JPH0723413A - Image pickup device - Google Patents

Abstract

PURPOSE:To attain proper white balance correction in both outdoor and indoor positions by detecting a wind noise so as to discriminate whether the device is installed outdoor or indoor and amplifying a color signal at a different gain from the outdoor and the indoor location where a color temperature is largely different. CONSTITUTION:A comparison signal is formed by subtracting the level of a detection signal outputted from a detection circuit 27 from the device of a detection signal outputted from a detection circuit 24 and fed to a wind noise detection circuit 29. When the comparison signal level fed from a pre-stage comparator circuit 28 exceeds continuously a preset threshold level for a predetermined period, it is discriminated that a wind noise signal component having mainly a low frequency component is included in a voice signal generated from a microphone 21 and a wind noise detection signal is fed to a microphone 11. Upon the receipt of the wind noise detection signal from the wind noise detection circuit 29, the microcomputer 11 discriminates the pickup environment to be violent and limit a value possibly received by an RCONT and a BCONT.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup apparatus having a function of judging whether there is wind noise and correcting the white balance based on the judgment result.

[0002]

2. Description of the Related Art Conventionally, an image pickup apparatus such as a video camera is provided with an automatic white balance correction apparatus for automatically adjusting the balance of each color signal. FIG. 5 is a block diagram schematically showing the configuration of this conventional automatic white balance correction apparatus. A conventional automatic white balance correction device will be described with reference to FIG.

In FIG. 5, reference numeral 1 is an image pickup device such as a CCD, 2 is a luminance signal / chromaticity signal generation circuit, 3 is a gain control circuit inserted in a signal line of a red signal R, and 4 is a blue signal B. A gain control circuit inserted in the signal line, 5 is a color difference signal generation circuit, 6 is an encoder, and 7 is a color difference signal (R-
YL) gate circuit, 8 is a color difference signal (B-YL) gate circuit, and 9 and 10 are analog-digital converters (hereinafter A).
/ D converter) and 11 are microcomputers, respectively.

Next, the operation of the above conventional automatic white balance correction apparatus will be described with reference to FIG. Figure 6
In, the light from the subject that has entered from the lens is imaged on the image sensor 1 and photoelectrically converted by the image sensor 1. The electric signal output from the image sensor 1 is a luminance signal.
It is input to the chromaticity signal generation circuit 2. The luminance signal / chromaticity signal generation circuit 2 generates a luminance signal YH having a wide band frequency component, a luminance signal YL having a narrow band frequency component (low frequency), a red signal R, and a blue signal B. It The red signal R and the blue signal B are input to the gain control circuits 3 and 4 for the respective colors, and these gain control circuits 3 and 4 are input.
After being respectively amplified based on the characteristics controlled by the control signal from the microcomputer 11 by 4,
The color signals R'and B'are output. The color signals R'and B'output from the gain control circuits 3 and 4 are luminance signals Y.
It is input to the color difference signal generation circuit 5 together with L, and the color difference signal (R
-YL) and (B-YL) are generated. The color difference signals (R-YL) and (B-YL) are input to the encoder 6 together with the luminance signal YH, where a standard television signal is generated.

Here, the color difference signals (R-YL), (BY)
L) is further input to the gate circuits 7 and 8, and unnecessary signals within the blanking period, abnormal color difference signals due to signal collapse during high-luminance shooting, and the like are removed, and processing such as smoothing is performed. The signals output from the gate circuits 7 and 8 are A
The digital signal (R-Y) is input to the D / D converters 9 and 10.
After being converted into L) AD and (B-YL) AD, they are input to the microcomputer 11. In the microcomputer 11, the gain control signals of red signal R and blue signal B (hereinafter RCONT, BCON), which are the results of predetermined processing described later, are given.
(Referred to as “T”) and is input to the gain control circuits 3 and 4 for the red signal R and the blue signal B.

FIG. 6 is a diagram showing the relationship between RCONT and BCONT and the gains of the gain control circuits 3 and 4. It can be seen from FIG. 6 that the gains of the gain control circuits 3 and 4 increase as the gain control signals RCONT and BCONT increase. Next, FIG. 7 is a flow chart for explaining the processing contents of the microcomputer 11. The processing operation of the microcomputer 11 will be described with reference to FIG.

The microcomputer 11 starts its operation at the same time when the power is turned on, but waits until the vertical synchronizing signal is input in order to perform processing in synchronization with the vertical synchronizing signal (step S2). When the vertical synchronizing signal is input, step S
4 and output signals of the A / D converters 9 and 10 (R
Upon receiving -YL) AD and (B-YL) AD, the operation represented by the following equation is first performed.

S1 = (R−YL) AD− (B−YL) AD (1) Next, between the S1 obtained by the formula (1) and a predetermined reference value REF, the following formula is given. The calculation is performed (step S6). ΔTc = S1-REF (2) The correction amount ΔRCONT from the current RCONT (current) is obtained from the diagram showing the relationship between ΔRCONT and ΔTc shown in FIG. 8, and the new RCONT is obtained from the following equation (step S
8).

RCONT (new) = RCONT (current) + ΔRCONT (3) However, RCONT at color temperatures of 2800K and 8000K
The optimum values of NT are RCONT (2800) and R, respectively.
When expressed as CONT (8000), RCONT (2800) <RCONT <RCONT (8
000).

BCONT is uniquely obtained from FIG. 9 showing the relationship between RCONT and BCONT (step S1).
0). The microcomputer 11 outputs the RCONT and BCONT obtained as described above and inputs them to the gain control circuits 3 and 4. As described above, in the conventional white balance correction device shown in FIG. 5, the gain control circuits 3 and 4, the color difference signal generation circuit 5, the gate circuits 7 and 8, A /
A white balance negative feedback loop including the D converters 9 and 10 and the microcomputer 11 is formed, and a white-balanced color difference signal can be supplied to the encoder 106 within a practical color temperature range.

[0011]

However, in the above-mentioned conventional example, it is premised that the signal smoothed by the gate circuits 7 and 8 has a high correlation with the color temperature of the illumination on the subject. , For example, in the case of a subject of only a single color such as red or blue, it cannot be said that the correlation is high, and particularly under conditions where the color temperature of illumination is different, such as outdoors and indoors, a correction error occurs in the white balance, There is a problem that a correct correction effect cannot be obtained for both conditions.

Therefore, the present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an image pickup apparatus having a small white balance correction error regardless of whether it is outdoors or indoors.

[0013]

In order to solve the above-mentioned problems and to achieve the object, an image pickup device of the present invention comprises an image pickup device and a color for separating a plurality of color signal components from an output signal of the image pickup device. Signal separating means, gain adjusting means for changing the gain of the color signals separated by the color signal separating means, detecting means for detecting wind noise, and adjustment of the gain adjusting means based on the detection result of the detecting means. And a correction unit for correcting the white balance by controlling the amount.

Further, in the image pickup apparatus according to the present invention, the detecting means detects whether or not the voice signal is wind noise by detecting the distribution of frequency components of the voice signal input by the microphone. It is characterized by that.

[0015]

As described above, since the image pickup apparatus according to the present invention is configured, it is possible to judge whether it is outdoors or indoors by detecting the wind noise, and to determine the color signals for the outdoors and the room where the color temperatures greatly differ. By amplifying with different gains, the white balance can be properly corrected both outdoors and indoors.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a diagram showing a configuration of an automatic white balance correction apparatus in an image pickup apparatus according to an embodiment of the present invention. In FIG. 1, since the automatic white balance correction apparatus of this embodiment has the same parts as the conventional automatic white balance apparatus shown in FIG. 5, the same parts are designated by the same reference numerals and their description is omitted. Omit it.

In FIG. 1, reference numeral 21 is a microphone for converting a voice signal into an electric signal, and 22 is a voice signal generated by the microphone 21 for separating a low frequency component as indicated by C in FIG. A bandpass filter, 23 is an amplifier for amplifying the signal separated by the bandpass filter 22, and 24 is a detection circuit for detecting the low frequency component signal of the audio signal amplified by the amplifier 23 and outputting the detected signal. Shows.

Similarly, reference numeral 25 is a bandpass filter for separating middle and high frequency components as indicated by D in FIG. 2 from the audio signal generated by the microphone 21, and 26 is a bandpass filter 25. Reference numeral 27 denotes an amplifier for amplifying the detected signal, and reference numeral 27 denotes a detection circuit for detecting the low frequency component signal of the audio signal amplified by the amplifier 26 and outputting the detected signal.

Further, reference numeral 28 is a comparison circuit which compares the detection signal output from the detection circuit 24 with the detection signal output from the detection circuit 27 and outputs a signal corresponding to the comparison result, and 29 is a comparison circuit 28. When the signal level output from the device continuously exceeds a preset value for a predetermined time, the wind noise detection circuits for notifying the microcomputer in the subsequent stage of the generation of wind noise are shown.

In FIG. 1, the sound collected by the microphone 21 is converted into an electric signal (that is, a sound signal) and supplied to the band pass filters 22 and 25.
FIG. 3 shows the frequency characteristic of the signal output from the microphone 21, where A indicates the frequency characteristic of general voice and W indicates the frequency characteristic of wind noise.
From FIG. 3, it can be seen that the frequency characteristic W of the wind noise is shifted to the lower frequency side than the frequency characteristic A of general voice. The comparison circuit 28 and the wind noise detection circuit 29 are adapted to detect whether or not there is wind noise based on the difference in the frequency characteristics of the general voice and wind noise.

In the present embodiment, when there is wind noise, it is highly possible that the photograph was taken outdoors, that is, the possibility that the color temperature of the illumination light is high is high. Limits the possible values of RCONT and BCONT. Hereinafter, this operation will be described in detail. The band pass filter 22 in FIG. 1 extracts a signal in the frequency band indicated by C in FIG. 2 from the audio signal supplied from the microphone 21. The extracted signal is amplified by the amplifier 23 at the next stage and supplied to the detection circuit 24.
The detection circuit 24 detects a signal in the frequency band indicated by C in FIG. 2 extracted by the bandpass filter 22. A detection signal is output from the detection circuit 24 and supplied to the comparison circuit 28. Further, the band pass filter 25 extracts a signal in the frequency band indicated by D in FIG. 2 from the audio signal supplied from the microphone 21, the extracted signal is amplified by the amplifier 26 at the next stage, and the detection circuit 27 Is supplied to. The detection circuit 27 detects the signal in the frequency band indicated by D in FIG. 2 extracted by the bandpass filter 25. A detection signal is output from the detection circuit 27 and the comparison circuit 2
8 are supplied.

The comparison circuit 28 compares the detection signals output from the detection circuits 24 and 27. Specifically, the detection circuit 27 detects the level of the detection signal output from the detection circuit 24.
The comparison signal is formed by subtracting the level of the detection signal output from the above, and is supplied to the wind noise detection circuit 29. The wind noise detection circuit 29 outputs the audio signal generated from the microphone 21 when the comparison signal level supplied from the comparison circuit 28 in the preceding stage continuously exceeds the preset threshold value for a predetermined period, for example, about 1 second. The wind noise detection signal is supplied to the microcomputer 11 assuming that the wind noise signal component mainly having a low frequency component is included therein. When the microcomputer 11 receives the wind noise detection signal from the wind noise detection circuit 29, it determines that the shooting environment is likely to be outdoors, and limits the values that RCONT and BCONT can take.

FIG. 4 shows an example thereof. In FIG. 4, (a) and (b) show ranges that RCONT and BCONT can take when the photographing environment is likely to be outdoors, and (c) and (b), respectively. (D) indicates the range that can be taken in other cases. In other words, when the shooting environment is outdoors, the values that RCONT and BCONT can take are limited, so even if a white balance correction error occurs, if the subject is close to a single color such as red or blue, the degree of error Will be reduced.

As described above, by adding a simple circuit to the conventional image pickup apparatus, it is considered that there is a high correlation with the color temperature of the light source, such as an object made of only a single color such as red or blue. It is possible to minimize the white balance correction error even for a subject that cannot be said. The present invention can be applied to the modified or modified embodiment described above without departing from the spirit of the invention.

For example, in the above embodiment, the values that RCONT and BCONT can take are limited only by the wind noise detection signal, but other factors such as aperture value, luminance signal,
You may make it restrict | limit by the logic by the combination with a zoom magnification etc. Further, at least a part of the microphone 21 and a circuit connected to the microphone 21 may also be used as a part of a sound recording unit in normal shooting.

Further, in the above embodiment, the method of controlling the white balance based on the color difference signal has been described, but the method of controlling the white balance by using the colorimetric sensor is also applicable.

[0027]

As described above, according to the image pickup apparatus of the present invention, it is possible to judge whether it is outdoors or indoors by detecting the wind noise, and the color signals are greatly different between the outdoors and the room where the color temperature is greatly different. By amplifying with a gain, the white balance can be properly corrected both outdoors and indoors.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an automatic white balance correction apparatus in an image pickup apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing frequency characteristics of a bandpass filter.

FIG. 3 is a diagram showing frequency characteristics of an audio signal output from a microphone.

FIG. 4 is a diagram showing a white balance control characteristic in one embodiment.

FIG. 5 is a diagram showing a configuration of a white balance correction circuit in a conventional image pickup apparatus.

FIG. 6 is a diagram showing a relationship between a white balance control signal and a gain of a gain control circuit in a conventional image pickup apparatus.

FIG. 7 is a flowchart showing an operation of a microcomputer in a conventional image pickup apparatus.

FIG. 8 is a diagram showing a relationship between ΔTc and ΔRCONT.

FIG. 9 is a diagram showing a relationship between RCONT and BCONT.

[Explanation of symbols]

 21 Microphone 22,25 Bandpass Filter 23,26 Amplifier 24,27 Detection Circuit 28 Comparison Circuit 29 Wind Noise Detection Circuit

Claims (2)

[Claims] 1. An image pickup device, a color signal separating device for separating a plurality of color signal components from an output signal of the image pickup device, and a gain adjusting device for changing a gain of the color signal separated by the color signal separating device. An imaging apparatus comprising: a detection unit that detects wind noise; and a correction unit that corrects a white balance by controlling an adjustment amount of the gain adjustment unit based on a detection result of the detection unit. 2. The detection means determines whether or not the voice signal is wind noise by detecting the distribution of frequency components of the voice signal input by the microphone. The imaging device according to.