JP4481389B2 - Imaging device, white balance adjustment method thereof, and storage medium - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an imaging apparatus having an incident light amount adjustment function and a white balance adjustment function, a white balance adjustment method thereof, and a storage medium.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, an imaging apparatus such as a video camera has an automatic exposure control function (AE function) and opens an aperture configured by one or a plurality of aperture blades inserted in a lens optical axis according to the brightness of a subject. The degree of light is adjusted so that the amount of light incident on the image sensor becomes a predetermined value.
[0003]
Therefore, when photographing a bright subject with automatic exposure control, the aperture diameter of the aperture blade becomes small, so light diffraction occurs at the edge of the aperture blade, and if it is brighter, the image quality deteriorates, such as overexposure. .
[0004]
In order to prevent such deterioration in image quality, conventionally, a small ND filter is pasted on the aperture blade, and the ND filter is inserted on the optical axis of the lens in conjunction with the aperture operation, so that the aperture of a bright subject is reduced. By keeping the opening degree above a certain level, the aperture diameter is prevented from becoming too small, and the adjustment range of the amount of light incident on the imaging surface is widened.
[0005]
Here, the ND (Neutral Density) filter is a filter having an arbitrary transmittance in a wide wavelength band in order to reduce the amount of transmitted light.
[0006]
Also, a device that directly inserts the ND filter into the optical axis without attaching the ND filter to the aperture blade is provided separately from the aperture device, and when photographing a bright subject, the ND filter is manually inserted into the optical axis. Alternatively, there is also known a light amount adjustment method for automatically controlling the insertion and removal of the ND filter into and from the optical axis in accordance with the incident light amount detected by the light amount detection means (Japanese Patent Laid-Open No. 5-292392).
[0007]
On the other hand, in an imaging device such as a video camera, a function for automatically adjusting the RGB signal output ratio, so-called auto white balance (AWB) so that stable and good color reproduction can be obtained even when the color temperature of the light source changes. ) It has a function.
[0008]
In this auto white balance, generally, color information in a process of generating a video signal by an electric signal from an image sensor is read in one field unit, and the white balance is adjusted based on the read color information.
[0009]
Such an adjustment method is called an internal measurement method, and control is performed on the assumption that “when the white balance is properly adjusted, the entire screen is averaged to become achromatic”.
[0010]
For an actual subject, this precondition is met only when shooting a general landscape with various colors mixed randomly, for example, up of the subject's flowers against a blue sky, green leaves, etc. When the image is taken, it does not hold, and on average, it becomes a color biased to a single color such as blue or green.
[0011]
For such subjects, the internal white balance adjustment is controlled so that the white balance is adjusted by considering it as an achromatic color even though the average color of the screen is not an achromatic color. It will deviate greatly from.
[0012]
For this reason, conventionally, the following measures are taken in the control of the internal measurement type white balance adjustment. FIG. 14 is a diagram showing white movement due to a change in color temperature on the vector scope. This is a representation of the movement of white when the color temperature is changed as a parameter on a vector scope having (R−Y) as the vertical axis and (B−Y) as the horizontal axis, which are color difference components of the video signal. .
[0013]
In the figure, if the white balance is properly adjusted under a light source of an arbitrary color temperature and white is positioned on the intersection of the vertical and horizontal axes (zero color difference component), as the color temperature decreases, While moving in the direction of the arrow 1 along the I axis, it shows the characteristic of moving in the direction of the arrow 2 along the I axis as the color temperature increases. Here, a curve connecting white positions is hereinafter referred to as a color temperature change axis.
[0014]
By using this characteristic, the range that can be adjusted when performing white balance adjustment is limited to a narrow area close to the I-axis, and adjustment is not performed outside the area. Even when shooting, the amount of white balance adjustment is reduced in the green-magenta direction, and the problem is reduced.
[0015]
In fact, not only natural light (sun) but also artificial light (fluorescent light, incandescent light) that does not ride on the color temperature change axis, these light sources are included to adjust the white balance appropriately. The adjustment control range is set. FIG. 15 is a diagram showing a control range of white balance adjustment.
[0016]
When adjusting the white balance by fixing the gain of G and changing only the gains of R and B in order to make the output ratio of the RGB signal constant, for various light sources indoors and outdoors The relationship between the R gain and B gain when white balance adjustment is properly performed (indicated by x in FIG. 15) is expressed as B gain on the vertical axis and R gain on the horizontal axis. The control range of white balance adjustment is set so as to include the x mark in FIG.
[0017]
In order to eliminate the influence of colors other than white as much as possible and increase white balance adjustment accuracy, it is necessary to keep the adjustment control range to the minimum necessary.
[0018]
[Problems to be solved by the invention]
However, the above conventional imaging apparatus has the following problems, and improvement has been demanded. That is, regarding the ND filter, the ideal spectral characteristic of the ND filter is that the transmittance is uniform in the wavelength band of the visible light region, but in reality there is a difference in transmittance between the wavelengths. .
[0019]
For this reason, when the light from the subject passes through the ND filter, the color reproduction is shifted. If the white balance is properly adjusted in a state where the ND filter is not inserted on the optical axis, there is a possibility that the white balance is shifted due to the ND filter being inserted on the optical axis. It was.
[0020]
Thus, not only the ND filter but also various electro-optical elements are used, the correction method is already known for correcting the image with respect to the color tone change caused by the insertion of the ND filter and the change in the light shielding ratio of the various electro-optical elements. (Japanese Patent Publication No. 63-56528). That is, in order to correct the white balance deviation due to the insertion of the ND filter, the white balance deviation amount is grasped in advance, and the control value corresponding to the white balance deviation amount is corrected after the ND filter is inserted. .
[0021]
However, regarding the performance and accuracy of white balance adjustment, the control range of white balance adjustment is set with no margin for the assumed light source, so if the color reproducibility for each light source changes, The performance and accuracy of the white balance adjustment are significantly reduced, and the white balance cannot be adjusted properly depending on the direction of the white balance shift and the type of light source.
[0022]
Such a problem cannot be solved simply by correcting the image with respect to the color change.
[0023]
On the other hand, when driving the ND filter, there is a problem in correcting the white balance deviation by the ND filter depending on the timing of insertion on the optical axis or removal from the optical axis. FIG. 16 is a diagram showing changes in the ND filter insertion timing and WB shift amount. In the period of an arbitrary field n, (n + 1), (n + 2), (n + 3) of the video signal, insertion of the ND filter is started from the middle of the (n + 1) field, and insertion of the ND filter is performed in the middle of the (n + 2) field. When several fields are required for driving the ND filter as described above, the positional relationship between the ND filter in operation and the imaging surface of the imaging element changes for each field, so in the (n + 1) and (n + 2) fields, A difference occurs in the degree of influence of the ND filter on the image.
[0024]
In other words, when the white balance is appropriately adjusted by reading out color information for each field of n, (n + 1), and (n + 2), the white in the (n + 3) field where the ND filter is entirely in the screen. There is a difference in the amount of deviation of the balance (WB deviation amounts 0, 1, and 2 in FIG. 15), and the required correction amounts are also different.
[0025]
Moreover, the WB deviation amount 1 and the WB deviation amount 2 change depending on the timing of the ND filter insertion start point and end point in the (n + 1) and (n + 2) fields. Under such circumstances, it is not possible to appropriately correct the white balance deviation caused by the ND filter.
[0026]
Therefore, the present invention provides an imaging apparatus capable of maintaining a good color reproduction of a captured image by realizing appropriate white balance adjustment without being affected by the state of the ND filter, and the white balance adjustment thereof. It is an object to provide a method and a storage medium.
[0028]
[Means for Solving the Problems]
To achieve the above object, the present invention Shoot An image device converts an optical signal from a subject incident through a lens into an electrical signal by an imaging device, and performs signal processing on the converted electrical signal to generate a video signal. A light amount adjustment filter for adjusting the amount of incident light, and the light amount adjustment filter are driven in a direction in which incident light from the lens is inserted into a position on the optical axis reaching the image sensor or a direction in which the light is extracted from the position on the optical axis. And a white balance adjustment control means for adjusting a white balance of the generated video signal. The white balance adjustment control means includes white balance adjustment control data for adjusting the white balance. White balance adjustment control that limits the values that the generated white balance adjustment control data can take Provided with a circumference, if the light amount adjustment filter is inserted to a position on the optical axis , The white balance adjustment control range is changed.
[0036]
In order to achieve the above object, the present invention The white balance adjustment method of an imaging device is an imaging device that converts an optical signal from a subject incident through a lens into an electrical signal by an imaging device and generates a video signal by performing signal processing on the converted electrical signal. In the white balance adjustment method, a light amount adjustment filter that adjusts the amount of incident light from the lens is inserted in a position on the optical axis where the incident light from the lens reaches the image sensor, or from a position on the optical axis. A process of driving in the pulling direction;
A step of generating white balance adjustment control data for adjusting white balance of the generated video signal, and the light amount adjustment filter being inserted at a position on the optical axis; , And a step of changing a white balance adjustment control range that limits a value that can be taken by the generated white balance adjustment control data.
[0039]
To achieve the above object, the present invention The storage medium includes a computer that controls an imaging device that converts an optical signal from a subject incident through a lens into an electrical signal by an imaging device and performs signal processing on the converted electrical signal to generate a video signal. In a storage medium that is executed and stores a program for adjusting white balance of the generated video signal, the program includes a light amount adjustment filter that adjusts the amount of incident light from the lens, and the incident light from the lens A procedure for driving in a direction to insert in a position on the optical axis leading to the image sensor or a direction to remove from the position on the optical axis, and white balance adjustment control data for adjusting the white balance of the generated video signal When generating and when the light amount adjustment filter is inserted at a position on the optical axis , And a procedure for changing a white balance adjustment control range that limits a value that can be taken by the generated white balance adjustment control data.
[0042]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of an imaging apparatus, a white balance adjustment method thereof, and a storage medium according to the present invention will be described.
[0043]
[First Embodiment]
FIG. 1 is a block diagram illustrating the configuration of the imaging apparatus according to the first embodiment. In the figure, reference numeral 11 denotes a lens for imaging a subject. Reference numeral 12 denotes an aperture for adjusting the amount of light. Reference numeral 13 denotes an image sensor (CCD) that converts input light into an electrical signal. A sample hold (S / H) / AGC unit 14 performs sample hold and gain adjustment.
[0044]
Reference numeral 15 denotes an A / D conversion unit that performs analog-digital conversion (A / D conversion). Reference numeral 16 denotes a video signal processing unit that performs signal processing to generate a video signal. Reference numeral 17 denotes a video signal output terminal. Reference numeral 18 denotes an ND filter. Reference numeral 19 denotes an ND filter driving unit that drives the ND filter 18. Reference numeral 20 denotes an ND on / off key operated by an operator in order to switch the ND filter 18 on / off.
[0045]
A white balance control unit 21 controls white balance adjustment. A system control unit 22 controls the entire imaging apparatus, and includes a white balance control unit 21. Reference numeral 23 denotes an ND filter position detector that detects the position of the ND filter 18.
[0046]
The amount of light from the subject received through the lens 11 is adjusted by the diaphragm 12 and imaged on the surface of the image sensor 13. When converted into an electrical signal by the image sensor 13, the electrical signal is input to the sample hold / AGC unit 14, A / D converted by the A / D converter 15, and then input to the video signal processor 16. .
[0047]
The video signal processing unit 16 performs processing such as aperture correction, gamma correction, and white balance adjustment on the input signal for each luminance and color component to generate and output a video signal. The output video signal is input to a recording device or the like connected to the output terminal 17.
[0048]
The ND filter driving unit 19 turns the ND filter 18 on or off depending on the state of the ND on / off key 20. Here, turning on the ND filter 18 means driving the ND filter 18 in a direction to be inserted into a position on the optical axis of the lens 11, and turning off the ND filter 18 means a position on the optical axis of the lens 11. It is to drive in the direction not inserted in. The ND filter position detection unit 23 detects whether the ND filter 18 is in an on position or an off position, and outputs a detection signal to the system control unit 22.
[0049]
FIG. 2 is a block diagram showing an electrical configuration of the system control unit 22. The system control unit 22 has a configuration in which a known CPU 31, ROM 32, RAM 33, and I / O interface (I / F) 34 are connected via a bus 35.
[0050]
Next, the white balance adjustment of the video signal processing unit 16 by the white balance control unit 21 will be described. FIG. 3 is a flowchart showing a white balance adjustment processing procedure. This processing program is stored in the ROM 32 in the system control unit 22 and is executed by the CPU 31. That is, the white balance control unit 21 is realized by the CPU 31 executing the white balance adjustment processing program module. A white balance control unit can be provided separately from the system control unit.
[0051]
First, it is determined whether or not reading of color information for each field related to a video signal, which is information necessary for white balance adjustment, from the video signal processing unit 16 is finished (step S301).
[0052]
If the reading of the color information has not been completed, the process of step S301 is repeated again. If the reading of the color information has been completed, the read color information is averaged (step S302), and the averaged color Based on the information, white balance adjustment control data is calculated (step S303).
[0053]
Then, the state of the ND filter 18 is determined based on the detection signal from the ND filter position detection unit 23 (step S304). When the ND filter 18 is in the OFF position, the control range for white balance adjustment is set for the ND filter OFF state (step S305). On the other hand, when the ND filter 18 is in the ON position, the control range for white balance adjustment is set for the ND filter ON state (step S306).
[0054]
It is determined whether or not the white balance adjustment control data calculated in step S303 is within the set control range (step S307). If the white balance adjustment control data is within the control range, the process proceeds to step S309 as it is. If not, the white balance adjustment control data is limited within the control range (step S308).
[0055]
Then, the white balance adjustment control data is output to the video signal processing unit 16 (step S309). Thereafter, the process returns to step S301 and the same process is repeated.
[0056]
FIG. 4 is a diagram showing a control range of white balance adjustment. In the figure, the range surrounded by the solid line is the control range when the ND filter 18 is set off in step S305, and the range surrounded by the dotted line is the control range when the ND filter 18 is set in step S306. It is. In each of the cases where the ND filter 18 is turned on and off, the R gain and B gain control ranges are set so that white balance adjustment can be appropriately performed for various light sources indoors and outdoors. That is, as explained in the prior art (see FIG. 15), the control range is such that the gain of G is fixed and only the gains of R and B are varied in order to keep the output ratio of RGB signals constant. When white balance adjustment is performed, the relationship between R gain and B gain when white balance adjustment is appropriately performed for various light sources indoors and outdoors is shown.
[0057]
Thus, in the white balance adjustment of the video signal processing unit 16 by the white balance control unit 21, the control range of the white balance adjustment is changed by turning the ND filter 18 off and on, and the white balance adjustment control data is within the respective control range. It is controlled so that it always fits.
[0058]
In the present embodiment, the control for moving the ND filter 18 in and out of the optical axis is performed by the operation of the ND on / off key 20 by the operator. However, in the case of an imaging device having a light amount detection means, the detected or imaged subject Depending on the amount of light, the insertion and removal of the ND filter may be controlled automatically.
[0059]
Furthermore, in the present embodiment, the control range of the white balance adjustment is changed and the white balance adjustment control data is restricted instantaneously. However, the value of the white balance adjustment control data is increased by these control operations. If there is a problem that the color change of the generated video signal is unnatural, the control range or the control data may be switched step by step.
[0060]
In addition, when it takes time to drive the ND filter on / off, the control range or the white balance adjustment control data may be switched stepwise in conjunction with the movement of the ND filter.
[0061]
Further, the driving method of the ND filter 18 driven by the ND filter driving unit 19 in accordance with the ND on / off key 20 is not particularly limited, and for example, it is mechanically driven by an electrically driven method. Either method can be used.
[0062]
Further, the shape, size, and position of the control range for white balance adjustment, that is, the values that can be taken by the white balance control data are not particularly limited, and the shape of the control range between when the ND filter is off and when it is on, The size may be different.
[0063]
For example, the relationship between the R gain and the B gain when appropriate white balance adjustment is performed under various light sources when the ND filter is off is indicated by a cross in the solid line frame in FIG. 5, and when the ND filter is off. The control range is different in shape, size, and position from the control range of FIG. FIG. 5 is a diagram showing another control range in white balance adjustment. When the ND filter is turned on and the relationship between the R gain and B gain when appropriate white balance adjustment is performed under various light sources moves in the direction of the arrow in FIG. 5, the dotted frame indicates that the ND filter is turned on. It becomes the control range of the hour.
[0064]
FIG. 6 is a diagram showing another control range in white balance adjustment. The relationship between the R gain and the B gain when appropriate white balance adjustment is performed under various light sources when the ND filter is off is indicated by a cross in the solid line frame in FIG. When the ND filter is on and only the relationship between the R gain and the B gain when proper white balance adjustment is performed under incandescent and white fluorescent lights, the dotted frame Is the control range when the ND filter is on. Therefore, the control range when the ND filter is on is not the same as the control range when the ND filter of FIG. 4 is off, but the control range is different.
[0065]
[Second Embodiment]
FIG. 7 is a block diagram illustrating a configuration of the imaging apparatus according to the second embodiment. 7 are the same as those shown in FIG. 1 of the first embodiment, and thus the description thereof is omitted.
[0066]
Also in the operation of the image pickup apparatus, the components other than the ND filter driving unit 19 and the white balance control unit 21 are the same as those in the first embodiment, and thus description thereof is omitted.
[0067]
The ND filter driving unit 19 turns the ND filter 18 on or off depending on the state of the ND on / off key 20. Here, turning on the ND filter 18 means driving the ND filter 18 in a direction to be inserted into a position on the optical axis of the lens 11, and turning off the ND filter 18 means a position on the optical axis of the lens 11. It is to drive in the direction not inserted in. Further, the ND filter drive unit 19 outputs a drive information signal indicating that the ND filter 18 has been driven to the on or off position to the system control unit 22.
[0068]
Next, the white balance adjustment of the video signal processing unit 16 by the white balance control unit 21 will be described, which is basically the same as that in the first embodiment. That is, the processing in steps S301 to S303 in FIG. 3 is performed, and after the processing in step S303, in step S304, unlike the first embodiment, in the second embodiment, the driving information signal from the ND filter driving unit 19 is used. The state of the ND filter 18 is determined.
[0069]
As in the first embodiment, when the ND filter 18 is in the off position, the process of step S305 is performed. When the ND filter 18 is in the on position, the process of step S306 is performed.
[0070]
Thus, in the white balance adjustment of the video signal processing unit 16 by the white balance control unit 21, the control range of the white balance adjustment is changed by turning the ND filter 18 off and on, and the white balance adjustment control data is within each control range. It is controlled so that it always fits.
[0071]
In the second embodiment, the state of the ND filter 18 is determined by the drive information signal indicating the drive state from the ND filter drive unit 19, but the system control unit 22 or the white balance control unit 21 performs the ND on / off key. You may judge by reading 20 states directly.
[0072]
[Third Embodiment]
FIG. 8 is a block diagram illustrating a configuration of an imaging apparatus according to the third embodiment. The same reference numerals are used for the same components as those in the first and second embodiments.
[0073]
In the figure, reference numeral 11 denotes a lens for imaging a subject. Reference numeral 12 denotes an aperture for adjusting the amount of light. Reference numeral 13 denotes an image sensor (CCD) that converts input light into an electrical signal. Reference numeral 14 denotes a sample hold / AGC unit for performing sample hold and gain adjustment.
[0074]
Reference numeral 15 denotes an A / D conversion unit that performs analog-digital conversion (A / D conversion). Reference numeral 16 denotes a video signal processing unit that performs signal processing to generate a video signal. Reference numeral 17 denotes a video signal output terminal. Reference numeral 18 denotes an ND filter.
[0075]
Reference numeral 19 denotes an ND filter driving unit that drives the ND filter. Reference numeral 23 denotes an ND filter position detector that detects the position of the ND filter. An ND filter control unit 24 controls the driving of the ND filter. A white balance control unit 21 controls white balance adjustment.
[0076]
A system control unit 22 controls the entire imaging apparatus, and includes an ND filter control unit 24 and a white balance control unit 21. Reference numeral 20 denotes an ND on / off key operated by an operator in order to switch the ND filter on / off. Reference numeral 25 denotes a WB auto / set key that is operated by an operator to switch the auto / set mode of white balance adjustment. Reference numeral 26 denotes a camera operation key unit on which keys for operating the image sensor are arranged, and includes an ND on / off key 20 and a WB auto / set key 25.
[0077]
The light from the subject received through the lens 11 is adjusted in light quantity by the diaphragm 12 and imaged on the surface of the image sensor 13. When converted into an electrical signal by the image sensor 13, the electrical signal is input to the sample hold / AGC unit 14, A / D converted by the A / D converter 15, and then input to the video signal processor 16. .
[0078]
The video signal processing unit 16 performs signal processing such as aperture correction, gamma correction, and white balance adjustment on the input signal for each luminance and color component to generate and output a video signal. The output video signal is input to a recording device or the like connected to the output terminal 17.
[0079]
The system control unit 22 has the same electrical configuration as shown in FIG. 1 as in the first embodiment. The ND filter control unit 24 and the white balance control unit 21 are realized by the CPU 31 in the system control unit executing the control program stored in the ROM 32. In addition to the system control unit, an ND filter control unit and a white balance control unit may be realized.
[0080]
The system control unit 22 controls each unit of the imaging device according to the state of the keys arranged in the camera operation key unit 26, and turns on or off the ND filter 18 according to the state of the ND on / off key 20. According to the state of the WB auto / set key 25, the ND filter control unit 24 and the white balance control unit 21 are controlled in order to set the white balance adjustment mode to auto or set.
[0081]
Here, turning on the ND filter 18 means driving the ND filter 18 in a direction to be inserted into a position on the optical axis of the lens 11, and turning off the ND filter 18 means a position on the optical axis of the lens 11. It is to drive in the direction not inserted in.
[0082]
In the white balance adjustment mode, auto is an operation mode in which adjustment is performed so that the white balance is always properly maintained so as to follow changes in the light source of the subject. Set is an operation mode in which the white balance of the subject image at the moment when the mode is switched from auto to set is adjusted to be appropriate, and when the adjustment is completed, the adjustment state is fixed until it becomes auto again. .
[0083]
Next, driving of the ND filter 18 by the ND filter control unit 24 will be described. FIG. 9 is a flowchart showing the control processing procedure of the ND filter. This processing program is stored in the ROM 32 in the system control unit 22 and executed by the CPU 31.
[0084]
First, the key operation state of the ND on / off key 20 is determined (step S351), and if it is turned on, it is determined whether or not the ND filter 18 is turned on by the detection signal of the ND filter position detection unit 23. (Step S352).
[0085]
If the ON state is not detected, the ND filter 18 is driven in the ON direction under the control of the ND filter driving unit 19 (step S353), and an ND filter operating flag indicating that the ND filter 18 is operating is set. Set (step S354). Thereafter, the process returns to step S351.
[0086]
On the other hand, when the ND on / off key 20 is turned off in step S351, it is determined whether or not the ND filter 18 is turned off by the detection signal of the ND filter position detection unit 20 (step S355). If it is not detected that the switch is in the OFF state, the ND filter 18 is driven in the OFF direction under the control of the ND filter drive unit 19 (step S356), and the process proceeds to step S354.
[0087]
On the other hand, if it is detected in step S352 that the ND filter 18 is turned on, or if it is detected that the ND filter 18 is turned off in step S355, the ND filter driver 19 controls the ND filter. The filter 18 is stopped (step S357), and the ND filter operating flag is cleared (step S358). Thereafter, the process returns to step S351, and the same process is repeated.
[0088]
Next, the white balance adjustment of the video signal processing unit 16 by the white balance control unit 21 will be described. FIG. 10 is a flowchart showing the white balance adjustment processing procedure. This processing program is stored in the ROM 32 in the system control unit 22 and is executed by the CPU 31.
[0089]
First, it is determined whether or not reading of color information for each field related to a video signal, which is information necessary for white balance adjustment, from the video signal processing unit 16 is completed (step S381). If the reading of the color information has been completed, the key operating state of the WB auto / set key 25 is determined (step S382). When the auto mode is operated, the white balance adjustment control data for the auto mode is calculated. In step S383, the white balance adjustment control data is output to the video signal processing unit 16 (step S384), and the white balance adjustment control data is backed up (step S385).
[0090]
On the other hand, if the WB auto / set key 25 is not operated to the auto mode in step S382, it is determined whether the ND filter control unit 21 sets / clears the flag during the ND filter operation (step S386). If clear, it is determined whether or not the white balance is properly adjusted and the adjustment operation is completed (step S387). If not, calculation of white balance adjustment control data for the set mode is performed ( The process proceeds to step S388) and step S384, and the above-described steps S384 and S385 are performed.
[0091]
On the other hand, if the flag during ND filter operation is not cleared in step S386, or if the adjustment operation is completed in step S387, the white balance adjustment control data backed up in step S385 is read (step S389), and again. As white balance adjustment control data, the process proceeds to step S384, and the above-described steps S384 and S385 are performed. After the process of step S385, the process returns to step S381 and the same process is repeated.
[0092]
Although not described in FIG. 10, white balance at the time of power-on of the imaging apparatus is controlled by predetermined initial control data, and the initial control data is backed up.
[0093]
As described above, the white balance adjustment operation is stopped during the period in which the ND filter is operating in the direction in which the ND filter is inserted on the optical axis or in the direction in which the ND filter is extracted from the optical axis. It is held at the value before the start of operation in each direction.
[0094]
Although description is omitted in the third embodiment, correction of white balance deviation by the ND filter is appropriately performed before the process of step S384. Further, in the process of step S386, the control data output in step S384 only needs to be finally held during the operation period of the ND filter, and the processing order is not limited.
[0095]
In the third embodiment, the white balance adjustment operation stops during the ND filter operation period only when the white balance adjustment mode is set. The present invention is applicable.
[0096]
Furthermore, in the third embodiment, the control for inserting and removing the ND filter on the optical axis is based on the operation of the ND on / off key 24 by the operator. Depending on the amount of light of the imaged subject, the insertion and removal of the ND filter may be automatically controlled.
[0097]
[Fourth Embodiment]
Since the configuration of the imaging apparatus in the fourth embodiment is the same as that of the third embodiment, description thereof is omitted.
[0098]
The white balance adjustment of the video signal processing unit 16 by the white balance control unit 21 in the fourth embodiment will be described. FIG. 11 is a flowchart showing a white balance adjustment processing procedure in the fourth embodiment. This processing program is stored in the ROM 32 in the system control unit 22 and is executed by the CPU 31.
[0099]
First, it is determined whether or not reading of color information for each field related to a video signal, which is information necessary for white balance adjustment, from the video signal processing unit 16 is completed (step S401).
[0100]
If the color information has not been read, the process of step S401 is repeated again. If the reading of the color information has been completed, the key operating state of the WB auto / set key 25 is determined (step S402).
[0101]
When the WB auto / set key 25 is operated to auto, white balance adjustment control data for auto mode is calculated (step S403), and white balance indicating that white balance is being adjusted in set mode. The in-adjustment flag is cleared (step S404), white balance adjustment control data is output to the video signal processing unit 16 (step S405), and the white balance adjustment control data is backed up (step S406).
[0102]
On the other hand, if the WB auto / set key 25 is not operated to auto in step S402, it is determined whether or not the white balance is properly adjusted and the adjustment operation is finished (step S407). If the adjustment operation has not been completed, white balance adjustment control data for the set mode is calculated (step S408), a white balance adjustment flag is set (step S409), and the process proceeds to step S405. Steps S405 and S406 are performed.
[0103]
On the other hand, if the adjustment operation has been completed in step S407, the white balance adjustment control data backed up in step S406 is read out again as white balance adjustment control data (step S410), and the white balance adjustment in progress flag is cleared (step S410). S411), the process proceeds to step S405, and the above-described steps S405 and S406 are performed.
[0104]
After the process of step S406, the process returns to the process of step S401, and the same process is repeated. Although not described in FIG. 11, white balance at the time of power-on of the image pickup apparatus is controlled by predetermined initial control data, and the initial control data is backed up.
[0105]
Next, driving of the ND filter 18 by the ND filter control unit 24 will be described. FIG. 12 is a flowchart showing a control processing procedure of the ND filter. This processing program is stored in the ROM 32 in the system control unit 22 and is executed by the CPU 31.
[0106]
First, it is determined whether or not the white balance adjusting flag is set / cleared by the white balance control unit 22 (step S501). If clear, the key operation state of the ND on / off key 24 is discriminated (step S502). If it is turned on, whether or not the ND filter 18 is turned on by the detection signal of the ND filter position detection unit 23. Is determined (step S503).
[0107]
If it is not detected that the on state is detected, the ND filter 18 is driven in the on direction under the control of the ND filter driving unit 19 (step S504).
[0108]
On the other hand, if the ND on / off key 20 is not turned on in step S502, it is determined whether or not the ND filter 18 is turned off by the detection signal of the ND filter position detector 23 (step S505), and the ND filter 18 is turned off. If it is not detected, the ND filter 18 is driven in the OFF direction under the control of the ND filter driving unit 19 (step S506).
[0109]
On the other hand, if the white balance adjusting flag is not cleared in step S501, it is detected that the ND filter 18 is turned on in step S503, or the ND filter 18 is turned off in step S505. If it is, the ND filter 18 is stopped under the control of the ND filter driving unit 19 (step S507). After the process of step S504, S506, or S507, the process returns to step S501 and the same process is repeated.
[0110]
As described above, during the white balance adjustment period in the white balance set mode, the operation in the direction of inserting or removing from the optical axis of the ND filter is stopped, and the captured image is displayed during the period. The degree of influence of the ND filter is appropriately adjusted when the adjustment is started after the auto mode is changed to the set mode, and is maintained without change when the adjustment is completed.
[0111]
Although description is omitted in the fourth embodiment, correction of white balance deviation by the ND filter is appropriately performed before the process of step S405. In the process of step S501, the position of the ND filter 18 with respect to the optical axis in the processes of steps S504 and S506 only needs to be held during the white balance adjustment period, and the order of the processes is not particularly limited.
[0112]
Furthermore, in the fourth embodiment, the driving of the ND filter is stopped only when the white balance adjustment mode is set. However, even when the mode is auto, the adjustment execution operation is performed in the auto mode. The present invention is applicable as long as there is an adjustment stop operation.
[0113]
In the fourth embodiment, the control for inserting and removing the ND filter on the optical axis is performed based on the operation of the ND on / off key 24 by the operator. However, in the case of an imaging apparatus having a light amount detection unit. Depending on the amount of light of the detected or imaged subject, the insertion and removal of the ND filter may be automatically controlled.
[0114]
In each of the above embodiments, the case where an ND filter having an arbitrary transmittance in a wide wavelength band is used as the light amount adjustment filter for adjusting the incident light amount. However, the present invention is not limited to this, and a filter having various characteristics. An electro-optical element may be used as the light amount adjustment filter.
[0115]
Further, the present invention may be applied to a system constituted by a plurality of devices, or may be applied to an apparatus constituted by one device. Needless to say, the present invention can be applied to a case where the present invention is achieved by supplying a program to a system or apparatus. In this case, the system or apparatus can enjoy the effects of the present invention by reading the storage medium storing the program represented by the software for achieving the present invention into the system or apparatus.
[0116]
FIG. 13 is a diagram showing a memory map of the ROM 32 as a storage medium. In the ROM 32, the white balance adjustment processing program module shown in the flowchart of FIG. 3, the ND filter control processing program module shown in the flowchart of FIG. 9, the white balance adjustment processing program module shown in the flowchart of FIG. 10, and the white shown in the flowchart of FIG. The balance adjustment processing program module, the ND filter control processing program module shown in the flowchart of FIG. 12, and the like are stored.
[0117]
The storage medium for supplying the program module is not limited to the ROM, and for example, a floppy disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a DVD, a magnetic tape, a nonvolatile memory card, or the like may be used. it can.
[0118]
【The invention's effect】
According to the present invention, the white balance adjustment of the video signal is performed when the light from the subject under various light sources passes through the ND filter due to the spectral characteristics of the ND filter, so that the ND filter is not inserted on the optical axis. The color reproducibility changes between (ND filter off) and the state inserted on the optical axis (ND filter on), and the control data when the white balance is properly adjusted between these states Even if a difference occurs, the white balance adjustment control range is changed by turning off the ND filter and turning on the ND filter so that the white balance adjustment control data is always within the optimum control range in each case of the ND filter. To be controlled.
[0119]
As a result, it is possible to always maintain a good color reproduction of a photographed image by realizing appropriate white balance adjustment without being affected by the state of the ND filter.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of an imaging apparatus according to a first embodiment.
2 is a block diagram showing an electrical configuration of a system control unit 22. FIG.
FIG. 3 is a flowchart showing a white balance adjustment processing procedure;
FIG. 4 is a diagram illustrating a control range of white balance adjustment.
FIG. 5 is a diagram illustrating another control range in white balance adjustment.
FIG. 6 is a diagram illustrating another control range in white balance adjustment.
FIG. 7 is a block diagram illustrating a configuration of an imaging apparatus according to a second embodiment.
FIG. 8 is a block diagram illustrating a configuration of an imaging apparatus according to a third embodiment.
FIG. 9 is a flowchart showing an ND filter control processing procedure;
FIG. 10 is a flowchart illustrating a white balance adjustment processing procedure.
FIG. 11 is a flowchart illustrating a white balance adjustment processing procedure in the fourth embodiment.
FIG. 12 is a flowchart showing an ND filter control processing procedure;
FIG. 13 is a diagram showing a memory map of a ROM 32 as a storage medium.
FIG. 14 is a diagram illustrating white movement due to a color temperature change on a vector scope;
FIG. 15 is a diagram illustrating a control range of white balance adjustment.
FIG. 16 is a diagram illustrating a change in ND filter insertion timing and WB shift amount;
[Explanation of symbols]
13 Image sensor
16 Video signal processor
18 ND filter
19 ND filter driver
20 ND ON / OFF key
21 White balance control unit
22 System controller
23 ND filter position detector
24 ND filter control unit
25 WB Auto / Set key
31 CPU
32 ROM

Claims (7)

In an imaging apparatus that converts an optical signal from a subject incident through a lens into an electrical signal by an imaging device, and performs signal processing on the converted electrical signal to generate a video signal.
A light amount adjustment filter for adjusting the amount of incident light from the lens;
A light amount adjusting filter driving means for driving the light amount adjusting filter in a direction in which incident light from the lens is inserted into a position on the optical axis reaching the image sensor or a direction in which the light is adjusted from a position on the optical axis;
White balance adjustment control means for adjusting the white balance of the generated video signal,
The white balance adjustment control means includes:
White balance adjustment control data for adjusting the white balance is generated, a white balance adjustment control range for limiting the value that can be taken by the generated white balance adjustment control data is provided, and the light amount adjustment filter includes the light if inserted in a position on the axis, an imaging apparatus characterized by changing the white balance adjustment control range.   The imaging apparatus according to claim 1, further comprising: a light amount adjustment filter position detection unit configured to detect a position of the light amount adjustment filter with respect to the optical axis as information regarding the position of the light amount adjustment filter.   2. The image pickup apparatus according to claim 1, wherein the information on the position of the light amount adjustment filter is information on a driving state of the light amount adjustment filter driving unit.   2. The imaging apparatus according to claim 1, wherein the information regarding the position of the light amount adjustment filter is a state of a key operated by an operator to operate the light amount adjustment filter driving unit. And characterized by properly changing the white balance adjustment control range gain of a plurality of colors is based on how the moving of information in accordance with the light amount adjustment filter when white balance adjustment is performed under a plurality of light sources the imaging apparatus according to any one of claims 1 to 4. In a white balance adjustment method of an imaging apparatus that converts an optical signal from a subject incident through a lens into an electrical signal by an imaging device and performs signal processing on the converted electrical signal to generate a video signal.
A step of driving a light amount adjustment filter that adjusts the amount of incident light from the lens in a direction in which incident light from the lens is inserted into a position on the optical axis reaching the image sensor, or a direction in which the light is removed from the position on the optical axis When,
Generating white balance adjustment control data for adjusting white balance of the generated video signal;
And a step of changing a white balance adjustment control range that limits a value that can be taken by the generated white balance adjustment control data when the light amount adjustment filter is inserted at a position on the optical axis. A white balance adjustment method for the imaging apparatus. The generation is performed by a computer that controls an imaging device that converts an optical signal from a subject incident through a lens into an electrical signal by an imaging device, and performs signal processing on the converted electrical signal to generate a video signal. In a storage medium storing a program for adjusting the white balance of a video signal to be recorded,
The program is
A procedure for driving a light amount adjustment filter that adjusts the amount of incident light from the lens in a direction in which incident light from the lens is inserted into a position on the optical axis reaching the image sensor, or a direction in which the light is removed from the position on the optical axis When,
Generating white balance adjustment control data for adjusting white balance of the generated video signal;
And a procedure for changing a white balance adjustment control range that limits a value that can be taken by the generated white balance adjustment control data when the light amount adjustment filter is inserted at a position on the optical axis. A storage medium.

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