Method and system using sequentially encoded color and luminance processing of video type signals to improve picture quality

• US 4,335,393 A
• Filed: 04/15/1980
• Issued: 06/15/1982
• Est. Priority Date: 04/15/1980
• Status: Expired due to Term

• Current Assignee: Technology Licensing Corporation
• Original Assignee: Harris Video Systems Incorporated
• Inventors: Pearson, Gilbert J.
• Primary Examiner(s): PSITOS, ARISTOTELIS
• Application Number:
  US06/140,550
• Time in Patent Office: 791 Days
• Field of Search: 358/4, 358/9, 358/12, 358/14, 358/11, 358/6, 358/7, 358/8, 358/15, 358/21 R, 358/27, 358/127, 358/133, 358/134, 358/138, 358/141, 358/142, 358/145, 358/147, 360/8, 360/9, 360/32, 360/33, 360/37
• US Class Current: 386/215
• CPC Class Codes: H04N 11/08 using sequential signals only dot sequential systems H04N11/12
• CPC Class Codes: H04N 9/81 the individual colour picture signal components being recorded sequentially only

Abstract

Conventional composite color video signals are re-formatted into a compressed serial format on a line-by-line basis, by sampling the luminance and chrominance components at a predetermined sampling rate and serially arranging the sampled components on a line-by-line basis to form compressed re-formatted video lines, each containing a pair of serially arranged groups of samples, one of the pair of groups containing luminance samples, the other of the pair of groups containing chrominance samples, the groups being compressed in accordance with a predetermined ratio. The separated luminance and chrominance components of the original video signals are sampled at first and second frequencies f1 and f2, which are related by the expression f2=f1/N where N is the predetermined ratio. The luminance and chrominance samples are stored in a storage device at the first and second clock frequencies, respectively, and are serially arranged by reading the samples from the storage device with a third clock signal f3 having a higher frequency than the other two signal frequencies, one of the two groups of samples being read out in its entirety, followed by a reading out of the other group of samples in its entirety. The luminance signal is compressed by a factor f3/f1, and the chrominance signal is compressed by a factor of N×f3/fl.

To optimize the recovery of the chrominance information during the reconverting phase, a "mezzanine" signal is inserted in each re-formatted video line during the re-formatting phase in the gap between the luminance component and the chrominance component.

Claims

1. A method of re-formatting video type line sequential signals having luminance and chrominance components, each line of said line sequential signals having a predetermined overall temporal length and an active signals portion of predetermined temporal length less than the overall length, said method comprising the steps of:

(a) generating first and second sampling clock signals having frequencies f and f/N, respectively, where N is a finite non-zero value;

(b) sampling said luminance and said chrominance components with said first and second clock signals, respectively;

(c) temporarily storing the component samples in a storage device;

(d) generating a third clock signal having a frequency higher than said first clock signal frequency; and

(e) serially arranging the temporarily stored component samples on a line-by-line basis to form compressed re-formatted video lines each containing a pair of groups of samples, one of said pair of groups containing luminance samples, the other of said pair of groups containing chrominance samples, said groups being compressed in accordance with a predetermined ratio equal to said value N,

said step of serially arranging including the step of first outputting one of said pair of groups of samples under control of said third clock signal and then outputting the other one of said pair of groups of samples under control of said third clock signal, the relative number of luminance samples and chrominance samples and the frequency of said third clock signal being selected so that the temporal length of that portion of each compressed re-formatted video line containing said groups is less than said overall temporal length and greater than said active signal portion temporal length.

2. The method of claim 1 wherein said video type signals are encoded color video signals, and where said step (b) of sampling is preceded by the step of separating said chrominance components from said luminance components.

3. The method of claim 1 wherein N is an integer.

4. The method of claim 1 wherein said step of generating further includes the step of synchronizing said clock signals with a video line reference pulse.

5. The method of claim 4 wherein said line reference pulse comprises the horizontal sync pulse.

6. The method of claim 1 wherein the samples in one of said groups are digital and wherein said step of temporarily storing includes the steps of storing said one of said pair of groups of samples in an analog storage device and storing the other one of said pair of groups of samples in a digital memory.

7. The method of claim 1 wherein said step of temporarily storing includes the step of storing said pair of groups in an analog storage device.

8. The method of claim 1 wherein said samples are digital and wherein said step of temporarily storing includes the step of storing said pair of groups in a digital memory.

9. The method of claim 1 wherein said samples are digital and wherein said step of outputting is followed by the step of converting each re-formatted video line to analog form.

10. The method of claim 9 wherein said step of converting is followed by the step of recording the analog video lines on a recording medium.

11. The method of claim 9 wherein said step of converting is followed by the step of transmitting the analog video lines to a receiving station.

12. The method of claim 9 wherein said video type signals include an original video line reference pulse, and further including the steps of generating a modified video line reference pulse of reduced width from said original line reference pulse, and inserting said modified video line reference pulse at the beginning of each of said re-formatted video lines.

13. The method of claim 12 wherein said original line reference pulse comprises a horizontal sync pulse of conventional time duration.

14. The method of claim 1 wherein said video type signals include two color difference components per line, and wherein said step (e) of serially arranging includes the step of including samples in said other pair of groups corresponding to both said color difference components.

15. The method of claim 1 wherein said video type signals include alternate color difference components in alternate video lines, and wherein said step of serially arranging includes the steps of including samples in said other pair of groups corresponding to one of said alternate color difference components for a first set of re-formatted video lines, and including samples in said other pair of groups corresponding to the other one of said alternate color difference components for a second set of re-formatted video lines.

16. The method of claim 1 wherein said step (e) of serially arranging further includes the steps of generating a color reference level mezzanine signal, and inserting said mezzanine signal in said reformatted video lines at a predetermined line location.

17. The method of claim 16 wherein said mezzanine signal is inserted between said pair of groups.

18. The method of claim 1 wherein each of said re-formatted video lines contains a group of luminance samples followed by a group of chrominance samples.

19. The method of claim 1 wherein each of said re-formatted video lines contains a group of chrominance samples followed by a group of luminance samples.

20. A method of converting sequentially encoded color and luminance (SECAL) video type signals to standard composite video signals having a predetermined overall temporal length and an active signal portion of predetermined temporal length less than the overall length, said SECAL video type signals having luminance and chrominance components re-formatted as compressed video lines of reduced bandwidth, each line containing a pair of groups of video signals, one of said pair of groups containing compressed luminance samples, the other of said pair of groups containing compressed chrominance samples, said groups being compressed in accordance with a predetermined compression ratio and the temporal length of that portion of each compressed re-formatted video line containing said groups being less than said overall temporal length and greater than said active signal portion temporal length, said method comprising the steps of:

(a) providing said SECAL video type signals;

(b) generating a first clock signal having a first frequency;

(c) sampling said SECAL video type signals with said first clock signal;

(d) temporarily storing the SECAL samples in a storage device;

(e) generating second and third clock signals having second and third frequencies, the ratio of said second and third frequencies being equal to said predetermined compression ratio and said first frequency being higher than said second frequency;

(f) sequentially reading the SECAL luminance group samples corresponding to a given line from said storage device with said second clock signals while contemporaneously sequentially reading the SECAL chrominance group samples corresponding to the same line from said storage device with said third clock signals; and

(g) assembling the contemporaneously read SECAL luminance and chrominance samples into said composite video signals, the relative number of luminance samples and chrominance samples produced by said first clock signal and the frequency of said second and third clock signals being selected so that the temporal length of the portion of each line of composite video signals assembled from said SECAL luminance and chrominance samples is substantially equal to the temporal length of said active portion.

21. The method of claim 20 wherein said step (b) of generating includes the step of synchronizing said first clock signal with a video line reference pulse contained in said compressed video lines.

22. The method of claim 21 wherein said video line reference pulse comprises a modified horizontal sync pulse of reduced width from a standard horizontal sync pulse.

23. The method of claim 20 wherein the samples in one of said groups are digital and wherein said step of temporarily storing includes the steps of storing said one of said pair of groups of samples in a digital storage device and storing the other one of said group of samples in an analog storage device.

24. The method of claim 20 wherein said step of storing includes the step of storing said pair of groups in an analog storage device.

25. The method of claim 20 wherein said samples are digital and wherein said step of storing includes the step of storing said pair of groups in a digital memory.

26. The method of claim 20 wherein said step (g) of assembling includes the steps of generating conventional composite sync blanking and burst signals, and inserting said composite sync, blanking and burst signals at the beginning of each line of composite video.

27. The method of claim 26 further including the step of providing a studio sync generator, and wherein said step of generating is performed in synchronism with said studio sync generator.

28. The method of claim 20 wherein said compressed video lines include a color reference level signal and wherein said step (g) of assembling includes the step of using said color reference level signal to adjust the magnitude of said chrominance samples.

29. The method of claim 28 wherein said color reference level signal is located between said luminance samples and said chrominance samples.

30. The method of claim 20 wherein said compressed signals are recorded on a recording medium, and wherein said step (a) of providing includes the step of reproducing said signals from said recording medium.

31. The method of claim 20 wherein said step (a) of providing includes the step of transmitting said compressed signals from a transmitting station to a receiving station over a communication link having said reduced bandwidth.

32. A system for re-formatting video type line sequential signals having luminance components and chrominance components, each line of said line sequential signals having a predetermined overall temporal length and an active signal portion of predetermined temporal length less than the overall length, said system comprising:

input terminal means for receiving said luminance components and said chrominance components;

means for generating first and second clock signals having frequencies f and f/N, respectively, where N is a finite non-zero value;

means coupled to said input terminal means and said generating means for sampling and storing said luminance components and said chrominance components with said first and second sampling clock signals, respectively;

means for generating a third clock signal having a frequency higher than said first clock signal frequency; and

means coupled to said sampling means and said third clock signal generating means for serially arranging the sampled and stored component samples on a line-by-line basis to form compressed re-formatted video lines each containing a pair of groups of samples, one of said pair of groups containing luminance samples, the other of said pair of groups containing chrominance samples, said groups being compressed in accordance with a predetermined ratio equal to said value N, said arranging means including means for first reading one of said pair of groups of samples from said sampling and storing means with said third clock signals and then reading the other one of said pair of groups of samples from said sampling and storing means with said third clock signals, the relative number of luminance samples and chrominance samples and the frequency of said third clock signals being selected so that the temporal length of each compressed re-formatted video line is less than said overall temporal length and greater than said active signal portion temporal length.

33. The system of claim 32 further including means having an output coupled to said input terminal means for separating said video type signals into said luminance components and said chrominance components.

34. The system of claim 32 wherein N is an integer.

35. The system of claim 32 wherein said sampling and storing means further includes means for synchronizing said clock signals with a video line reference pulse.

36. The system of claim 35 wherein said line reference pulse comprises the horizontal sync pulse.

37. The system of claim 35 wherein said sampling and storing means includes means for forming digital samples of one of said groups, a digital storage device for storing said digital samples and an analog storage device for storing the remaining samples.

38. The system of claim 32 wherein said sampling and storing means comprises an analog storage device.

39. The system of claim 32 wherein said sampling and storing means includes means for forming digital samples, and a digital memory device for storing said digital samples.

40. The system of claim 32 wherein said sampling and storing means includes means for forming digital samples, and further including means having an input coupled to the output of said reading means for converting each re-formatted video line from digital to analog form.

41. The system of claim 40 further including means for recording the analog video lines on a recording medium.

42. The system of claim 40 further including means for transmitting the analog video lines to a receiving station.

43. The system of claim 32 wherein said video type signals include an original video line reference pulse, and further including means for generating a modified video line reference pulse of reduced width from said original line reference pulse, and means for inserting said modified video line reference pulse in each of said re-formatted video lines.

44. The system of claim 43 wherein said original line reference pulse comprises a horizontal sync pulse of conventional time duration.

45. The system of claim 32 wherein said video type signals include two color difference components per line, and wherein said means for serially arranging includes means for including samples in said other pair of groups corresponding to both said color difference components.

46. The system of claim 32 wherein said video type signals include alternate color difference components in alternate video lines and wherein said means for serially arranging includes means for including samples in said other pair of groups corresponding to one of said color difference components for a first set of re-formatted video lines, and means for including samples in said other pair of groups corresponding to the other one of said color difference components for a second set of re-formatted lines.

47. The system of claim 32 wherein said means for serially arranging further includes means for generating a color reference mezzanine signal, and means for inserting said mezzanine signal into said re-formatted video line at a predetermined line location.

48. The system of claim 47 wherein said inserting means includes means for positioning said mezzanine signal between said two groups.

49. The system of claim 32 wherein said means for serially arranging includes means for re-formatting each of said video lines to contain a group of luminance samples followed by a group of chrominance samples.

50. The system of claim 32 wherein said means for serially arranging includes means for re-formatting each of said video lines to contain a group of chrominance samples followed by a group of luminance samples.

51. A system for processing sequentially encoded color and luminance (SECAL) video type signals corresponding to original standard composite video signals having a predetermined overall temporal length and an active signal portion of predetermined temporal length less than the overall length, said SECAL video type signals having luminance and chrominance components re-formatted as compressed video lines of reduced bandwidth, each line containing a pair of contiguous groups of video signals, one of said pair of groups containing compressed luminance samples, the other of said pair of groups containing compressed chrominance samples, said groups being compressed in accordance with a predetermined compression ratio and the temporal length of that portion of each compressed re-formatted video line containing said groups being less than said overall temporal length and greater than said active signal portion temporal length, said system comprising:

input terminal means for receiving said re-formatted video type signals;

means for generating a first clock signal having a first frequency;

means coupled to said input terminal means and said generating means for sampling and storing said re-formatted lines with said first clock signals;

means for generating second and third clock signals having second and third frequencies, the ratio of said second and third frequencies being equal to said predetermined compression ratio and said first frequency being higher than said second frequency; and

means for converting the sampled groups to successive lines of standard composite video signals, said converting means including means for sequentially reading the SECAL luminance group samples corresponding to a given line from said sampling and storing means with said second clock signals while contemporaneously sequentially reading the SECAL chrominance group samples corresponding to the same line from said sampling and storing means with said third clock signals; and

means for assembling the contemporaneously read SECAL luminance and chrominance samples into said composite video signals, the relative number of luminance samples and chrominance samples produced by said first clock signal and the frequency of said second and third clock signals being selected so that the temporal length of the portion of each line of composite video signals assembled from said SECAL luminance and chrominance samples is substantially equal to the temporal length of said active portion.

52. The system of claim 51 wherein said sampling and storing means includes means for synchronizing said first clock signal with a video line reference pulse contained in said re-formatted line.

53. The system of claim 52 wherein said video line reference pulse comprises a modified horizontal sync pulse of reduced width from a standard horizontal zync pulse.

54. The system of claim 51 wherein said sampling and storing means includes means for forming digital samples of one of said pair of groups, a digital storage device for storing said one of said pair of groups of samples and an analog storage device for storing the other one of said group of samples.

55. The system of claim 51 wherein said storage device comprises an analog storage device.

56. The system of claim 51 wherein said sampling and storing means includes means for forming digital samples, and a digital memory means for storing said digital samples.

57. The system of claim 51 wherein said converting means includes means for generating conventional composite sync, blanking and burst signals, and means for inserting said composite sync, blanking and burst signals at the beginning of each line of composite video.

58. The system of claim 56 wherein said composite sync, blanking and burst signal generating means comprises a studio sync generator means.

59. The system of claim 51 wherein said reformatted composite video lines include a color reference level signal, at a predetermined line location, and wherein said converting means includes means for adjusting the magnitude of said chrominance components in accordance with said color reference level signal.

60. The system of claim 51 wherein said color reference level is positioned between said two groups.

61. The system of claim 51 wherein said re-formatted signals are recorded on a recording medium, and wherein said system further includes means coupled to said input terminal means for reproduding said signals from said recording medium.

62. The system of claim 51 wherein said re-formatted signals are transmitted from a transmitting station and wherein said input terminal means includes means for receiving said transmitted signals.

63. A method for processing video type line sequential signals having luminance components and chrominance components to reduce the bandwidth thereof, each line of said line sequential signals having a predetermined overall temporal length and an active signal portion of predetermined temporal length less than said overall length, said method comprising the steps of:

(a) generating first and second sampling clock signals having frequencies f and f/N, respectively, where N is a finite non-zero value;

(b) sampling said luminance and said chrominance components with said first and second clock signals, respectively;

(c) temporarily storing the component samples in a storage device;

(d) generating a third clock signal having a frequency higher than said first clock signal frequency;

(e) serially arranging the temporarily stored component samples on a line-by-line basis to form compressed re-formatted sequentially encoded color and luminance (SECAL) video lines each containing a pair of groups of samples, one of said pair of groups containing luminance samples, the other of said pair of groups containing chrominance samples, said groups being compressed in accordance with a predetermined ratio equal to said value N, said step of serially arranging including the step of first outputting one of said pair of groups of samples under control of said third clock signal and then outputting the other one of said pair of groups of samples under control of said third clock signal, the relative number of luminance samples and chrominance samples and the frequency of said third clock signal being selected so that the temporal length of that portion of each compressed re-formatted video line containing said groups is less than said overall temporal length and greater than said active signal portion temporal length;

(f) providing said re-formatted SECAL video line signals to a subsequent processing device;

(g) generating a fourth clock signal having a fourth frequency;

(h) sampling said SECAL video type signals with said fourth clock signal;

(i) temporarily storing the SECAL samples in a storage device;

(j) generating fifth and sixth clock signals having fifth and sixth frequencies, the ratio of said fifth and sixth frequencies being equal to N and said fourth frequency being higher than said fifth frequency;

(k) sequentially reading the SECAL luminance group samples corresponding to a given line from said storage device with said fifth clock signals while contemporaneously sequentially reading the SECAL chrominance group samples corresponding to the same line from said storage device with said sixth clock signals; and

(l) reassembling the contemporaneously read SECAL luminance and chrominance samples into the original composite video signal format, the relative number of luminance samples and chrominance samples produced by said fourth clock signal and the frequency of said fifth and sixth clock signals being selected so that the temporal length of the portion of each line of composite video signals reassembled from said SECAL luminance and chrominance samples is substantially equal to the temporal length of said active portion of the original composite video signals.

64. The method of claim 63 wherein said step (b) of sampling is preceded by the step of separating said chrominance components from said luminance components.

65. The method of claim 63 wherein said samples are digital, and wherein said step (f) of providing includes the steps of converting each re-formatted video line to analog form, and recording the analog video lines on a recording medium.

66. The method of claim 65 wherein said step (f) of providing further includes the step of reproducing said signals from said recording medium.

67. The method of claim 63 wherein said samples are digital and wherein said step (f) of providing further includes the steps of converting each re-formatted line to analog form, and transmitting the analog video lines to a receiving station.

68. Apparatus for recording video signals comprising:

means for receiving video signals having a line scan format that includes, in serial form, a timing signal, a color reference signal, and a superimposed luminance and chrominance signal, each signal occupying a predetermined portion of each line;

means for modifying said video signals into a line scan format having a time duration that is a function of the duration of each line of said received signals and including in serial form, a timing signal, a separate luminance signal, and a separate chrominance signal, wherein the time duration of each modified line is substantially equal to the time duration of each line of the received signals, the combined time duration of the luminance and chrominance signals of each modified line is greater than the time duration of the superimposed luminance and chrominance signals and less than the time duration of each line of the received signals, and the time duration of the luminance signal of each modified line is less than the time duration of the superimposed luminance and chrominance signals, and

means for recording said modified video signals.

69. Apparatus as defined in claim 68 including:

means for reproducing the recorded modified video signals, and

means for modifying the reproduced video signals to have a line scan format corresponding to that of the received video signals.

70. Apparatus as defined in claim 68 wherein the combined time duration of said separate luminance and chrominance signals of each modified line is at least equal to the combined time duration of the portion of the received signal including the color reference signal and the superimposed luminance and chrominance signals.

71. Apparatus as defined in claim 68 wherein said modifying means includes means for establishing the relative time duration of the separate luminance and chrominance signals as a preset ratio.

72. Apparatus as defined in claim 71 wherein said establishing means includes means for maintaining the time duration of the separate luminance signal substantially greater than that of the separate chrominance signal.

73. Apparatus as defined in claim 68 wherein said modifying means includes means for separating the superimposed luminance and chrominance signal into said separate luminance and chrominance signals, means for separating the chrominance signal into a plurality of color information signals, and means for including the plurality of color information signals in said serial format as said separate chrominance signal.

74. Apparatus as defined in claim 73 wherein said including means comprises means for providing all of said plurality of color information signals in each line scan format of each of said modified video signals.

75. Apparatus as defined in claim 68 wherein said modifying means includes means for deparating the superimposed luminance and chrominance signal into said separate luminance and chrominance signals, means for separating said chrominance signal into a plurality of color information signals, and means for including one of said plurality of color information signals in any single line scan.