JP3959707B2 - Imaging device and white balance control method of imaging device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present inventionHas color video shooting functionEspecially for imaging devicesTakeThe present invention relates to auto white balance control in an imaging apparatus.
[0002]
[Prior art]
  Figure 4 shows the conventionalHas color video shooting functionIt is a block diagram which shows an example of an imaging device.
  The imaging apparatus 102 illustrated in FIG. 4 includes a solid-state imaging device 104, an AFE 106, and a digital signal processing unit 108. The solid-state imaging device 104 has, for example, a CCD structure, detects light from a subject through a lens 110 by a photosensor arranged in a matrix on a semiconductor substrate, generates a signal charge, and the signal charge is converted into a vertical charge transfer register, The image signal of the subject is output after being transferred by the horizontal charge transfer register. Each of the above optical sensors is equipped with red, blue and green primary color filters or complementary color filters such as Mg, Cy and Ye, and color photography is possible by detecting red, blue and green light separately. It has become.
[0003]
  The solid-state image sensor 104 operates based on a clock signal, a vertical synchronization signal, and a horizontal synchronization signal supplied from the timing generator 112 (TG). For example, an image signal for one frame is converted into an even field and an odd number by an interlace method. Output separately to fields.
  An AFE 106 (Analog Front End Processor) includes a CDS circuit and an AGC circuit, and performs CDS (Correlation Double Sampling) on the image signal from the solid-state imaging device 104 to remove fixed pattern noise included in the image signal and AGC. The signal level is stabilized by (automatic gain control).
[0004]
  The digital signal processing unit 108 is a circuit for performing automatic exposure control and auto white balance adjustment on the output signal of the AFE 106, and includes an A / D converter 114, a luminance signal processing unit 116, a color signal processing unit 118, The microcomputer 120 includes an optical detector 122 (OPD 122), a D / A converter 124, and a mixing circuit 126 (YCMIX 126).
[0005]
  The A / D converter 114 digitizes the output signal of the AFE 106, and the luminance signal processing unit 116 performs signal processing on the digitized image signal so as to set the signal level to an appropriate level as automatic exposure control. .
  The color signal processing unit 118 includes a primary color separation circuit 128 and a WB control circuit 130 (white balance control circuit). The primary color separation circuit 128 has three primary colors of red, blue, and green based on the output signal of the A / D converter 114. The signals are separated and extracted, and the WB control circuit 130 multiplies these primary color signals by a coefficient given from the microcomputer 120 to control the signal level.
[0006]
  The OPD 122 integrates the primary color signal multiplied by the coefficient by the WB control circuit 130 for each period of the vertical synchronization signal, that is, for each field, thereby averaging the average signal level (average of each primary color signal in each field). Level).
  The microcomputer 120 includes a CPU, a ROM, and a RAM. The CPU performs various functions by appropriately operating the RAM based on program data stored in the ROM. With regard to the auto white balance control in particular, the above coefficients are generated based on the average level of the primary color signals calculated by the OPD 122 and supplied to the WB control circuit 130 in order to equalize the levels of these primary color signals.
[0007]
  The D / A converter 124 converts the luminance signal output from the luminance signal processing unit 116 and the primary color signal output from the color signal processing unit 118 into analog signals, respectively, and the mixing circuit 126 outputs the luminance signal of these analog signals and the three signals. The primary color signals are combined and a video signal 136 is output.
  The timing generator 112 supplies a clock and a synchronization signal to each unit together with the solid-state image sensor 104 based on the control of the microcomputer 120.
[0008]
  Next, the operation of the imaging apparatus 102 configured as described above will be described.
  Light 132 from the subject enters the solid-state image sensor 104 through the lens 110, and an image of the subject is formed on the light receiving surface of the solid-state image sensor 104. The solid-state image sensor 104 converts this image into an electrical signal, and outputs the image signal of each field in synchronization with the vertical synchronization signal supplied from the timing generator 112. The AFE 106 performs CDS on the image signal output from the solid-state imaging device 104 to remove fixed pattern noise included in the image signal, and stabilizes the signal level by AGC.
[0009]
  The A / D converter 114 digitizes the output signal of the AFE 106, and the luminance signal processing unit 116 performs signal processing on the digitized image signal so as to set the signal level to an appropriate level as automatic exposure control.
  On the other hand, the color signal processing unit 118, the OPD 122, and the microcomputer 120 perform digital signal processing as auto white balance control on the image signal digitized by the A / D converter 114 as follows. FIG. 5 is a timing chart of auto white balance control.
[0010]
  The primary color separation circuit 128 extracts three primary color signals of red, blue, and green from the output signal of the A / D converter 114, and the WB control circuit 130 converts, for example, the primary color signals of red and blue among these primary color signals. On the other hand, the signal level is controlled by multiplying by a coefficient given from the microcomputer 120. The OPD 122 receives the green primary color signal and the red and blue primary color signals multiplied by the coefficients from the WB control circuit 130, and as shown in FIG. 5, for each period of the vertical synchronizing signal, that is, each field Tfn−1. , Tfn, Tfn + 1,... Are integrated to calculate the average level of each primary color signal in each field.
[0011]
  As shown in FIG. 5, the microcomputer 120 takes in the average level of the primary color signal calculated by the OPD 122 at the rising timing Ts1 of the vertical synchronization signal so that the average levels of the three primary color signals are the same. In other words, the coefficients multiplied by the red and blue primary color signals are appropriately increased or decreased so that the average level is uniform, and a new coefficient is supplied to the WB control circuit 130 at the rising timing Ts2 of the next vertical synchronizing signal.
[0012]
  Therefore, in the conventional imaging apparatus 102, as shown in FIG. 5, the coefficient calculation 134 is performed in the field Tfn based on the average level calculated in the previous field Tfn-1, and the new coefficient is the next field. It is supplied to the WB control circuit 130 at the start timing of Tfn + 1 to adjust the level of the primary color signal.
  Thereafter, the three primary color signals output from the color signal processing unit 118 and the image signal output from the luminance signal processing unit 116 are converted into analog signals by the D / A converter 124, synthesized by the mixing circuit 126, and then the video signal. 136 is output.
[0013]
[Problems to be solved by the invention]
  However, in such a conventional imaging apparatus 102, white balance is not completed by one coefficient calculation, and coefficient update is required a plurality of times. Usually, it takes three or more fields before white balance is achieved. It was necessary. Since auto white balance control takes such a long time, a phenomenon called color rolling may occur when the subject is illuminated by a fluorescent lamp.
[0014]
  The fluorescent lamp blinks in a cycle corresponding to the power supply frequency, but the spectral characteristics of the fluorescent lamp change depending on the light emission timing within each blinking cycle, and the light of the fluorescent lamp is not always white. Therefore, when imaging is performed with a short exposure time by the electronic shutter function of the solid-state imaging device, the imaging result is colored depending on the relationship between the exposure timing and the light emission timing of the fluorescent lamp.
  In addition, when the imaging apparatus 102 is compatible with the NTSC (National TV Standards Committee) system and the subject is illuminated by a fluorescent lamp that is lit by a power source of 60 Hz, the field frequency of the imaging apparatus 102 is 59.54 Hz. Since the power supply frequency is slightly different from 60 Hz, the phase relationship between the field of the imaging apparatus 102 and the power supply changes periodically with a relatively long period.
[0015]
  Since the conventional imaging apparatus 102 requires at least three fields to complete auto white balance control as described above, the primary color signal obtained by calculating the average level by the OPD 122 and the primary color signal multiplied by the coefficient by the WB control circuit 130 Is obtained by imaging under illumination light of different color tone, and when the color tone difference of illumination light is large, auto white balance control does not function correctly and the image becomes colored. Since the phase relationship between the field of the imaging device 102 and the power supply changes as described above, the color tone of the video image displayed by the video signal 136 changes periodically according to the change in the phase relationship.
[0016]
  Even when the imaging device 102 is compatible with the PAL (Phase Alternating Line) method and the power supply frequency of the fluorescent lamp is 50 Hz, the field frequency and the power supply frequency of the fluorescent lamp match in the standard, but there is an error in both. Therefore, the color rolling phenomenon occurs as in the case described above.
[0017]
  The present invention has been made to solve such a problem, and an object thereof is to provide an imaging apparatus capable of performing auto white balance control while suppressing a color rolling phenomenon.
[0018]
[Means for Solving the Problems]
  UpTo achieve the purpose,An image pickup apparatus according to the present invention has an image pickup screen in synchronization with a vertical synchronization signal supplied from a timing generator.An image sensor that outputs an image signal representing the primary color separation means that separates a plurality of primary color signals from the image signal, andpluralPrimary signal levelEach ofAverage level ofMore than each otherTo be uniformBeforeRecordpluralControl the primary color signal levelA color video shooting function with a white balance control meansAn imaging device,The white balance control means isAboveverticalThe primary color separation means separated for each period of the synchronization signalpluralPrimary color signal level detection means for acquiring the average level of each primary color signal, and the primary color signal level detection means acquired by the primary color signal level detection meanspluralMultiply the average level of the primary color signal by a factorCoefficient multiplicationMeans and saidCoefficient multiplicationSaid means multiplied by said factorpluralThe average level of the primary color signal isEach otherCoefficient to increase or decrease the coefficient to be more uniformIncrease or decreaseMeans and saidverticalWithin each period of the synchronization signalCoefficient multiplicationMeans and said coefficientsIncrease or decreaseRepetitive control means for activating the means multiple times, and based on the coefficientWhite balanceLevel control amount setting means for setting a level control amount of the primary color signal in the control means.When performing color moving image shooting while continuously executing white balance control, (a) the average level of the primary color signal acquired by the primary color signal level detection means for each period of the vertical synchronization signal is (B) the coefficient multiplication unit within the next cycle of the period in which the average level is acquired with respect to the acquired average level. And the coefficient increasing / decreasing means are activated a plurality of times to perform a coefficient multiplication process and a coefficient increasing / decreasing process, and (c) the acquired average in the period following the period in which the average level of the primary color signal is acquired Completed white balance control based on levelIt is characterized by that.
  In addition, the white balance control method of the imaging apparatus according to the present invention includes an image sensor that outputs an image signal representing an imaging screen in synchronization with a vertical synchronization signal supplied from a timing generator, and a plurality of primary color signals from the image signal. A color moving image photographing function comprising primary color separating means for separating and white balance control means for controlling the levels of the plurality of primary color signals so that the average levels of the levels of the plurality of primary color signals are more uniform with each other; A white balance control method for an image pickup apparatus, wherein the white balance control means obtains the average level of each of the plurality of primary color signals separated by the primary color separation means for each period of the vertical synchronization signal. A primary color signal level detection unit and a front of the plurality of primary color signals acquired by the primary color signal level detection unit; Coefficient multiplying means for multiplying an average level by a coefficient; coefficient increasing / decreasing means for increasing / decreasing the coefficient so that the average levels of the plurality of primary color signals obtained by multiplying the coefficient by the coefficient multiplying means are more uniform to each other; Repeat control means for starting the coefficient multiplication means and coefficient increase / decrease means a plurality of times within each period of the synchronization signal, and a level control amount for setting the level control amount of the primary color signal in the white balance control means based on the coefficients And (a) the primary color signal acquired by the primary color signal level detection means for each period of the vertical synchronization signal when performing color moving image shooting while continuously executing white balance control. The average level is taken into the coefficient multiplication means in synchronization with the vertical synchronizing signal at the end of the period, and (b) With respect to the average level, the coefficient multiplication means and the coefficient increase / decrease means are activated a plurality of times within the period following the period in which the average level is acquired, and the coefficient multiplication process and the coefficient increase / decrease process are performed. ) The white balance control based on the acquired average level is completed within a period following the period in which the average level of the primary color signals is acquired.
[0019]
  In the imaging device of the present invention,Or in the white balance control method of the imaging device of the present invention, when performing color moving image shooting while continuously executing the white balance control,The primary color signal level detecting means isverticalFor each period of the synchronization signal, obtain the average level of each primary color signal separated by the primary color separation means,Coefficient multiplicationThe means multiplies this average level by a factorIncrease or decreaseMeansCoefficient multiplicationMeans multiplied by factorpluralPrimary color signaleachAverage level isEach otherIncrease or decrease the coefficient to be more uniform.Coefficient multiplicationMeans and factorsIncrease or decreaseMeansverticalIt is activated several times by the control means repeatedly for each period of the synchronization signal,pluralA coefficient that makes the average level of the primary color signal uniformverticalObtained for each period of the synchronization signal. And the level control amount setting means is based on this coefficient.White balanceControl meansOkeSet the primary color signal level control amount,White balanceThe control means outputs a primary color signal whose average level is uniform, that is, a primary color signal subjected to white balance control.
[0020]
  Therefore, in the present invention,When performing color video shooting while continuously executing white balance control,The white balance control can be completed in one period of the synchronization signal,This verticalThe synchronizing signal is, for example, a vertical synchronizing signal in the NTSC systemIsIn this case, white balance control can be performed in a period of one field. Conventionally, white balance control requires 3 fields or more, and in the present invention, it is shortened to 1/3 or less, so that the color rolling phenomenon can be greatly suppressed.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
  Next, embodiments of the present invention will be described with reference to the drawings.
  FIG. 1A is according to the present invention.Has color video shooting functionFIG. 2B is a block diagram illustrating an example of an imaging apparatus, and FIG. 3B is a block diagram functionally illustrating a microcomputer that configures the imaging apparatus. FIG. 2 is a timing chart showing the auto white balance control in the present embodiment, and FIG. 3 is a flowchart showing the operation of the imaging apparatus of FIG. In FIG. 1, the same elements as those in FIG. 4 are denoted by the same reference numerals, and detailed description thereof will be omitted here.
[0022]
  The imaging apparatus 2 of the present embodiment shown in FIG. 1 is different from the imaging apparatus of FIG. 4 particularly in terms of functions performed by the microcomputer 120 that constitutes the digital signal processing unit 4. That is, as shown in FIG. 1B, the microcomputer 120 is functionallyCoefficient multiplicationMean 6, coefficientIncrease or decreaseMeans 8, repeat control means 10, and level control amount setting means 14 are included.Coefficient multiplicationThe means 6 multiplies the average level of the red and blue primary color signals acquired by the OPD 122 (primary color signal level detection means according to the present invention) by a coefficient,Increase or decreaseMeans 8 includes an average level of green, andCoefficient multiplicationThe means 6 increases or decreases the coefficient by a certain amount so that the average level of the primary color signals of red and blue multiplied by the coefficient becomes more uniform.
[0023]
  The repetitive control means 10 is used for each period of the vertical synchronizing signal, that is, for each field.Coefficient multiplicationMean 6 and coefficientIncrease or decreaseThe means 8 is activated a plurality of times. The level control amount setting means 14 determines the WB control circuit 1 based on the coefficients related to the red and blue primary color signals obtained as a result.6The level control amount of the primary color signal is set. Specifically, the WB control circuit 16 includes a multiplier as an example, and the level control amount setting means 14 supplies the coefficient (or a numerical value corresponding to the coefficient) to the WB control circuit 16 in the present embodiment. By supplying, the level control amount in the WB control circuit 16 is set. The WB control circuit 16 controls the signal level of the primary color signal by multiplying the primary color signal by the multiplier (or the numerical value) supplied from the level control amount setting means 14 by the multiplier.
[0024]
  Next, the operation of the imaging apparatus 2 configured as described above will be described in detail with reference to FIGS.
  Light 132 from the subject enters the solid-state image sensor 104 through the lens 110, and an image of the subject is formed on the light receiving surface of the solid-state image sensor 104 (image sensor). The solid-state image sensor 104 converts this image into an electrical signal, and outputs the image signal of each field in synchronization with the vertical synchronization signal supplied from the timing generator 112. The AFE 106 performs CDS on the image signal output from the solid-state imaging device 104 to remove fixed pattern noise included in the image signal, and stabilizes the signal level by AGC.
  The A / D converter 114 digitizes the output signal of the AFE 106, and the luminance signal processing unit 116 performs signal processing on the digitized image signal so as to set the signal level to an appropriate level as automatic exposure control.
[0025]
  on the other hand,When performing color video shooting while continuously executing white balance control,The color signal processing unit 119, the OPD 122, and the microcomputer 120 perform digital signal processing as auto white balance control on the image signal digitized by the A / D converter 114 as follows.
  The primary color separation circuit 128 extracts the three primary color signals of red, blue, and green from the output signal of the A / D converter 114, and the WB control circuit 16 outputs the primary color signal of red and blue among these primary color signals. Then, the signal level is controlled by multiplying the coefficient given from the microcomputer 120. In the present embodiment, the OPD 122 receives the primary color signals of red, blue, and green from the primary color separation circuit 128 and, as shown in FIG. 2, for each period of the vertical synchronization signal, that is, each field Tfn−1. , Tfn, Tfn + 1,... Are integrated to calculate the average level of each primary color signal in each field.
[0026]
  And the repetition control means 10 by the microcomputer 120 is a coefficientIncrease or decreaseThe means 8 is activated three times for each field as an example in this embodiment,Coefficient multiplicationMeans 6 is activated twice.
  coefficientIncrease or decreaseWhen the means 8 is activated by the repetitive control means 10, the data of the average level of the primary color signal calculated by the OPD 122 as described above is fetched at the rising timing Ts1 (FIG. 2) of the vertical synchronization signal (step S1). The ratio of the average levels of red, blue, and green is checked to determine whether or not the white balance control is within the pull-in range (step S2). The white balance should not be performed when the subject's original color is a particularly high proportion of a specific color, such as red or blue.Increase or decreaseThe means 8 determines that it is outside the pull-in range (No in step S2), and in this case, white balance control is not performed.
[0027]
  On the other hand, if the ratio of the average levels of red, blue, and green is within the pull-in range of white balance control (Yes in step S2), the coefficientIncrease or decreaseThe means 8 checks whether or not the ratio R: G: B of the average levels of the primary color signals of red, green and blue is 1: 1: 1 (step S3). If the ratio of the average levels of the primary color signals is not 1: 1: 1 (No in step S3), the coefficientIncrease or decreaseThe means 8 checks whether or not the average level of the red primary color signal is greater than the average level of the green primary color signal (step S4). If the average level of red is greater than the average level of green (Yes in step S4). The coefficient value for the red primary color signal is decreased by a certain amount (step S5). Conversely, when the red average level is equal to or lower than the green average level (No in step S4), the coefficient value for the red primary color signal is changed. Increase by a certain amount (step S6).
[0028]
  In addition, the coefficientIncrease or decreaseThe means 8 checks whether or not the average level of the blue primary color signal is greater than the average level of the green primary color signal (step S7). If the blue average level is greater than the green average level (Yes in step S7). The coefficient value for the blue primary color signal is decreased by a certain amount (step S8). Conversely, when the blue average level is equal to or lower than the green average level (No in step S7), the coefficient value for the red primary color signal is changed. Increase by a certain amount (step S9). In addition, the process of step S1-S9 is shown as the coefficient calculation process 18 in FIG.
[0029]
  AndCoefficient multiplicationMean 6 is a coefficientIncrease or decreaseCoefficients for the red and blue primary color signals are received from the means 8, and the average levels of the red and blue primary color signals acquired by the OPD 122 are multiplied by these coefficients, respectively (step S10). This process is represented by the multiplier symbol 20 in FIG.
  Then coefficientIncrease or decreaseThe means 8 is activated again by the repeat control means 10 andCoefficient multiplicationThe average level of the red and blue primary color signals after multiplying by the coefficient is received from the means 6, and the processing of steps S2 to S9 is repeated.Coefficient multiplicationThe means 6 is activated by the repetitive control means 10 and performs step S10.
[0030]
  In addition, the coefficientIncrease or decreaseThe means 8 is activated by the repetition control means 10 and repeats the processing of steps S2 to S9. The level control amount setting means 14Increase or decreaseThe coefficient related to the red and blue primary color signals calculated by the means 8 is output to the WB control circuit 16 at the beginning of the next field, that is, at the next rising timing Ts2 of the vertical synchronizing signal. The WB control circuit 16 receives the coefficients for the red and blue primary color signals from the level control amount setting means 14, and based on each coefficient, determines the signal levels of the red and blue primary color signals supplied from the primary color separation circuit 128 in the next field. The result is output to the D / A converter 124 together with the green primary color signal.
[0031]
  As described above, in the imaging device 2 of the present embodiment,When performing color video shooting while continuously executing white balance control,The white balance process is performed substantially three times within the period of one field (Tf). Therefore, the white balance control can be completed within the period of one field. Conventionally, since the white balance control has required time of three fields or more, in this embodiment, the time is reduced to 1/3 or less, and thus the color rolling phenomenon can be greatly suppressed.
[0032]
  In this embodiment, the coefficientIncrease or decreaseThe means 8 increases or decreases the coefficients for the primary color signals of red and blue, but may be configured to increase or decrease the coefficients for the primary color signals of other colors such as red and green. Multiply the primary color signal by a coefficient,Increase or decreaseMeans 8 calculates coefficients for all primary color signals of red, blue and green.Increase or decreaseIt is also possible to adopt a configuration.
  In this embodiment, the coefficientIncrease or decreaseAlthough the means 8 calculates the coefficient three times during one field period, it is of course possible to set the number of times twice or four times or more.
[0033]
【The invention's effect】
  As described above, in the imaging apparatus of the present invention,Or in the white balance control method of the imaging device of the present invention, when performing color moving image shooting while continuously executing the white balance control,The primary color signal level detecting means isverticalFor each period of the synchronization signal, obtain the average level of each primary color signal separated by the primary color separation means,Coefficient multiplicationThe means multiplies this average level by a factorIncrease or decreaseMeansCoefficient multiplicationMeans multiplied by factorpluralPrimary color signaleachAverage level isEach otherIncrease or decrease the coefficient to be more uniform.Coefficient multiplicationMeans and factorsIncrease or decreaseMeansverticalIt is activated multiple times by the repetitive control means for each period of the synchronization signal, and as a result, a coefficient that satisfactorily equalizes the average level of the primary color signal is obtained.verticalObtained for each period of the synchronization signal. And the level control amount setting means is based on this coefficient.White balanceControl meansOkeSet the primary color signal level control amount,White balanceThe control means outputs a primary color signal whose average level is uniform, that is, a primary color signal subjected to white balance control.
[0034]
  Therefore, in the present invention,When performing color video shooting while continuously executing white balance control,The white balance control can be completed in one period of the synchronization signal,This verticalThe synchronizing signal is, for example, a vertical synchronizing signal in the NTSC systemIsIn this case, white balance control can be performed in a period of one field. Conventionally, white balance control requires 3 fields or more, and in the present invention, it is shortened to 1/3 or less, so that the color rolling phenomenon can be greatly suppressed.
[Brief description of the drawings]
FIG. 1 (A) is in accordance with the present invention.Has color video shooting functionFIG. 2B is a block diagram illustrating an example of an imaging apparatus, and FIG. 3B is a block diagram functionally illustrating a microcomputer that configures the imaging apparatus.
FIG. 2 is a timing chart showing auto white balance control in the present embodiment.
3 is a flowchart showing the operation of the imaging apparatus of FIG.
FIG. 4 is a block diagram illustrating an example of a conventional imaging apparatus.
FIG. 5 is a timing chart showing conventional auto white balance control.
[Explanation of symbols]
  2 ... Imaging device, 4 ... Digital signal processor, 6 ...Coefficient multiplicationMeans, 8 ... coefficientIncrease or decreaseMeans, 10 ... Repeat control means, 14 ... Level control amount setting means, 16 ... WB control circuit, 104 ... Solid-state image sensor, 106 ... AFE, 110 ... Lens, 112 ... Timing generator, 114 ... ... A / D converter, 116 ... Luminance signal processor, 119 ... Color signal processor, 120 ... Microcomputer, 122 ... Optical detector (OPD), 124 ... D / A converter, 126 ... Mixing circuit (YCMIX), 128... Primary color separation circuit.

Claims (7)

An image sensor that outputs an image signal representing an imaging screen in synchronization with a vertical synchronization signal supplied from a timing generator , primary color separation means that separates a plurality of primary color signals from the image signal, and a level of the plurality of primary color signals an imaging apparatus having a color video shooting function and a white balance control means for each of the average level to control the level of uniform and so as to pre-Symbol plurality of primary color signals from each other,
The white balance control means is
Primary color signal level detection means for acquiring the average level of each of the plurality of primary color signals separated by the primary color separation means for each period of the vertical synchronization signal;
Coefficient multiplication means for multiplying the average level of the plurality of primary color signals acquired by the primary color signal level detection means by a coefficient;
A coefficient adjusting unit that said coefficient multiplying means for increasing or decreasing the coefficient the like mean level becomes more uniform with each other of said plurality of primary color signals multiplied by the coefficient,
Repetitive control means for activating the coefficient multiplying means and the coefficient increasing / decreasing means a plurality of times within each period of the vertical synchronization signal;
Level control amount setting means for setting a level control amount of the primary color signal in the white balance control means based on the coefficient ,
When performing color moving image shooting while continuously executing white balance control, (a) the average level of the primary color signal acquired by the primary color signal level detection means for each period of the vertical synchronization signal is the end of the period. (B) the coefficient multiplication means within the next cycle of the period in which the average level is acquired with respect to the acquired average level. And the coefficient increasing / decreasing means is activated a plurality of times to perform coefficient multiplication processing and coefficient increasing / decreasing processing, so that (c) the acquired average level within the period following the period in which the average level of the primary color signal is acquired The white balance control based on
An imaging apparatus characterized by that. 2. The imaging apparatus according to claim 1, wherein the primary color signal level detecting means calculates an integrated value of the primary color signals for each imaging screen as the average level.   2. The imaging apparatus according to claim 1, wherein the primary color separation unit separates primary color signals of red, blue, and green from an output signal of the image sensor. 2. The imaging apparatus according to claim 1, wherein the coefficient multiplying unit multiplies the coefficient by the average level of at least two of the primary color signals. 2. The imaging apparatus according to claim 1, wherein the image sensor outputs the image signal in an interlaced manner, and the vertical synchronization signal is a synchronization signal for outputting an image signal of each field. The vertical synchronizing signal capturing apparatus according to claim 1, characterized in that the vertical synchronizing signal in the NTSC or PAL. An image sensor that outputs an image signal representing an imaging screen in synchronization with a vertical synchronization signal supplied from a timing generator, primary color separation means that separates a plurality of primary color signals from the image signal, and a level of the plurality of primary color signals A white balance control method for an image pickup apparatus having a color moving image shooting function, comprising a white balance control means for controlling the levels of the plurality of primary color signals so that the respective average levels are more uniform with each other,
The white balance control means;
Primary color signal level detection means for acquiring the average level of each of the plurality of primary color signals separated by the primary color separation means for each period of the vertical synchronization signal;
Coefficient multiplication means for multiplying the average level of the plurality of primary color signals acquired by the primary color signal level detection means by a coefficient;
The average levels of the plurality of primary color signals multiplied by the coefficient by the coefficient multiplier are mutually different. Coefficient increasing / decreasing means for increasing / decreasing the coefficient to be more uniform,
Repetitive control means for activating the coefficient multiplying means and the coefficient increasing / decreasing means a plurality of times within each period of the vertical synchronization signal;
A level control amount setting means for setting a level control amount of the primary color signal in the white balance control means based on the coefficient;
When performing color moving image shooting while continuously executing white balance control, (a) the average level of the primary color signal acquired by the primary color signal level detection means for each cycle of the vertical synchronization signal is set to the end of the cycle. (B) the coefficient multiplication means and the coefficient multiplication means and the coefficient multiplication means in the period next to the period in which the average level is acquired with respect to the fetched average level. The coefficient increasing / decreasing means is activated a plurality of times to perform coefficient multiplication processing and coefficient increasing / decreasing processing, so that (c) white based on the acquired average level within the period after the average level of the primary color signal is acquired Completed the balance control,
A white balance control method for an image pickup apparatus.

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