JPH0775113A - Video camera - Google Patents

Abstract

PURPOSE:To surely distinguish a light source and to exactly and speedily perform white balance adjustment by discriminating the light source while using only the infrared information and ON/OFF information. CONSTITUTION:Based on the infrared information (information concerning flicker) outputted from an infrared sensor 10 and flicker information outputted from a flicker detection circuit 1, at an AWB control circuit 24, it can be judged whether the light source is sun at fine or cloudy time, electric bulb such as a tungsten light or fluorescent lamp. The detection circuit 1 sends a frequency signal based on the power supply frequency of the light source contained in the infrared information outputted from the sensor 10 to the circuit 24 as flicker. The circuit 24 can immediately discriminate the classes of these three light sources corresponding to the combination of the presence/absence of infrared rays in the infrared information outputted from the sensor 10 and the presence/ absence of flicker information outputted from the circuit 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video camera for white balance control of color video signals.

[0002]

2. Description of the Related Art FIG. 3 is a basic block diagram of a video signal system of a conventional video camera.

As shown in FIG. 3, in a video signal system of a so-called video camera which is a VTR with a built-in camera, as shown in FIG. 3, a zoom system lens (not shown) advances and retreats according to a distance to the subject by taking in light from an object (not shown). The image pickup lens 11 that freely moves and outputs distance information (so-called zoom information) according to the movement distance to an auto white balance control circuit (AWB control circuit) 24 described later, and the light amount of light passing through the image pickup lens 11 The AWB control circuit 2 adjusts the aperture information according to the aperture value.
4, a diaphragm 12 for outputting to the image pickup device 4, an image sensor 13 which is composed of a CCD for photoelectrically converting the received optical image whose light amount is adjusted by the diaphragm 12, and noise of a line-sequential video signal output from the image sensor 13 is reduced. A CDS circuit 14, an AGC circuit 15 for always keeping the amplitude of the noise-reduced line-sequential video signal outputted from the CDS circuit 14,
A Y / C separation circuit 16 for band-dividing a line-sequential video signal output from the GC circuit 15 into a luminance (Y) signal and a color signal (C), and contour correction of the luminance signal output from the Y / C separation circuit 16. And a brightness signal processing circuit 1 for outputting a focus detection signal to an automatic focus control circuit 22 described later.
7. The primary color signals R and B obtained by separating the color signals output from the Y / C separation circuit 16 are output, and the color temperature information corresponding to the primary color signals R and B is output to the AWB control circuit 2
4 and a white balance control circuit (WB) for outputting the primary color signals R and B in a normal white balance state to which the primary color signals R and B output from the color signal separation circuit 18 are respectively supplied. CT
L circuit) 19, a color signal processing circuit 20 for generating color difference signals RY and BY based on the primary color signals R and B and the luminance signal output from the white balance control circuit 19, and this color signal processing circuit 20. An encoder circuit 21 for generating a carrier color signal based on the color difference signals R-Y and B-Y output from the image pickup lens 11, and an automatic focusing operation of the image pickup lens 11 by a focus detection signal output from the luminance signal processing circuit 17. Feedback control and the illuminance information (so-called low contrast information) of the captured image is AW
An automatic focus control circuit (AF circuit) 22 that outputs to the B control circuit 24, and color difference information obtained by integrating the color difference signals RY and BY output from the color signal processing circuit 20 described above is output to the AWB control circuit 24. Integrating circuit 2
3. An AW that outputs a white balance correction signal for adjusting the white balance gain to the color signal separation circuit 18 and the white balance control circuit 19 described above.
The B control circuit 24 includes an infrared sensor 10 that outputs infrared information for detecting infrared rays emitted from a light source that illuminates a subject to the AWB control circuit 24.

The luminance signal output from the luminance signal processing circuit 17 and the carrier color signal output from the encoder circuit 21 are frequency-multiplexed by a frequency multiplexing circuit (not shown) in the next stage, if necessary, to form a composite image. The signal is supplied to the input side of a recording system (not shown) of a VTR having a well-known configuration, where necessary recording signal processing is performed, and then recorded on a magnetic tape by a well-known recording method.

Now, the above-mentioned AWB control circuit 2
4 is capable of outputting a color signal having a proper white balance at all times from the encoder circuit 21 by switching and using two kinds of control modes, so-called a close mode and a preset mode, which will be described later, as needed. It is for doing.

First, in the close mode, when the entire imaged screen is white, mainly based on the color temperature information supplied from the color signal separation circuit 18 and the color difference information supplied from the integration circuit 23. , The encoder circuit 2 described above
1 so that there is no output of the color signal output from 1 (that is, the difference between the color difference signal R−Y and the color difference signal B−Y becomes “0”, and a normal white balance is achieved). Color signal separation circuit 18, white balance control circuit 19, color signal processing circuit 20, integration circuit 23, A
In a series of closed loops composed of the WB control circuit 24 and the color signal separation circuit 18, the AWB control circuit 24 performs sequential feedback control mainly based on the color difference information from the integration circuit 23 while performing the color signal separation circuit 18 and the white balance. In this mode, the white balance correction control signal is gradually output to the control circuit 19 to control the white balance gain of each of the primary color signals R and B.

Next, in the preset mode, indoor (I
Color temperature information of the primary color signals R and B emitted from various light sources that are frequently used for NDOOR photography and outdoor (OUTDOOR) photography (for example, indoors with electric lights, fluorescent lights,
The color temperature information of the primary color signals R and B emitted from the tungsten electric lamps, and the color temperature information of the primary color signals R and B emitted from the clear sky light and cloudy sky light, respectively, are shown in the AWB control circuit 24. The white balance correction control signals are output to the white balance control circuit 19 according to the light source of the subject by immediately outputting the white balance correction control signals based on the preset color temperature information. This is a mode in which each gain can be set.

Now, the white balance control operation for video shooting will be described. That is, the above-mentioned AWB control circuit 24 judges a total of six information contents of color difference information from the integrating circuit 23 and five pieces of information to be described later according to various information judgment procedures built therein, and closes according to the judgment result. The white balance is adjusted by switching the control mode between the mode and the preset mode.

Here, the above-mentioned six pieces of information are the following pieces of information (1) to (6). (1) Infrared information (information about infrared rays emitted from a light source) (2) Aperture value information (information about intensity of light received by the image sensor 13) (3) Distance information (so-called zoom information. Zoom system of the imaging lens 11) Information regarding the distance that the lens moves back and forth) (4) Illuminance information (so-called low contrast information).
(Information regarding brightness (contrast) of captured image) (5) Color temperature information (Information regarding each color temperature of primary color signals R and B forming the captured image) (6) Color difference information (Color difference signal RY, Information about BY) The AWB control circuit 24 described above determines the type of light source based on the “infrared information”, determines the light intensity of the subject based on the “aperture value information”, and determines the light intensity of the subject based on the “distance information”. If the focus distance is judged, and if this distance is greater than or less than a predetermined value, it is judged whether the subject is outdoors or indoors, and the brightness of the captured image is judged by "illuminance information". If the value is less than the value, it is determined that the subject is a single color, and each color temperature and color balance of the primary color signals R and B forming the image captured by the “color temperature information” is not affected by the brightness. Comparing determined and quasi color temperature. As a result, the AWB control circuit 24 selects either the close mode or the preset mode as the control mode from the determination information, and performs the white balance correction according to the selected mode.

[0010]

As the one corresponding to human color adaptability by a so-called memory color, which empirically corrects the color temperature change of an object under various light sources such as the sun, an electric bulb, and a fluorescent lamp, the above-mentioned is mainly used. There is a white balance circuit including the infrared sensor 10, the white balance control circuit 19 and the automatic white balance control circuit 24.

Now, this white balance circuit, especially when the power is turned on from the power off state, the AWB
The control circuit 24 must determine the light source in the preset mode based on the infrared information from the infrared sensor 10 so that the white balance (initial white balance) can be obtained immediately.

However, the AWB control circuit 2
Since 4 can detect only the presence or absence of infrared rays based on the infrared information supplied from the infrared sensor 10, for example, when the infrared rays emitted by the light source are detected, it is determined whether the sun or the light bulb which emits the infrared rays is the light source. As a result, it is possible to distinguish between the sun and the light bulb by comparing the color temperatures of the two with various information such as the above-mentioned aperture information, distance information, color information, color difference information, and illuminance information. However, the white balance could not be adjusted accurately without this.

Therefore, even when it takes time to set the white balance of the video signal, or when the photographing location is changed from the outdoor to the indoor or from the indoor to the outdoor, the white balance is corrected each time by referring to the various information described above. Since it is necessary, there were problems such as taking a long time to set and forming a loop that repeats adjustment. Further, there is a drawback that the above-mentioned information judgment criteria cannot be completely set under a delicate photographing condition, which causes a malfunction.

For the above reasons, it is necessary to surely and quickly perform the white balance adjustment suitable for each color temperature by determining whether the light from the light source is from the sun, a light bulb or a fluorescent lamp.

[0015]

In order to solve the above problems, the present invention provides a video camera having the following configuration.

Image pickup means for outputting distance information relating to the distance to the subject, diaphragm means for outputting diaphragm information, focus control means for outputting illuminance information of the imaged image and for focus control of the image pickup means, and the image Color information output means for outputting color information related to the image, infrared information output means for outputting infrared information about infrared rays of the light source for the object, and color difference information output means for outputting color difference information according to a color difference signal related to the image. And a control means for outputting a white balance correction signal obtained based on at least one of distance information, aperture information, illuminance information, color information, infrared information, and color difference information to the color information output means and the white balance control means, respectively. And a blinking information output means for outputting blinking information of a light source in the infrared information to the control means. Video camera and performing a determination of the light source using only infrared information and blink information is connected to the control unit.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A video camera according to the present invention will be described below with reference to FIGS. FIG. 1 is a basic configuration diagram of an embodiment of a video signal system of a video camera of the present invention, and FIG. 2 is a circuit diagram of an embodiment of a flicker detection circuit which is a main part of the present invention. The same components as those described above are designated by the same reference numerals, and the description thereof will be omitted.

The video camera according to the present invention includes the infrared sensor 10 on the output side and the AW in the basic configuration shown in FIG.
The configuration is similar to that in which a flicker detection circuit 1 described later is connected in parallel to a connection line that connects the input side of the B control circuit 24. The configuration is such that an imaging lens (imaging unit) 11 that outputs distance information (so-called zoom information) related to the distance to a subject, a diaphragm unit (diaphragm unit) 12 that outputs diaphragm information, and a Y / C separation circuit 16 An automatic focus control circuit (AF circuit, focus control means) 22 that outputs illuminance information (so-called low contrast information) of the output luminance signal (captured image) and controls the focus of the imaging lens 11, and a color temperature related to the image. A color signal separation circuit (color information output means) 18 for outputting information (color information), and an infrared sensor (infrared information output means) for outputting infrared information (infrared and flicker (flickering) information) regarding infrared rays of a light source of a subject. ) 10 and the color difference signal R relating to the image
-Y, BY An integrator circuit (color difference information output means) 23 for outputting color difference information and at least one of distance information, aperture information, illuminance information, color information, infrared information, and color difference information are obtained. The white balance correction signal is sent to the color signal separation circuit 18 and the white balance control circuit (W
A video camera having an auto white balance control circuit (AWB control circuit, control means) 24 for outputting to a B CTL circuit and white balance control means 19 respectively, and the auto white balance control circuit 24 is a light source in the infrared sensor 10. The flicker detection circuit (blinking information output means) 1 for outputting the flicker information (blinking information) is connected, and the light source is discriminated using only the infrared information and the blinking information connected to the auto white balance control circuit 24. It is a thing.

Now, in the video camera according to the present invention, in particular, the infrared information (infrared and flicker information) output from the infrared sensor 10 in the AWB control circuit 24 and the flicker information output from the flicker detection circuit 1 are used. Based on this, it is possible to determine without delay whether the light source is the sun, a light bulb such as a tungsten electric lamp, or a fluorescent light in fine weather or cloudy weather. As will be described later, the flicker detection circuit 1 detects and outputs to the AWB control circuit 24, as a flicker, a frequency signal according to the power source frequency (for example, 50 Hz or 60 Hz) of the light source included in the infrared information output from the infrared sensor 10.

As is well known, the sunlight and the light of the electric bulb contain infrared rays, respectively, and the electric bulb and the fluorescent lamp respectively have flicker due to the power supply frequency. Therefore, the AWB control circuit 24 uses the infrared sensor 10
“Yes”, “No” of infrared in the infrared information output from
Then, it is possible to immediately discriminate the types of these three light sources according to the combination of "present" and "absent" of the flicker information output from the flicker detection circuit 1.

That is, the AWB control circuit 24: (1) The light source is "bulb" when the infrared ray is "present" and the flicker signal is "present". (2) When the infrared ray is "absent" and the flicker signal is "present". “Fluorescent lamp” (3) When the infrared ray is “present” and the flicker signal is “absent”, the light source is determined to be the “sun”.

As shown in FIG. 2, the flicker detection circuit 1 is composed of an amplifier 2, a comparator 3, resistors R1 to R7, and capacitors C and C1 to C3. The amplifier 2 amplifies the input signal from the resistors R1 and R6, and also the resistors R1 and R6.
6. A bandpass filter for extracting a flicker component (for example, center frequency about 120 Hz, bandwidth about 15 Hz) from the capacitor C1 is formed. The comparator 3 has resistors R2 and R
The reference level is determined by 7. Next, the operation of the flicker detection circuit 1 will be described.

First, when light from a light bulb is received, both infrared light and flicker are present in this light, so the infrared sensor 10 outputs infrared information to the AWB control circuit 24 and the flicker detection circuit 1. The infrared information in this case is a signal formed by superimposing an AC signal indicating the presence of flicker and a noise component on a DC component of a constant level indicating the presence of infrared rays. The flicker detection circuit 1 cuts the direct current component indicating the presence of infrared rays from the signal coming from the infrared sensor 10 by the coupling capacitor C, extracts the alternating current signal and the noise component indicating the presence of flicker, and then connects the resistor R1 and the capacitor C1. It inputs to the amplifier 2 via. The amplifier 2 performs a filtering operation for amplifying the AC signal and the noise component indicating the presence of the flicker and extracting only the AC signal component indicating the presence of the flicker. In this way, the flicker signal, which is an AC signal indicating the presence of flicker output from the amplifier 2, is input to the comparator 3 after passing through the resistors R2 and R3, respectively. Since the level of the flicker signal is higher than the reference level by comparing the level of the flicker signal with the reference level in the comparator 3, the flicker information which is a rectangular pulse signal of "1" is output from here to the AWB control circuit 24. It In this way, the AWB control circuit 24 determines whether the infrared light is “present” and the flicker signal is “present”, determines that the light source is the “bulb”, and immediately outputs the white balance correction signal that is suitable for the light source being the “bulb” as the color signal. It outputs to the separation circuit 18 and the WBCTL circuit 19, respectively. As a result, the color signal separation circuit 18 and the WBC
The TL circuit 19 can quickly obtain a white balance state suitable for the light source being a “bulb”.

Next, when the light of the fluorescent lamp is received, this light does not have infrared rays but only flicker. The infrared information in this case is a signal formed by superposing an AC signal indicating the presence of flicker and a noise component on a DC component of a lower level than a DC component of a constant level indicating the presence of infrared rays.
The flicker detection circuit 1 cuts the direct current component of the infrared information from the signal coming from the infrared sensor 10 by the coupling capacitor C, extracts the alternating current signal and the noise component indicating the presence of flicker, and then through the resistor R1 and the capacitor C1. Input to amplifier 2. The amplifier 2 performs a filtering operation for amplifying the AC signal and the noise component indicating the presence of the flicker and extracting only the AC signal component indicating the presence of the flicker.
In this way, the flicker signal, which is an AC signal indicating the presence of flicker output from the amplifier 2, is input to the comparator 3 after passing through the resistors R2 and R3, respectively. Since the level of the flicker signal is higher than the reference level by comparing the level of the flicker signal with the reference level in the comparator 3, the flicker information which is a rectangular pulse signal of "1" is output from here to the AWB control circuit 24. It In this way, the AWB control circuit 24 determines that the infrared light is “absent” and the flicker signal is “present”, determines that the light source is “fluorescent lamp”, and immediately outputs the white balance correction signal that is suitable for the light source being “fluorescent lamp”. Color signal separation circuit 18
And the WB CTL circuit 19 respectively. As a result,
The color signal separation circuit 18 and the WB CTL circuit 19 can quickly obtain a white balance state suitable for the light source being a “fluorescent lamp”.

Further, when sunlight is received, this light has infrared rays but no flicker. The infrared information in this case is a signal formed by superimposing a noise component on a direct current component of a constant level indicating the presence of infrared rays. The flicker detection circuit 1 cuts a direct current component indicating the presence of infrared rays from the signal coming from the infrared sensor 10 by the coupling capacitor C,
It is input to the amplifier 2 via the resistor R1 and the capacitor C1. In this way, the AC signal indicating the presence of flicker is not output from the amplifier 2, and as a result, the comparator 3 has a flicker signal nonexistence level lower than the reference level. Is A
It is output to the WB control circuit 24. Thus, A
The WB control circuit 24 determines whether the infrared light is “present” and the flicker signal is “absent”, determines that the light source is “sun”, and immediately outputs a white balance correction signal suitable for the light source being “sun” to the color signal separation circuit. 18 and WB CTL circuit 1
Output to 9 respectively. As a result, the color signal separation circuit 18 and the WB CTL circuit 19 can quickly obtain a white balance state suitable for the light source being the "sun".

[0026]

As described above, the video camera of the present invention outputs the distance information regarding the distance to the object, the aperture means for outputting the aperture information, the illuminance information of the captured image, and Focus control means for controlling focus of the image pickup means, color information output means for outputting color information about the image, infrared information output means for outputting infrared information about infrared rays of the light source for the object, and color difference for the image A color difference information output means for outputting color difference information according to the signal, and a white balance correction signal obtained based on at least one of the distance information, aperture information, illuminance information, color information, infrared information, and color difference information. Means and a control means for respectively outputting to the white balance control means, wherein the control means controls the brightness of the light source in the infrared information. Since the blinking information output means for outputting information is connected and the light source is determined only by using the infrared information and blinking information connected to this control means, for example, the light source is the sun, a light bulb, or a fluorescent lamp. It is possible to immediately determine which is the one, and it is possible to reliably distinguish the light source even if the information judgment due to the subtle light amount is wrong. Therefore, the aperture information, the distance information, the color information, the color difference information described above. As compared with the conventional method of sequentially referring to the illuminance information, white balance adjustment can be performed accurately and quickly.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of an embodiment of a video signal system of a video camera of the present invention.

FIG. 2 is a circuit diagram of an embodiment of a flicker detection circuit which is a main part of the present invention.

FIG. 3 is a basic configuration diagram of a video signal system of a conventional video camera.

[Explanation of symbols]

1 Flicker Detection Circuit (Blinking Information Output Means) 10 Infrared Sensor (Infrared Information Output Means) 11 Imaging Lens (Imaging Means) 12 Aperture Section (Aperture Means) 18 Color Signal Separation Circuit (Color Information Output Means) 19 White Balance Control Circuit, WB CT
L circuit (white balance control means) 20 color signal processing circuit 22 automatic focus control circuit, AF circuit (focus control means) 23 integration circuit (color difference information output means) 24 auto white balance control circuit, AW
B control circuit (control means)

Claims (1)

[Claims] 1. An image pickup means for outputting distance information relating to a distance to a subject, a diaphragm means for outputting diaphragm information, a focus control means for outputting illuminance information of a picked-up image and for controlling focus of the image pickup means. Color information output means for outputting color information about the image, infrared information output means for outputting infrared information about infrared rays of a light source for the object, and color difference information for outputting color difference information according to a color difference signal about the image Control for outputting a white balance correction signal obtained based on at least one of distance information, aperture information, illuminance information, color information, infrared information, and color difference information to the color information output means and the white balance control means, respectively. And a blinking information output means for outputting blinking information of a light source in the infrared information to the control means. A video camera characterized in that the light source is discriminated using only infrared information and blinking information connected to the control means.