DE2365545A1 - Transmission system with source of coded colour TV signals - signal has luminance and three colour difference components - Google Patents

Abstract

The colour television signal contains a luminance component, three colour different components and a reference component. Signals are coded in the three line sequential of specified form. These signals produce the luminance signal. A converter is connected to the signal source and controlled by the reference component which converts the above signal into a form suitable for application to a colour t.v. receiver. The converter consists of oscillations generating means, and of delay lines in order to convert the sequential signals into a simultaneously available modulated form. The invention enables a narrow band transmission system to be used while giving improved vertical picture resolution and more natural colour.

Description

PATENT LAWYERS Dr. - Inn. I ·! 'NS Ri ⁵ HHHKE Dip! .-- i-. _t :. :; ■: .. τ \ ü VHKE

₇ .ο Οφ1 · - «* Ξ · MZ-NSi. RUSJHKE

~ ° ~ 1 BERLIN 33

Äuguste-Viktoria-Strasse 65

Zenith Radip Corporation, Chicago, 111. U.St.5.

Line sequence color video coding with the same luminance proportions

The present invention relates to video signal systems, and more particularly an improved video capture system and method for coding video signals.

For some time now, interest in video recording and playback systems. In order for such a system to be accepted by the public it must necessarily be Be economical and easy to use, provide high quality images, and be compatible with existing television receivers. Furthermore, it should be on a cheap one Storage medium - preferably on such an economical one Solution like a plastic disc. This medium is for the Consumer market particularly suitable as it is low cost, lightweight Manufacturability and a format that most consumers are familiar with.

One of the problems posed by storage media is the bandwidth required to achieve a true color reproduction of color television signals. In the NTSC system, for example, the color subcarrier for the color information is at the upper end of the luminance band, ie at 3.58 MHz, which means that a bandwidth of at least k MHz is required in order to achieve a normal

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reproduce composite color television signal. Ldird the Limited bandwidth, the higher-frequency information components suffer; the Farbuiede'rgabe is impaired or even completely prevented.

Wake up one of the l / experienced the prior art that meant to do so are to overcome this difficulty becomes an electronic one Commutator used, which sequentially generates signals in the low-frequency parts of the available transmission band, the every third row of the three primary colors red (R), blue (B) and green (G) represent. These signals are sent with a continuous high-frequency luminance signal combined in the high-frequency band part. In this way, the color fidelity essentially retained, and impairments 'due to bandwidth limits appear as loss of image detail' (In the transition from a simultaneous to a line sequence system, there is of course a loss of vertical resolution; this loss can, however, be regarded as justifiable).

In the decoder of this system, the color sequence signals are by means of two delay lines connected in series are delayed in such a way that all three color signals are available at any given point in time; they issue the color information adjacent lines of the image. Three commutator switches switch the row sequence signals optionally to assigned inputs of a matrix, where the signals according to their contribution can be combined again to form the luminance signal in order to obtain the low-frequency part of the luminance signal.

E.g. is the luminance signal Y of the image in the IMTSC system according to the relative proportions of the primary colors defined as

Y = o, 3o R + o> Π B + o, 59 G.

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While the luminance signal can be reconstructed by combining R, B and G in these ratios, this leads -Überujiegen the green signal to the fact that the luminance signal this Signal follows. As a result, there is a delay in the response to a change in brightness in the image until the next G line sequence signal which increases the vertical resolution of the displayed Picture continues to deteriorate.

Assume that in a 525-line, double-interlaced IMT SC system, the lines jp of the image are numbered consecutively and are transmitted in the order R, B, G; the result is the sequence R, B, G ₃ , R ,, B, G etc. During the first line, Y. can thus be expressed as o, 3o FL; Y "during the second row as o, 3o R. + o, 11 B; Y during the third line as o, 3o R. + ..o, 11 B _? + o, 59 G ,. Correspondingly, Y, = d, 3o R, + d, 11 B + α, 59 G and Y _g = n, 3o R, + o, 11 B ₅ + o, 59 G ₃ apply. As can be seen, Y ₃ , Y ^ and Y contain the term ο, 59 G, with significantly lower red and building components and are therefore essentially the same. In contrast to the high proportion of green in the luminance, this follows the G-signal and essentially only appears to change in every third line when new G-information is available. This fact impairs the vertical resolution, since abrupt luminance transitions can occur in the original image, but are fully reproduced by the system when the next subsequent green scan takes place.

Another prior art system provides that instead of a signal Y, a signal M made up of equal proportions of van R. B and G produces:

"M = 0.33 R + o, 33 B + o, 33 G.

However, this system does not achieve correct luminance levels and leads to incorrect playback in many situations.

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It can be shown that a system which uses M instead of Y Blue and magenta with near luminance and desaturated, green and yellow, however, with low luminance and oversaturated.

So it is the general aim of the present invention to provide a specify new method for coding color television signals.

In particular, it is an object of the present invention to provide a specify improved VidED recording system for FFs signals.

Another object of the present invention is to provide a novel method for encoding FFd signals -ier for schmnlbanrire i ^"+ _raf: be ufigsEysteme 'ierbesserter indicate vertical image resolution and color fidelity.

According to the present invention, there is a method and an arrangement intended for the coding of FFS signals of the type in which a first, a second and a third color difference signal and a luminance signal which represents the fluctuations in brightness of the picture elements are present. Wake up Method, the first, the second and the third color difference signal are cyclically combined individually with the luminance signal, a first, a second biaw. to generate a third line sequence signal whose relative amplitudes according to algebraic Addition in equal proportions only results in the luminance signal. ! Mach the invention is further decoded by gives the subsequent signals to delay means in order to make them available at the same time, and matrices them in equal proportions, to derive the luminance signal for further processing.

The novel features of the present invention are particular laid down in the claims. The invention can be combined with other features and advantages - best below

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Refer to the accompanying drawing to understand where it is around a block diagram of an FFS signal coding and decoding system acts according to the present invention.

The drawing represents the invention in the black diagram as a complete one System for coding and decoding FFS signals The connection between the coding and the The decoding stage can, for example, be a transmission line such as e.g. a telephone line, a radio corner or a storage medium be like a magnetic tape or a vinyl record. On the transmission or studio side, a camera 10 generates three conventional ones Primary color signals R, G and B, die.die luminance and Contains color information of the assumed image scene. DiBse Signals are given to a matrix circuit 11, ωο them can optionally be linked to one another in order to produce a luminance signal Y, which contains the brightness information, and to generalize it Color difference signals K (C - Y) and K (C - Y) with the chrominance infDrmation. In these expressions

are K and K, constants and (C. - Y) and (C - Y) the veralla D ι C-

mean color difference components. The color difference signals go on two low-pass filters 13, 1A- that only have video frequencies below let through about Gao kHz. This can be known multi-section filters with suitably selected and dimensioned Act impedance elements that reach the desired Goo kHz limit.

The output signals K (C, - Y) and K, (C "- Y) _{1 of} the filter

at Tue-L

13 and 14 (the subscript L denotes a low-frequency component) each go to one of the two phase reversal stages 15 and 1G, which invert the signals so that at the outputs of stage 15 the signals + K (C, - Y). and -K (C.-Y).

al L to L

^{and the signals + K} b ^(C 2 - ^Y V and -K _b (C ₂ - · Y) _L are correspondingly present at the outputs of stage 16.

The third low-frequency color difference signal is used in the study

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fs 12 from the negatives of the signals K (C. - Y). and ¹ OC - ^γ ) | _ formed. These signals go to a commutator 17, which is shown schematically as a mechanical three-segment switch with a rotating tap arm. In practice, this is an electronic switch made up of three active switching stages or the like. With a corresponding control circuit, which derives the desired switching method in 12d segments from an applied control signal.

The commutator 17 is controlled by a control circuit 18, the hsptii. has a corresponding number of frequency divider stages in order to derive the switching frequency desired for the commutator from the line sync pulses. In practice, the commutator is controlled in such a way that its switching frequency is one third of the line frequency and the signals ^H a ^CC 1 " ^Y) L ' ^K b ^CC 2" ^Y) L ^SDuie " ^H a ^(C 1" ^Y) L " ^H b ^(C 2 " ^Y) L are scanned every third line. The resulting line filler signals are therefore for each of the 175 groups of three lines each in 525-line IMTSC format in the form K (CY) ,, ^H b ^(C 2 " ^Y) L ^and " ^K a ^(C 1 " ^Y) L " ^H b ^(C 2" ^Y) L ^VOT '

This signal will be sent to the adding 19 GB video amplifier, by adding it to the luminance signal Y generated in the matrix 11 with the full frequency range. HiEroei surrendered line sequence signals E of the general form S, S and

away

S to
c

= γ ₊ K _a (C ₁ - Y) _L

= Y + Kb (C ₁ - Y) _L

-.Y) _L

Since each generalizing color difference signal is a combination expressing primary color difference signals, lets, and zuar particularly R-Y and B-Y, it follows that

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S _a = Y + H ₁ (R - Y) - H ₂ (B - Y)

Su = 'V + ^ (R - Y) + H. (B - Y) b 3 4-

S = Y + H _c (R - Y) + H _r (B - Y)

C 5 b

According to the present invention, the line sequence signals weighted according to the relationship S + S + S = 3Y. Furthermore are the system parameters sn won that

K "+ H-. + H _c = U and K, + K, + ι L = D 1 j ο c η b

It follows that H ₅ = - (H _-1 + H ₃ ) and H ₅ = - (H ₂ + and the third line sequence signal results in sioh to

= Y - (H .. + H ₃ ) (R- Y) - (H ₂ + H ₄ ) (B - Y)

These signals are given to the adder 2o, ωο dem final video signal, the lines and image sync pulses from a conventional syncbron pulse generator .21 are impressed. The sync pulse generator also provides (via not shown Means) for the synchronization of the camera and supplies the line synchronization pulses as a reference signal to the Hommutatoransteuerschaltung 18, in order to ensure the line-synchronous operation of this circuit part.

After adding the sync pulses, the signal can be transmitted over a narrow-band channel without the color fidelity suffering significantly, since the color information is now below 60b kHz instead of 3.58 MHz as in a conventional IMTSC FFS signal. The block 5d referred to as "transmission medium ¹¹ " can therefore be a wire cable, a radio link, a magnetic tape, a vinyl disk or any other suitable transmission or transmission medium

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-B-

Be storage device. As can be seen, one requires Radio link a carrier modulator and a suitable receiver, a vinyl record with a suitable playback device Playback head, usuj. The same can be said of tapes and video disks it may be desirable to have a carrier with the line sequence signals frequency modulating and storing the modulated carrier on tape or disk to avoid recovery problems to avoid the signals. The system parts for modulating the television signals on the carrier are not shown in the present embodiment, since the corresponding V / experience and circuit arrangements are known.

After the sequential television signal over the transmission medium Once it has run, it must be converted back into a form in which it can be given to an FS receiver. While it is assumed here that the normal receiver is for a (WTSC-FFS signal is set up, (the normal receiver for a) I \ ITSC-FFS-Signal is set up, this does not necessarily have to be done to be the case, since the subsequent signal can be post-encoded for use within any type of FS receiver. However, the following description relates to receivers that are switched to receive WTSC-FFS signals.

The low-frequency components of the line sequence color signals pass through a low-pass filter 22 which, like filters 13 and 1A in the encoder, only allows video signal components below 600 kHz to pass. These low-frequency signals are fed to stage 23, a 3.58 HHz oscillator and amplitude modulator, where a dart generated carrier with a frequency of 3.58 MHz is amplitude-modulated with the color signals in a conventional symmetrical modulator. The resulting modulated 3.58 MHz signals are applied to two series-connected delay lines IU, 25, which delay the 3.58 MHz signal by one line length or 63.5 microseconds in order to allow each of the line sequence signals to be matrixed in simultaneously having the low frequency part of an NTSC video signal available like it

5098 3 1/03 29

has been described below.

The undelayed output signal of the modulator 23 udrd is first given directly to a first chrominance amplifier 28, which is preferably a conventional NPIM transistor with both collector and emitter output in order to generate two signals in opposite phase. In a corresponding manner, the single delayed output signal of the delay line Zk goes to the supplied chrominance amplifier 27 and the doubly delayed output signal of the delay line 25 goes to a third chrominance amplifier 26.

The collector of the transistor of the chrominance amplifier 25 is located at a DC bias potential through resistor 26a; its emitter via the resistor 26b ah ground. Correspondingly, the resistors 27a, 27b on the one hand and 28a, 28b on the other hand provide the conventional bias supply for the Collectors and emitters of the transistors of the chrominance amplifiers • 27,28. '

The inverted output signals of the amplifiers 26 ... 28 are applied to the arms of one of three coupled commutator switches 29 ... 31. In order to understand the function of these switches, it is first necessary to explain the function of the delay lines Zk, 25, which make each of the sequentially transmitted 3.58 MHz color signals available in the receiver at the same time. ,

Assume a coding in the form S, S and S as well as numerical indices to identify the deflection line. At the beginning of line 10, the signal S appears at the output of the modulator 23, the signal S "at the output of the delay line 23 and the signal S" at the output of the delay line 25. One line later, S ^ _{1 appears} at the output of the modulator 23, S . at the output of the delay line Zk and S "at the output of the delay line

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- 1α -

line 25. Another line later is the arrangement Ξ ,. , S ₁₁ and S. etc. At the beginning of line ka the sequence is S,, S-, „, S, r ,; and at the beginning of line 5o it is S, Ξ, “, Ξ, so three color difference signals are available at every moment, but not at the same corresponding point. The Kc mutator switches 29 ... 31 now switch the outputs of the amplifiers 26 ... 28 to the corresponding connections 32 ... 3k, so that each connection is assigned to a single color difference signal. If primary color difference signals are used for coding, a useful sequence could look like this, for example:

S = Y + K (R - Y) ₁ aa L

S = Y + K, (R - Y),
bb L

S = Y-K- (R-Y) ₁ -K, (R-Y). ca L b L

In a typical time slot arrangement, S would appear in the lines

% ^ j 7, 1α etc. appear, S, in lines 2, 5, S, 11 etc. and Ξ in lines 3, 6, 9, 12 etc. In this situation, a switching phase of the commutator 29 is provided, in which the output of the amplifier 25 is switched through while the Q. Correspondingly, the commutator switches 3d, 31 switch the output signals of the amplifiers 27 and 28 to the terminals 32 ... 3k, so that there are always color difference signals of the prescribed type.

The commutator switch must fulfill its function 29 ... 31 always work synchronously with their counterpart, the commutator switch 17 in the transmitter or encoder. To this end a synchronous clipper circuit 36 is provided, which consists of the

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received Sianal derives the image and line sync pulses. These sync pulses are applied to the commutator control circuit 37, which divides them down and for synchronization of the three. Commutator switch exploited. It has to be here Again, it should be emphasized that the commutator switches are only used for clarity Representation are shown as mechanical rotary switches; in fact, fully electronic switching means would be used.

Furthermore, a system of line identification is required, to ensure that the commutator switch 29 always the correct line sequence signals to the assigned connections. For this purpose, the switching sequence in the hoder and made the same in the decoder, and each field starts with the same generalized color difference signal. This simplification allows the frame and line sync pulse only to "initiate" the function of the commutator switch to use.

A useful group of sequence signals is

S ₃ = Y ₊ I (RV)
^s b = ^Y - i ^(B - ^Y)

S _c = Y - II (R, Y) - ^ (B - Y) = Y + (B - Y>.

Here the (G - Y) signal is generated during the encoding, lilie will, however, have to be seen in the implementation of the signal into an NTSC signal with subcarrier the amplitudes must be changed and line identification must be provided.

However, if the following coding parameters are used, line identification of any kind is superfluous.

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With symmetrical coding you get:

S = Y ₊ o, 877 (R - Y)

S = Y- D, «8 (R - Y) + D, 427 (B - Y) S = Y- o.43B (R - Y) - o.427 (B - Y)

As can be seen, these signals are the result of demodulating an IMTSC subcarrier on three ^{axes offset from one another by 12o D} with the same gain (one axis corresponds to RY).

The non-inverted output signals of the matrix amplifier 26 ... 28 lie on a first matrix circuit of individual same Matrixuiderständen 38 ... Ua and a common terminal if 1, which is connected via a resistor 42 to ground. In a line sequence coding according to the present invention, equal components of the three low-frequency color difference signals can be combined in order to generate the low-frequency luminance signal. This takes place through the resistors 38... 4o, and the low-frequency luminance signal Y is above the resistor 42.

The low frequency luminance signal developed on a 3.58 MHz carrier Via the common emitter resistor 42, the inverted signals in the collector output circuits of the Transistors 26 ... 28 subtracted. As a result, the component Y ^ stands out, so that only the color difference components of the signals - amplitude modulated on a 3.58 MHz carrier - are left over, placed on switches 29 ... 31 and on the connections 32 ... 34 can be switched. These signals then arrive at the matrix 35, in which they have a predetermined relative phase and Amplitude to an NTSC chrominance signal of the format D, 877 (R-Y) cosiut + o, 493 (B-Y) sino-t are put together. Are the Line sequence signals according to the preferred execution

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farm coded, it can be seen that the matrix 35 mw needs to contain suitable phase shifters for two of the color difference signals, but not amplitude-changing switching means.

The Y signal consists of an amplitude modified 3.58 MHz carrier and must be demadulated by means of a detector 43 (which is a common envelope modulator ader an equivalent circuit can act), a rekambinatian with the primary color difference signals in the matrix intensifier 44 can take place.

The high-frequency luminance signal component Y ^ of the ahne line sequence division, ie transmitted unswitched, is extracted with a high-pass filter 45 and fed to the input of the matrix amplifier 44 via a deceleration line 4S. The high-pass filter prevents low-frequency Zeilertfall signals from bypassing the circuit via this path, which would cancel the recombination by the commutator switches 23 ... 31, the matrix 35 and the matrix amplifier 44. The delay line 46 compensates for the slightly extended duration of the signals in the low frequency channel containing said low pass filter 22 and (matrix amplifiers) the delay lines 24 _r 25th Furthermore, the image and line pulses are also added in the matrix amplifier 44. Appropriate clerical and jarring hold circuits can also be provided at this point to condition the signal for optimal repeatability.

At the output of the matrix amplifier 44 there is a video / erhundsignal according to the WTSC-E \ lorm, which is sent to the FS-Erapfängerschalteng 4? is given; Here it may be a herkömntlichen FS receiver. There the composite signal is amplified and demodulated _{f in} order to obtain the video signals required for controlling the picture display tube 4B. While here that to the recipient 4? If the signal supplied is specified as a video signal, it can also be used to modulate an RF carrier

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, which then ule a normal television signal to the antenna input of the recipient can be placed.

The present application therefore discloses a process and an arrangement for coding color television _{signals for} which color television signals are offered in a narrow-handed transmission system with tsinlffial impairment of resolution and color fidelity.

The invention is explained below in the context of the i \ iTSC-Blldfarraats üEtrden. ! which can, however, also be seen by others Television standards - such as PAL and SECAH - use, if you can Switching and mutual assignment of the Systeratelle accordingly changes.

Mährend the invention has been described with reference to particular embodiments, it is apparent to the skilled person, however, _r that make it perform various changes without departing from the principle ,, animal invention, they ωϊε In the appended claims set forth _r abzudeichen. The claims are therefore intended to encompass all changes that fall under the concept of the present invention.

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Claims (1)

Claims Fa.) Transmission system with a source of coded color television signals with one luminance component that corresponds to the brightness of the scene, three color difference components that correspond to the color content of the scene, and a reference component, the signals in three-line sequence signals of the form Y ₊ H (C. - Y), Y + K, (C ₉ - Y) and Y + H (C ^ - Y) are coded, where K, K, and K are constants and so chosen ' away . c are that the subsequent signals result in the luminance signal on average; and with a conversion device connected to the source and working under the control of the reference component, which converts the signals encoded in line sequence into a color television signal suitable for connection to a color television receiver. 2. Transmission system according to claim 1, in which the following applies: (C ₁ - Y) = H ₁ (R '- Y); (C ₂ -Y) = H ₂ (B-Y); and (C ₃ -) = -H. (R - Y) - K ₉ (B - Y), where K and H _{9 are} constants. 3. Transmission system according to Claim 2, in which: HH. = 3o / 59 and H, H ₉ = 11/59.
al b f ■ H. Transmission system according to Claim 1, in which the conversion device consists of vibration-generating means and delaying means in order to simultaneously make the following signals available in modulated form. 5. Transmission system according to claim k, wherein the vibration generating means have a frequency that of the 5098.3170329 corresponds to the color subcarrier auxiliary frequency required by the television receiver. 6. Transmission system according to claim 5, which further comprises a matrix device and a switching device, the latter being the simultaneously available madulation signals under control by the reference component for the purpose of connection to the matrix device selects · » 7. Transmission system according to claim G, wherein the luminance component of the switching device in modulated Shape is obtained and which furthermore has a detector, which demodulates the luminance component, and an arrangement which interconnects the output signals of the detector and the matrix circuit connected. 8. Transmission system according to claim 6, wherein the Luminance component at the source is a continuous high frequency And the color difference aale the lower Make up part of the total bandwidth. 9. Transmission system according to claim 8, wherein the conversion device a high-pass filter, which is connected to the circuit, to the high-frequency luminance component to bypass the switching means. 10. V / experience for coding a color television signal, by A. A variety of primary color signals are generated, each with a specific color characteristic of the Image scene correspond; B. generates a luminance signal from selected parts of the primary color signals; and 509831/032 C. the signals are coded into three filling signals, each consisting of the sum of the luminance signal and of a color difference signal, the algebraic addition of equal proportions of the three Follow-up signals result in the luminance signal. 11. Uerfahren according to claim 1o, uabei in step B the Primary color signals are matrixed to form a pair of color difference signals and derive the luminance signal. 12. 'The method according to claim 11, in the case of dsm Color difference signals is primary color difference signals. 13. The method of claim 12, further comprising processing the two primary color difference signals and the two processed signals are used to obtain a third color difference signal. 14. The method according to claim 13, wherein the three sequence signals by switching the color difference signals and adding them of the luminance signal generated. 15. The method of claim 1 ^, wherein the primary color difference signals are the (R-Y) and the (B-Y) signals. 16. The method according to claim 15, with the following sequential signals: = Y ₊ Ii (B -Y) ^{= Y} - | § ^(R - ^Y) ~ U ^CB - ^Y) 509831/0329 17. The method of claim 11, wherein the color difference signals make up the lower low-frequency part of the luminance signal band. 18. V / experience according to claim 17, wherein the bandwidth is less than h MHz and the low-frequency part is below about 6üd kHz. 19. A system for encoding and Deküdierung van F _a rbfernsehsignalen in Farm van color difference units, which primarily corresponds to the color content of an image scene, and a luminance component corresponding to the brightness of the image scene, means which combine the color difference components cyclically with the luminance component in order. to generate line-sequentially coded signals which, after algebraic addition, leave only the luminance component in equal parts; with signal transmission means; with means which apply the line-sequentially coded signals to the signal transmission means; signal delaying means connected to the signal transmission means for making the line sequence signals available simultaneously; and with a first matrixing device which combine the same proportions of the simultaneously present line sequence signals in order to obtain the luminance proportion. 20. The system of claim 19, further comprising zuJBite matrixing means which the color difference components linked in order to gain a chrominance component, as well as a third matrixing device, which the chrominance component with the Luminance component linked to obtain a composite color television signal. 21. System according to claim 2o, with a carrier frequency generator, wherein the delaying means contain a modulator, which the line sequence signals to the output signal of the 609831/0329 Modulate tear frequency generator, as well as two connected in series Delay lines which delay the resulting modulated carrier signals, the first matrixing means contains a detector, which from the with the line sequence signal modulated carrier signal derives the luminance component. 22. - System according to claim 2o, in which the frequency band of the luminance component is significantly wider ίε-t than the frequency band the color difference components. 23. The system of claim 22, wherein the by the
first matrixing device derived luminance component only
Contains frequencies below a predetermined cut-off frequency and which has a high-pass filter which is connected to the transmission device and only those above the cut-off frequency
lying portions of the luminance signal are on the third matrixing device. 509831/0329 Blank page