JPH11266442A - Video signal communication equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce an influence due to the noise received during transmission by encoding a video signal so that the contrast ratio of the signal is 100% in every field and transmitting it and decoding it to the original contrast after reception. SOLUTION: The video signal photographed by a video camera 2 has the video level (luminance) adjusted to a certain value by an AGC 3 and is encoded by an encoder 8 so that the contrast ratio of the signal is 100% for every field, and a signal corresponding to the coefficient of encoding is transmitted to a decoder 9. The video signal outputted from the encoder 8 is transmitted by a transmitter 4 and is received by a receiver 6, and the decoder 9 decodes the contrast ratio of the video signal to an original value in accordance with the signal indicating the coefficient of encoding of the contrast ratio received from the encoder 8, and it is evaluated by a TV monitor 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal communication device for transmitting an image signal captured by a video camera to a television monitor.

[0002]

2. Description of the Related Art FIG. 7 shows an example of a conventional video signal communication apparatus. This is "Image Engineering" P. FIG. 6 schematically shows “Application of Shannon's communication model (a) to image engineering (b)” shown as an explanation of the hardware configuration of the communication apparatus in FIG. An object 2, a video camera 3, an AGC amplifier 4, a video signal transmitting device 5, a video signal communication channel 6, a video signal receiving device 6, and a television monitor 7 are shown. Incidentally, the AGC amplifier 3 is generally provided in the video camera 2 today.

Next, the operation will be described. Conventionally, an image of a subject 1 is photographed by a video camera 2, and a video signal obtained here is adjusted by an AGC amplifier 3 to adjust a video level (luminance) to a constant value, if necessary, and then transmitted by a transmission device 4. , Transmitted by the communication channel 5, received by the receiving device 6, and evaluated by the television monitor 7.

[0006] Here, the video level is adjusted by the AGC amplifier 3. However, regarding the contrast ratio of the video signal, the video signal is transmitted as it is captured by the video camera 2.

[0005]

Since the conventional video signal communication apparatus is configured as described above, when the contrast ratio of the original video signal is low, that is, when an image of an airy vehicle or the like is photographed, There has been a problem that it is susceptible to the effect of noise mixed during signal transmission.

The present invention has been made to solve such a problem, and encodes a video signal so that the contrast ratio becomes 100% for each field, transmits and transmits the video signal, and after receiving, decodes the video signal to the original contrast ratio. Therefore, it is an object of the present invention to reduce the influence of noise received during transmission.

[0007]

A video signal communication apparatus according to a first aspect of the present invention encodes a video signal whose video level is adjusted to a constant value by an AGC amplifier so that a contrast ratio becomes 100% for each field. At the same time, a signal whose level changes in accordance with the encoding coefficient is transmitted in parallel with the video signal, and the receiving side compares this signal with a reference value to decode the contrast ratio to the original state, and during transmission of the signal. At the same time.

A video signal communication apparatus according to a second aspect of the present invention encodes a video signal whose video level is adjusted to a constant value by an AGC amplifier so that a contrast ratio becomes 100% for each field, and simultaneously encodes the video signal. After the level of the blanking signal is increased or decreased according to the coefficient of transmission, transmission and reception, the contrast ratio is decoded to an original state by comparing the blanking signal with a reference value on the receiving side, and the signal is decoded. The noise received during transmission is reduced at the same time.

A video signal communication apparatus according to a third aspect of the present invention encodes a video signal whose video level is adjusted to a constant value by an AGC amplifier so that a contrast ratio becomes 100% for each field, and simultaneously encodes the video signal. A signal that changes in level according to the coefficient of the video signal is superimposed on the front porch of the blanking interval of the video signal and transmitted, and the contrast ratio is decoded to the original state by comparing this signal with a reference value on the receiving side, The noise received during the transmission of the signal is also reduced at the same time.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a diagram showing Embodiment 1 of the present invention, in which 1 is a subject,
Reference numeral 2 denotes a video camera that converts an optical signal of a subject into a video signal, 3 denotes an AGC amplifier that controls the level of a video signal output from the video camera to a constant value, and 8 denotes an AGC amplifier.
An encoder that encodes a contrast ratio indicating the brightness of a subject, which is included in the video signal output from the amplifier in the form of a high or low signal level, to 100%, and outputs an encoding coefficient of the contrast ratio as an electric signal. A transmitting device for transmitting a video signal output from the encoder 8, a communication channel 5 for a video signal, a receiving device 6 for a video signal, and a contrast ratio 9 of a received video signal according to an output signal of the encoder 8. And a television monitor 7 for evaluating an image.

FIG. 2 is a diagram showing the internal configuration of the encoder 8. In FIG. 2, reference numeral 14 denotes a synchronization separation circuit for separating a synchronization signal from a video signal output from the AGC amplifier 3, and reference numeral 15 denotes a video signal output from the synchronization separation circuit 14. Amplifier 16 amplifies the contrast ratio of the video signal, 16 detects a white level (the highest level portion) of the video signal output from the video amplifier 15, and outputs a comparison value with an internal reference value. Value (highest value) of the output value of the heater 16
And a peak hold circuit for feeding back the signal to the AGC input of the video amplifier 15. A peak detection circuit 16 detects the black level (lowest level portion) of the video signal output from the video amplifier 15 and compares the value with the internal reference value. A peak hold circuit 19 and a comparator to be output to a receiver,
Reference numeral 9 denotes a peak hold circuit that holds the peak value (minimum value) of the output value of the comparator 18 and feeds it back to the negative input of the video amplifier 15, and reference numeral 20 denotes a synchronous combination that combines a video signal output from the video amplifier 15 with a synchronous signal. Circuit.

Next, the operation will be described. The video signal captured by the video camera 2 is adjusted to a constant video level (brightness) by the AGC amplifier 3. Up to this point, it is equivalent to the conventional communication device, and furthermore, the encoder 8
The contrast ratio of the signal to 10 for each field.
The encoding is performed to 0%, and at the same time, a signal corresponding to the encoding coefficient is transmitted to the decoder 9. FIG. 2 shows this encoder 8
FIG. 3 is a diagram showing the internal configuration of a video signal input from an AGC amplifier 3, and the video signal is input to a video amplifier 15 after the sync signal is separated by a sync separation circuit 14. Video amplifier 15
At the output end of the video signal, the comparator 16 detects the white level (highest level part) of the video signal and the comparator 18 detects the black level (lowest level part) of the video signal. The peak value in one field is determined by the AGC of the video amplifier 15 by the circuits 17 and 19.
By feeding back to the input, the contrast ratio, that is, the difference between the white level and the black level is encoded to 100%. Thereafter, the synchronizing signal is again synthesized with the video signal by the synchronizing synthesizing circuit 20 and output to the transmitter 4. The comparison value between the black level output from the peak hold circuit 19 and its reference value is transmitted to the receiver 6 as an encoding coefficient. The video signal output from the encoder 8 is transmitted by the transmitting device 4, transmitted by the communication channel 5, received by the receiving device 6, and the decoder 9 receives the video signal according to the signal indicating the coefficient of the contrast ratio encoding received from the encoder 8. Of the TV monitor 7 to the original value.
Assess by

Embodiment 2 FIG. FIG. 3 is a diagram showing Embodiment 2 of the present invention, in which 1 is a subject, 2 is a video camera that converts an optical signal of the subject into a video signal, 3
Is an AGC amplifier for controlling the level of a video signal output from the video camera to a constant value, and 10 is a contrast ratio indicating the contrast of the subject, which is included in the video signal output from the AGC amplifier in the form of the signal level. 100
%, An encoder for increasing or decreasing the level of the blanking signal of the transmission video signal in accordance with the coefficient of the encoding of the contrast ratio, 4 a transmission device for transmitting the video signal output from the encoder 10, 5 a video signal 6 is a video signal receiving device, 11 is a decoder for decoding the contrast ratio of the received video signal into the contrast ratio of the original signal according to the level of the blanking signal, and 7 is a television monitor for evaluating an image. .

FIG. 4 is a diagram showing the internal configuration of the encoder 10. In FIG. 4, reference numeral 14 denotes a synchronization separation circuit for separating a synchronization signal from a video signal output from the AGC amplifier 3, and reference numeral 15 denotes a video signal output from the synchronization separation circuit 14. Amplifier 16 amplifies the contrast ratio of the video signal, 16 detects a white level (the highest level portion) of the video signal output from the video amplifier 15, and outputs a comparison value with an internal reference value. A peak hold circuit which holds the peak value (highest value) of the output value of the amplifier 16 and feeds it back to the AGC input of the video amplifier 15, and 18 a black level (lowest level portion) of the video signal output from the video amplifier 15 A comparator that detects and outputs a comparison value with an internal reference value to a peak hold circuit 19 and a synchronous synthesis circuit 21. A peak hold circuit that holds the peak value (minimum value) of the output value of the comparator 18 and feeds it back to the minus input of the video amplifier 15. A peak synthesis circuit 21 combines a video signal output from the video amplifier 15 with a synchronizing signal, and 18 is a synchronous synthesizing circuit for increasing or decreasing the level of a blanking signal in accordance with the output value of 18.

Next, the operation will be described. The video signal captured by the video camera 2 is adjusted to a constant video level (brightness) by the AGC amplifier 3. Up to this point, it is equivalent to the conventional communication device, and furthermore, the encoder 1
0 sets the signal contrast ratio to 1 for each field.
At the same time, the blanking signal is increased or decreased according to the encoding coefficient. FIG. 4 is a diagram showing the internal configuration of the encoder 10. The video signal input from the AGC amplifier 3 is input to the video amplifier 15 after the sync signal is separated by the sync separation circuit 14. At the output terminal of the video amplifier 15, the comparator 16 detects the white level (highest level part) of the video signal and the comparator 18 detects the black level (lowest level part) of the video signal.
Each of the peak hold circuits 17 and 1 is compared with a reference value.
9, the peak value in one field is set to A of video amplifier 15
By feeding back to the GC and -inputs, the contrast ratio, ie, the difference between the white level and the black level, is encoded to 100%. Further, the comparison value between the black level output from the peak hold circuit 19 and the reference value is output to the synchronization synthesizing circuit 21 as an encoding coefficient, and becomes the level of the blanking signal when synchronizing the video signal with the synchronization signal again. To reflect. The video signal output from the encoder 10 is transmitted by the transmitting device 4, transmitted by the communication channel 5, received by the receiving device 6, and the decoder 11 compares the blanking signal of the received video signal with a reference value to compare the contrast ratio of the signal. Is restored to the original value, the blanking signal is restored to the reference level, and the TV monitor 7 evaluates the blanking signal.

Embodiment 3 FIG. 5 is a diagram showing Embodiment 3 of the present invention, in which 1 is a subject, 2 is a video camera that converts an optical signal of the subject into a video signal, 3
Is an AGC amplifier for controlling the level of the video signal output from the video camera to a constant value, and 12 is a contrast ratio indicating the contrast of the subject, which is included in the video signal output from the AGC amplifier in the form of the signal level. 100
%, And a transmission device for transmitting a video signal output from the encoder 12, an encoder for transmitting a video signal output from the encoder 12, and an encoder for superimposing a signal corresponding to the encoding coefficient of the contrast ratio on a front porch during a blanking period of the video signal. Is a video signal communication path, 6 is a video signal receiving apparatus, 13 is a decoder that separates a signal superimposed on a front porch during a blanking period of a received video signal and decodes the signal into a contrast ratio of an original signal, 7 Is a television monitor for evaluating images.

FIG. 6 is a diagram showing the internal configuration of the encoder 12. In FIG. 6, reference numeral 14 denotes a synchronization separation circuit for separating a synchronization signal from a video signal output from the AGC amplifier 3, and reference numeral 15 denotes a video signal output from the synchronization separation circuit 14. Amplifier 16 amplifies the contrast ratio of the video signal, 16 detects a white level (the highest level portion) of the video signal output from the video amplifier 15, and outputs a comparison value with an internal reference value. A peak hold circuit which holds the peak value (highest value) of the output value of the amplifier 16 and feeds it back to the AGC input of the video amplifier 15, and 18 a black level (lowest level portion) of the video signal output from the video amplifier 15 A comparator that detects and outputs a comparison value with an internal reference value to a peak hold circuit 19 and a synchronous synthesis circuit 22. A peak hold circuit 22 that holds the peak value (minimum value) of the output value of the comparator 18 and feeds it back to the negative input of the video amplifier 15. The peak hold circuit 22 combines the video signal output from the video amplifier 15 with a synchronizing signal, and Is a synchronous synthesizing circuit that superimposes a signal indicating the output value on the front porch during a blanking period of a video signal.

Next, the operation will be described. The video signal captured by the video camera 2 is adjusted to a constant video level (brightness) by the AGC amplifier 3. Up to this point, it is equivalent to the conventional communication device, and furthermore, the encoder 1
2, the contrast ratio of the signal is 1 for each field.
At the same time, a signal whose level changes in accordance with the encoding coefficient is superimposed on the front porch during the blanking period of the video signal. FIG.
5 is a diagram showing the operation of the video signal input to the video amplifier 15 after the video signal input from the AGC amplifier 3 is separated by the sync separation circuit 14. Video amplifier 1
5, the comparator 16 detects the white level (highest level part) of the video signal and the comparator 18 detects the black level (lowest level part) of the video signal. Hold circuits 17 and 19
The peak value in one field is determined by AG of the video amplifier 15.
By feeding back to the C and-inputs, the contrast ratio, ie, the difference between the white level and the black level, is encoded to 100%. The comparison value between the black level output from the peak hold circuit 19 and the reference value is output to the synthesizing circuit 22 as an encoding coefficient, and blanking of the video signal is performed when the synchronizing signal is synthesized with the video signal again. Superimpose on the front porch of the period. The video signal output from the encoder 12 is transmitted by the transmitter 4, transmitted by the communication path 5, received by the receiver 6, and normalized by the decoder 13 to the contrast ratio superimposed on the front porch during the blanking period of the video signal. Is detected, the contrast ratio of the video signal is decoded to the original value, and evaluated by the television monitor 7.

[0019]

According to the first aspect of the present invention, the signal is always transmitted in a state where the video contrast of each field is 100%. Therefore, when the contrast ratio of the original video signal is low, the signal is transmitted during the signal transmission. This has the effect of reducing the influence of the received noise and transmitting a good video signal with less noise.

According to the second invention, a signal for indicating a coefficient of contrast ratio encoding is superimposed on a blanking signal in order to obtain the same effect as the first invention. There is an effect that there is no need to prepare a transmission path.

According to the third aspect of the invention, in order to obtain the same effect as the first aspect of the invention, a signal for indicating a coefficient for encoding the contrast ratio is superimposed on the front porch during the blanking period of the video signal. Therefore, there is an effect that there is no need to prepare a separate transmission path from the video signal,
Since there is no need to change the level of the blanking signal, a conventional communication device and a part of a communication path can be used.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing an internal configuration of an encoder 8 shown in FIG.

FIG. 3 is a diagram showing a second embodiment of the present invention.

4 is a diagram showing an internal configuration of the encoder 10 shown in FIG.

FIG. 5 is a diagram showing a third embodiment of the present invention.

FIG. 6 is a diagram showing an internal configuration of the encoder 12 shown in FIG.

FIG. 7 is a diagram showing an example of a conventional video signal communication device.

[Explanation of symbols]

1 subject, 2 video camera, 3 AGC amplifier, 4
Transmission device, 5 communication path, 6 reception device, 7 television monitor, 8 encoder, 9 decoder, 10 encoder, 11 decoder, 12 encoder, 13 decoder, 14 sync separation circuit, 15 video amplifier, 16
Comparator, 17 peak hold circuit, 18 comparator, 1
9 Peak hold circuit, 20 Synchronous synthesis circuit, 21
Synchronous synthesis circuit, 22 Synchronous synthesis circuit.

Claims (3)

[Claims] 1. A video signal communication apparatus for transmitting a signal of an image captured by a video camera to a television monitor, wherein the video signal output from the video camera indicates the brightness of a subject included in the form of a signal level. Means for encoding the contrast ratio to 100%, means for outputting the encoding coefficient of the contrast ratio as an electric signal, and converting the video signal on the television monitor side to the contrast ratio of the original signal by a signal indicating the rate of increase of the contrast ratio. A video signal communication device, comprising: decoding means. 2. A video signal communication apparatus for transmitting a signal of an image photographed by a video camera to a television monitor, wherein the video signal output from the video camera indicates the brightness of a subject included in the form of a signal level. Means for encoding the contrast ratio to 100%; means for increasing or decreasing the level of the blanking signal of the transmission video signal in accordance with the coefficient of encoding the contrast ratio; A video signal communication apparatus comprising: means for decoding the original signal into a contrast ratio according to the level of the original signal; and means for restoring the blanking signal after reception to a reference level. 3. A video signal communication apparatus for transmitting a signal of an image taken by a video camera to a television monitor, wherein the video signal output from the video camera indicates the brightness of a subject included in the form of a signal level. Means for encoding the contrast ratio to 100%; means for superimposing a signal corresponding to the encoding coefficient of the contrast ratio on the front porch during the blanking period of the video signal;
Means for decoding the contrast ratio of the video signal on the television monitor side into a contrast ratio of an original signal in accordance with a signal superimposed on a front porch during a blanking period of the video signal. apparatus.