JP2754001B2 - Video camera - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a spectral distribution characteristic of a white balance color sensor such as a color video camera.

[Conventional technology]

2. Description of the Related Art Conventionally, in a color sensor (hereinafter, referred to as a white balance sensor) having a color separation function for correcting a color temperature of an external photometric light source light such as a color video camera, a primary color red used for an image sensor of the camera is used. , Green, and blue (hereinafter, referred to as R, G, B) color sensors having spectral distribution characteristics substantially equal to the spectral distribution characteristics of respective color separation filters (hereinafter, referred to as color filters) have been used.

[Problems to be solved by the invention]

However, in the above-described conventional configuration, the spectral distribution characteristics of each color filter used in the image sensor are not good, or the relationship between the installation location of each white balance sensor in a video camera and the light receiving area. In the case where the sensitivity is deteriorated due to, for example, the color temperature detection / discrimination of the light source light becomes impossible or improper, and there is a problem that a proper white balance correction may not be obtained.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems in the conventional color video camera, and means for detecting a color temperature change of light source light with high sensitivity without complicating the apparatus. The purpose is to provide.

[Means for solving the problem]

For this reason, in the present invention, in each color spectral distribution characteristic of the white balance sensor, the half width is smaller than the spectral distribution characteristic of each color filter for the image pickup device of the camera, or each color peak wavelength of the same distribution characteristic is used. For example, in the case of the R (red) sensor, the peak of the spectral distribution curve of the R channel of the image sensor is shifted to the longer wavelength side, and in the case of the B (blue) sensor, the peak of each color of the white balance sensor is shifted. The object is achieved by setting the wavelength interval wide.

[Action]

By employing a white balance sensor having the above-described spectral distribution characteristics of each color, a change in the color temperature of the light source light can be detected with high sensitivity without complicating the apparatus, and appropriate white balance correction can be performed. .

〔Example〕

 Hereinafter, the present invention will be described based on examples.

FIG. 3 shows a configuration block diagram of a color video camera to which the present invention can be applied.

(Configuration) In the figure, reference numeral 1 denotes an image sensor of a color video camera;
Is a processing circuit for each of the primary color signals R, G, B, 3 is an encoder, and 4 is a video signal. 5 is a white balance sensor, each of the white balance signal WB _R, WB _G, WB _B
And sends it to a microcomputer (hereinafter abbreviated as a microcomputer) 6.

(Operation) Hereinafter, the operation will be described with reference to FIG.

The optical image of the subject B formed by a lens (not shown) is photoelectrically converted by the image pickup device 1 and R, G, B
The signal is input to the signal processing circuit 2 as a color signal.
The signals are output to the encoder 3 as the respective color difference signals RY and BY.

On the other hand, the light source light LR input to the white balance sensor 5
Is outputted as two white balance signal values of WB _R and WB _B, converted A / D (analog / digital) is input to the microcomputer 6. The microcomputer 6 stores each signal WB in advance.
_R, WB _G, and a conversion table for outputting the gain G _B in the R channel gain G _R and B channel are stored as input WB _B, each gain G _R of the signal processing circuit 2, to adjust the G _B It is configured to take a white balance.

(Operation) On the other hand, the solid line in FIG. 1 shows an example of a spectral distribution characteristic represented by a wavelength versus transmittance curve of each of the R, G, and B color filters of the image sensor. FIG. 9 shows each spectral distribution characteristic curve of the white balance sensor 5 according to the present embodiment in which each half width of the curve is reduced.

For example, with respect to the reference light source light (LS) as shown by the solid line in the example of the wavelength vs. spectral distribution characteristic of the light source light in FIG. 4, the characteristic such that the actual light source light (LR) is shown by a broken line. If it does, the actual light source light LR is brighter in the longer wavelength range and darker in the lower wavelength range, compared to the reference light LS.
That is, LR is slightly cyan to bluish than LS. Here, the degree of bluishness varies depending on the spectral distribution characteristics of the white balance sensor 5, and a sensor having a distribution characteristic indicated by a dashed line rather than a sensor having a spectral distribution characteristic indicated by a solid line in FIG. Detects a larger amount of blueness. In other words, this indicates that the color balance is more sensitive to the deviation. Therefore, it is possible to sensitively detect the actual color temperature of the light source light LR even in a situation where it is difficult to detect the color balance such as under low illuminance.

The same effect can be realized by a white balance sensor having a spectral distribution characteristic as shown by a broken line in FIG. 2 in another example of FIG. That is, in this embodiment, each peak wavelength of the spectral distribution curve of the R sensor and the B sensor is
By shifting to the long wavelength side and short wavelength side respectively,
The peak wavelength interval of each color of the white balance sensor has a spectral distribution characteristic set wider than that of the distribution characteristic of each color filter of the image sensor.

(Other Embodiments) In the above embodiments, the primary color (R, G, B) processing type video camera has been described. However, the present invention is not limited to this. For example, cyan Cy, green G, yellow Ye
The principle of the present invention can be applied to an image sensor having a complementary color configuration. FIG. 5 shows an example of spectral distribution characteristics in the case of a complementary color filter. In this case, the R, G, and B signals in FIG. 3 are generated by subtraction of R = Ye−GB = Cy−G.

〔The invention's effect〕

As described above, according to the present invention, a change in the color temperature of the light source light can be detected with high sensitivity without complicating the video camera device, and appropriate white balance correction can be performed.

[Brief description of the drawings]

FIG. 1 is an example of a spectral distribution characteristic diagram of white balance of the present invention, FIG. 2 is another example of a spectral distribution characteristic diagram of white balance of the present invention, and FIG. 3 is a color video camera to which the present invention can be applied. FIG. 4 is an example of the spectral distribution characteristic of the light source light, and FIG. 5 is an example of the spectral distribution characteristic of the complementary color filter. 1 ... Image sensor 5 ... White balance sensor (color sensor) LR ... Light source light

Claims (1)

(57) [Claims] 1. A video camera for correcting the color temperature of light from a light source using a color sensor having a color separation function in addition to an image sensor, wherein each half-value width of each color spectral distribution characteristic of the color sensor is determined by the image sensor. The color separation filter may have a characteristic that is smaller than that of each color spectral distribution characteristic or that each color spectral distribution characteristic of the color sensor has a wider wavelength interval of each color peak than that of the color separation filter. A video camera characterized by the settings.