JP2003219416A - Video camera equipment - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To improve the image quality and reduce the circuit scale by sharing and using information used for automatic control of a camera and information necessary for compression encoding of a moving image captured by an image sensor. Provided is a video camera device that realizes reduction. A signal from an image sensor is subjected to digital signal processing by a camera signal processing unit, and an evaluation value generation unit uses the signal to generate an evaluation value for performing automatic control of a camera such as an autofocus or an auto iris. I do. On the other hand, image information that has been subjected to digital signal processing is compressed as a moving image.
At this time, the code amount control unit 10 controls the generated code amount to a predetermined rate using the evaluation value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video camera device which has a function of automatically controlling a camera such as auto focus and auto iris and compresses and encodes a moving image captured by an image sensor.

[0002]

2. Description of the Related Art In a video camera device which has a camera automatic control function and compression-codes a moving image captured by an image pickup device, parameters for automatic camera control such as autofocus and auto-iris are included in the image information. It is common to use information on frequency components. On the other hand, when compressing a moving image captured by an image sensor, it is general to use the information of the frequency component of the image information. Although the automatic control of the camera and the compression coding of the image use the same information, they are performed as separate processes (for example, a technique related to this is disclosed in Japanese Patent Laid-Open No. 2001-2001).
-352471 and JP 2001-136475 A).

[0003]

SUMMARY OF THE INVENTION The present invention improves image quality by sharing information used for automatic control of a camera and information necessary for compression coding of a moving image captured by an image sensor. And a video camera device that realizes a reduction in circuit scale.

[0004]

In order to solve the above-mentioned problems, the video camera apparatus of the present invention is configured to control the encoding when the image is compressed using the evaluation value for controlling the operation of the camera section. And Further, the video camera device of the present invention is configured to control the operation of the camera unit by using the code amount information of the compressed image information. Furthermore, the video camera device of the present invention is configured to control the camera unit by using the information of the frequency conversion unit for image compression.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1, 2, and 3 respectively show block diagrams of three embodiments of a video camera device according to the present invention.

(First Embodiment) In FIG. 1, an analog signal taken in by an image pickup device 1 is subjected to digital signal processing by a camera signal processing unit 2. Using the digital signal, the evaluation value generation unit 3 generates an evaluation value for automatically controlling the camera such as autofocus and auto iris.
And the camera control unit 4 controls the camera using the evaluation value.

On the other hand, the image information subjected to the digital signal processing by the camera signal processing unit 2 is temporarily stored in the input buffer unit 5. Then, the motion compensation (MC) unit 6 performs motion compensation on the image information, and the DCT conversion unit 7 performs frequency conversion. The quantization unit 8 quantizes the frequency-converted information, the variable-length coding unit 9 performs variable-length coding on the quantized information, and the code amount control unit 10 generates the moving image. The moving image compression is performed by performing parameter control so that the code amount becomes a predetermined rate.
At this time, the code amount control unit 10 can use the information of the evaluation value generation unit 3 for automatic camera control.
In the present embodiment, since moving image coding is performed using the evaluation value for camera control as described above, it is possible to obtain a more efficient and high quality reproduced image.

FIG. 4 is a diagram showing an example of the relationship between the camera control value and the evaluation value. The abscissa indicates the camera control value such as the focal length of the camera when controlling the auto focus or the auto iris, and the ordinate indicates the evaluation value such as the frequency component of the input image. For camera control such as auto focus and auto iris, it is most efficient to control the control value of the camera so that the evaluation value is optimum, but for that purpose, the evaluation value of camera control is shifted due to movement of the subject. Every time, all the evaluation values must be generated and evaluated. Generally, this subject is often moving, and the position of the optimum evaluation value for camera control is changing,
Considering the time for controlling the camera, it is difficult to always control the camera with the optimum evaluation value. In addition, an image captured by performing camera control with a non-optimal evaluation value is often an image such as a defocus image, and it is inefficient to accurately perform moving image encoding on such an image.

Therefore, in this embodiment, the threshold of the evaluation value is set experimentally, and the accuracy of the moving image coding is adjusted according to the level. Specifically, for example, it is assumed that the locus of the evaluation value changes from A to B as shown in FIG. At that time, the evaluation value for controlling the camera is a → a '
→ It will change like b. When the evaluation value is small, such as a ′, it is determined that the evaluation value is not the optimum evaluation value for camera control, and the quantized coefficient after frequency conversion is increased to roughly perform moving image coding. On the other hand, in places where the evaluation value level is high, such as a and b, it is determined that the evaluation value is optimum, and the quantization coefficient used for moving image coding is reduced to perform more accurate coding. Moreover, this threshold is not only determined experimentally, but also for each image,
It can be optimized for each frame.

(Second Embodiment) FIG. 2 shows a second embodiment. The analog signal taken in by the image pickup device 1 is subjected to digital signal processing by the camera signal processing unit 2, and moving image compression is performed as in the first embodiment. Then, here, the evaluation value generated by the code amount control unit 10 is used, and the camera control unit 4 controls the auto focus and the auto iris. In the present embodiment, since the camera control is performed by using the information of the code amount control unit 10 that controls the code amount in the moving image encoding, it is possible to reduce the circuit scale.

First, a parameter X representing the complexity of the frame is used as an evaluation value for autofocusing. X = Qp × B (1) Here, Qp represents the average quantization coefficient in the previous frame, and B represents the generated code amount. The autofocus controls the camera by adjusting the complexity X to be large. Regarding the auto iris, adjustment is performed so that the average value of the image is close to the value of the previous frame.

In general, in moving image coding, code amount control is performed in order to keep the code amount constant. In this method, bits are assigned to a certain unit, for example, a frame unit, and actual encoding is performed with the bit allocated. Video cameras are often taken by hand,
In many cases, many bits are required when encoding a moving image due to camera shake or the like, as compared with a normal television or the like. Therefore, more bits are required than the allocated bit amount for encoding, which causes a failure in moving image encoding. In such a case, usually, the accuracy of the moving image coding is roughened to reduce the code amount. I will end up.

Therefore, in the present embodiment, when the moving image coding is likely to fail in this way, the generated code amount is suppressed by the camera control, and the code amount corresponding to that is allocated to the remaining frames, which is visually preferable. Generate a playback image. Specifically, first, the threshold set in the evaluation value generated by the code amount control unit is set, and when the code amount control unit determines that the moving image coding is likely to fail, the autofocus of the camera is set to the threshold value. Limit by position.

FIG. 5 is a diagram showing an example of the relationship between the autofocus control value and its evaluation value. The vertical axis represents the evaluation value generated by the code amount control unit 10, and the horizontal axis represents the autofocus control value. The camera is controlled at the position of the current point a, and when the evaluation value takes a value of X, the camera is controlled so that the point c is the maximum evaluation value, but the encoding fails. When it is determined that the camera has come, the camera control is performed by limiting the camera control to the position of the threshold of the evaluation value (point b). As a result, by blurring the input image, it is possible to obtain an effect that is substantially equivalent to applying a low-pass filter to the input image.

(Third Embodiment) FIG. 3 shows a third embodiment of the present invention. The analog signal taken in by the image pickup device 1 is subjected to digital signal processing by the camera signal processing unit 2, and moving image compression is performed as in the first or second embodiment. Then, at that time, the information subjected to the frequency conversion by the DCT conversion unit 7 is converted into an evaluation value necessary for camera control such as autofocus and auto iris by the evaluation value conversion unit 11, and this is used to control the camera. The configuration is such that the unit 4 controls the camera.

In this embodiment, since the camera is controlled by using the information of the frequency component necessary for the moving image coding obtained by the DCT conversion unit 7, the evaluation value for the camera control is individually used as in the conventional case. It is not necessary to generate the, and the circuit scale can be reduced.

Generally, in moving picture coding, hybrid coding is used in which a motion compensation (MC) section for removing redundancy in the time direction and a DCT transform section for removing redundancy in the spatial direction are combined. ing. At this time, the DCT conversion section is a section that frequency-converts the image information by paying attention to the feature that the image information contains many low-frequency components. In the international standard method of moving picture coding, DCT is used for this frequency conversion.
Although conversion is generally used, other frequency conversions such as FFT and Wavelet conversion can also be used in the present embodiment.

On the other hand, in camera control such as auto focus and auto iris, it is general to use the information of the frequency component of the image. Therefore, in this embodiment, the frequency component information calculated for moving image coding is used for camera control. Specifically, the frequency component generated by the frequency conversion unit for moving image coding is converted into an evaluation value suitable for camera control, and camera control is actually performed. The conversion into the evaluation value can significantly reduce the circuit scale as compared with the conventional generation of the evaluation value.

[0019]

According to the present invention, the information used for the automatic control of the camera and the information necessary for the compression coding of the moving image captured by the image sensor are shared and used to improve the image quality and the circuit. A reduction in scale can be realized.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of a video camera device according to the present invention.

FIG. 2 is a block diagram showing a second embodiment of a video camera device according to the present invention.

FIG. 3 is a block diagram showing a third embodiment of a video camera device according to the present invention.

FIG. 4 is a diagram showing an example of a relationship between a camera control value and an evaluation value for camera control.

FIG. 5 is a diagram showing an example of a relationship between a camera control value and an evaluation value for camera control.

[Explanation of symbols]

1. Image sensor unit 2 ... Camera signal processor 3 ... Evaluation value generator 4 ... Camera control unit 5: Input buffer section 6 ... MC section 7 ... DCT converter 8 ... Quantizer 9 ... Variable length coding unit 10 ... Code amount control unit 11 ... Conversion unit to evaluation value

Continued front page    (72) Inventor Masashi Takahashi             292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa             Ceremony Hitachi Digital Media Development Book             Department F-term (reference) 5C022 AB04 AB12 AB28 AB29 AC69                 5C059 KK07 MA05 MA23 MA24 MC11                       MC38 ME01 NN21 PP04 SS14                       TA00 TA46 TB04 TC00 TC02                       TC04 TC10 TC18 TD03 TD12                       UA02

Claims (4)

[Claims] 1. A video camera device for compressing and encoding an image signal captured from an image sensor, comprising: a camera section having the image sensor; a camera control section for controlling the operation of the camera section; and a camera control section. An evaluation value generation unit that generates an evaluation value used for control, a camera signal processing unit that performs digital signal processing on the analog image signal captured from the image sensor, and an image processed by the digital signal from the camera signal processing unit An image compression unit for image-compressing information, and a code amount control unit for controlling the code amount of the image information generated by the image compression unit to a predetermined rate are provided. A video camera device, wherein image coding is controlled using an evaluation value generated by a value generation unit. 2. A video camera apparatus for compressing and encoding an image signal captured from an image sensor, comprising: a camera section having the image sensor; a camera control section for controlling the operation of the camera section; and a camera control section. An evaluation value generation unit that generates an evaluation value used for control, a camera signal processing unit that performs digital signal processing on the analog image signal captured from the image sensor, and an image processed by the digital signal from the camera signal processing unit An image compression unit for image-compressing information, and a code amount control unit for controlling the code amount of the image information generated by the image compression unit to a predetermined rate are provided. A video camera device, characterized in that the camera unit is controlled by using information on a code amount of image information from a control unit. 3. A video camera device for compressing and encoding an image signal captured from an image pickup device, comprising: a camera unit having the image pickup device; a camera control unit for controlling the operation of the camera unit; and a camera control unit. An evaluation value generation unit that generates an evaluation value used for control, a camera signal processing unit that performs digital signal processing on the analog image signal captured from the image sensor, and an image processed by the digital signal from the camera signal processing unit A frequency conversion unit that converts information into a frequency domain, an image compression unit that includes the frequency conversion unit and that compresses image information that has undergone digital signal processing, and a code amount of the image information that is generated by the image compression unit to a predetermined amount. The camera control is provided with a code amount control unit that performs control for setting a rate, and an evaluation value conversion unit that converts information of the frequency conversion unit into an evaluation value. Using the evaluation value converted by the evaluation-value converting unit, a video camera apparatus characterized by controlling the camera unit. 4. The video camera device according to claim 2, wherein the code amount control unit generates an evaluation value for the camera control unit to perform camera control, and the camera control unit includes the code amount control unit. A video camera device characterized in that the operation of the camera unit is restricted according to the level of the evaluation value generated by.