JPH06197366A - White balance controller - Google Patents

Abstract

PURPOSE:To collect information required for white balance control in a short time with high accuracy. CONSTITUTION:A coefficient K getting smaller as a brightness signal Y obtained by a picture signal processing circuit 2 reaches an upper limit or over and a lower limit or below is generated, the coefficient K is multiplied respectively with color difference signals R-Y, B-Y, each multiplication output is integrated for each frame by a frame signal W at an integration circuit 3 and integration data are fed to a white balance control circuit 7. Thus, data of high brightness portion and low brightness portion are decreased and the data are accurately collected without decreasing the frame.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a white balance control device used in a video camera or the like.

[0002]

2. Description of the Related Art FIG. 3 shows a white balance control device in a conventional video camera.
Is a CCD as an image sensor, 2 is a digital image signal processing circuit (hereinafter referred to as DSP) for processing an image signal obtained from the CCD 1, and 3 is a luminance signal Y and color difference signals RY and BY obtained from the DSP 2. Is a digital integrator circuit that integrates each of the two, and includes an adder 4 and a register 5.

Reference numeral 6 is a frame signal W indicating the integration area of the integration circuit 3.
Is a white balance control circuit for controlling the white balance of the DSP 2 based on the integrated value of the integration circuit 3.

Although only one integrator circuit 3 is shown, it is assumed that three integrator circuits 3 are provided for each of the signals Y, RY and BY.

FIG. 4 shows an image pickup screen 8 formed by the CCD 1, 9 is a frame into which the image pickup screen 8 is divided, and 9a is a high-brightness frame which will be described later.

Next, the operation will be described. The image signal obtained from CCD1 is added to DSP2, where A / D
After the conversion, predetermined signal processing is performed, and the processed signal is D / A converted and output as a video signal.

Signals Y, RY, and BY obtained during processing in the DSP 2 are digitally integrated by the integrating circuit 3. At that time, the frame signal W output from the frame generation circuit 6 is integrated for each frame 9 shown in FIG. 4B, for example. The white balance control circuit 7 uses the integrated data obtained for each frame 9 to perform white balance control on the DSP 2.

When the white balance control circuit 7 uses the integrated data, the white balance control circuit 7 is not suitable for white balance control in the image pickup screen 8 of FIG. 4A, for example, FIG. 4B.
In this case, the integrated data obtained from the frame 9a having a high luminance and a color skip is excluded. As a result, highly accurate white balance control can be performed.

[0009]

Since the conventional white balance control device is configured as described above, the frame 9 is used to remove an inappropriate part such as a high brightness part from the screen.
If the size of is too large, too many parts are excluded, and accurate data cannot be detected. . Conversely, frame 9
If the size is too small, you will spend a lot of time collecting data. For example, even if there is a small high-intensity part in the frame 9a when the frame 9 is large as shown in FIG. 4C, all of the frame 9a will be excluded.
Further, if the frame 9 is small as in (d), the brightness does not drop even if the frame 9a is excluded, but it takes a lot of time to collect data for one screen.

The present invention has been made to solve the above problems, and an object thereof is to obtain a white balance control device capable of collecting correct data without making the frame small.

[0011]

In the present invention, the white balance control device multiplies the coefficient generation means for generating the coefficient K as shown in FIG. 2 according to the luminance signal Y and the coefficient and the color difference signal. A multiplying unit and an integrating unit that integrates the multiplied value for each frame are provided.

[0012]

The ratio of the information where the color component cannot be detected normally such as high brightness and low brightness is small, and accurate data can be collected without making the size of the frame unnecessarily small.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, parts corresponding to those in FIG. 3 are denoted by the same reference numerals, and overlapping description will be omitted.

In FIG. 1, 10 is a coefficient unit for generating a coefficient K according to the magnitude of a luminance signal Y obtained from the DSP 2, and 11 is color difference signals RY, B- obtained from the DSP 2.
This is a multiplier for multiplying Y and the coefficient K, and the multiplication output is integrated by the integrating circuit 3. It should be noted that two multipliers 11 and two integrating circuits 3 are provided for RY and BY.

Next, the operation will be described.

FIG. 2 shows the relationship between the coefficient K of the coefficient unit 10 and the luminance signal Y. In the absence of the signal Y, the coefficient K is obtained.
Is “0”, and as the signal Y increases from there, the coefficient K also increases, the coefficient K becomes “1” at the point A, and thereafter becomes constant. When the signal Y increases to the point B, it starts decreasing from that point, and the coefficient K decreases until the signal Y becomes "0".

In FIG. 1, the color difference signals R-Y and B-Y are respectively multiplied by the coefficient K in the multiplier 11.
The multiplication value is integrated by the integration circuit 3 for each frame by the frame signal W from the frame generation circuit 6, and each integrated data is added to the white balance control circuit 7. The white balance control circuit 7 sequentially collects data, and when the data for one screen is collected, the white balance control of the DSP 2 is performed based on the result.

According to the above, the luminance is a predetermined upper limit value (see FIG. 2).
The value of the integrated data obtained within a frame higher than the point B) becomes smaller as the brightness becomes higher. Further, the value of the integrated data obtained in the frame in which the brightness is lower than the predetermined lower limit value (point A in FIG. 2) becomes smaller as the brightness becomes smaller. That is, the proportion of information in places where the color component cannot be detected normally, such as where brightness is high and where brightness is low, is small. Therefore, the white balance control circuit 7 may use all the collected data, and it is not necessary to remove the unsuitable portion of the data as in the conventional case.

Therefore, the accuracy is not deteriorated while collecting data in a short time without particularly reducing the size of the frame 9 in FIG.

[0020]

According to the present invention, the luminance signal shown in FIG.
Since a coefficient such as is generated and the multiplication value of this coefficient and the color difference signal is integrated, the information necessary for controlling the white balance can be obtained in a short time without making the size of the frame unnecessarily small. There is an effect that can be collected accurately.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a relationship between a luminance signal and a coefficient.

FIG. 3 is a configuration diagram of a conventional white balance control device.

FIG. 4 is a configuration diagram for explaining a frame of a screen.

[Explanation of symbols]

 2 Digital image signal processing circuit 3 Integration circuit 6 Frame generation circuit 7 White balance control circuit 10 Coefficient multiplier 11 Multiplier

Claims (1)

[Claims] 1. A coefficient that generates a coefficient that decreases as the level of a luminance signal obtained by processing an input image signal exceeds a predetermined upper limit value and decreases as it decreases below a predetermined lower limit value. Generating means, multiplying means for multiplying the color difference signal obtained by processing the input image signal by the coefficient generated by the coefficient generating means, and multiplying output of the multiplying means for each of a plurality of areas defined on the screen. A white balance control device comprising: an integrating means for integrating; and a white balance control circuit for controlling the white balance of the screen using the integrated output of the integrating means.