generated each time the diaphragm is switched, and this is particularly affected when shooting moving images with sound. give.

  Thus, a technique is known in which the shutter speed is changed as a shooting parameter that does not involve a mechanical operation for a short-time luminance fluctuation (see, for example, Patent Document 1). At this time, a hysteresis amount is used as an index indicating how much brightness fluctuation can be absorbed. The larger the hysteresis amount is, the more the number of times of changing the aperture can be reduced, and it is desirable that it is at least one level (double brightness) in terms of EV value (exposure value).

  On the other hand, under a fluorescent lamp that blinks with a commercial power supply, flicker noise occurs in the captured image due to the relationship between the power supply frequency and the exposure timing, and there is a problem that affects the display of a through image and the recording of a moving image. Conventionally, in order to reduce such flicker noise, a technique for fixing a shutter speed to a power supply frequency is known (see, for example, Patent Document 2).

Further, at the time of moving image shooting, a frame rate of 30 frames or more is generally applied in order to ensure smoothness as a moving image. The exposure time per frame, that is, the shutter speed is limited by this frame rate, and it is necessary to set it to 1/30 second or less for 30 frames per second.
JP 2004-56699 A JP 2003-189172 A

  However, the technique of fixing the shutter speed as in Patent Document 2 can reduce flicker noise caused by the power supply frequency of the fluorescent lamp, but has a problem that a sufficient amount of hysteresis cannot be secured. Further, the technique of changing the shutter speed as in Patent Document 1 can secure a necessary amount of hysteresis, but has a problem that flicker noise frequently occurs.

  An object of the present invention is to achieve both reduction of flicker noise and securing of a necessary amount of hysteresis, and further reduce flicker noise more effectively while maintaining a required frame rate during moving image shooting. It is another object of the present invention to provide an imaging apparatus, an exposure control method, and a program that can ensure a necessary amount of hysteresis.

  An image pickup apparatus according to claim 1 of the present invention is an image pickup apparatus capable of recording or displaying image data continuously obtained from an image pickup device as a moving image, measuring means for measuring the brightness of a subject, and the measurement Determining means for determining a plurality of shooting parameters including the shutter speed based on the brightness of the subject measured by the means; and a first lower limit value of the shutter speed determined in accordance with a frame rate required for the moving image. First definition means for determining a speed value of the second, second specification means for determining an upper limit value of the shutter speed as a second speed value determined in correspondence with a frequency of an external light source having a blinking characteristic, When the values of various shooting parameters determined by the determination unit are adjusted according to the brightness of the subject that is sequentially measured by the measurement unit during recording or display, the shading is performed. Exposure control means for preferentially adjusting the shutter speed and adjusting the other shooting parameters when the shutter speed exceeds the range defined by the first and second defining means. It is characterized by that.

  According to such a configuration, when adjusting the values of various shooting parameters in accordance with the brightness of the subject, the shutter speed is preferentially adjusted within a predetermined range. Exposure control is performed by adjusting the shooting parameters. The lower limit value of the specified range is determined as a first speed value determined corresponding to the frame rate necessary for the moving image, and the upper limit value is determined corresponding to the frequency of the external light source having the blinking characteristic. Accordingly, in moving image shooting (including through image display), it is possible to achieve both reduction of flicker noise and securing of a necessary hysteresis amount while maintaining a frame rate for smooth moving image display.

  According to a second aspect of the present invention, there is provided the imaging apparatus according to the first aspect, further comprising amplification factor control means for controlling an amplification factor of the signal output from the imaging element, wherein the various imaging parameters are the amplification factor. Including the amplification factor by the control means, and the exposure control means adjusts the values of the various shooting parameters determined by the determination means according to the brightness of the subject sequentially measured by the measurement means. In addition, the amplification factor is preferentially adjusted.

  According to such a configuration, the amount of hysteresis is increased by adjusting the exposure together with the shutter speed together with an amplification factor that is less adversely affected by fluctuations compared to other shooting parameters, even when only the shutter speed is used. be able to.

  According to a third aspect of the present invention, in the imaging apparatus according to the second aspect, the exposure control unit adjusts the maximum value of the amplification factor by limiting it to a predetermined value.

  According to such a configuration, the influence of image quality is generally small if the amplification factor is equal to or less than a predetermined value, but there is an adverse effect that the influence of noise increases when the amplification factor is high. When this amplification factor is preferentially adjusted, the influence of noise can be reduced by limiting the maximum value to a predetermined value.

  According to a fourth aspect of the present invention, in the imaging apparatus according to the second aspect, the exposure control unit adjusts the shutter speed to increase the exposure value when the exposure value is caused to follow in the direction of decreasing the exposure value. The amplification factor is adjusted in the case of following the control.

  According to such a configuration, the two shooting parameters are set according to the direction of hysteresis, such as the shutter speed when tracking the exposure value in the direction of darkening, and the amplification factor when tracking the exposure value in the direction of brightening. By using properly, the amount of hysteresis can be doubled compared to the case of adjusting only by the shutter speed.

  According to a fifth aspect of the present invention, in the imaging apparatus according to the second aspect, the exposure control unit adjusts each of the shutter speed and the amplification factor simultaneously or alternately in a minimum unit that can be adjusted. Features.

  According to such a configuration, when the shooting parameter to be preferentially adjusted is the shutter speed and the amplification factor, the adjustment is performed only by the shutter speed by simultaneously or alternately adjusting these minimum adjustable units. The amount of hysteresis can be doubled.

  According to a sixth aspect of the present invention, there is provided the image pickup apparatus according to the first aspect, further comprising pixel addition processing means for adding data of each pixel of the image pickup device at a predetermined magnification, Including a pixel addition magnification by pixel addition processing means, wherein the exposure control means adjusts the pixel addition magnification when the shutter speed exceeds a range defined by the first and second defining means. To do.

  According to such a configuration, when adjusting the shooting parameters other than the shooting parameters to be preferentially adjusted, the pixel addition magnification with a relatively small image quality degradation is used, thereby minimizing the decrease in resolution due to the pixel addition magnification. Can be suppressed.

  According to a seventh aspect of the present invention, in the imaging apparatus according to the first aspect, pixel addition processing means for adding data of each pixel of the imaging element at a predetermined magnification, and a light amount incident on the imaging element And the various imaging parameters include a pixel addition magnification by the pixel addition processing unit and a number of filter stages by the optical filter unit, and the exposure control unit has the shutter speed set to Determining means for determining the brightness of the subject when the range exceeds the range defined by the first and second defining means; and if the brightness of the subject is within a predetermined brightness range by the determining means, And a parameter changing unit that adjusts the pixel addition magnification and adjusts the number of filter stages when the brightness of the subject is brighter than the predetermined brightness. And wherein the Rukoto.

  According to such a configuration, by using only when the subject is relatively bright, it is possible to maintain high image quality over a wide exposure range, and it is also possible to cope with a case where the subject is very bright. .

  According to an eighth aspect of the present invention, in the imaging apparatus according to the first aspect, pixel addition processing means for adding data of each pixel of the imaging element at a predetermined magnification, and a signal output from the imaging element Gain control means for controlling the amplification factor, and the various imaging parameters include a pixel addition magnification by the pixel addition processing means and an amplification factor by the amplification control means, and the exposure control means is the shutter speed. Determining means for determining the brightness of the subject when the brightness exceeds the range defined by the first and second defining means, and if the brightness of the subject is within the predetermined brightness range by the determining means Parameter changing means for adjusting the pixel addition magnification and adjusting the amplification factor when the brightness of the subject is darker than the predetermined brightness. That.

  According to such a configuration, only when the subject is relatively dark, if the amplification factor is adjusted beyond the specified range, high image quality can be maintained over a wide exposure range, and even when the subject is very dark. Can respond.

  According to a ninth aspect of the present invention, in the imaging apparatus according to the first aspect, the image pickup apparatus further includes mode setting means for setting a special mode, and the exposure control means is configured such that the special mode is set by the mode setting means. In addition, the shutter speed is preferentially adjusted within the specified range, and when the shutter speed exceeds the specified range, other shooting parameters are adjusted to perform exposure control.

  According to such a configuration, exposure control is performed to achieve both reduction of flicker noise and securing of a necessary amount of hysteresis while maintaining the moving image frame rate by setting the special mode.

  According to a tenth aspect of the present invention, there is provided the imaging apparatus according to the first aspect, further comprising mode setting means for selectively setting a first special mode and a second special mode, wherein the first and second special modes are provided. The defining means sets a specified range giving priority to the hysteresis amount when the first special mode is set by the mode setting means, and prioritizes flicker removal when the second special mode is set. A prescribed range is set, and the exposure control means preferentially adjusts the shutter speed within the prescribed range set according to the first or second special mode, and the shutter speed exceeds the prescribed range. The exposure control is performed by adjusting other shooting parameters.

  According to this configuration, exposure control is performed with priority given to the hysteresis amount by setting the first special mode, and exposure control is performed with priority given to flicker removal by setting the second special mode.

  An exposure control method according to an eleventh aspect of the present invention is an exposure control method used for an imaging apparatus capable of recording or displaying image data continuously obtained from an imaging device as a moving image, and measuring the brightness of a subject. A step of determining a plurality of shooting parameters including a shutter speed based on the measured brightness of the subject, and determining a lower limit value of the shutter speed corresponding to a frame rate required for the moving image. A step of setting a first speed value, a step of setting an upper limit value of the shutter speed to a second speed value determined corresponding to the frequency of an external light source having a blinking characteristic, and during recording or display of a moving image, When adjusting the values of the various shooting parameters according to the brightness of the subject that is sequentially measured, the shutter speed is preferentially adjusted, and the shutter speed is adjusted. There characterized in that it comprises a step of performing exposure control by adjusting the other imaging parameters to exceed the range defined by said first and second speed values.

  According to such an exposure control method, the same effects as those of the first aspect of the present invention can be achieved by executing the processing according to each step.

  A program according to claim 12 of the present invention is a program executed by a computer mounted on an imaging apparatus capable of recording or displaying image data continuously obtained from an imaging element as a moving image, and A function for measuring the brightness of the subject, a function for determining a plurality of shooting parameters including the shutter speed based on the measured brightness of the subject, and setting the lower limit of the shutter speed to a frame rate necessary for the moving image. A function for determining a first speed value determined correspondingly, a function for determining an upper limit value of the shutter speed to a second speed value determined corresponding to the frequency of an external light source having blinking characteristics, When adjusting the values of the various shooting parameters according to the brightness of the subject that is sequentially measured during recording or display, the shutter speed is increased. Adjustable, and is characterized in that to realize the function of performing exposure control by adjusting the other imaging parameters when the shutter speed is outside the range defined by the first and second speed values.

  Therefore, when the computer executes the program for realizing each function, the same effects as those of the first aspect of the invention can be achieved.

  According to the present invention, it is defined by the first speed value determined corresponding to the frame rate required for the moving image and the second speed value determined corresponding to the frequency of the external light source having the blinking characteristic. By adjusting the shutter speed preferentially within the specified range and performing exposure control by adjusting other shooting parameters when the specified range is exceeded, flicker is more effectively maintained while maintaining the required frame rate during movie shooting. Noise can be reduced and a necessary amount of hysteresis can be secured.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing an external configuration when a digital camera is taken as an example of an imaging apparatus according to an embodiment of the present invention. FIG. 1 (a) is mainly a front configuration, and FIG. It is a perspective view which shows the structure of a back surface.

  The digital camera 1 has a photographing lens 3, a self-timer lamp 4, an optical finder window 5, a strobe light emitting unit 6, a microphone unit 7 and the like on the front surface of a substantially rectangular thin plate-like body 2 on the upper surface (for the user). On the right end side, a power key 8 and a shutter key 9 are provided.

  The power key 8 is a key operated every time the power is turned on / off, and the shutter key 9 is a key for instructing a photographing timing at the time of photographing.

  Also, on the back of the digital camera 1, a shooting mode (R) key 10, a playback mode (P) key 11, an optical viewfinder 12, a speaker unit 13, a macro key 14, a strobe key 15, a menu (MENU) key 16, a ring A key 17, a set (SET) key 18, a display unit 19, and the like are provided.

  The shooting mode key 10 is operated automatically from the power-off state to automatically turn on the power and shift to the still image shooting mode. On the other hand, by repeatedly operating from the power-on state, the still image mode and the moving image mode are switched. Set cyclically. The still image mode is a mode for photographing a still image. The moving image mode is a mode for shooting a moving image.

  The shutter key 9 is commonly used for these photographing modes. That is, in the still image mode, a still image is taken at the timing when the shutter key 9 is pressed. In the moving image mode, shooting of a moving image is started at a timing when the shutter key 9 is pressed, and shooting of the moving image is ended when the shutter key 9 is pressed again.

  When the playback mode key 11 is operated from the power-off state, the playback mode key 11 is automatically turned on to enter the playback mode.

  The macro key 14 is operated when switching between normal shooting and macro shooting in the still image shooting mode. The strobe key 15 is operated when switching the light emission mode of the strobe light emitting unit 6. The menu key 16 is operated when selecting various menu items. The ring key 17 is integrally formed with item selection keys in the up, down, left, and right directions, and the set key 18 located in the center of the ring key 17 sets the item selected at that time. To operate.

  The display unit 19 is composed of a color liquid crystal panel with a backlight, and displays a through image on the monitor as an electronic viewfinder in the photographing mode, and reproduces and displays the selected image and the like in the reproduction mode.

  Further, the digital camera 1 is provided with an optical zoom function, and the enlargement ratio of the image can be changed by physically changing the focal length by operating the zoom keys 20a and 20b. Of the zoom keys 20a and 20b, one zoom key 20a is for the telephoto end and is used when the zoom magnification is changed to the telephoto side. The other zoom key 20b is for the wide end and is used when the zoom magnification is changed to the wide angle side.

  Although not shown, the digital camera 1 has a memory card slot for attaching / detaching a memory card used as a recording medium, a serial interface connector for connecting to an external personal computer, etc., for example, USB (Universal). Serial Bus) connector and the like are provided.

  FIG. 2 is a block diagram showing an electronic circuit configuration of the digital camera 1.

  In the digital camera 1, a lens optical system 22 including a focus lens and a zoom lens (not shown) constituting the photographing lens 3 is provided so as to be movable within a predetermined range in the optical axis direction by driving a motor 21. . A CCD (charge coupled device) 25, which is an image sensor, is disposed behind the lens optical system 22 via a filter mechanism 23 and a diaphragm mechanism 24.

  The filter mechanism 23 optically adjusts the amount of light incident on the CCD 25 via the lens optical system 22 by switching the number of stages of an optical filter called “ND filter”. The diaphragm mechanism 24 adjusts the amount of light incident on the CCD 25 via the lens optical system 22 by switching the diaphragm value (F value). The CCD 25 receives light from each part of the subject input through the aperture mechanism 24 and outputs an electrical signal corresponding to the intensity of the light.

  In the recording mode, which is the basic mode, the CCD 25 is scanned and driven by a timing generator (TG) 26 and a driver 27, and outputs a photoelectric conversion output corresponding to a light image formed at fixed intervals for one screen. The photoelectric conversion output of the CCD 25 is appropriately gain-adjusted by an AGC circuit (automatic gain control circuit) 28 for each primary color component of RGB in the state of an analog value signal, and then sample-held by a sample-hold circuit 29. It is converted into digital data by the D converter 30.

  Then, the image processing circuit 31 performs image processing including pixel interpolation processing and γ correction processing to generate a digital luminance signal Y and color difference signals U and V (Cb, Cr), and DMA (Direct Memory Access). ) Is output to the controller 32.

  The DMA controller 32 once uses the luminance signal Y and the color difference signals U and V output from the image processing circuit 31 by using the composite synchronization signal, the memory write enable signal, and the clock signal from the image processing circuit 31 once. And the DMA transfer to the DRAM 34 used as a buffer memory through the DRAM interface (I / F) 33.

  In the present embodiment, the CCD 25 includes a pixel addition processing unit 25a. The pixel addition processing unit 25a outputs the charge amount accumulated for each pixel inside the CCD 25 to the outside of the CCD 25 after adding the charge amounts of a plurality of pixels at a predetermined magnification. During through image display and moving image shooting, the required resolution is lower than during still image shooting, and the number of pixels that need to be read out from the CCD 25 is reduced. At this time, instead of simply decimating and outputting the pixels, By adding and outputting pixels inside the CCD 25, the amount of light can be increased without increasing the readout time.

  The control unit 35 controls the entire digital camera 1 and is constituted by a microcomputer including a CPU, a ROM storing an operation program executed by the CPU, a RAM used as a work memory, and the like. Is done. The control unit 35 is provided with an exposure control processing unit 35a that performs exposure control by changing various shooting parameters including a shutter speed in accordance with the brightness of the subject.

  Here, after the DMA transfer of the luminance and color difference signals to the DRAM 34 is completed, the control unit 35 reads the luminance and color difference signals from the DRAM 34 via the DRAM interface 33 and writes them to the VRAM 38 via the VRAM controller 37.

  The digital video encoder 39 periodically reads out the luminance and color difference signals from the VRAM 38 via the VRAM controller 37, generates a video signal based on these data, and outputs the video signal to the display unit 19.

  The display unit 19 functions as a monitor display unit (electronic finder) at the time of shooting as described above. By displaying based on the video signal from the digital video encoder 39, the display unit 19 captures from the VRAM controller 37 at that time. An image based on the image information is displayed in real time.

  As described above, when the image at that time is displayed in real time as the monitor image on the display unit 19, for example, when the shutter key 9 is pressed at a timing at which still image shooting is desired, a trigger signal is generated.

  In addition to the shutter key 9 described above, the key input unit 36 includes a power key 8, a shooting mode key 10, a playback mode key 11, a macro key 14, a strobe key 15, a menu key 16, a ring key 17, and a set key 18. , Zoom keys 20a, 20b, etc., and signals accompanying these key operations are sent directly to the control unit 35.

  In response to the trigger signal, the control unit 35 immediately stops the path from the CCD 25 to the DRAM 34 after completion of the DMA transfer of the luminance and color difference signals for one screen captured from the CCD 25 to the DRAM 34 at that time. , Transition to the record storage state.

  In this recording and storage state, the control unit 35 transmits the luminance and color difference signals for one frame written in the DRAM 34 to each of Y, Cb, and Cr components of 8 pixels by 8 pixels by the DRAM interface 33. The data is read out in units called basic blocks and written in a JPEG (Joint Photographic Coding Experts Group) circuit 40. In this JPEG circuit 40, an ADCT (Adaptive Discrete Cosine Transform) is an entropy coding system. Data compression is performed by processing such as conversion.

  The obtained code data is read out from the JPEG circuit 40 as a data file of one image and written in the memory 41 for recording. The memory 41 includes, in addition to an internal memory such as a flash memory built in the main body in advance, a memory card that is detachably mounted as a recording medium. With the compression processing of the luminance and color difference signals for one frame and the completion of writing all the compressed data to the memory 41, the control unit 35 activates the path from the CCD 25 to the DRAM 34 again.

  The control unit 35 is further connected with an audio processing unit 42, a USB interface (I / F) 43, and a strobe driving unit 44.

  The audio processing unit 42 includes a sound source circuit such as a PCM sound source, and digitizes the audio signal input from the microphone unit (MIC) 7 when recording audio, and a predetermined data file format such as MP3 (MPEG-1 audio layer). 3) While compressing the data according to the standard, an audio data file is created and sent to the memory 41. On the other hand, when reproducing the audio, the audio data file read from the memory 41 is uncompressed and converted into an analog signal. The sound is output through a speaker unit (SP) 13 provided on the back side.

  The USB interface 43 performs communication control when image data and other information are transmitted / received to / from another information terminal device such as a personal computer connected by wire via a USB connector. The strobe driving unit 44 charges a large-capacitance capacitor for strobe (not shown) at the time of photographing, and then drives the strobe light emitting unit 6 to flash based on the control from the control unit 35.

  Further, when shooting a moving image instead of a still image, when the shutter key 9 is pressed, the above-described JPEG circuit 40 compresses the captured moving image using a technique such as motion-JPEG (Joint Photographic Experts Group). To the memory 41. When the shutter key 9 is operated again, the recording of the moving image data is finished.

  On the other hand, in the playback mode which is the basic mode, the control unit 35 selectively reads out the image data recorded in the memory 41 and is compressed by a procedure completely opposite to the procedure in which the data is compressed by the JPEG circuit 40 in the recording mode. Decompress image data. The decompressed image data is held in the DRAM 34 via the DRAM interface 33, and then the content held in the DRAM 34 is stored in the VRAM 38 via the VRAM controller 37. The image data is periodically read out from the VRAM 38. A video signal is generated and reproduced and output by the display unit 19.

  If the selected image data is not a still image but a moving image, the multiple frames of still image data that make up the moving image data are played back and displayed sequentially in chronological order, and all the still image data is played back. For example, the top still image data is displayed until the next playback instruction is given.

  FIG. 3 is a diagram for explaining the relationship between the shutter speed of the digital camera 1 and flicker.

  In general, the brightness of a fluorescent lamp installed as indoor lighting fluctuates at a cycle twice the power supply frequency. That is, as shown in FIGS. 3A and 3B, the blinking is repeated at a cycle of 100 Hz with a power source of 50 Hz (East Japan) and 120 Hz with a power source of 60 Hz (Western Japan). When shooting a movie under a fluorescent lamp with such flickering characteristics, flicker (flicker) occurs in the shot image due to the relationship between the power cycle and the exposure time determined by the shutter speed. May have an effect.

  That is, as shown in FIG. 3C, when a moving image is taken at a shutter speed of 1/512 seconds, for example, the exposure point is obtained at each exposure point due to a deviation between the exposure timing and the light peak that fluctuates depending on the power cycle. The amount of light is different. In FIGS. 3A and 3B, the larger the area of the hatched portion, the greater the amount of light. Conversely, the smaller the area of the shaded portion, the smaller the amount of light. This difference in the amount of light appears as flicker.

  In this case, for example, if exposure is performed at 20 frames per second, which is the least common multiple of the power cycle, the timing of exposure is synchronized with the power cycle, so that the flicker phenomenon can be suppressed. However, at 20 frames per second, there is a problem of lack of smoothness as a moving image. Generally, when shooting moving images, a frame rate of 30 frames or more per second is required.

  As another method, there is a method of extending the exposure time by slowing the shutter speed. That is, as shown in FIGS. 3D and 3E, if the exposure time is increased by slowing down the shutter speed, a lot of light peaks that fluctuate depending on the power supply cycle are included. No longer occurs. However, if the shutter speed is decreased, there is a problem that the moving image frame rate cannot be secured.

  The exposure operation by the digital camera 1 having the above configuration will be described below.

  FIG. 4 is a diagram (exposure diagram) showing an exposure operation by the digital camera 1, and shows a correspondence relationship between EV values (Exposure Value) and various shooting parameters including a shutter speed when ISO 100 is used. . Note that shooting parameters other than the shutter speed include ND filter, aperture, pixel addition, and amplification factor.

  When shooting a movie under a fluorescent lamp, a special mode called “flicker removal mode” is set by, for example, operating the menu key 16 with the movie mode set by pressing the shooting mode key 10 shown in FIG. To do.

  In this “flicker removal mode”, as shown in FIG. 4, the lower limit value of the shutter speed is set to 1/32 seconds (first speed value), and the upper limit value is set to 1/128 seconds (second speed value). . The lower limit of 1/32 seconds (first velocity value) corresponds to a frame rate of 30 frames required for moving images. The upper limit value 1/128 seconds (second speed value) corresponds to the power supply frequency of the fluorescent lamp having the blinking characteristic.

  Here, when the optimum exposure value, that is, the EV value according to the brightness of the subject is determined, the shutter speed is preferentially adjusted within the specified range according to the exposure diagram of FIG. In this case, the adjustment by the shutter speed (electronic shutter) may be considered to be stepless, and is finely adjusted between 1/32 seconds and 1/128 seconds, which is the specified range.

  On the other hand, when the change in the brightness of the subject exceeds the specified range, the exposure is adjusted by other shooting parameters other than the shutter speed. The other imaging parameters referred to here are amplification factor, pixel addition, aperture (F value), and ND filter.

  As shown in FIG. 2, the adjustment by the amplification factor is performed by controlling the amplification factor (gain) of the output signal of the CCD 25 by the AGC circuit 28. In the example of FIG. 4, adjustment is possible between 0 and +18 dB.

  As shown in FIG. 2, the adjustment by pixel addition is performed by changing the magnification at which data of each pixel is added by the pixel addition processing unit 25 a provided in the image processing circuit 31. In the example of FIG. 4, adjustment is possible in three stages of none, double, and quadruple.

  Adjustment by the diaphragm (F value) is performed by mechanically adjusting the amount of light incident on the CCD 25 through the lens optical system 22 by a diaphragm mechanism 24 as shown in FIG. In the example of FIG. 4, adjustment is possible in two stages of F2.8 and F4.0.

  The adjustment by the ND filter is performed by switching the number of stages of the ND filter by the filter mechanism 23 as shown in FIG. In the example of FIG. 4, the adjustment can be performed in two stages, that is, none and one stage. In the case of no ND filter, the ND filter is separated from the optical axis by the filter mechanism 23, and in the case of one stage, the ND filter is driven to be positioned on the optical axis.

  However, when these imaging parameters are used, for example, in the adjustment based on the amplification factor, there is a problem that if the amplification factor is increased to a predetermined value or more, the influence of noise increases. The adjustment by the aperture is accompanied by a mechanical operation such as “clicking” at the time of switching the aperture, and thus becomes a problem particularly when shooting moving images with sound. The adjustment by the ND filter has a problem that the image quality deteriorates because light is blocked by the optical lens. In addition, in the adjustment by pixel addition, although not as much as the above-described shooting parameters, the image quality slightly changes depending on the addition magnification. Therefore, there is a problem that flickering occurs when the addition magnification is frequently switched.

  For this reason, when adjusting the exposure with the shooting parameters other than the shutter speed, it is preferable to use them selectively in the order in which the respective characteristics are taken into consideration. That is, as shown in FIG. 4, when the amount of light is reduced, that is, when the exposure value is made to follow a brighter direction, the adjustment can be made in the order of amplification factor → pixel addition → aperture (F value) → ND filter. preferable. Conversely, when increasing the amount of light, that is, when making the exposure value follow in a dark direction, it is preferable to adjust in the order of ND filter → aperture (F value) → pixel addition → amplification factor.

  When the subject is extremely bright and the EV value is 11 or more, the shutter speed is adjusted beyond the specified range.

  Here, in order to facilitate understanding, a specific description will be given focusing on the aperture (F value).

  FIG. 5 is a diagram partially showing a diagram operation in the vicinity of switching of the aperture (F value) in the exposure diagram. It is assumed that the aperture (F value) takes two values of F2.8 and F4.0 during moving image recording or through display.

  For example, when the aperture is set to F2.8 and the brightness of the subject becomes brighter than EV10, the aperture is switched to F4.0. Conversely, when the brightness of the subject is darker than EV9 with the aperture set to F4.0, the aperture is switched to the open side, that is, F2.8.

  Here, an adjustment based on the shutter speed is performed at an intermediate point of the aperture F value, for example, in the vicinity of EV9.5. That is, for example, when the aperture is changed from EV9 to EV10 in a state where the aperture is F2.8, the shutter speed is gradually increased, and when the aperture reaches 1/128 which is the upper limit value of the specified range, the aperture is set to F4.0. And the shutter speed is returned to 1/64. Conversely, when changing from EV10 to EV9 with the aperture set to F4.0, the shutter speed is gradually decreased, and when the aperture reaches 1/32 which is the lower limit value of the specified range, the aperture is set to F2.8. And the shutter speed is returned to 1/64. Thereby, exposure control can be performed while securing a hysteresis amount of 1 EV from EV9 to EV10.

  Thus, it is defined by the first speed value determined corresponding to the frame rate necessary for the moving image and the second speed value determined corresponding to the power supply frequency of the fluorescent lamp having the blinking characteristic. By preferentially adjusting the shutter speed within the range, flicker noise can be reduced and a necessary amount of hysteresis can be secured while maintaining a required frame rate during moving image shooting.

  Here, the upper limit value of the shutter speed is set to 1/128 seconds in order to secure a one-step hysteresis amount in terms of EV value. However, if priority is given to the reduction of flicker over the hysteresis amount, the shutter speed is set. May be set to 1/64 second to reduce the amount of hysteresis in half. In this case, as will be described later, if the adjustment of the amplification factor is used together with the shutter speed (see FIGS. 6 and 7), the upper limit value of the shutter speed can be set to 1/64 seconds and the hysteresis amount can be secured by 1 EV. .

  Further, although described as the moving image shooting operation, the same operation is performed for the through image display during standby for still image shooting, and the same effect can be obtained.

  Next, as another exposure operation by the digital camera 1, a case where the gain is preferentially adjusted in addition to the shutter speed will be described.

  FIG. 6 is a diagram (exposure diagram) showing another exposure operation by the digital camera 1, and shows an exposure operation when the gain is preferentially adjusted in addition to the shutter speed.

  In a state where the moving image mode is set by pressing the shooting mode key 10 shown in FIG. 1, a special mode called “flicker removal mode” is set by operating the menu key 16, for example.

  With the setting of the “flicker removal mode”, the lower limit value of the shutter speed is set to 1/32 seconds (first speed value), and the upper limit value is set to 1/64 seconds (second speed value). As described above, 1/32 seconds (first velocity value) of the lower limit corresponds to a frame rate of 30 frames required for moving images, and 1/64 seconds (second velocity value) of the upper limit is fluorescent. Although it corresponds to the power frequency of the lamp, the upper limit value is set lower than the exposure diagram of FIG. Further, the gain adjustment range is set to 0 dB to +6 dB in correspondence with the shutter speed adjustment range.

  In such a configuration, when the shutter key 9 is pressed, moving image shooting is started. At that time, the brightness of the subject is measured from the amount of light incident on the CCD 25 through the lens optical system 22, and an optimum exposure corresponding to the brightness of the subject is performed by an exposure control processing unit 35 a provided in the control unit 35. A value or EV value is determined. Then, in order to match this EV value, the shutter speed and the amplification factor are preferentially adjusted according to the exposure diagram of FIG.

  In this case, when adjusting in the direction of darkening (that is, when the EV value is higher than the previous time), the shutter speed is adjusted within the specified range as in FIG. 5, but when adjusting in the direction of brightening. In other words, when the EV value is lower than the previous time, the amplification factor is adjusted within a specified range.

  That is, a specific description will be given focusing on the vicinity of the aperture switching. For example, when the aperture is changed from EV8 to EV9 in the state of F2.8, the shutter speed is gradually increased, and the upper limit value of the specified range is set. When 1/64 is reached, the aperture is switched to F4.0 and the shutter speed is returned to 1/32. Conversely, when changing from EV9 to EV8 with the aperture at F4.0, the gain is gradually increased with the shutter speed left unchanged. In this case, when the amplification factor reaches +6 dB, the aperture is switched to F2.8 and the amplification factor is returned to 0 db. The reason why the maximum value of the amplification factor is limited to +6 dB is that when the amplification factor is further increased, the image quality is significantly deteriorated due to the influence of noise.

  Further, when the change in the brightness of the subject exceeds the specified range, adjustment is performed by other shooting parameters than the shutter speed. As described above, the other imaging parameters are the amplification factor, pixel addition, aperture (F value), and ND filter, and exposure control is performed by appropriately adjusting these according to the brightness of the subject.

  When the absolute value of the brightness of the subject falls outside the range of 5 to 11 in terms of EV value, the shutter speed and amplification factor are adjusted beyond the specified range.

  In this way, by properly using the two shooting parameters according to the direction of hysteresis, such as the shutter speed when tracking the exposure value in the darkening direction and the amplification factor when tracking the exposure value in the brightening direction, The amount of hysteresis can be doubled as compared with the case of adjusting only by the shutter speed as shown in FIG. In this case, as shown in FIG. 6, the amount of hysteresis is 2 EV.

  In the example of FIG. 6, the shooting parameter to be preferentially adjusted is selectively used depending on the shutter speed and amplification factor according to the hysteresis direction. However, the present invention is not limited to this, and the shutter speed is not necessarily limited to the hysteresis direction. It is also possible to use both the amplification factor and the amplification factor.

This is shown in FIG.
FIG. 7 is a diagram (exposure diagram) showing another exposure operation by the digital camera 1, and shows the exposure operation when adjusting the shutter speed and the amplification factor simultaneously.

  As the “flicker removal mode” is set, the lower limit value of the shutter speed is set to 1/32 seconds (first speed value) and the upper limit value is set to 1/64 seconds (second speed value). As described above, 1/32 seconds (first velocity value) of the lower limit corresponds to a frame rate of 30 frames required for moving images, and 1/64 seconds (second velocity value) of the upper limit is fluorescent. It corresponds to the power frequency of the lamp. Further, the adjustment range of the amplification factor is set to 0 dB to +6 dB in correspondence with the adjustment range of the shutter speed.

  Here, the difference from FIG. 6 is that both the shutter speed and the amplification factor are used to secure the same hysteresis amount, that is, 2 EV when adjusting in the darkening direction and adjusting in the brightening direction. is there.

  Specifically, for example, when changing the aperture from EV8 to EV9 in a state where the aperture is F2.8, the shutter speed is gradually increased and the amplification factor is gradually decreased. Go. In this case, the shutter speed and the amplification factor are adjusted simultaneously or alternately in the smallest adjustable unit so as to be the same as the EV value obtained by adjusting only the shutter speed in FIG. When both the shutter speed and the amplification factor reach 1/64, 0 db which is the upper limit value of the specified range, the aperture is switched to F4.0 and the shutter speed and the amplification factor are returned to 1/48, +3 db.

  Conversely, when changing from EV9 to EV8 with the aperture at F4.0, the gain is gradually increased while the shutter speed is gradually decreased. Also in this case, the shutter speed and the amplification factor are adjusted simultaneously or alternately in the smallest adjustable unit so as to be the same as the EV value obtained by adjusting only the amplification factor in FIG. When both the shutter speed and the amplification factor reach 1/32, +6 dB which is the lower limit value of the specified range, the aperture is switched to F2.8 and the shutter speed and the amplification factor are returned to 1/48, +3 db.

  Further, when the change in the brightness of the subject exceeds the specified range, adjustment is performed by other shooting parameters than the shutter speed. As described above, the other imaging parameters are the amplification factor, pixel addition, aperture (F value), and ND filter, and exposure control is performed by appropriately adjusting these according to the brightness of the subject.

  When the absolute value of the brightness of the subject falls outside the range of 5 to 11 in terms of EV value, the shutter speed and amplification factor are adjusted beyond the specified range.

  As described above, the exposure control can be performed while securing the necessary hysteresis amount as described above by adjusting each of the shutter speed and the amplification factor simultaneously or alternately in the minimum adjustable unit.

  Next, a specific processing procedure by the digital camera 1 will be described in detail. Each process shown in the following flowchart is executed according to the procedure described in the program when the control unit 35 which is a microcomputer reads the predetermined program.

  FIGS. 8 and 9 are flowcharts showing the exposure operation by the digital camera 1, and shows the procedure of the exposure condition determination process with hysteresis according to the exposure diagram of FIG.

  When the “flicker removal mode” is set by a predetermined operation during recording or displaying of a moving image (Yes in step A11), the following processing is executed by the exposure control processing unit 35a provided in the control unit 35. Is done.

  The “flicker removal mode” can be arbitrarily set by the user. For example, when shooting is not performed under a fluorescent lamp, by setting a mode other than the “flicker removal mode”, FIGS. Unlike the diagram operation shown in FIG. 7, exposure control is performed in accordance with a diagram operation prioritizing other than flicker removal.

  First, as an initial setting process, a moving image frame rate of 30 frames per second is set (step A12). Further, the EV value is initialized to an arbitrary value, and the exposure conditions (various shooting parameters including the shutter speed) are initialized based on the EV value (steps A13 and A14).

  Subsequently, the brightness of the subject is measured from the amount of light incident on the CCD 25 through the lens optical system 22, and an EV value corresponding to the brightness of the subject is calculated (step A15). When the calculated EV value is higher than the previous EV value, that is, when it is necessary to adjust the exposure in the bright direction (Yes in step A16), the adjustment based on the shutter speed is performed within the specified range. . In this case, it is determined whether or not the shutter speed is faster than 1/64 seconds defined as the upper limit value of the shutter speed (step A17). As described above, 1/64 seconds is a speed value determined according to the power supply frequency of the fluorescent lamp, and if it is faster than 1/64 seconds, flicker may occur.

  If the shutter speed does not exceed 1/64 seconds (No in step A17), the exposure is adjusted by increasing the shutter speed as much as necessary based on the calculated EV value (step A18).

  If the shutter speed exceeds 1/64 seconds (Yes in step A17), the adjustment based on the amplification factor is performed within the specified range. At that time, it is determined whether or not the amplification factor is smaller than 0 dB (step A19). If the gain is not smaller than 0 dB (No in Step A19), the gain is reduced as much as necessary based on the calculated EV value with the shutter speed set to 1/64 seconds (Step A20). The exposure is adjusted at step A21.

  If the gain is smaller than 0 dB (Yes in Step A19), the calculation is performed with the shutter speed set to 1/48 seconds and the gain set to +3 dB (Steps AA22 and A23). Based on the EV value, another exposure condition (imaging parameter) is determined (step A31). The exposure condition determination process at this time will be described in detail later with reference to FIG.

  On the other hand, when the calculated EV value is lower than the previous EV value in the step A16, that is, when it is necessary to adjust the exposure in the dark direction, the adjustment by the shutter speed and the amplification factor is the same. Is performed within the prescribed range.

  That is, when it is necessary to adjust the exposure in the dark direction, it is first determined whether or not the exposure time is slower than 1/32 seconds defined as the lower limit value of the shutter speed (step A24). As described above, 1/32 seconds is a speed value necessary to secure a movie frame rate of 30 frames per second, and if it is slower than 1/32 seconds, smooth motion as a movie is guaranteed. It will not be done.

  If the shutter speed does not become slower than 1/32 seconds (No in step A24), exposure is adjusted by making the shutter speed as slow as necessary based on the calculated EV value (step A25).

  If the shutter speed is slower than 1/32 seconds (Yes in step A24), the adjustment based on the amplification factor is performed within the specified range. At that time, it is determined whether or not the amplification factor is larger than 6 dB (step A26). If the gain is not greater than 6 dB (No in Step A26), the gain is increased as much as necessary based on the calculated EV value with the shutter speed set to 1/32 seconds (Step A27). As a result, the exposure is adjusted (step A28).

  If the amplification factor exceeds 6 dB (Yes in step A26), the calculated EV is set with the shutter speed set to 1/48 seconds and the amplification factor set to +3 dB (steps A29 and A30). Based on the value, another exposure condition (imaging parameter) is determined (step A31). The exposure condition determination process at this time will be described in detail later with reference to FIG.

  The above operation is repeatedly performed during moving image shooting. Then, when the end of shooting is instructed by a predetermined operation (Yes in step A32), the process here ends.

  For the procedure of the exposure condition determination process with hysteresis according to the exposure diagram of FIG. 6, in the flowcharts shown in FIGS. 8 and 9, the step A22 is set to “set shutter speed to 1/32 seconds. Step A23 is changed to “Set gain to 0 dB”, Step A29 is changed to “Set shutter speed to 1/32 seconds”, and Step A30 is set to “Set gain to 0 dB”. Change it.

  Similarly, the exposure diagram of FIG. 4 can be realized by arranging the flowcharts of FIGS. 8 and 9.

  Next, the exposure condition determination process executed in step A31 will be described.

  FIG. 10 is a flowchart showing the processing operation, and shows the procedure of the exposure condition determination process when there is no hysteresis according to the exposure diagram of FIG. When exceeding the hysteresis range by adjusting the shutter speed and amplification factor, exposure conditions (various shooting parameters) are set as follows.

  That is, when the EV value set according to the brightness of the subject is larger than 10 (No in Step B11), the amplification factor is 0 to 6 dB, no pixel is added, the aperture is F4.0, and the ND filter is fixed to one stage. Then (step B12), the exposure is adjusted by adjusting the shooting parameters other than the fixed conditions (step B22). The shooting parameter in this case is the shutter speed. That is, when the subject is too bright, the exposure is adjusted by increasing the shutter speed to a specified range or more as shown in the exposure diagram of FIG.

  If the EV value is between 10 and 9 (No in Step B13), the gain is 0 to 6 dB, no pixel is added, and the aperture is fixed at F4.0 (Step B14). The exposure is adjusted by adjusting the parameters (step B22). Specifically, the exposure is adjusted by the ND filter.

  If the EV value is 9 or less (Yes in step B13), the EV value is fixed without an ND filter (step B15). At this time, if the EV value is larger than 8, that is, if the EV value is between 9 and 8 (No in step B16), the amplification factor is further fixed at 0 to 6 dB and no pixel addition (step B17). Exposure is adjusted by adjusting shooting parameters other than the fixed conditions (step B22). Specifically, the exposure is adjusted by the diaphragm.

  If the EV value is 8 or less (Yes in Step B16), in addition to fixing without the ND filter, the EV value is fixed to the aperture F2.8 (Step B18). At that time, if the EV value is larger than 6, that is, if the EV value is between 8 and 6 (No in Step B16), the amplification factor is further fixed to 0 to 6 dB (Step B20), and is fixed. Exposure is adjusted by adjusting shooting parameters other than the conditions (step B22). Specifically, exposure is adjusted by pixel addition.

  If the EV value is 6 or less (Yes in step B16), the pixel addition is fixed to 4 times (step B21) in addition to the absence of the ND filter and the stop F2.8 (step B21). The exposure is adjusted by adjusting the shooting parameters (step B22). The imaging parameter in this case is an amplification factor. In other words, when the subject is too dark, as shown in the exposure diagram of FIG. 6, the exposure is adjusted by raising the amplification factor to a specified range or more.

  As described above, when the shooting parameters other than the shutter speed or the amplification factor are appropriately used when setting the exposure conditions, the exposure can be adjusted while minimizing problems caused by the respective shooting parameters. .

  That is, for example, when the EV value is 8 to 6, by using the pixel addition magnification with relatively little image quality degradation, it is possible to minimize problems caused by using other shooting parameters.

  Further, if an ND filter having a large image quality change is used only when the subject is relatively bright, high image quality can be maintained over a wide exposure range, and even when the subject is very bright.

  Further, if the amplification factor is adjusted to a specified range or more only when the subject is relatively dark, it is possible to maintain high image quality over a wide exposure range, and to cope with a case where the subject is very dark.

  In the above-described embodiment, for example, the aperture (F value) is a binary value of F2.8 and F4.0, but the EV value may be adjusted more finely. The same applies to other shooting parameters, and the EV value may be adjusted more finely.

  Also, it may be possible for the user to arbitrarily select the hysteresis amount or flicker removal by mode setting, and the prescribed range of the shutter speed may be varied according to this selection. That is, for example, a first special mode that prioritizes the hysteresis amount and a second special mode that prioritizes flicker removal are prepared, and when the first special mode is set, the shutter speed regulation range is set. Is set to 1/32 to 1/128 seconds, and when the second special mode is set, the prescribed range of the shutter speed is set to 1/32 to 1/64 seconds. As a result, exposure control giving priority to either the hysteresis amount or flicker removal is performed while maintaining a moving image frame rate of 30 frames per second.

  In the above-described embodiment, the digital camera has been described as an example. However, the present invention is not limited to this. For example, in addition to a digital movie camera, a mobile phone or a PDA (Personal Digital Assistant) having a similar imaging function. It is also applicable to.

  In short, the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Moreover, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

FIG. 1 is a diagram showing an external configuration when a digital camera is taken as an example of an imaging apparatus according to an embodiment of the present invention. FIG. 1 (a) is mainly a front configuration, and FIG. It is a perspective view which shows the structure of a back surface. FIG. 2 is a block diagram showing an electronic circuit configuration of the digital camera in the embodiment. FIG. 3 is a diagram for explaining the relationship between the shutter speed and flicker of the digital camera in the embodiment. FIG. 4 is a diagram (exposure diagram) showing an exposure operation by the digital camera of the embodiment. FIG. 5 is a diagram partially showing a diagram operation in the vicinity of switching of the aperture (F value) in the exposure diagram. FIG. 6 is a diagram (exposure diagram) showing another exposure operation by the digital camera of the embodiment, and is a diagram showing an exposure operation when the gain is preferentially adjusted in addition to the shutter speed. FIG. 7 is a diagram (exposure diagram) showing another exposure operation by the digital camera of the embodiment, and is a diagram showing the exposure operation when adjusting the shutter speed and the amplification factor simultaneously. FIG. 8 is a flowchart (part 1) showing the procedure of the exposure condition determination process when there is hysteresis by the digital camera of the embodiment. FIG. 9 is a flowchart (No. 2) showing the procedure of the exposure condition determination process when hysteresis is provided by the digital camera of the embodiment. FIG. 10 is a flowchart showing the procedure of the exposure condition determination process when there is no hysteresis by the digital camera of the embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Digital camera, 2 ... Body, 3 ... Shooting lens, 4 ... Self-timer lamp, 5 ... Optical finder window, 6 ... Strobe light emission part, 7 ... Microphone part, 8 ... Power key, 9 ... Shutter key, 10 ... Photographing Mode key, 11 ... Playback mode key, 12 ... Optical viewfinder, 13 ... Speaker unit, 14 ... Macro key, 15 ... Strobe key, 16 ... Menu (MENU) key, 17 ... Ring key, 18 ... Set key, DESCRIPTION OF SYMBOLS 19 ... Display part, 20a, 20b ... Zoom key, 21 ... Motor, 22 ... Lens optical system, 23 ... Filter mechanism, 24 ... Diaphragm mechanism, 25 ... CCD, 25a ... Pixel addition processing part, 26 ... Timing generator (TG) 27 ... Driver, 28 ... Amplifier, 29 ... Sample hold circuit (S / H), 30 ... A / D converter, 31 ... Image processing circuit, 32 ... DM Controller 33 ... DRAM interface (I / F) 34 ... DRAM 35 ... Control unit 35a ... Exposure control processing unit 36 ... Key input unit 37 ... VRAM controller 38 ... VRAM 39 ... Digital video encoder 40 ... JPEG circuit, 41 ... Memory, 42 ... Audio processing unit, 43 ... USB interface (I / F), 44 ... Strobe drive unit.

Claims (12)

An image pickup apparatus capable of recording or displaying image data continuously obtained from an image pickup device as a moving image,
A measuring means for measuring the brightness of the subject;
A determining unit that determines a plurality of shooting parameters including a shutter speed based on the brightness of the subject measured by the measuring unit;
First defining means for setting a lower limit value of the shutter speed to a first speed value determined corresponding to a frame rate necessary for a moving image;
A second defining means for determining an upper limit value of the shutter speed as a second speed value determined in correspondence with a frequency of an external light source having a blinking characteristic;
During the recording or display of a moving image, the shutter speed is preferentially adjusted when adjusting the values of various shooting parameters determined by the determining unit according to the brightness of the subject that is sequentially measured by the measuring unit. An image pickup apparatus comprising: an exposure control unit that adjusts another shooting parameter to perform exposure control when the shutter speed exceeds a range defined by the first and second defining units. Amplification factor control means for controlling the amplification factor of the signal output from the image sensor,
The various photographing parameters include an amplification factor by the amplification factor control means,
The exposure control means prioritizes the amplification factor in addition to the shutter speed when adjusting the values of various shooting parameters determined by the determination means according to the brightness of the subject sequentially measured by the measurement means. The image pickup apparatus according to claim 1, wherein the image pickup apparatus is adjusted in an automatic manner.   The imaging apparatus according to claim 2, wherein the exposure control unit adjusts the maximum value of the amplification factor by limiting to a predetermined value.   The exposure control means adjusts the shutter speed when the exposure value is made to follow in the direction of darkening, and adjusts the amplification factor when making the exposure value follow in the direction of making the exposure value brighter. Imaging device.   The imaging apparatus according to claim 2, wherein the exposure control unit adjusts each of the shutter speed and the amplification factor simultaneously or alternately in a minimum unit that can be adjusted. Pixel addition processing means for adding data of each pixel of the image sensor at a predetermined magnification;
The various shooting parameters include a pixel addition magnification by the pixel addition processing means,
The imaging apparatus according to claim 1, wherein the exposure control unit adjusts the pixel addition magnification when the shutter speed exceeds a range defined by the first and second defining units. Pixel addition processing means for adding data of each pixel of the image sensor at a predetermined magnification;
Optical filter means for limiting the amount of light incident on the image sensor stepwise,
The various shooting parameters include a pixel addition magnification by the pixel addition processing unit and a filter stage number by the optical filter unit,
The exposure control means includes
Determining means for determining the brightness of the subject when the shutter speed exceeds a range defined by the first and second defining means;
If the brightness of the subject is within a predetermined brightness range, the pixel addition magnification is adjusted by the determination means. If the brightness of the subject is brighter than the predetermined brightness, the number of filter stages is adjusted. The imaging apparatus according to claim 1, further comprising: a parameter changing unit. Pixel addition processing means for adding data of each pixel of the image sensor at a predetermined magnification;
An amplification factor control means for controlling the amplification factor of the signal output from the image sensor;
The various shooting parameters include a pixel addition magnification by the pixel addition processing unit and an amplification factor by the amplification factor control unit,
The exposure control means includes
Determining means for determining the brightness of the subject when the shutter speed exceeds a range defined by the first and second defining means;
When the brightness of the subject is within the predetermined brightness range, the pixel addition magnification is adjusted by the determination means, and when the brightness of the subject is darker than the predetermined brightness, the amplification factor is adjusted. The imaging apparatus according to claim 1, further comprising: a parameter changing unit. It has mode setting means to set the special mode,
The exposure control means preferentially adjusts the shutter speed within the specified range when the special mode is set by the mode setting means, and sets other shooting parameters when the shutter speed exceeds the specified range. The imaging apparatus according to claim 1, wherein exposure control is performed by adjusting. Comprising mode setting means for selectively setting the first special mode and the second special mode;
When the first special mode is set by the mode setting means, the first and second specifying means set a specified range giving priority to a hysteresis amount, and the second special mode is set. Set a specified range that prioritizes flicker removal,
The exposure control unit preferentially adjusts the shutter speed within a specified range set according to the first or second special mode, and adjusts other shooting parameters when the shutter speed exceeds the specified range. The image pickup apparatus according to claim 1, wherein exposure control is performed. An exposure control method used in an imaging apparatus capable of recording or displaying image data continuously obtained from an imaging element as a moving image,
Measuring the brightness of the subject;
A step of determining a plurality of shooting parameters including a shutter speed based on the measured brightness of the subject;
Setting a lower limit value of the shutter speed to a first speed value determined in accordance with a frame rate necessary for a moving image;
Determining an upper limit value of the shutter speed as a second speed value determined in correspondence with a frequency of an external light source having a blinking characteristic;
During the recording or display of a moving image, when adjusting the values of the various shooting parameters according to the brightness of the subject that is sequentially measured, the shutter speed is preferentially adjusted, and the shutter speed is the first and first shutter speeds. And adjusting exposure control by adjusting other imaging parameters when the range defined by the speed value of 2 is exceeded. A program executed by a computer mounted on an imaging apparatus capable of recording or displaying image data continuously obtained from an imaging element as a moving image,
In the computer,
A function to measure the brightness of the subject,
A function for determining a plurality of shooting parameters including the shutter speed based on the measured brightness of the subject,
A function for setting a lower limit value of the shutter speed to a first speed value determined in accordance with a frame rate necessary for a moving image;
A function of determining an upper limit value of the shutter speed as a second speed value determined corresponding to a frequency of an external light source having a blinking characteristic;
During the recording or display of a moving image, when adjusting the values of the various shooting parameters according to the brightness of the subject that is sequentially measured, the shutter speed is preferentially adjusted, and the shutter speed is the first and first shutter speeds. And a function for performing exposure control by adjusting other shooting parameters when the range defined by the speed value of 2 is exceeded.

Images