JPH10108205A - Device for correcting white balance and its method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate an operation at the time of adjusting white balance by changing an electric gain value in accordance with the setting value of white balance and automatically changing the position of a color temp. correcting filter interlocking it with the gain value. SOLUTION: When white balance setting is required, one of the several color temp. correcting filters which is suitable for a present illuminance is selected. Through this, inputted RGB signals are read from a memory 160 and amplified by an initially set gain value and, after that, the deviation of the respective signals in largeness is operated. The gain value of the RGB signal is adjusted through the use of the deviation value. After the completion of initial setting, a control part 140 recognizes a white balance channel and, then, reads the initial gain value applying to the changed channel and the position value of a color temp. correcting filter part 110 from the memory 160. After that, a driving signal is impressed on a deiving part 150 so as to change the position of the color temp. correcting filter 110. Then, the gain of the RGB signal is adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for adjusting the white balance of a video camera, and more particularly, to a color temperature correction control apparatus having a plurality of color temperature correction filters together with a white balance gain control unit, and an apparatus for such a device. It relates to a white balance correction method.

[0002]

2. Description of the Related Art Generally, in a video camera, as shown in FIG. 3, the sensitivities of R, G, and B signals change according to illumination. As a result, the magnitude of the photoelectrically converted signal changes depending on the wavelength.
The white balance must be adjusted using optical or electrical means so that the sensitivity of each wavelength signal is constant. What is white balance adjustment R, G, B
Is to adjust the optical or electrical gain so that the angle for each wavelength becomes constant so that a white object can be viewed as white.

In a conventional broadcast / business video camera requiring high image quality, the white balance adjustment technique first performs color correction by a color temperature correction filter corresponding to the color temperature of each illumination, and then reduces the photoelectric conversion gain. Control and perform precise correction. In such a system, a set of photoelectric conversion gain values corresponding to a plurality of color temperatures is stored in a memory, and the photoelectric conversion gain value selected by the white balance channel selection switch is used for white balance correction. Therefore, when the deviation of the illumination color temperature is large, such as indoors and outdoors, the color temperature correction filter should be selected in conjunction with the electrical white balance correction. In this case, the position of the color temperature correction filter must be manually adjusted separately from the selection of the photoelectric conversion gain value by the white balance channel selection switch, and thus there is an inconvenient operation.

[0004]

The technical problem to be solved by the present invention is to change the position of the color temperature correction filter together with the photoelectric conversion gain when the white balance channel selection switch is changed. A correction device and method are provided.

[0005]

According to the present invention, there is provided a color temperature correction filter control device for changing the white balance of a video camera, comprising a plurality of color temperature correction filters having different transmittances for each of R, G, and B wavelengths. An optical correction unit configured to move the position of the filter according to a filter control signal, a photoelectric conversion gain value of white balance determined by a color temperature of a subject in a white balance adjustment mode, and the selected color temperature correction filter When the position value of the color temperature correction filter is stored in an area corresponding to the set channel and the white balance setting channel is changed, the color temperature correction filter unit stores the position value of the color temperature correction filter stored in the memory. Includes a white balance control unit that generates a filter control signal for moving the filter. It is characterized in.

The color temperature correction filter control method according to the white balance change of the video camera according to the present invention is based on the position value of the color temperature correction filter in the white balance adjustment mode and the magnitudes of the electrical signals of R, G, B and each wavelength. A gain value for maintaining the same value is stored in a memory area corresponding to a predetermined channel, and a white balance adjustment value storing step is performed. It is repeatedly determined whether a currently set white balance channel value is changed. A step of changing a gain value for controlling the gain of an electrical signal of R, G, and B wavelengths of an input signal with a gain value corresponding to a channel changed at the time of change, and a color stored in a memory area corresponding to the changed channel; The position of the temperature correction filter is compared with the current position of the color temperature correction filter, and the position of the color temperature correction filter is compared with the color stored in the memory. Characterized in including a time correction filter position change step of changing the position of the filter.

[0007]

Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. As shown in FIG. 1, the apparatus for correcting white balance of a video camera according to the present invention includes lenses 100, 120, 130, 1
40, 150, 160 and 170. In the white balance adjustment according to the present embodiment, after the color temperature is roughly compensated while the position of the color temperature correction filter is manually changed temporarily, the gain of each of the R, G, and B signals is finely adjusted electrically. The white balance is obtained by controlling the magnitudes of the R, G, and B signals in the same manner, and the gain value is stored in a memory for use.

The color temperature correction filter section 110 is composed of a plurality of color temperature correction filters, and each color temperature correction filter is set to have a unique position value. Then, each color temperature correction filter sets the transmittance for each of the R, G, and B wavelengths differently. During the white balance adjustment period, one color temperature correction filter having a transmittance that enables the intensity of the optical signal for each wavelength to be optically corrected at a constant rate according to the color temperature is manually selected. . When executing the recording mode after the white balance adjustment is completed, if the shooting environment changes and the user selects the white balance of another channel stored in advance, the position value of the color temperature correction filter stored in the memory will be changed. The color temperature correction filter is changed by the corresponding drive voltage.

The photoelectric conversion unit 120 converts the optical signal that has passed through the selected color temperature correction filter into an electrical signal and outputs the electrical signal. The gain controller 130 adjusts the gain of the R, G, and B signals according to the gain value output from the controller 140. The memory 160 stores a plurality of color temperature correction filters corresponding to a plurality of white balance channels.
The initial gain values for the G and C signals and the optimized gain values are stored.

The control unit 140 reads the position and initial gain value of the color temperature correction filter from the memory in response to a channel selection signal from a white balance channel selection switch operated by the user, and applies a drive signal to the drive unit 150. Then, one correction filter is selected, and the initial gain value is output to the gain control unit 130. Then, the magnitudes of the R, G, and C signals output from the gain control unit 130 are compared to calculate a gain value that makes the magnitudes of the R, G, and B signals of the gain-controlled signals the same. If it is determined that the white balance has been achieved, the control unit 140 stores the gain value at this time as an optimal gain value in the white balance memory 160 and uses it for the subsequent gain control. On the other hand, the control unit 140 continuously checks whether the optimum gain value needs to be changed even during shooting.

The driving section 150 drives the color temperature correction filter section 110 according to the drive signal to change the position of the color temperature correction filter. If a change in the color temperature of the subject is severely generated during recording, the white balance value must be changed. When the user changes to the color temperature correction filter of another channel with this, the initial gain control value of the changed channel and the position value of the color temperature correction filter are read from the memory. Then, a filter third-degree signal for changing the color temperature correction filter read from the memory is applied to the drive unit 150. The initial gain value is output to the gain control unit 130. Position detector 1
Reference numeral 70 denotes a position value of the color temperature correction filter that allows an optical signal input from among the plurality of color temperature correction filters of the color temperature correction filter unit 110 to pass, and outputs the position value to the control unit 140 so that the control unit 140 can use the current value. Make the filters inside clearly visible.

In accordance with the present invention, when the white balance selection switch is changed to change the white balance channel, the color temperature correction filter stored in the memory 160 is reset together with the electrical gain control value. The position also changes automatically in conjunction with it. Referring to FIG. 2, a method for controlling a color temperature correction filter according to a change in white balance of a video camera according to the present invention will be described below. The white balance adjustment method shown in FIG. 2 includes an initial stage setting stage (201-207) and an in-use adjustment stage (208-212).

First, in step 201, the user checks whether the mode is for setting a white balance value. That is, it is determined whether it is necessary to newly determine the position value of the color temperature correction filter of the white balance value and the gain values of the signals of the R, G, and B wavelengths in the environment in which the image is to be captured. If it is determined that the white balance must be set in step 201, one of the several color temperature correction filters that matches the current illuminance is selected using the channel selection switch. (Step 202).

In step 203, the R, G, and B signals input through the selected color temperature correction filter are amplified by the initially set gain values read from the memory, and then the magnitude deviation of each signal is calculated. I do. In operation 204, the gain values of the R, G, and B signals are adjusted using the calculated deviation values.
That is, when the deviation of RG has a positive value, the magnitude of the G signal is smaller than that of the R signal. Balance the signal. In this way, the magnitudes of the R and B signals are adjusted to control the gain values of the respective signals at which the magnitudes of the R, G, and B signals are the same.

Next, in step 205, it is checked whether the deviation of the magnitudes of the R, G, and B signals is smaller than a predetermined reference value and the white balance is achieved. If it is determined in step 205 that the white balance state has been achieved, the gain value for each of the R, G, and B signals is stored in the memory 160 after the white balance adjustment is completed, and this value is used for the time being ( 206 stage). This ends the initial setting mode. Thereafter, imaging is performed (2).
07 stage). Next, a method of changing the color temperature correction position due to sudden change in illuminance after setting the white balance or suddenly during use of the video camera without changing the white balance setting will be described. If the photographing condition changes and the color temperature adjustment filter is to be changed, the user issues a change command using the white balance channel selection key.

When the change key is input to the white balance channel (step 208), the control unit 140 recognizes the white balance channel indicated by the channel selection key, and then the control unit 140 determines the initial gain corresponding to the changed channel. After reading the value and the position value of the color temperature correction filter from the memory 160, a driving signal is applied to the driving unit 150 to change the position of the filter 110 (step 209).
In step 210, the gains of the R, G, and B signals are changed in order to achieve white balance in the same manner as in steps 203 and 204.

At this time, the user can change the position of the color temperature correction filter once or more. Therefore, 2
In operation 11, the control unit 140 checks whether a change command is input from the channel selection switch for a predetermined time. If the change command has not been input for the predetermined time, the white balance adjustment step is ended. However, when the change command is input again, the gain of the RGB signal is adjusted after the position of the filter is changed by the selection command (step 212). Therefore, when the white balance channel selection signal is input, the initial control gain values of the R, G, and B signals are read, and at the same time, the position value of the color temperature correction filter is automatically changed.

[0018]

As described above, according to the present invention, the electrical gain value changes according to the set value of the white balance, and the position of the color temperature correction filter is automatically changed in conjunction with the change. Thereby, the operation at the time of white balance adjustment can be easily performed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a white balance correction device for a video camera according to the present invention.

FIG. 2 is a flowchart of a white balance correction method according to the present invention.

FIG. 3 R, G,
The sensitivity to the B signal is shown.

[Explanation of symbols]

 110 color temperature correction filter section 120 photoelectric conversion section 130 gain control section 140 control section 150 drive section 160 memory 170 position detection section

Claims (3)

[Claims] 1. An optical correction system comprising a plurality of color temperature correction filters having different transmittances for respective wavelengths of R, G, and B, and for moving a position of the color temperature correction filter in accordance with a filter control signal. Unit, an initial gain value for a plurality of white balance channels determined by a color temperature, a position value of a color temperature correction filter, a memory for storing an optimal gain value, and a channel change signal for externally changing the white balance channel. When the voltage is applied, a filter control signal for driving the optical correction unit is generated based on the position value of the color temperature correction filter stored in the memory, and R, G, and B are calculated according to the initial gain value stored in the memory. After controlling the gain of the signal, calculating the optimal gain value and storing it in the memory, the gain of the R, G, B signals is used according to the optimal gain value. White balance correction apparatus of a video camera, characterized in contain the white balance control unit for controlling. 2. The color temperature correction filter section comprising a plurality of color temperature correction filters having different transmittances for each of R, G, and B wavelengths, and a plurality of colors of the color temperature correction filter section. A position detection unit for detecting a position value of a color temperature correction filter that allows an input optical signal of the temperature correction filter to pass therethrough; and a driving unit for moving the color temperature correction filter in accordance with the filter control signal. The color temperature correction filter control device according to claim 1, wherein the color temperature correction filter control device changes the white balance of the video camera. 3. A method for storing initial gain values for the position values R, G, and B signals of a plurality of color temperature correction filters corresponding to a plurality of white balance channels in a memory, and a currently set white balance channel value. And confirming whether the values should be changed, changing the color temperature correction filter at the time of the change, controlling the gains of the R, G, and B signals with the gain value corresponding to the changed channel, and calculating the optimum gain value. Controlling a gain of R, G, B signals according to the optimum gain value. 4. A method of controlling a color temperature correction filter according to a change in white balance of a video camera.