CA1325055C

CA1325055C - Dual channel video signal transmission system

Info

Publication number: CA1325055C
Application number: CA000611169A
Authority: CA
Inventors: Heinz-Werner Keesen; Hartmut Peters; Dietmar Hepper
Original assignee: Deutsche Thomson Brandt GmbH
Current assignee: Deutsche Thomson Brandt GmbH
Priority date: 1988-09-13
Filing date: 1989-09-13
Publication date: 1993-12-07
Anticipated expiration: 2010-12-07
Also published as: EP0359094B1; SG66493G; SG36672G; CN1027483C; KR900702718A; AU4191389A; ATE83595T1; HK78594A; EP0359094A1; US5055927A; WO1990003082A1; DE58903019D1; EP0439471A1; CN1041254A; ES2037358T3

Abstract

Abstract Video signal information derived from a high definition source is conveyed via two channels. A first channel conveys relatively low spatial resolution, high temporal resolution video information compatible with a standard television receiver. An auxiliary second channel conveys relatively high spatial resolu-tion, low temporal resolution video information. A high defini-tion television receiver reconstructs original high definition information from the first and second channel information.

Description

The invention concerns a two channel television signal transmission system for transmitting video information derived .: .
from a high definition video source.
In the proceedings of the meetings of a 1987 HDTV
colloquium, from Oct. 4 through 8, 1987, a transmitting system has -~been suggested in the article "High definition televised compatible transmission system", W.E. Glenn et al., December 1987, IEEE Transactions on Broadcasting, Vol. BC-33, No. 4, New York.
The suggested system allows the recept1on of a high definition television (HDTV) signal as well as the recepti~on of a standard television (TV) signal. In such system~an~HDTV slgnal is separated by means of a digital signal~proc~essor~a~nd a two- ;
dimensional spatial filter to produce a standa~rd TV signal and a signal which contains high spatial frequency port~ions of~the HDTV
signal.
Both signals are transmitted~v~ia~two separate ~band restricted channels. One channel transmits~the standard TV
signal, and an auxiliary second channel~transmits high spatial frequency portions of the HDTV~sig~nal~. The~standard TV signal~can ~-be received by a standard TV recelver~ ;By~eva~Iuating the~signal content of both channels, a suitable~HDTV receiyer can reconstruct and reproduce the high definition~;picture~from thq original source. A high resolution picture ~cannot~be reconstructed and reproduced solely from the information~contained in the auxiliary second channel.
.~,.. ,;
The present invention Goncérns a~ system~which allows the ;-reconstruction of picture informatlon~in the~case~of existing : ~ ~ .. ,, :.

bandwidth restricted transmitting channels on the receiver side, even if only one channel can be received.
At the transmitter an HDTV signal with high temporal and spatial resolution is split into two signals. The first signal is characterized by low spatial resolution but high temporal resolution. sy using an appropriate code, such signal can be -~
~ransformed into a standard TV signal, e.g. PAL, Secam, NTSC or D2-MAC, or it may be : , ,; .
- , ., ~:; ': ' ' :, -la~

1 325~

transmltted dlgitally wlth or without data reductlon vla a flrst bandwidth restrlcted channel.
The second slgnal ls characterlzed by hlgh spatlal resolutlon and a low temporal resolutlon. Thls can be achleved, for example, by ellmlnatlng lmage lnformatlon, e.g.~ vla a sub-sampllng process whlch removes every second lmage frame. By means ;;~
of an approprlate encoder the slgnal can be transformed lnto an HD-MAC slgnal, or it can be transmitted digitally wlth or wlthout data reductlon, through a second bandwldth restrlcted channel. On ~ ~
the recelver slde, a complete low spatlal resolutlon, hlgh tempor-al resolutlon lmage slgnal can be recelved via the flrst channel.
- ,' ' ., In contrast to the state of the art, a complete low ~, temporal resolutlon, and hlgh spatial resolutlon vldeo slgnal can be recelved vla the second channel, and~a sultab1e (spatlally) high deflnltlon lmage slgnal can be reconstructed uslng appro- ;
prlate decodlng and lmage regeneratlon processes. These processes reconstruct lnformatlon whlch ls lo~t at the recelver vla the ~;
imaye removal process practlced at the receiver, partlcularly ln the case of motlon sequences, as ~ar as posslble.
In order to regenerate a complete HDTV s1gnal, both channels have to be evaluated at the recelver. For thls purpose, partlcularly ln the case of lmage motlon, the hlgh temporal resolutlon lmage lnformation of the f1rst channel i8 used for reconstructing the hlgh deflnltlon image. -The slgnal of the second channel~ls supplemented wlth ~nformation from the flrst channél. Whlle recelvlng the second channel thls informatlon can be evaluated by the receiver to the -...... ..

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1 325055 :;

effect that the receiver automatlcally allows the receptlon of the flrst channel by means of an approprlate evaluatlon clrcult.
The dlsclosed transmlsslon system accordlng to the ln-ventlon advantageously ls a hlgh deflnltlon system whlch ls com~
patlble wlth the standard TV transmlsslon system. In the dls~
. . .
closed system the flrst channel provldes a plcture slgnal wlth a ;
resolutlon ln accordance wlth the exlstlng conventlonal televlslon ; standards of today, and the second channel provldes a plcture - ~ , .. -- .
slgnal wlth hlgher spatial resolutlon. : -In the drawlng, - FIGURE 1 shows a two channei televlslon sfgnal trans-- mlsslon system accordlng to the present lnventlon;
FIGURES 2-6 and 8 show detal~ls~of portlon8 of the system of FI~URE l; and ; FIGURE 7 shows a slgnal d~lagr helpful~ln understandlng the operatlon of the system.
In FIGUR~ 1 a hlgh definitlon toleVl310n~slgnal HDTV
from a source such as a televlsion camera ls fed tola flrst trans- ' ~ . , .
mlsslon path comprlslng a transcoder l, a~TV~slgnal~encoder 2, a ~ ~ `
TV signal decoder 3 and a transcodqr 4.~A~second transmlsslon path comprlses an lmage suppresslon;~C;lrcult 5~an~H~ encoder 6, an HD decoder 7 and an lmage regeneratlon~clrcult 8. -Transcoder 1 of the flr~st~transmlssion~pat~h, vla appro- - -~
prlate fllterlng networks, reduces~horizontal lmage resolutlon by a rate of 2:1, and reduces vertlCal~ lmage~resolUtlon by a rate of 3:2. In addltlon input slgnal HDTV,~ whlch~ls;~non-lnterIaced, ls ~-~
transformed lnto an interlaced slgnal whereby temporal resolution ~:

~ . :

: -, 1 325~5 27779-5 :
is preserved. The output slgnal of transcoder 1 ls fed to TV ~-encoder 2 whlch produces a standard TV slgnal, e.g. in PAL, Secam, NTSC or D2-MAC format, and the output of whlch ls connected to an output of the flrst transmlsslon channel for broadcast vla an approprlate medlum. Alternatlvely, lf the output of the trans- ` ;
coder ls to be stored, e.g., via a dlgital recorder, it is trans-ferred either dlrectly or vla a data reductlon network to a re-cordlng channel. -In the receiver portlon of the flrst transmlsslon chan~
.: :: .::
nel the lncomlng standard TV slgnal ls decoded ln a TV decoder 3.
A standard TV signal ls produced at the output of decoder 3.
In the second channel the HDTV slgnal 18 sub~ected to a process of suppresslng or ellmlnatlng lmage informatlon for the :
purpose of adapting the HDTV slgnal to the bandwldth-restricted ;
second transmisslon channel. Picture suppresslon clrcuit 5 per-mlts, e.g., only every other plcture frame to be transmltted such as by means of a 2 5 1 subsampllng proCeSs. The suppresslon of more than ~ust every other lmage frame ls posslble ln the presence of A ,~ ' ' motlonless lmage lnformation, so that the channel capaclty whlch ...... .
becomes avallable can be used for the codlng and transmlsslon of the other lmage lnformatlon. The output slgnal ~rom plcture sup- .. .-pression clrcult 5 ls coupled to an HD (hlgh deflnltlon) encoder 6. HD encoder 6 elther produces an analog slgnal, for example an HD-MAC signal, or a dlgltal slgnal, whlch ls transmltted elther dlrectly or after data reductlon.
In the receiver for the second trangmlsslon channel, the lncomlng slgnal ls applled to an HD decoder 7. The~output of HD

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1 32~05~ ;
27779-5 `
decoder 7 ls connected to a plcture regeneratlng clrcult 8, whlch reconstructs lmages removed at the transmltter vla a motlon estl-matlon technlque lnvolvlng comparlson of blocks of lmage plxels.
At the output of circuit 8 an HD signal wlth hlgh spatial resolu-tlon and with a scanning rate of e.g. 50 Hz ls provlded, but wlth possible errors in the case of image motlon.
In order to reduce these errors ln areas of lmage motlon to thereby lncrease temporal resolutlon of the lnco~lng HDTV
slgnal, from the standard TV slgnal a transcoder 4 performs an ~-lnversion of the scanning rate converslon prevlously performed by transcoder 1. Output slgnals from transcoder 4 and from picture regeneration clrcult 8 are applled to a slgnal comblnlng and ~ -flltering network 9, whlch by means of approprlàte slgnal welght~
lng dellvers an HDTV output slgnal w1th hlgh temporal and spatlal resolutlon.
FIGURE 2 shows addltlonal detall8 of transcoder l ln the transmltter of FIGURE 1. Input slgnal HDTV~1s appIled to a horl- -zontal transcoder fllter 9, Whlch lowers the horizontal 8cannlng rate by 2:1 by means of appropriate 11terlng. A~sUltable proce~
dure for this purpose ls descrlbed by Plrsch, et al. in "Changlng the Sampling Rate of Vldeo Slgnals by Ratlonal~Factors", publlshed -~
.~ ~ - , .
ln Proc. EUSIPCO '83, Signal Process1ng II:~ Theorles and Appllca- ~;
tions, EURASIP 1983, pp. 171-174. The s1gna1~f~rom unlt 9 18 further processed by vertlcal transcoder fllter 10, whlch lowers the vertical scannlng rate by 3.2. ~Subsequently, the slgnal ls :
vertlcally low pass flltered and afterwards~ proces~sed by an lnter-lacer 11, whlch carrles out a frame-dependent vertlcal sub--:

1 3250~5 ~ .
27779-5 ~'' sampllng of 2:1 to produce a llne lnterlaced vldeo slgnal.
If the HDTV slgnal at the lnput of transcoder 1 con- ~;
talns, for example, 1440 x 864 actlve plcture elements (plxels) '' per lmage wlth an lmage repetltlon frequency of 50 Hz and pro- ' ' gresslve scannlng of 1:1, the lmage plxel format ls reduced ln the followlng steps: 720 x 864 plxels at 50 Hz, l:l; then 720 x 576, '' ' 50 Hz, 1:1; then 720 x 5~6, S0 Hz, 2~1 lnterlaced. ~ ' FIGURE 3 shows addltlonal detall8 of transcoder 4 ln the '~
recelver of FIGURE 1. The lnput standard televlslon slgnal TV, .~''' present ln the form of dlgltal scannlng values, ;18 applled to a de-lnterlacer 12 whlch, by frame-dependent llne~prooesslng and lnterpolatlon of lntermedlate llne~, generates a video slgnal wlth the format 720 x 576 plxels, 50 Hz, l,I non-lnterlaced from a ' '~' vldeo slgnal wlth the format 720 x 576 plxels~,~ 50 Nz, 2:1 lnter-laced. Thls slgnal ls applled to a vertlcal transaoder fllter 13, whlch regenerates a slgnal ln the format 720 x 864 plxela, 50 Hz, 1:1 by means of vertlcal scannlng rat'e~'conver810n. ~y means of a subsequent horlzontal transcoder fllter 14 ulth a horlzontal scan~
nlng rate converslon factor of 1s2~ a~vldeo slgnal~wlth 1440 x 864 plxels, 50 Hz, 1 sl lS generated wlth~a format'slmllar to that of '~'' -~ ! . .
the HDTV lnput slgnal.
FIGURE 4 shows detalls of HD~encoder 6~of~FIGURE 1. The '. ' HDTV slgnal from the output lmage suppresslon-ci~rouit 5 ls applied ';`
to a mode selectlon clrcult 23 and to an~lmage block search clr- ~ -cult 31.
In the mode selectlon clrcult:~23,~by comparlng the lnput -signal wlth an output slgnal fros block ~search~c1rcult 31, elther ~ ' '' ", f. ' ~ ~ 6 ~

1 32~055 an lnterframe or an lntraframe mode is chosen for codlng the lnput signal. The coding ls performed, for example, conslstently for an lmage block whlch contalns 8 x 8 plxels. If the devlatlons be~
tween the actual and the precedlng plcture are too large, lntra-frame codlng is used. In the other cases interframe codlng ls used to obtaln data reductlon. In the lnterframe mode the plcture slgnal ls predlcted along the prevlously determlned motlon vec-tors, and the dlfference slgnal between the orlglnal and the pre~
dlcted slgnal is transmitted. In the lntraframe mode the input slgnal ltself 18 advanced. The image block search circuit 31 establlshes a motlon vector for each actual l~age block. The motlon vector can be determlned e.g. from the;;mlnlm~m sum of the absolute values of the dlfferences, from;the~mlnlmum sum of the~
alternating energy or from the mlnlmum varlance.
From mode selectlon clrcult 23~the~slgnal 18 applled to ``
a dlscrete coslne transformer 24. Its output~slgnal 18 scanned by ;--a sorter ~scanner) 25j and is sUbseqUently;CoUpled to a slgnal welghtlng clrcult 26 and to a quantl8er 2~7. The~;~output slgnal of quantlzer 27 ls coupled to an encoder 28 and to~an lnverse welght~
lng network 36 for reconstructlon of the lmage~slgnal, followed by an lnverse scanner 35 and an Inverse~dlscrete~coslne transformer 34 of a block reconstructlon clrcult~33j~ the~output~ of which 18 ~;
connected to a plcture memory 32.
Encoder 28 recelves quantlzed~welghted transformatlon coefflcients as lnput signals ln a sequence whlch is determlned by : ; . . .
the scannlng. For the purpose of data~reduction lt uses varlable word length codlng and provldes coefflclents and addresses whlch ~ ~ , .-7 ~ ~

~ .

1 3250~5 are encoded as an output slgnal. Thls output slgnal ls applled to a vldeo-multlplexer and buffer storage unlt 29 from whlch an OUTPUT slgnal ls provlded. ~ ~ -The data stored in picture memory 32 are data pertainlng .-~-..; :., .
to the precedlng lmage. Such data are needed to determlne motion :;
lnformatlon for an actual lmage block. For thls purpose an lmage ^
block comprlslng 8 x 8 plxels of the actual plcture (wlthln a search area of the precedlng plcture comprlslng e.g. 16 x 16 plxels) ls shlfted ln posltlon withln the 16 x 16 block by means lQ of the so-called block matchlng method untll a posltlon of the actual lmage block has been found in the preceding lmage block where the lowest number of dlvergences are detect~ed. A vector ls .-`
determined from thls newly establ1shed poslt10n,~and ls coupled to mode selectlon clrcult 23 and to an encoder~30.~Encoder 30 also ~:
employs varlable word length and transmlts the~coded motlon vector -~
to vldeomultlplexer and buffer storage 29 for lnter~edlate storlng together wlth the correspondlng slgnal~data. For~the purpose of controlllng the quantlzatlon operatlon;,;;an output~of buffer -storage 29 ls connected to a controI lnput~of~quantlzer 27.; The .`~
result of the mode selectlon from unlt 23 ls applled to vldeo-multiplexer and buffer storage unlt 29 and,~for the correct~bloc~ ~ -reconstructlon, to block reconstructlon~clrcuit 33.l The output slgnal from buffer storaqe unlt 29;1s~app11ed to~the second trans- ;
mission channel at a constant data rate.
FIGURE 5 shows addltlona~1 detal~1s of HD decoder 7 of FIGURE l, wlth an lnput buffer storage and vldeomultlplexer 15.
Separate outputs of buffer storage unlt~l5~}ead to decoders 16 or : : ~ .. '' .

1 325~5~ ~
27779-5 ;
21 respectlvely. An output of decoder 16 leads through an lnverse welghtlng unlt 17, an lnverse scanner unlt 18, and an lnverse dls- ;
crete coslne transformer 19 to a block reconstructlon clrcult 20.
The output of block reconstructlon clrcult 20 leads to lmage re- ;
generatlon clrcult 8 of FIGURE 1 as well as to an l~age block memory 22. The output of decoder 21 wlth decoded motlon vector ;
lnformatlon ls applled to a further lnput of lmage block memory 22 vla a path 53. In decoder 16 the addres8es and coefflclents are decoded lnto thelr orlglnal form. Decoder 21 performs the same '~
functlon wlth respect to the motlon vect~ors.
An lnformatlon llne 54 leads from bufer ltorage unlt 15 '~^
to lmage block reconstructlon clrcult 20 w1th lnformatlon as to whether the lmage block was encoded ln~an~lnt~erframe or lntraframe mode. A further lnformation llne 56 leads~from~buffer storage unlt 15 to decoder 16, and transmlts 1n~ormatlon~as to the state of the buffer ~torage and the quantlzlng~status.~
FIGURE 6 showq additlonal detall5 of~picture regenera- ;
tlon clrcult 8 of FIGURE 1. The output~signa1~from~HD decoder~7 of FIGURE 1 18 applled to a plcture memory~38.~ One output of ~
memory 38 leads to a plcture lnte~rpolatlon clrcult~37, and another output leads to a plcture memory 39 and to~a~mult1p1exer 40.
Flrst and second lnputs of plcture lnterpolatlon clrcult --37 provlde addltlonal data from HD décoder 7~,~1.e., motlon vectors 53 and the encoder mode lnformation~54~1;.e. lnformation as to lnterframe or intraframe codlng).- An-output~of lnt~erpolatlon clr- ~-cuit 37 leads to multlplexer 40. The~out~put~of multlplexer 40 provid~s an HD slgnal wlth 1440 x~86~p1xe1~ correspondlng to a g~
, -27779-5 ; ^
.:.. ::-.-5 x 3 lmage aspect ratlo herelnafter referred to as the HDTV-TV ' ~' s lgnal . ', ,.'.
The operatlon of plcture generator 8 shown ln FIGURE 6 '~' ls lllustrated in FIGURE 7 by means of a one-dlmenslonal example.
Each 2n+1 plcture output from the HD decoder ls stored ln plcture memory 38 of the plcture regenerator. The prevlously '~
transmltted 2n-1 plcture ls malntalned ln plcture memory 39. The ' lntermedlate plcture, 2n, was ellmlnated at the transmltter by ~.' plcture suppresslon clrcult 5.
FIGURE 7 shows slgnals assoClated wlth plcture lnter~
polation circult 37. A first input reCelVes~oUtpUt~slgnal 46 from '~'`' ~-plcture memory 39 containlng lmage lnformatlon~;49;and 50. The second lnput recelves output slgnal 48~from plct~ure~memory 38. ~ , Output slgnal 47 contalnlng plcture informatlon~51-~is applled to ' ' multiplexer 40.
If lmage block 52 of the presently~prooessed plcture was '.' transmltted ln lntraframe mode vla the cha~nnel, then block 51 of lntermedlate plcture 2n 18 dlrectly determlned from;,the 2n-1 ;" -plcture and the 2n+1 plcture on a block~basls~by~means of a plxel averaglng process (not'shown ln FIGURE~7). In~the case o an ;': ' . . ,- . .
lntraframe codlng, however, motlon vector~53~assoclated wlth lmage , block 52 ls known from the HD decoder.~'For lmage~block 51, whlch ~` ' ls to be lnterpolated, lmage block 50~of~the~2n-l~ plcture (46) "''''~' which is shlfted by half the amount~of~motlon~vect~or 54, ls adop- ' ' te~. Furthermore, the 2n plcture can be~generated by plxel lnter- ' ' ~. .. - .
polatlon of the 2n-1 and 2n+1 plcture elements whlch have been shlfted ln opposlte directlono by half~;~the~amount of the motlon - '-: '..

:

1 325055 , .~

vector.
FIGURE 8 shows detalls of spatial-temporal fllter and comblner 9 ln FIGURE 1. The hlgh temporal resolutlon, spatlally lnterpolated TV slgnal - thus, as regards format, correspondlng to the ~DTV plcture - whlch ls generated by transformer 4 ln FIGURE 1 .' ls applled to one lnput of a summlng unlt 41. The HD output slg-nal from plcture regeneratlon clrcult 8 of FIGURE 1 ls applled to ~. -. ': . -' another lnput of summlng unlt 41. Summer 41 determlnes the sum of the absolute grey-scale dlfferences of the two dlfferently regen-erated lnput image slgnals on a plxel-by-plxel ba~ls vla an n x n ~
"wlndow". The sum results ln an output slgnal of~value Z wlth a :~:
wlndow dlmenslon of n x n. ~
.. .
Output slgnal Z from summer 41 1s rece~lved by A clrcult : ;-:
43, whlch determines factor~ for the welghtlng of the TV and HD ::
vldeo slgnals. Thus, ln a multlpller 42 the~TV~slgnal ls multl-plled by a factor "a", whereas the HD slgnal ls multlplled by a factor "l-a" ln a multlpller 44. Dependent upon the value of ;
slgnal Z, welghtlng factor "a" may take a value between 0 and 1. ~ :
`
If the value of slgnal Z ls large, (l.e. if due to :~
, .
slgnlflcant lmage motlon erroneous lnterpolatlon results are present in plcture generator 8 of FIGURE 6~) then factor a = 1 and the plcture lnformatlon of the TV slgnal ls~adopted. If, on the : ~-contrary, the value Z ls very small l1.e.~lf the vldeo slgnal exhibits llttle or no lmage motlon) then the data are taken from the HD slgnal, whlch contalns the orlglnal hlgh spatlal resolutlon informatlon. Output slgnals from multlp11ers 42 and 44 are added - --ln a summlng unit 45, the output slgnal of whlch corresponds to - ~

: . ~ ' ' ,, 11 ~
'~
~.. -.

27779-5 ; ~
the inltlal HDTV slgnal. -The HD lmages transmltted vla the second transmlsslon channel are dlrectly fed to the output of comblnation fllter 9 ln FIGURE l; correspondlngly, factor "a" exhlblts a value of zero for the entlre lmage.
The lmage generatlon procedure ls carrled out by evalu-atlng both channels at the recelver. For thls purpose the lmages generated by the above-mentloned plcture regeneratlng proCedUres are comblned as follows. The dlfferences between~the hlgh tlme : ., ~ ,.
resolutlon, spatlally lnterpolated HDTV-TV slgnal ~produced by -transcoding) whlch corresponds to the HDTV as regards format, and the HDTV-HD plcture generated by plcture lnterpolatlon, are calcu-.. .. ..
lated plxel by plxel. Via an n x~n wlndow the sums of the abso~
lute grey-scale dlfferences of the two dlfferently regenerated picture slgnals are determlned and welghted on a~plxel-by-plxel ,. ~ ..
basls. ~y thls process a welghtlng factor "a" ls~determlned ln ~:
the range between 0 and 1. The HDTV-TV and HDTV-HD~video slgnals are comblned wlth welghtlng factor a a8 folloWs~ The HDTV-TV
. . - . . .
slgnal ls multlplled by factor a, while the HDTV-HD slgnal is ~, , .
multlplled by factor l-a. ~ ~
If erroneous lnterpolatlon resultS have occurred durlng ~ -the regeneration of the HDTV-HD vldeo slgnal~due to~slgnlflcant image motion, then factor a = 1 and the~plcture~lnformatlon of the ;`-HDTV-TV slgnal ls adopted. If, on the contrary, the value of ~ ~
. . .:
factor "a" ls very small, l.e., the lmage lnformatlon ls essen-.. . ...
tially statlc, then the vldeo lnformatlon ls taken from the HDTV- ~

HD signal, as thls represents the orlglnal hlgh spatlal resolu- - -~., .

tion. The welghtlng factor "a" ls set to 1 lf the Welghted sum of --the absolute grey-scale values exceeds a threshold value whlch ls smaller than 1. Up to thls threshold value the value of the welghtlng factor lncreases proportlonally from O to 1.
In addltlon, the welghted addltlon of the two channels can be lmproved by evaluating HD decoder lnformatlon, i.e. lnfor-matlon on the transmlsslon mode, the quantlzlng status or the motlon of the lmage block.

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Claims

1. A system for processing television-type video signals, comprising a source of wide bandwidth high definition video signal containing temporally and spatially high resolution image informa-tion;
means responsive to said high definition signal for pro-viding a first video signal having a given temporal resolution and standard spatial resolution less than that of said high definition video signal;
means responsive to said high definition signal for pro-viding a second video signal having temporal resolution less than that of said first video signal and spatial resolution greater than that of said first video signal;
a first channel for conveying said first video signal;
and a second channel for conveying said second video signal.

2. A system according to Claim 1 wherein each of said first and second channels exhibits a band-width less than said wide bandwidth of said high definition video signal; and said first video signal is compatible with a standard television receiver.

3. A system according to Claim 1, wherein said second channel conveys no more than every other (2n-1) image scan derived from said high definition video signal.

4. A system according to Claim 2, and further including means for reducing the data content of said second video signal prior to transmission.

5. A system according to Claim 1, and further including means for encoding at least one of said video signals conveyed by said first and second channels with information con-cerning the mode of video signal encoding and with motion vector information.

6. A receiver system responsive to first and second video signals conveyed by first and second channels respectively, said first video signal having a given temporal resolution and standard spatial resolution less than that of a high definition video sig-nal; said second video signal having a temporal resolution less than that of said first video signal and spatial resolution great-er than that of said first video signal; said receiver system comprising signal formatting means for providing a non-interlaced video signal with enhanced resolution compared to a standard television signal.

7. A system according to Claim 6, wherein said formatting means includes field dependent line pro-cessing and interpolation means.

8. A system according to Claim 6, further including means for converting the scanning rate of received sig-nals.

9. A system according to Claim 6, comprising decoder means for decoding received signals to develop motion vector information signals associated with image blocks to be reconstructed to produce an overall image; and image regeneration means responsive to signals including said motion vector signals from said decoder means for regenera-ting an image.

10. A system according to Claim 9, wherein said image regeneration means develops an image signal with an increased image scanning frequency in response to motion vector information.

11. A system according to Claim 10, wherein for generating a given image block (2n) said image re-generation means shifts an image block (2n-1 or 2n+1) adjacent to said given image block in response to approximately one-half the value of said motion vector information.

12. A system according to Claim 10, wherein for generating a given image block (2n) said image re-generation means shifts image blocks (2n-1; 2n+1) adjacent to said given image block in opposite directions in response to approxi-mately one-half the value of said motion vector information and interpolates said shifted image blocks on a pixel-by-pixel basis.

13. A system according to Claim 10 wherein received video signals contain intraframe coded image blocks; and for generating a given image scan block (2n) said image regeneration means averages pixels of intraframe coded image block (2n-1) adjacent to said given image block with pixels of corres-ponding intraframe coded spatial image block (2n+1) adjacent to said given image block.

14. A system according to Claim 8 comprising:
means for combining signals from said image regeneration means and signals from said signal formatting means to produce a combined signal;
a signal weighting circuit responsive to said combined signal for providing first and second weighted output signals;
a first signal multiplier responsive to an output signal from said signal formatting means and to said first weighted out-put signal;

a second signal multiplier responsive to an output sig-nal from said image regenerating means and to said second weighted output signal; and means for combining output signals from said first and second signal multipliers.

15. A system according to Claim 14, wherein gray-scale differences associated with a given image are summed on an image block basis using an n x n pixel window; and a weighting factor is determined for pixels of said image.

16. A system according to Claim 15, wherein an image information generated from said non-interlaced signals from said formatting means is multiplied by a first weighting factor (a) for each pixel; and image information from said regeneration means is multi-plied by a second weighting factor of (1-a).

17. A system according to Claim 16 wherein said first weighting factor (a) is equal to unity if the weighted sum of absolute gray-scale differences exceeds a given threshold.

18 18. A system according to Claim 17, wherein below said threshold the value of said first weighting factor (a) increases proportional to the weighted sum of absolute gray-scale differences.

19. A system according to Claim 15, wherein said weighting factor is a function of the video signal transmission mode, the status of video signal quantization or motion information.

20. A system according to Claim 6, wherein signals received via said second channel contain infor-mation relative to the information content of said first channel.