JP5799550B2 - Imaging apparatus, imaging method, and imaging program - Google Patents

Description

  The present invention relates to an imaging apparatus, an imaging method, and an imaging program. More specifically, the present invention relates to an imaging apparatus, an imaging method, and an imaging program suitable for white balance correction.

  In an imaging device using a CCD (Charge Coupled Device) image sensor or the like as an imaging device, the color change of the output signal of the CCD due to the color temperature of the light source is corrected so as not to feel unnatural to the human eye. White balance correction is one of the essential functions.

  As a technique related to such white balance correction, for example, Patent Document 1 discloses that white balance correction is performed accurately even if the S / N deteriorates due to the saturation of the output of the image sensor or the influence of noise components included in the image signal. For the purpose of performing the above, a video signal processing device is disclosed in which a threshold is set for a luminance signal and white balance correction is performed based on a signal exceeding the threshold.

  In Patent Document 2, a threshold is set for each color component of an image signal for the purpose of improving the accuracy of white balance correction when a subject has an image region of a high luminance portion or a low luminance portion, and a high luminance portion ( An imaging processing apparatus that performs white balance correction by removing a signal that becomes a whiteout region) or a low luminance portion (blackout region) is disclosed.

  However, in the technique described in the above-mentioned patent document, when AE (Auto Exposure) is performed based on RGB excluding low luminance and high luminance in pixel units, information on original brightness can be obtained. In addition, since proper exposure cannot be performed, an RGB acquisition circuit for performing AE is required in addition to the white balance control, which causes a problem that the cost increases due to an increase in circuit scale.

  In addition, when the RGB or luminance value threshold setting is the same regardless of the shooting conditions, the accuracy of white balance correction is reduced by using, for example, an image signal in a low luminance area where the S / N has deteriorated in high sensitivity shooting. Problem arises.

  Therefore, the present invention divides the image area corresponding to the image sensor into a predetermined number of blocks, and removes blocks that may cause noise from calculation targets in white balance control under predetermined conditions, thereby preventing color misregistration. An object of the present invention is to provide an imaging apparatus, an imaging method, and an imaging program capable of performing good white balance correction.

In order to achieve such an object, an imaging apparatus according to the present invention divides light incident from an optical system into an electrical signal and outputs it as an imaging signal, and an image area corresponding to the imaging element is divided into a plurality of blocks. An R, G, and B integrated values for R, G, and B values based on the imaging signal for each block, and R, G, and B integrated values, respectively, An upper limit value and a lower limit value are set for each of the integrated value, the G integrated value, and the B integrated value. The lower limit value of the R integrated value and the B integrated value is less than the lower limit value of the G integrated value. Effective block determining means for determining a block that falls within the effective block, and white balance correction coefficient calculating means for calculating a white balance correction coefficient based on the R integrated value, G integrated value, and B integrated value of the effective block And white balance control based on the white balance correction coefficient.

An imaging method according to the present invention is an imaging method in an imaging apparatus including an imaging device that converts light incident from an optical system into an electrical signal and outputs the electrical signal, and an image region corresponding to the imaging device is obtained. RGB for calculating the R integrated value, G integrated value, and B integrated value, which are the integrated values for the R value, G value, and B value based on the imaging signal for each block An upper limit value and a lower limit value are set for the integration process, the R integration value, the G integration value, and the B integration value, respectively. The lower limit value of the R integration value and the B integration value is less than the lower limit value of the G integration value, An effective block determination process for determining a block that falls within the upper limit value and the lower limit value as an effective block, and a white balance that calculates a white balance correction coefficient based on the R integrated value, G integrated value, and B integrated value of the effective block And a white balance process based on the white balance correction coefficient.

In addition, an imaging program according to the present invention divides an image area corresponding to an imaging device into a plurality of blocks in an imaging device including an imaging device that converts light incident from an optical system into an electrical signal and outputs the electrical signal. Block division processing to be performed, RGB integration processing for calculating an R integrated value, a G integrated value, and a B integrated value as R integrated values for the R value, G value, and B value based on the imaging signal for each block; An upper limit value and a lower limit value are set for each of the integrated value, the G integrated value, and the B integrated value. The lower limit value of the R integrated value and the B integrated value is less than the lower limit value of the G integrated value. An effective block determination process that determines a block that falls within the effective block, and a white balance correction coefficient calculation process that calculates a white balance correction coefficient based on the R integrated value, G integrated value, and B integrated value of the effective block. And white balance processing based on the white balance correction coefficient.

  According to the present invention, good white balance correction without color misregistration can be performed.

BRIEF DESCRIPTION OF THE DRAWINGS It is an example of the external view of the digital camera which is one Embodiment of the imaging device which concerns on this invention, (a) is a top view, (b) is a front view, (c) shows a back view. It is an example of the functional block diagram of the imaging device which concerns on this embodiment. It is a schematic diagram of the control block of CPU which concerns on white balance control. It is a flowchart (1st Embodiment) of a white balance process. It is a flowchart (2nd Embodiment) of a white balance process. It is a graph which shows the example of a setting of (A) lower limit and (B) upper limit for effective block determination according to ISO sensitivity. 12 is a flowchart of a white balance process (third embodiment). It is a graph which shows the example of a setting of (A) lower limit and (B) upper limit for effective block determination according to an exposure correction coefficient.

  Hereinafter, the configuration according to the present invention will be described in detail based on the embodiment shown in FIGS.

  The image pickup apparatus (digital camera) according to the present embodiment converts an incident light from an optical system into an electric signal and outputs it as an image pickup signal (CCD 121), and an image area corresponding to the image pickup element into a plurality of blocks. Block dividing means (101) for dividing, and RGB integration for calculating R integrated value, G integrated value, and B integrated value which are respective integrated values for R value, G value, and B value based on the imaging signal for each block Means (102) and effective block determination means for setting an upper limit value and a lower limit value for the R integrated value, G integrated value, and B integrated value, respectively, and determining a block that falls within the upper limit value and the lower limit value as an effective block (103) and white balance correction coefficient calculating means (105) for calculating a white balance correction coefficient based on the R integrated value, G integrated value, and B integrated value of the effective block. , And it performs the white balance control on the basis of the white balance correction coefficient.

[First Embodiment]
(Configuration of imaging device)
In the present embodiment, a digital camera will be described as an example of an imaging apparatus. FIG. 1 shows an external view of a digital camera, (a) shows a top view of the camera, (b) shows a front view of the camera, and (c) shows a rear view of the camera. Note that the imaging apparatus is not limited to a digital camera, and may be any imaging apparatus having a white balance correction function.

  As shown in FIG. 1A, the digital camera has a sub LCD 1, a release shutter 2 (SW1), and a mode dial 4 (SW2) on the upper surface.

  As shown in FIG. 1B, the digital camera has a strobe light emitting unit 3, a distance measuring unit 5, a remote control light receiving unit 6, a lens unit 7, and an optical viewfinder (front) 11 on the front. Have. A memory card throttle 23 indicates a throttle for inserting a memory card 34 such as an SD card, and is provided on the side of the camera.

  As shown in FIG. 1C, the digital camera has an AFLED (autofocus LED) 8, a strobe LED 9, an LCD monitor (display means) 10, an optical viewfinder (back surface) 11, and a zoom on the back surface. It has a button (zoom lever) TELE12 (SW4), a power switch 13 (SW13), a zoom button (zoom lever) WIDE14 (SW3), and a self-timer / deletion switch 15 (SW6).

  Furthermore, the menu switch 16 (SW5), the OK switch 17 (SW12), the left / image confirmation switch 18 (SW11), the down / macro switch 19 (SW10), the up / strobe switch 20 (SW7), the right A switch 21 (SW8) and a display switch 22 (SW9) for displaying an image are provided.

  FIG. 2 is a functional block diagram of a control system of the digital camera shown in FIG. The system configuration inside the digital camera will be described below.

  As shown in FIG. 2, in this digital camera, a CCD 121 serving as a solid-state imaging device, on which a subject image incident through a photographing lens system installed in the lens unit 7 forms an image on a light receiving surface, is output from the CCD 121. Front-end IC (F / E) 120 that processes signals (analog RGB image signals) into digital signals, signal-processing IC 110 that processes digital signals output from front-end IC (F / E) 120, and data temporarily An SDRAM 33 to be stored, a ROM 30 in which a control program and the like are stored, a motor driver 32 and the like are provided.

  The lens unit 7 includes a zoom lens, a focus lens, a mechanical shutter, and the like, and is driven by a motor driver 32. The motor driver 32 is controlled by a microcomputer (CPU, control unit) 111 included in the signal processing IC 110.

  The CCD 121 is a solid-state imaging device for photoelectrically converting an optical image, and an RGB primary color filter as a color separation filter is arranged on a plurality of pixels constituting the CCD, and an electrical signal (analogue) corresponding to RGB three primary colors. RGB image signal) is output.

  A front-end IC (F / E) 120 is a CDS 122 that performs sampling hold (correlated double sampling) on the CCD output electrical signal (analog image data), and an AGC (Auto Gain Control) 123 that adjusts the gain of the sampled data. A vertical synchronization signal (VD) and a horizontal synchronization signal (HD) are supplied from an A / D converter (A / D) 124 that performs digital signal conversion and a CCD I / F 112, and drive timing signals for the CCD 121 and the F / E 120 are supplied. A TG (timing generator: control signal generator) 125 is generated.

  The oscillator (clock generator) supplies a clock to the system clock of the signal processing IC 110 including the CPU 111, the TG 125, and the like. The TG 125 receives the oscillator clock and supplies a pixel clock for pixel synchronization to the CCD I / F 112 in the signal processing IC 110.

  A digital signal input from the F / E 120 to the signal processing IC 110 is temporarily stored as RGB data (RAW-RGB) in the SDRAM 33 by the memory controller 115 via the CCD I / F 112.

  The signal processing IC 110 includes a CPU 111 that performs system control, a CCD I / F 112, a resizing processing unit 113, a memory controller 115, a display output control unit 116, a compression / expansion unit 117, a media I / F unit 118, a YUV conversion unit 119, and the like. ing.

  The CCD I / F 112 outputs a vertical synchronizing signal (VD) and a horizontal synchronizing signal (HD), takes in a digital (RGB) signal input from the A / D 124 in accordance with the synchronizing signal, and passes through the memory controller 115. RGB data is written to the SDRAM 33.

  The display output control unit 116 sends the display data written in the SDRAM 33 to the display unit, and displays the captured image. The display output control unit 116 can display on the LCD monitor 10 built in the digital camera, or output it as a TV video signal and display it on an external device.

  The display data here is OSD (on-screen display) data for displaying a natural image YCbCr, a shooting mode icon, etc., and the memory controller 115 reads and displays the data placed on the SDRAM 33. The data is sent to the output control unit 116, and the data synthesized by the display output control unit 116 is output as video data.

  The compression / decompression unit 117 compresses the YCbCr data written in the SDRAM 33 during recording and outputs JPEG-encoded data. During reproduction, the compression / decompression unit 117 decompresses the read JPEG-encoded data into YCbCr data and outputs the YCbCr data.

  The media I / F 118 reads data in the memory card 34 to the SDRAM 33 or writes data on the SDRAM 33 to the memory card 34 in accordance with an instruction from the CPU 111.

  The YUV conversion unit 119 converts the RGB data temporarily stored in the SDRAM 33 into luminance Y and color difference CbCr data (YUV data) based on the image development processing parameters set by the CPU 111, and writes back to the SDRAM 33.

  The resizing processing unit 113 reads out YUV data and performs size conversion to a size necessary for recording, size conversion to a thumbnail image, size conversion to a size suitable for display, and the like.

  In addition, the CPU 111 which is a control unit that controls the overall operation loads a control program and control data for controlling the camera stored in the ROM 30 at the time of startup into, for example, the SDRAM 33, and performs the overall operation based on the program code. Control.

  The CPU 111 performs imaging operation control, setting of image development processing parameters, in accordance with an instruction by a button key of the operation unit 31, an external operation instruction from a remote controller (not shown), or a communication operation instruction by communication from an external terminal such as a personal computer. Performs memory control and display control.

  The operation unit 31 is used by the photographer to instruct the operation of the digital camera, and a predetermined operation instruction signal is input to the control unit by the operation of the photographer. For example, as shown in FIG. 1, various button keys such as a two-stage (half-pressed and fully-pressed) release shutter 2 for instructing shooting, zoom buttons 12 and 14 for setting an optical zoom and an electronic zoom magnification are provided.

  When the operation unit 31 detects that the power key of the digital camera is turned on, the CPU 111 performs a predetermined setting for each block. With this setting, an image received by the CCD 121 via the lens unit 7 is converted into a digital video signal and input to the signal processing IC 110.

  The digital signal input to the signal processing IC 110 is input to the CCD I / F 112. The CCD I / F 112 performs processing such as black level adjustment on the photoelectrically converted analog signal and temporarily stores it in the SDRAM 33. The RAW-RGB image data stored in the SDRAM 33 is read by the YUV conversion unit 119, and subjected to gamma conversion processing, white balance processing, edge enhancement processing, and YUV conversion processing, and is written back to the SDRAM 33 as YUV image data. .

  The YUV image data is read by the display output control unit 116. For example, if the output destination is an NTSC system TV, the resizing processing unit 113 performs horizontal / vertical scaling processing according to the system, and Is output. By performing this process for each VD, monitoring which is a display for confirmation before still photographing is performed.

(Operation of imaging device)
Next, the monitoring operation and still image shooting operation of the digital camera will be described. This digital camera performs a still image shooting operation while performing a monitoring operation as described below in the still image shooting mode.

  First, when the photographer turns on the power switch 13 and sets the mode dial 4 to the photographing mode (still image photographing mode), the digital camera is activated in the recording mode. When the CPU 111 detects this, the CPU 111 outputs a control signal to the motor driver 32 to move the lens unit 7 to a photographing position, and the CCD 121, F / E 120, signal processing IC 110, SDRAM 33, ROM 30, LCD monitor 10 And so on.

  Then, by directing the photographic lens system of the lens unit 7 toward the subject, a subject image incident through the photographic lens system is formed on the light receiving surface of each pixel of the CCD 121. An electrical signal (analog RGB image signal) corresponding to the subject image output from the CCD 121 is input to the A / D 124 via the CDS 122 and AGC 123, and converted into 12-bit RAW-RGB data by the A / D 124.

  This RAW-RGB data is taken into the CCD I / F 112 of the signal processing IC 110 and stored in the SDRAM 33 via the memory controller 115. The RAW-RGB data read from the SDRAM 33 is input to the YUV conversion unit 119 and converted into YUV data that can be displayed, and then the YUV data is stored in the SDRAM 33 via the memory controller 115. .

  The YUV data read from the SDRAM 33 via the memory controller 115 is sent to the LCD monitor 10 via the display output control unit 116, and a captured image (moving image) is displayed. At the time of monitoring in which a photographed image is displayed on the LCD monitor 10, one frame is read out in a time of 1/30 seconds by thinning out the number of pixels by the CCD I / F 112.

  In this monitoring operation, the photographed image (moving image) is only displayed on the LCD monitor 10 functioning as an electronic viewfinder, and the release button 2 is not yet pressed (including half-pressed).

  By displaying the photographed image on the LCD monitor 10, the composition for photographing a still image can be confirmed. In addition, it can output as a TV video signal from the display output control part 116, and can display a picked-up image (moving image) on external TV (television) via a video cable.

  Then, the CCD I / F 112 of the signal processing IC 110 calculates an AF (automatic focus) evaluation value, an AE (automatic exposure) evaluation value, an AWB (auto white balance) evaluation value (WB evaluation value) from the captured RAW-RGB data. Say).

  The AF evaluation value is calculated by, for example, the output integrated value of the high frequency component extraction filter or the integrated value of the luminance difference between adjacent pixels. When in the in-focus state, the edge portion of the subject is clear, so the high frequency component is the highest. By using this, at the time of AF operation (focus detection operation), AF evaluation values at each focus lens position in the photographing lens system are acquired, and AF operation is performed with the maximum point as the focus detection position. Is executed.

  The AE evaluation value and the AWB evaluation value are calculated from the integrated values of the RGB values in the RAW-RGB data. For example, the screen (image area) corresponding to the light receiving surface of all the pixels of the CCD 121 is equally divided into 256 blocks (areas) (horizontal 16 divisions and vertical 16 divisions), and the RGB integration of each block is calculated.

  Then, the control unit reads the calculated RGB integrated value, and in the AE process, calculates the luminance of each area (block) of the screen and determines an appropriate exposure amount from the luminance distribution. Based on the determined exposure amount, exposure conditions (the number of electronic shutters of the CCD 121, the aperture value of the aperture unit, the insertion and removal of the ND filter, etc.) are set. In the AWB process, an AWB control value that matches the color of the light source of the subject is determined from the RGB distribution. By this AWB process, white balance is adjusted when the YUV conversion unit 119 performs conversion processing to YUV data. Note that the AE process and the AWB process are continuously performed during monitoring.

  Then, when a still image shooting operation in which the release button is pressed (half-pressed to fully pressed) is started during the monitoring operation, an AF operation that is a focus position detection operation and a still image recording process are performed.

  That is, when the release button is pressed (half to full), the focus lens of the photographing lens system is moved by a drive command from the control unit to the motor driver 32. For example, contrast evaluation called so-called hill-climbing AF is performed. The AF operation of the method is executed.

  When the AF (focusing) target range is the entire region from infinity to close, the focus lens of the taking lens system moves to each focus position from close to infinity or from infinity to close, and the CCD I / F 112 The control unit reads the AF evaluation value at each focus position calculated in step (1). Then, the focus lens is moved to the in-focus position with the point where the AF evaluation value at each focus position is maximized as the in-focus position, and in-focus.

  Then, AE processing is performed, and when the exposure is completed, the mechanical shutter unit is closed by a drive command from the control unit to the motor driver 32, and an analog RGB image signal for a still image is output from the CCD 121. Then, as in the monitoring, the data is converted into RAW-RGB data by the A / D 124 of the F / E 120.

  The RAW-RGB data is taken into the CCD I / F 112 of the signal processing IC 110, converted into YUV data by the YUV conversion unit 119, and stored in the SDRAM 33 via the memory controller 115. The YUV data is read from the SDRAM 33, converted into a size corresponding to the number of recording pixels by the resizing processing unit 113, and compressed to image data in the JPEG format or the like by the compression / decompression unit 117. The compressed image data such as JPEG format is written back to the SDRAM 33, read from the SDRAM 33 via the memory controller 115, and stored in the memory card 34 via the media I / F 118.

(White balance control)
FIG. 3 is an explanatory diagram of a control block of the CPU 111 related to white balance control. White balance control (an imaging method according to the present invention) executed by each control block of the CPU 111 will be described with reference to a processing flowchart shown in FIG. Note that each of the block dividing unit 101, the RGB integrating unit 102, the effective block determining unit 103, the white detecting unit 104, and the white balance coefficient calculating unit 105 causes the imaging apparatus to execute software (imaging program) executed by the CPU 111. The data necessary for the execution is loaded into the SDRAM 33, for example.

  First, as described above, the RGB integrating means 102 corresponds to the image area (the light receiving surface of all the pixels of the CCD 121) that is divided into 256 blocks by the block dividing means 101 after RAW-RGB is taken into the CCD I / F 112. Screen) for each block, R values, G values, and B values (also simply referred to as R, G, and B, collectively referred to as RGB), integrated values (R integrated values, G integrated values, and B integrated values). (S101: RGB integrated value acquisition process). The R value, the G value, and the B value are expressed by, for example, 8 bits, but the quantification method is not particularly limited.

Next, an average value of RGB per pixel (also referred to as an R average value, a G average value, or a B average value, collectively referred to as an RGB average value) is calculated from the obtained RGB integrated values of each block, and a WB evaluation value (G / R, G / B) and AE evaluation value (Y) are calculated (S102: WB evaluation value, AE evaluation value generation process). Here, the calculation of the WB evaluation value (G / R, G / B) and the AE evaluation value (Y) can be calculated by, for example, the following equations (1) to (3).
G / R = (G average value × 100) / R average value (1)
G / B = (G average value × 100) / B average value (2)
Y = (R average value × 3 + G average value × 6 + B average value) / 10 (3)
Note that the calculation method of the WB evaluation value (G / R, G / B) and the AE evaluation value (Y) is not limited to the above example, but may be other known or new calculation methods. good.

  Next, the effective block determination unit 103 determines whether all of the RGB integrated values of each of the divided blocks are within a predetermined upper limit (upper limit threshold) and lower limit (lower limit threshold) range, A block that falls within the range is determined as a valid block (S103: valid block determination process).

  By performing this effective block determination process, if any of RGB is blacked out or saturated in the subject's color deviation or low-luminance part, the calculation is performed as an invalid block in white balance control. You can avoid it.

  Further, in setting the upper limit value and the lower limit value in the effective block determination process, considering that the R and B sensitivities are relatively lower than the G sensitivity as the spectral characteristics of the image sensor, the R integrated value and the B integrated value are set. It is preferable to lower the lower limit for the G integrated value. Thereby, the RGB integrated value with low reliability can be excluded from the calculation target in the white balance control.

  Next, when the WB evaluation value (G / R, G / B) for the effective block is within the preset white extraction range, it is stored as a white extraction block (S104: white detection process).

  Next, white balance correction coefficient calculation processing (S105) is performed. In the white balance correction coefficient calculation process, first, it is determined whether or not the number of white extraction blocks extracted by the white extraction process is equal to or greater than a predetermined number. If the number is equal to or greater than the predetermined number, the WB evaluation value (G / R, G) of each white extraction block is determined. / B) is weighted with the AE evaluation value (Y) of the corresponding block, and then integrated to calculate G / R and G / B per pixel.

  On the other hand, when there is no white extraction block number exceeding a certain standard, WB evaluation values (G / R, G / B) of all blocks are integrated to calculate G / R, G / B per pixel. .

  The average of G / R and G / B per pixel obtained in this way is defined as WB correction coefficients Rgain and Bgain.

  Corrections are made for each area on the calculated color coordinates of G / R and G / B to G / R and G / B per pixel, and G / R and G / B are used as WB correction coefficients. Note that correction for each area means, for example, that G / R is increased and G / B is decreased so that the light source color is left in a scene on the low color temperature side where the value of G / R is small and G / B is large. In a scene on the high color temperature side where the value of / R is large and G / B is small, limit processing is performed if G / R is a certain value or more.

  Finally, white balance correction is performed by multiplying R and B pixels of the entire screen by WB correction coefficients Rgain and Bgain, respectively.

  The correction coefficient calculation method in the white balance correction coefficient calculation process is not limited to the above example, and other known or new calculation methods may be applied to the effective block.

  As described above, according to the imaging apparatus according to the present embodiment, it is possible to perform good white balance control without color misregistration regardless of the sensitivity of the image sensor. Also, since it is possible to perform both automatic exposure control and white balance control by a single RGB integration process, the accuracy of white balance control can be improved at a low cost without increasing the circuit scale. .

[Second Embodiment]
Hereinafter, other embodiments of the imaging apparatus according to the present embodiment will be described. Note that the description of the same points as in the first embodiment will be omitted as appropriate.

  When white balance correction is performed with the same RGB or luminance value threshold setting regardless of the shooting conditions, for example, white balance can be obtained by using an image signal in a low luminance area where the S / N has deteriorated in high sensitivity shooting. There has been a problem that the accuracy of correction is reduced.

  Therefore, in the first embodiment, the upper and lower limit values in the effective block determination process are fixed regardless of the shooting conditions. In the second embodiment, the upper and lower limit values are set according to the ISO sensitivity. It is. 6 shows a processing flowchart shown in FIG.

  First, the RGB integrated value acquisition process (S201) and the WB evaluation value / AE evaluation value generation process (S202) are the RGB integrated value acquisition process (S101), the WB evaluation value, and the AE evaluation value generation process (S202) of the first embodiment. Similar to S102).

  Next, as shown in FIG. 6A, a lower limit value for determining an effective block is set according to the ISO sensitivity (S203: RGB threshold value setting process according to the ISO sensitivity). In the example shown in FIG. 6 (A), the lower limit is increased as the ISO sensitivity increases in order to eliminate blocks with poor S / N. Further, as shown in FIG. 6B, the upper limit value may be lowered as the ISO sensitivity increases.

  The determination of the effective block according to the ISO sensitivity is performed only for one of the lower limit value and the upper limit value, and the other value may be a predetermined value as in the first embodiment, or the lower limit value and the upper limit value may be determined. For both, the value may be changed according to the ISO sensitivity.

  As described above, based on the set upper limit value and lower limit value, the effective block determination unit 103 determines whether the RGB integrated values of each divided block are within the set lower limit value and upper limit value range, respectively. Whether or not the block is within the range is determined as a valid block (S204: valid block determination process).

  Hereinafter, the white detection process (S205) and the white balance correction coefficient calculation process (S206) are performed in the same manner as the white detection process (S104) and the white balance correction coefficient calculation process (S105) of the first embodiment.

  As described above, according to the imaging apparatus according to the present embodiment, it is possible to perform good white balance control without color misregistration regardless of the sensitivity of the image sensor. Also, since it is possible to perform both automatic exposure control and white balance control by a single RGB integration process, the accuracy of white balance control can be improved at a low cost without increasing the circuit scale. . Further, stable and highly accurate white balance control can be performed even when the ISO sensitivity is high.

[Third Embodiment]
In the first embodiment, the upper and lower limit values in the effective block determination process are fixed regardless of the shooting conditions. However, in the third embodiment, an exposure correction value (exposure correction coefficient) set by a user operation is used. The upper and lower limit values are set according to the above. FIG. 8 shows a processing flowchart shown in FIG. 7. FIG.

  First, the RGB integrated value acquisition process (S301) and the WB evaluation value / AE evaluation value generation process (S302) are the RGB integrated value acquisition process (S101), the WB evaluation value, and the AE evaluation value generation process (S302) of the first embodiment. Similar to S102).

  Next, as shown in FIG. 8A, a lower limit value for determining an effective block is set according to the exposure correction coefficient (S303: RGB threshold value setting process according to exposure correction). In FIG. 8A, the lower limit value is increased when the exposure correction coefficient is increased (corrected brightly), and the lower limit value is decreased when the exposure correction coefficient is decreased (corrected darker). Further, the upper limit value may be shifted as shown in FIG.

  The determination of the effective block in accordance with the exposure correction is performed only on one of the lower limit value and the upper limit value, and the other value may be a predetermined value as in the first embodiment, or the lower limit value and the upper limit value. For both, the value may be changed according to the exposure correction.

  As described above, based on the set upper limit value and lower limit value, the effective block determination unit 103 determines whether the RGB integrated values of each divided block are within the set lower limit value and upper limit value range, respectively. Whether or not the block is within the range is determined as a valid block (S304: valid block determination process).

  Hereinafter, the white detection process (S305) and the white balance correction coefficient calculation process (S306) are performed in the same manner as the white detection process (S104) and the white balance correction coefficient calculation process (S105) of the first embodiment.

  As described above, according to the imaging apparatus according to the present embodiment, it is possible to perform good white balance control without color misregistration regardless of the sensitivity of the image sensor. Also, since it is possible to perform both automatic exposure control and white balance control by a single RGB integration process, the accuracy of white balance control can be improved at a low cost without increasing the circuit scale. . Further, stable and accurate white balance control can be performed regardless of the set exposure correction value.

  The white balance control by the imaging apparatus described above can also be executed by a program (imaging program). The present invention is also applied to a recording medium in which the imaging program is recorded so as to be executable by the imaging apparatus.

  The above-described embodiment is a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the gist of the present invention.

1 Sub LCD
2 Release shutter (SW1)
3 Flash unit 4 Mode dial (SW2)
5 Distance measuring unit 6 Remote control light receiving unit 7 Lens unit 8 AFLED
9 Strobe LED
10 LCD Monitor 11 Optical Finder 12 Zoom Button TELE (SW4)
13 Power switch (SW13)
14 Zoom button WIDE (SW3)
15 Self-timer / deletion switch (SW5)
16 Menu switch (SW6)
17 OK switch (SW12)
18 Left / image confirmation switch (SW11)
19 Lower / Macro switch (SW10)
20 Up / Strobe switch (SW7)
21 Right switch (SW8)
22 Display switch (SW9)
23 Memory card throttle 30 ROM
31 Operation unit 32 Motor driver 33 SDRAM
34 Memory card 101 Block dividing means 102 RGB integrating means 103 Effective block determining means 104 White detecting means 105 White balance coefficient calculating means 110 Signal processing IC
111 CPU
112 CCD I / F
113 Resize processing unit 115 Memory controller 116 Display output control unit 117 Compression / decompression unit 118 Media I / F
119 YUV converter 120 F / E
121 CCD
122 CDS
123 AGC
124 A / D converter 125 Timing generator

Japanese Patent Laid-Open No. 2002-290987 JP 2005-109705 A

Claims (6)

An image sensor that converts light incident from the optical system into an electrical signal and outputs the signal as an image signal;
Block dividing means for dividing an image region corresponding to the image sensor into a plurality of blocks;
RGB integration means for calculating an R integrated value, a G integrated value, and a B integrated value, which are integrated values for the R value, G value, and B value based on the imaging signal, for each block;
An upper limit value and a lower limit value are respectively set for the R integrated value, the G integrated value, and the B integrated value, and the lower limit values of the R integrated value and the B integrated value are less than the lower limit value of the G integrated value, Effective block determining means for determining a block that falls within the upper limit value and the lower limit value as an effective block;
White balance correction coefficient calculation means for calculating a white balance correction coefficient based on the R integrated value, G integrated value, and B integrated value of the effective block;
An image pickup apparatus that performs white balance control based on the white balance correction coefficient.   2. The imaging apparatus according to claim 1, wherein automatic exposure control is performed based on the R integrated value, G integrated value, and B integrated value calculated by the RGB integrating means.   The effective block determination means sets the upper limit value and / or the lower limit value for the R integrated value, the G integrated value, and the B integrated value according to ISO sensitivity. Imaging device.   2. The effective block determination means sets the upper limit value and / or the lower limit value for the R integrated value, G integrated value, and B integrated value according to a set exposure correction coefficient. Or the imaging device of 2. An imaging method in an imaging apparatus including an imaging element that converts light incident from an optical system into an electrical signal and outputs the electrical signal,
Block division processing for dividing an image region corresponding to the image sensor into a plurality of blocks;
RGB integration processing for calculating an R integrated value, a G integrated value, and a B integrated value, which are the integrated values of the R value, the G value, and the B value based on the imaging signal for each block;
An upper limit value and a lower limit value are respectively set for the R integrated value, the G integrated value, and the B integrated value, and the lower limit values of the R integrated value and the B integrated value are less than the lower limit value of the G integrated value, An effective block determination process for determining a block that falls within the upper limit value and the lower limit value as an effective block;
A white balance correction coefficient calculation process for calculating a white balance correction coefficient based on the R integrated value, G integrated value, and B integrated value of the effective block;
An imaging method comprising: performing white balance processing based on the white balance correction coefficient. In an imaging device provided with an imaging device that converts light incident from an optical system into an electrical signal and outputs it as an imaging signal,
Block division processing for dividing an image region corresponding to the image sensor into a plurality of blocks;
RGB integration processing for calculating an R integrated value, a G integrated value, and a B integrated value, which are the integrated values of the R value, the G value, and the B value based on the imaging signal for each block;
An upper limit value and a lower limit value are respectively set for the R integrated value, the G integrated value, and the B integrated value, and the lower limit values of the R integrated value and the B integrated value are less than the lower limit value of the G integrated value, An effective block determination process for determining a block that falls within the upper limit value and the lower limit value as an effective block;
A white balance correction coefficient calculation process for calculating a white balance correction coefficient based on the R integrated value, G integrated value, and B integrated value of the effective block;
An imaging program that executes white balance processing based on the white balance correction coefficient.

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