FR2541544A1 - TELEVISION CIRCUIT FOR REDUCING PAPILLOTE AT REPRODUCTION - Google Patents

Abstract

TELEVISION CIRCUIT FOR REDUCING REPRODUCTION FLIP FOR A PS1 IMAGE SIGNAL CONTAINING IMAGE INFORMATION REPEATING IN CYCLES OF TWO SUCCESSIVE AND VARIABLE FRAME PERIODS, POSSIBLE STEP BY STEP BETWEEN THESE CYCLES. SIGNAL SOURCES 1, SUCH AS FOR EXAMPLE FILM-TELEVISION CONVERTERS AND FIELD SKIP SIGNAL STORAGE AND REPRODUCTION DEVICES PROVIDE SUCH A SIGNAL. THE CIRCUIT IS EQUIPPED WITH A SIGNAL COMBINATOR CIRCUIT 6 WHICH IS COUPLED, ON THE ONE HAND VIA A DELAY DEVICE 4 AND ON THE OTHER HAND DIRECTLY, TO A SIGNAL INPUT TERMINAL 2, FROM A SWITCHING CIRCUIT 11, THE INPUT TERMINAL 2 AND THE OUTPUT OF THE COMBINATOR CIRCUIT 6 BEING CONNECTED TO A SIGNAL OUTPUT TERMINAL 3. THAT DURING SECOND FOLLOWING FRAME PERIODS, INPUT TERMINAL 2 ARE RESPECTIVELY COUPLED TO OUTPUT TERMINAL 3, A COMBINED IMAGE SIGNAL PS 2 IS OBTAINED WITH REDUCTION OF FLIP AT REPRODUCTION. APPLICATION: REPRODUCTION OF TELEVISION IMAGES.

Description

"Television circuit for flicker reduction

to reproduction ".

  The present invention relates to a television circuit for reducing flicker at the

  reproduction, in the case of an image signal comprising

  image information repeating itself in cycles of two successive frame periods and possibly varying step by step between these cycles, this circuit being

  provided, between an input terminal and an output terminal

  of a delay device coupled to the

  and having a delay equal to at least one frame period, of a signal combining circuit

  coupled with the input terminal and an output of the

  delay signal and a switching circuit coupled to an output of the signal combiner circuit and the output terminal, to form together combined image signals having image information in frame periods derived from various frame periods. Such a television circuit is described in US Pat. No. 3,886,589, in the case of the use of a "signal skip" signal storage and reproduction device. signals are generated, the combined image signals are formed using the delay device and the signal combining circuit; the image signals are then alternately stored and not stored (field skip) via the switching circuit The storage of signals can

  take place during one frame period out of two.

  When reproducing the signal stored by the

  signal stored and reproduced, the stored information is then repeated once in the next frame period.

  television image signal comprising information

  image repeating itself in cycles of two

  successive wefts and possibly varying step by step between these cycles The formation of the signals

  images before storage allows, in accordance with

  the aforementioned patent, to obtain a reduction of flicker phenomena on reproduction on a reproducing device of said image signal

varying step by step.

  In addition, as described in said patent, a

  stepwise image signal can be the result of

  state of a film-television conversion In this case, the information belonging to an image fails in a frame period of the image signal, but repeatedly arrives in the frame period

  If, as a result of this, we selectively use

  the intermittent storage described of combined image signals, the storage and reproduction device will provide, for the reproduction of the signals,

  a suitable image signal varying stepwise.

  Despite the fact that in both cases, we obtain a certain reduction of the flicker in

  forming the image signal varying step by step

  on a screen, prior to signal storage, by means of the combined image signals over a larger number of frame periods, the stepwise variation resulting from the repetition of the information in the cycle continues to cause flickering None

  measure is presented in the said patent in order to

dier to this defect.

  The object of the invention is to provide a

  cooked television for a reduction of the papillo-

  to reproduction in the case of a signal

  image having image information is repeated

  in cycles of two successive frame periods

  sive and possibly varying stepwise between these cycles, this image signal being able to come, as

  example, directly from a film-to-movie converter

  television or a storage and repro-

  the production of "field skip" signals, whether or not

  described combination of signals before storage.

  For this purpose, a television circuit conforming to the

  vention is characterized in that said signal -

  image containing image information is repeated

  in cycles of two successive frame periods

  sive and possibly varying stepwise between these cycles is applied to the input terminal of the circuit of

  television, this input terminal can be connected to

  via the switching circuit at the output terminal of the television circuit, so that, via the switching circuit,

  the output of the signal combining circuit and the

  of the television circuit are coupled to each other during first frame periods of two frame period cycles, and the input terminal and the output terminal are coupled to one another during second frame periods which

  follow the first ones in the cycles of two

weft.

  The invention will be described hereinafter in more detail, by way of example, with reference to the drawings

annexed in which: -

  FIG. 1 is a block diagram of a circuit

  television television according to the invention, and FIG. 2 comprises some diagrams of

  time illustrating the operation of the circuit

shown in Fig 1.

  In the television circuit shown in FIG. 1 denotes a signal source La

  signal source 1 produces two signals PSO and P 51.

  The signal P 51 is a television image signal or

  video signal consisting of lines and frames, the information

  The picture signal is combined with line and frame synchronization information present in blanking periods. For synchronization information present or not, it is to be understood that the signal P 51 comprises an image signal comprising image information repeating itself according to cycles of

  two successive and varying frame periods (possibly

  In order to provide such a signal P 51, the signal source 1 may, for example, be provided with a storage device and

  for the reproduction of "field skip" signals or a

  In the following description, we consider

  example, more film-to-television conversion

  Fig 2 shows some diagrams

  time as a function of time t which serve to illustrate the operation of the circuit shown on the

  Fig 1 In Fig 2, the letter M designates a di-

  gram duration of a succession of film image information, some of which are indicated by

  Mn-1 #Mn and Mn + 1 In the case of film-to-television conversion

Mn-1 ln Mn + 1.

  can be performed in a known manner with a continuous or intermittent transport of the film and in association or not with a flash device, the information belonging to a film image does not fall in a period of television frame , but is repeated in the next frame period, these first and second frame periods

  being designated by TV 1 and TV 2 on Fig 2

  The time diagrams belonging to the signals PSO and P 51 are indicated in relation to the time diagram M in FIG.

  with a period of recurrence or repetition

  equal to two periods of time (2 TVs) and has a symmetrical crenellated shape between two design levels T 1 and T 2. An adequate diagram of the signal P 51 according to the time is shown in FIG.

  Mn film cited as an example leads to an infor-

  TV picture image Pn in a first frame period T Vl and to a picture information

  Repeated Pl in a second TV frame period 2.

  In the same way, the previous and next film image information Mn and M resulting in n + 1: television picture information Pnl 'Pn' and Pn + 1 Pn + 1 In the case where, for the In the case of television-to-television conversion, a simple 2: 1 interleaved television system is used, as established, for example, in a television standard, two successive TV frame periods form an image period. of television lines correspond to the image information Pn l 1 5 p p Pn Pn + 1 and Pn-1 Pn 'Pn + 1 The time diagram of the signal P Sl shows that the image information appears in

  cycles (T Vl, TV 2) of two successive frame periods

  T Vl and TV 2 When no interleaving is -

  used, the image information P and the informa-

  Repeated picture frames P 'which follow are identical in the cycles (TV 1, TV 2) When interleaving is used, the picture information P and P' are not identical but, for the same picture information of movie M, a shift of a television line

  produced in the sense of frame analysis Modifications

  fications between the M movie image information

  appear step by step after the film conversion-

  television between cycles (T Vl, TV 2) of information

  P and P 'and in particular between the repeated image information P' of the previous cycle and the information

  image of the clean cycle These changes in information

  step by step often appear in the form of abrupt changes, mainly as a result of

  cinematographic montage of scenes taken separately

  254 Â 544 b ry Without further measurement, reproduction on a screen

  signal P 51, varying stepwise (abruptly)

  flicker phenomena with a view to ob-

  to reduce flicker to reproduc-

  In a first embodiment, signal P 51 is applied to a signal input terminal 2 of a television circuit according to the invention shown in Fig. 1 which then provides a signal output terminal 3 with a signal output terminal.

  signal P 52 more suitable for reproduction.

  Fig. 2 illustrates a diagram of the time-dependent signal P 52 derived from the signal P 51 and having delayed image information P "as a combined image signal in addition to the image information P

  and repeated image information P '

  delayed picture frames P "can be derived from

  the repeated picture information P 'immediately preceding

  dente or image information P as it is the

  preferably in interleaving systems.

  In the foregoing description, it is necessary to

  that signal source 1 has a converter

  As will be apparent from the

  the following description, it is also possible that the conversion

  film-television transmission occurs elsewhere and that a resultant stepless television picture signal is received and applied to an input terminal 1 i of the signal source 1 for the supply of the signals

P 51 and PSO.

  In the circuit shown in FIG.

  input terminal 2 is connected to an input of a

  The device 4 has a delay which is equal to at least one TV frame period. In the case where the signal P 51 belongs to a 2: 1 interleaved television system, it is advantageous, in order to obtain an improvement of the image quality to the reproduction of the combined image signal P 52, to use a delay of an image period of 2 TV An output of the delay device 4 is connected to an input of 5 a signal combining circuit 6 of which another input 7 is connected to the input terminal 2 In the circuit 6, inputs of an adder circuit 8 are connected to the inputs 5 and 7, a divide by two circuit 9 following the adder circuit 8 An output of the signal combining circuit 6 connected to the output of the divide-by-two circuit 9 is connected to an input 10 of a circuit

  11 An input 12 of the communication circuit

  11 is connected to the input terminal 2.

  Cooking switch 11 is shown in FIG.

  as a mechanical switch with two

  switching points Tl and T 2 which are connected, res-

  respectively at signal inputs 10 and 12, but

  in practice it is an electronic switch

  In this case, the switching circuit is

  provided with a switching signal input 13.

  The input 13 is connected to an input terminal 14 of the

  television circuit shown in FIG.

  13 receives the PSO signal as a switching signal The switching circuit 11 has an output carrying the signal P 52 which is connected to the output terminal 3 In the switching circuit

  11, the output terminal 3 is connected, alternatively

  the switching contacts T1 and T2 under the control of the switching signal PSO having the signal levels indicated by the same references.

  T1 and T2 The communication established by the contact of.

  T 2 or Tl is indicated, in the case of cir-

  bake switching 11, respectively by a solid line and a line in chainlines, these lines corresponding to arrowed lines of the same configuration T 2 and Tl in Fig 2 between the time diagrams P Sl and P 52 The lines indicated in FIG. 2 between the time diagrams P 51 and P 52 serve to illustrate the information transfers, the chain-line line T 1 corresponding either to a dashed line T 1 or to a dotted line T 1 As as shown in FIGS. 2 and 1, the dashed line T 1 corresponds to a

  delay equal to one TV frame period for the

  delay 4, whereas when this delay is

  equal to 2 TV, it corresponds to the dotted line T 1.

  It appears from Fig 2 and Fig 1 that

  the input terminal 2 and the output terminal 3 are

  to one another during TV frame periods 2 Repeated image information, for example,

  Pn 1, Pin, Pn + 1 are thus transmitted without modification.

  During the TV 1 frame periods, the terminal

  output 3 is connected to the output of the com-

  signals, 6 with which half of the information

  momentary image images Pn-1 Pn Pn + 1 is trans-

  via the input 7 and half of the delayed image information P-2 PP 'n-2 1 Pn-11' n is transmitted via the input 5. that an image information sequence P Pn 'P, taken as an example, is n n + 1 converted to a sequence (P * + P) Pl n N n

  (P "+ Pn + l) A sudden change in the information

  image mation between Pn 'and Pn + 1 is attenuated by Pn; and (N P n + a Pn Set 2 (Pn "+ Pn + 1) which, during a reproduction

  on a screen, results in a reduction of the flicker.

  In FIG. 2, three arrows 15 underline, in the case of the time chart P 52, the manner in which each image information is distributed over time over three periods.

  successive TV frame periods, during a reproduction

  on a screen, in order to obtain a reduction

flicker.

  To reduce flicker, it is essential to

  that, during the first TV 1 frame periods of the TVI, TV 2 frame periods, the circuit

  signal combiner 6 is coupled to the output terminal

  3 and that, during the second TV 2 frame periods, the input terminal 2 is coupled to the terminal of

  output 3 If the coupling was different, we get

  Instead of the desired sequence or NN (Pn + Pn + 1), a sequence n-2 ni) n Ah (P "'+ Pl) should be used when using a delay device 4 having a delay of 2 TV (interlace system) or a sequence

  P'1 P, P for a TV delay In this case, the

n-i Pn Pn

  P "'is the repeated image information

  which is delayed by the TV picture period.

  In the first case, the abrupt variation of information

  mation remains present between the first and the second image information in the order and, in the second case, compared to the time diagram P 51, the sequence for the time diagram P 52 is unchanged In both cases, the reduction desired flicker

  to reproduction is not obtained.

  In the circuit shown in FIG.

  the signal source 1 provides the switching circuit

  11, the PSO switching signal with the phase

  correct, the signal levels Tl and T 2 of the di-

  PSO time gram of FIG. 2 corresponding to frame period cycles (TV 1, TV 2) The time diagrams M, PSO and PSI of FIG.

  to each other with the correct phase, through

  1 of the signal source 1 of FIG. 1 in which the film-television conversion takes place in the manner provided. Another possibility lies in the fact that the film-television conversion does not occur in the signal source 1 itself, but in another place which precedes it, so that an image signal

  thus varying step by step is applied to the terminal of

  1 i of the signal source 1 and is transmitted, for example, without modification as a signal P 51. In order to obtain the PSO switching signal with the correct phase, it is now necessary to extract the received signal (P 51) from it. even information concerning the cycle of frame periods (TV 1, TV 2) For the realization of a circuit intended to indicate the image information of the sequence of TV frame periods that correspond to each other, it is possible to refer to the Applicant's Dutch patent application No. 83 00592 filed on the same day as the present memory. When such a circuit is present in the signal source 1, a stepwise varying image signal received from elsewhere may be applied to the input terminal 1 of the signal source 1 to provide

the PSO and P Sl signals.

  The presence of the delay device 4 of FIG. 1 makes it possible to obtain a combined image signal

  P 52 at the exit terminal 3, in which an informa-

  determined image, its repetition and information

  delayed picture formation appear combined over three TV frame periods by means of a delay device by means of which the signal P 51 can be delayed by

  several periods of frame or image, we can

  sea a combination of signals over these periods.

R EV E N D I C A T I O N

  A television circuit for reducing flicker on reproduction, in the case of an image signal comprising image information repeating itself in cycles of two successive frame periods and optionally varying stepwise between these cycles, this circuit being provided, between an input terminal and an output terminal, of a delay device coupled to the input terminal and having a delay equal to at least one frame period, a

  signal combining circuit coupled to the input terminal

  and one output of the delay device and a switching circuit coupled to an output of the signal combiner circuit and the output terminal, for

  to form combined image signals together

  both frame-time image information from various frame periods, characterized

  in that said image signal containing information

  image repetition in cycles of two.

  periods of frame-successive and possibly varying-

  step by step between these cycles is applied to the

  no entry (2) of the television circuit, this borned-

  tream (2) connectable via the switching circuit (11) to the output terminal (3) of the

  television circuit, so that, through

  switching circuit (11), the output of the cir-

  signal combiner (6) and the television circuit (3) are coupled to each other during

  first frame periods of the cycles of two

  weft and the input terminal (2) as well as the output terminal (3) are coupled to each other during

  second frame periods following the first

  in the cycles of two frame periods.