JP3505864B2 - Video camera - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video camera, and more particularly, to improvement of a video camera suitable when the number of horizontal pixels of a video signal is different between the input side and the output side.

[0002]

BACKGROUND ART As a video camera, there is, for example, one shown in FIG. In the figure, an image formed on the image pickup device 12 by the image pickup optical system 10 is converted into an electric signal by the image pickup device 12 such as a CCD and supplied to the analog signal processing circuit 14. The analog signal processing circuit 14 performs processing such as noise reduction by CDS (correlated double sampling) and gain adjustment by an AGC circuit (not shown). The processed analog video signal is supplied to an ADC (AD converter) 16, where it is converted into a digital video signal and sent to a digital signal processing circuit 18.

The digital signal processing circuit 18 is shown in FIG.
It is configured as shown in FIG. The input digital video signal is first subjected to black level correction by an OB (optical black) clamp circuit 18A, and then,
The signal separation circuits 18B and 18C separate the luminance signal and the color signal. The luminance signal is output after gain adjustment by the Y gain adjustment circuit 18D, gamma conversion by the Y gamma conversion circuit 18E, and aperture correction by the Y aperture compensation circuit 18F. On the other hand, the color signals include white balance adjustment by the white balance circuit 18G, gamma conversion by the color gamma circuit 18H, and synchronization circuit 1.
After line synchronization by 8I and correction by the matrix circuit 18J are performed, the color difference signals RY and BY are output.

The luminance signal and the color difference signal after the digital processing are respectively supplied to the frequency conversion circuit 20 as shown in FIG. The frequency conversion circuit 20 is a circuit for converting the number of horizontal pixels of the image pickup device 12 on the input side into the number of horizontal pixels required by the video recording device 22 on the output side, and the frequency conversion circuit 20 shown in FIG. It is composed of a recursive digital filter 20A and a memory 20B. In addition,
In the figure, "TA" is a time delay element, "k" is a multiplication element,
“Σ” represents the summation element. Input data (luminance data,
The color difference data) is sequentially delayed by the time delay element.

Then, the delay data of each time delay element T is multiplied by a coefficient, and the sum of them is calculated and input to the memory 20B. This memory 20B
By reading the stored data of 1 at the frequency on the output side, frequency conversion, that is, conversion of the number of horizontal pixels is performed. The multiplication coefficients kA to kF change for each output data so that each output data of the delay element is interpolated from the corresponding input data. Such processing is performed by the luminance signal Y and the color difference signal R.
-Y and BY are performed respectively.

The video signal after frequency conversion, that is, the luminance signal Y and the color difference signals RY and BY are analog VT, for example.
It is supplied to and recorded in a video recording device 22 (see FIG. 1) such as an R, a digital VTR, an HDD or an optical disk. Alternatively, it is supplied to a communication device or an image compression device and various processing is performed.

However, the above background art has the following disadvantages. (1) The output side, for example, a video recording device such as a VTR is not changed for a long time once the format is determined in order to make the recorded medium compatible. That is, the number of horizontal pixels defined by the format remains unchanged. On the other hand, for the input side, for example, the image pickup device, a device having a high pixel density with a large number of horizontal pixels is developed to improve the performance. Therefore, in order to develop a video camera using an image sensor having a high pixel density, it is necessary to newly redesign a digital signal processing circuit that occupies most of the signal processing circuit of the video camera.

(2) It is necessary to separately design a digital signal processing circuit for a video camera using an inexpensive image pickup device having a small number of horizontal pixels and for a video camera using an expensive image pickup device having a large number of horizontal pixels. is there.

The present invention focuses on the above points,
It is an object of the present invention to provide a video camera which is excellent in mass productivity and which is advantageous in terms of cost because it is not necessary to change the digital signal processing circuit even if the number of horizontal pixels of the image sensor changes. Is.

[0010]

In order to achieve the above object, the present invention provides an image pickup device for outputting an analog video signal.
(12), analog video signal output from this image sensor (12)
Signal that performs predetermined analog signal processing
Signal processing means (14), output from this analog signal processing means (14)
Digitize the analog video signal after processing the applied analog signal
Analog-to-digital conversion means (1
6), converted by this analog / digital conversion means (16)
The digital video signal generated by the recording means on the output side.
Frequency conversion to convert the frequency to the number of horizontal pixels
Means (50), the digital output from this frequency conversion means (50)
Performs predetermined digital signal processing on digital video signals
A digital signal processing means (18)
The conversion means (50) is the analog / digital conversion means (16)
The digital video signal output from the
Luminance / color separation unit (52) to be separated, this brightness / color separation unit (52)
Output side recording for each component signal separated by
Frequency conversion so that the number of horizontal pixels required by
The frequency converter (54) to perform, by this frequency converter (54)
Luminance / color that synthesizes the signal of each component after frequency conversion
A digital signal processing unit, which comprises a synthesizing unit (56)
The means (18) synthesizes the luminance / color synthesizer (56).
It is characterized in that the signal is used to perform digital signal processing .

Another invention outputs an analog video signal.
Image sensor (12), analog output from this image sensor (12)
The specified analog signal processing is performed on the video signal.
Analog signal processing means (14), this analog signal processing means (1
4) The analog video signal after processing the analog signal output from
Analog / digital conversion that converts the digital signal into a digital video signal.
The conversion means (16), the analog-digital conversion means (16)
The digital video signal converted by the
Frequency conversion so that the number of horizontal pixels required by
The wave number conversion means (50) outputs from this frequency conversion means (50).
The specified digital signal processing
Equipped with digital signal processing means (18)
The frequency conversion means (50) is used for the analog / digital conversion.
The digital video signal output from the means (16) is used as a luminance component.
Luminance / color separation unit (52) for separating into color components, this brightness / color component
Output for each component signal separated by the separating part (52)
Frequency so that the number of horizontal pixels required by the recording means on the side is
A frequency conversion unit (54) for performing number conversion,
The digital signal processing means (18) includes the frequency conversion unit.
Using the signal of each component after frequency change by (54),
It is characterized by performing digital signal processing .

[0012]

The above and other objects, features and advantages of the present invention will be apparent from the following detailed description and the accompanying drawings.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to Examples. The same reference numerals are used for those corresponding to the background art described above.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows main blocks of a video camera according to an embodiment. Compared with the background art described above, the order of the digital signal processing circuit and the frequency conversion circuit is reversed, and the frequency conversion circuit 50 and the digital signal processing circuit 18 are connected in this order to the output side of the ADC 16. There is.

Here, focusing on the digital signal processing circuit 18, in the background art described above, the connection order is before frequency conversion. Therefore, the digital signal processing circuit 1
8 operates with the number of horizontal pixels of the image sensor 12. On the other hand, in the case of the present embodiment, the connection order is after frequency conversion, and the video recording device 22 operates with the number of horizontal pixels. Further, focusing on the frequency conversion circuit, in the background art, the number of horizontal pixels is converted with respect to the luminance signal Y and the color difference signals R-Y and B-Y. The number of horizontal pixels is converted for the 12 output signals.

First, the image pickup device 12 will be described in detail.
As shown in FIG. 2 (A), the image sensor 12 has M pixels for each pixel.
It has a structure in which g, G, Cy, and Ye color filters are stacked. Then, the charges of the adjacent two upper and lower pixels are added together to form an output video signal. For example, in the horizontal line N of the field 1, the charge signals of the pixel lines Lm and Lm + 1 in the figure are added and read. In the horizontal line N + 1 of the field 1, the charge signals of the pixel lines Lm + 2 and Lm + 3 in the figure are added and read. On the other hand, in the horizontal line n of the field 2, the charge signals of the pixel lines Lm + 1 and Lm + 2 in the figure are added and read. In the horizontal line n + 1 of the field 2, the charge signals of the pixel lines Lm + 3 and Lm + 4 in the figure are added and read. The same applies to other horizontal lines.

Next, pay attention to the added signal in each horizontal line. For example, the pixel P of the horizontal line N of the field 1
The added signals of 1, P2, P3, ... Become Mg + Cy, G + Ye, Mg + Cy, ... As shown in FIG. Here, Mg = R + B, Cy = B + G, Ye = R +
If G and Y = 2R + 3G + 2B, the first pixel P1
Is

[0019]     P1 = Mg + Cy = (R + B) + (B + G)         = 2B + G + R ...... See Fig. 2 (C)         = (2R + 3G + 2B) / 2 + (2B-G) / 2         = Y / 2 + (2B-G) / 2 (1) Becomes Similarly, the second pixel P2 is

P2 = G + Ye = G + (R + G) = 2G + R ... See FIG. 2 (C) = (2R + 3G + 2B) / 2- (2B-G) / 2 = Y / 2- (2B-G) / 2. 2) For the third and subsequent pixels, the above is repeated. 2C, fSI is a sampling frequency of the output signal of the image sensor 12 in the ADC 16.

As is apparent from these equations (1) and (2), the luminance signal Y is modulated with the color component (2B-G) / 2 at half the sampling frequency fSI of the image sensor 12. The superimposed signal, in other words, the signal of the modulated color component is the signal added to the luminance signal. The same applies to video signals of other horizontal lines. Such a video signal is supplied from the ADC 16 to the frequency conversion circuit 50.

Next, the frequency conversion circuit 50 is constructed as shown in FIG. 3, and includes a brightness / color separation section 52, a frequency conversion section 54, and a brightness / color synthesis section 56. Of these, the luminance / color separation unit 52 has a configuration as shown in FIG. 4, and includes an interpolation filter 52A, an LPF 52B, a color demodulation circuit 52C, and subtractors 52D and 52E. The interpolation filter 52A includes a time delay element T and a multiplication element k1.
~ K4, summation element ΣA is included. The LPF 52B has a time delay element T, multiplication elements k5 to k7, and a summation element ΣB.
It is included. The color demodulation circuit 52C includes an inverter 6
0, changeover switch 62, and 1/2 multiplier 64 are included. The sum of the multiplication coefficients k1 to k4 of the interpolation filter 52A is "1", and the sum of the multiplication coefficients k5 to k7 of the LPF 52B is "1".

AD shown in FIG. 5A (same as FIG. 2C)
On the other hand, the image sensor output signal from C16 becomes a signal as shown in FIG. 5B by the interpolation filter 52A. On the other hand, the signal of FIG.
52B produces a signal as shown in FIG. The subtractor 52D subtracts the output of the interpolation filter 52A from the output of the LPF 52B. That is, the interpolation filter 52A, the LPF 52B, and the subtractor 52D constitute a BPF, which performs the operations of (A)-(B) of FIG. 5 and performs modulation as shown in (C) of FIG. The separated color components are separated.

The separated color signal is a color demodulation circuit 52C.
To the inverter 60 and the changeover switch 62.
Thus, the inversion is performed for each pixel. As a result, signals of color components as shown in FIG. 5D are obtained. Also,
The separated color signal is multiplied by 1/2 by the 1/2 multiplier 64, and this is subtracted from the input signal by the subtractor 52E to obtain a luminance component signal as shown in FIG. 5 (E). Is obtained.

In the example of the horizontal line n shown in FIG. 5, the color component is 2B-G as shown in the equations (1) and (2), but the next horizontal line n + 1 (see FIG. ) See)
Since the image sensor output changes in the order of G + Cy, Mg + Ye, ..., The color component becomes 2R-G. The same applies to other horizontal lines.

The luminance and color signals separated as described above are supplied to the frequency conversion section 54 as shown in FIG. The frequency conversion unit 54 has the same configuration as the frequency conversion circuit 20 (see FIGS. 10 and 12) of the background art described above, and two sets of the acyclic filter and the memory circuit shown in FIG. 12 are prepared. The frequency conversion of the signals of the luminance component and the color component is performed respectively by.

The converted signals are supplied to the luminance / color combining unit 56 as shown in FIG. This brightness / color combining unit 56
Has a configuration as shown in FIG.
A and a subtractor 56B are included. Color modulation circuit 56A
Is an inverter 70, a changeover switch 72, a 1/2 multiplier 7
It is composed of four. The signals of the luminance component and the color component of the horizontal line n after frequency conversion are as shown in FIGS. 7 (A) and 7 (C). In the figure, fso is a sampling frequency in the video recording device 22.

Of these, the color components after frequency conversion shown in FIG. 7A are inverted pixel by pixel by the inverter 70 and the changeover switch 72 of the color modulation circuit 56A.
It becomes as shown in (B). The signal after this inversion processing is 1/2
The multiplier 74 performs 1/2 multiplication and the adder 56B
Is supplied to. On the other hand, the adder 56B has a configuration shown in FIG.
The luminance components after frequency conversion shown in (C) are input, and these are added to form a combined signal shown in FIG. 7 (D).

This becomes the output of the frequency conversion circuit 50 and is supplied to the digital signal processing circuit 18. In the digital signal processing circuit 18, various processes such as clamping are performed as described above, and the processed luminance signal and color difference signal are supplied to the video recording device 22.

The signal inversion timing in the color demodulation circuit 52C (see FIG. 4) and the color modulation circuit 56A (see FIG. 6) is set so that the horizontal synchronization signal is set in order to prevent the color arrangement from shifting between the input and output. Do it as a standard. However, when the number of horizontal pixels of the image pickup device 12 and the video recording device 22 is even, the vertical synchronizing signal or the frame pulse may be used as a reference.

By the way, in this embodiment, the composite signal of the luminance component and the color component after the frequency conversion is supplied from the frequency conversion circuit 50 to the digital signal processing circuit 18. That is,
Regardless of the number of horizontal pixels in the image sensor 12,
A signal corresponding to the number of horizontal pixels of the video recording device 22 is constantly supplied to the digital signal processing circuit 18 in the next stage. Therefore,
Even if the number of horizontal pixels of the image sensor 12 changes, there is no need to redesign and develop the digital signal processing circuit 18. Therefore, once a digital signal processing circuit that complies with a predetermined standard is designed, the same digital signal processing circuit can be used for that standard regardless of the number of horizontal pixels of the image sensor, and good mass productivity can be obtained. And
The cost of design and development can be reduced.

In the background art, the image quality may be deteriorated because the frequency conversion is performed on the signal after the digital signal processing, but in the present embodiment, the signal after the digital signal processing is directly applied to the video recording apparatus. Since it is supplied, good image quality can be obtained. Further, since the image subjected to image quality adjustment such as aperture correction in the digital signal processing circuit is not subjected to frequency conversion, constant design of those image quality adjustment circuits can be easily performed, which is advantageous in design.

[0033]

Other Embodiments The present invention has many embodiments and can be variously modified based on the above disclosure. For example, the following is also included. (1) The AGC of the analog signal processing circuit 14 may be performed by the digital signal processing circuit 18.

(2) As shown in FIG. 8, in the luminance / color separation unit 52, the LPF5 is output from the output of the interpolation filter 52A.
It is also possible to subtract the output of 2B by the subtractor 52F to obtain a color component. In this case, 2B-G color components can be obtained by shifting the inversion timing of the color demodulation circuit 52C by one pixel. Note that G-2B may be used as it is, but the demodulation and modulation timings are reversed. As for the luminance component, since the modulated color component is inverted, the multiplier 64
It is obtained by multiplying by 1/2 and adding it to the input signal as it is in the adder 52G.

(3) As shown in FIG. 9, in the brightness / color separation unit 52, the brightness component may be separated by another independent LPF 52H. As the LPF 52H, for example, a trap filter can be used.

(4) When the digital signal processing circuit 18 has a circuit configuration in which the luminance component and the color component are used as they are, the output of the frequency converter 54 may be supplied to the digital signal processing circuit 18 as it is. In this case, the luminance / color combining unit 56 can be omitted. (5) The above-mentioned embodiment is a video signal output from the image sensor.
Of the present invention in the case of a video camera for supplying video to a video recording device
However, if the number of horizontal pixels is different,
Frequency conversion in combination The present invention is generally applicable. example
For example, various image processing applications such as video communication equipment and image compression equipment.
For example, the path is the output side.

[0037]

【The invention's effect】 As described above, according to the present invention,
Since digital signal processing is performed after frequency conversion,
The number of horizontal pixels during digital signal processing is affected by the image sensor, etc.
It becomes constant without receiving. Therefore, the type of image sensor changes
Even if the number of horizontal pixels on the input side is converted due to reasons such as
Enables mass production without changing the signal processing circuit
In addition, the cost can be reduced. Digital signal processing
The cost of designing and developing a logic circuit can be reduced. Also, the digital
The video signal after the video signal processing is directly input to a recording means such as a VTR.
Image quality is improved because it is directly supplied.
Simple design of constants for image quality adjustment processing circuit in signal processing circuit
Can be done.

[Brief description of drawings]

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

FIG. 2 is a diagram showing a filter configuration and a signal output of the image sensor of the embodiment.

FIG. 3 is a block diagram showing a configuration of a frequency conversion circuit according to an embodiment.

FIG. 4 is a circuit diagram showing a configuration of a brightness / color separation unit.

FIG. 5 is a diagram showing an operation of a brightness / color separation unit.

FIG. 6 is a circuit diagram showing a configuration of a luminance / color combining unit.

FIG. 7 is a diagram showing an operation of a luminance / color combining unit.

FIG. 8 is a circuit diagram showing another embodiment of the brightness / color separation unit.

FIG. 9 is a circuit diagram showing still another embodiment of the brightness / color separation unit.

FIG. 10 is a block diagram showing a main configuration of background art.

FIG. 11 is a block diagram showing a background-art digital signal processing circuit.

FIG. 12 is a block diagram showing a frequency conversion circuit of the background art.

[Explanation of symbols]

10 ... Imaging optical system 12 ... Image sensor 14 ... Analog signal processing circuit 16 ... ADC 18 ... Digital signal processing circuit 22 ... Video recording device 50 ... Frequency conversion circuit 52 ... Luminance / color separation unit 52A ... Interpolation filter 52B, 52G ... LPF 52C ... Color demodulation circuit 52D, 52E, 52F ... Subtractor 52G ... Adder 54 ... Frequency converter 56 ... Luminance / color composition section 56A ... Color modulation circuit 56B ... Adder

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-6-178305 (JP, A) JP-A-4-319893 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H04N 9/04-9/11 H04N 5/225-5/232 H04N 9/64-9/78

Claims (2)

(57) [Claims] 1. An image sensor (1) for outputting an analog video signal.
2), to the analog video signal output from this image sensor (12)
Analog signal processing that performs predetermined analog signal processing
Means (14), analog output from this analog signal processing means (14)
Converts analog video signals after signal processing to digital video signals
An analog / digital conversion means (16) for conversion, converted by this analog / digital conversion means (16)
Digital video signal is required by the recording means on the output side
Frequency conversion means for frequency conversion so that the number of horizontal pixels becomes
(50), digital video signal output from this frequency conversion means (50)
Digital signal that performs predetermined digital signal processing
Signal processing means (18), and the frequency conversion means (5
0) is the data output from the analog / digital conversion means (16).
Luminance / color that separates the digital video signal into luminance and color components
Separator (52), the signal of each component separated by the luminance / color separator (52)
The number of horizontal pixels required by the recording means on the output side for the
Frequency conversion unit (54) that performs frequency conversion so that each frequency conversion is performed by this frequency conversion unit (54)
If a luminance / color synthesis unit (56) that synthesizes component signals is provided,
In both cases, the digital signal processing means (18)
Digital signal processing using synthesized signal synthesized in (56)
Video camera and performing. 2. An image sensor (1) for outputting an analog video signal.
2), to the analog video signal output from this image sensor (12)
Analog signal processing that performs predetermined analog signal processing
Means (14), analog output from this analog signal processing means (14)
Converts analog video signals after signal processing to digital video signals
An analog / digital conversion means (16) for conversion, converted by this analog / digital conversion means (16)
Digital video signal is required by the recording means on the output side
Frequency conversion means for frequency conversion so that the number of horizontal pixels becomes
(50), digital video signal output from this frequency conversion means (50)
Digital signal that performs predetermined digital signal processing
Signal processing means (18), and the frequency conversion means (5
0) is the data output from the analog / digital conversion means (16).
Luminance / color that separates the digital video signal into luminance and color components
Separator (52), the signal of each component separated by the luminance / color separator (52)
The number of horizontal pixels required by the recording means on the output side for the
A frequency conversion unit (54) that performs frequency conversion so that
In addition, the digital signal processing means (18) causes the frequency conversion section to
Using the signal of each component after frequency change by (54),
A video camera characterized by digital signal processing .