JP4636739B2 - IMAGING DEVICE, IMAGING DEVICE CONTROL METHOD, PROGRAM, AND COMPUTER-READABLE STORAGE MEDIUM - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an imaging device having an automatic exposure mechanism, a control method for the imaging device, a program, and a computer-readable storage medium.
[0002]
[Prior art]
Conventionally, cameras that automatically control exposure and record still images and moving images are commercially available. According to these cameras, even if the user does not operate the aperture or shutter speed, the camera automatically determines the exposure, and the user can take a picture without being aware of the exposure. It has become.
[0003]
[Problems to be solved by the invention]
In such a conventional camera, for a shooting situation in which a high brightness portion exists in a wide area such as a snowy landscape or a cloud, the high brightness portion may be underexposed.
[0004]
As a method for avoiding this, when the integrated value of the luminance level of each photometric area exceeds a predetermined value, the weighting of the photometric area is reduced to prevent underexposure.
[0005]
By the way, even when shooting snow scenes or clouds, white with low brightness may be occupied. In this case, in the above method, since the integrated value of the luminance level of each photometric area does not exceed a predetermined value, the weighting of the photometric area remains as it is, and the exposure is determined because the luminance is considered low. There is a possibility.
[0006]
The present invention has been made in view of the above points, and an object of the present invention is to prevent underexposure even when a low brightness white occupies most of the photometric area.
[0007]
[Means for Solving the Problems]
An imaging apparatus according to the present invention is an imaging apparatus having an automatic exposure mechanism, and a dividing unit that divides captured image data into a plurality of areas, and an exposure evaluation value generation that generates an exposure evaluation value based on luminance for each of the areas. Means, color evaluation value generation means for generating a color evaluation value for each part in each area, and the color evaluation value is within a predetermined range of the color temperature distribution in each area. White Number of parts Is the first number, compared to the case where the number of white portions is a second number smaller than the first number, Weighting the exposure evaluation value for the area Make smaller A weight determining unit; and an exposure control unit that performs a weighting operation on the exposure evaluation value of each area using the weight determined by the weight determining unit, and performs exposure control based on a result of the weighting operation. It has the characteristics.
[0010]
Another feature of the imaging apparatus according to the present invention is that the color evaluation value generation means generates the color evaluation value for each pixel in each area.
[0011]
An image pickup apparatus control method according to the present invention is an image pickup apparatus control method provided with an automatic exposure mechanism, and a division procedure for dividing captured image data into a plurality of areas, and an exposure evaluation value based on luminance for each of the areas. The generated exposure evaluation value generation procedure, the color evaluation value generation procedure for generating the color evaluation value for each part in each area, and the color evaluation value within the predetermined range of the color temperature distribution in each area. White Number of parts Is the first number, compared to the case where the number of white portions is a second number smaller than the first number, Weighting the exposure evaluation value for the area Make smaller A weight determination procedure, and an exposure control procedure for performing a weight calculation on the exposure evaluation value of each area using the weight determined by the weight determination procedure and performing an exposure control based on a result of the weight calculation. Has characteristics.
[0013]
The program of the present invention is a program for controlling an image pickup apparatus equipped with an automatic exposure mechanism, and generates a division processing for dividing captured image data into a plurality of areas and an exposure evaluation value based on luminance for each of the areas. Exposure evaluation value generation processing to be performed, and when the number of portions in which the color evaluation value falls within a predetermined range of the color temperature distribution and is white in each area is the first number, Compared to the case where the number is a second number smaller than the first number, the weight determination process for reducing the weight for the exposure evaluation value of the area and the weights determined by the weight determination process are used for each of the above. An exposure control process that performs a weighting operation on the exposure evaluation value of the area and performs exposure control based on the result of the weighting operation. On the computer It is characterized in that it is executed.
[0015]
The computer-readable storage medium of the present invention is characterized in that the program is stored.
[0016]
In the present invention as described above, the exposure evaluation value for each area is generated based on the luminance, and the exposure calculation value is weighted based on the color information in each area. Even when most of the area is white with low brightness, it is possible to prevent underexposure.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of an imaging apparatus, an imaging apparatus control method, a program, and a computer-readable storage medium according to the present invention will be described with reference to the drawings.
[0018]
FIG. 1 is a block diagram illustrating a configuration example of a digital camera according to the present embodiment. In the figure, reference numeral 10 denotes a photographic lens, 12 denotes a shutter having a diaphragm function, and 14 denotes an image sensor that converts an optical image into an electric signal.
[0019]
Reference numeral 16 denotes an A / D converter that converts an analog signal output from the image sensor 14 into a digital signal. A timing generation circuit 18 supplies a clock signal and a control signal to the image sensor 14, the A / D converter 16, and the D / A converter 26, and is controlled by the memory control circuit 22 and the system control circuit 50.
[0020]
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. Further, the image processing circuit 20 performs predetermined calculation processing using the captured image data, and the system control circuit 50 controls the exposure control unit 40 and the distance measurement control means 42 based on the obtained calculation result. TTL (through-the-lens) AF (autofocus) processing, AE (automatic exposure) processing, and EF (flash pre-flash) processing. 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.
[0021]
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. Data of the A / D converter 16 is written to the image display memory 24 or the memory 30 via the image processing circuit 20 and the memory control circuit 22 or directly via the memory control circuit 22.
[0022]
Reference numeral 24 denotes an image display memory, 26 denotes a D / A converter, and 28 denotes an image display unit composed of a TFT LCD or the like. Display image data written in the image display memory 24 passes through the D / A converter 26. Are displayed by the image display unit 28. An electronic viewfinder function can be realized by sequentially displaying image data captured using the image display unit 28. 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 digital camera can be greatly reduced. .
[0023]
Reference numeral 30 denotes a memory for storing captured still images and moving images, and has a sufficient storage capacity to store a predetermined number of still images and a predetermined time of moving images. Thereby, even in the case of continuous shooting or panoramic shooting in which a plurality of still images are continuously shot, it is possible to write a large amount of images to the memory 30 at high speed. The memory 30 can also be used as a work area for the system control circuit 50.
[0024]
Reference numeral 32 denotes a compression / decompression circuit that compresses and decompresses image data by adaptive discrete cosine transform (ADCT) or the like, reads an image stored in the memory 30, performs compression processing or decompression processing, and stores the processed data in the memory 30. Write to.
[0025]
Reference numeral 40 denotes an exposure control unit that controls the shutter 12 having a diaphragm function, and has a flash light control function in cooperation with the flash 48. Reference numeral 42 denotes a distance measurement control unit that controls focusing of the photographing lens 10, reference numeral 44 denotes a zoom control unit that controls zooming of the photographing lens 10, and reference numeral 46 denotes a barrier control unit that controls the operation of the protection means 102 serving as a barrier. A flash 48 has an AF auxiliary light projecting function and a flash light control function. The exposure control unit 40 and the distance measurement control unit 42 are controlled using the TTL method. Based on the calculation result obtained by calculating the captured image data by the image processing circuit 20, the system control circuit 50 performs the exposure control unit 40 and the distance measurement. The controller 42 is controlled.
[0026]
Reference numeral 50 denotes a system control circuit that controls the entire system, and reference numeral 52 denotes a memory that stores constants, variables, programs, and the like for operation of the system control circuit 50.
[0027]
Reference numeral 54 denotes a display unit such as a liquid crystal display device or a speaker that displays an operation state or a message using characters, images, sounds, or the like in accordance with execution of a program in the system control circuit 50. In the vicinity of the operation unit of the digital camera One or a plurality of positions are installed at a position where it is easy to visually recognize, and for example, it is configured by a combination of an LCD, an LED, a sound generation element, and the like. In addition, the display unit 54 is partially installed in the optical viewfinder 104.
[0028]
Among the display contents of the display unit 54, what is displayed on the LCD or the like includes single shot / continuous shooting display, self-timer display, compression rate display, number of recorded pixels, number of recorded pixels, number of remaining shots, shutter Speed display, Aperture value display, Exposure compensation display, Flash display, Red-eye reduction display, Macro shooting display, Buzzer setting display, Clock battery level display, Battery level display, Error display, Multi-digit number information display and recording There are a display state of the media 200 and 210, a communication I / F operation display, a date / time display, and the like.
[0029]
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.
[0030]
Reference numeral 56 denotes an electrically erasable / recordable nonvolatile memory, such as an EEPROM.
[0031]
Reference numerals 60, 62, 64, 66, 68 and 70 are operation means for inputting various operation instructions of the system control circuit 50, and may be 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.
[0032]
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.
[0033]
Reference numeral 62 denotes a shutter switch SW1, which is turned ON during the operation of a shutter button (not shown), and performs AF (auto focus) processing, AE (auto exposure) processing, AWB (auto white balance) processing, EF (flash pre-flash) processing, and the like. Instruct to start operation. Reference numeral 64 denotes a shutter switch SW2, which is turned on when the operation of a shutter button (not shown) is completed, and an exposure process for writing a signal read from the image sensor 12 to the memory 30 via the A / D converter 16 and the memory control circuit 22. Development processing using operations in the image processing circuit 20 and the memory control circuit 22, recording processing for reading image data from the memory 30, compression in the compression / decompression circuit 32, and writing the image data to the recording medium 200 or 210. Instructs the start of a series of processing operations.
[0034]
Reference numeral 66 denotes an image display ON / OFF switch, which can set ON / OFF of the image display unit 28. With this function, when taking an image using the optical viewfinder 104, it is possible to save power by cutting off the current supply to the image display unit 28 including a TFT LCD or the like.
[0035]
Reference numeral 68 denotes a quick review ON / OFF switch, which sets a quick review function for automatically reproducing image data taken immediately after photographing. In the present embodiment, it is assumed that a function for setting a quick review function when the image display unit 28 is turned off is provided.
[0036]
Reference numeral 70 denotes an operation unit composed of various buttons, a touch panel, and the like. A menu button, a set button, a macro button, a multi-screen playback page break button, a flash setting button, a single shooting / continuous shooting / self-timer switching button, menu movement + (plus) Button, menu shift- (minus) button, playback image shift + (plus) button, playback image- (minus) button, shooting image quality selection button, exposure correction button, date / time setting button, and the like.
[0037]
Reference numeral 80 denotes a power supply control unit, which includes a battery detection circuit, a DC-DC converter, a switch circuit that switches a block to be energized, and the like, and detects the presence / absence of a battery, the type of battery, the remaining battery level, In addition, the DC-DC converter is controlled based on an instruction from the system control circuit 50, and a necessary voltage is supplied to each part including the recording medium for a necessary period.
[0038]
Reference numeral 82 denotes a connector, 84 denotes a connector, and 86 denotes a power source 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, an AC adapter, or the like.
[0039]
90 and 94 are interfaces with a recording medium such as a memory card or a hard disk, 92 and 96 are connectors for connecting to a recording medium such as a memory card or a hard disk, and 98 is a recording medium 200 or 210 attached to the connector 92 or 96. Recording medium attachment / detachment detecting means for detecting whether or not the recording medium is present.
[0040]
In the present embodiment, the description has been made assuming that there are two interfaces and connectors to which the recording medium is attached. Of course, the interface and connector to which the recording medium is attached may have a single or plural number of systems. It doesn't matter. In addition, a combination of interfaces and connectors of different standards may be provided.
[0041]
The interface and the connector may be configured using a PCMCIA card, a CF (Compact Flash (R)) card, or the like that conforms to a standard. In addition, when the interfaces 90 and 94 and the connectors 92 and 96 are configured using a PCMCIA card or a CF (Compact Flash (R)) card or the like, LAN cards, modem cards, USB cards, IEEE1394 cards By connecting various communication cards such as communication cards such as P1284 card, SCSI card, PHS, etc., image data and management information attached to image data can be transferred to and from peripheral devices such as other computers and printers. Can fit.
[0042]
A protection unit 102 is a barrier that covers the imaging unit including the lens 10 to prevent the imaging unit from being dirty or damaged. 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. Further, in the optical viewfinder 104, some functions of the display unit 54, for example, a match point display, a camera shake warning display, a flash charge display, a shutter speed display, an aperture value display, an exposure correction display, and the like are installed.
[0043]
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 digital camera to other devices by the communication means 110 or an antenna in the case of wireless communication.
[0044]
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 a digital camera, and a connector 206 for connecting with the digital camera.
[0045]
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 a digital camera, and a connector 216 for connecting with the digital camera.
[0046]
Hereinafter, processing operations in the digital camera according to the above embodiment will be described with reference to FIGS.
[0047]
2 and 3 show a flowchart of the main routine. 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 on the image display unit 28 to an OFF state (step S102).
[0048]
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 of each display unit is changed to the end state, and the protection means 102 The image capturing unit is protected by closing the barrier, and necessary parameters, setting values, and setting modes including flags and control variables are recorded in the non-volatile memory 56, and each unit of the digital camera including the image display unit 28 is controlled by the power control unit 80. After performing a predetermined end process such as shutting off unnecessary power (step S105), the process returns to step S103.
[0049]
If the mode dial 60 is set to the photographing mode (step S103), the process proceeds to step S106. If the mode dial 60 has been set to another mode (step S103), the process according to the selected mode is executed (step S104). If the process is completed, the process returns to step S103.
[0050]
The system control circuit 50 determines whether there is a problem in the operation of the digital camera in terms of the remaining capacity and operation status of the power source 86 constituted by a battery or the like by the power control means 80 (step S106). Then, after a predetermined warning is displayed by image or sound using the display unit 54 (step S108), the process returns to step S103. If there is no problem with the power source 86 (step S106), it is determined whether the operation state of the recording medium 200 or 210 has a problem with the operation of the image processing apparatus 100, particularly with respect to the recording / reproducing operation of the image data with respect to the recording medium ( In step S107), if there is a problem, a predetermined warning is displayed by image or sound using the display unit 54 (step S108), and then the process returns to step S103.
[0051]
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.
[0052]
The system control circuit 50 checks the setting state of the quick review ON / OFF switch 68 (step S110), sets the quick review flag if it is set to quick review ON (step S111), and sets the quick review OFF. If so, the quick review flag is canceled (step S112). The state of the quick review flag is stored in the internal memory of the system control circuit 50 or the memory 52.
[0053]
Subsequently, the system control circuit 50 checks the setting state of the image display ON / OFF switch 66 (step S113). If the image display is set to ON, the system control circuit 50 sets an image display flag (step S114) and the image. The image display on the display unit 28 is set to the ON state (step S115), and further, the captured image data is set to the through display state for sequentially displaying (step S116), and the process proceeds to step S119 in the flowchart of FIG.
[0054]
In the through display state, the data sequentially written in 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 are transferred to the memory control circuit 22 and the D / A. An electronic viewfinder function is realized by sequentially displaying images on the image display unit 28 via the converter 26.
[0055]
If the image display ON / OFF switch 66 is set to image display 0FF (step S113), 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 S117). Step S118), the process proceeds to step S119 in the flowchart of FIG.
[0056]
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.
[0057]
If the shutter switch SW1 has not been pressed (step S119), the system control circuit 50 returns to step S103 in the flowchart of FIG. If the shutter switch SW1 is pressed (step S119), the state of the image display flag stored in the internal memory of the system control circuit 50 or the memory 52 is determined (step S120), and if the image display flag is set. For example, 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.
[0058]
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 the image on the image display unit 28 via the memory control circuit 22 and the D / A converter 26, the frozen video is displayed on the electronic viewfinder.
[0059]
If the image display flag has been canceled (step S120), the process proceeds to step S122. The system control circuit 50 performs a distance measurement process to focus the photographing lens 10 on the subject, performs a photometry process, and determines an aperture value and a shutter time (step S122). In the photometric process, the flash is set if necessary. Details of the distance measurement / photometry processing (step S122) will be described later with reference to the flowchart of FIG.
[0060]
After completing 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), and displays the image. If the 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 operating state as the through state in step S116.
[0061]
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 in the flowchart of FIG.
[0062]
If the shutter switch SW2 is pressed (step S125), 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 S127), and the image display flag. Is set, the display state of the image display unit 28 is set to the fixed color display state (step S128), and the process proceeds to step S129.
[0063]
In the fixed color display state, instead of the captured image data written in 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, the fixed color of the replaced color is displayed. By displaying the image data on the image display unit 28 via the memory control circuit 22 and the D / A converter 26, a fixed color image is displayed on the electronic viewfinder.
[0064]
If the image display flag has been canceled (step S127), the process proceeds to step S129. The system control circuit 50 captures an image in the memory 30 via the image sensor 12, the A / D converter 16, the image processing circuit 20, the memory control circuit 22, or directly from the A / D converter via the memory control circuit 22. An exposure process for writing the image data, and a photographing process including a development process for reading out the image data written in the memory 30 and performing various processes using the memory control circuit 22 and, if necessary, the image processing circuit 20. Execute (Step S129). Details of this photographing process (step S129) will be described later with reference to the flowchart of FIG.
[0065]
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 S130), and if the image display flag is set, performs a quick review display (step S130). S133). In this case, the image display unit 28 is always displayed as an electronic viewfinder even during shooting, and quick review display immediately after shooting is also performed.
[0066]
If the image display flag has been canceled (step S130), the state of the quick review flag stored in the internal memory of the system control circuit 50 or the memory 52 is determined (step S131), and the quick review flag has been set. Then, the image display of the image display unit 28 is set to the ON state (step S132), and quick review display is performed (step S133).
[0067]
As described above, since the electronic viewfinder function is not necessary because the image is taken for power saving or using the optical viewfinder 104, the quick review switch can be used even when the image display of the image display unit 28 is set to OFF. If the quick review function is set, it is possible to automatically reproduce the captured image on the image display unit 28 immediately after shooting, and provide a power saving and a convenient function for confirming the captured image. It becomes possible.
[0068]
If the image display flag is released (step S130) and the quick review flag is also released (step S131), the process proceeds to step S134 while the image display unit 28 is in an OFF state. In this case, the image display unit 28 remains off even after shooting, and no quick review display is performed. This is a usage method in which it is not necessary to check a photographed image immediately after photographing as in the case of continuing photographing using the optical viewfinder 104, and the power saving is emphasized without using the electronic finder function of the image display unit 28. .
[0069]
The system control circuit 50 reads the captured image data written in the memory 30 and performs various image processing using the memory control circuit 22 and, if necessary, the image processing circuit 20, and also uses the compression / decompression circuit 32. After performing the image compression process according to the set mode, the recording process for writing the image data to the recording medium 200 or 210 is executed (step S134). Details of this recording process (step S134) will be described later with reference to the flowchart of FIG.
[0070]
If the shutter switch SW2 has been pressed when the recording process (step S134) is completed (step S135), the system control circuit 50 is stored in the internal memory of the system control circuit 50 or the memory 52. The state of the continuous shooting flag is determined (step S136). If the continuous shooting flag is set, the flow returns to step S129 to perform continuous shooting, and the next shooting is performed.
[0071]
If the continuous shooting flag is not set (step S136), the current process is repeated until the shutter switch SW2 is released (step S135).
[0072]
The shutter switch SW2 was released when the recording process (step S134) was completed, or the shutter switch SW2 was kept pressed to continue the quick review display to confirm the captured image, and then the shutter switch SW2 If the state is released (step S135), the process proceeds to step S138 after a predetermined minimum review time has elapsed (step S137).
[0073]
As described above, by continuing the quick review display in the image display unit 28 for a predetermined time, it is possible to surely check the captured image, and to continue the quick review display unnecessarily for a long time. Can prevent you from losing your shooting chance. The minimum review time can be a fixed value, can be arbitrarily set by the user, or can be arbitrarily set or selected by the user within a predetermined range. It does not matter if it is set by the method
[0074]
If the image display flag has been set (step S138), the system control circuit 50 sets the display state of the image display unit 28 to the through display state (step S139), and proceeds to step S141. In this case, after confirming the captured image by the quick review display on the image display unit 28, it is possible to enter a through display state in which image data captured for the next imaging is sequentially displayed.
[0075]
If the image display flag has been canceled (step S138), the image display of the image display unit 28 is set to the OFF state (step S140), and the process proceeds to step S141. In this case, after confirming the photographed image by the quick review display on the image display unit 28, the function of the image display unit 28 is stopped for power saving, and the image display unit 28 or D / A conversion with large power consumption is stopped. It is possible to reduce the power consumption of the device 26 and the like.
[0076]
If the shutter switch SW1 has been pressed (step S141), the system control circuit 50 returns to step S125 to prepare for the next shooting. If the shutter switch SW1 has been released (step S141), the system control circuit 50 ends the series of shooting operations and returns to step S103 in the flowchart of FIG.
[0077]
FIG. 4 shows a detailed flowchart of the distance measurement / photometry process in step S122 of the flowchart of FIG. The system control circuit 50 reads the charge signal from the image sensor 14 and sequentially reads the captured image data into the image processing circuit 20 via the A / D converter 16 (step S201). The read image data is divided into a plurality of sampling areas, the exposure evaluation value is weighted for each area, and the exposure evaluation is calculated. If the total number of pixels whose color evaluation values are within the predetermined range of the color temperature distribution in each area exceeds the predetermined number, the exposure evaluation value in the sampling area is reduced in weight. Details of the photometric evaluation process (step S201) will be described later with reference to the flowchart of FIG.
[0078]
Using the sequentially read image data, the image processing circuit 20 is used for predetermined TTL (through the lens) AE (automatic exposure) processing, EF (flash pre-flash) processing, and AF (autofocus) processing. The operation is performed. In each processing here, a specific portion of the total number of photographed pixels is extracted by extracting a necessary portion according to necessity and used for calculation. This makes it possible to perform optimum computation for each different mode such as the center-weighted mode, the average mode, and the evaluation mode in each of the TTL AE, EF, AWB, and AF processes.
[0079]
Using the calculation result in the image processing circuit 20, the system control circuit 50 performs AE control using the exposure control unit 40 (step S203) until it is determined that the exposure (AE) is appropriate (step S202).
[0080]
Using the measurement data obtained by the AE control, the system control circuit 50 determines whether or not the flash is necessary (step S204). If the flash is necessary, the flash control is set and the flash 48 is charged (step S204). S205).
[0081]
If it is determined that the exposure (AE) is appropriate (step S202), the measurement data and / or setting parameters are stored in the internal memory of the system control circuit 50 or the memory 52.
[0082]
The system control circuit 50 uses the image processing circuit 20 until the white balance (AWB) is determined to be appropriate (step S206) using the calculation result in the image processing circuit 20 and the measurement data obtained by the AE control. The color processing parameters are adjusted to perform AWB control (step S207).
[0083]
If it is determined that the white balance (AWB) is appropriate (step S206), the measurement data and / or setting parameters are stored in the internal memory of the system control circuit 50 or the memory 52.
[0084]
Using the measurement data obtained by the AE control and the AWB control, the system control circuit 50 performs the AF control using the distance measurement control unit 42 until the distance measurement (AF) is determined to be a match point (step S208). (Step S209).
[0085]
If the distance measurement (AF) is determined to be the point (step S208), the measurement data and / or the setting parameters are stored in the internal memory of the system control circuit 50 or the memory 52, and the distance measurement / photometry processing routine (step S122) is executed. finish.
[0086]
FIG. 5 shows a detailed flowchart of the photographing process in step S129 of the flowchart of FIG. The system control circuit 50 exposes the image sensor 10 by opening the shutter 12 having an aperture function according to the aperture value by the exposure control unit 40 according to the photometric data stored in the internal memory of the system control circuit 50 or the memory 52. (Steps S301 and S302).
[0087]
It is determined whether or not the flash 48 is necessary based on the flash flag (step S303). If necessary, the flash 48 is caused to emit light (step S304).
[0088]
The system control circuit 50 waits for the end of exposure of the image sensor 12 according to the photometric data (step S305), closes the shutter 12 (step S306), reads out the charge signal from the image sensor 14, and performs the A / D converter 16 and image processing. The photographed image data is written into the memory 30 via the circuit 20, the memory control circuit 22, or directly from the A / D converter 16 via the memory control circuit 22 (step S307).
[0089]
If it is necessary to perform frame processing according to the set shooting mode (step S308), the system control circuit 50 writes into the memory 30 using the memory control circuit 22 and, if necessary, the image processing circuit 20. The read image data is read out, the vertical addition process (step S309) and the color process (step S310) are sequentially performed, and the processed image data is written in the memory 30.
[0090]
The system control circuit 50 reads the image data from the memory 30 and transfers the display image data to the image display memory 24 via the memory control circuit 22 (step S311). When the series of processing is finished, the photographing processing routine (step S129) is finished.
[0091]
FIG. 6 shows a detailed flowchart of the recording process in step S134 of the flowchart of FIG. The system control circuit 50 reads out the captured image data written in the memory 30 using the memory control circuit 22 and, if necessary, the image processing circuit 20, and interpolates the vertical / horizontal pixel ratio of the image sensor to 1: 1. After performing the square processing (step S401), the processed image data is written in the memory 30.
[0092]
The image data written in the memory 30 is read out and subjected to image compression processing by the compression / decompression circuit 32 corresponding to the set mode (step S402), and then via the interface 90 or 94 and the connector 92 or 96. Then, the compressed image data is written to the recording medium 200 or 210 such as a memory card or a compact flash (R) card (step S403). When the writing to the recording medium is finished, the recording processing routine (step S134) is ended.
[0093]
FIG. 7 shows a detailed flowchart of the photometric evaluation process in step S201 of the flowchart of FIG. The system control circuit 50 reads the charge signal from the image sensor 14 and sequentially reads the captured image data into the image processing circuit 20 via the A / D converter 16 (step S501). Processing is performed for each sampling area from the read image.
[0094]
In each sampling area, first, an exposure evaluation value is generated from luminance information (luminance level) (step S502).
[0095]
Next, a color evaluation value, which is a signal that can determine the hue of the pixels in each sampling area, is generated from the color information signal level (for example, the color difference signal CR / CB is color-evaluated from the color level (RGB or the like). (Step S503), the total number of pixels whose color evaluation value is within the predetermined range of the color temperature distribution is counted, and if the total number is within the predetermined number (Step S504), the weight of the area is set in advance. The set value is set (step S505). On the other hand, if the total number exceeds the predetermined number, the weight of the area is set to a value smaller than a value that is normally set (step S506). That is, the predetermined range and the predetermined number are set so that it is possible to determine whether each area is white (whether there are many white pixels), and in the white area (area where there are many white pixels), exposure evaluation is performed. The weight of the value is made small.
[0096]
This series of processes is performed for all sampling areas, and the weighted exposure evaluation values are added to calculate the overall exposure evaluation value (step S508). When the overall exposure evaluation value is calculated, the exposure evaluation value calculation routine (step S201) is terminated. In the present embodiment, the system control circuit 50 corresponds to each means such as an exposure evaluation value generation means and a color evaluation value generation means referred to in the present invention.
[0097]
As described above, the exposure evaluation value for each area is generated based on the luminance, and the exposure evaluation value is weighted based on the color information in each area. Even when white with low brightness occupies, it is possible to prevent underexposure.
[0098]
In the present embodiment, the total number of pixels whose color evaluation values are within a predetermined range of the color temperature distribution is counted, but the predetermined range is arbitrarily set by the user even if it is a fixed value. Even if it is possible, the user can arbitrarily set or select within a predetermined range, or any method may be used.
[0099]
In addition, it is determined whether the total number of pixels whose color evaluation value is within the predetermined range of the color temperature distribution exceeds the predetermined number. However, the predetermined number can be set as a fixed value by the user. It can be set by any method, even if the user can arbitrarily set or select within a predetermined range.
[0100]
Furthermore, the total number of pixels whose color evaluation value is within the predetermined range is not only changed in two stages, such as changing the weighting when the total number of pixels within the predetermined range of the color temperature distribution exceeds the predetermined number. Depending on, the weighting value may be changed in more stages.
[0101]
(Other embodiments)
Software program for realizing the functions of the above-described embodiment for an apparatus or a computer in the system connected to the various devices so as to operate the various devices to realize the functions of the above-described embodiments. What was implemented by supplying the code and operating the various devices in accordance with a program stored in a computer (CPU or MPU) of the system or apparatus is also included in the scope of the present invention.
[0102]
In this case, the program code of the software itself realizes the functions of the above-described embodiments, and the program code itself constitutes the present invention. As a transmission medium of the program code, a communication medium (wired line or wireless line such as an optical fiber) in a computer network (LAN, WAN such as the Internet, wireless communication network, etc.) system for propagating and supplying program information as a carrier wave Etc.) can be used.
[0103]
Further, means for supplying the program code to the computer, for example, a recording medium storing the program code constitutes the present invention. As a recording medium for storing the program code, for example, a flexible 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.
[0104]
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. Needless to say, the program code is also included in the embodiment of the present invention even when the functions of the above-described embodiment are realized in cooperation with the above.
[0105]
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 Needless to say, the present invention also includes the case where the functions of the above-described embodiment are realized by performing part or all of the actual processing.
[0106]
It should be noted that the shapes and structures of the respective parts shown in the above embodiments are merely examples of implementation in carrying out the present invention, and these limit the technical scope of the present invention. It should not be interpreted. That is, the present invention can be implemented in various forms without departing from the spirit or main features thereof.
[0107]
【The invention's effect】
As described above, according to the present invention, it is possible to prevent the underexposure even when the white area having a low luminance occupies most of the photometric area, and to provide an imaging apparatus with an enhanced automatic exposure function. Can be provided.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of a digital camera.
FIG. 2 is a flowchart showing a main routine of processing operations of the digital camera of the present embodiment.
FIG. 3 is a flowchart showing a main routine of processing operations of the digital camera of the present embodiment.
FIG. 4 is a flowchart showing a distance measurement / photometry processing routine.
FIG. 5 is a flowchart illustrating an imaging processing routine.
FIG. 6 is a flowchart showing a recording processing routine.
FIG. 7 is a flowchart showing a photometric evaluation processing routine.
[Explanation of symbols]
12 Shutter with aperture function
14 Image sensor
18 Timing generator
20 Image processing circuit
40 Metering control unit
50 System control circuit

Claims (5)

An imaging device equipped with an automatic exposure mechanism,
A dividing means for dividing the photographed image data into a plurality of areas;
Exposure evaluation value generating means for generating an exposure evaluation value based on luminance for each area;
Color evaluation value generation means for generating a color evaluation value for each part in each area,
In each area, when the color evaluation value is within a predetermined range of the color temperature distribution and the number of white portions is the first number, the number of white portions is greater than the first number. A weight determination means for reducing the weight for the exposure evaluation value of the area as compared with the case of the small second number;
An exposure control means for performing a weighting operation on the exposure evaluation value of each area using the weighting determined by the weighting determination means and performing exposure control based on a result of the weighting calculation. apparatus.   The imaging apparatus according to claim 1, wherein the color evaluation value generation unit generates the color evaluation value for each pixel in each area. A method for controlling an imaging apparatus having an automatic exposure mechanism,
A division procedure for dividing the captured image data into a plurality of areas;
An exposure evaluation value generation procedure for generating an exposure evaluation value based on luminance for each area,
A color evaluation value generation procedure for generating a color evaluation value for each part in each area;
In each area, when the color evaluation value is within a predetermined range of the color temperature distribution and the number of white portions is the first number, the number of white portions is greater than the first number. A weighting determination procedure for reducing the weighting for the exposure evaluation value of the area as compared with the case of the small second number;
An exposure control procedure for performing a weighting operation on the exposure evaluation value of each area using the weighting determined by the weighting determination procedure, and performing an exposure control based on a result of the weighting operation. Control method. A program for controlling an imaging apparatus equipped with an automatic exposure mechanism,
A division process for dividing the captured image data into a plurality of areas;
Exposure evaluation value generation processing for generating an exposure evaluation value based on luminance for each area;
In each area, when the color evaluation value is within a predetermined range of the color temperature distribution and the number of white portions is the first number, the number of white portions is greater than the first number. A weighting determination process for reducing the weighting for the exposure evaluation value of the area as compared with the case where the second number is small;
A weight calculation is performed on the exposure evaluation value of each area using the weight determined by the weight determination process, and an exposure control process for performing exposure control based on a result of the weight calculation is executed by the computer. Program to do.   A computer-readable storage medium storing the program according to claim 4.

Images