JPH08307885A - Image pickup device and video signal decoder - Google Patents

Abstract

PURPOSE: To eliminate the need for an expensive A/D converter from a video signal decoder when a video signal is given externally to the image pickup device and decoded and processed digitally with a 1st image signal. CONSTITUTION: A 1st image signal from an image pickup sensor 3 is fed to a switch 21 via an SH/AGC section 4 and a YC separator section 11 or an RGB/YCrCb conversion section 12 generates a luminance signal Y, a chrominance signal C and color difference signals Cr, Cb. A color decode section 14 generates the color difference signals Cr, Cb from the signal C, an image pickup signal conversion section 19 generates a 2nd image signal of the same form as the 1st image signal based on the signals Y, Cr, Cb and gives it to a switch 21. The switch 21 selects the 1st or 2nd image signal and gives the selected signal to a common A/D converter section 5, then it is not required to provide an A/D converter to the decoder section.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup device and a video signal decoding device for converting a video signal into a signal of the same format as a signal picked up by an image pickup means.

[0002]

2. Description of the Related Art FIG. 7 is a block diagram showing a conventional example of an image pickup apparatus capable of inputting an external video signal.

In the figure, 1 is an optical lens, 2 is a diaphragm,
Reference numeral 3 denotes an image sensor such as a CCD that converts an optical signal into an electric signal. Reference numeral 4 denotes an SH / that performs sample hold of an image signal captured by the image sensor 3 and AGC (automatic gain control).
An AGC unit, 5 is an A / D conversion unit, and 6 is a luminance signal and a color difference signal generated from the image signal from the SH / AGC unit 5, or after performing various image processing, the luminance signal and the color difference signal are generated. A digital signal processing unit for generation, a D / A conversion unit 7
Reference numeral 8 designates the image signal from the D / A converter 8 as NTSC or PAL.
Video encoder for converting standard video signals such as 9
Is a timing generator (TG) that generates a timing pulse for moving the image sensor 3, and 10 is a synchronization signal generator (SSG).

Reference numeral 11 denotes a YC separation section for separating an external input signal of the composite signal CVS into a luminance signal Y and a color signal C,
Reference numeral 12 is an RGB / YCrCb converter for converting an externally input video signal of an RGB signal into a luminance signal Y and color difference signals Cr and Cb, and 13A and 13B are various externally input video signals Y,
External input selector switch for switching C, 14 for color signal C
To a two-color-difference signal Cr, Cb, and a color-decoding section 15 for decoding the two-color-difference signal Cr, Cb.
color difference multiplexing switch for multiplexing b into one, 16
A and 16B are external signals A for converting the luminance signal Y and the color difference signals multiplexed into one line into digital signals, respectively.
The D / D conversion unit 17 is a system control unit that performs switching control of the external input changeover switch 13, the color difference changeover switch 23, and the color difference multiplex switch 15 and image pickup control such as autofocus in the processing mode of the digital signal processing unit 6, and 18 The operation units 23A and 23B for the user to perform an input operation relating to imaging on the system control unit 17 are RGB / YCrCb.
Color difference signals Cr and Cb from the conversion unit 12 and the color decoding unit 1
4 is a color difference changeover switch for changing over between the color difference signals Cr and Cb from No. 4.

Next, the operation will be described. The sync signal generator 10 generates a sync signal of a video signal (NTSC, PAL, etc.), and a drive pulse of the image sensor 3 is generated by the timing generator 9 according to the sync signal. The image signal captured by the image sensor 3 is SH / AGC.
Sample hold and AGC (automatic gain control) for removing switching noise and extracting signal components by the unit 4
After that, the A / D conversion unit 5 converts the data into digital data. The image signal converted into digital data is converted into Y / Cr / Cb data by the digital signal processing unit 6, or after various image processing is performed,
The data is converted into Y / Cr / Cb data, and further converted into an analog signal by the D / A converter 7. The image signal converted into an analog signal is modulated and output as a standard video signal by the encoder 8 and displayed on a monitor (not shown).

The above is the basic operation of the image pickup apparatus, but there are cases where a video signal is input to the image pickup apparatus from the outside and the image pickup signal and the video signal from the outside are switched or combined and used. For example, when a YC separate signal is input from the outside, this input signal is the external input selector switch 1
3A and 13B, of which the color signal is the color decoding unit 1
4, the color difference signals Cr and Cb are decoded. The two types of decoded color difference signals are color difference changeover switches 23A,
23B and the color difference multiplexing switch 15 to be multiplexed into one signal. The luminance signal Y and the color difference signal multiplexed into one line are external signal A / D conversion units 16A and 16B, respectively.
To the digital signal processing unit 6 after being converted into digital data. A / D in the digital signal processing unit 6
Image signal from converter 5 and external signal A / D converter 16
The image signals from A and 16B can be selectively switched, and the same digital signal as the image signal from the A / D conversion unit 5 can be applied to the image signals from the external signal A / D conversion units 16A and 16B. It can be treated.

The external input video signal is a composite signal C
In the case of VS, the luminance signal Y and the color signal C are separated by the YC separation unit 11 and then input to the external input changeover switch 13. In the case of the RGB signal, the RGB / YCrCb conversion unit 12 separates the luminance signal Y from the color signal. After being converted into the signals Cr and Cb, the luminance signal Y is input to the external input changeover switch 13 and the color difference signals Cr and Cb are input to the color difference changeover switches 23A and 23B. Also, there are various switch switching controls, control of digital signal processing modes, and control related to imaging such as auto focus, auto white balance, and auto iris depending on the device, all of which are instructed by the dotted line in the figure of the system control unit 17. Done by. For the functions that can be directly selected by the user, an input instruction can be given from the operation unit 18. In the above-mentioned conventional example, the decoded color difference signals are multiplexed with Cr and Cb into one signal and then A / D converted. However, after the A / D conversion, they are multiplexed or left unmultiplexed. It may be input to the digital signal processing unit 6.

[0008]

However, the above-mentioned conventional example has the following drawbacks. First drawback: When an external video signal is input to an image pickup apparatus that is performing digital signal processing and the same digital processing as that of the image pickup side signal is performed, the image pickup apparatus has external signal A / D conversion units 16A and 16B. A YC separation unit 11, an RGB / YCrCb conversion unit 12, which are equipped with various expensive A / D converters,
It was necessary to provide a video signal decoding circuit including the color decoding unit 14. Further, in order to reduce the cost and reduce the number of A / D converters by multiplexing signals, a multiplexer as a changeover switch which is faster than that is required, and the multiplexer becomes expensive this time.

Second drawback: When inputting an external video signal to the image pickup device, it was necessary to provide a video signal decoding circuit on the image pickup device side, but, of course,
Lens 1, diaphragm 2, image sensor 3, SH / AGC unit 4,
Even in the head-separated image pickup device in which the image pickup unit made of TG9 can be separated from the main body, it is necessary to include the video signal decoding circuit.

An object of the present invention is to eliminate an expensive A / D converter from a decoding circuit for an externally input video signal in an image pickup apparatus which is performing digital signal processing. Another object of the present invention is to provide a head-separated type image pickup device without providing a decoding circuit for an external input video signal.
It is to be able to input a video signal from the outside.

[0011]

According to a first aspect of the present invention, an image pickup means for photoelectrically converting a subject image to output a first image signal, and a video signal input from the outside are used as the first image signal.
Video signal decoding means for converting into the second image signal of the same format as the above image signal, and switching means for switching between the first image signal and the second image signal.

According to a fourth aspect of the present invention, there is provided mounting means for selectively attaching and detaching the image pickup means and the video signal decoding means.

According to a fifth aspect of the present invention, a signal generating means for generating a luminance signal and a color signal from an input video signal, a color decoding means for generating a color difference signal from the color signal, and the luminance signal and the color difference. Signal conversion means for generating an image signal of the same format as the image signal obtained from the image pickup means for photoelectrically converting the subject image based on the signal.

[0014]

According to the first aspect of the invention, the video signal decoding means is provided by converting the first or second image signal obtained from the switching means into a digital signal by the A / D converter and then performing signal processing. It is not necessary to use an expensive A / D converter.

According to the invention of claim 4, the image pickup means or the video signal decoding device can be removably attached to the common attaching means of the image pickup device main body. The input terminal can be omitted.

According to the fifth aspect of the present invention, since the externally input video signal is processed as an analog signal to create a signal of the same format as the imaged signal, this signal is processed by the A / D in the image pickup device. By sending to the converter, it is not necessary to provide an expensive A / D converter inside the video signal decoding device.

[0017]

【Example】

(First Embodiment) FIG. 1 is a block diagram showing the arrangement of an image pickup apparatus capable of inputting an external video signal according to the first embodiment of the present invention. The same parts as those in FIG. 7 are designated by the same reference numerals. . 1 is different from FIG. 7 in that the external signal A / D conversion units 16A and 16B are deleted from the configuration of FIG. 7 and the imaging signal conversion unit 19, the external signal SSG 20, the input signal changeover switch 21, and the SSG changeover switch 22 are added. This is the added point. Here, the image pickup signal converter 19 is a circuit that converts the external input video signal into a signal of the same format as the image pickup signal obtained from the image pickup sensor 3 based on the luminance signal Y and the color difference signals Cr and Cb. As shown in FIG. 2, the image pickup signal converting section 19 includes a luminance constant section 19a, a color difference constant section 19b, an adding section 19c, a subtracting section 19d, and an image pickup signal multiplexing switch 19.
e, S / H unit 19f.

The external signal SSG20 generates a video synchronizing signal and a clock which are synchronized with the external video signal. The input signal changeover switch 21 is a switch that selectively switches between the signal from the SH / AGC unit 4 and the signal from the imaging signal conversion unit 19 and sends the signal to the A / D conversion unit 5. The SSG changeover switch 22 is a switch that operates in synchronization with the changeover of the input signal changeover switch 21 and switches between the SSG 10 and 20 according to the input signal. In addition, 11-15, 19, 2
The video signal decoding means is constituted by the respective units indicated by 0 and 23. Moreover, the signal generating means is configured by the respective units 11 to 13.

Next, a conversion method for converting a video signal into an image signal of the same format as the image pickup signal will be described. When a signal is read out from the image sensor 3 such as a normal CCD, field reading as shown in FIG. 3 is performed. FIG. 3 shows a case where a complementary color filter and a G filter are provided for each pixel on the image pickup surface of the image pickup sensor 3. Read out is A1, A
The charge of each pixel is mixed in a pixel pair such as 2, B1, and B2, and the signal is output for each line in synchronization with the horizontal synchronization signal. Looking at the charge output order on this one line for the A1 line, [Cy + G] [Ye + Mg] [C
The order is y + G] [Ye + Mg]. Looking at the A2 line, [Cy + Mg] [Ye + G] [Cy +
The order is Mg] [Ye + G]. In order to generate the luminance signal Y and the color difference signals Cr and Cb from these signals, the signals may be processed as follows. That is, Y = {[Cy + G] + [Ye + Mg]} × 1/2 = 1/2 {2R + 2G + 2B} Cr = [Ye + Mg]-[Cy + G] = 2R-G-Cb = [Ye + G]-[Cy + Mg] =-{ 2B-G} ... (Equation 1) is processed.

On the other hand, in order to convert the external input video signal into the image pickup signal format, the input signals Y, Cr,
From Cb to [Cy + G] [Yc + Mg] [Ye + G] [C
y + Mg] may be generated. That is, [Cy + G] = Y− [R−Y] × 1/2 [Ye + Mg] = Y + [R−Y] × 1/2 [Cy + Mg] = Y + [B−Y] × 1/2 [Ye + G] = Y -[B-Y] × 1/2 ... Generated by the processing of (Equation 2). However, Cr = RY, Cb =
Let BY.

Next, only the video signal decoding means different from the conventional example in the operation for performing the above processing will be described. The luminance signal Y of the external input video signal passes through the external input changeover switch 13 and is input to the imaging signal conversion unit 19 and also to the external signal SSG20. The external signal SSG20 separates the sync signal from the luminance signal Y and generates a video sync signal and a clock that are synchronized with the external input video signal. Color difference signals Cr and C of the external input video signal
The signal b is passed through the color difference changeover switches 23A and 23B, multiplexed by the color difference multiplex switch 15 into one signal, and then input to the imaging signal conversion unit 19. At this time, the switching timing for multiplexing is synchronized with the horizontal synchronizing signal HD generated by the external signal SSG20, as shown in FIG. As a result, a color difference multiplexed signal in which Cr and Cb alternately (line-sequentially) appear on one signal line at each horizontal line timing is obtained. The image pickup signal conversion unit 19 adds and subtracts the luminance signal Y and the color difference signals multiplexed for each 1H to obtain [Cy + G], [Ye + M].
g], [Cy + Mg], and [Ye + G] are generated.

Next, as shown in FIG. 5, these signals are changed to H
It is multiplexed into one signal by a switching clock having a frequency much higher than D. As a result, there is a certain 1 on one signal.
During the H period, [Cy + G] and [Ye + Mg] appear alternately (dot-sequentially) in synchronization with the clock at the time of multiplexing.
During the H period, S / H in which [Cy + Mg] and [Ye + G] appear alternately (dot-sequentially) in synchronization with the clock at the time of multiplexing.
An output signal is obtained. This [Cy + G] and [Ye + M
g] and the periods containing [Cy + Mg] and [Ye + G] appear alternately (line-sequentially) in synchronization with HD. The format of this S / H output signal is the image sensor 3
The format is the same as the image pickup signal which is picked up by and is output from the SH / AGC unit 4. That is, the image signal output from the image pickup signal conversion unit 19 is selected by the input signal changeover switch 21, and thus the same signal processing as the image pickup signal from the SH / AGC unit 4 is performed. Therefore, the A / D conversion unit 5 common to the image signal and the image pickup signal is used.

Next, the image pickup signal converter 19 will be described with reference to FIG. The luminance signal is amplified or attenuated by the luminance constant section 19a, and the multiplexed color difference signal is amplified or attenuated by the color difference constant section 19b at a predetermined magnification. A combination of constants α and β that determines the magnification is determined by a constant control signal, for example, from the conversion equation (Equation 2) described above, when the signal gain to be output is 1, [×
1, x 1/2], and when you want to set the gain to 2,
2, x1]. Of course, the desired gain can be obtained by freely changing the settings. The amplified or attenuated luminance signal and the multiplexed color difference signal are added by the adder 19c to generate [Ye + Mg] and [Cy + Mg]. In addition, since the subtraction unit 19d subtracts,
[Cy + G] and [Ye + G] are generated.

[Ye + Mg], [Cy + M]
[g], [Cy + G], and [Ye + G] are point-sequentially multiplexed into one signal by the imaging signal multiplexing switch 19e. The timing of the switching to be multiplexed at this time is the clock generated by the timing generator 9, and is synchronized with the HD generated by the external signal SSG20. This clock is, for example, 4 fsc (fsc is a color sub-carrier frequency, and in the case of an NTSC signal, 14,318).
It is 18 MHz. ). This frequency is the frequency of the CCD operation clock when a 400,000 pixel CCD is used for the image sensor 3. If the image sensor is replaced and the operating clock changes, it is necessary to match the frequency.

Next, the S / H unit 19f samples and holds (S / H) the signals multiplexed by the imaging signal multiplexing switch 19e. The timing of this S / H is equal to the switching frequency of the imaging signal multiplexing switch 19e. The S / H image signal is output to the input signal changeover switch 21 as a signal having the same format as the image pickup signal from the SH / AGC unit 4.

As described above, according to the present embodiment, when the video signal is decoded, the video signal is not converted into the digital signal as in the conventional case, but is converted into the image signal format of the image sensor. In FIG. 7, the expensive external signal A / D converters 16A and 16B conventionally required can be omitted, and a cheaper video signal decoding circuit can be realized.

(Second Embodiment) FIG. 6 is a block diagram showing the arrangement of a head separation type image pickup apparatus according to the second embodiment of the present invention. 6 is composed of the same blocks as in FIG. 1 according to the first embodiment, but the video signal decoding portion is configured as a separate device, and this portion can be attached and detached in response to a user's request. .

In FIG. 6, the whole can be divided into three parts, an image pickup part (head part) A, a main body control part B and a video signal decoding device C. The image pickup unit A and the main body control unit B are connected via a board to board or a cable. When inputting an external video signal to this head-separated image pickup device, it is usually necessary to provide an external video signal decoding circuit and an external signal input terminal inside the image pickup device as in the first embodiment. On the other hand, in this embodiment, an external video signal decoding apparatus C having a function of converting a video signal into an image pickup signal format according to the present invention is provided between the head (image pickup unit A) and the main body of the head separated type image pickup apparatus. By inserting and connecting, an external video signal can be taken in. By using the external video signal decoding device C as described above, the video signal decoder circuit and the dedicated input terminal for the external signal can be omitted from the imaging device main body, and the cost and size of the basic structure of the imaging device can be reduced. realizable.

The mounting means is constituted by the portions where the switches 21 and 22 and their terminals are provided. Also,
The switches 21 and 22 may be automatically switched when the image pickup unit A or the video signal decoding device B is selectively attached and detached via the attaching means.

[0030]

As described above, according to the invention of claim 1, since the video signal decoding means for converting the video signal into the image pickup signal format is provided, in the image pickup apparatus for performing the digital signal processing, An expensive A / D converter can be eliminated from the decoding circuit of the external input video signal, and the cost of the device can be reduced.

According to the invention of claim 4, in the head-separated type image pickup device, a video signal decoding device capable of converting a video signal into a signal of an image pickup signal format is provided between the head (image pickup section) and the main body. Since it is configured such that it can be attached and detached via the common device means, it is possible to omit the input terminal from the image pickup device main body to the video signal decoder circuit and the external signal, and it is possible to achieve cost reduction and downsizing of the basic configuration of the image pickup device. it can.

Further, according to the invention of claim 5, the video signal decoding device is constructed without using an expensive A / D converter, so that the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an image pickup apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing an internal configuration of an image pickup signal conversion unit in the first embodiment.

FIG. 3 is a configuration diagram showing a color configuration of a complementary color mosaic filter of a CCD.

FIG. 4 is a timing chart showing generation of a color difference multiplexed signal by a color difference changeover switch.

FIG. 5 is a timing chart showing generation of an image pickup signal format signal by an image pickup signal multiplexing switch.

FIG. 6 is a block diagram showing a configuration of an image pickup apparatus according to a second embodiment of the present invention.

FIG. 7 is a block diagram showing a configuration of a conventional image pickup apparatus.

[Explanation of symbols]

 1 Optical Lens 2 Aperture 3 Image Sensor 4 SH / AGC Section 9 Timing Generator 11 YC Separation Section 12 RGB / YCrCb Conversion Section 13A, 13B External Input Changeover Switch 14 Color Decoding Section 15 Color Difference Multiplexing Switch 17 System Control Section 19 Imaging Signal Conversion Part 19a Luminance constant part 19b Color difference constant part 19c Addition part 19d Subtraction part 19c Imaging signal multiplexing switch 19f S / H part 20 External signal SSG 21 Input signal changeover switch 22 SSG changeover switch 23A, 23B Color difference changeover switch

Claims (6)

[Claims] 1. An image pickup means for photoelectrically converting a subject image to output a first image signal, and a video signal input from the outside to a second image signal of the same format as the first image signal. An image pickup apparatus comprising video signal decoding means and switching means for switching the first image signal and the second image signal. 2. The video signal decoding means, a signal generating means for generating a luminance signal and a color signal from the video signal input from the outside, a color decoding means for generating a color difference signal from the color signal, The image pickup apparatus according to claim 1, further comprising a signal conversion unit that generates the second image signal based on a luminance signal and a color difference signal. 3. The signal converting means adds a constant means for multiplying the luminance signal and the color difference signal by a constant and an addition for generating a signal of “Yc + Mg” or “Cy + Mg” from the luminance signal and the color difference signal. Means, subtraction means for generating a "Cy + G" or "Yc + G" signal from the luminance signal and the color difference signal, and an output of the addition means and an output of the subtraction means are multiplexed into one signal. The image pickup apparatus according to claim 2, further comprising: a signal multiplexing unit; and a sample and hold unit that samples and holds the output of the signal multiplexing unit. 4. The image pickup apparatus according to claim 1, further comprising a mounting means for selectively removably mounting the image pickup means and the video signal decoding means. 5. A signal generating means for generating a luminance signal and a color signal from an input video signal, a color decoding means for generating a color difference signal from the color signal, and an object based on the luminance signal and the color difference signal. A video signal decoding device comprising: a signal conversion unit that generates an image signal of the same format as an image signal obtained from an image pickup unit that photoelectrically changes an image. 6. The signal converting means adds a constant means for multiplying the luminance signal and the color difference signal by a constant and an addition for generating a “Ye + Mg” or “Cy + Mg” signal from the luminance signal and the color difference signal. Means, subtraction means for generating a "Cy + G" or "Ye + G" signal from the luminance signal and the color difference signal, and the output of the addition means and the output of the subtraction means are multiplexed into one signal. 6. The video signal decoding apparatus according to claim 5, further comprising signal multiplexing means and sample and hold means for sampling and holding the output of the signal multiplexing means.