System for recording and reproducing a wide bandwidth video signal via a narrow bandwidth medium

• US 6,134,373 A
• Filed: 11/04/1991
• Issued: 10/17/2000
• Est. Priority Date: 08/17/1990
• Status: Expired due to Fees

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Yun, Jong Kyung, Schnitzler, Raymond, Ko, Jung Wan, Strolle, Christopher H., Patel, Chandrakant B., Wedam, Werner F.
• Primary Examiner(s): TRAN, THAI Q
• Application Number:
  US07/787,690
• Time in Patent Office: 3,270 Days
• Field of Search: 358/310, 358/335, 358/330, 358/11, 358/21 R, 358/12, 358/13, 358/133, 358/105, 358/135, 358/141, 358/142, 358/146, 358/16, 358/31, 358/8, 360/33.1
• US Class Current: 386/304
• CPC Class Codes: H04N 9/797 for recording the signal in a plurality of channels, the bandwidth of each channel being less than the bandwidth of the signal H04N9/804, H04N9/81, H04N9/82 take precedence
• CPC Class Codes: H04N 9/7976 by spectrum folding of the high frequency components of the luminance signal
• CPC Class Codes: H04N 9/80 Transformation of the television signal for recording, e.g. modulation, frequency changing; Inverse transformation for playback
• CPC Class Codes: H04N 9/8205 involving the multiplexing of an additional signal and the colour video signal
• CPC Class Codes: H04N 9/831 using intermediate digital signal processing
• CPC Class Codes: H04N 9/835 involving processing of the sound signal
• CPC Class Codes: H04N 9/84 the recorded signal showing a feature, which is different in adjacent track parts, e.g. different phase or frequency
• CPC Class Codes: H04N 9/898 using frequency multiplication of the reproduced colour signal carrier with another auxiliary reproduced signal, e.g. a pilot signal carrier H04N9/83 takes precedence

Abstract

An encoder separates luminance and chrominance signal components of a composite video signal. The frame-to-frame changes in the luminance signal are detected, and a motion signal is derived therefrom. The higher frequency portion of the luminance signal is adaptively de-emphasized in amplitude and folded into the spectrum of the lower frequency portion of the luminance signal, to generate a folded-spectrum luminance signal for modulating the frequency of a luma carrier. In a combined signal, suitable for magnetic recording in accordance with a modified VHS standard, the chrominance signal is translated in frequency to generate a color-under signal in a frequency band below that occupied by the FM luma carrier. The de-emphasized higher frequency portion of the luminance signal, as folded into its lower frequency portion, and encoding of the motion signal onto vacant portions of the frequency band below that occupied by the FM luma carrier in such a magnetic recording facilitate its being compatibly reproduced by conventional VHS reproduction devices. In a wideband reproduction device a decoder demodulates the folded-spectrum luminance signal from the FM luma carrier, unfolds the lumininance signal, and reemphasizes the high frequencies of the unfolded luminance signal. The color-under signal is translated in frequency to regenerate chrominance signal combined with the unfolded luminance signal with its high frequencies re-emphasized to their original amplitude, regenerating a composite signal descriptive of a full bandwidth image. The motion signal is utilized in the encoder for motion-adaptively pre-filtering the input luminance and is recovered in the decoder for motion-adaptively post-filtering the unfolded luminance.

Claims

1. A video signal processing system for transmitting a wide bandwidth video signal via a limited bandwidth medium, comprising:

encoder means connectable to a limited bandwidth video medium, for receiving an input video signal including at least a wide bandwidth luminance signal having low frequency and high frequency luminance components and for producing therefrom a limited bandwidth luminance signal having a low frequency luminance band with a bandwidth limited to a limited bandwidth and a high frequency luminance band component de-emphasized in amplitude from said input video signal and folded into a bandwidth of said low frequency luminance band component, wherein the amount of de-emphasis of said high frequency luminance band component varies in dependence on an amplitude thereof in the input video signal.

2. The video signal processing system according to claim 1, wherein the amount of de-emphasis of said high frequency luminance band component varies in proportion to the amplitude thereof in the input video signal.

3. The video signal processing system according to claim 1, wherein the amount of de-emphasis of said high frequency luminance band component varies in monotonically increasing relation to an average energy thereof in the input video signal.

4. The video signal processing system according to claim 1, wherein the encoder means comprises:

band filtering means for receiving said wide bandwidth luminance signal and producing therefrom a low frequency luminance band component having a bandwidth limited to said limited bandwidth and a high frequency luminance band component;

de-emphasis means for de-emphasizing said high frequency luminance band component in dependence upon the amplitude thereof; and

folding means for folding said high frequency luminance band component into a spectrum of said low frequency luminance band component.

5. The video signal processing system according to claim 4, wherein said de-emphasis means comprises:

gain control signal generator means for generating a de-emphasis gain control signal which varies in monotonically decreasing relation to an average energy of said high frequency luminance band component; and

de-emphasis gain means for attenuating an amplitude of said high frequency luminance band component in accordance with said de-emphasis gain control signal.

6. The video signal processing system of claim 5, wherein said gain control signal generator means comprises:

absolute value means for generating an absolute value signal representing an absolute value of said high frequency luminance band component;

lowpass filter means for lowpass filtering said absolute value signal to provide an average energy signal representing an average energy of said high frequency luminance band component; and

look-up table means for generating a de-emphasis gain control signal varying in value in accordance with said average energy signal.

7. The video signal processing system according to claim 5, wherein said de-emphasis gain means comprises:

multiplier means for multiplying said high frequency luminance band component by said de-emphasis gain control signal.

8. The video signal processing system according to claim 4, wherein said de-emphasis means comprises:

absolute value means for generating an absolute value signal representing an absolute value of said high frequency luminance band component;

lowpass filter means for lowpass filtering said absolute value signal to provide an average energy signal representing an average energy of said high frequency luminance band component;

look-up table means for generating a de-emphasis gain control signal varying in value in accordance with said average energy signal; and

multiplier means for multiplying said high frequency luminance band component by said de-emphasis gain control signal.

9. The video signal processing system according to claim 4, wherein the amount of de-emphasis of said high frequency luminance band component effected by said de-emphasis means varies in proportion to the amplitude thereof in the input video signal.

10. The video signal processing system according to claim 4, wherein the amount of de-emphasis of said high frequency luminance band component effected by said de-emphasis means varies in monotonically increasing relation to an average energy thereof in the input video signal.

11. The video signal processing system according to claim 1, wherein the encoder means comprises:

band filtering means for receiving said wide bandwidth luminance signal and for producing therefrom a low frequency luminance band component having a bandwidth limited to said limited bandwidth and a high frequency luminance band component;

de-emphasis means for de-emphasizing said high frequency luminance band component in dependence upon the amplitude thereof; and

folding means for folding said de-emphasized high frequency luminance band component into said low frequency luminance band component.

12. The video signal processing system according to claim 11, wherein said de-emphasis means comprises:

gain control signal generator means for generating a de-emphasis gain control signal which varies in monotonically decreasing relation to an average energy of said high frequency luminance band component; and

de-emphasis gain means for attenuating an amplitude of said high frequency luminance band component in accordance with said de-emphasis gain control signal..

13. The video signal processing system of claim 12, wherein said gain control signal generator means comprises:

absolute value means for generating an absolute value signal representing an absolute value of said high frequency luminance band component;

lowpass filter means for lowpass filtering said absolute value signal to provide an average energy signal representing an average energy of said high frequency luminance band component; and

look-up table means for generating a de-emphasis gain control signal varying in value in accordance with said average energy signal.

14. The video signal processing system according to claim 12, wherein said de-emphasis gain means comprises:

multiplier means for multiplying said high frequency luminance band component by said de-emphasis gain control signal.

15. The video signal processing system according to claim 11, wherein said de-emphasis means comprises:

absolute value means for generating an absolute value signal representing an absolute value of said high frequency luminance band component;

lowpass filter means for lowpass filtering said absolute value signal to provide an average energy signal representing an average energy of said high frequency luminance band component;

look-up table means for generating a de-emphasis gain control signal varying in value in accordance with said average energy signal; and

multiplier means for multiplying said high frequency luminance band component by said de-emphasis gain control signal.

16. The video signal processing system according to claim 11, wherein the amount of de-emphasis of said high frequency luminance band component effected by said de-emphasis means varies in proportion to the amplitude thereof in the input video signal.

17. The video signal processing system according to claim 11, wherein the amount of de-emphasis of said high frequency luminance band component effected by said de-emphasis means varies in monotonically increasing relation to an average energy thereof in the input video signal.

18. The video signal processing system according to claim 1, wherein the encoder means comprises:

folding means for folding said high frequency luminance component into said low frequency luminance component; and

de-emphasis means for de-emphasizing said high frequency luminance component in dependence upon the amplitude thereof.

19. The video signal processing system according to claim 18, wherein said de-emphasis means comprises:

gain control signal generator means for generating a de-emphasis gain control signal which varies in monotonically decreasing relation to an average energy of said high frequency luminance component; and

de-emphasis gain means for attenuating an amplitude of said high frequency luminance component in accordance with said de-emphasis gain control signal.

20. The video signal processing system of claim 19, wherein said gain control signal generator means comprises:

absolute value means for generating an absolute value signal representing an absolute value of said high frequency luminance component;

lowpass filter means for lowpass filtering said absolute value signal to provide an average energy signal representing an average energy of said high frequency luminance component; and

look-up table means for generating a de-emphasis gain control signal varying in value in accordance with said average energy signal.

21. The video signal processing system according to claim 19, wherein said de-emphasis gain means comprises:

multiplier means for multiplying said high frequency luminance component by said de-emphasis gain control signal.

22. The video signal processing system according to claim 18, wherein said de-emphasis means comprises:

absolute value means for generating an absolute value signal representing an absolute value of said high frequency luminance component;

lowpass filter means for lowpass filtering said absolute value signal to provide an average energy signal representing an average energy of said high frequency luminance component;

look-up table means for generating a de-emphasis gain control signal varying in value in accordance with said average energy signal; and

multiplier means for multiplying said high frequency luminance component by said de-emphasis gain control signal.

23. The video signal processing system according to claim 18, wherein the amount of de-emphasis of said high frequency luminance component effected by said de-emphasis means varies in proportion to the amplitude thereof in the input video signal.

24. The video signal processing system according to claim 18, wherein the amount of de-emphasis of said high frequency luminance component effected by said de-emphasis means varies in monotonically increasing relation to an average energy thereof in the input video signal.

25. A video signal processing system for transmitting a wide bandwidth video signal via a limited bandwidth medium, comprising:

encoder means connectable to a limited bandwidth video medium, for receiving an input video signal including at least an input wide bandwidth luminance signal and for producing therefrom a limited bandwidth video signal including a limited bandwidth luminance signal having a high frequency luminance component of said input wide bandwidth luminance signal de-emphasized in amplitude from said input video signal and folded into a bandwidth of a low frequency luminance component limited to said limited bandwidth, wherein the amount of de-emphasis of said high frequency luminance component varies in dependence on the amplitude thereof in the input video signal, and for also generating a motion signal representative of a degree of image motion in said input video signal; and

means for transmitting said motion signal together with said limited bandwidth video signal.

26. The video signal processing system according to claim 25, wherein the amount of de-emphasis of said high frequency luminance component varies in proportion to the amplitude thereof in the input video signal.

27. The video signal processing system according to claim 25, wherein the amount of de-emphasis of said high frequency luminance component varies in monotonically increasing relation to an average energy thereof in the input video signal.

28. The video signal processing system according to claim 25, wherein the encoder means comprises:

band filtering means for receiving said wide bandwidth luminance signal and producing therefrom a low frequency luminance band component having its bandwidth limited to a limited bandwidth and a high frequency luminance band component;

de-emphasis means for de-emphasizing said high frequency luminance band component in dependence upon the amplitude thereof;

folding means for folding said high frequency luminance band component into a frequency spectrum of said low frequency luminance band component; and

motion signal generation means for generating said motion signal representative of the degree of image motion in said wide bandwidth luminance signal.

29. The video signal processing system according to claim 28, wherein said de-emphasis means comprises:

gain control signal generator means for generating a de-emphasis gain control signal which varies in monotonically decreasing relation to an average energy of said high frequency luminance band component; and

de-emphasis gain means for attenuating an amplitude of said high frequency luminance band component in accordance with said de-emphasis gain control signal.

30. The video signal processing system of claim 29, wherein said gain control signal generator means comprises:

absolute value means for generating an absolute value signal representing an absolute value of said high frequency luminance band component;

lowpass filter means for lowpass filtering said absolute value signal to provide an average energy signal representing an average energy of said high frequency luminance band component; and

look-up table means for generating a de-emphasis gain control signal varying in value in accordance with said average energy signal.

31. The video signal processing system according to claim 29, wherein said de-emphasis gain means comprises:

multiplier means for multiplying said high frequency luminance band component by said de-emphasis gain control signal.

32. The video signal processing system according to claim 28, wherein said de-emphasis means comprises:

absolute value means for generating an absolute value signal representing an absolute value of said high frequency luminance band component;

lowpass filter means for lowpass filtering said absolute value signal to provide an average energy signal representing an average energy of said high frequency luminance band component;

look-up table means for generating a de-emphasis gain control signal varying in value in accordance with said average energy signal; and

multiplier means for multiplying said high frequency luminance band component by said de-emphasis gain control signal.

33. The video signal processing system according to claim 28, wherein the amount of de-emphasis of said high frequency luminance band component effected by said de-emphasis means varies in proportion to the amplitude thereof in the input video signal.

34. The video signal processing system according to claim 28, wherein the amount of de-emphasis of said high frequency luminance band component effected by said de-emphasis means varies in monotonically increasing relation to an average energy thereof in the input video signal.

35. The video signal processing system according to claim 28, wherein said motion signal is spread horizontally and vertically by sa id motion signal generation means.

36. The video signal processing means of claim 28, where in said motion signal is spread horizontally, vertically and temporally.

37. The video signal processing means of claim 28, wherein said motion signal generating means includes spreading means for spreading said motion signal spatially.

38. The video signal processing means of claim 28, wherein said motion signal generating means includes spreading means for spreading said motion signal spatially and temporally.

39. The video signal processing means of claim 28, wherein the wide bandwidth luminance signal which said band splitting means operates upon is a spatio-temporally filtered wide bandwidth luminance signal and wherein said encoder means further comprises:

spatial filter means for spatially filtering the wide bandwidth luminance signal to produce a spatially filtered luminance signal;

temporal filter means for temporally filtering the wide bandwidth luminance signal to produce a temporally filtered luminance signal; and

motion-adaptive means for varying, in response to said motion signal, a proportion of said spatially filtered luminance signal and a proportion of said temporally filtered luminance signal in said wide bandwidth spatio-temporally filtered luminance signal supplied to said band splitting means.

40. The video signal processing means of claim 39, wherein said motion signal is spread horizontally and vertically by said motion signal generation means.

41. The video signal processing means of claim 39, wherein said motion signal is spread horizontally, vertically and temporally by said motion signal generation means.

65. The video signal processing means of claim 58 28, wherein said chrominance/motion combining means adds said motion signal into a vacant portion of said chrominance signal component for producing said composite chrominance-plus-motion signal.

42. A video signal processing system for transmitting a wide bandwidth video signal via a limited bandwidth medium, comprising:

encoder means having an input terminal connectable to a source of composite video signals and an output terminal connectable to a limited bandwidth video medium,

for receiving at said input terminal an input composite video signal including a wide bandwidth baseband luminance signal component having low frequency and high luminance frequencies together with a chrominance signal component, and for producing therefrom a limited bandwidth luminance signal having a high frequency luminance component de-emphasized in amplitude from said input video signal and folded into a bandwidth of a low frequency luminance component which is limited to a limited bandwidth, wherein the amount of de-emphasis of said high frequency luminance component varies in dependence on an amplitude thereof in the input video signal;

for deriving from said input video signal a motion signal representative of a degree of image motion in said input video signal;

for spatially filtering said baseband luminance signal to produce a spatially filtered luminance signal;

for temporally filtering said baseband luminance signal to produce a temporally filtered luminance signal;

for varying, in response to said motion signal, a proportion of said spatially filtered luminance signal and a proportion of said temporally filtered luminance signal in said limited bandwidth luminance signal;

for combining said motion signal with said chrominance signal to produce a composite chrominance-plus-motion signal; and

for providing said limited bandwidth luminance signal and said chrominance-plus-motion signal at said output terminal.

43. The video signal processing system according to claim 42, wherein the amount of de-emphasis of said high frequency luminance component varies in proportion to the amplitude thereof in the input video signal.

44. The video signal processing system according to claim 42, wherein the amount of de-emphasis of said high frequency luminance component varies in monotonically increasing relation to an average energy thereof in the input video signal.

45. The video signal processing means of claim 42, wherein said motion signal is spread horizontally and vertically by said encoder means.

46. The video signal processing means of claim 42, wherein said motion signal is spread horizontally, vertically and temporally by said encoder means.

47. The video signal processing means of claim 42, wherein said motion signal is added into a vacant portion of said chrominance signal for producing said composite chrominance-plus-motion signal.

48. The video signal processing system of claim 42, wherein the chrominance signal component of said chrominance-plus-motion signal is a color-under chrominance signal.

49. The video signal processing system according to claim 42, wherein the encoder means comprises:

chrominance/luminance separation means for separating said input composite video signal into its said wide bandwidth baseband luminance signal and chrominance signal components;

motion signal generation means for deriving said motion signal from said wide bandwidth baseband luminance signal;

spatial filter means for spatially filtering the wide bandwidth baseband luminance signal to produce a spatially filtered baseband luminance signal;

temporal filter means for temporally filtering the wide bandwidth baseband luminance signal to produce a temporally filtered baseband luminance signal;

motion-adaptive means for varying, in response to said motion signal, respective proportions of said spatially filtered baseband luminance signal and said temporally filtered baseband luminance signal which are output as a spatio-temporally filtered baseband luminance signal;

band filtering means for receiving said spatio-temporally filtered baseband luminance signal and producing therefrom a low frequency luminance band component having a bandwidth limited to said limited bandwidth and a high frequency luminance band component;

de-emphasis means for adaptively de-emphasizing said high frequency luminance band component in dependence upon the amplitude thereof;

folding means for folding said high frequency luminance band component into the bandwidth of said low frequency luminance band component to provide said limited bandwidth luminance signal and for coupling said limited bandwidth luminance signal to said output terminal of said encoder means; and

chrominance/motion combining means for combining said chrominance and motion signals into a composite chrominance-plus-motion signal and for coupling said chrominance-plus-motion signal to said output terminal of said encoder means.

50. The video signal processing system according to claim 49, wherein said de-emphasis means comprises:

gain control signal generator means for generating a de-emphasis gain control signal which varies in monotonically decreasing relation to an average energy of said high frequency luminance band component; and

de-emphasis gain means for attenuating an amplitude of said high frequency luminance band component in accordance with said de-emphasis gain control signal.

51. The video signal processing system of claim 50, wherein said gain control signal generator means comprises:

absolute value means for generating an absolute value signal representing an absolute value of said high frequency luminance band component;

lowpass filter means for lowpass filtering said absolute value signal to provide an average energy signal representing an average energy of said high frequency luminance band component; and

look-up table means for generating a de-emphasis gain control signal varying in value in accordance with said average energy signal.

52. The video signal processing system according to claim 50, wherein said de-emphasis gain means comprises:

multiplier means for multiplying said high frequency luminance band component by said de-emphasis gain control signal.

53. The video signal processing system according to claim 50, wherein said de-emphasis means comprises:

absolute value means for generating an absolute value signal representing an absolute value of said high frequency luminance band component;

lowpass filter means for lowpass filtering said absolute value signal to provide an average energy signal representing an average energy of said high frequency luminance band component;

look-up table means for generating a de-emphasis gain control signal varying in value in accordance with said average energy signal; and

multiplier means for multiplying said high frequency luminance band component by said de-emphasis gain control signal.

54. The video signal processing system of claim 50, wherein the amount of de-emphasis of said high frequency luminance band component effected by said de-emphasis means varies in proportion to the amplitude thereof in the input video signal.

55. The video signal processing system according to claim 50, wherein the amount of de-emphasis of said high frequency luminance band component effected by said de-emphasis means varies in monotonically increasing relation to an average energy thereof in the input video signal.

56. The video signal processing system according to claim 50, wherein said motion signal generation means spreads said derived motion signal spatially.

57. The video signal processing system according to claim 50, wherein said motion signal generation means spreads said derived motion signal spatially and temporally.

58. A video signal processing system for converting an input wide bandwidth composite video signal including a wide bandwidth baseband luminance signal component and a chrominance component into a limited bandwidth video signal, comprising:

chrominance/luminance separation means for separating said input wide bandwidth composite video signal into its said wide bandwidth baseband luminance signal and chrominance signal components;

motion signal generation means for deriving from said wide bandwidth baseband luminance signal a motion signal representative of a degree of image motion in said input wide bandwidth composite video signal;

spatial filter means for spatially filtering the wide bandwidth baseband luminance signal to produce a spatially filtered baseband luminance signal;

temporal filter means for temporally filtering the wide bandwidth baseband luminance signal to produce a temporally filtered baseband luminance signal;

motion-adaptive means for varying, in response to said motion signal, respective proportions of said spatially filtered baseband luminance signal and said temporally filtered baseband luminance signal which are output as a spatio-temporally filtered baseband luminance signal;

band filtering means for receiving said spatio-temporally filtered baseband luminance signal and producing therefrom a low frequency luminance band component having a bandwidth limited to said limited bandwidth and a high frequency luminance band component;

de-emphasis means for adaptively de-emphasizing said high frequency luminance band component in dependence upon an amplitude thereof;

folding means for folding said high frequency luminance band component into the bandwidth of said low frequency luminance band component to provide a folded limited bandwidth luminance signal; and

chrominance/motion combining means for combining said chrominance signal component and said motion signal into a composite chrominance-plus-motion signal.

59. The video signal processing system according to claim 58, wherein said de-emphasis means comprises:

gain control signal generator means for generating a de-emphasis gain control signal which varies in monotonically decreasing relation to an average energy of said high frequency luminance band component; and

de-emphasis gain means for attenuating an amplitude of said high frequency luminance band component in accordance with said de-emphasis gain control signal.

60. The video signal processing system of claim 59, wherein said gain control signal generator means comprises:

absolute value means for generating an absolute value signal representing an absolute value of said high frequency luminance band component;

lowpass filter means for lowpass filtering said absolute value signal to provide an average energy signal representing an average energy of said high frequency luminance band component; and

look-up table means for generating a de-emphasis gain control signal varying in value in accordance with said average energy signal.

61. The video signal processing system according to claim 59, wherein said de-emphasis gain means comprises:

multiplier means for multiplying said high frequency luminance band component by said de-emphasis gain control signal.

62. The video signal processing system according to claim 58, wherein said de-emphasis means comprises:

absolute value means for generating an absolute value signal representing an absolute value of said high frequency luminance band component;

lowpass filter means for lowpass filtering said absolute value signal to provide an average energy signal representing an average energy of said high frequency luminance band component;

look-up table means for generating a de-emphasis gain control signal varying in value in accordance with said average energy signal; and

multiplier means for multiplying said high frequency luminance band component by said de-emphasis gain control signal.

63. The video signal processing system of claim 58, wherein the amount of de-emphasis of said high frequency luminance band component effected by said de-emphasis means varies in proportion to the amplitude thereof.

64. The video signal processing system according to claim 58, wherein the amount of de-emphasis of said high frequency luminance band component effected by said de-emphasis means varies in monotonically increasing relation to an average energy thereof.

66. The video signal processing system of claim 58, wherein the chrominance signal component combined with said motion signal by said chrominance/motion combining means is a color-under chrominance signal.

67. The video signal processing system of claim 58, further comprising:

luminance signal recording means for recording said folded limited bandwidth luminance signal onto a recording medium; and

chrominance signal recording means for recording said chrominance-plus-motion signal onto said recording medium.

68. The video signal processing system of claim 67, wherein the recording medium is magnetic tape in a video cassette.

69. The video signal processing system of claim 58, wherein the chrominance/motion combining means comprises:

chrominance signal modulation means for modulating said chrominance signal component onto a chrominance carrier to provide a modulated chrominance signal component such that at any one time said modulated chrominance signal component occupies only a portion of said chrominance signal carrier and another portion of said chrominance signal carrier is vacant of said modulated chrominance signal component;

motion signal modulation means for modulating said motion signal onto a motion signal carrier to provide a modulated motion signal such that at said any one time said modulated motion signal occupies only a portion of said motion signal carrier corresponding to said vacant portion of said chrominance signal carrier not occupied by said modulated chrominance signal component; and

means for adding said modulated chrominance signal component and said modulated motion signal component to provide said composite chrominance-plus-motion signal, whereby said modulated motion signal component is always 180°

out of phase with said modulated chrominance signal component in said chrominance-plus-motion signal.

70. A video signal processing system for converting a limited bandwidth folded video luminance signal into a wide bandwidth unfolded video luminance signal, comprising:

decoder means for unfolding a limited bandwidth folded video luminance signal including a low frequency luminance band component having a bandwidth limited to said limited bandwidth and a high frequency luminance band component folded into a spectrum of said low frequency luminance band component to provide therefrom an unfolded baseband luminance signal having a bandwidth greater than said limited bandwidth and containing the low frequency luminance band component of said limited bandwidth video luminance signal and the high frequency luminance band component unfolded from said limited bandwidth video luminance signal, and for emphasizing said unfolded luminance high frequency band component in amplitude by an amount depending upon a magnitude thereof.

71. The video signal processing system of claim 70, wherein the amount of emphasis of said high frequency luminance band component varies in proportion to an amplitude thereof.

72. The video signal processing system of claim 70, wherein the amount of emphasis of said high frequency luminance band component varies in monotonically decreasing relation to an average energy thereof.

73. The video signal processing system of claim 70, wherein the decoder means comprises:

unfolding means for unfolding said limited bandwidth video luminance signal to provide said unfolded baseband luminance signal; and

emphasis means for emphasizing said unfolded high frequency luminance band component by an amount dependent upon an amplitude thereof.

74. The video signal processing system of claim 73, wherein the amount of emphasis effected upon said high frequency luminance band component by said emphasis means varies in proportion to the amplitude thereof.

75. The video signal processing system of claim 73, wherein the amount of emphasis effected upon said high frequency luminance band component by said emphasis means varies in monotonically decreasing relation to an average energy thereof.

76. The video signal processing system according to claim 73, wherein said emphasis means comprises:

gain control signal generator means for generating an emphasis gain control signal which varies in monotonically increasing relation to an average energy of said unfolded high frequency luminance band component; and

emphasis gain means for boosting an amplitude of said unfolded high frequency luminance band component in accordance with said emphasis gain control signal.

77. The video signal processing system of claim 76, wherein said gain control signal generator means comprises:

absolute value means for generating an absolute value signal representing an absolute value of said unfolded high frequency luminance band component;

lowpass filter means for lowpass filtering said absolute value signal to provide an average energy signal representing an average energy of said unfolded high frequency luminance band component; and

look-up table means for generating an emphasis gain control signal varying in value in accordance with said average energy signal.

78. The video signal processing system according to claim 76, wherein said emphasis gain means comprises:

multiplier means for multiplying said unfolded high frequency luminance band component by said emphasis gain control signal.

79. The video signal processing system according to claim 73, wherein said emphasis means comprises:

absolute value means for generating an absolute value signal representing an absolute value of said unfolded high frequency luminance band component;

lowpass filter means for lowpass filtering said absolute value signal to provide an average energy signal representing an average energy of said unfolded high frequency luminance band component;

look-up table means for generating an emphasis gain control signal varying in value in accordance with said average energy signal; and

multiplier means for multiplying said unfolded high frequency luminance band component by said emphasis gain control signal.

80. A video signal processing system, comprising:

unfolding means for unfolding a limited bandwidth folded video luminance signal containing a low frequency luminance band component having a bandwidth limited to a limited bandwidth and a high frequency luminance band component folded into a spectrum of said low frequency luminance band component to provide therefrom an unfolded baseband luminance signal having a bandwidth greater than said limited bandwidth and containing said low frequency luminance band component of said folded video luminance signal and said high frequency luminance band component unfolded from said folded video luminance signal;

spatial filter means for spatially filtering the unfolded baseband luminance signal to produce a spatially filtered baseband luminance signal;

temporal filter means for temporally filtering the unfolded baseband luminance signal to produce a temporally filtered baseband luminance signal;

chrominance/motion separation means for separating a composite chrominance-plus-motion signal containing a video chrominance signal component combined with a motion signal component representative of a degree of motion in a video image to provide therefrom a separated chrominance signal and a separated motion signal;

motion-adaptive means for varying, in response to said motion signal, respective proportions of said spatially filtered baseband luminance signal and said temporally filtered baseband luminance signal which are output as a spatio-temporally filtered baseband luminance signal;

band filtering means for receiving said spatio-temporally filtered baseband luminance signal and producing therefrom a spatio-temporally filtered low frequency luminance band component having a bandwidth limited to said limited bandwidth and a spatio-temporally filtered high frequency luminance band component;

emphasis means for adaptively emphasizing said spatio-temporally filtered high frequency luminance band component in amplitude in dependence upon a magnitude thereof to provide an emphasized spatio-temporally filtered high frequency luminance band component; and

combining means for contiguously combining said emphasized spatio-temporally filtered high frequency luminance band component with said spatio-temporally filtered low frequency luminance band component to provide a wide bandwidth luminance signal.

81. The video signal processing system according to claim 80, wherein said emphasis means emphasizes said spatio-temporally filtered high frequency luminance band component in amplitude by an amount which varies in proportion to an amplitude of said spatio-temporally filtered high frequency luminance band component.

82. The video signal processing system according to claim 80, wherein said emphasis means emphasizes said spatio-temporally filtered high frequency luminance band component in amplitude by an amount which varies in monotonically increasing relation to an average energy of said spatio-temporally filtered high frequency luminance band component.

83. The video signal processing system according to claim 80, wherein said chrominance signal component is a color-under chrominance signal.

84. The video signal processing system according to claim 80, wherein said emphasis means comprises:

gain control signal generator means for generating an emphasis gain control signal which varies in monotonically increasing relation to an average energy of said spatio-temporally filtered high frequency luminance band component; and

emphasis gain means for boosting an amplitude of said spatio-temporally filtered high frequency luminance band component in accordance with said emphasis gain control signal.

85. The video signal processing system of claim 84, wherein said gain control signal generator means comprises:

absolute value means for generating an absolute value signal representing an absolute value of said spatio-temporally filtered high frequency luminance band component;

lowpass filter means for lowpass filtering said absolute value signal to provide an average energy signal representing an average energy of said spatio-temporally filtered high frequency luminance band component; and

look-up table means for generating an emphasis gain control signal varying in value in accordance with said average energy signal.

86. The video signal processing system according to claim 84, wherein said emphasis gain means comprises:

multiplier means for multiplying said spatio-temporally filtered high frequency luminance band component by said emphasis gain control signal.

87. The video signal processing system according to claim 80, wherein said emphasis means comprises:

absolute value means for generating an absolute value signal representing an absolute value of said spatio-temporally filtered high frequency luminance band component;

lowpass filter means for lowpass filtering said absolute value signal to provide an average energy signal representing an average energy of said spatio-temporally filtered high frequency luminance band component;

look-up table means for generating an emphasis gain control signal varying in value in accordance with said average energy signal; and

multiplier means for multiplying said spatio-temporally filtered high frequency luminance band component by said emphasis gain control signal.

88. The video signal processing system according to claim 80, further comprising:

luminance signal playback means for reproducing said folded video luminance signal from a recording medium; and

chrominance signal playback means for reproducing said chrominance-plus-motion signal from said recording medium.

89. The video signal processing system according to claim 88, wherein said recording medium is magnetic tape in a video cassette.

90. A video signal processing system, comprising:

encoder means for encoding an input video signal including at least an input wide bandwidth luminance signal having low and high luminance frequencies to produce therefrom a limited bandwidth video signal containing at least an encoded limited bandwidth luminance signal having a low frequency luminance band component with a bandwidth limited to a limited bandwidth together with a high frequency luminance band component de-emphasized in magnitude from a magnitude thereof in said input wide bandwidth luminance signal and folded into a bandwidth of said low frequency luminance band component and with the amount of de-emphasis of said high frequency luminance band component varying in dependence upon the magnitude thereof in said input wide bandwidth luminance signal; and

decoder means for decoding said limited bandwidth video signal to produce therefrom an output video signal including at least a decoded wide bandwidth luminance signal having a bandwidth greater than said limited bandwidth and containing said low frequency luminance band component along with said high frequency luminance band component unfolded from said limited bandwidth signal, and for re-emphasizing said unfolded high frequency luminance band component in magnitude by an amount corresponding to said amount of de-emphasis thereof by said encoder means for thereby restoring said high frequency luminance band component to said magnitude thereof in said input wide bandwidth luminance signal.

91. The video signal processing system of claim 90, wherein the amount of de-emphasis of said high frequency luminance band component effected by said encoder means and the amount of re-emphasis of said high frequency luminance band component effected by said decoder means both vary in proportion to the respective magnitudes thereof.

92. The video signal processing system of claim 90, wherein the amount of de-emphasis of said high frequency luminance band component effected by said encoder means varies in monotonically increasing relation to an average energy thereof, and wherein the amount of re-emphasis of said unfolded high frequency luminance band component effected by said decoder means varies in monotonically decreasing relation to an average energy thereof.

93. A method for processing a wide bandwidth video signal into a limited bandwidth video signal, comprising the steps of:

receiving a wide bandwidth video signal including at least a baseband video luminance signal and producing therefrom a low frequency luminance component having a bandwidth limited to a limited bandwidth and a high frequency luminance component;

reducing said high frequency luminance component in amplitude by an amount which varies in dependence upon an amplitude thereof for de-emphasizing said high frequency luminance component;

shifting a frequency spectrum of said high frequency luminance component to a frequency spectrum of said low frequency luminance component for providing a folded high frequency luminance component; and

adding said folded high frequency luminance component to said low frequency luminance component for providing a folded video luminance signal having a bandwidth limited to said limited bandwidth.

94. The method according to claim 93, wherein the amount of de-emphasis of said high frequency luminance component varies in proportion to an amplitude of said high frequency luminance component.

95. The method according to claim 93, wherein the amount of de-emphasis of said high frequency luminance component varies in monotonically increasing relation to an average energy of said high frequency luminance component.

96. The method of claim 93, wherein said step of de-emphasizing said high frequency luminance component comprises the substeps of:

generating an absolute value signal representing an absolute value of said high frequency luminance component;

lowpass filtering said absolute value signal to provide an average energy signal representing an average energy of said high frequency component;

generating a de-emphasis gain control signal varying in monotonically decreasing relation to said average energy signal; and

multiplying said high frequency luminance component by said emphasis gain control signal.

97. A method for processing a wide bandwidth video luminance signal into a limited bandwidth video luminance signal, comprising the steps of:

receiving a wide bandwidth video luminance signal and producing therefrom a low frequency luminance component having a bandwidth limited to a limited bandwidth and a high frequency luminance component having a bandwidth not exceeding said limited bandwidth;

reducing said high frequency luminance component in amplitude by an amount which varies in dependence upon an amplitude thereof, for de-emphasizing high frequency luminance component;

shifting said high frequency luminance component to a frequency spectrum of said low frequency luminance component for providing a folded high frequency luminance component; and

adding said folded high frequency luminance component to said low frequency luminance component for producing a folded video luminance signal having a bandwidth limited to said limited bandwidth.

98. The method according to claim 97, wherein the amount of de-emphasis of said high frequency luminance component varies in proportion to an amplitude of said high frequency luminance component.

99. The method according to claim 97, wherein the amount of de-emphasis of said high frequency luminance component varies in monotonically increasing relation to an average energy of said high frequency luminance component.

100. The method of claim 97, wherein said step of de-emphasizing said high frequency luminance component comprises the substeps of:

generating an absolute value signal representing an absolute value of said high frequency luminance component;

lowpass filtering said absolute value signal to provide an average energy signal representing an average energy of said high frequency component;

generating a de-emphasis gain control signal varying in monotonically decreasing relation to said average energy signal; and

multiplying said high frequency luminance component by said de-emphasis gain control signal.

101. A method for converting a limited bandwidth video luminance signal into a wide bandwidth baseband video luminance signal, comprising the steps of:

receiving a limited bandwidth video luminance signal having a low frequency luminance component with a bandwidth limited to a limited bandwidth and a high frequency luminance component folded into a frequency spectrum of said low frequency luminance component and de-emphasized in amplitude in relation to an original amplitude thereof;

unfolding said limited bandwidth video luminance signal for providing an unfolded baseband luminance signal having said low frequency luminance component of said limited bandwidth video luminance signal together with said high frequency luminance component of said limited bandwidth video luminance signal in unfolded form, whereby a bandwidth of said unfolded baseband luminance signal is greater than said limited bandwidth; and

increasing said unfolded high frequency luminance component in amplitude by an amount which varies in dependence upon an amplitude thereof, for providing a wide bandwidth baseband video luminance signal having said low frequency luminance component and said unfolded high frequency luminance component, said unfolded high frequency luminance component being thereby emphasized in amplitude.

102. The method according to claim 101, wherein the amount of emphasis of said unfolded high frequency luminance component varies in proportion to the amplitude thereof.

103. The method according to claim 101, wherein the amplitude of said unfolded high frequency luminance component is increased by an amount which varies in monotonically increasing relation to an average energy thereof.

104. A method for converting a full bandwidth video luminance signal into a limited bandwidth video luminance signal retaining therein luminance information of the full bandwidth luminance signal within a limited bandwidth, and for reconverting the limited bandwidth video luminance signal into a wide bandwidth baseband luminance signal corresponding to the full bandwidth video luminance signal, comprising the steps of:

receiving said full bandwidth video luminance signal and producing therefrom a low frequency luminance component having a bandwidth limited to a limited bandwidth and a high frequency luminance component having a bandwidth not exceeding said limited bandwidth;

reducing said high frequency luminance component in amplitude by an amount dependent upon the amplitude of said high frequency luminance component;

shifting said high frequency luminance component to a frequency spectrum of said low frequency luminance component for producing a folded high frequency luminance component; and

adding said folded high frequency luminance component to said low frequency luminance component for producing a limited bandwidth video luminance signal;

unfolding said limited bandwidth video luminance signal for providing an unfolded baseband luminance signal having said low frequency luminance component of said limited bandwidth video luminance signal and said folded high frequency luminance component of said limited bandwidth video luminance signal in unfolded form; and

increasing said unfolded high frequency luminance component in amplitude by an amount which varies in dependence upon the amplitude thereof, for providing a wide bandwidth baseband video luminance signal having said low frequency luminance component and said unfolded high frequency luminance component, said unfolded high frequency luminance component being thereby emphasized in amplitude.

105. The method according to claim 104, wherein the amount of de-emphasis of said high frequency luminance component and the amount of emphasis of said unfolded high frequency luminance component both vary in proportion to the respective amplitudes thereof.

106. The method according to claim 105, wherein the amount of de-emphasis of said high frequency luminance component varies in monotonically increasing relation to an average energy thereof, and wherein the amount of emphasis of said unfolded high frequency luminance component varies in monotonically decreasing relation to an average energy thereof.

107. A recording on a narrow bandwidth video medium of a limited bandwidth video signal, said limited bandwidth video signal comprising:

a limited bandwidth luminance signal component carrying luminance information of an original wide bandwidth luminance signal and including;

a low frequency luminance band component corresponding to a low frequency band of said original wide bandwidth luminance signal and having a bandwidth limited to said narrow bandwidth; and

a high frequency luminance band component corresponding to a high frequency band of said original wide bandwidth luminance signal and folded into a frequency spectrum of said low frequency luminance band component, said high frequency luminance band component being de-emphasized in amplitude with respect to said high frequency band of said original wide bandwidth luminance signal.

108. A recording on a narrow bandwidth video medium, as set forth in claim 107, wherein the amount of de-emphasis of said high frequency luminance band component varies in proportion to an amplitude of said high frequency band of said original wide bandwidth luminance signal.

109. A recording on a narrow bandwidth video medium, as set forth in claim 107, wherein the amount of de-emphasis of said high frequency luminance band component varies in monotonically increasing relation to an average energy of said high frequency band of said original wide bandwidth luminance signal.

110. A recording on a narrow bandwidth video medium, as set forth in claim 107, further comprising:

a motion signal component carrying information representative of a degree of image motion in said original wide bandwidth luminance signal.

111. A recording on a narrow bandwidth video medium, as set forth in claim 107, further comprising:

a chrominance signal component carrying chrominance information.

112. A recording on a narrow bandwidth video medium of a limited bandwidth video signal, said limited bandwidth video signal comprising:

a limited bandwidth luminance signal component carrying luminance information of an original wide bandwidth video signal and including;

a low frequency luminance band component corresponding to a low frequency luminance band of said original wide bandwidth video signal and having a bandwidth limited to said narrow bandwidth; and

a high frequency luminance band component corresponding to a high frequency luminance band of said original wide bandwidth video signal and folded into a frequency spectrum of said low frequency luminance band component, said high frequency luminance band component being de-emphasized in amplitude with respect to said high frequency luminance band of said original wide bandwidth video signal;

a chrominance signal component carrying chrominance information of said original wide bandwidth video signal; and

a motion signal component carrying information representative of a degree of image motion in said original wide bandwidth video signal.

113. A recording on a narrow bandwidth video medium, as set forth in claim 112, wherein the amount of de-emphasis of said high frequency luminance band component varies in proportion to an amplitude of said high frequency band of said original wide bandwidth video signal.

114. A recording on a narrow bandwidth video medium, as set forth in claim 112, wherein the amount of de-emphasis of said high frequency luminance band component varies in monotonically increasing relation to an average energy of said high frequency band of said original wide bandwidth video signal.

115. A recording on a narrow bandwidth video medium, as set forth in claim 112, wherein said chrominance signal component is a color-under chrominance signal.

116. A recording on a narrow bandwidth video medium, as set forth in claim 112, wherein said chrominance signal component and said motion signal component are combined into a composite chrominance-plus-motion signal.

117. A recording on a narrow bandwidth video medium, as set forth in claim 112, wherein said chrominance signal component is a quadrature amplitude modulated color-under chrominance signal and wherein said motion signal component is carried in quadrants of said color-under chrominance signal complementary to quadrants occupied at any one time by said chrominance signal component.

118. A limited bandwidth video signal manifested in electric signal form, comprising:

a limited bandwidth luminance signal component carrying luminance information of an original wide bandwidth luminance signal and including;

a low frequency luminance band component corresponding to a low frequency band of said original wide bandwidth luminance signal and having a bandwidth limited to said narrow bandwidth; and

a high frequency luminance band component corresponding to a high frequency band of said original wide bandwidth luminance signal and folded into a frequency spectrum of said low frequency luminance band component, said high frequency luminance band component being de-emphasized in amplitude with respect to said high frequency band of said original wide bandwidth luminance signal.

119. A limited bandwidth video signal manifested in electric signal form, as set forth in claim 118, wherein the amount of de-emphasis of said high frequency luminance band component varies in proportion to an amplitude of said high frequency band of said original wide bandwidth luminance signal.

120. A limited bandwidth video signal manifested in electric signal form, as set forth in claim 118, wherein the amount of de-emphasis of said high frequency luminance band component varies in monotonically increasing relation to an average energy of said high frequency band of said original wide bandwidth luminance signal.

121. A limited bandwidth video signal manifested in electric signal form, as set forth in claim 118, further comprising:

a motion signal component carrying information representative of a degree of image motion in said original wide bandwidth luminance signal.

122. A limited bandwidth video signal manifested in electric signal form, as set forth in claim 118, further comprising:

a chrominance signal component carrying chrominance information.

123. A limited bandwidth video signal manifested in electric signal form, comprising:

a limited bandwidth luminance signal component carrying luminance information of an original wide bandwidth video signal and including;

a low frequency luminance band component corresponding to a low frequency luminance band of said original wide bandwidth video signal and having a bandwidth limited to said narrow bandwidth; and

a high frequency luminance band component corresponding to a high frequency luminance band of said original wide bandwidth video signal and folded into a frequency spectrum of said low frequency luminance band component, said high frequency luminance band component being de-emphasized in amplitude with respect to said high frequency luminance band of said original wide bandwidth video signal;

a chrominance signal component carrying chrominance information of said original wide bandwidth video signal; and

a motion signal component carrying information representative of a degree of image motion in said original wide bandwidth video signal.

124. A limited bandwidth video signal manifested in electric signal form, as set forth in claim 123, wherein the amount of de-emphasis of said high frequency luminance band component varies in proportion to an amplitude of said high frequency band of said original wide bandwidth video signal.

125. The limited bandwidth video signal according to claim 123, wherein the amount of de-emphasis of said high frequency luminance band component varies in monotonically increasing relation to an average energy of said high frequency band of said original wide bandwidth video signal.

126. The limited bandwidth video signal according to claim 123, wherein said chrominance signal component is a color-under chrominance signal.

127. The limited bandwidth video signal according to claim 123, wherein said chrominance signal component and said motion signal component are combined into a composite chrominance-plus-motion signal.

128. The limited bandwidth video signal according to claim 123, wherein said chrominance signal component is a quadrature amplitude modulated color-under chrominance signal and wherein said motion signal component is carried in quadrants of said color-under chrominance signal complementary to quadrants occupied at any one time by said chrominance signal component.