JP2013048319A - Imaging apparatus, imaging method and imaging program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve sufficient white balance correction even in the middle of a zoom operation.SOLUTION: An imaging apparatus includes: white balance evaluation value acquiring means 103 for acquiring an evaluation value used for white balance control from an imaging signal; first white balance correction coefficient calculating means 105 for calculating a first white balance correction coefficient on the basis of the evaluation value; zoom magnification change means 106 for changing zoom magnification of an optical system; storage means for storing a white balance correction coefficient used for the white balance control; white balance following means 107 for setting white balance following speed in accordance with the change of the zoom magnification; and second white balance correction coefficient calculating means 108 for calculating a second white balance correction coefficient on the basis of the white balance correction coefficient stored in the storage means, and the first white balance correction coefficient and the white balance following speed. While the zoom magnification is changed, the second white balance correction coefficient is set to be the white balance correction coefficient.

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.

  In white balance correction, for example, shooting conditions (that is, light sources) such as outdoors (clear weather), cloudy weather (shade), incandescent lamps, fluorescent lamps, etc. are determined, and an optimal white balance gain according to the shooting conditions is determined. A technique for executing white balance correction is known.

  On the other hand, it is known that white balance correction cannot be performed correctly when an image of a subject becomes small due to a zoom operation (zoom magnification changing operation) of the imaging apparatus. To deal with this problem, for example, in Patent Document 1, based on the image data generated before the zoom magnification change based on the information on the screen center portion and the information on the screen periphery portion of the image data before the zoom magnification change. An imaging apparatus that selectively controls whether to perform white balance correction or to perform white balance correction based on image data generated after changing the zoom magnification is disclosed.

  However, in the technique described in the above-mentioned patent document, for example, when the light source changes during the zoom operation, if the subject information before the light source change is used, the white balance malfunctions, resulting in an inappropriate white balance. There was a problem that correction was performed.

  SUMMARY An advantage of some aspects of the invention is that it provides an imaging apparatus, an imaging method, and an imaging program capable of performing good white balance correction even during a zoom operation.

  In order to achieve this object, an imaging apparatus according to the present invention acquires an evaluation value used for white balance control from an imaging element that converts light incident from an optical system into an electrical signal and outputs the electrical signal as an imaging signal. White balance evaluation value acquisition means, first white balance correction coefficient calculation means for calculating a first white balance correction coefficient based on the evaluation value acquired by the white balance evaluation value acquisition means, and zoom for changing the zoom magnification of the optical system Magnification changing means, storage means for storing a white balance correction coefficient used for white balance control, white balance tracking means for setting a white balance tracking speed in accordance with a change in zoom magnification, and storage means. White balance correction coefficient, first white balance correction coefficient and white bar Second white balance correction coefficient calculating means for calculating a second white balance correction coefficient based on the tracking speed, and during the zoom magnification change by the zoom magnification changing means, the second white balance correction coefficient is white balance controlled. The white balance correction coefficient used in

  In addition, an imaging device according to the present invention includes an imaging element that converts light incident from an optical system into an electrical signal and outputs the electrical signal, and obtains an evaluation value used for white balance control from the imaging signal. Means, a first white balance correction coefficient calculating means for calculating a first white balance correction coefficient based on the evaluation value acquired by the white balance evaluation value acquiring means, a zoom magnification changing means for changing the zoom magnification of the optical system, One of the storage means for storing the white balance correction coefficient used for white balance control, the white balance correction coefficient stored in the storage means, and the first white balance correction coefficient is used as the second white balance correction coefficient. Second white balance correction coefficient calculating means, and by means of zoom magnification changing means When the zoom magnification is enlarged, the white balance correction coefficient stored in the storage means is used as the second white balance correction coefficient. When the zoom magnification is reduced by the zoom magnification changing means, the first white balance correction coefficient is changed to the first white balance correction coefficient. Two white balance correction coefficients are used, and white balance control is performed using the second white balance correction coefficient.

  The 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 is used for white balance control from the imaging signal. White balance evaluation value acquisition processing for acquiring an evaluation value, first white balance correction coefficient calculation processing for calculating a first white balance correction coefficient based on the evaluation value acquired by the white balance evaluation value acquisition processing, and zooming of the optical system Zoom magnification change processing for changing the magnification, storage processing for storing the white balance correction coefficient used for white balance control, white balance tracking processing for setting the white balance tracking speed in accordance with the change of the zoom magnification, and storage White balance correction coefficient stored by processing, first white balance correction factor And the second white balance correction coefficient calculation process for calculating the second white balance correction coefficient based on the white balance follow-up speed, and the white balance control using the second white balance correction coefficient during the zoom magnification change by the zoom magnification change process. The white balance correction process is performed.

  The imaging program according to the present invention acquires an evaluation value used for white balance control from an imaging signal 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. A white balance evaluation value acquisition process, a first white balance correction coefficient calculation process for calculating a first white balance correction coefficient based on the evaluation value acquired by the white balance evaluation value acquisition process, and a zoom for changing the zoom magnification of the optical system Stored by the magnification change processing, the storage processing for storing the white balance correction coefficient used for white balance control, the white balance tracking processing for setting the white balance tracking speed according to the change of the zoom magnification, and the storage processing. White balance correction coefficient, first white balance correction coefficient, and white During the second white balance correction coefficient calculation process for calculating the second white balance correction coefficient based on the lance tracking speed and the zoom magnification change by the zoom magnification change process, the white balance control is performed using the second white balance correction coefficient. White balance correction processing.

  According to the present invention, it is possible to perform good white balance correction even during a zoom operation.

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 explanatory drawing of the white block extraction in the two-dimensional color coordinate which makes G / R x-axis and G / B is y-axis. It is a graph which shows the change of the 2nd white balance correction coefficient in zoom operation to the expansion direction. It is a graph which shows the change of the 2nd white balance correction coefficient during zoom operation to a reduction direction. It is a flowchart (2nd Embodiment) of a white balance process.

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

[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 (storage means) 33 for storing, a ROM (storage means) 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 a picked-up image (moving image) can also be displayed on external TV (television) via a video cable.

  Then, the CCD I / F 112 of the signal processing IC 110 determines 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. (Also referred to as AWB evaluation value).

  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 WB 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 during zoom magnification change executed by each control block of the CPU 111 will be described with reference to a processing flowchart shown in FIG. The block dividing unit 101, the RGB integrating unit 102, the white balance evaluation value acquiring unit 103, the white extracting unit 104, the first white balance correction coefficient calculating unit 105, the zoom magnification changing unit 106, the white balance following unit 107, and the second white Each unit of the balance correction coefficient calculation unit 108 and the white balance correction unit 109 can be configured by causing the imaging apparatus to execute software (imaging program) executed by the CPU 111. Data necessary for the execution is, for example, It is loaded into the SDRAM 33. The zoom magnification changing unit 106 controls the optical system of the imaging apparatus to execute a zoom magnification changing operation. The storage device stores a white balance correction coefficient (current white balance correction coefficient) that has been used for white balance control up to the previous time, and is appropriately replaced below.

  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, the white balance evaluation value acquisition unit 103 obtains an average value of RGB for each pixel (also referred to as an R average value, a G average value, or a B average value from the acquired RGB integrated values of each block, and is collectively referred to as an RGB average value. Is calculated), and the WB evaluation value (G / R, G / B) and the 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, based on the WB evaluation values (G / R, G / B), the white extraction unit 104 stores a white extraction block (white block) within a preset white extraction range (S103: White extraction process). The specific processing method of the white extraction processing is not particularly limited, and a known or new white block extraction method may be used. For example, as shown in FIG. White detection is performed on a plurality of ellipse or rectangular frames along a blackbody radiation characteristic curve (blackbody radiation curve) (indicated by symbol c in FIG. 5) on two-dimensional color coordinates with G / B as the y-axis. It may be set as a frame, and when the WB evaluation value is included in the white detection frame, it may be detected as a white extraction block. In the example of FIG. 5, a plurality of ellipse frames are used as the white detection frames, and each ellipse frame is a white detection frame corresponding to the white detection range of each light source.

  Next, the first white balance correction coefficient calculating unit 105 determines whether or not the number of white extraction blocks extracted in the white extraction process (S103) is equal to or greater than a predetermined number. , The WB evaluation values (G / R, G / B) of each white extraction block are weighted by the average luminance (Y) of the corresponding block and then integrated to obtain G / R, G / B per pixel. Is calculated.

  On the other hand, when there are no more than a certain number of white extraction blocks, the WB evaluation values (G / R, G / B) of all the blocks are integrated to calculate G / R, G / B per pixel. The average values of the obtained G / R and G / B per pixel are set as first white balance correction coefficients Rgain1 and Bgain1 (S104: first white balance correction coefficient calculation process). The first white balance correction coefficients Rgain1 and Bgain1 are stored in the storage means for subsequent processing.

  Next, the white balance follow-up means 107 sets a white balance follow-up speed based on the enlargement / reduction of the zoom magnification changed by the zoom magnification changing means 106 controlling the optical system (S105: white balance follow-up speed). Setting process). The white balance tracking speed will be described below.

  Next, the second white balance correction coefficient calculation means 108 calculates the second white balance correction coefficients Rgain2 and Bgain2 using the following equations (4) and (5) (S106: second white balance correction coefficient calculation processing). . Also, the second white balance correction coefficients Rgain2 and Bgain2 are stored in the storage means for subsequent processing.

Rgain2 = {Rgain1 × AWBspeed + RgainNow × (100−AWBspeed)} / 100 (4)
Bgain2 = {Bgain1 × AWBspeed + BgainNow × (100−AWBspeed)} / 100 (5)
here,
AWBspeed: white balance tracking speed Rgain1: first white balance correction coefficient (Rgain) calculated and stored in S104
Bgain1: First white balance correction coefficient (Bgain) calculated and stored in S104
RgainNow: White balance correction coefficient (Rgain) currently set, that is, Rgain2 calculated and stored in the previous main processing (S106)
BgainNow: White balance correction coefficient (Bgain) currently set, that is, Bgain2 calculated and stored in the previous main processing (S106)
It is.

  The white balance follow-up speed represents the speed at which RgainNow and BgainNow converge to Rgain1 and Bgain1. An example in which the white balance follow-up speed is set to 40 during zooming in the enlargement direction and 80 in the reduction direction will be described below.

  When the subject is constant, Rgain1 and Bgain1 are constant. FIG. 6 shows changes in Rgain2 and Bgain2 when the white balance tracking speed is 40 during zooming in the enlargement direction. FIG. 7 shows changes in Rgain2 and Bgain2 when the white balance follow-up speed is set to 80 during zooming in the reduction direction.

  Finally, the white balance correction means 109 performs white balance correction by multiplying the R and B pixels of the entire screen by the second white balance correction coefficients Rgain2 and Bgain2 (S107: white balance correction coefficient). Multiplication processing).

  According to the white balance processing described above, even if the light source changes during zoom enlargement, the white balance can be tracked. And good white balance can be achieved.

[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.

  White balance control during zoom magnification change according to the present embodiment will be described with reference to a processing flowchart shown in FIG. Note that the RGB integrated value acquisition process in S201, the WB evaluation value, the AE evaluation value generation process in S202, the white extraction process in S203, and the first white balance correction coefficient calculation process in S204 are the same as S101 to S104, respectively. Since it exists, description is abbreviate | omitted.

  In the present embodiment, the process corresponding to the white balance follow-up speed setting process (S105) is not performed, and the second white balance correction coefficient calculating unit 108 performs white balance before zooming (in the previous process) during zooming in the enlargement direction. The correction coefficients Rgain2 and Bgain2 are used, and the first white balance correction coefficients Rgain1 and Bgain1 are used as the white balance correction coefficients Rgain2 and Bgain2 during zooming in the reduction direction (S205: second white balance correction coefficient calculation process). Also, the second white balance correction coefficients Rgain2 and Bgain2 are stored in the storage means for subsequent processing.

  Finally, the white balance correction means 109 performs white balance correction by multiplying the R and B pixels of the entire screen by the second white balance correction coefficients Rgain2 and Bgain2 (S206: white balance correction coefficient). Multiplication processing).

  As described above, in the second embodiment, white balance tracking processing is performed only during zooming in the reduction direction in which more color information can be acquired even when zooming and zooming are repeated, and white balance tracking is performed during zooming in the zooming direction. By not performing good white balance correction, good white balance correction can be performed.

  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 (storage means)
31 Operation Unit 32 Motor Driver 33 SDRAM (Storage Unit)
34 Memory card 101 Block dividing means 102 RGB integrating means 103 White balance evaluation value acquiring means 104 White extracting means 105 First white balance correction coefficient calculating means 106 Zoom magnification changing means 107 White balance following means 108 Second white balance correction coefficient calculating means 109 White balance correction 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 c Black body radiation curve

JP 2010-050658 A

Claims (5)

An image sensor that converts light incident from the optical system into an electrical signal and outputs the signal as an image signal;
White balance evaluation value acquisition means for acquiring an evaluation value used for white balance control from the imaging signal;
First white balance correction coefficient calculation means for calculating a first white balance correction coefficient based on the evaluation value acquired by the white balance evaluation value acquisition means;
Zoom magnification changing means for changing the zoom magnification of the optical system;
Storage means for storing a white balance correction coefficient used for white balance control;
White balance tracking means for setting a white balance tracking speed according to the change of the zoom magnification;
Second white balance correction coefficient calculating means for calculating a second white balance correction coefficient based on the white balance correction coefficient, the first white balance correction coefficient, and the white balance tracking speed stored in the storage means; Have
The image pickup apparatus according to claim 1, wherein the second white balance correction coefficient is used as a white balance correction coefficient used for white balance control during the zoom magnification change by the zoom magnification changing means.   2. The imaging apparatus according to claim 1, wherein the white balance tracking unit sets the white balance tracking speed slower when the zoom magnification is increased by the zoom magnification changing unit than when the zoom magnification is reduced. . An image sensor that converts light incident from the optical system into an electrical signal and outputs the signal as an image signal;
White balance evaluation value acquisition means for acquiring an evaluation value used for white balance control from the imaging signal;
First white balance correction coefficient calculation means for calculating a first white balance correction coefficient based on the evaluation value acquired by the white balance evaluation value acquisition means;
Zoom magnification changing means for changing the zoom magnification of the optical system;
Storage means for storing a white balance correction coefficient used for white balance control;
A second white balance correction coefficient calculating means that uses either the white balance correction coefficient stored in the storage means or the first white balance correction coefficient as a second white balance correction coefficient;
When enlarging the zoom magnification by the zoom magnification changing means, the white balance correction coefficient stored in the storage means is the second white balance correction coefficient,
When the zoom magnification is reduced by the zoom magnification changing means, the first white balance correction coefficient is set as the second white balance correction coefficient,
An image pickup apparatus that performs white balance control using the second white balance correction coefficient. 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,
White balance evaluation value acquisition processing for acquiring an evaluation value used for white balance control from the imaging signal;
A first white balance correction coefficient calculation process for calculating a first white balance correction coefficient based on the evaluation value acquired by the white balance evaluation value acquisition process;
Zoom magnification change processing for changing the zoom magnification of the optical system;
A storage process for storing a white balance correction coefficient used for white balance control;
A white balance tracking process for setting a white balance tracking speed in accordance with the change in the zoom magnification;
A second white balance correction coefficient calculation process for calculating a second white balance correction coefficient based on the white balance correction coefficient, the first white balance correction coefficient, and the white balance tracking speed stored by the storage process;
An image pickup method comprising: performing white balance correction processing for performing white balance control using the second white balance correction coefficient during zoom magnification change by the zoom magnification change processing. 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,
White balance evaluation value acquisition processing for acquiring an evaluation value used for white balance control from the imaging signal;
A first white balance correction coefficient calculation process for calculating a first white balance correction coefficient based on the evaluation value acquired by the white balance evaluation value acquisition process;
Zoom magnification change processing for changing the zoom magnification of the optical system;
A storage process for storing a white balance correction coefficient used for white balance control;
A white balance tracking process for setting a white balance tracking speed in accordance with the change in the zoom magnification;
A second white balance correction coefficient calculation process for calculating a second white balance correction coefficient based on the white balance correction coefficient, the first white balance correction coefficient, and the white balance tracking speed stored by the storage process;
An imaging program that executes white balance correction processing for performing white balance control using the second white balance correction coefficient during zoom magnification change by the zoom magnification change processing.