JP4343340B2 - Image processing apparatus and control method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention provides an image processing apparatus for capturing, recording or reproducing still images and moving images.PlaceAndThatIt relates to a control method.
[0002]
[Prior art]
Conventionally, an image processing apparatus such as an electronic camera that records and reproduces still images and moving images using a memory card having a solid-state memory element as a recording medium is already on the market. Electronic cameras equipped with an electronic viewfinder such as a color liquid crystal panel are also on the market. According to these electronic cameras, by continuously displaying images obtained from the image sensor before photographing, it is possible for the user of the electronic camera to determine the composition or to reproduce and check the photographed images. is there.
[0003]
[Problems to be solved by the invention]
In such an image processing apparatus using an image sensor such as a conventional electronic camera, an object scene image incident from a lens via a diaphragm / shutter is formed on the image sensor. In general, image data obtained from an image sensor is divided into a plurality of pieces, and TTL (through-the-lens) exposure control is performed in accordance with light flux integration data obtained from each divided area.
[0004]
In this type of metering method, there is a limit to the luminance range that can be measured at once with the dynamic range of the imaging mechanism including the image sensor. Had to be done. That is, photometry is performed in a state in which the aperture and the shutter are controlled to a standard set value corresponding to the photographing mode, and the aperture or the shutter is controlled according to the difference from the data indicating the proper exposure of the luminous flux integral data. Then, it has been necessary to perform so-called feedback control in which the proper exposure is determined by performing photometry to converge.
[0005]
Such control varies in the time until a proper exposure is obtained depending on how much the standard setting value according to the shooting mode differs from the actual brightness and how much the dynamic range is. It means to end up.
[0006]
In addition, when using the electronic viewfinder, it is necessary for the user to adjust the angle of view, so the automatic exposure control mechanism is activated and the image displayed on the electronic viewfinder is in an approximately appropriate exposure state. It is common. In this case, since the luminance range of the object scene can be grasped before the shooting trigger occurs, the convergence time of the feedback control is shortened.
[0007]
However, on the other hand, power consumption increases. Therefore, when the power that can be supplied is reduced and shooting with the optical viewfinder without using the electronic viewfinder, a release time lag occurs when the shooting trigger is given in the same way as when using the electronic viewfinder, and the shutter timing There is a risk of missing.
[0008]
  In view of such circumstances, the present invention is excellent in use and handling.,Proper exposure controlImage processing apparatus capable of performingandThatAn object is to provide a control method.
[0009]
[Means for Solving the Problems]
  Of the present inventionThe image processing devicePhotoelectric conversion means for converting an optical image into an electrical signal;Display means for displaying an image based on the electrical signal converted by the photoelectric conversion means;A photometric means for obtaining a field luminance based on the electric signal converted by the photoelectric conversion means; an exposure control means for performing exposure control based on a photometric result of the photometric means;First photometry for obtaining a plurality of field luminances based on the electrical signal obtained by performing exposure a plurality of times under different exposure conditions in a plurality of vertical synchronization periods, and exposure once in the plurality of vertical synchronization periods Control means for controlling the photometry means to perform any one of the second photometry for obtaining the field luminance based on the electric signal obtained by performing the display, and the control means comprises the display Controlling the photometry means to perform the first photometry when the images are not sequentially displayed on the means, and repeatedly performing the second photometry while the images are sequentially displayed on the display means. The exposure control means selects and selects one field luminance from the plurality of field luminances determined by the first metering when the light metering means performs the first metering. Exposure control based on the controlled field brightness. The features.
[0010]
  In addition, the present inventionThe control method includes a photoelectric conversion unit that converts an optical image into an electric signal, a display unit that displays an image based on the electric signal converted by the photoelectric conversion unit, and a target that is based on the electric signal converted by the photoelectric conversion unit. A photometry means for obtaining a field brightness, the exposure control step for performing exposure control based on a photometry result of the photometry means, and a plurality of times under different exposure conditions in a plurality of vertical synchronization periods. First photometry for determining a plurality of field luminances based on the electrical signal obtained by performing the exposure, and the electrical signal obtained based on the electrical signal obtained by performing the exposure once in the plurality of vertical synchronization periods. And a control step for controlling the photometry means so as to perform either one of the second photometry for obtaining the field luminance, and the control step does not sequentially display the image on the display means. Performing the first photometry, and controlling the photometry means so as to repeatedly perform the second photometry while the images are sequentially displayed on the display means, and the exposure control step includes the photometry means When performing the first photometry, one field luminance is selected from the plurality of field luminances determined by the first photometry, and exposure control is performed based on the selected field luminance. It is characterized by performing.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a configuration of an embodiment of the present invention. In FIG. 1, reference numeral 100 denotes an image processing apparatus. 10 is a variable power lens group, 11 is a focusing lens group, 12 is a shutter having a diaphragm function, 14 is an image sensor that converts an optical image into an electric signal, and 15 is image sensitivity adjustment that sets the sensitivity of the image sensor 14. In this embodiment, a gain amplifier that can be linearly adjusted from 0 to 24 dB is employed.
[0030]
16 is an A / D converter that converts the analog signal output of the image sensor 14 into a digital signal, and 18 is a timing at which a clock signal and a control signal are supplied to the image sensor 14, the A / D converter 16, and the D / A converter 26. The generation circuit is controlled by the memory control circuit 22 and the system control circuit 50. The variable power by the variable power lens group 10 is divided into 8 parts from the wide end to the tele end, and a configuration that enables zooming in 9 positions including the wide end and tele end is adopted. .
[0031]
An image processing circuit 20 performs predetermined pixel interpolation processing and color conversion processing on the data from the A / D converter 16 or the data from the memory control circuit 22. The image processing circuit 20 performs predetermined calculation processing using the captured image data, and the system control circuit 50 controls the automatic exposure control means 40 and the distance measurement control means 42 based on the obtained calculation results. TTL AF (autofocus) processing, AE (automatic exposure) processing, and EF (flash pre-emission) processing are performed. Further, the image processing circuit 20 performs predetermined arithmetic processing using the captured image data, and also performs TTL AWB (auto white balance) processing based on the obtained arithmetic result.
[0032]
A memory control circuit 22 controls the A / D converter 16, the timing generation circuit 18, the image processing circuit 20, the image display memory 24, the D / A converter 26, the memory 30, and the compression / decompression circuit 32. The data of the A / D converter 16 is written into the image display memory 24 or the memory 30 via the image processing circuit 20 and the memory control circuit 22, or the data of the A / D converter 16 is directly written via the memory control circuit 22. It is.
[0033]
Reference numeral 24 denotes an image display memory, 26 denotes a D / A converter, and 28 denotes an image display unit including a TFT LCD or the like. The display image data written in the image display memory 24 is displayed by the image display unit 28 via the D / A converter 26. If the image data captured using the image display unit 28 is sequentially displayed, an electronic viewfinder function can be realized. The image display unit 28 can arbitrarily turn on / off the display according to an instruction from the system control circuit 50. When the display is turned off, the power consumption of the image processing apparatus 100 can be greatly reduced.
[0034]
Reference numeral 30 denotes a memory for storing captured still images and moving images, and has a sufficient storage capacity for storing a predetermined number of still images and moving images for a predetermined time. Thereby, even in the case of continuous shooting or panoramic shooting in which a plurality of still images are continuously shot, a large amount of images can be written in the memory 30 at high speed. The memory 30 can also be used as a work area for the system control circuit 50.
[0035]
A compression / decompression circuit 32 compresses and decompresses image data by adaptive discrete cosine transform (ADCT) or the like. The compression / decompression circuit 32 reads an image stored in the memory 30, performs a compression process or an expansion process, and writes the processed data to the memory 30.
[0036]
Reference numeral 40 denotes a shutter 12 having an aperture function, an electronic shutter control unit that controls the accumulation time from the charge discharging operation to the reading operation of the image sensor 14 by the timing generation circuit 18, and an automatic exposure control that controls the imaging sensitivity adjustment unit 15. This means also has a flash light control function in cooperation with the flash 48. Reference numeral 42 denotes a distance measurement control means for controlling the focusing of the focusing lens 11, reference numeral 44 denotes a zoom control means for controlling the zooming of the variable magnification system lens 10, and reference numeral 46 denotes a barrier control means for controlling the operation of the protection means 102 serving as a barrier. is there. A flash 48 has an AF auxiliary light projecting function and a flash light control function. The exposure control means 40 and the distance measurement control means 42 are controlled using the TTL method, and the system control circuit 50 uses the exposure control means 40 and the distance measurement based on the calculation result obtained by calculating the captured image data by the image processing circuit 20. Control is performed on the control means 42. Details of the automatic exposure control will be described later.
[0037]
50 is a system control circuit that controls the entire image processing apparatus 100, 52 is a memory that stores constants, variables, programs, and the like for operation of the system control circuit 50, and 54 is a system control circuit 50 according to program execution. The display unit includes a liquid crystal display device, a speaker, and the like that display an operation state, a message, and the like using characters, images, sounds, and the like. The display unit 54 is installed at a single or a plurality of positions near the operation unit of the image processing apparatus 100 so as to be easily visible, and is configured by, for example, a combination of an LCD, an LED sound emitting element, and the like. The display unit 54 is also partially installed in the optical viewfinder 104.
[0038]
Among the display contents of the display unit 54, what is displayed on the LCD or the like includes single shot / continuous shooting display, long second shooting display, night view shooting display, self-timer display, compression rate display, recording pixel number display, number of recordings Display, remaining shot number display, shutter speed display, aperture value display, exposure compensation display, flash display, red-eye reduction display, red-eye reduction lamp lighting, elapsed time display from previous shooting, macro shooting display, buzzer setting display , Clock battery level display, battery level display, error display, multi-digit information display, recording medium 200 and 210 attachment / detachment status display, communication I / F operation display, date / time display, and the like. Among the display contents of the display unit 54, what is displayed in the optical viewfinder 104 includes in-focus display, camera shake warning display, flash charge display, shutter speed display, aperture value display, exposure correction display, and the like.
[0039]
Reference numeral 56 denotes an electrically erasable and recordable nonvolatile memory. For example, an EEPRPM is used for the nonvolatile memory 56.
[0040]
Reference numerals 60, 62, 64, 66, 68, and 70 are operation means for inputting various operation instructions of the system control circuit 50. A single unit such as a switch, a dial, a touch panel, pointing by line-of-sight detection, a voice recognition device, or the like Consists of multiple combinations. Here, a specific description of these operating means will be given. Reference numeral 60 denotes a mode dial switch, which can switch and set various function modes such as power-off, automatic shooting mode, shooting mode, panoramic shooting mode, playback mode, multi-screen playback / erase mode, and PC connection mode.
[0041]
Reference numeral 62 denotes a shutter switch SW1, which is turned on during the operation of a shutter button (not shown) and instructs to start operations such as AF processing, AE processing, AWB processing, and EF processing.
Reference numeral 64 denotes a shutter switch SW2, which is turned on upon completion of an operation of a shutter button (not shown), and writes the image data read from the image sensor 12 to the memory 30 via the A / D converter 16 and the memory control circuit 22. Exposure processing, development processing using computations in the image processing circuit 20 and the memory control circuit 22, reading out image data from the memory 30, compression in the compression / decompression circuit 32, and recording in which the image data is written to the recording medium 200 or 210 Instructs the start of a series of processing such as processing.
[0042]
Reference numeral 66 denotes an image display ON / OFF switch, which can set ON / OFF of the image display unit 28. With this function, it is possible to save power by cutting off the current supply to the image display unit such as a TFT LCD when photographing using the optical viewfinder 104.
[0043]
Reference numeral 70 denotes an operation unit including various buttons, a touch panel, etc., a menu button, a set button, a macro / non-macro switching button, a multi-screen playback page break button, a flash setting button, a single shooting / continuous shooting / self-timer / long seconds. (Slow Shutter) / Night Scene Shooting Mode Switch Button, Menu Move + (Plus) Button, Menu Move-(Minus) Button, Playback Image Move + (Plus) Button, Playback Image-(Minus) Button, Shooting Image Quality Selection Button, Exposure A correction button, a date / time setting button, and the like are included.
[0044]
Reference numeral 80 denotes power supply control means, which includes a battery detection circuit, a DC-DC converter, and a switch circuit for switching a block to be energized. Then, the presence / absence of a battery, the type of battery, and the remaining battery level are detected, the DC-DC converter is controlled based on the detection result and an instruction from the system control circuit 50, and a recording medium is supplied with a necessary voltage for a necessary period. Supply to each part including. Reference numerals 82 and 84 denote connectors, and 86 denotes a power supply means including a primary battery such as an alkaline battery or a lithium battery, a secondary battery such as a NiCd battery, NiMH battery, or Li battery, or an AC adapter.
[0045]
90 and 94 are interfaces with a recording medium such as a memory card and a hard disk, 92 and 96 are connectors for connecting to a recording medium such as a memory card and a hard disk, and 98 is a recording medium 200 or 210 attached to the connector 92 or 96. It is a recording medium attachment / detachment detecting means for detecting whether or not there is. In this embodiment, there are two interfaces and connectors for attaching the recording medium. Of course, the interface and the connector for attaching the recording medium may have a single or a plurality of systems. Moreover, it is good also as a structure provided with combining the interface and connector of a different standard. The interface and the connector may be configured using a PCMCIA card, a CF (compact flash) card, or the like based on a standard.
[0046]
Further, when the interfaces 90 and 94 and the connectors 92 and 96 are configured in accordance with a standard such as a PCMCIA card or a CF card, a LAN card, modem card, USB card, IEEE 1394 card, P1284 card, SCSI card, PHS By connecting various communication cards such as a communication card, image data and management information attached to the image data can be transferred to and from other computers and peripheral devices such as a printer.
[0047]
A protection unit 102 is a barrier that prevents the image pickup unit from being soiled or damaged, and covers the image pickup unit including the variable power lens 10 and the focusing lens 11 of the image processing apparatus 100. It is a protective means that is a barrier to prevent damage and breakage.
Reference numeral 104 denotes an optical viewfinder, which can take an image using only the optical viewfinder without using the electronic viewfinder function of the image display unit 28. Also, some functions of the display unit 54 such as a focus display, a camera shake warning display, a flash charge display, a shutter speed display, an aperture value display, an exposure correction display, and a macro shooting setting display are installed in the optical viewfinder 104. ing.
[0048]
A communication unit 110 has various communication functions such as RS232C, USB, IEEE1394, P1284, SCSI, modem, LAN, and wireless communication.
Reference numeral 112 denotes a connector for connecting the image processing apparatus 100 to another device by the communication unit 110 or an antenna in the case of wireless communication.
[0049]
Reference numeral 200 denotes a recording medium such as a memory card or a hard disk. The recording medium 200 includes a recording unit 202 composed of a semiconductor memory, a magnetic disk, and the like, an interface 204 with the image processing apparatus 100, and a connector 206 for connecting with the image processing apparatus 100.
Reference numeral 210 denotes a recording medium such as a memory card or a hard disk. The recording medium 210 includes a recording unit 212 composed of a semiconductor memory, a magnetic disk, or the like, an interface 214 with the image processing apparatus 100, and a connector 216 for connecting with the image processing apparatus 100.
[0050]
  Here, FIGS. 5 to 9 show flowcharts of the automatic exposure control means in the present embodiment. The automatic exposure control means of this embodiment is written in the program area 52 of the system control circuit 50 and controls the exposure control means 40 based on the calculation result by the CPU.do itDo. In addition, this automatic exposure control uniquely defines the exposure control speed and the exposure control accuracy in accordance with the shooting operation preparation period, immediately before the main exposure operation, the image display preparation period on the image display unit 28, and the image display on the image display unit 28. The control is determined according to the situation. This automatic exposure control stores the internal state and determines its own exposure control method according to the transition of the state.
[0051]
The system control circuit 50 designates a mode for specifying an operation period when the automatic exposure control means is activated. According to the mode for specifying the operation period, the photometric method and the aperture 12 are controlled, and the electronic shutter control and the imaging sensitivity adjusting means 15 for controlling the accumulation time from the charge discharging operation to the reading operation of the image sensor 14 by the timing generation circuit 18. Control is performed while changing the program diagram configured so that the control value is uniquely obtained from the subject brightness.
[0052]
The basic structure of this automatic exposure control means is shown in FIG. The sub-system of the automatic exposure control means includes the control means for the diaphragm 12, the electronic shutter control means for controlling the accumulation time from the charge discharging operation to the reading operation of the image sensor 14 by the timing generation circuit 18, and the imaging sensitivity adjusting means 15. There are control means. In addition to this, there are photometry means, a program diagram, and exposure control value calculation means for analyzing the program diagram and calculating an exposure control value. In the case of TTL photometry using the image sensor 14, since the dynamic range of the image sensor 14 is narrow, it is impossible to perform photometry at once for all the luminances within the interlocking range of the automatic exposure control. Usually, the range in which photometry can be performed at a time is about four steps.
[0053]
FIG. 11 shows a timing chart of automatic exposure control showing a relative photometry method.
The automatic exposure control means is an exposure control value that is uniquely determined from a field luminance (Bv) value and a program diagram, that is, an aperture control (Av) value, an electronic shutter control (Tv) value, and an imaging sensitivity adjustment (DG). A value is obtained, and each control value is transferred to each control means of the subsystem. The aperture control means, electronic shutter control means, and imaging sensitivity adjustment means of the subsystem convert the delivered Av value, Tv value, and DG value into actual control data depending on the devices that are controlled by each, and the exposure control means 40 Control is performed. Details of each device-dependent control data and control method are omitted. However, it is assumed that the setting of the clear pulse meaning the charge discharging operation of the image sensor becomes effective on the boundary of the readout pulse meaning the charge readout operation that appears next after the setting is completed.
[0054]
The automatic exposure control means waits for the completion of exposure of the image sensor from the first control in FIG. The image processing circuit 20 sequentially reads the charge signal read from the image sensor 14 via the A / D converter 16 and performs light beam integration for each region obtained by dividing the integration region set in advance by the system control circuit 50. Within the next vertical synchronization period in which the image sensor 14 is exposed, the photometry means reads the integrated light beam integration result from the image processing circuit 20 together with the end of the region. The photometry means calculates the evaluation value for each area according to the area ratio of the divided area after converting the integration result for each divided area into an integrated value for each pixel for each area. To do.
[0055]
  The image processing circuit 20 counts the frequency indicating the degree of detection of each level for each level of the luminance component in the input image data in addition to the integration circuit.To do(Hereinafter, luminance distribution extracting means) is possible. In addition, the photometric means has a threshold value of high luminance and low luminance for each pixel in each area, and the threshold value is calculated when calculating the evaluation value for each area.BeyondThe data of pixels below or below is discarded and calculated. The photometric means further performs predetermined weighting on the evaluation value for each area. Then, a luminance (ΔBv) value corresponding to a deviation amount from the appropriate exposure level is calculated in accordance with a photometric mode such as evaluation photometry, center-weighted photometry, or spot photometry. Of course, it may be configured in the image processing circuit 20 to eliminate excess data when integrating or generating a luminance distribution.
[0056]
The automatic exposure control means adds the ΔBv value obtained as a result of the calculation to the Bv value used for the previous control, calculates the next target Bv value, and determines the next target uniquely determined from the program diagram. An exposure control value is calculated. Each calculated control value is input to each control means, and photometry and control are repeated until the ΔBv value falls within a predetermined range. Therefore, exposure control is performed once using two vertical synchronization periods.
[0057]
  In the timing chart shown in FIG. 11, the next target exposure control value determined by the first calculation result.Exposure control operation based onHowever, the control is completed within a range that does not extend to the exposure time of the next image sensor, that is, before the clear pulse of the image sensor stops. Note that this is not necessarily guaranteed depending on the field luminance. Therefore, the next target exposure control value determined by the first calculation resultExposure control operation based onHowever, when the exposure time is long enough to extend over the clear pulse of the image sensor, the next vertical transfer pulse, that is, the readout pulse of the image sensor is output without using the exposure result of the next image sensor. The data integrated up to can no longer be used. Although it has been described above that exposure control is performed once in two vertical synchronization periods, actually, exposure control is performed once in two to three vertical synchronization periods. Of course, the same can be said when the histogram is generated by the luminance distribution extraction means.
[0058]
In a state in which the captured image is displayed on the image display unit 28, the luminance of the field may change greatly in order for the user to determine the angle of view. In this state, if exposure control is performed in direct response to the field luminance, the image is displayed on the image display unit 28, but the luminance change of the image becomes severe, and the image may become unsightly. Therefore, the range of ΔBv value (appropriate exposure range), which is a judgment to repeat photometry and control, is wide. Once ΔBv value falls within the appropriate exposure range, control until ΔBv value exceeds the exposure monitoring range wider than the appropriate exposure range. Only metering is performed. Further, by dividing and compressing the ΔBv value to be added when calculating the target Bv value according to the magnitude of the measured ΔBv value with control, the time until proper exposure is obtained is delayed. As described above, since automatic exposure control during image display has a time margin, there is no problem even in relative photometry.
[0059]
As described above, in the TTL metering method using the image sensor, the width of the dynamic range of the image sensor is approximately four steps, and thus the entire interlocking range cannot be measured at a time. Therefore, when the photometric operation is started, it is preferable to perform control using a standard virtual field brightness (Start Bv) value and relatively search for the field brightness value. However, the larger the difference between the Start Bv value at the start of photometry and the actual Bv value, the longer it takes to obtain proper exposure. In other words, the relative photometry method that is performed once the proper exposure is obtained can be used for automatic exposure control during image display, but it can be used for shooting preparation periods and when generating images to be displayed on the image display section. This is not suitable for photometry when there is not enough room.
[0060]
The timing chart shown in FIG. 10 shows automatic exposure control when using a scanning photometry method that is performed when there is not enough time such as a shooting preparation period or when generating an image to be displayed on the image display unit. It is.
When the dynamic range of the image sensor of this embodiment is based on the integral value per pixel at the time of proper exposure, it is assumed that one-step photometry is possible on the high luminance side and three steps on the low luminance side. Further, when the interlocking range of the automatic exposure control is expressed by an Ev value in terms of ISO 100 (Ev = Bv + Sv, Sv = 5), it is assumed that Ev7 to Ev17. Further, the automatic exposure control means has a first control value Ev 16, a second control value Ev 13, and a third control value Ev 10 as data.
[0061]
  The range in which photometry can be performed with the first control value is Ev13 to Ev17,With control valueThe meterable range is Ev10 to Ev14, and the meterable range with the third control value is Ev7 to Ev11. Further, these control values vary in detail depending on the specifications of the image sensor 14 and the diaphragm. In the flow chart of the photometry method shown in FIG. 8, the Av value and the DG value are fixed values in common for all control values, and are operations in the case of controlling only by the Tv value.
[0062]
Next, the operation will be described with reference to the timing chart of FIG.
First, as in the case of the relative photometry method, the automatic exposure control means inputs the first control value to each control means, converts it to an actual control value depending on each device, and then to the exposure control means 40. Apply control. As shown in FIG. 12, the control timing is such that the clear pulse setting is performed near the falling edge of the vertical synchronization signal, and the aperture setting is performed near the readout pulse. The imaging sensitivity not shown is set at the same timing as the clear pulse setting.
[0063]
  In the vertical synchronization period in which the first control is performed, only the image sensor is exposed, and the light beam integration is performed and the result is not used, or the integration may not be performed. Second electronic shutter control at the falling edge of the second vertical synchronization signal generated during the first exposureTheAperture control is performed at the timing of the readout pulse. In the second vertical synchronization period in which the second control is performed, the light beam integration of the image exposed in the first vertical synchronization period is performed together with the exposure of the second image sensor, and the first integration is performed when the integration region ends. The result is read to determine the first ΔBv value. Also, the first vertical synchronization periodWhenSimilarly of the image sensorSecondThe third electronic shutter control is performed at the falling timing of the third vertical synchronizing signal generated during the exposure, and the aperture control is performed at the timing of the readout pulse. Further, the third vertical synchronization period is controlled in the same manner as the second vertical synchronization period. In the fourth vertical synchronization period after the third exposure, the third light flux integration and the third ΔBv value are calculated, and selected from the ΔBv values calculated in the past three vertical synchronization periods. Do it. Control is performed by obtaining a target ΔBv value from the selected ΔBv and the exposure control value when the ΔBv value is measured, and calculating a target control value uniquely determined from the program diagram.
[0064]
The method for selecting the ΔBv value is not particularly limited. For example, when the photometric Bv value exists from Ev 13 to Ev 14, if importance is attached to the linearity of the integration result, the target Bv value determined from the first ΔBv value and the first control value is set. Adopt. Alternatively, if importance is attached to avoiding diffraction due to the aperture diameter of the stop, a target Bv value determined from the second ΔBv value and the second control value is adopted.
[0065]
Thus, by performing photometry so that the dynamic range of the image sensor overlaps by one stage and covers the entire interlocking range, the field luminance can be measured within three vertical synchronization periods. Therefore, it is effective in a state where priority is given to speed, such as automatic exposure control performed before displaying an image on the image display unit 28 and exposure control performed immediately before shooting.
[0066]
In the above description, photometry is performed from the high luminance side, but the order combination is not related to the essence of the present invention. Further, the first, second, and third control values may be configured so that only the electronic shutter changes. Alternatively, all may be performed by controlling only the aperture or the imaging sensitivity adjustment value. This combination is a matter determined by whether the aperture is established within the time from the timing of the readout pulse until the clear pulse stops or whether the imaging sensitivity is switched. Further, in the present embodiment, the amount of overlap is one stage, but there is no limitation to this.
[0067]
Furthermore, in the present embodiment, all control, integration, and photometry calculations determined in advance are performed. For example, when it is possible to determine that the exposure is appropriate when the first photometry result is obtained, the subsequent steps are performed. Application such as prohibiting the control, integration and photometry calculation, changing the order of control, or omitting specific control is possible. Further, the photometry part in the scan photometry method is not performed by the integration means of the image processing circuit 20 but by the histogram by the luminance distribution extraction means, and the control and exposure are stopped when the deviation of the luminance distribution in the histogram enters a predetermined range. You can also
[0068]
Next, the automatic exposure control operation will be described with reference to FIG.
First, when the automatic exposure control means is activated, the activated automatic exposure control means recognizes the current mode (step S501). When the mode change is recognized (step S502), the proper exposure flag is canceled and the field luminance in the immediately previous mode is stored (step S503).
Next, a program diagram is selected (step S504) and registered in the exposure control value calculation means (step S505).
Next, photometry area setting required for photometry is performed (step S506).
[0069]
When the mode is not changed, such as when the image display period mode (Mode = 2) is activated, the subsequent exposure control is performed (to step S510).
[0070]
When the mode is changed and the mode is the image display period mode (Mode = 2) or the mode immediately before the main exposure operation (Mode = 4) (Step S507), the field brightness value stored in Step S503 is set to the Bv value. The Sv value is added and input to the exposure control value calculation means, and the initial Av value, Tv value, and DG value are obtained (step S508).
Next, control is performed by an aperture control unit, an electronic shutter unit, and an imaging sensitivity adjustment unit, respectively (step S509). In the exposure control (step S509), as described above, after conversion into device-dependent control data, the aperture 12, electronic shutter, and imaging sensitivity are controlled. Although not shown, each control unit stores the control value set last or the control data controlled last. When they are the same control value or control data, actual control is not performed. Also, the timing generation means such as interrupt processing is not particularly defined with the set timing.
[0071]
  Subsequently, the photometric means is activated to perform photometry, and the Bv value and ΔBv value are obtained (step S510). If the mode is the image display period mode (Mode = 2) or the mode immediately before the main exposure operation (Mode = 4) (step S511), the appropriate exposure flag state is checked (step S515). If it is ON,MeteredIt is checked whether the ΔBv value is within the exposure monitoring range (step S516). If it is within range, return without doing anything. Further, when it is not within the exposure monitoring range (step S516) and when the appropriate exposure flag is OFF (step S517), the Sv value is added to the photometric target Bv value and input to the exposure control value calculation means. Then, the target Av value, the Tv value, and the DC value are obtained (step S517), and the control process is performed based on each control value (step S518).
[0072]
Next, it is checked whether or not the photometric ΔBv value is within the appropriate exposure range for control (step S519). Only when it is within the range, the appropriate exposure flag is set (step S520), and the process returns.
[0073]
Next, photometric control (S510) performed within exposure control will be described with reference to FIG.
First, it is determined whether it is an image display preparation period (Mode = 1) (step S531).
If it is the image display preparation period, scan photometry is performed (step S532), and the process returns.
[0074]
If it is not the image display preparation period mode, it is determined whether the image display period mode (Mode = 2) is set (step S533).
If it is in the image display period mode, relative photometry is performed (step S534) and the process returns.
[0075]
  If it is not the image display period mode, it is determined whether or not the shooting preparation operation period mode (Mode = 3) is set (step S535). If it is in the shooting preparation operation period mode, the image display flag is determined (step S536). When the image display flag is set to ON, when the mode is changed(Step S503)The field luminance in the immediately previous mode stored in (5) is returned (step S537). If the image display flag is not set, scan photometry is performed (step S538) and the process returns.
[0076]
If it is determined that neither mode is applicable (step S535), the mode is set to the mode immediately before the main exposure operation (Mode = 4), and the relative photometry is performed (step S539).
[0077]
Here, FIG. 8 shows a case where the scanning photometry operation is controlled only by the electronic shutter. FIG. 9 shows the operation of relative photometry. These operations are as described in the previous timing chart (FIG. 10).
[0078]
Next, the operation of the image processing apparatus 100 will be described with reference to FIGS. 2 and 3.
Upon power-on such as battery replacement, the system control circuit 50 initializes flags, control variables, and the like (step S101), and initializes the image display of the image display unit 28 to an OFF state (step S102).
[0079]
The system control circuit 50 determines the setting position of the mode dial 60, and if the mode dial 60 is set to power OFF (step S103), the display on each display unit is changed to the end state. Then, the barrier of the protection unit 102 is closed to protect the imaging unit, and necessary parameters, setting values, and setting modes including flags and control variables are recorded in the nonvolatile memory 56. After performing a predetermined end process such as shutting off unnecessary power of each part of the image processing apparatus 100 including the image display unit 28 by the power control unit 80 (step S105), the process returns to step S103.
[0080]
If the mode dial 60 is set to the shooting mode (step S103), the process proceeds to step S106. If the mode dial 60 has been set to another mode (step S103), the system control circuit 50 executes processing corresponding to the selected mode (step S104), and returns to step S103 when the processing is completed. .
[0081]
Here, the operation of closing the barrier of the protection means 102 not shown will be further described.
The system control circuit 50 detects the positions of the variable magnification system lens group 10 and the focusing system lens group 11 in order to store the lens groups 10 and 11 which are not required before operating the protection unit 102 in the camera. If it is determined that the variable magnification lens group 10 is extended, the variable magnification lens group 10 is retracted to the retracted position after the focusing lens group 11 is retracted to the retractable standby position. The process is terminated by closing the barrier of the protection means 102 while synchronizing with the retraction of the variable magnification lens group 10. In this embodiment, the barrier control of the protection means 102 is driven by the independent barrier control means 46, but it is also possible to adopt a system in which it is mechanically driven in conjunction with the driving of the variable magnification system lens group 10. .
[0082]
  The system control circuit 50 has a remaining capacity and operation of the power source 86 constituted by a battery or the like by the power source control means 80.StatusDetermines whether there is a problem in the operation of the image processing apparatus 100 (step S106). If there is a problem, a predetermined warning is displayed by image or sound using the display unit 54 (step S108), and the process returns to step S103. If there is no problem in the power supply 86, the system control circuit 50 determines whether the operation state of the recording medium 200 or 210 has a problem in the operation of the image processing circuit 100, particularly in the recording / reproducing operation of the image data with respect to the recording medium. (Step S107). If there is a problem, a predetermined warning is displayed by image or sound using the display unit 54 (step S108), and the process returns to step S103. If there is no problem in the operation state of the recording medium 200 or 210 (step S107), the display unit 54 is used to display various setting states of the image processing apparatus 100 using images and sounds (step S109). If the image display of the image display unit 28 is ON, the image display unit 28 is also used to display various setting states of the image processing apparatus 100 using images and sounds.
[0083]
The system control circuit 50 checks the image display flag (step S110). If the image display flag is set to ON, the system control circuit 50 performs exposure control (step S116) and proceeds to step S119.
[0084]
If the image display flag is set to OFF (step S110), the setting state of the image display ON / OFF switch 66 is checked (step S111). If the image display is set to ON, the imaging unit is activated. (Step S112), exposure control (Mode = 1) is performed (Step S113). When the proper exposure is obtained, the captured image data is set to the through display state in which the image data is sequentially displayed, the image display of the image display unit 28 is set to the ON state (step S114), and the image display flag is set (step S115). ), The process proceeds to step S119.
[0085]
In the image display state, the data sequentially written in the image display memory 24 via the image pickup device 12, the A / D converter 16, the image processing circuit 20 and the memory control circuit 22 are converted into the memory control circuit 22 and the D / A converter. The electronic finder function is realized by sequentially displaying images on the image display unit 28 via the image display unit 26.
[0086]
If the image display ON / OFF switch 66 is set to image display OFF (step S111), the image display flag is canceled (step S117), and the image display of the image display unit 28 is set to the OFF state (step S111). S118), the process proceeds to step S120. When the image display is OFF, shooting is performed using the optical viewfinder 104 without using the electronic viewfinder function of the image display unit 28. In this case, it is possible to reduce power consumption of the image display unit 28, the D / A converter 26, and the like that consume a large amount of power. The state of the image display flag is stored in the internal memory of the system control circuit 50 or the memory 52.
[0087]
  When automatic exposure control is activated by specifying Mode = 1 in step S113 using the automatic exposure control algorithm, control is performed based on the Bv value obtained by scanning photometry, and the field luminance is measured in a short time. Further, when the automatic exposure control is activated by specifying Mode = 2 without performing any other operation, the photometric ΔBv valueInControl or monitoring is performed accordingly. Although not shown, when control is performed, the control value is obtained from the program diagram after performing division compression according to the magnitude of the photometric ΔBv value. In this way, the brightness of the displayed image is controlled with a certain time constant.
[0088]
In the brightness monitoring state without control, the timer may be started after the brightness change is recognized, and the algorithm may be changed so as to shift to control when the brightness change has occurred even after a predetermined time has elapsed. . Further, the appropriate exposure range in the brightness monitoring state and the appropriate exposure range in the exposure control state may be expanded or narrowed according to the mode without making Modes 1 to 4 the same. In particular, by expanding the exposure monitoring range or the appropriate exposure range in the image display mode (Mode = 2), it is possible to more gently control the luminance change of the image displayed on the image display unit 28 during image display.
[0089]
Subsequently, an operation related to the shooting operation will be described.
If the shutter switch SW1 has not been pressed (step S119), the process returns to step S103. If the shutter switch SW1 is pressed (step S119), the system control circuit 50 determines the state of the image display flag stored in the internal memory of the system control circuit 50 or the memory 52 (step S120). If set, the display state of the image display unit 28 is set to the freeze display state (step S121), and the process proceeds to step S122. In the freeze display state, image data rewriting of the image display memory 24 via the image sensor 12, the A / D converter 16, the image processing circuit 20, and the memory control circuit 22 is prohibited, and the last written image data is By displaying on the image display unit 28 via the memory control circuit 22 and the D / A converter 26, the frozen image is displayed on the electronic viewfinder. If the image display flag is released (step S120), the process proceeds to step S122.
[0090]
This distance measurement / photometry process (step S122) will be described in detail with reference to FIG.
First, the system control circuit 50 checks the setting state of the image display flag (step S201). If it is not set, the system control circuit 50 activates the imaging means (step S202), reads the charge signal from the imaging element 14, and performs A / D. The captured image data is sequentially read into the image processing circuit 20 via the converter 16.
[0091]
Next, the system control circuit 50 activates the automatic exposure control means in the shooting preparation period mode (Mode = 3) (step S203), and sets the distance measurement area in TTLAF to an appropriate exposure (step S204). Subsequently, distance measurement processing by TTLAF is performed to focus the focusing lens 11 on the subject (step S205). Further, the automatic exposure control means is activated in the mode immediately before shooting, and finally the evaluation photometric process is performed on the entire screen to determine the aperture value, shutter time, and imaging sensitivity adjustment value (step S206). After the proper exposure is obtained (step S207), the system control circuit 50 performs AWB control by adjusting the color processing parameters using the image processing circuit 20 until the white balance is determined to be appropriate (step S208). ).
[0092]
If it is determined that the exposure is appropriate, the measurement data and the setting parameters are stored in the internal memory of the system control circuit 50 or the memory 52. Subsequently, the shutter time under the photographing condition during the main exposure is calculated from the Bv value determined by the exposure control. At this time, the program diagram is calculated once by switching to the main exposure, and after the calculation, the original program diagram is restored. At this time, control is not performed only by calculation.
[0093]
When the calculated shutter time is equal to or less than a predetermined (shake limit) value (step S209), if the flash-off mode is set (step S210), the display contents of the display unit 54 are displayed in the optical viewfinder 104. A camera shake warning is displayed (step S211). If it is not in the flash-off mode, EF shooting display is performed (step S212). Even in the mode in which the red-eye mitigation lamp is lit, lighting is started below the camera shake limit. If the camera shake limit is not reached in step S208, AE shooting display is performed (step S213).
[0094]
Further, a flag for the shooting mode determined under the above-described conditions is set (step S214), and a buzzer indicating the completion of shooting preparation is sounded (step S215). After the distance measurement / photometry processing (step S122), the system control circuit 50 determines the state of the image display flag stored in the internal memory of the system control circuit 50 or the memory 52 (step S123). If the image display flag has been set, the display state of the image display unit 28 is set to the through display state (step S124), and the process proceeds to step S125. Note that the through display state in step S124 is the same operation state as the through state in step S115.
[0095]
If the shutter switch SW2 is not pressed (step S125) and the shutter switch SW1 is also released (step S126), the process returns to step S103. A description of the shooting operation after the shutter switch SW2 is pressed will be omitted.
[0096]
By using the first photometry means as described above, the field brightness can be measured within a certain period regardless of the state of the field brightness. In addition, by performing feedback using the output of the second photometric unit after performing photometry with the first photometric unit, it is possible to take a picture in a high-speed and accurate photometric state. Further, the first photometric means is used before the image display and when the image display is not performed and when the preparation for photographing is performed, and the second photometric means for performing photometry at intervals is used otherwise. The integration circuit of the image processing unit can be stopped for a long time, and photometry with low power consumption can be performed in a short time.
[0097]
In addition, by making the dynamic range that can be measured under each control in the first photometric means overlap, photometry that emphasizes the linearity of photometry is possible. Furthermore, by not overlapping the dynamic range that can be metered under each control in the first metering means, it is possible to configure the exposure control that places importance on the consumption time until grasping the field luminance. Further, when it is determined that the result of the photometry calculation by time division within the first photometry period can be photometric within the dynamic range, at least one of the subsequent control, integration and photometry calculations is prohibited. As a result, faster exposure control is possible.
[0098]
In this embodiment, the image display is performed on the image display unit in the apparatus, but a video amplifier and a video signal output terminal are provided in place of the image display unit 28 including a TFT LCD or the like, and a display device outside the apparatus is provided. The same effect can be achieved when displaying or when displaying the image by transferring the image data to an external device using the communication means 110 and the connector 112.
[0099]
The present invention provides software for realizing the functions of the above-described embodiments for a computer in an apparatus or a system connected to the various devices so that the various devices are operated so as to realize the functions of the above-described embodiments. What is implemented by supplying the program code and operating the various devices according to a program stored in a computer (CPU or MPU) of the system or apparatus is also included in the scope of the present invention.
[0100]
In this case, the program code of the software itself realizes the functions of the above-described embodiments, and the program code itself and means for supplying the program code to the computer, for example, the program code is stored. The storage medium constitutes the present invention. As a storage medium for storing the program code, for example, a floppy disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.
[0101]
Further, by executing the program code supplied by the computer, not only the functions of the above-described embodiments are realized, but also the OS (operating system) or other application software in which the program code is running on the computer, etc. The program code is also included in the embodiment of the present invention when the functions of the above-described embodiment are realized in cooperation with the above.
[0102]
Further, after the supplied program code is stored in the memory provided in the function expansion board of the computer or the function expansion unit connected to the computer, the CPU provided in the function expansion board or function expansion unit based on the instruction of the program code Etc. perform part or all of the actual processing, and the functions of the above-described embodiments are realized by the processing.
[0103]
【The invention's effect】
  As described above, according to the present invention, when automatic exposure control is performed using the output of the solid-state imaging device, the photographing preparation operation period is shortened and the stable time is reached regardless of the state of the electronic viewfinder. Exposure control for performing photometry and exposure becomes possible. As a comprehensive effect of the present invention, power consumption and release time lag are reduced, and shutter timing is not missed.Such as electronic camerasAn advantage is that the image processing apparatus can be configured.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an apparatus configuration according to an embodiment of the present invention.
FIG. 2 is a flowchart showing a main routine in the embodiment of the present invention.
FIG. 3 is a flowchart showing a main routine in the embodiment of the present invention.
FIG. 4 is a flowchart showing a distance measurement / photometry routine in the embodiment of the present invention.
FIG. 5 is a flowchart of exposure control in the embodiment of the present invention.
FIG. 6 is a flowchart of exposure control processing according to the embodiment of the present invention.
FIG. 7 is a flowchart of photometry in the embodiment of the present invention.
FIG. 8 is a flowchart of a first photometric operation in the embodiment of the present invention.
FIG. 9 is a flowchart of a second photometric operation in the embodiment of the present invention.
FIG. 10 is a timing chart of a first photometric operation in the embodiment of the present invention.
FIG. 11 is a timing chart of a second photometric operation in the embodiment of the present invention.
FIG. 12 is a diagram showing a configuration of automatic exposure control in the embodiment of the present invention.
[Explanation of symbols]
10 Zoom lens
11 Focusing lens
12 Shutter
14 Image sensor
15 Imaging sensitivity adjustment means
16 A / D converter
18 Timing generator
20 Image processing circuit
22 Memory control circuit
24 Image display memory
26 D / A converter
28 Image display
30 memory
32 Image compression / decompression circuit
40 Automatic exposure control means
42 Ranging control means
44 Zoom control means
46 Barrier control means
48 flash
50 System control circuit
52 memory
54 Display
56 Nonvolatile memory
60 mode dial switch
62 Shutter switch SW1
64 Shutter switch SW2
66 Image display ON / OFF switch
67 Variable magnification lens drive direction switch (Tele)
68 Quick review ON / OFF switch
69 Variable magnification lens drive direction switch (Wide)
70 Operation unit
80 Power control means
82 connector
84 connector
86 Power supply means
90 interface
92 connector
94 interface
96 connectors
98 Recording medium attachment / detachment detection means
100 Image processing apparatus
102 Protective measures
104 Optical viewfinder
110 Communication means
112 connector (or antenna)
200 recording media
202 Recording unit
204 interface
206 Connector
210 Recording medium
212 Recording unit
214 interface
216 connector

Claims (4)

Photoelectric conversion means for converting an optical image into an electrical signal;
Display means for displaying an image based on the electrical signal converted by the photoelectric conversion means;
Photometric means for determining the field luminance based on the electrical signal converted by the photoelectric conversion means;
Exposure control means for performing exposure control based on a photometric result of the photometry means;
First photometry for obtaining a plurality of field luminances based on the electrical signal obtained by performing exposure a plurality of times under different exposure conditions in a plurality of vertical synchronization periods, and exposure once in the plurality of vertical synchronization periods Control means for controlling the photometry means so as to perform any one of the second photometry for obtaining the field luminance based on the electric signal obtained by performing
The control means performs the first photometry when the images are not sequentially displayed on the display means, and repeatedly performs the second photometry while the images are sequentially displayed on the display means. Controlling the photometric means,
The exposure control means selects and selects one field brightness from the plurality of field brightnesses determined by the first metering when the light metering means performs the first metering. An image processing apparatus that performs exposure control based on the field luminance. The control means controls the photometry means to perform the first photometry before the sequential display of the images is started when the images are sequentially displayed on the display means. Item 8. The image processing apparatus according to Item 1. When the image is sequentially displayed on the display unit, the photometry unit performs the second photometry based on the result of the first photometry performed before the sequential display of the image is started. The image processing apparatus according to claim 1, wherein the image processing apparatus is characterized. A photoelectric conversion means for converting an optical image into an electric signal, a display means for displaying an image based on the electric signal converted by the photoelectric conversion means, and a field luminance based on the electric signal converted by the photoelectric conversion means. A method for controlling an image processing apparatus, comprising:
An exposure control step for performing exposure control based on a photometric result of the photometric means;
First photometry for obtaining a plurality of field luminances based on the electrical signal obtained by performing exposure a plurality of times under different exposure conditions in a plurality of vertical synchronization periods, and exposure once in the plurality of vertical synchronization periods A control step for controlling the photometry means so as to perform any one of the second photometry for obtaining the field luminance based on the electric signal obtained by performing
In the control step, the first photometry is performed when the image is not sequentially displayed on the display unit, and the second photometry is repeatedly performed while the image is sequentially displayed on the display unit. Controlling the photometric means,
In the exposure control step, when the photometry means performs the first photometry, one field luminance is selected from the plurality of field luminances obtained by the first photometry. A control method for an image processing apparatus, wherein exposure control is performed based on the field luminance.

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