KR100191313B1 - Method and apparatus for displaying position of the color temperature filter of a camera - Google Patents

Abstract

The present invention relates to a color temperature filter position display apparatus and a method of displaying a color temperature filter position of a camera that provides a user with convenience in operating a color temperature filter by informing a user of a color temperature filter position most suitable for a current light source to a camera equipped with a color temperature filter. . The present invention prestores information on light source characteristics and attenuation characteristics of a color temperature filter in an image capturing state, and calculates the relative ratio (G / B) between two color signals calculated from an average value of green (G) and blue (B) signals among the image signals. The color temperature filter most suitable for the current image pickup state is determined in comparison with. Thus, the determined color temperature filter is displayed on the electronic viewfinder so that a more accurate position change can occur rather than the color temperature filter position change by the user's judgment.

Description

Color temperature filter position indicator of camera and its method

1 is a block diagram showing a color temperature filter position display apparatus of a camera to which the present invention is applied.

2 is a control flow chart showing a color temperature filter position display method of the present invention.

* Explanation of symbols for main parts of the drawings

12 color temperature filter 13 CCD image pickup device

14: signal processor 15,16: variable gain amplifier

17: matrix unit 18: data detection unit

19: white balancing circuit 20: comparison judgment

21: Electronic viewfinder (EVF)

The present invention relates to a change in position of a color temperature filter of a camera, and more particularly, to a color temperature filter position display apparatus and a method of providing a color temperature filter operation by informing a user of a suitable color temperature filter position according to an imaging state. will be.

The most ideal thing for a camera is to recognize the subject as humans perceive it. While the human eye is not aware, the subject focuses very quickly and accurately, and the whites feel the same white in light sources with a high color temperature, such as fluorescent lamps, or in low light temperatures, such as incandescent lamps. On the other hand, due to mechanical, electrical and optical limitations, it is difficult for the camera to accurately focus on the subject or to faithfully reflect the color of the subject. In particular, since it does not properly reflect the color of the object is a very big problem has been proposed to solve this problem.

One of the above methods is white balance (AWB) function, the basic principle is as follows. A light source with a higher color temperature than a standard light source exhibits a blue sign because the energy near the blue wavelength is high, and a light source with a low color temperature shows a red sign. Therefore, when an object that appears to be white (R = G = B) in a standard light source is picked up by a light source having a high color temperature, the blue portion B is relatively stronger than the rest, and thus appears blue. In addition, when the standard white object is imaged under a light source having a low color temperature, the red component (R) is relatively large, so that the white color is relatively red, and thus white color cannot be properly expressed. Therefore, the gain of the amplifier is adjusted so that the ratio of red (R), green (G), and blue (B) is 1: 1: 1 regardless of the type of light source in the state of photographing a standard white object. White balancing is a similar compliance feature.

In the broadcast camera, the infrared blocking filter or the color temperature filter is used to remove components that interfere with color signal processing or to make unnecessary components suitable for color signal processing before white balancing. While the infrared cut filter removes unnecessary optical signals, the color temperature filter modifies the spectral power density of the incident light, that is, the distribution of energy at each frequency. This is to optically preprocess that the imaging of the camera does not adequately adapt to changes in the light source. To this end, when the color temperature of the light source is high, the color temperature filter increases the transmittance for the red component compared to the blue component so that the white can still be recognized as white even if the light source is changed.

When a relatively fixed light source such as a studio is used, the distribution of spectral power density according to the color temperature of the light source can be expected to some extent. Therefore, in case of broadcast camera, color temperature filter for 5600K and 3200K, which are mainly used in studio, is pre-installed, and the transmittance is controlled by changing the type of filter according to the imaging state. B) After the ratio is adjusted, white balancing is performed. Particularly, since the control range for white balancing is preferably narrow, replacing the color temperature filter according to the state of the light source can maintain the optimum state without the user's consciousness, which is preferable for accurate control.

Conventionally, since a mechanical switch or an electric button is installed in the camera body to replace the color temperature filter, the user has to manually select the filter most suitable for the current light source by operating the switch or the button.

However, this method has a troublesome problem, of course, can not be accurately controlled because the user has to change the color temperature filter at his or her own judgment when the light source is changed.

Accordingly, an object of the present invention is to provide a convenience to the user's color temperature filter operation by informing the user by displaying the position of the color temperature filter most suitable for the current light source using a color signal to solve the above problems. A color temperature filter position display apparatus and a method thereof of a camera are provided.

The color temperature filter position display device of the camera according to the present invention for achieving the above object is adjusted by using the color temperature filter of the component of the incident light, using the color signal of red (R), green (G), blue (B) white In a balanced imaging system, a data detector for detecting an average value of each color signal and a relative ratio of an average value of another color signal to an average value of a green (G) signal among the detected average values of each color signal are detected. And a comparison determination unit for comparing the stored comparison value and determining the filter position of the color temperature filter to be replaced according to the comparison result, and an electronic viewfinder for displaying the filter position of the color temperature filter to be replaced.

In addition, the color temperature filter position display method of the camera according to the present invention for achieving the above object is to adjust the components of the incident tube with the color temperature filter, the average value of the red (R), green (G), blue (B) color signal In a control method of an imaging system that balances white balance according to (Ravg, Gavg, Bavg), the ratio of the average value of two color signals among the average values of the color signals after making the filter position set based on the color temperature filter before the white balance is adjusted ( In the first step of comparing Gavg / Bavg) with the first comparison value, and in the comparison of the first step, if the average color ratio Gavg / Bavg is greater than the first comparison value, the current light source is set as a reference. In a comparison between the second step and the first step of displaying the screen to maintain the current color temperature filter position by determining that the color temperature filter is close to the standard light source, if the average value ratio of two color signals Gavg / Bavg is smaller than the first comparison value, 2 Comparative value And a third step of determining a filter position most suitable for the color temperature of the current light source according to the comparison result and displaying the screen to change the current color temperature filter position to the position.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram showing a color temperature filter position display apparatus of a camera to which the present invention is applied. As shown, the camera of the present invention includes a color temperature filter 12 which makes the transmittance of a specific component among the optical signals incident through the lens 11 relatively large, thereby making it suitable for color signal processing. Incident light that has passed through the color temperature filter 12 is applied to the CCD image pickup device 13, and the CCD image pickup device 13 converts the intensity of the input optical signal into an electric video signal and outputs it. A signal processor 14 is connected to the output terminal of the CCD imager 13 to easily amplify the weak input signal and to remove the unnecessary components or signals above a prescribed level, thereby appropriately processing the video signal waveform. The red (R), green (G), and blue (B) image signals output from the signal processing unit 14 are applied to the data detection unit 18 and to the matrix unit 17, and are applied to the luminance signal Y and the color difference. The signal RY is converted to BY. Here, the red (R) and blue (B) video signals pass through the variable gain amplifiers 15 and 16.

The data detector 18 detects average values Ravg, Gave, and Bavg of the color signals R, G, and B, outputs the average values Ravg, Gave, and Bavg to the white balancing circuit 19, and outputs green (G) values. ), The average value (Gave, Bavg) of the blue (B) signal is output to the comparison determination unit 20. The white balancing circuit 19 varies the gain of the variable gain amplifiers 15 and 16 according to the input average values Ravg, Gave, and Bavg to red (R) and green (G) images of the standard white object. The ratio of blue (B) is made equal. The comparison determination unit 20 extracts a relative ratio between the input average values Gavg and Bavg, and compares them with previously stored comparison values. The comparison determination unit 20 determines the position of the most suitable color temperature filter 12 of the current light source according to the comparison result and displays it on the electronic view finder (EVF) 21. Here, the comparison values previously stored in the comparison determination unit 20 are as shown in Table 1 below, which is determined from the spectral distribution characteristics of the light source and the attenuation characteristics of the color temperature filter.

Here, when the spectral distribution characteristics of the light source are set to a light source A (32000K) having a low color temperature, a light source C (6300K) having a high color temperature, and a light source B (4300K) having a medium level, A having a low color temperature is blue (B). C) component is small, red (R) component is high, and color temperature is high C, on the contrary, red (R) component is small and blue (B) component is large. Therefore, the components of red (R), green (G), and blue (B) also differ according to each light source. Select the ratio of green (G) and blue (B) components as the parameter to distinguish the light source. If the ratio (G / B) of the blue (B) component to the green (G) of each light source is Sa, Sb, and Sc, the relationship between them is SaSbSc. The characteristics of the color temperature filter also have opposite characteristics in accordance with the spectral distribution characteristics of each light source. For example, the color temperature filter A attenuates the red (R) component relatively more than the blue (B) component to optically correct an imbalance between the red (R), green (G), and blue (B) components of the light source A. Let's do it. On the other hand, in order to detect the light source, it is necessary to fix the position of the color temperature filter. Here, the color temperature filter A for 3200K, which is generally used as a studio standard, is set as a reference. Thus, the comparison determination unit 20 sets the green (G) signal of the reference color temperature filter A set in the relative ratios (Sa, Sb, Sc) of the blue (B) signal to the green (G) signal according to the type of light source. The values Da, Db, and Dc multiplied by the relative ratio Ca of the blue (B) signal with respect to are previously stored as comparison values.

2 is a control flowchart showing the color temperature filter position display method of the present invention. In this case, white balance is automatically adjusted by pressing the external button while the white object is photographed in one-shot mode, and the appropriate filter is selected until the white balance is adjusted after the button is pressed. Assume that it is done.

First, the comparison unit 20 determines whether the external button is pressed to match the white balancing circuit (step 101), and when the button is pressed, A sets the position of the color temperature filter 12 as a reference through the existing servo drive. Move to the position of the filter and set the gain of the variable gain amplifiers 15, 16 to 1 (step 102). In this state, the relative ratio Gavg / Bavg between the average values Gave and Bavg of the green and blue signals obtained through the data detector 18 is detected, and the internal storage place D1 is not shown. In step 103). Then, the stored value of the internal memory location D1 and the previously stored Table 1 are the average values of the comparison values Da and Db of the light source A and the light source B among the comparison values Da, Db and Dc [(Da). + Db) / 2] are compared (step 104), and if the stored value is larger than the average value, it is determined that the current light source is A and the screen is displayed to maintain the current color temperature filter A (step 105). If the stored value is smaller than the average value, the stored value and the average value [(Db + Dc) / 2] of the comparison values Db and Dc for the light source B and the light source C are compared (step 106). It is determined that the current light source is close to B, and the screen is displayed to change the current color temperature filter position to B (step 107). If the stored value is smaller than the average value, it is determined that the current light source is close to C, and the screen is displayed to change the current color temperature filter position to C (step 108).

By performing the above steps, the user is informed of the location of the appropriate color temperature filter for the current light source, and the user changes the color temperature filter accordingly. Then, the gain of the variable gain amplifiers 15 and 16 is varied so that the red (R), green (G), and blue (B) components are 1: 1: 1 by performing white balancing.

As described above, the present invention relates to a color temperature filter position display device and a method of the camera, and to compare each color signal passing through a color temperature filter set as a reference, compared to the conventional manual operation of a color temperature filter suitable for a light source at the user's discretion. By detecting the average value and comparing the relative ratio between the two color signal average values with previously stored comparison values, the appropriate color temperature filter position is displayed on the screen to provide convenience for the user to operate the color temperature filter and to provide more accurate control. Has an effect.

Claims (9)

In an imaging system in which incident light is controlled using a color temperature filter and white balance is adjusted using color signals of red (R), green (G), and blue (B), a color temperature filter set as a reference before white balancing is set. A data detector for detecting an average value of each of the color signals obtained through the apparatus; The relative ratio of the average value of the other color signal to the average value of the green (G) color signal among the average values of the detected color signals is detected and compared with the previously stored comparison value, and the filter position of the color temperature filter to be replaced according to the comparison result is determined. Comparing judging unit; And an electronic viewfinder for displaying the filter position of the color temperature filter to be replaced. The method of claim 1, wherein when the color temperature filter set as the reference is a color temperature filter for a standard light source of the studio, the comparison determining unit is configured to generate a blue (B) value for the average value of the green (G) signal among the average values of the detected color signals. The color temperature filter position display device of a camera, characterized by detecting a relative ratio of an average value of a color signal. The apparatus of claim 1, wherein the pre-stored comparison value of the comparison determination unit is determined according to the spectral distribution characteristic of the light source and the attenuation characteristic of the color temperature filter. The green (G) color of the reference color temperature filter according to claim 2 or 3, wherein the comparison unit determines the relative ratios of the blue (B) signal to the green (G) signal according to the type of light source. The color temperature filter position display device of the camera, characterized in that the values obtained by multiplying the relative ratio of the blue (B) color signal to the signal as a comparison value. The apparatus of claim 4, wherein the comparison determination unit determines the position of the color temperature filter by comparing the magnitude of the average value and the average value between the comparison values. A control method of an imaging system in which a component of incident light is adjusted with a color temperature filter and white balance is adjusted according to average values (Rvg, Gavg, Bavg) of red (R), green (G), and blue (B) signals. A first step of making the filter position set based on the color temperature filter before balancing the balance, and comparing the ratio (Gavg / Bavg) of the average value of the two color signals among the average values of the color signals with the first comparison value; In the comparison of the first step, if the average value ratio (Gavg / Bavg) of the two color signals is greater than the first comparison value, it is determined that the current light source is close to the standard light source of the color temperature filter set as a reference to maintain the current color temperature filter position. A second step of displaying the screen; In the comparison of the first step, if the average color value ratio (Gavg / Bavg) of the two color signals is smaller than the first comparison value, the second comparison value is compared with the second comparison value, and the filter position most suitable for the color temperature of the current light source is determined according to the comparison result. And displaying the screen to change the current color temperature filter position to the position. The color comparison filter of claim 6, wherein the first comparison value and the second comparison value are based on a ratio (Sa, Sb, Sc) of the green (G) component and the blue (B) component of each light source. Average value [(Da + Db) / 2] [(Db + Dc) between two of the values (Da, Db, Dc) multiplied by the ratio (Ca) of green (G) and blue (B) components obtained from the light source / 2] color temperature filter position display method of the camera, characterized in that. 8. The method of claim 7, wherein the first step comprises: a1 determining whether the external button is pressed to achieve white balancing; When the button is pressed, the color temperature filter for the light source having a low color temperature set as a reference regardless of the current filter type is placed in step b1: green (G) of the color signal obtained through the color temperature filter located in the step b1. C1, detecting and storing a ratio (Gavg / Bavg) of an average value of the green and blue (B) color signals; And comparing the ratio (Gavg / Bavg) of the average value of the green (G) and blue (B) color signals stored in step c1 with the first comparison value [(Da + Db) / 2]. Color temperature filter position display method of the camera, characterized in that made. The method of claim 8, wherein the third step is a ratio (Gavg / Bavg) of the average value of the green (G) and blue (B) color signals stored in step c1 to the second comparison value [(Db + Dc) / A second step of determining that the current light source is close to the light source of the color temperature filter having a medium color temperature, and displaying the screen to change the current color temperature filter position to the filter position; And when the ratio (Gavg / Bavg) of the average value of the green (G) and blue (B) color signals stored in the step c1 is smaller than the second comparison value [(Db + Dc) / 2], the current light source has a color temperature. And b3, determining that the color temperature filter position is close to the light source of the high color temperature filter, and displaying the screen to change the current color temperature filter position to the filter position.