JPH0213180A - Video camera - Google Patents

Abstract

PURPOSE:To prevent deficiency of sharpness correction quantity with a decreased gain or deterioration in the S/N with too much sharpness caused with an increased gain by providing a switch means controlling the gain of an input video signal and switching the sharpness correction in interlocking with the switch means. CONSTITUTION:The gain of an amplifier 5 is switched into 3 stages such as 0dB, 9dB and 18dB by a control signal S1 from a controller 6. The gain is set by a switch 14. The sharpness correction is switched in interlocking with the switch 14. With the gain of a luminance signal and a chrominance signal increased, then the sharpness correction quantity is decreased and with the gain of a luminance signal and a chrominance signal decreased, then the sharpness correction quantity is increased. Thus, the deterioration in the S/N is prevented when the gain is increased and no deficiency in the sharpness correction is avoided when the gain is decreased thereby obtaining a sharp pattern.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a video camera.

[Summary of the Invention] The present invention provides a video camera in which a switch means for controlling the gain of an input video signal is provided, and the amount of sharpness correction is switched in conjunction with the switch means, so that when the gain is increased, This is designed to deal with the deterioration of the S/N ratio due to excessive sharpness that occurs, and the lack of sharpness correction when the gain is lowered.

[Conventional technology]

Video cameras have been developed that are compatible with a recording method that increases the carrier frequency of a luminance signal to improve horizontal resolution. With this recording method, a horizontal resolution of 500 lines or more can be achieved, and by separating the luminance signal Y and chroma signal C, interference between the luminance signal Y and chroma signal C can be prevented, resulting in higher image quality. can be measured.

In a video camera that can perform such high-quality recording, the camera section and the deck section can be separated to improve operability. In addition, in order to take advantage of the characteristics of a video camera that can perform such high-quality recording, various manual switches are provided to enable the video camera to always record optimal images in all recording conditions.

For example, such a camera-integrated VTR is provided with a switch for adjusting the gain, and this gain changeover switch changes the gain to, for example, OdB or 9dB.

It is said that it is possible to switch to 18 dB.

[Problems to be Solved by the Invention] As described above, some video cameras for recording high quality images have conventionally been provided with a gain changeover switch. However, with conventional video cameras like this, the sharpness correction amount cannot be changed along with the gain, so when the gain is changed, the S/N ratio deteriorates or sufficient sharpness correction cannot be obtained, resulting in blurred images. Something like this happens.

Therefore, an object of the present invention is to provide a video camera that can switch the amount of sharpness correction depending on the gain.

[Means to solve the problem]

The present invention is a video camera characterized in that a switch means for controlling the gain of an input video signal is provided, and a means for switching the sharpness correction amount in conjunction with the switch means is provided.

[Function] The sharpness correction amount is switched in conjunction with the switch 14 that switches the gain. As a result, when the gain of the luminance signal and the gain of the chroma signal are increased, the sharpness correction amount is decreased, and when the gain of the luminance signal and the gain of the chroma signal are decreased, the sharpness correction amount is increased.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the overall configuration of a video camera to which the present invention is applied. In FIG. 1, an image received by lens l is transmitted to a CCD via a prism (not shown).
The light is received by the image sensor 2, and the CCD↑most image element 3
The light is received by A CCD image sensor 2 is provided to obtain a luminance signal Y. The CCD image sensor 3 receives a chroma signal C
It is designed to obtain.

The output of the CCD image sensor 2 is sampled and held by a sample and hold circuit 4, and the output of this sample and hold circuit 4 is supplied to an amplifier 5. The gain of the amplifier 5 is determined by the control signal S1 from the controller 6, for example, Odb,
It is said that it is possible to switch between three levels: 9dB and 18dB. Gain settings are made by switch 14.

After the output of the amplifier 5 is supplied to a gamma correction circuit 7 and subjected to gamma correction, it is supplied to an H-direction sharpness correction circuit 9 via a low-pass filter 8 for noise removal, and also to a direction sharpness correction circuit 10. Ru. H
The horizontal sharpness correction circuit 9 emphasizes the contour in the horizontal direction. The vertical sharpness correction circuit 10 emphasizes the edges in the vertical direction. The sharpness correction circuit 9 in the H direction receives a control signal S from the controller 6.
3, the correction amount can be changed according to the gain set by the switch 14.

The output of the H direction sharpness correction circuit 9 and the output of the ■ direction sharpness correction circuit 10 are supplied to an addition circuit 11. The adder circuit 11 outputs signals whose edges are emphasized in the horizontal and vertical directions. This addition circuit 11
The output of the synchronizing signal adding circuit 12 is supplied to the synchronizing signal adding circuit 12. This synchronizing signal adding circuit 12 adds a synchronizing signal to the luminance signal output from the adding circuit 11. Then, a luminance signal to which this synchronization signal is added is output from the luminance signal output terminal 13.

On the other hand, the output of the CCD image sensor 3 is supplied to a sample and hold circuit 15, and the output of the CCD↑most image element 3 is sampled and held. The output of the sample hold circuit 15 is supplied to an amplifier 16. The gain of the amplifier 16 can be switched to three levels by operating a switch 14 in response to a control signal S2 from the controller 6.

The output of the amplifier 16 is connected to the sample and hold circuits 17A and 17.
B, 17C. Sample hold circuit 17A
A color signal R is obtained from the output of the sample hold circuit 1.
A color signal G is obtained from the output of the sample hold circuit 17B, and a color signal B is obtained from the output of the sample hold circuit 17C.

Three primary color signals R, G, and B output from the sample and hold circuits 17A, 17B, and 17C are supplied to a white balance adjustment circuit 18. The white balance adjustment circuit 18 includes an amplifier 31A that amplifies the color signal R, an amplifier 31B that amplifies the color signal G, and an amplifier 31C that amplifies the color signal B.
It consists of The gain of amplifiers 31A to 31C is
White balance adjustment is performed by adjusting the signal level of color signal G as a reference.

Amplifiers 31A and 31B of white balance adjustment circuit 18
, 31C respectively output three primary color signals R, G, B.
are supplied to gamma correction circuits 19A and 198119C, respectively. The outputs of the gamma correction circuits 19A, 19B, and 19C are supplied to the matrix circuit 20.

The matrix circuit 20 forms color difference signals (R-Y) and (B-Y) from the three primary color signals R, G, and B. These color difference signals (R-Y) and (B-Y) are passed through the low-pass filter 21.
It is supplied to the modulation circuit 22 via A and 21B, respectively.

The modulation circuit 22 performs quadrature two-phase modulation on the color difference signals (R-Y) and (B-Y) to form a chroma signal C. This chroma signal C is taken out from the chroma signal output terminal 23.

As mentioned above, this video camera is provided with a switch 14 that changes the gain of the video signal, and when the gain is changed with this switch 14, in conjunction with this,
The sharpness correction amount can be changed. This will be explained.

As shown in Figure 2, switch 1 for switching gain
4 switches the voltage applied to the A/D converter 52, and data corresponding to this voltage is sent to the A/D converter 52.
is output from. The output of this A/D converter 52 is supplied to the controller 6.

That is, when the switch 11 is switched to the terminal 11A side, the gain is set to, for example, OdB, and the switch 11 is switched to the terminal 11A side.
is switched to the terminal 11B side, the gain becomes, for example, 9d.
When the switch 11 is switched to the terminal 11C side, the gain is switched to, for example, 18 dB. When the switch 11 is switched to the terminal 11A side, the A/D converter 52 is given the GND level. When the switch 11 is switched to the terminal 11B side, the voltage applied to the power supply terminal 51 is connected to the resistors 53 and 5.
The voltage obtained by dividing the voltage by 4 is applied to the A/D converter 52. When the switch 11 is switched to the terminal 11C side, the voltage applied to the power supply terminal 51 is divided by the resistors 53 and 55, and the voltage obtained is applied to the A/D converter 52.
is supplied to By setting the resistance values of the resistor 54 and the resistor 55 appropriately, when the switch 11 is switched,
A voltage that changes in steps is obtained. Data corresponding to this voltage is given to controllers 1 to 6.

The controller 6 outputs control data according to this data, and this data is supplied to the electronic volume circuit 57. The electronic volume circuit 57 is a D/A converter that generates an analog control voltage corresponding to a control signal from the controller 6. This electronic volume circuit 5
The output of 7 is supplied to the amplifier 5 and the amplifier 16 as gain control signals S1 and S2, and is also supplied to the H-direction sharpness correction circuit 9 as a sharpness correction amount control signal S3. Thereby, by operating the switch 11, the gain of the luminance signal and the gain of the chroma signal are switched, and in conjunction with this, the sharpness correction amount is switched.

That is, when the gain of the luminance signal and the gain of the chroma signal are increased, the sharpness correction amount is decreased, and when the gain of the luminance signal and the gain of the chroma signal are decreased, the sharpness correction amount is increased. Thereby, when the gain is increased, it is possible to prevent the S/N ratio from deteriorating, and when the gain is decreased, the sharpness correction amount is not insufficient, and a clear screen can be obtained.

In the embodiment described above, only the horizontal sharpness correction amount may be changed in accordance with the gain, or the vertical sharpness correction amount may also be changed in accordance with the gain.

〔Effect of the invention〕

According to this invention, the sharpness correction amount is switched in conjunction with the switch that switches the gain. As a result, when the gain of the luminance signal and the gain of the chroma signal are increased, the sharpness correction amount is decreased, and when the gain of the luminance signal and the gain of the chroma signal are decreased, the sharpness correction amount is increased. Therefore, when the gain is increased, it is possible to prevent the SZN ratio from deteriorating, and when the gain is decreased, the sharpness correction amount is not insufficient, and a clear screen can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a block diagram used to explain the embodiment of the invention. Explanation of main symbols in the drawings 2.3: CCD image sensor, 5. IS: Amplifier. 6: Controller, 9: H direction sharpness correction circuit,
57: Electronic volume circuit.

Claims (1)

[Claims] A video camera comprising: switch means for controlling the gain of an input video signal; and means for switching a sharpness correction amount in conjunction with the switch means.