JPH06233310A - Iris controller for video camera - Google Patents

Abstract

PURPOSE:To obtain a natural image by providing an iris control means, a highlight part detector means, a chrominance signal suppressor means, and a chrominance signal suppressed variable detector means to operate the chrominance signal suppressed variable and the iris control signal and by control ling the opening of an iris. CONSTITUTION:A color suppression detector circuit 16 detects the number of chrominance signals which are suppressed by a highlight part color suppressor circuit 14 and outputs this detecting result to a detection amplifier circuit 17. That is, the circuit 16 detects the suppressed variable of the chrominance signal from the difference between the input and the output of the chrominance signal of the circuit 14. The circuit 17 detects and amplifies the suppressed variable of the chrominance signal and acquires a DC potential signal corresponding properly to the iris control signal to output the potential signal to an adder circuit 18. The circuit 18 is provided on a signal path set between a detection circuit 6 and an iris driving circuit 7 and adds the white signal suppressed variable to the iris control signal of the output of the circuit 6. The circuit 7 controls the opening of an iris 2 based on the signals added together.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an iris control device for a video camera such as a video tape recorder (VTR) separate video camera or a VTR integrated video camera.

[0002]

2. Description of the Related Art There are various types of video cameras for broadcasting, professional use, and home use, and all of them require high image quality as basic performance. Particularly for household use, in addition to such good image quality, the importance of operability, convenience, and low cost is increasing. Therefore, in order to achieve a simple operation, the adjustment of the iris (iris meter, diaphragm) of the lens is automated, and technical development is underway to minimize the need for manual adjustment.

FIG. 3 shows that the iris adjustment is automated.
It is a block diagram of a signal processing system of a conventional video camera,
The operation of the video camera will be described with reference to FIG. The light from the image to be photographed passes through the lens 1, the amount of light is controlled by the iris 2 and enters the CCD (charge coupled device) type image pickup device 3, and is photoelectrically converted by the image pickup device 3 to obtain a video signal (image pickup image). Video signal). This video signal is a CD
The S (correlated double sampling) circuit 4 removes the low-frequency noise component and inputs it to the gate / weighting circuit 5 and the AGC (automatic gain control) circuit 8.

In the gate / weighting circuit 5, the input video signal is weighted so that the signal ratio of, for example, the central portion and the lower portion of the screen increases, and the weighted signal is input to the detection circuit 6. The detection circuit 6 converts the weighted video signal into a DC potential signal (iris control signal) and inputs this potential signal to the iris drive circuit 7. The iris drive circuit 7
The opening of the iris 2 is controlled by driving the drive unit (motor or meter) 2a so that the input potential signal becomes constant. Further, the AGC circuit 8 controls the signal level of the video signal input from the CDS circuit 4 and processes the controlled video signal as a Y signal (luminance signal: brightness signal is also equivalent, the same applies hereinafter) processing circuit 9. Is input to the color signal separation circuit 11.

In the Y signal processing circuit 9, γ correction and aperture compensation are performed on the input video signal to obtain the γ
The corrected video signal is input to the Y encoder circuit 10 and the highlight detection circuit 13. Y encoder circuit 10
Performs processing such as blanking insertion, black clip, setup addition, white clip, and synchronization signal addition on the input video signal, and outputs the processed signal as a video camera Y signal to a VTR unit (not shown). . Further, the highlight detection circuit 13 extracts the highlight part of the image from the signal of the Y signal processing circuit 9.

On the other hand, in the color signal separation circuit 11, a color signal component is generated, and in the color signal processing circuit 12, color γ correction, matrix correction, white balance control, color difference signal generation, etc. for the color signal component. Is processed. The color signal (color difference signal) subjected to each of these processes is input to the highlight portion color suppression circuit 14.

The highlight color suppression circuit 14 suppresses the input color signal according to the signal level of the output of the highlight detection circuit 13. That is, it prevents excessive coloring of the highlight portion in the photographed picture. The color signal whose color has been suppressed in the highlight portion is subjected to blanking processing, burst signal addition, chroma modulation, etc. in the color encoder circuit 15 and is output to the VTR portion as a color signal of the video camera.

[0008]

However, in the video camera having the above-mentioned conventional structure, the iris 2 is controlled by the gate / weighting circuit 5 based on the output video signal of the image pickup device 3, such as center-weighted, down-weighted, etc. Was detected and detected, and the iris 2 was controlled so that the voltage level of this potential signal was constant. Therefore, although there is a highlight part due to backlight in some shooting scenes, There is a problem in that the iris 2 becomes too wide open, causing color skipping in highlight areas and the like, which may impair image quality and image quality.

Incidentally, in relation to the present invention, JP-A-60-2
Japanese Patent No. 8382 discloses a video camera control circuit. This circuit detects only a signal that exceeds a certain level when the video signal has a highlight portion, detects this signal, and adds the detected potential signal to the potential signal for iris control, so that it can be used during backlight shooting. In this case, the iris is prevented from being opened too much in the case of, for example, and an abnormally large blooming or comet tail is suppressed in the highlight part, and the image part to be photographed is not too black.

However, the technique disclosed in the above publication merely detects the highlight portion in order to suppress blooming or comet tail due to the amount of light exceeding the photoelectric conversion characteristics of the image pickup device. At this time, the Y signal and the color signal are detected. Was not taken into consideration. Therefore, if the iris is opened too much when there are many color signals, there is a problem in that color suppression is increased, and color skipping occurs, resulting in an unnatural image, which deteriorates image quality and quality.

The present invention has been made in order to solve the above-mentioned conventional problems, and it is possible to prevent the iris from opening too much by considering the luminance signal (Y signal) and the chrominance signal. An iris control device for a video camera that can improve the image quality and quality by obtaining a natural image with no color skipping, because the iris does not open too much when there are many signals and the color suppression does not increase. The challenge is to provide.

[0012]

According to the present invention, a target exposure is obtained based on an output video signal of an image sensor in an iris control device of a video camera for capturing a target image with an image sensor and converting it into a video signal. Iris control means for outputting such an iris control signal, iris drive means for controlling the opening of the iris based on the iris control signal, and for detecting the highlight portion of the luminance signal in the video signal A highlight part detecting means, a color signal suppressing means for suppressing a color signal in the video signal according to the detected highlight part, and a color signal amount suppressed by the color signal suppressing means A color signal suppression amount detecting means calculates the detected color signal suppression amount and the iris control signal to limit the iris opening when the color signal suppression amount increases. By having a fit calculation means, it is intended to solve the above problems.

[0013]

In the present invention, the iris opening is limited by the color signal suppression amount suppressed by the color signal suppression circuit according to the detection signal of the highlight portion. That is, even if there is a highlight portion only in the luminance signal (Y signal) component in the video signal, there is no color signal, and in an image in which color suppression is not performed, the quality and quality of the image can be degraded even if the iris is opened too much. There are few restrictions, so no restrictions are imposed. On the other hand, if the iris opens too much when there are many color signals, color suppression also increases,
Color skipping results in an unnatural image, which impairs quality.Therefore, limiting the iris opening too much by the color suppression signal amount in the highlight part improves the quality and quality of such images. You can

[0014]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a signal processing system of a video camera according to an embodiment of the present invention. Further, FIG. 2 is an explanatory diagram of the effect of the present invention. In addition, in FIG.
The same numbers are given to the same parts as above and the description thereof is omitted. Further, the configuration of FIG. 1 is an example of the present invention, and the present invention is not limited to this, and other configurations may be adopted as long as the present invention can be implemented.

As shown in FIG. 1, the video camera of the embodiment is the video camera of FIG. 2 further provided with a color suppression detection circuit 16, a detection amplification circuit 17, and an addition circuit 18.

The color suppression detection circuit 16 detects the amount of color signals suppressed by the highlight color suppression circuit 14 (color signal suppression amount) and outputs the detected amount to the detection amplification circuit 17. That is, the color suppression detection circuit 16 detects the color signal suppression amount from the difference between the input and output of the color signal of the highlight portion color suppression circuit 14.

The detection / amplification circuit 17 detects and amplifies the color signal suppression amount, obtains a DC potential signal appropriately corresponding to the iris control signal, and outputs it to the addition circuit 18.

The adder circuit 18 is arranged in the signal path between the detection circuit 6 and the iris drive circuit 7, and adds the color signal suppression amount to the iris control signal output from the detection circuit 6. The iris drive circuit 7 controls the opening degree of the iris 2 by this addition signal.

The operation of the embodiment will be described. Since the video camera of the embodiment is configured as described above, under the condition that the signal level of the highlight part is not high and the amount of color suppression signal is small, the opening control of the iris 2 is generally performed by the CDS circuit 4.
Output signal (specifically, its detection voltage). The control is similar to that of the video camera shown in FIG. 2, and the description thereof is omitted. On the other hand, in the iris control under the condition that the amount of color signal suppression is large, since the amount of color signal suppression is added to the detection voltage, opening of the iris 2 is limited.

Further, even if there is a highlight portion in the luminance signal (Y signal component), there is no color signal, and in an image in which color suppression is not performed, there is no restriction on the iris 2 opening too much. Does not occur, and the quality and quality of the image are not degraded so much that no problem occurs. On the other hand, if the iris 2 opens too much when there are many color signals, color suppression also increases. For this reason, if the iris opening is controlled as in the conventional case, in the highlight portion where the Y signal level is high, for example, the color signal suppression amount increases as shown in FIG. Since the level becomes small, color skipping occurs, resulting in an unnatural image and impairing the quality. On the other hand, in the embodiment, the iris opening is limited (the iris opening is narrowed) by the color signal suppression amount in the highlight portion. As a result, for example, as shown in FIG. 2B, the level of the highlight part is lowered,
As a result, the amount of color signal suppression is reduced, so that color skipping in the highlight portion is eliminated, and the quality and quality of the image can be improved.

In other words, the large amount of color suppression signal means that the iris 2 is too wide open, and the conventional video camera causes a large amount of color skipping. It is possible to obtain a high-quality and high-quality picked-up image with little or no color skipping in the light section.

There are various factors causing the iris to open. Therefore, in order to make the picture as natural as possible under various shooting conditions of the subject, the video signal is gate-weighted.
However, even in that case, there are times when the iris is too open, and under these conditions, an unnatural image in which color skip occurs may occur. In this embodiment, it is possible to improve such an unnaturalness of color skip.

In the above embodiment, the color signal suppression amount is detected from the color signal composed of the color difference signals output from the highlight color suppression circuit 14 to prevent the iris from opening too much. The color signal is not limited to this. In short, it is only necessary to detect the suppressed color signal amount.
For example, as indicated by a broken line 12a in FIG. 1, the same effect can be obtained even if the color signal suppression amount is detected from the chroma modulated color signal.

[0024]

As described above, according to the present invention, even if the luminance signal (Y signal component) has a highlight portion, there is no color signal, and in an image in which color suppression is not performed, even if the iris is too wide, the image There are few restrictions on the quality and quality of the products, so no restrictions are added. On the other hand, if the iris is opened too much when there are many color signals, color suppression also increases, and if the iris opening is controlled as in the conventional case, color skipping occurs, resulting in an unnatural image and impairing the quality. However, in the present invention, on the other hand, the iris over-opening is limited by the color suppression signal amount in the highlight portion. Therefore, it is possible to prevent the iris from opening too much in consideration of the luminance signal (Y signal) and the color signal, so that the iris does not open too much and the color suppression does not increase when there are many color signals.
Therefore, it is possible to obtain an excellent effect that it is possible to obtain a natural image in which color skipping does not occur and improve the quality and quality of the image.

[Brief description of drawings]

FIG. 1 is a block diagram showing a signal processing system of a video camera according to an embodiment of the present invention.

2A and 2B are explanatory diagrams of effects of the present invention, in which FIG. 2A is a graph showing a color signal level of a conventional device, and FIG.

FIG. 3 is a block diagram showing a signal processing system of a conventional video camera.

[Explanation of symbols]

 2 Iris 6 Detection circuit 7 Iris drive circuit 13 Highlight detection circuit 14 Highlight color detection circuit 16 Color suppression detection circuit 17 Detection amplification circuit 18 Addition circuit

Claims (1)

[Claims] 1. An iris control device for a video camera, which captures a target image with an image sensor and converts it into a video signal, and outputs an iris control signal for obtaining a target exposure based on an output video signal of the image sensor. An iris control unit for controlling the opening of the iris based on the iris control signal, a highlight section detection unit for detecting a highlight section of the luminance signal in the video signal, A color signal suppressing unit for suppressing a color signal in the video signal according to the highlighted portion; and a color signal suppression amount detecting unit for detecting the color signal amount suppressed by the color signal suppressing unit, And a calculation unit for performing calculation of the detected color signal suppression amount and the iris control signal, and limiting the iris opening when the color signal suppression amount increases. An iris control device for video cameras, which is characterized in that