CA2065851A1 - Tv transmission system - Google Patents
Tv transmission systemInfo
- Publication number
- CA2065851A1 CA2065851A1 CA002065851A CA2065851A CA2065851A1 CA 2065851 A1 CA2065851 A1 CA 2065851A1 CA 002065851 A CA002065851 A CA 002065851A CA 2065851 A CA2065851 A CA 2065851A CA 2065851 A1 CA2065851 A1 CA 2065851A1
- Authority
- CA
- Canada
- Prior art keywords
- picture
- spectral components
- dct
- frequent
- signal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N11/00—Colour television systems
- H04N11/06—Transmission systems characterised by the manner in which the individual colour picture signal components are combined
- H04N11/12—Transmission systems characterised by the manner in which the individual colour picture signal components are combined using simultaneous signals only
- H04N11/14—Transmission systems characterised by the manner in which the individual colour picture signal components are combined using simultaneous signals only in which one signal, modulated in phase and amplitude, conveys colour information and a second signal conveys brightness information, e.g. NTSC-system
- H04N11/16—Transmission systems characterised by the manner in which the individual colour picture signal components are combined using simultaneous signals only in which one signal, modulated in phase and amplitude, conveys colour information and a second signal conveys brightness information, e.g. NTSC-system the chrominance signal alternating in phase, e.g. PAL-system
- H04N11/167—Transmission systems characterised by the manner in which the individual colour picture signal components are combined using simultaneous signals only in which one signal, modulated in phase and amplitude, conveys colour information and a second signal conveys brightness information, e.g. NTSC-system the chrominance signal alternating in phase, e.g. PAL-system a resolution-increasing signal being multiplexed to the PAL-system signal, e.g. PAL-PLUS-system
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N7/00—Television systems
- H04N7/007—Systems with supplementary picture signal insertion during a portion of the active part of a television signal, e.g. during top and bottom lines in a HDTV letter-box system
Abstract
(57) Abstract In a TV transmission system which operates on the "letter box" principle for transmitting the 16:9 aspect ratio, every fourth line is removed and transmitted in a compatible form as additional information at the upper and lower edges of the picture with the 4:3 formal. This process, however, leads to signal jumps and distorted movements and to reduced vertical definition in the 4:3 receiver and to greater sensitivity to noise in the 16:9 receiver. These drawbacks are largely overcome, and in particular the static definition of the 4:3 receiver is maintained, by using a vertical DCT or length eight and an inverse DCT of length six in the encoder or the transmitter and vice versa in the decoder of the 16:9 receiver.
Description
2~ 5~.
H89/081P2*HA-120691 - 1 -Method, coder and decoder for transmission and for compatible reception of standardized television signals The invention concerns a method,a coder and a decoder for the transmission and for compatible reception of standardized television signals.
For the introduction of a 16:9 broad picture format into existing television standards (e.g. PAL, SECAM, NTSC) with the format 4:3 the so-called 'letter-box' method is being discussed ("Verbesserungsmoglichkeiten und Entwic~lungstendenzen bei PA~" (Possible improvements and trends for development with PAL), G. Holoch, lecture FKTG
Jan. 17, 1989 in Berlin, and "Kunftige Fernsehsysteme"
(Future television systems), F. Muller-Romer, Fernseh- und Kinotechnik, Vol. 43, issue No. 6/1989, and "Die neuen Wege de alten PAL" (New ways of the old PAL), Dr. A. Ziemer, E.
Matzel, Funkschau issue No. 18/1989). With these methods the total picture information of the 16:9 recording is represented on the 4:3 receiver in a compatible way with bars at the upper and lower edge of the picture that are not filled with visible picture contents.
This is performed in that in the studio every fourth line of the, for example, 575 active lines in the frame is taken out of a 16:9 picture with, for example, 625 lines and certain lines are tran~mitted as additional information in the bars that are hereby being left above and under the active picture. The active picture in the 4:3 receiver then comprises 431 lines and the edge bars each comprise 72 lines. This mode of presentation of, for example, movies with a 16:9 format in the 4:3 receiver has also been in use before and thus requires no adaptation on the side of the viewer.
Because the ratio of the two picture formats corresponds with the ratio of the original to the reduced REPLACEMENT SHEET
,. . , ., - , : ~ ~
.. . . . .
,, ~. ., 2~ Xl H89/081P2*HA-120691 - 2 -number of lines the geometrical distortion through the taking out (removal) of the lines is compensated.
The 16:9 receiver now evaluates the information fro~
the two edge bars in order to increase the number of active lines which has been reduced to 431 to 575 again and, thereby, to create a 16:9 picture covering the complete format.
If every one out of four lines is taken out of the 575 active lines in the fra~e, however, signals jumps are created in the 4:3 receiver which become visible in particular with diagonal or moving structures in the picture contents. In order to avoid signal jumps the lines can also be vertically interpolated in the transmitter. This, however, usually leads to a reduction in the vertical resolution in the 4:3 receiver.
In order that the picture contents of the lines in the edge bars does not appear in any disturbing way in the 4:3 receiver the amplitude of these picture contents are lowered (reduced) in the transmitter by about 13 dB and re-elevated accordingly in the 16:9 receiver. This can lead, however, to a markedly increased noise in the 16:9 receiver and, thereby, to a diminished picture quality compared with a 4:3 receiver that is today's state of the art.
In "Compatible HDTV coding for broadband ISDN", K.H.
Tzou et al., IEEE Global Telecommunications Conference &
Exhibition, Hollywood, Nov. 28, 1988, volume 2, pages 24.1.1 through 24.1.7, a method for digital coding and transmission of EQTV signals in ISDN networks is decribed in which the EQTV picture i9 extracted, with the help o~ a two-dimen~ional DCT, in reduced definition from an HDTV picture, digitally coded and transmitted in data reduced form. In an auxillary channel additional information are transmitted by means of which the HDTV picture can be reconstructed again in a high definition ISDN receiver. Hereby, picture REP~ACEMENT SHEET
'' '. ... .. ~ : ' i :: ` .
2~ .51.
H89~081P2~HA-120691 - 3 -sections of a 16:9 picture exceeding the 4:3 format are also transmitted in the auxillary channel.
Hereby, a 4:3 EQTV receiver only reproduces part of the 16:g picture contents.
It is the object of the invention to name a compatible transmission system for a 16:9 television signal using a standard television channel which supplies pictures in the letterbox format in 4:3 standard receivers and pictures in the 16:9 format in improved 16:9 receivers, in particular with a vertical resolution corresponding with the ori~inal signal and with a low noise rate.
This task is solved by the features given in claim 1.
Advantageous further developments of the invention are given in the subclaims.
First of all, at the side of the transmitter the television signal with the 575 active lines of the 16:9 picture is digitalized and in the frame specially filtered in the vertical direction. This can be performed by, for example, a DCT transformation (DCT: direct cosine transform) with the length eight.
Of the always eight coefficients generated always the first through fifth and the eighth are combined. These six coefficients are inversely DCT transformed with the length six, digital-to-analog converted and inserted at the respective position in the compressed 16:9 picture. Hereby, the 4:3 receiver has virtually the full vertical resolution.
The sixth and seventh coefficient are also digital-to-analog converted and transmitted in the bars above and below the compressed 16:9 picture.
A 4:3 receiver does not evaluate the coefficients in the two bars but presents the television picture according to the above described 'letter box' method. Because it is a characteristic effect of a DCT transformation that the signal energy is concentrated in the coefficients of lower order, the sixth and seventh coefficient usually have but small amplitudes. Through this, in a 4:3 standard receiver REPLACEMENT SHEET
the visibility of disturbing picture contents in the bars is reduced already. It is sufficient if these parts of the signal are reduced only slightly or even not at all. The advantageous result is that there is virtually no noise increase in the 16:9 receiver.
Instead of a linear reduction the amplitudes of the coefficients in the bars can be reduced using a non-linear function.and be inversely-re-elevated correspondingly in the 16:9 receiver, in order to reduce their-visibility in the 4:3 receive~ even further; Through the non-linearity of the .
reduction and elevation (greater amplitudes are reduced to a greater extent than smaller) an increase of noise in the 16:9 rec~iver .is even smaller than wlth a linear reduction and re-elevation.
An improved receiver with a picture format of 16:9 contains a decoder which evaluates the.additional information from the two edge bars and.supplies a full-format 16:9 picture. Herefore, the received television signal is digitalized, DCT-transformed with length.6 vertically in the frame; always the sixth coefficient shifted to the eighth position, the respectively corresponding sixth and seventh coefficient from the edge bars inserted at the sixth and seventh position, the so re-gained original eight DCT coefficients inversely DCT
transformed and inserted at the original positions as in the original signal. Following subsequent digital-to-analog conversion the 16:9 picture is available with full vertlcal resolution and only minimally increased noise~
Subsequently, an example embodiment of the invention is illustrated by means of the drawings. These show in:
Fig. 1 A picture in the format 16:9 ..
, .: : ,, .
- ., . .: . . . :
5~.
Fig. 2 The picture from Fig. 1 with vertically compressed active part and additional informa~ion in the two edge bars (known) Fig. 3 Representation of the active part of the picture from Fig. 2 in the 4:3 receiver (known) Fig. 4 Block circuit diagram of a 16:9 coder Fig. 5 Block circuit diagram of a 16:9 decoder Fig. 6 A dark part of the picture moving in the i horizontal direction in front of a light background Fig. 7 Average distribution of energy in the coefficients of a DCT with length eight Fig. 8 A coefflcients energy distribution in the compressed picture signal in a case of dvnamical picture contents Fig. 1 shows a television picture in the picture format 16:9 as lt is generated in a 16:9 studio, showing a circle.
Fig. 2 shows how the television picture from Fig. 1 is vertically compressed in the area 20 by a known 16:9 coder.
By way of vertical compression by the factor 4/3 431 lines are generated out of the 575 active lines in Fig. 1 as the active picture part 20 for the 4:3 receiver. This compregsion i9 performed by removing every fourth line from the picture from Fig. 1 or by means of a vertical interpolation. Through the compression the geometry of the circle has been altered. The lines removed from the part 20 of the picture or, respectively, the lines required for the U 0~1 ~t'\01 , ~ , , : , :,,: i ~ i .
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: - ` ' ' , ` :' "~ .
2~
decoding in the 16:9 receiver are transmitted in the two edge bars 21 and 22 as an additional signal.
In Fig. 3 it is shown that a 4:3 receiver reproduces the active part 20 of the picture from Fig. 2 in the area 30. Through the horizontal compression of the 16:9 format to the 4:3 format by the factor 4~3 the original geometry of the circle from Fig. 1 is re-established; A viewer is able to see the fUll picture contents from Fig. 1, however, the vertical resolution is reduced and there are black bars 31 and 32 at the upper and lower edges of the picture. In order that the additional signal contained in the bars does not become disturbingly visible it must be adequately reduced (lowered) in amplitude in the l6:9 coder and be present in the ultra black range (between sync level and black level).
A strong reduction of the additional signal, however, leads to a compromized signal-to-noise ratio in the 16:9 receiver due to the superimposed channel noise. This additional noise is contained in the picture signal in the local area.
In a 16:9 receiver the additional signal in the edge bars 31 and 32 is adequately amplified and formed into a picture as in Fig. 1 together with the active part 30 of the picture in connection with the horizontal 16:9 expansion.
Fig. 6 shows a dark picture part which moves in the~
horizontal direction in front of a light background.
Because in the line interlace method the fields represent different phases of motion, corresponding edges have a 'comb' structure. Now, if for example in such a comb structure every fourth line is removed, clearly visible interference patterns are created in a 4:3 receiver. In order to avoid this effect, a 'clean' presentation in the .~
:
, ,.; j, . . .
, : , . . .~
!
2~
4:3 receiver can be achieved using vertical interpolation filters. Hereby, however, higher vertical parts of the spectrum are cut off which are then unavailable for decoding in the 16:9 receiver; and this leads to a reduced vertical resolution.
From the comb structure it can be seen that for a good picture quality in the vertical direction the highest possible frequencies in the 16:9 receiver ~Eig. 6a) as well as in the compressed signal (Fig. 6b) for the 4:3 receiver must be transmitted.
( By means of a suitable vertical transformation, for example with a DCT, this requirement can be met.
In Fig. 7 the value 72 of an averaye energy content 73 of vertical transformation coefficients is shown dependent on the frequency 71. In the case of a comb structure as in Fig. 6a the highest parts 74 of the spectrum are of mar~edly increased values because the base pattern of the eighth coefficient also has a like structure.
In a DCT of the length eight the part 74 of the spectrum is represented by the eighth coefficient. Through ; a compression by the factor 4/3 the value eight becomes the value six. If the sixth and seventh coefficients are removed from the eight DCT coefficients and the eighth is inserted at the position of the sixth, a comb structure as in Fig. 6b is generated through inverse transformation. A
DCT with the length eight becomes a DCT with the length 9iX.
In Fig. 8 the corresponding spectrum of such a DCT of the length six is shown. Always the sixth and seventh coefficients are transmitted as an additional signal in the bars 21 and 22. In an advantageous way their values are compressed in an non-linear way and inversely expanded - ~ . ~, , ~ - . :
- 8 ~
accordingly in the 16:9 receiver in order to achieve an improved signal-to-noise ratio.
The 4:3 receiver does not evaluate these additional signals. Because, as shown in Fig. 7, the statistic average of the values of the DCT coefficients of higher order are significantly smaller than those of lower order a reduction of their leve~s for the purpose of~avoiding the visibility in the 4:3 receiver is not - or only to a small extent -required.
In an advantageous way the coefficients in the edge bars do not represent picture signals in the local area - as it is the case in the known method - but spectral values of higher frequencies which appear to the viewer as a high frequent noise. Such a noise will naturally be perceived by the viewer as less disturbing than a distortedly presented additional picture content.
Fig. 4 shows the block digram of a 16:9 coder. The television signals in the format 16:9 coming from, for example, a camera are analog-to-digital converted 41 and written into a memory 42. From the memory 42 the scanning values of always eight picture dots lying vertically above each other are continuously read out and DCT transformed in circuit 43. The sixth and seventh DCT coeffiecients are sorted out in circuit 44 and compressed in a non-linear way in circuit 46. This can be performed, for example, by means of the function y = xl/~ (y = x to the power of 1/3) whereby x stands for the input signal and y for the output signal.
The first through fifth and the eighth DCT coefficients are always combined in circuit 44 and inversely DCT transformed with the length six in the circuit 45. The output signals of the circuit 45 and 46 are written into the memory 47 and output as an analog, compatible television signal in the 4:3 format via the digital-to-analog converter 48.
- ,, .:, ~. ,, :.: . -, ' ' ' , : ~ .;, ~, , , ~
2r~
Fig. 5 shows the ~lock diagram o~ a corresponding 16:9 decoder in the 16:9 receiver. ~he signals in the 4:3 format are first converted analog-to-digital in the circuit 51 and written into the memory 52. From here the scanning values of.always six piture dots lying one above the other are read out and DCT transformed with the length six.in circuit 53.
The respective corresponding sixth and seventh-coefficients are fed..from the memory 52 into-the circuit 54 and expanded inversely with respect:to t~e function of the circuit g6,..
i.e. using y = X3 (y = X to the power of 3), in a non-linear way.. In circuit 55 the sixth of the DCT trans~ormed.
.coefficients.is inserted at the position of the originally eighth and the sixth and seventh coe~ficients from-circuit 54 are shifted to the sixth and seventh position. The original eight DCT coe~ficients that.are~re-gained in ~his.
way are inversely DCT transformed in circuit 56 and written into the memory 57. From there they are output as an analog television signal in the format 16:9 via the digital-to-analog converter 58.
For television systems with different numbers.of lines the figures must be changed accordingly. For a television system with 525 lines or, respectively, ~81 active lines, for example, the edge bars 21 and 22 can each contain 60 lines and the area 20 may contain 361 lines.
This improved 'letter box' method bears the following advantages:
- The picture quality of the compatible 4:3 television signal i~ better. There are no jumps and motion phase change-overs caused by changes in scanning.
.. ..
.. . , ~ , . ~. ~ . .
- 10 - ~ r; l, - The vertical resolution of the compatible receiver, especially the statical resolution, is maintained.
~ The picture in the 16:9 receiver is less sensitive to noise added in the transmission channl because the noise mostly affects only the spectral values of higher order.
- Because all DCT coefficients are transmitted in a : practically unchanged way the 16:~ receiver offers full vertical resolution.
Instead of the combination ~CT with length eight/
inverse DCT with length six, or respectively, vice versa it i8 also possible, for example, to use a combination DCT with length four/inverse DCT with length three and vice versa.
In this case, the signs of the coefficients must be inverted after every three picture dots in the vertical direction.
Instead of a DCT also other steep edge filters can be used. Spectral values which exceed, for example, 5/8 of the maximum frequency (f~x) are cut off by a low pass filter.
Spectral values in the range of 6J8 through 7/8 f~,x are separated by means of a band pass and transmitted as an additional signal. Spectral values in the range of f m ax are shifted to the area of 6/8 fmax by a suitable modulation.
In the 16:9 decoder this process is then carried out in reverse order.
The method can, with the shifting of DCT coefficlents, also be used to provide DCT coefficients for resolution enhancement in other cases of picture format changes. For example, in a doubling of the number of lines the highest coefficient from the picture with the smaller number of lines can form the highest coefficient for the inverse DCT
of doubled length for the generation of the high-definition ; ,,, . . ....................... ~ . ,.
- . . . ~ - , - .
'' :' " :; ' ' ' ' 1 ' . .
2~ J5i~.
signal and there~y effect an increase in vertical resolution in the high-definition signal.
The method can also be used for de-interlacing (conversion of a field television signal to a frame television signal). For if a frame is created from two fields each with dynamical picture contents the comb structures described in Fig-. 6 can appear.-in a disturbing ..
way. To avoid this effect it is sufficient to calculate this.disturbing content of the-total picture-, which is..
mainly represented only by the.highest vertical DCT
coefficient.,.to invert it and add it. to the existing.total.
pic.ture contents. The comb structure is thereby neutralized in an advantageous way..
.. . . . .
T l 0 ~ 0 1 :~' ; ' ~ ' ', ' `: , .. ~ ' i ' " ' . ' ' ' . ~ ' `:, , ' ~ ' '. ; ' ' - ~ ' `' `\J- ~''
H89/081P2*HA-120691 - 1 -Method, coder and decoder for transmission and for compatible reception of standardized television signals The invention concerns a method,a coder and a decoder for the transmission and for compatible reception of standardized television signals.
For the introduction of a 16:9 broad picture format into existing television standards (e.g. PAL, SECAM, NTSC) with the format 4:3 the so-called 'letter-box' method is being discussed ("Verbesserungsmoglichkeiten und Entwic~lungstendenzen bei PA~" (Possible improvements and trends for development with PAL), G. Holoch, lecture FKTG
Jan. 17, 1989 in Berlin, and "Kunftige Fernsehsysteme"
(Future television systems), F. Muller-Romer, Fernseh- und Kinotechnik, Vol. 43, issue No. 6/1989, and "Die neuen Wege de alten PAL" (New ways of the old PAL), Dr. A. Ziemer, E.
Matzel, Funkschau issue No. 18/1989). With these methods the total picture information of the 16:9 recording is represented on the 4:3 receiver in a compatible way with bars at the upper and lower edge of the picture that are not filled with visible picture contents.
This is performed in that in the studio every fourth line of the, for example, 575 active lines in the frame is taken out of a 16:9 picture with, for example, 625 lines and certain lines are tran~mitted as additional information in the bars that are hereby being left above and under the active picture. The active picture in the 4:3 receiver then comprises 431 lines and the edge bars each comprise 72 lines. This mode of presentation of, for example, movies with a 16:9 format in the 4:3 receiver has also been in use before and thus requires no adaptation on the side of the viewer.
Because the ratio of the two picture formats corresponds with the ratio of the original to the reduced REPLACEMENT SHEET
,. . , ., - , : ~ ~
.. . . . .
,, ~. ., 2~ Xl H89/081P2*HA-120691 - 2 -number of lines the geometrical distortion through the taking out (removal) of the lines is compensated.
The 16:9 receiver now evaluates the information fro~
the two edge bars in order to increase the number of active lines which has been reduced to 431 to 575 again and, thereby, to create a 16:9 picture covering the complete format.
If every one out of four lines is taken out of the 575 active lines in the fra~e, however, signals jumps are created in the 4:3 receiver which become visible in particular with diagonal or moving structures in the picture contents. In order to avoid signal jumps the lines can also be vertically interpolated in the transmitter. This, however, usually leads to a reduction in the vertical resolution in the 4:3 receiver.
In order that the picture contents of the lines in the edge bars does not appear in any disturbing way in the 4:3 receiver the amplitude of these picture contents are lowered (reduced) in the transmitter by about 13 dB and re-elevated accordingly in the 16:9 receiver. This can lead, however, to a markedly increased noise in the 16:9 receiver and, thereby, to a diminished picture quality compared with a 4:3 receiver that is today's state of the art.
In "Compatible HDTV coding for broadband ISDN", K.H.
Tzou et al., IEEE Global Telecommunications Conference &
Exhibition, Hollywood, Nov. 28, 1988, volume 2, pages 24.1.1 through 24.1.7, a method for digital coding and transmission of EQTV signals in ISDN networks is decribed in which the EQTV picture i9 extracted, with the help o~ a two-dimen~ional DCT, in reduced definition from an HDTV picture, digitally coded and transmitted in data reduced form. In an auxillary channel additional information are transmitted by means of which the HDTV picture can be reconstructed again in a high definition ISDN receiver. Hereby, picture REP~ACEMENT SHEET
'' '. ... .. ~ : ' i :: ` .
2~ .51.
H89~081P2~HA-120691 - 3 -sections of a 16:9 picture exceeding the 4:3 format are also transmitted in the auxillary channel.
Hereby, a 4:3 EQTV receiver only reproduces part of the 16:g picture contents.
It is the object of the invention to name a compatible transmission system for a 16:9 television signal using a standard television channel which supplies pictures in the letterbox format in 4:3 standard receivers and pictures in the 16:9 format in improved 16:9 receivers, in particular with a vertical resolution corresponding with the ori~inal signal and with a low noise rate.
This task is solved by the features given in claim 1.
Advantageous further developments of the invention are given in the subclaims.
First of all, at the side of the transmitter the television signal with the 575 active lines of the 16:9 picture is digitalized and in the frame specially filtered in the vertical direction. This can be performed by, for example, a DCT transformation (DCT: direct cosine transform) with the length eight.
Of the always eight coefficients generated always the first through fifth and the eighth are combined. These six coefficients are inversely DCT transformed with the length six, digital-to-analog converted and inserted at the respective position in the compressed 16:9 picture. Hereby, the 4:3 receiver has virtually the full vertical resolution.
The sixth and seventh coefficient are also digital-to-analog converted and transmitted in the bars above and below the compressed 16:9 picture.
A 4:3 receiver does not evaluate the coefficients in the two bars but presents the television picture according to the above described 'letter box' method. Because it is a characteristic effect of a DCT transformation that the signal energy is concentrated in the coefficients of lower order, the sixth and seventh coefficient usually have but small amplitudes. Through this, in a 4:3 standard receiver REPLACEMENT SHEET
the visibility of disturbing picture contents in the bars is reduced already. It is sufficient if these parts of the signal are reduced only slightly or even not at all. The advantageous result is that there is virtually no noise increase in the 16:9 receiver.
Instead of a linear reduction the amplitudes of the coefficients in the bars can be reduced using a non-linear function.and be inversely-re-elevated correspondingly in the 16:9 receiver, in order to reduce their-visibility in the 4:3 receive~ even further; Through the non-linearity of the .
reduction and elevation (greater amplitudes are reduced to a greater extent than smaller) an increase of noise in the 16:9 rec~iver .is even smaller than wlth a linear reduction and re-elevation.
An improved receiver with a picture format of 16:9 contains a decoder which evaluates the.additional information from the two edge bars and.supplies a full-format 16:9 picture. Herefore, the received television signal is digitalized, DCT-transformed with length.6 vertically in the frame; always the sixth coefficient shifted to the eighth position, the respectively corresponding sixth and seventh coefficient from the edge bars inserted at the sixth and seventh position, the so re-gained original eight DCT coefficients inversely DCT
transformed and inserted at the original positions as in the original signal. Following subsequent digital-to-analog conversion the 16:9 picture is available with full vertlcal resolution and only minimally increased noise~
Subsequently, an example embodiment of the invention is illustrated by means of the drawings. These show in:
Fig. 1 A picture in the format 16:9 ..
, .: : ,, .
- ., . .: . . . :
5~.
Fig. 2 The picture from Fig. 1 with vertically compressed active part and additional informa~ion in the two edge bars (known) Fig. 3 Representation of the active part of the picture from Fig. 2 in the 4:3 receiver (known) Fig. 4 Block circuit diagram of a 16:9 coder Fig. 5 Block circuit diagram of a 16:9 decoder Fig. 6 A dark part of the picture moving in the i horizontal direction in front of a light background Fig. 7 Average distribution of energy in the coefficients of a DCT with length eight Fig. 8 A coefflcients energy distribution in the compressed picture signal in a case of dvnamical picture contents Fig. 1 shows a television picture in the picture format 16:9 as lt is generated in a 16:9 studio, showing a circle.
Fig. 2 shows how the television picture from Fig. 1 is vertically compressed in the area 20 by a known 16:9 coder.
By way of vertical compression by the factor 4/3 431 lines are generated out of the 575 active lines in Fig. 1 as the active picture part 20 for the 4:3 receiver. This compregsion i9 performed by removing every fourth line from the picture from Fig. 1 or by means of a vertical interpolation. Through the compression the geometry of the circle has been altered. The lines removed from the part 20 of the picture or, respectively, the lines required for the U 0~1 ~t'\01 , ~ , , : , :,,: i ~ i .
'` ` ., ,, :' ` ~ , `:~ `
: - ` ' ' , ` :' "~ .
2~
decoding in the 16:9 receiver are transmitted in the two edge bars 21 and 22 as an additional signal.
In Fig. 3 it is shown that a 4:3 receiver reproduces the active part 20 of the picture from Fig. 2 in the area 30. Through the horizontal compression of the 16:9 format to the 4:3 format by the factor 4~3 the original geometry of the circle from Fig. 1 is re-established; A viewer is able to see the fUll picture contents from Fig. 1, however, the vertical resolution is reduced and there are black bars 31 and 32 at the upper and lower edges of the picture. In order that the additional signal contained in the bars does not become disturbingly visible it must be adequately reduced (lowered) in amplitude in the l6:9 coder and be present in the ultra black range (between sync level and black level).
A strong reduction of the additional signal, however, leads to a compromized signal-to-noise ratio in the 16:9 receiver due to the superimposed channel noise. This additional noise is contained in the picture signal in the local area.
In a 16:9 receiver the additional signal in the edge bars 31 and 32 is adequately amplified and formed into a picture as in Fig. 1 together with the active part 30 of the picture in connection with the horizontal 16:9 expansion.
Fig. 6 shows a dark picture part which moves in the~
horizontal direction in front of a light background.
Because in the line interlace method the fields represent different phases of motion, corresponding edges have a 'comb' structure. Now, if for example in such a comb structure every fourth line is removed, clearly visible interference patterns are created in a 4:3 receiver. In order to avoid this effect, a 'clean' presentation in the .~
:
, ,.; j, . . .
, : , . . .~
!
2~
4:3 receiver can be achieved using vertical interpolation filters. Hereby, however, higher vertical parts of the spectrum are cut off which are then unavailable for decoding in the 16:9 receiver; and this leads to a reduced vertical resolution.
From the comb structure it can be seen that for a good picture quality in the vertical direction the highest possible frequencies in the 16:9 receiver ~Eig. 6a) as well as in the compressed signal (Fig. 6b) for the 4:3 receiver must be transmitted.
( By means of a suitable vertical transformation, for example with a DCT, this requirement can be met.
In Fig. 7 the value 72 of an averaye energy content 73 of vertical transformation coefficients is shown dependent on the frequency 71. In the case of a comb structure as in Fig. 6a the highest parts 74 of the spectrum are of mar~edly increased values because the base pattern of the eighth coefficient also has a like structure.
In a DCT of the length eight the part 74 of the spectrum is represented by the eighth coefficient. Through ; a compression by the factor 4/3 the value eight becomes the value six. If the sixth and seventh coefficients are removed from the eight DCT coefficients and the eighth is inserted at the position of the sixth, a comb structure as in Fig. 6b is generated through inverse transformation. A
DCT with the length eight becomes a DCT with the length 9iX.
In Fig. 8 the corresponding spectrum of such a DCT of the length six is shown. Always the sixth and seventh coefficients are transmitted as an additional signal in the bars 21 and 22. In an advantageous way their values are compressed in an non-linear way and inversely expanded - ~ . ~, , ~ - . :
- 8 ~
accordingly in the 16:9 receiver in order to achieve an improved signal-to-noise ratio.
The 4:3 receiver does not evaluate these additional signals. Because, as shown in Fig. 7, the statistic average of the values of the DCT coefficients of higher order are significantly smaller than those of lower order a reduction of their leve~s for the purpose of~avoiding the visibility in the 4:3 receiver is not - or only to a small extent -required.
In an advantageous way the coefficients in the edge bars do not represent picture signals in the local area - as it is the case in the known method - but spectral values of higher frequencies which appear to the viewer as a high frequent noise. Such a noise will naturally be perceived by the viewer as less disturbing than a distortedly presented additional picture content.
Fig. 4 shows the block digram of a 16:9 coder. The television signals in the format 16:9 coming from, for example, a camera are analog-to-digital converted 41 and written into a memory 42. From the memory 42 the scanning values of always eight picture dots lying vertically above each other are continuously read out and DCT transformed in circuit 43. The sixth and seventh DCT coeffiecients are sorted out in circuit 44 and compressed in a non-linear way in circuit 46. This can be performed, for example, by means of the function y = xl/~ (y = x to the power of 1/3) whereby x stands for the input signal and y for the output signal.
The first through fifth and the eighth DCT coefficients are always combined in circuit 44 and inversely DCT transformed with the length six in the circuit 45. The output signals of the circuit 45 and 46 are written into the memory 47 and output as an analog, compatible television signal in the 4:3 format via the digital-to-analog converter 48.
- ,, .:, ~. ,, :.: . -, ' ' ' , : ~ .;, ~, , , ~
2r~
Fig. 5 shows the ~lock diagram o~ a corresponding 16:9 decoder in the 16:9 receiver. ~he signals in the 4:3 format are first converted analog-to-digital in the circuit 51 and written into the memory 52. From here the scanning values of.always six piture dots lying one above the other are read out and DCT transformed with the length six.in circuit 53.
The respective corresponding sixth and seventh-coefficients are fed..from the memory 52 into-the circuit 54 and expanded inversely with respect:to t~e function of the circuit g6,..
i.e. using y = X3 (y = X to the power of 3), in a non-linear way.. In circuit 55 the sixth of the DCT trans~ormed.
.coefficients.is inserted at the position of the originally eighth and the sixth and seventh coe~ficients from-circuit 54 are shifted to the sixth and seventh position. The original eight DCT coe~ficients that.are~re-gained in ~his.
way are inversely DCT transformed in circuit 56 and written into the memory 57. From there they are output as an analog television signal in the format 16:9 via the digital-to-analog converter 58.
For television systems with different numbers.of lines the figures must be changed accordingly. For a television system with 525 lines or, respectively, ~81 active lines, for example, the edge bars 21 and 22 can each contain 60 lines and the area 20 may contain 361 lines.
This improved 'letter box' method bears the following advantages:
- The picture quality of the compatible 4:3 television signal i~ better. There are no jumps and motion phase change-overs caused by changes in scanning.
.. ..
.. . , ~ , . ~. ~ . .
- 10 - ~ r; l, - The vertical resolution of the compatible receiver, especially the statical resolution, is maintained.
~ The picture in the 16:9 receiver is less sensitive to noise added in the transmission channl because the noise mostly affects only the spectral values of higher order.
- Because all DCT coefficients are transmitted in a : practically unchanged way the 16:~ receiver offers full vertical resolution.
Instead of the combination ~CT with length eight/
inverse DCT with length six, or respectively, vice versa it i8 also possible, for example, to use a combination DCT with length four/inverse DCT with length three and vice versa.
In this case, the signs of the coefficients must be inverted after every three picture dots in the vertical direction.
Instead of a DCT also other steep edge filters can be used. Spectral values which exceed, for example, 5/8 of the maximum frequency (f~x) are cut off by a low pass filter.
Spectral values in the range of 6J8 through 7/8 f~,x are separated by means of a band pass and transmitted as an additional signal. Spectral values in the range of f m ax are shifted to the area of 6/8 fmax by a suitable modulation.
In the 16:9 decoder this process is then carried out in reverse order.
The method can, with the shifting of DCT coefficlents, also be used to provide DCT coefficients for resolution enhancement in other cases of picture format changes. For example, in a doubling of the number of lines the highest coefficient from the picture with the smaller number of lines can form the highest coefficient for the inverse DCT
of doubled length for the generation of the high-definition ; ,,, . . ....................... ~ . ,.
- . . . ~ - , - .
'' :' " :; ' ' ' ' 1 ' . .
2~ J5i~.
signal and there~y effect an increase in vertical resolution in the high-definition signal.
The method can also be used for de-interlacing (conversion of a field television signal to a frame television signal). For if a frame is created from two fields each with dynamical picture contents the comb structures described in Fig-. 6 can appear.-in a disturbing ..
way. To avoid this effect it is sufficient to calculate this.disturbing content of the-total picture-, which is..
mainly represented only by the.highest vertical DCT
coefficient.,.to invert it and add it. to the existing.total.
pic.ture contents. The comb structure is thereby neutralized in an advantageous way..
.. . . . .
T l 0 ~ 0 1 :~' ; ' ~ ' ', ' `: , .. ~ ' i ' " ' . ' ' ' . ~ ' `:, , ' ~ ' '. ; ' ' - ~ ' `' `\J- ~''
Claims (9)
1. Method for the transmission and and compatible reception of standardized television signals with a first picture format, particularly 4:3, in which the main picture contents are located in a second picture format with a larger picture aspect ratio, particularly 16:9, within the first and with additional information (31, 32) which is located in the area of the first picture format outside the main picture contents (30) and which can be decoded by a receiver for the second picture format to present, together with the information from the main picture contents, a full-format picture in the second picture format in this receiver, whereby the transmitted television signals can be decoded by a standard receiver for the first picture format without evaluation of the additional information, c h a r a c t e r i z e d i n t h a t, on the coder side:
- the television signal in the first picture format is generated from a source signal of the second picture format in that vertical signal partitions of picture elements lying above each other are generated and the values of these picture elements are transformed always by means of a first one-dimensional transformation mode into spectral components;
- within these signal partitions high-frequent spectral components (74) are shifted to a position (84) of less high-frequent spectral components and other, less high-frequent spectral components are removed from the total spectrum of the respective signal partition;
- from these, less high-frequent spectral components the additional information is generated;
- from the spectral components not displaced (83) together with the high-frequent spectral components H89/081P2*HA-120691 - ? -corresponding picture element values for the main picture contents are regenerated by means of an inverse, second one-dimensional transformation, and that with the decoding for the second picture format:
- these picture element values are transformed into spectral components using the second transformation mode;
- these spectral components together with the respective associated high-frequent spectral components from the additional information are shifted back again to the original arrangement in the signal partitions on the coder side;
- these total spectral components are transformed always using the inverse first transformation mode into picture element values, and that with the decoding for the first picture format:
only the transmitted picture element values from the main picture contents are used.
- the television signal in the first picture format is generated from a source signal of the second picture format in that vertical signal partitions of picture elements lying above each other are generated and the values of these picture elements are transformed always by means of a first one-dimensional transformation mode into spectral components;
- within these signal partitions high-frequent spectral components (74) are shifted to a position (84) of less high-frequent spectral components and other, less high-frequent spectral components are removed from the total spectrum of the respective signal partition;
- from these, less high-frequent spectral components the additional information is generated;
- from the spectral components not displaced (83) together with the high-frequent spectral components H89/081P2*HA-120691 - ? -corresponding picture element values for the main picture contents are regenerated by means of an inverse, second one-dimensional transformation, and that with the decoding for the second picture format:
- these picture element values are transformed into spectral components using the second transformation mode;
- these spectral components together with the respective associated high-frequent spectral components from the additional information are shifted back again to the original arrangement in the signal partitions on the coder side;
- these total spectral components are transformed always using the inverse first transformation mode into picture element values, and that with the decoding for the first picture format:
only the transmitted picture element values from the main picture contents are used.
2. Method according to claim 1, c h a r a c t e r -i z e d i n t h a t the first transformation mode is a DCT with a first length, and the second transformation mode is a DCT with a second, smaller length whereby, in particular, the ratio of the two DCT
lengths corresponds to the ratio of the two picture formats.
lengths corresponds to the ratio of the two picture formats.
3. Method according to claim 2, c h a r a c t e r -i z e d i n t h a t instead of a DCT filter (low pass, high pass, band pass filter) with the respective spectral ranges corresponding limit frequencies are used.
4. Method according to one or more of the claims 1 H89/081P2*HA-120691 - ? -through 3, c h a r a c t e r i z e d i n t h a t the signal partitions with the first transformation and with the inverse first transformation always contain four or eight picture element values or, respectively, transformation coefficients.
5. Method according to claim 4, c h a r a c t e r -i z e d i n t h a t always in the signal partitions either the high-frequent spectral components (74) consist of the eighth and the less high-frequent spectral components of the sixth and seventh transformation coefficient or the high-frequent spectral components consist of the fourth and the less high-frequent spectral components of the third transformation coefficient.
6. System according to one or more of claims 1 through 5, c h a r a c t e r i z e d i n t h a t the additional information (31, 32) prior to the transmission is reduced (lowered) in amplitude, in particular in accordance with a non-linear function, and is inversely re-elevated accordingly with the decoding for the second picture format.
7. Coder for a method according to one or more of the claims 1 through 6, to which at the input of an analog-to-digital converter (41) a source signal of the second picture format is fed and which is provided with a downstream first memory (42), with a downstream one-dimensional DCT transformer for the first transformation mode (43), with a downstream sorter (44) which fowards less high-frequent coefficients to a weighting circuit (46) with a non-linear function and the other coefficients in combined form to an inverse one-dimensional DCT transformer for the second transformation mode (45), with a second memory (47) H89/081P2*HA-120691 - ? -into which the output signals of the inverse DCT
transformer and the weighting circuit are written accordingly and which is topped (followed) by a digital-to-analog converter (48), which supplies pictures in the first picture format as its output signal.
transformer and the weighting circuit are written accordingly and which is topped (followed) by a digital-to-analog converter (48), which supplies pictures in the first picture format as its output signal.
8. Decoder for a method according to one or more of claims 1 through 6 to which a source signal in the first picture format is fed at the input of an analog-to-digital converter (51) and which is provided with a downstream first memory (52) with a downstream one-dimensional DCT transformer (53) and with a downstream weighting circuit (54) with a non-linear function that is inverse with respect to the weighting circuit on the coder side (46), with a downstream sorter (55) which combines less high-frequent coefficients from the weighting circuit and the other coefficients from the DCT transformer in accordance with the original arrangement on the coder side and feeds them to an inverse one-dimensional DCT transformer (56), with a downstream second memory (57) which is followed by a digital-to-analog converter (58) which supplies pictures in the second picture format as its output signal.
9. Method for the conversion of standardized television signals with fields to television signals with frames by means of combining always two associated fields to one frame, c h a r a c t e r i z e d i n t h a t in the frames resulting therefrom always the highest-frequent coefficient (74) of a one-dimensional DCT of a predetermined length is calculated within vertical signal partitions representing dynamical picture contents of said length, in particular of eight picture element scanning values, that this coefficient H89/081P2*HA-120691 - ? -is inversely DCT transformed with this length and the so resulting contents of the signal partitions are added to the frames in inverted form.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3929967.8 | 1989-09-08 | ||
| DE3929967A DE3929967A1 (en) | 1989-09-08 | 1989-09-08 | TELEVISION TRANSMISSION SYSTEM |
| PCT/EP1990/001468 WO1991003906A1 (en) | 1989-09-08 | 1990-09-01 | Tv transmission system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2065851A1 true CA2065851A1 (en) | 1991-03-09 |
Family
ID=6388968
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002065851A Abandoned CA2065851A1 (en) | 1989-09-08 | 1990-09-01 | Tv transmission system |
Country Status (16)
| Country | Link |
|---|---|
| US (1) | US5274449A (en) |
| EP (1) | EP0490983B1 (en) |
| JP (1) | JPH05500743A (en) |
| CN (1) | CN1029284C (en) |
| AT (1) | ATE116503T1 (en) |
| AU (1) | AU6422590A (en) |
| CA (1) | CA2065851A1 (en) |
| DD (1) | DD295482A5 (en) |
| DE (2) | DE3929967A1 (en) |
| FI (1) | FI921001A0 (en) |
| HK (1) | HK114396A (en) |
| HU (1) | HUT63528A (en) |
| MY (1) | MY107401A (en) |
| TR (1) | TR24692A (en) |
| WO (1) | WO1991003906A1 (en) |
| ZA (1) | ZA907061B (en) |
Families Citing this family (18)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0581808B1 (en) * | 1991-04-25 | 1997-12-10 | Deutsche Thomson-Brandt Gmbh | Process for compatible transmission, decoding or recording of progressively scanned picture signals in interlace format |
| DE4117994A1 (en) * | 1991-06-01 | 1992-12-03 | Thomson Brandt Gmbh | METHOD, CODER AND DECODER FOR COMPATIBLE TRANSMISSION AND / OR RECORDING AND FOR RECEIVING AND / OR PLAYING BACK TELEVISION SIGNALS |
| GB9123004D0 (en) * | 1991-10-30 | 1991-12-18 | British Broadcasting Corp | Improvements in television systems |
| JP2759727B2 (en) * | 1992-04-22 | 1998-05-28 | 日本ビクター株式会社 | Display device |
| JP3302091B2 (en) * | 1993-03-31 | 2002-07-15 | キヤノン株式会社 | Encoding device and encoding method |
| KR960036638A (en) * | 1995-03-31 | 1996-10-28 | 김광호 | Vertical stretching apparatus and method of image in TV apparatus |
| EP0785682A4 (en) * | 1995-07-19 | 1998-10-14 | Toshiba Kk | Letter box converter |
| KR100487203B1 (en) * | 1997-10-17 | 2005-08-17 | 삼성전자주식회사 | Display method of video display device |
| US7505531B1 (en) | 2000-03-17 | 2009-03-17 | Bridgewave Communications, Inc. | Signal communications system and method for noisy links |
| US7190847B2 (en) * | 2002-02-12 | 2007-03-13 | International Business Machines Corporation | Method, system, and program for fractionally shifting data subject to a previous transformation |
| US7079192B1 (en) * | 2002-07-30 | 2006-07-18 | The Regents Of The University Of California | Letter box line blackener for the HDTV/conventional-analog hybrid system |
| US20060059514A1 (en) * | 2004-09-10 | 2006-03-16 | Eric Hsiao | Method and apparatus for utilizing blank space on a high definition television screen |
| US8731007B2 (en) * | 2005-12-30 | 2014-05-20 | Remec Broadband Wireless, Llc | Digital microwave radio link with a variety of ports |
| US8711888B2 (en) * | 2005-12-30 | 2014-04-29 | Remec Broadband Wireless Llc | Digital microwave radio link with adaptive data rate |
| EP1962513A1 (en) * | 2007-02-26 | 2008-08-27 | Vestel Elektronik Sanayi ve Ticaret A.S. | Methods and apparatus for processing of a digital image |
| US20100007788A1 (en) * | 2008-07-09 | 2010-01-14 | Vizio, Inc. | Method and apparatus for managing non-used areas of a digital video display when video of other aspect ratios are being displayed |
| US8743180B2 (en) * | 2011-06-28 | 2014-06-03 | Cyberlink Corp. | Systems and methods for generating a depth map and converting two-dimensional data to stereoscopic data |
| CN115049658B (en) * | 2022-08-15 | 2022-12-16 | 合肥的卢深视科技有限公司 | RGB-D camera quality detection method, electronic device and storage medium |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3414452C1 (en) * | 1984-04-17 | 1985-10-10 | Robert Bosch Gmbh, 7000 Stuttgart | Method for compatibly transmitting a colour television signal containing additional information |
| US4984078A (en) * | 1988-09-02 | 1991-01-08 | North American Philips Corporation | Single channel NTSC compatible EDTV system |
| JPH0817484B2 (en) * | 1988-10-22 | 1996-02-21 | 日本テレビ放送網株式会社 | Television signal broadcasting device and same signal receiving device |
| DE3840054C1 (en) * | 1988-11-28 | 1989-09-07 | Institut Fuer Rundfunktechnik Gmbh, 8000 Muenchen, De | |
| US5128758A (en) * | 1989-06-02 | 1992-07-07 | North American Philips Corporation | Method and apparatus for digitally processing a high definition television augmentation signal |
| US5097332A (en) * | 1990-05-02 | 1992-03-17 | Faroudja Y C | Processing method for wide-aspect-ratio television signal for standards-compatible transmission and display |
-
1989
- 1989-09-08 DE DE3929967A patent/DE3929967A1/en not_active Withdrawn
-
1990
- 1990-08-04 CN CN90106656A patent/CN1029284C/en not_active Expired - Fee Related
- 1990-09-01 JP JP2513246A patent/JPH05500743A/en active Pending
- 1990-09-01 HU HU92697Q patent/HUT63528A/en unknown
- 1990-09-01 CA CA002065851A patent/CA2065851A1/en not_active Abandoned
- 1990-09-01 WO PCT/EP1990/001468 patent/WO1991003906A1/en active IP Right Grant
- 1990-09-01 AU AU64225/90A patent/AU6422590A/en not_active Abandoned
- 1990-09-01 DE DE59008153T patent/DE59008153D1/en not_active Expired - Fee Related
- 1990-09-01 AT AT90914152T patent/ATE116503T1/en not_active IP Right Cessation
- 1990-09-01 EP EP90914152A patent/EP0490983B1/en not_active Expired - Lifetime
- 1990-09-05 ZA ZA907061A patent/ZA907061B/en unknown
- 1990-09-07 MY MYPI90001541A patent/MY107401A/en unknown
- 1990-09-07 DD DD90343895A patent/DD295482A5/en not_active IP Right Cessation
- 1990-09-19 TR TR90/0804A patent/TR24692A/en unknown
-
1992
- 1992-03-06 FI FI921001A patent/FI921001A0/en unknown
- 1992-04-10 US US07/890,638 patent/US5274449A/en not_active Expired - Fee Related
-
1996
- 1996-06-27 HK HK114396A patent/HK114396A/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| HUT63528A (en) | 1993-08-30 |
| CN1050118A (en) | 1991-03-20 |
| HU9200697D0 (en) | 1992-08-28 |
| ATE116503T1 (en) | 1995-01-15 |
| AU6422590A (en) | 1991-04-08 |
| TR24692A (en) | 1992-03-01 |
| DE59008153D1 (en) | 1995-02-09 |
| US5274449A (en) | 1993-12-28 |
| EP0490983B1 (en) | 1994-12-28 |
| WO1991003906A1 (en) | 1991-03-21 |
| DD295482A5 (en) | 1991-10-31 |
| MY107401A (en) | 1995-11-30 |
| JPH05500743A (en) | 1993-02-12 |
| CN1029284C (en) | 1995-07-05 |
| EP0490983A1 (en) | 1992-06-24 |
| ZA907061B (en) | 1991-06-26 |
| FI921001A0 (en) | 1992-03-06 |
| DE3929967A1 (en) | 1991-03-14 |
| HK114396A (en) | 1996-07-05 |
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| FZDE | Discontinued |
Effective date: 19940301 |