JPH0415675B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high-definition television transmission method for transmitting a high-definition color television signal in which both the luminance signal and the chrominance signal are wideband, and in particular, the present invention relates to a high-definition television transmission method that transmits a high-definition color television signal in which both the luminance signal and the chrominance signal are wideband. However, it maintains high quality and can be transmitted over a single line.

Conventional methods for transmitting high-definition color television signals with broadband brightness and color signals include a transmission method that transmits a composite color image signal called the HLO-PAL method, and a transmission method called the YC separation FM method. It was being considered. The former frequency multiplexes the color signal information into the high frequency range of the luminance signal, and the frequency band extends to 80MHz, and the color signal information is concentrated in the high frequency range of the baseband image signal. It is essentially unsuitable for application to FM broadcasting used in satellite broadcasting. On the other hand, the latter method separates the luminance signal and color signal and transmits them through separate lines, and has the disadvantage of using two transmission lines.

Therefore, as a method for transmitting high-definition color television signals by broadcasting satellites, the so-called TCI transmission method, which compresses the time axis of each luminance signal and chrominance signal and then transmits them via time division multiplexing, has been adopted and studied in recent years. ing. however,
In conventional TCI transmission methods, the frequency band of the baseband image signal is expanded, or in order to suppress the expansion of the frequency band, the frequency band of the color signal is narrower than a predetermined band. There were drawbacks such as the need to omit some information.

The purpose of the present invention is to eliminate the above-mentioned conventional drawbacks, take advantage of the features of the TCI transmission method, and moreover, achieve efficiency by using a single circuit without expanding the frequency band or omitting part of the image information. It is an object of the present invention to provide a high-definition television transmission method suitable for application to satellite broadcasting, which can easily transmit high-definition color image signals.

That is, in the high-definition television transmission method of the present invention, a complete luminance signal is transmitted in every other scanning line period, and signal bands such as inter-scanning line differences and low frequency components are transmitted in the middle scanning line period. The narrowed luminance signal is compressed in time and transmitted, and one color signal or both color signals with narrowed signal bands are compressed in time and transmitted, and the remaining color signal information is
The time axis is compressed and transmitted during the horizontal blanking period of the scanning line period in which the complete luminance signal is transmitted, and the horizontal synchronization signal is transmitted only during the intermediate scanning line period. both sides of the signal,
In addition, by time-division multiplexing by omitting part of the information of the horizontal synchronization signal in a well-balanced manner, high-quality color image signals can be efficiently transmitted. Band-limited and time-axis compressed signal components are transmitted in alternate scanning line periods, and at least one of the color signals is transmitted during the horizontal blanking period of the scanning line period in which the signal components of the entire frequency band are transmitted. The signal components of a part of the frequency band are compressed in the time axis and transmitted, and the frequency band is restricted and the signal components in the time axis compressed are transmitted. This is characterized in that the signal components in the frequency band are compressed on the time axis and then transmitted.

In the following, the invention will be explained in detail with reference to a number of exemplary embodiments, with reference to the drawings.

First, the specifications of the high-definition color television signal referred to herein are as follows. It goes without saying that the transmission method of the present invention can also be applied to high-definition color television signals with different specifications.

Number of scanning lines 1125 (30 frames 2:1 interlaced) Scanning line period 29.6μsec Horizontal blanking period 6μsec Luminance (Y) signal band 20MHz Wideband color ( _CW ) signal band 7MHz Narrowband color ( _CN ) signal band 5MHz Next, FIG. 1 shows an example of the configuration of a color image signal encoding apparatus for forming a color image signal for transmission in the high-definition television transmission method of the present invention. The color image signal encoding device with the illustrated configuration includes:
A luminance signal Y and a line sequential color signal C are respectively supplied. Note that the signal band of each signal is as specified above. Therefore, the luminance signal Y is A-D
After encoding with a 48.6MHz clock signal in the converter 1-1, the 1-line memory 3-1,
3-2, an adder 4-1, and a coefficient unit 5-1, and an inter-line difference signal of the luminance signal Y is obtained at the output side of the subtracter 11-1 shown at point a in the figure. Note that various methods can be considered for forming the inter-line difference luminance signal a, but in the illustrated configuration example, for the luminance signal _Yo of the nth line, Yo _-
An operation of 1/2 (Y _o-1 +Y _o+1 ) is performed. This difference signal a is filtered to 10M by the low-pass filter 6-1.
After band-limiting to Hz, the nonlinear compressor 14 normalizes the signal amplitude and improves the signal-to-noise ratio of low amplitude components.
-1, sub-samples at 24.3 MHz, writes it into the 1-line memory 3-3 using a 24.3 MHz clock signal, reads it out using a 48.6 MHz clock signal, and compresses the time axis to 1/2.
A switch is used to select the time axis compressed luminance signal b.
In addition to SW ₁ , its changeover switch SW ₁
A complete luminance signal from the 1-line memory 3-1 is supplied to the other input terminal C of the 1-line memory 3-1 via a delay circuit 8-1 for synchronizing the timing, and the complete luminance signal C is time-base compressed. The luminance signal b is switched line alternately and guided to the changeover switch _SW3 .

On the other hand, the line sequential color signal c is processed by the A-D converter 2.
After encoding with a 24.3MHz clock signal,
The delay circuit 8-2 performs timing alignment with the luminance signal. Next, the narrowband color signal C _N is subsampled at 12.15MHz by the subsampler 7-2, and then written to the 1-line memory 3-5.
By reading at 48.6MHz, the time axis is compressed to 1/4 and the signal is guided to one contact f of the changeover switch _SW2 . Furthermore, the wideband color signal C _W is transmitted through the delay circuit 8-
After adjusting the timing with the narrowband color signal C _N using 3, 24.3M is stored in 1 line memory 3-4.
After writing with a Hz clock signal, it is read with a 48.3MHz clock signal, and after compressing the time axis to 1/2, it is led to the other contact e of the changeover switch _SW2 . The changeover switch SW ₂ , in conjunction with the changeover switch SW 1, outputs a wideband color signal C _W whose time axis has been compressed to 1/2 and a narrowband color signal C _N whose time axis has been compressed to _1/4 , for each line period. Switch alternately and supply to changeover switch SW ₃ . Therefore, switch SW ₁
When switch SW 2 is on the side of line-to-line differential luminance signal b, switch SW ₂ is on the side of broadband chrominance signal C _{W (e)} , and when switch SW ₁ is on the side of complete luminance signal c, switch SW ₂ is on the side of broadband chrominance signal C W (e). Narrowband color signal C _N (f)
On the side of Then, the changeover switch _SW3 switches between the luminance signal and the color signal within each line period, and time-division multiplexing is performed. Such a time division multiplexed signal is
Finally, the signal is sequentially passed through a DA converter 9-1 and a low-pass filter 10-1, and is extracted as an analog TCI color image signal.

Here, the signal waveform of the TCI color image signal obtained by the conventional TCI method is shown in FIG. In the conventional waveform shown in the figure, the color signals are line-sequential, the time axis of the wideband color signal C _W is compressed to 1/4, and the time axis of the narrowband color signal C _N is compressed to 1/5, respectively. It is inserted into horizontal blanking periods of alternate scanning line periods and time-division multiplexed with the luminance signal Y. In order to make the baseband band of the color image signal of the TCI method with such a configuration the same as the baseband band of 20MHz of the luminance signal Y, the band of the wideband color signal C _W is set to 5MHz, and the band of the narrowband color signal C _N is set to 4MHz. must, therefore,
It was considerably narrower than the standards for high-definition television signals. That is, although the sharpness of the luminance signal was sufficient, the sharpness of the color signal was insufficient.

In contrast, in the transmission method of the present invention, the luminance signal Y is subjected to appropriate processing to omit a portion of its transmission information, and the transmission information amount of the chrominance signal is increased by that amount, and the broadband chrominance signal C _W The signal band can be expanded to 10 MHz for the chrominance signal C _{N, and 5 MHz for the narrowband color signal C N} , and the signal processing applied to the luminance signal Y is limited to a level that can visually ignore image quality deterioration to improve color image quality. It is attached.

That is, the signal waveform of the time-division multiplexed color image signal of the transmission method of the present invention formed by the configuration shown in FIG. 1 is as shown in FIG.
Each component signal in the TCI color image signal has the following transmission signal band according to its respective time axis compression rate.

Wideband color signal C _W 10×2=20MHz Narrowband color signal C _N 5×4=20MHz Luminance signal Y 20MHz Line-to-line difference luminance signal 10×2=20MHz Therefore, both wideband and narrowband color signals C _W and C _N Although the transmission signal band is significantly increased compared to the conventional TCI method, the transmission signal band of luminance signal Y is only 20M.
Does not exceed Hz.

Next, FIG. 4 shows a configuration example of a decoding apparatus for a composite color image signal having the waveform shown in FIG. 3, which is formed by the configuration shown in FIG. 1. In the decoding device having the illustrated configuration, the received composite color image signal is encoded by the A-D converter 1-1 using a 48.6MHz clock signal, and then each gate circuit 12-
1 to 12-4, the luminance signal Y, line-to-line difference luminance signal, wideband chrominance signal _CW , and narrowband chrominance signal
Separate into _CN and take out. Furthermore, the narrowband color signal C _N
is written into the 1-line memory 3-5 using a 48.6 MHz clock signal, then read out using a 12.15 MHz clock signal, the time axis is expanded four times, and then guided to the interpolation filter 13-2 to be internalized. Perform interpolation to convert the data speed from 12.15MHz to 24.3MHz, and then supply it to one contact of switch _SW4 . Further, the wideband color signal C _W is written into the 1-line memory 3-4 using a 48.6 MHz clock signal, and then read out using a 24.3 MHz clock signal to double the time axis, and then to the delay circuit 8. -3, the signal is synchronized with the narrowband color signal C _N and then supplied to the other contact of the changeover switch _SW4 . The changeover switch SW ₄ alternately switches between the wide and narrow band color signals C _W and _CN to take out color signals line-by-line. The line sequential color signal is matched in delay amount with the system of the luminance signal Y in the delay circuit 8-6, and then converted into an analog signal by the 24.3MHz clock signal in the D-A converter 9-3. , taken out via a low-pass filter 10-3.

On the other hand, the differential luminance signal taken out from the gate circuit 12-2 is restored to an amplitude characteristic by a non-linear expander 15 using a characteristic opposite to that in the encoding device shown in FIG. to 48.6MHz
After writing using the 24.3 MHz clock signal, the time axis is doubled by reading using the 24.3 MHz clock signal. Further, the complete luminance signal Y transmitted on the lines before and after the line that transmitted the line-to-line difference luminance signal is taken out via two cascade-connected one-line memories 3-1 and 3-2, Adder 4
The -1 and 1/2 coefficient multiplier 5-1 restores the luminance signal Y of the line to which only the inter-line difference has been transmitted. In other words, since the actually transmitted line-to-line differential luminance signal is a band-limited differential signal of the form Y _o -1/2 (Y _o+1 + Y _o-1 ), 1/2 ( A signal in the form of Y _o+1 +Y _o-1 ) is taken out from the coefficient multiplier 5-1 described above, and after the timing is adjusted by the delay circuit 8-4, it is converted into a differential luminance signal by the adder 4-2. and restores a luminance signal Y close to the original luminance signal. The restored luminance signal is guided to one contact of the changeover switch SW ₅ , and the complete luminance signal is guided from the one-line memory 3-1 to the other contact, and the lines are switched alternately, and finally,
The signal is converted into an analog signal by a DA converter 9-2, and then taken out via a low-pass filter 10-2.

In this case, the line-to-line differential luminance signal is extracted in the form of Y _o −1/2 (Y _o+1 + Y _o-1 ), but the differential luminance signal may also be extracted in other formats. You can also set the basic clock frequency to 48.6M
Hz, 24.3MHz, but for example, 40MHz, 20MHz
Of course, other clock frequencies can also be used.

Using the encoding device shown in Figure 1 and the decoding device shown in Figure 4, a broadband color image signal in which each signal component is combined as shown in the signal waveform shown in Figure 3 is transmitted in a narrow band through a single channel and restored. To explain the advantages obtained by the color image signal transmission of the method of the present invention, first, regarding the luminance signal, the entire frequency band signal component of the luminance information is transmitted only every other line, and the middle of the entire frequency band transmission line is transmitted. When a line is transmitted by band-limiting the difference between the luminance information on the intermediate line and the average of the luminance information on both upper and lower adjacent lines, regarding the transmission of such inter-line difference luminance information on the intermediate line, By performing the following signal processing, the original broadband luminance signal can be almost restored.

In other words, for example, when transmitting a luminance information signal with a signal band of 20 MHz with the band limited to 10 MHz, the spatial frequency region that extends up to 20 MHz on each horizontal and vertical frequency axis is Divide into 4 areas A by 10MHz on each frequency axis,
Assuming that it is divided into B, C, and D, the spatial frequency regions of the luminance information signal whose band is limited to 10 MHz on the horizontal frequency axis by a low-pass filter are only the B region and C region shown in the figure. Therefore, for example, n
The signal components of band-limited regions B and C on the horizontal frequency axis in the th line are Y _oB and
When expressed as Y _oC , the line-to-line difference luminance information signal obtained by performing the difference calculation of Y _o -1/2 (Y _o-1 + Y _o+1 ) described above is Y _oB + Y _oC -1/2 {Y _o-1.B + Y _o-1.C ) + (Y _o+1.B + Y _o
+1.C )}(1).

Therefore, on the reproduction side that receives and decodes the line-to-line difference luminance information signal, when reproducing the band-limited line-to-line difference luminance information signal for every other line, as described above with reference to FIG.
In the line-to-line difference luminance information signal of equation (1), the high-frequency signal component on the horizontal frequency axis, which is deleted due to band limitation, is transmitted in four regions A, B, C, and D of the luminance signal on both front and rear adjacent lines. All frequency band signal components
Adding the average of Y _o-1 and Y _o+1 , Y _oB + Y _oC -1/2 {Y _o-1.B + Y _o-1.C ) + (Y _o+1.B + Y _o
+1.C )} +1/2 {Y _o-1.A +Y _o-1.B +Y _o-1.C +Y _o-1.D ) +(Y _o+1.A +Y _o+1.B +Y _o+1.C +Y _o+1.D )} =Y _oB +Y _oC +1/2{Y _o-1.A +Y _o+1.A )+(Y _o-1.D +
Y _o+1.D )}(2) By performing the calculation, the average of the high-frequency signals on the horizontal frequency axis in both the A and D regions is interpolated, and the band-limited differential luminance information is reproduced. The broadband original luminance signal can be restored to a state that substantially reproduces it.

In this way, for the luminance signal, complete information is transmitted every other line, and luminance information that is almost the same as the original signal can also be transmitted for the intermediate lines, so the quality deterioration of the luminance information signal is slight.

On the other hand, regarding the color signal, the wide and narrow band color signal C _W ,
Both C and _N can transmit color information signals in accordance with the standard.Furthermore, regarding wideband color signals, the standard signal band is 7MHz, but according to the above example, even if the signal band is expanded to 10MHz. There is now room for complete transmission. Furthermore, since the line-to-line difference luminance signal is subjected to non-linear compression and expansion, it is also advantageous in terms of improving the signal-to-noise ratio.
Furthermore, since it is a TCI method in which the luminance signal and the color signal are time-base compressed and time-division multiplexed, the spectral distribution approximates that of a monochrome image signal, making it suitable for FM transmission used in satellite broadcasting.

Furthermore, in the encoding device having the configuration shown in Figure 1, since the digital signal before D-A conversion is unified at a clock frequency of 48.6 MHz for both the luminance signal and the chrominance signal, the signal band is further compressed by digital processing. When applying this, the signal processing becomes easy. Furthermore, since the luminance signal transmits complete luminance information every other line, and there is no information loss in the color signal, the color image signal for transmission by the method of the present invention requires even greater signal band compression. There is plenty of room to do so. Furthermore, in the signal waveform shown in Figure 3, the zero level of the luminance signal and chrominance signal can be set respectively during the horizontal blanking period of the second line, so that the luminance level and chrominance signal level can be accurately reproduced. You also have the advantage of being able to do so.

Next, as another embodiment of the transmission method of the present invention,
Time-base compressed and time-division multiplexed color image signals are transmitted in the following manner. That is, regarding the luminance signal Y, for example, a low frequency component luminance signal Y _L of 0 to 10 MHz is transmitted for each line, and
The 20MHz high frequency component luminance signal _YH is transmitted every other line. On the other hand, the color signals are line sequential, the signal band of the wideband color signal C _W is 10MHz, and the signal band of the narrowband color signal C W is 10MHz.
The signal band of C _N is 5 MHz, the time axis of the wideband color signal C _W is compressed to 1/2, and the time axis of the narrow band color signal C _N is compressed to 1/4. Furthermore, the time axis of the low frequency component luminance signal Y _L is also compressed to 1/2. Therefore, the transmission signal band for each signal is 20MHz. Furthermore, the wideband color signal C _W is time-division-compressed with the low frequency component luminance signal Y _L and transmitted on the same line, and the narrowband color signal C _N transmits both the high and low frequency component luminance signals Y _L + Y _H. time-division multiplexing during the horizontal blanking period of the line to be processed. Note that, on the receiving/decoding side, for a line transmitting only the low-frequency component luminance signal Y _L , the high-frequency component of the luminance signal of the line is interpolated from the high-frequency component luminance signal Y _H of the lines before and after the line.

FIG. 6 shows an example of the configuration of an encoding device, ie, a color encoder, according to the transmission system of the present invention, which forms the TCI color image signal of the above-described aspect. In the encoding device with the configuration shown in the figure, the signal band is 20M.
Hz luminance signal Y, wideband color signal with signal band 10MHz
C _W and a narrowband color signal C _N with a signal band of 5 MHz are supplied, and the luminance signal Y is passed through an analog low-pass filter 17-
1, lead to A-D converter 1-1, 48.6M
After converting into a digital signal using a Hz clock signal, a digital low-pass filter 6-1 and a subtracter 11-2 are used to convert the low-frequency component luminance signal _YL up to 10MHz and the high-frequency component luminance signal Y from 10 to 20MHz. Separates into _H. Next, the high frequency component luminance signal Y _H is 1H
Delay lines 16-1 to 16-4, adders 4-4 to 4-
6 and coefficient multipliers 5-2 to 5-4 to perform vertical band limitation, and further thin out each line by a changeover switch _SW1 . Therefore, at point a on the output side of the adder 4-7, which adds the switching output of the switching switch SW ₁ and the low-frequency component luminance signal Y _L derived from the low-pass filter 6-1, , low-frequency component luminance signal Y _L and full-band luminance signal Y _L +
Y and _H appear repeatedly. The low-frequency component luminance signal Y _L and the full-band luminance signal Y _L +Y _H are distributed to different systems by switches SW ₁ and SW ₆ , which are switched synchronously, and the low-frequency component luminance signal Y _L is divided into different lines. After reducing the sampling frequency by half using the sub-sampler 7-1 and writing it to the 1-line memory 3-4 using a 24.3MHz clock signal,
The time axis is compressed to 1/2 by reading with a 48.6MHz clock signal, and for the full-band luminance signal Y _L + Y _H line, timing is only adjusted by writing to and reading from the 1-line memory 3-6. and take out the lines alternately from changeover switch SW ₆ . Therefore, output side b of changeover switch SW ₆
At the point, a low-frequency component luminance signal Y _L whose time axis is compressed to 1/2 and a full-band luminance signal Y _L +Y _H whose time axis does not change appear alternately and repeatedly on every other line.

On the other hand, two types of color signals, that is, wide and narrow band color signals C _W and C _N are passed through analog low-pass filters 17-2 and 17-3, respectively, to the A-D converter 1.
-2 and 1-3, the signal is converted into a digital signal using a 24.3MHz clock signal, and then converted into a line-sequential color signal by a line-sequential encoder ₁₈ . The time axis is compressed to 1/2 by writing using a clock signal and reading using a 48.6MHz clock signal.
Furthermore, the narrowband color signal C _N is transmitted to the sub-sampler 7-2.
The sampling frequency is halved and the time axis is compressed to 1/4 by writing with a 12.15MHz clock signal and reading with a 48.6MHz clock signal in the 1-line memory 3-5, and then The signals are alternately and repeatedly taken out every other line at point c on the output side of the changeover switch _SW2 .

The switching output b of the switching switch SW ₆ and the switching output c of the switching switch SW ₂ as described above are added together by the adder 4-8, including the synchronizing signal, and D-
A converter 9-1 and analog low-pass filter 17
-4, a time-division multiplexed composite color image signal having a signal waveform as shown in FIG. 7 is taken out.

Next, FIG. 8 shows a configuration example of a decoding device, ie, a color decoder, corresponding to the encoding device, ie, color encoder, shown in FIG. 6. In the decoding device having the illustrated configuration, the color image signal having the above-mentioned signal waveform is converted into a digital signal by the A-D converter 1-1 using a 48.6 MHz clock signal, and then the gate circuits 12-1 to 12-1 The signal is separated into a full-band luminance signal Y _L +Y _H , a low-band luminance signal Y _L , a wide-band chrominance signal _CW , and a narrow-band chrominance signal _CN . Next, 1-line memories 3-4 to 3-7, interpolation filters 13-2 and 13-3, and delay circuit 19-
1, 19-2, the time axis of each signal is
After expanding to 1, 2, 2 and 4 respectively,
Interpolation is performed for signals with low data speed, timing is adjusted for other signals, and the signals are separated into luminance signals and color signals.
via changeover switches SW ₄ and SW ₅ , respectively.
1-line delay line 16-1 to 16-6, adder 4-
14 to 4-18, a luminance signal vertical interpolation filter consisting of coefficient units 5-2 to 5-5, a low-pass filter 6-1 and a subtracter 11-3, one-line delay lines 16-7 to 16-12, and an adder. 4-9 to 4-13
The color signals are guided to vertical interpolation filters consisting of coefficient units 5-6 to 5-9, and the color signals are subjected to vertical interpolation to produce wideband color signals C _W and narrowband color signals C _N for all lines. restored over and over,
Regarding the luminance signal, for the line that transmitted only the low frequency component luminance signal Y _L , after performing interpolation of the high frequency component based on the high frequency component luminance signal Y _H transmitted to the lines before and after it, D -A converter 9-
2, 9-4, 9-5 and analog low-pass filters 17-4, 17-1, 17-2, luminance signal Y and wide and narrow band chrominance signal as analog signals.
Restore and extract C _W and C _N respectively.

In the decoding device shown in Fig. 8, if the luminance signal vertical interpolation filter circuit part shown surrounded by a broken line is omitted, the high frequency component luminance signal Y of the line before and after the line transmitting only the low frequency component luminance signal _YL is obtained. Since interpolation of high-frequency components based on _H is no longer performed, the horizontal signal band of the reproduced luminance signal is limited to 10 MHz for every other line, but the visual deterioration of image quality due to such signal band reduction is extremely slight. Therefore, by omitting this circuit portion, the structure of the decoding device, that is, the color decoder, can be simplified and made cheaper.

Next, the color image signal of the signal waveform according to the conventional TCI method shown in FIG. 2 and the composite color image signal of the signal waveform according to the transmission method of the present invention shown in FIG. 7 are switched and outputted in accordance with the content of the image. FIG. 9 shows a configuration example of an adaptive encoding device, that is, a color encoder. The encoding device having the configuration shown in Figure 9 is the configuration shown in Figure ₆ with the addition of a circuit section necessary for adaptive switching. Subtractor 11-4 that calculates the difference between the input and output signals of
At point d on the output side of , both horizontal and vertical high-frequency component signals of the luminance signal removed by the vertical low-pass filter circuit appear. In an image with normal content, the energy of this vertical high-frequency component signal is small, so there is no problem in removing it, but in a high-quality image, when the energy of this vertical high-frequency component signal is large, , the high image quality of the image is impaired, so in order to be able to transmit this vertical high-frequency component luminance signal as well, the subtracted output signal at point d is integrated and taken out by the square circuit 20 and the integration circuit 21, and the threshold value is The signal is supplied to the logic circuit 22 and compared with an appropriately set logic threshold, and when the threshold is exceeded, the changeover switches SW ₈ to _{SW 11} are controlled by the output signal of the threshold logic circuit 22, and the conventional
Change the configuration of the encoding device for the TCI method. In addition,
In response to this switching of configurations, a mode identification signal for identifying which configuration is used to form the color image signal is added to the composite color image signal and transmitted. Furthermore, since the signal band of the color signal differs due to such switching of the configuration, two systems of band limiting filters are prepared and switched.

FIG. 10 shows a configuration example of an adaptive decoding device, that is, a color decoder, corresponding to the adaptive encoding device configured as described above. In the configuration shown in the figure, after the received composite color image signal is converted into a digital signal by the A-D converter _1-1 , it is transferred to the decoding device 27 having the configuration shown in FIG. The decoding device 28 according to the method is switched and supplied, and the mode discriminating circuit 23
The above-mentioned mode identification signal is also determined, and the changeover switch is activated according to the result of the determination.
In addition to controlling SW ₁₂ , decoding devices 27 and 28
A selector switch that switches and outputs the output signal of
Also controls SW ₁₃ to SW ₁₅ . Note that the decoding device 27
and 28 have many circuit parts that can be shared, so it is preferable to simplify the configuration by switching only the different circuit parts.

Here, the effect of expanding the color signal transmission band obtained by the embodiment of the transmission method of the present invention described above with reference to FIGS. 6 to 10 has the following features. That is, the luminance signal Y in the composite color image signal transmitted by this embodiment is expressed in two-dimensional frequency as shown in FIG. A portion of the high-frequency component luminance signal Y _H represented by area C in the figure is transmitted every other line, and interpolation is performed on the intermediate lines during reception and decoding. Furthermore, since the high-frequency component luminance signal in area A in the figure that is not transmitted at all is a signal component representing a diagonal image component with a high frequency band, the image quality deterioration due to its deletion is visually minor. Therefore, by omitting some of the luminance signal components, the transmission band of the color signal is the same as that in regions D and E according to the conventional TCI method, which are shown shaded with diagonal lines in FIGS. 11b and 11c, respectively. As shown in regions E and G in the figure, both wide and narrow band color signals C _W and C _N can be expanded.

In addition, in the encoding device having the configuration shown in FIG. 8, interpolation of the luminance signal in the vertical direction is not performed with emphasis on the economical efficiency of the receiver, so that the encoding device shown in FIG.
Although the luminance signal component of area C is missing every other line, the visual deterioration in image quality due to the missing is slight. Furthermore, in the encoding device having the configuration shown in FIG. 9, when the energy of the luminance signal in area A in FIG.
Since the luminance signal of the area A is transmitted by switching to the TCI method, it is possible to transmit a color image signal with an image quality suitable for the image content. Therefore, according to the transmission method of the present invention, it is possible to efficiently transmit high-quality color image signals by compressing the transmission signal bands of the luminance signal and each color signal in a well-balanced manner, with almost no visual deterioration of the reproduced image quality. and traditional TCI
It is possible to perform high-definition color image transmission with superior image quality compared to the conventional method.

Next, FIG. 12 shows still another configuration example of the encoding device, that is, the color encoder in the high-definition television transmission method of the present invention. In the encoding device having the configuration shown in the figure, an analog luminance signal Y with a signal band of 20 MHz and analog wide-narrow band color signals C _W and _CN with signal bands of 10 MHz and 5 MHz, respectively, are line-sequentially converted by a line-sequential encoder (not shown). supply. Therefore, line-sequential wide-band and narrow-band color signals
After separating C _W and C _N by gate circuits 12-3 and 12-4, the broadband color signal C _W is guided to a low-pass filter 10-5 and a band filter 24-1 to It is separated into a gamut color signal C _WL and a high gamut color signal C _WH with a signal band of 5 to 10 MHz, and then the high gamut color signal C _WH is guided to a balanced modulator 26 to balance the carrier wave with an angular frequency ω _C = 2π × 10 MHz. modulate the balanced modulated output signal to the low-pass filter 1.
0-7 and extracting only the low sideband components, low frequency conversion high frequency color signals in the signal band 0 to 5 MHz are obtained.
Form C′ _WH .

The mode of signal band conversion in the above-mentioned signal processing process for the wideband color signal C _W in the line-sequential color signal supplied as an input signal is sequentially shown in FIGS. 13a, b, and c.

Low-frequency converted high-frequency color signal formed as described above
C' _WH , low range color signal C _WL and gate circuit 12-4
The narrowband color signal C _N extracted from the filter and passed through a low-pass filter 10-6 is supplied to A-D converters 1-4, 1-5 and 1-3, and converted into digital signals by a 12.15 MHz clock signal. And furthermore,
Supply to 1 line memory 3-10 to 3-12
After writing with 12.15MHz clock signal
It is read out using a 48.6MHz clock signal, and the time axis of each color signal is compressed to 1/4. In this way, the time-axis compressed low-frequency converted high-frequency color signal C' _WH is guided to the contact a of the changeover switch SW ₁ , and the time-axis compressed low-frequency color signal C _WL and narrowband color signal C _N are respectively guided. If the value added by the adder 4-19 is led to the contact point b of the changeover switch SW ₁ and the changeover switch SW ₁ is switched at the line period, the time-axis compressed low frequency conversion height is output at the output point c. The gamut color signal C' _WH , the time-base compressed low gamut color signal C _W , and the narrow band color signal C _N appear repeatedly in line periods, and the time-division multiplexed color signals are led to an adder 4-8.

On the other hand, the luminance signal Y supplied as an input signal is
The signal band is limited to 20MHz by the low-pass filter 10-4, and then led to the A-D converter 1-1 and converted into a digital signal by a 48.6MHz clock signal.
1 and the subtractor 11-3, the low-band luminance signal Y _L with a signal band of 0 to 10 MHz and the signal band
Separates into high frequency luminance signal _YH of 10~20MHz. Therefore, the high-frequency luminance signal Y _H is generated by the 1-line delay line 1
6-1 to 16-4, adders 4-4 to 4-6, and coefficient units 5-2 to 5-4 to limit the vertical signal band,
It is led to a changeover switch SW ₂ whose one contact is grounded, and is switched at line intervals, thinned out every other line, and then led to an adder 4-7, where the low When added to the band luminance signal Y _L , the full band luminance signal Y _L +Y _H and the low band luminance signal Y _L appear alternately and repeatedly every other line as the addition output. The line alternating addition output luminance signal is transferred to the changeover switch SW ₂ .
2 by changeover switch SW ₃ , which operates in synchronization with
The digital low-range luminance signal is separated into two systems, and the sub-sampler 7-1 is installed in the system with only the low-range luminance signal _YL to reduce the clock frequency of the digital low-range luminance signal to 1/2 to 24.3MHz.
Then, the time axis is compressed to 1/2 by writing it into the 1-line memory 3-4 and reading it out using a 48.6MHz clock signal. on the other hand,
A 1-line memory 3-6 that performs writing and reading at the same clock frequency of 48.6 MHz is provided in the system of the full-band luminance signal Y _L +Y _H , and only timing alignment with the low-band luminance signal Y _L is performed. Therefore, at the output side d of the changeover switch SW ₃ , the full-band luminance signal Y _L + without time axis compression is generated.
Y _H and a low-range luminance signal Y _L whose time axis is compressed to 1/2 appear repeatedly and alternately every other line. The line-alternating luminance signals are led to an adder 4-8,
By adding the above-mentioned time-division multiplexed color signal and synchronization signal and sequentially extracting the signal through the DA converter 9-1 and the low-pass filter 10-1, a time-division multiplexed color signal having the signal waveform shown in FIG. 14 is obtained. Multiple color image signals are obtained.

Next, FIG. 15 shows a configuration example of a decoding device, ie, a color decoder, corresponding to the encoding device, ie, color encoder, of the transmission method of the present invention having the configuration shown in FIG. 12. In the decoding device having the configuration shown in the figure, a composite color image signal having a signal waveform shown in FIG.
-D converter 1-1 and converted into a digital signal by a 48.6 MHz clock signal, and gate circuits 12-5 to 12-9 output the full-band luminance signal Y _L +Y _H and the low-band luminance signal Y _L , narrowband color signal C _N ,
Separate into low range color signal C _WL and low range converted high range color signal C' _WH , and store in 1 line memory 3-8, 3-7, 3-
5, 3-10 and 3-9, the time axis is expanded at the same ratio as in the encoding device shown in FIG. 12, respectively. Next, when the two types of luminance signals Y _L + Y _H and Y _L are led to the changeover switch SW ₄ and taken out alternately, a low-range luminance signal Y L with the time axis restored, a full-band luminance signal Y _L + Y H, and a full-band luminance signal Y _L + Y _H are obtained. are obtained by repeating the lines alternately. The line-alternating luminance signal is separated into a low-frequency luminance signal Y _L and a high-frequency luminance signal Y _H by a circuit section consisting of a digital low-pass filter 25-2 and a subtracter 11-4. _H to 1 line delay line 16-1
~16-6, adders 4-4 to 4-6 and 4-2
3 and a vertical interpolation filter consisting of coefficient units 5-1 to 5-4 to perform interpolation, and further,
At the adder 4-7, the digital low-pass filter 25
After adding with the low-range luminance signal Y _L from -2, D
- The analog luminance signal is restored by taking it out through the A converter 9-2 and the low-pass filter 10-2.

On the other hand, the low-pass converted high-band color signal C' _{WH , the low-band color signal C WL and} the narrowband color signal C are extracted by restoring the time axis in the 1-line memories 3-9, 3-10 and 3-5, respectively. For _N , DA converter 9-6
~9-8 and low-pass filters 10-8 to 10-1
0 restores the analog color signal. Further, the low frequency converted high frequency color signal C' _WH is guided to the balanced modulator 26 to perform balanced modulation on the carrier wave of the angular frequency ω _C , and the balanced modulated output signal is guided to the band filter 24-2 to transmit the upper sideband 5 to Restores the 10MHz high-frequency color signal. In addition,
As for this band filter 24-2, as with the low-pass filter 10-7 in the encoding device shown in FIG. It is assumed that the angular frequency ω _C of the carrier wave is the same as in the encoding device shown in FIG.

Then, by adding the high and low range color signals C _WH and C _WL restored as described above in an adder 4-20, the analog wideband color signal C _W can be restored.
Its analog broadband color signal C _W and low pass filter 1
If the adder 4-21 adds the analog narrowband color signal C _N extracted from 0-10 and timed by the delay circuit 8-10, the line-sequential color signal can be restored.

Next, the time-division multiplexed composite color image signal having the signal waveform shown in Figure 14 is divided into two channels and transmitted with the time axis of each channel expanded, thereby reducing the required bandwidth of the transmission line used. It can also be transmitted. FIG. 16 shows a configuration example of an encoding device, ie, a color encoder, in such a case, and FIG. 17 shows a configuration example of a decoding device, ie, a color encoder.

In the encoding device having the configuration shown in FIG. 16, the time-division multiplexed color image signal having the signal waveform shown in FIG. ₁₄ formed by the encoder 29 having the configuration shown in FIG. Line memory 3-11 and 3-1
After writing with a 48.6MHz clock signal and reading with a 24.3MHz clock signal, the time axis is doubled and the signal band is halved to 1/2, and then the D-A converter 9-2, 9-3 and low-pass filters 10-11, 10-12, respectively, to form a two-channel transmission path with a transmission band narrower to 1/2 compared to the configuration shown in FIG. Send. In the illustrated configuration example, the 1-line memories 3-11 and 3-12 are provided to double the time axis of the color image signal, but in reality, the 1-line memory in the encoder 29 It is preferable to simultaneously perform signal processing corresponding to such time axis expansion using the following.

The above-mentioned two-channel transmission paths are called A channel and B channel, and the A channel converts the low frequency converted high frequency color signal _C'WH and the full band luminance signal _YL.
When transmitting a time division multiplexed signal with + _YH , depending on the B channel, a low band color signal C _WL
A time-division multiplexed signal of C _N and low-band luminance signal Y _L will be transmitted.

On the other hand, in the restoration device having the configuration shown in FIG. 1-line memory 3-13,
3 to 14 respectively, and after writing with a 24.3MHz clock signal, read out with a 48.6MHz clock signal to compress the time axis to 1/2, respectively.
The signal is supplied to a decoder 30 having the configuration shown in FIG. 15 to restore an analog luminance signal and an analog line sequential color signal.

Note that by receiving and decoding only the time-division multiplexed signal of the B channel, it is possible to restore the low-band luminance signal _YL and the wide-band and narrow-band chrominance signals, although only the low-band components. can be used to reproduce an ordinary standard color television signal.

According to the embodiment of the transmission method of the present invention described above with reference to FIGS. 12 to 17, the conventional TCI
The signal band of each color signal can be significantly expanded compared to that of the system composite color image signal, and the reproduced color image quality can be significantly improved. Furthermore, if the time-division multiplexed color image signal is divided into two channels and the time axis of each channel is expanded, a high-definition color television signal can be transmitted with high image quality even through a normal transmission path with a relatively narrow transmission band. Color images can be reproduced.

Therefore, according to the transmission method of the present invention, the conventional
It is possible to transmit high-definition color television signals with much better image quality than the TCI method, and if two-channel transmission is adopted, two types of services can be provided at the same time.For example, only one channel can be received. It is now possible to simultaneously provide a service for converting images into standard format color image signals and a service for receiving high quality color image signals using two channels, allowing both high definition television and standard format television to be compatible, which was previously considered difficult. You can get sex.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of the configuration of an encoding device in the high-definition television transmission method of the present invention;
FIG. 2 is a waveform diagram showing a signal waveform of a time division multiplexed transmission signal according to a conventional transmission method, FIG. FIG. 4 is a block diagram showing an example of the configuration of a decoding device corresponding to the encoding device having the configuration shown in FIG. 1 in the transmission method of the present invention, and FIG. FIG. 6 is a block diagram showing another configuration example of the encoding device in the transmission method of the present invention, and FIG. 7 is a signal waveform of the time division multiplexed transmission signal by the encoding device shown in FIG. 6. FIG. 8 is a block diagram showing an example of the configuration of a decoding device corresponding to the encoding device with the configuration shown in FIG. 6 in the transmission method of the present invention, and FIG. FIG. 10 is a block diagram showing a further example of the configuration of the apparatus; FIG. 10 is a block diagram showing an example of the configuration of a decoding device corresponding to the encoding device having the configuration shown in FIG. 9 in the transmission method of the present invention; FIGS. b and c are characteristic curve diagrams respectively showing the mode of two-dimensional frequency distribution of each component signal in a time division multiplexed transmission signal by the encoding device shown in FIG. 6, and FIG. 12 is a further diagram of the encoding device in the transmission method of the present invention. Block diagram showing an example of the configuration of
Figures 3a, b, and c are characteristic curve diagrams sequentially showing the manner of converting the broadband color signal band in the encoding device shown in Figure 12, and Figure 14 is a time division multiplex transmission signal by the encoding device shown in Figure 12. 15 is a block diagram showing an example of the configuration of a decoding device corresponding to the encoding device having the configuration shown in FIG. 12 in the transmission method of the present invention, and FIG. 16 is a waveform diagram showing an example of the signal waveform of the present invention. FIG. 17 is a block diagram showing yet another example of the configuration of the encoding device in the transmission method of the present invention, and FIG. 17 is a block diagram showing an example of the configuration of the decoding device corresponding to the encoding device having the configuration shown in FIG. 1, 2...A-D converter, 3...1 line memory, 4...Adder, 5...Coefficient unit, 6, 10...
Low-pass filter, 7... Subsampler, 8, 19...
...Delay circuit, 9...D-A converter, 11...Subtractor, 12...Gate circuit, 13...Interpolation filter, 14...Nonlinear compressor, 15...Nonlinear expander, 16... ...1-line delay line, 17... Analog low-pass filter, 18... Line sequential encoder, 20
... Square circuit, 21 ... Integration circuit, 22 ... Threshold logic circuit, 23 ... Mode discrimination circuit, 24 ... Band filter, 25 ... Digital low-pass filter,
26...Balanced modulator, 27...Decoder shown in FIG. 8, 28...Conventional TCI method decoder, 29...
. . . Decoder shown in FIG. 12, 30 . . . Decoder shown in FIG. 15.

Claims (1)

[Claims] 1. A method of transmitting signal components in all frequency bands in a luminance signal and signal components whose frequency bands are limited and compressed in time axis in alternate scanning line periods, and transmitting signal components in all frequency bands in a luminance signal. A signal component in at least a part of the frequency band of one color signal is compressed in time axis during the horizontal blanking period of the scanning line period to be transmitted, and the signal component is compressed in time axis while limiting the frequency band. 1. A high-definition television transmission method characterized in that signal components of all frequency bands in at least the other color signal are time-base compressed and transmitted during the remaining period of the scanning line period in which the color signal is transmitted. 2. A high-definition television transmission method according to claim 1, characterized in that the frequency band is limited and the time-domain compression ratio of the time-domain compressed signal component is reduced to 1/2. . 3. A high-definition television transmission method according to claim 2, characterized in that the time axis compression ratio of the other color signal is set to 1/2. 4. In the transmission method according to claim 1 or 2, the frequency band is limited and the time axis compressed signal component is used as a difference between the luminance signals between adjacent scanning line periods,
A high-definition television transmission method, characterized in that the one color signal is a narrowband color signal, and the other color signal is a wideband color signal. 5. In the transmission method according to claim 1 or 2, the frequency band is limited and the time axis compressed signal component is used as a low frequency signal component in the luminance signal, and
A high-definition television transmission method, characterized in that among signal components of all frequency bands in the luminance signal, signal components of high frequencies are vertically band-limited. 6. A high-definition television transmission method according to claim 5, characterized in that the one color signal is a narrowband color signal, and the other color signal is a wideband color signal. . 7. In the transmission method according to claim 5, a signal obtained by converting the signal components of at least a part of the frequency band in the one color signal to the frequency band of the high frequency signal component in the broadband color signal to a low frequency band. component, and the other color signal as a narrowband color signal whose time axis is compressed to 1/4,
A high-definition television transmission method characterized by transmitting a wideband color signal with a time axis compressed to 1/4 along with a low frequency signal component.