Block noise detector and block noise eliminator

• US 6,738,528 B1
• Filed: 01/21/2000
• Issued: 05/18/2004
• Est. Priority Date: 05/22/1998
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Tanaka, Kazuhito, Okamoto, Satoshi, Terai, Katsumi, Nio, Yutaka, Okumura, Naoji
• Primary Examiner(s): MARIAM, DANIEL G
• Application Number:
  US09/463,215
• Time in Patent Office: 1,579 Days
• Field of Search: 382/173, 382/232-233, 382/250-251, 382/261, 382/263, 382/264, 382/266, 382/268-269, 382/275, 348/384.1, 348/390.1, 348/398.1, 348/400.1, 348/425.2, 358/426.04, 358/426.14, 375/240.11, 375/241, 375/243
• US Class Current: 382/268
• CPC Class Codes: H04N 19/527 Global motion vector estimation
• CPC Class Codes: H04N 19/80 Details of filtering operations specially adapted for video compression, e.g. for pixel interpolation H04N19/635, H04N19/86 take precedence
• CPC Class Codes: H04N 19/86 involving reduction of coding artifacts, e.g. of blockiness
• CPC Class Codes: H04N 19/865 with detection of the former encoding block subdivision in decompressed video

Abstract

A vertical HPF and a horizontal HPF receive a video signal 101, and extract only a high frequency component in the vertical/horizontal directions, respectively. Absolute value taking parts take an absolute value of the high frequency components, respectively, and change their values to positive values. A horizontal accumulating/adding part and a vertical accumulating/adding part accumulate/add an input signal so as to output a vertical one-dimensional signal and a horizontal one-dimensional signal, respectively, each periodically having a peak value in the respective vertical and horizontal directions. A horizontal peak detecting part detects a horizontal peak position according to the horizontal one-dimensional signal. A vertical peak detecting part detects a vertical peak position according to the vertical one-dimensional signal and identifies a format thereof. A binarization part obtains a block boundary image, according to the horizontal peak position and the vertical peak position, in which pixel positions having a peak are provided with 1 and remaining pixel positions are provided with 0. In this manner, even if a block boundary to eliminate block noise thereon is not clearly identified, it becomes possible to correctly detect and eliminate the block boundary.

Claims

1. A block noise detecting apparatus for detecting, from a digital video signal subjected to lossy encoding on a predetermined image block basis, block noise caused by decoding the video signal, said block noise detecting the apparatus comprising:

signal extracting means for receiving the video signal and extracting a high frequency component from the video signal;

absolute value taking means for taking an absolute value of a high frequency component signal outputted from said signal extracting means;

accumulating/adding means for accumulating/adding an absolute value signal outputted from said absolute value taking means for a predetermined period;

periodicity detecting means for detecting periodicity of the block noise in accordance with an accumulation/addition result outputted from said accumulating/adding means; and

block boundary determining means for determining a block boundary, where the block noise is generated, from a periodic signal detected by said periodicity detecting means.

2. The block noise detecting apparatus according to claim 1, wherein said block boundary determining means distinguishes, with binary values, between positional information on the block boundary and positional information on a remainder of an image.

3. The block noise detecting apparatus according to claim 2, further comprising:

frame difference taking means for receiving the video signal and determining a signal difference among a plurality of predetermined frames of the video signal;

region determining means for determining, with reference to whether or not the signal difference outputted from said frame difference taking means is greater than a predetermined threshold value, a noise region where the block noise to be eliminated is observed; and

block edge controlling means for masking the block boundary determined by said block boundary determining means in the noise region determined by said region determining means, and then determining a portion of the block boundary corresponding to the noise region.

4. The block noise detecting apparatus according to claim 2;

wherein said signal extracting means, said absolute value taking means, said accumulating/adding means, and said periodicity detecting means each execute processing for the video signal in at least one of a horizontal direction and a vertical direction.

5. The block noise detecting apparatus according to claim 1, further comprising:

frame difference taking means for receiving the video signal and determining a signal difference among a plurality of predetermined frames of the video signal;

region determining means for determining, with reference to whether or not the signal difference outputted from said frame difference taking means is greater than a predetermined threshold value, a noise region where the block noise to be eliminated is observed; and

block edge controlling means for masking the block boundary determined by said block boundary determining means in the noise region determined by said region determining means, and then determining a portion of the block boundary corresponding to the noise region.

6. The block noise detecting apparatus according to claim 5, wherein said frame difference taking means determines a signal difference between a current frame and a previous frame.

7. The block noise detecting apparatus according to claim 6 wherein said region determining means distinguishes, with binary values, between a part of the signal difference exceeding the threshold value and a part of the signal difference not exceeding the threshold value.

8. The block noise detecting apparatus according to claim 6, further comprising singular point eliminating means for excluding a noise part observed in a predetermined small region of the noise region determined by said region determining means, wherein

said block edge controlling means masks the block boundary determined by the block boundary determining means in the noise region excluding the noise part outputted from said singular point eliminating means.

9. The block noise detecting apparatus according to claim 6, wherein said signal extracting means, said absolute value taking means, said accumulating/adding means, and said periodicity detecting means each execute processing for the video signal in at least one of a horizontal direction and a vertical direction.

10. The block noise detecting apparatus according to claim 5, wherein said region determining means distinguishes, with binary values, between a part of the signal difference exceeding the threshold value and a part of the signal difference not exceeding the threshold value.

11. The block noise detecting apparatus according to claim 10, further comprising singular point eliminating means for excluding a noise part observed in a predetermined small region of the noise region determined by said region determining means, wherein

said block edge controlling means masks the block boundary determined by said block boundary determining means in the noise region excluding the noise part outputted from said singular point eliminating means.

12. The block noise detecting apparatus according to claim 10, wherein said signal extracting means, said absolute value taking means, said accumulating/adding means, and said periodicity detecting means each execute processing for the video signal in at least one of a horizontal direction and a vertical direction.

13. The block noise detecting apparatus according to claim 5, further comprising singular point eliminating means for excluding a noise part observed in a predetermined small region of the noise region determined by said region determining means, wherein

said block edge controlling means masks the block boundary determined by said block boundary determining means in the noise region excluding the noise part outputted from said singular point eliminating means.

14. The block noise detecting apparatus according to claim 13, wherein said signal extracting means, said absolute value taking means, said accumulating/adding means, and said periodicity detecting means each execute processing for said the video signal in at least one of a horizontal direction and a vertical direction.

15. The block noise detecting apparatus according to claim 5, wherein said signal extracting means, said absolute value taking means, said accumulating/adding means, and said periodicity detecting means each execute processing for the video signal in at least one of a horizontal direction and a vertical direction.

16. The block noise detecting apparatus according to claim 1, wherein said signal extracting means, said absolute value taking means, said accumulating/adding means, and said periodicity detecting means each execute processing for the sad video signal in at least one of a horizontal directional and a vertical direction.

17. The block noise detecting apparatus according to claim 16, wherein,

when each of the processing is executed for the video signal in the vertical direction,

said periodicity detecting means successively changes frames of the video signal used for detection according to a format of the video signal to be inputted.

18. A block noise eliminating apparatus for detecting and eliminating, from a digital video signal subjected to lossy encoding on a predetermined image block basis, block noise caused by decoding the video signal, said block noise elimination apparatus comprising:

signal extracting means for receiving the video signal and extracting only a high frequency component from the video signal;

absolute value taking means for taking an absolute value of a high frequency component signal outputted from said signal extracting means;

accumulating/adding means for accumulating/adding an absolute value signal outputted from said absolute value taking means for a predetermined period;

periodicity detecting means for detecting periodicity of the block noise in accordance with an accumulation/addition result outputted from said accumulating/adding means;

block boundary determining means for determining a block boundary, where the block noise is generated, from a periodic signal detected by said periodicity detecting means; and

block noise eliminating means for eliminating the block noise with respect to the block boundary.

19. The block noise eliminating apparatus according to claim 18, wherein said block boundary determining means distinguishes, with binary values, between positional information on the block boundary and positional information on a remainder of an image.

20. The block noise eliminating apparatus according to claim 19, further comprising:

frame difference taking means for receiving the video signal and determining a signal difference among a plurality of predetermined frames of the video signal;

region determining means for determining, with reference to whether or not the signal difference outputted from said frame difference taking means is greater than a predetermined threshold value, a noise region where the block noise to be eliminated is observed; and

block edge controlling means for masking the block boundary determined by said block boundary determining means in the noise region determined by said region determining means, and then determining a portion of the block boundary corresponding to the noise region, wherein

said block noise eliminating means eliminates the block noise with respect to the portion of the block boundary corresponding to the noise region.

21. The block noise eliminating apparatus according to claim 19, wherein said signal extracting means, said absolute value taking means, said accumulating/adding means, and said periodicity detecting means each execute processing for the video signal in at least one of a horizontal direction and a vertical direction.

22. The block noise eliminating apparatus according to claim 18, further comprising:

frame difference taking means for receiving the video signal and determining a signal difference among a plurality of predetermined frames of the video signal;

region determining means for determining, with reference to whether or not the signal difference outputted from said frame difference taking means is greater than a predetermined threshold value, a noise region where the block noise to be eliminated is observed; and

block edge controlling means for masking the block boundary determined by said block boundary determining means in the noise region determined by said region determining means, and then determining a portion of the block boundary corresponding to the noise region, wherein

said block noise eliminating means eliminates the block noise with respect to the portion of the block boundary corresponding to the noise region.

23. The block noise eliminating apparatus according to claim 22, wherein said frame difference taking means determines the signal difference between a current frame and a previous frame.

24. The block noise eliminating apparatus according to claim 23, wherein said region determining means distinguishes, with binary values, between a part of the signal difference exceeding the threshold value and a part of the signal difference not exceeding the threshold value.

25. The block noise eliminating means according to claim 23, further comprising singular point eliminating means for excluding a noise part observed in a predetermined small region of the noise region determined by said region determining means, wherein

said block edge controlling means masks the block boundary determined by said block boundary determining means in the noise region excluding the noise part outputted from said singular point eliminating means.

26. The block noise eliminating apparatus according to claim 23, wherein said signal extracting means, said absolute value taking means, said accumulating/adding means, and said periodicity detecting means each execute processing for the video signal in at least one of a horizontal direction and a vertical direction.

27. The block noise eliminating apparatus according to claim 22, wherein said region determining means distinguishes, with binary values, between a part of the signal difference exceeding the threshold value and a part of the signal difference not exceeding the threshold value.

28. The block noise eliminating means according to claim 27, further comprising singular point eliminating means for excluding a noise part observed in a predetermined small region of the noise region determined by said region determining means, wherein

said block edge controlling means masks the block boundary determined by said block boundary determining means in the noise region excluding the noise part outputted from said singular point eliminating means.

29. The block noise eliminating apparatus according to claim 27, wherein said signal extracting means, said absolute value taking means, said accumulating/adding means, and said periodicity detecting means each execute processing for the video signal in at least one of a horizontal direction and a vertical direction.

30. The block noise eliminating means according to claim 22, further comprising singular point eliminating means for excluding a noise part observed in a predetermined small region of the noise region determined by said region determining means, wherein

said block edge controlling means masks the block boundary determined by said block boundary determining means in the noise region excluding the noise part outputted from said singular point eliminating means.

31. The block noise eliminating apparatus according to claim 30, wherein said signal extracting means, said absolute value taking means, said accumulating/adding means, and said periodicity detecting means each execute processing for the video signal in at least one of a horizontal direction and a vertical direction.

32. The block noise eliminating apparatus according to claim 22, wherein said signal extracting means, said absolute value taking means, said accumulating/adding means, and said periodicity detecting means each execute processing for the video signal in at least one of a horizontal direction and a vertical direction.

33. The block noise eliminating apparatus according to claim 18, wherein said signal extracting means, said absolute value taking means part, said accumulating/adding means, and said periodicity detecting means each execute processing for the video signal in at least one of a horizontal direction and a vertical direction.

34. The block noise eliminating apparatus according to claim 33, further comprising identifying means for identifying a format of the video signal to be inputted, wherein

when each of the processing is executed for the video signal in the vertical direction,

said identifying means has said periodicity detecting means successively change frames of the video signal used for detection according to the format.

35. A block noise eliminating apparatus for detecting and eliminating, from a digital video signal subjected to lossy encoding on a predetermined image block basis, block noise caused by decoding the video signal, said block noise eliminating apparatus comprising:

vertical block boundary detecting means for receiving the video signal and detecting with respect to the video signal, a vertical block boundary where the block noise is generated, in a lateral direction and a vertical block noise level on a screen;

horizontal block boundary detecting means for receiving the video signal and detecting, with respect to the video signal, a horizontal block boundary, where the block noise is generated, in a longitudinal direction and a horizontal block noise level on the screen;

block area detecting means for specifying a block boundary in both the longitudinal direction and the lateral direction from the vertical block boundary and the horizontal block boundary detected in said vertical block boundary detecting means and said horizontal block boundary detecting means, respectively; and

block boundary smoothing means for smoothing the video signal to be inputted in a predetermined manner corresponding to the block boundary in both the longitudinal direction and the lateral direction specified by said block area detecting means,

wherein said vertical block boundary detecting means comprises;

a vertical high-pass filter for extracting a vertical high frequency component of the video signal;

first absolute value taking means for taking an absolute value of a high frequency component signal outputted from said vertical high-pass filter;

horizontal accumulating/adding means for accumulating/adding an absolute value signal outputted from said first absolute value taking means in a horizontal direction;

a first high-pass filter for extracting a high frequency component from an accumulated/added high frequency component signal outputted from said horizontal accumulating/adding means;

first N-point accumulating/adding means for accumulating/adding a signal outputted from said first high-pass filter on a predetermined N-point basis, where N is a positive integer;

a first temporal filter for detecting the vertical block noise level of the video signal by extending the signal outputted from said first high-pass filter in a temporal direction;

first maximum value detecting means for determining a maximum value and a position of the maximum value from among N-piece accumulated/added values determined by said first N-point accumulating/adding means through accumulation/addition; and

first masking means for masking the vertical block noise level detected by said first temporal filter at the position of the maximum value outputted from said first maximum value detecting means, and then determining the vertical block boundary corresponding to the position, and wherein

said horizontal block boundary detecting means comprises;

a horizontal high-pass filter for extracting a horizontal high frequency component of the video signal;

second absolute value taking means for taking an absolute value of a high frequency component signal outputted from said horizontal high-pass filter;

vertical accumulating/adding means for accumulating/adding an absolute value signal outputted from said second absolute value taking means in a vertical direction;

a second high-pass filter for extracting a high frequency component from an accumulated/added high frequency component signal outputted from said vertical accumulating/adding means;

second N-point accumulating/adding means for accumulating/adding a signal outputted from said second high-pass filter on a predetermined N-point basis;

a second temporal filter for detecting the horizontal block noise level of the video signal by extending the signal outputted from said second high-pass filter in a temporal direction;

second maximum value detecting means for determining a maximum value and a position of the maximum value from among N-piece accumulated/added values determined by said second N-point accumulating/adding means through accumulation/addition; and

second masking means for masking the horizontal block noise level detected by said second temporal filter at the position of the maximum value outputted from said second maximum value detecting means, and then determining the horizontal block boundary corresponding to the position.

36. The block noise eliminating apparatus according to claim 35, wherein said block boundary smoothing means comprises:

a horizontal high-pass filter for extracting a horizontal high frequency component of the video signal;

first multiplying means for multiplying an output of said horizontal high-pass filter and an output of said horizontal block boundary detecting means;

first deducting means for deducting an output of said first multiplying means from the video signal;

a vertical high-pass filter for extracting a vertical high frequency component of the video signal;

second multiplying means for multiplying an output of said vertical high-pass filter and an output of said vertical block boundary detecting means; and

second deducting means for deducting an output of said second multiplying means from the video signal, wherein

the block noise is eliminated according to the horizontal and vertical block noise levels.

37. The block noise eliminating apparatus according to claim 36, further comprising picture enhancing means for controlling a picture enhancement level emphasizing an outline part of the video signal according to the horizontal block noise level detected by said horizontal block boundary detecting means and the vertical block noise level detected by said vertical block boundary detecting means.

38. The block noise eliminating apparatus according to claim 36, further comprising controlling means for specifying the video signal to be inputted in accordance with the horizontal block noise level detected by said horizontal block boundary detecting means and the vertical block noise level detected by said vertical block boundary detecting means, wherein

said controlling means is operable to display a judgement result of the specification of the video signal on a screen in a predetermined format.

39. The block noise eliminating apparatus according to claim 35, further comprising picture enhancing means for controlling a picture enhancement level emphasizing an outline part of the video signal according to the horizontal block noise level detected by said horizontal block boundary detecting means and the vertical block noise level detected by vertical block boundary detecting means.

40. The block noise eliminating apparatus according to claim 35, further comprising controlling means for specifying the video signal to be inputted in accordance with the horizontal block noise level detected by said horizontal block boundary detecting means and the vertical block noise level detected by said vertical block boundary detecting means, wherein

said controlling means is operable to display a judgement result of the specification of the video signal on a screen in a predetermined format.

41. A block noise eliminating apparatus for detecting and eliminating, from a video signal subjected to lossy encoding on a predetermined image block basis, block noise caused by decoding the video signal, said block noise eliminating apparatus comprising:

AD converting means for receiving an analog video signal and then converting the analog video signal into a first digital video signal;

digital decoding means for receiving a second digital video signal as an encoded digital signal and for decoding and outputting the second video signal including decoded block boundary information;

a selector for receiving the first digital video signal outputted from said AD converting means and the second digital video signal outputted from said digital decoding means and selectively outputting one of the first and second digital video signals, as the video signal, as is externally instructed;

vertical block boundary detecting means for receiving the video signal selected by said selector and detecting, with respect to the video signal, a vertical block boundary, where the block noise is generated, in a lateral direction and a vertical block noise level on a screen;

horizontal block boundary detecting means for receiving the video signal selected by said selector and detecting, with respect to the video signal, a horizontal block boundary, where the block noise is generated in a longitudinal direction and a horizontal block noise level on a the screen;

block area detecting means for specifying a block boundary in both the longitudinal direction and the lateral direction from the vertical block boundary and the horizontal block boundary detected in said vertical block boundary detecting means and said horizontal block boundary detecting means respectively; and

block boundary smoothing means for smoothing the video signal in a predetermined manner corresponding to the block boundary in both the longitudinal direction and the lateral direction specified by said block area detecting means, wherein

said vertical block boundary detecting means and said horizontal block boundary detecting means output, to said block area detecting means, the vertical block boundary and the horizontal block boundary, respectively, when said selector selects the first video signal outputted from said AD converting means, and output a block boundary based on the block boundary information outputted from said digital decoding means when said selector selects the second video signal outputted from said digital decoding means.

42. The block noise eliminating apparatus according to claim 41, wherein said vertical block boundary detecting means comprises:

a vertical high-pass filter for extracting a vertical high frequency component of the video signal;

first absolute value taking means for taking an absolute value of a high frequency component signal outputted from said vertical high-pass filter;

horizontal accumulating/adding means for accumulating/adding an absolute value signal outputted from said first absolute value taking means in a horizontal direction;

a first high-pass filter for extracting a high frequency component from an accumulated/added high frequency component signal outputted from said horizontal accumulating/adding means;

first N-point accumulating/adding means for accumulating/adding a signal outputted from said first high-pass filter on a predetermined N-point basis, where N is a positive integer;

a first temporal filter for detecting the vertical block noise level of the selected video signal by extending the signal outputted from said first high-pass filter in a temporal direction;

first maximum value detecting means for determining a maximum value and a position of the maximum value among N-piece accumulated/added values determined by said first N-point accumulating/adding means through accumulation/addition;

a first selector for synchronizing with the video signal and selectively outputting either one of the block boundary information outputted from said digital decoding means or the position of the maximum value outputted from said first maximum value detecting means, as a first selected output; and

first masking means for masking the vertical block noise level detected by said first temporal filter at the first selected output from said first selector, and determining the vertical block boundary corresponding to the position, and wherein

said horizontal block boundary detecting means comprises;

a horizontal high-pass filter for extracting a horizontal high frequency component of the video signal;

second absolute value taking means for taking an absolute value of a high frequency component signal outputted from said horizontal high-pass filter;

vertical accumulating/adding means for accumulating/adding an absolute value signal outputted from said second absolute value taking means in a vertical direction;

a second high-pass filter for extracting a high frequency component from an accumulated/added high frequency component signal outputted from said vertical accumulating/adding means;

second N-point accumulating/adding means for accumulating/adding a signal outputted from said second high-pass filter on a predetermined N-point basis;

a second temporal filter for detecting the horizontal block noise level of the video signal by extending the signal outputted from said second high-pass filter in a temporal direction;

second maximum value detecting means for determining a maximum value and a position of the maximum value among N-piece accumulated/added values determined by said second N-point accumulating/adding means through accumulation/addition;

a second selector for synchronizing with the video signal and selectively outputting either one of the block boundary information outputted from said digital decoding means or the position of the maximum value outputted from said second maximum value detecting means, as a second selected output; and

second masking means for masking the horizontal block noise level detected by said second temporal filter at the second selected output from said second selector, and determining the horizontal block boundary corresponding to the position.

43. The block noise eliminating apparatus according to claim 42, wherein said block boundary smoothing means comprises:

a horizontal high-pass filter for extracting a horizontal high frequency component of the video signal;

first multiplying means for multiplying an output of said horizontal high-pass filter and an output of said horizontal block boundary detecting means;

first deducting means for deducting an output of said first multiplying means from the video signal;

a vertical high-pass filter for extracting only a vertical high frequency component of the video signal;

second multiplying means for multiplying an output of said vertical high-pass filter and an output of said vertical block boundary detecting means; and

second deducting means for deducting an output of the second multiplying means from the video signal, wherein

the block noise is eliminated according to the block noise level.

44. The block noise eliminating apparatus according to claim 42, further comprising picture enhancing means for controlling a picture enhancement level emphasizing an outline part of the video signal according to the horizontal block noise level detected by said horizontal block boundary detecting means and the vertical block noise level detected by said vertical block boundary detecting means.

45. The block noise eliminating apparatus according to claim 42, further comprising controlling means for specifying the video signal to be inputted in accordance with the horizontal block noise level detected by said horizontal block boundary detecting means and the vertical block noise level detected by said vertical block boundary detecting means, wherein

said controlling means is operable to display a judgement result of the specification of the video signal on a screen in a predetermined format.

46. The block noise eliminating apparatus according to claim 41, further comprising picture enhancing means for controlling a picture enhancement level emphasizing an outline part of the video signal according to the horizontal block noise level detected by said horizontal block boundary detecting means and the vertical block noise level detected by said vertical block boundary detecting means.

47. The block noise eliminating apparatus according to claim 41, further comprising controlling means for specifying the video signal to be inputted in accordance with the horizontal block noise level detected by said horizontal block boundary detecting means and the vertical block noise level detected by said vertical block boundary detecting means, wherein

said controlling means is operable to display a judgement result of the specification of the video signal on a screen in a predetermined format.

48. A block noise eliminating apparatus for detecting and eliminating, from a digital video signal subjected to lossy encoding on a predetermined image block basis, block noise caused by decoding the video signal said block noise eliminating apparatus comprising:

vertical block boundary detecting means for receiving the video signal and detecting, with respect to the video signal, a vertical block boundary, where the block noise is generated, in a lateral direction and a vertical block noise level on a screen;

horizontal block boundary detecting means for receiving the video signal and detecting, with respect to the video signal, a horizontal block boundary, where the block noise is generated, in a longitudinal direction and a horizontal block noise level on the screen;

block area detecting means for specifying a block boundary in both the longitudinal direction and the lateral direction from the vertical block boundary and the horizontal block boundary detected in said vertical block boundary detecting means and said horizontal block boundary detecting means, respectively;

block boundary smoothing means for smoothing the video signal to be inputted in a predetermined manner corresponding to the block boundary in both the longitudinal direction and the lateral direction specified by said block area detecting means; and

controlling means for specifying the video signal to be inputted in accordance with the horizontal block noise level detected by said horizontal block boundary detecting means and the vertical block noise level detected by said vertical block boundary detecting means, wherein

said controlling means is operable to display a judgement result of the specification of the video signal on a screen in a predetermined format.

49. A vertical block boundary detecting apparatus for detecting, from a digital video signal subjected to lossy encoding on a predetermined image block basis, block noise in a vertical direction caused by decoding the video signal, said vertical block boundary detecting apparatus comprising:

a vertical high-pass filter for receiving the video signal and extracting a vertical high frequency component of the video signal;

absolute value taking means for taking an absolute value of a high frequency component signal outputted from said vertical high-pass filter;

horizontal accumulating/adding means for accumulating/adding an absolute value signal outputted from said absolute value taking means in a horizontal direction;

a high-pass filter for extracting a high frequency component from an accumulated/added high frequency component signal outputted from said horizontal accumulating/adding means;

N-point accumulating/adding means for accumulating/adding a signal outputted from said high-pass filter on a predetermined N-point basis, where N is a positive integer;

a temporal filter for detecting a block noise level of the video signal by extending the signal outputted from said high-pass filter in a temporal direction;

maximum value detecting means for determining a maximum value and a position of the maximum value among N-piece accumulated/added values determined by said N-point accumulating/adding means through accumulation/addition; and

masking means for masking the block noise level detected by said temporal filter at the position of the maximum value outputted from said maximum value detecting means, and determining a vertical block boundary corresponding to the position.

50. A horizontal block boundary detecting apparatus for detecting, from a digital video signal subjected to lossy encoding on a predetermined image block basis, block noise in a horizontal direction caused by decoding the video signal, said horizontal block boundary detecting apparatus comprising:

a horizontal high-pass filter for receiving the video signal and extracting a horizontal high frequency component of the video signal;

absolute value taking means for taking an absolute value of a high frequency component signal outputted from said horizontal high-pass filter;

vertical accumulating/adding means for accumulating/adding an absolute value signal outputted from said absolute value taking means in a vertical direction;

a high-pass filter for extracting a high frequency component from an accumulated/added high frequency component signal outputted from said vertical accumulating/adding means;

N-point accumulating/adding means for accumulating/adding a signal outputted from said high-pass filter on a predetermined N-point basis, where N is a positive integer;

a temporal filter for detecting a block noise level of the video signal by extending the signal outputted from said high-pass filter in a temporal direction;

maximum value detecting means for determining a maximum value and a position of the maximum value among N-piece accumulated/added values determined by said N-point accumulating/adding means through accumulation/addition; and

masking means for masking the block noise level detected by said temporal filter at the position of the maximum value outputted from said maximum value detecting means, and determining a horizontal block boundary corresponding to the position.

51. A dot clock controlling apparatus for controlling a dot clock to be regenerated in a video processing system in which a digital video signal subjected to lossy encoding on a predetermined image block basis is processed, said dot clock controlling apparatus comprising:

clock generating means for generating the dot clock used in the video processing system in accordance with a horizontal synchronizing pulse,

horizontal block boundary detecting means for receiving the video signal and detecting a longitudinal block boundary, where block noise is generated, on a screen with respect to the video signal; and

controlling means for changing a delay of said clock generating means such that the longitudinal block boundary detected by said horizontal block boundary detecting means periodically has a single maximum point,

wherein said horizontal block boundary detecting means comprises;

a horizontal high-pass filter for receiving the video signal and extracting a horizontal high frequency component of the video signal;

absolute value taking means for taking an absolute value of a high frequency component signal outputted from said horizontal high-pass filter;

vertical accumulating/adding means for accumulating/adding an absolute value signal outputted from said absolute value taking means in a vertical direction;

a high-pass filter for extracting a high frequency component from an accumulated/added high frequency component signal outputted from said vertical accumulating/adding means; and

N-point accumulating/adding means for accumulating/adding a signal outputted from said high-pass filter on a predetermined N-point basis, where N is a positive integer.

52. A program recorded on a recording medium, to be run in a computer device for detecting block noise from a digital video signal subjected to lossy encoding on a predetermined image block basis caused by decoding the video signal, said program comprising:

extracting only a high frequency component from the video signal as an extracted high frequency component signal;

taking an absolute value of the extracted high frequency component signal as an absolute-value-taken high frequency component signal;

accumulating/adding the absolute-value-taken high frequency component signal for a predetermined period;

detecting a periodicity of the block noise in accordance with a result of said accumulating/adding operation; and

determining a block boundary, where the block noise is generated, in accordance with a signal having the periodicity detected by said detecting operation.

53. The program according to claim 52, further comprising eliminating the block noise with respect to the block boundary.

54. The program according to claim 53, wherein said determining of the block boundary comprises distinguishing positional information on the block boundary and positional information on a remainder of an image with binary, values from each other.

55. The program according to claim 53, further comprising:

determining a signal difference among a plurality of predetermined frames of the video signal;

determining a noise region where the block noise to be eliminated is observed with reference to whether or not the signal difference is greater than a predetermined threshold value; and

masking the block boundary in the noise region, and determining a portion of the block boundary corresponding to the noise region.

56. The program according to claim 53, wherein each of said operations is executed in at least one of a horizontal direction and a vertical direction of the video signal.

57. The program according to claim 52, wherein said determining of the block boundary comprises distinguishing positional information on the block boundary and positional information on a remainder of an image, with binary values, from each other.

58. The program according to claim 57, further comprising:

determining a signal difference among a plurality of predetermined frames of the video signal;

determining a noise region where the block noise to be eliminated is observed with reference to whether or not the signal difference is greater than a predetermined threshold value; and

masking the block boundary in the noise region, and determining a portion of the block boundary corresponding to the noise region.

59. The program according to claim 57, wherein each of said operations is executed in at least one of a horizontal direction and a vertical direction of the video signal.

60. The program according to claim 52, further comprising:

determining a signal difference among a plurality of predetermined frames of the video signal;

determining a noise region where the block noise to be eliminated is observed with reference to whether or not the signal difference is greater than a predetermined threshold value; and

masking the block boundary in the noise region, and determining a portion of the block boundary corresponding to the noise region.

61. The program according to claim 60, wherein said determining of the signal difference comprises determining a signal difference between a current frame and a previous frame.

62. The program according to claim 61, wherein said determining of the noise region comprises distinguishing a part of the signal difference exceeding the threshold value and a part of the signal difference not exceeding the threshold value, with binary values, from each other.

63. The program according to claim 61, further comprising eliminating a noise no part in a predetermined small region of the noise region, wherein

said determining a block boundary corresponding to the noise block comprises masking the block boundary in the noise region excluding the noise part.

64. The program according to claim 61, wherein each of said operations is executed in at least one of a horizontal direction and a vertical direction of the video signal.

65. The program according to claim 60, wherein said determining of the noise region comprises distinguishing a part of the signal difference exceeding the threshold value and a part of the signal difference not exceeding the threshold value with binary values, from each other.

66. The program according to claim 65, further comprising eliminating a noise part in a predetermined small region of the noise region, wherein

said determining of the block boundary corresponding to the noise block comprises masking the block boundary in the noise region excluding the noise part.

67. The program according to claim 65, wherein each of said operations is executed in at least one of a horizontal direction and a vertical direction of the video signal.

68. The program according to claim 60, further comprising eliminating a noise part in a predetermined small region of the noise region, wherein

said determining of the block boundary corresponding to the noise block comprises masking the block boundary in the noise region excluding the noise part.

69. The program according to claim 68, wherein each of said operations is executed in at least one of a horizontal direction and a vertical direction of the video signal.

70. The program according to claim 60, wherein each of said operations is executed in at least one of a horizontal direction and a vertical direction of the video signal.

71. The program according to claim 52, wherein each of said operations is executed in at least one of a horizontal direction and a vertical direction of the video signal.

72. The program according to claim 71, wherein, when each of said operations is executed in the vertical direction of the video signal,

said detecting of the periodicity comprises successively changing frames used for detection corresponding to a format of the video signal to be inputted.

73. A program recorded on a recording medium to be run in a computer device for detecting block noise from a digital video signal subjected to lossy encoding on a predetermined image block basis caused by decoding the video signal, said program comprising:

detecting, with respect to the video signal, a vertical block boundary, where the block noise is generated, in a lateral direction and a vertical block noise level on a screen;

detecting, with respect to the video signal, a horizontal block boundary, where the block noise is generated, in a longitudinal direction and a horizontal block noise level on the screen;

specifying a block boundary in both the longitudinal direction and the lateral direction from the vertical block boundary and the horizontal block boundary obtained in said detecting as to the lateral direction and said detecting as to the longitudinal direction, respectively; and

smoothing the video signal in a predetermined manner corresponding to the block boundary in both the longitudinal direction and the lateral direction,

wherein said detecting as to the lateral direction comprises;

extracting a vertical high frequency component from the video signal as an extracted high frequency component signal;

taking an absolute value of the extracted high frequency component signal as an absolute value signal;

accumulating/adding the absolute value signal in a horizontal direction as an accumulated/added high frequency component signal;

extracting a high frequency component from the accumulated/added high frequency component signal as a signal;

accumulating/adding the signal outputted in said extracting of the high frequency component on a predetermined N-point basis where N is a positive integer;

detecting the vertical block noise level of the video signal by extending the signal outputted in said extracting of the high frequency component in a temporal direction;

determining a maximum value and a position of the maximum value among N-piece accumulated/added values determined by said accumulation/addition operation; and

masking the detected vertical block noise level at the position of the maximum value, and determining the vertical block boundary corresponding to the position, and

wherein said detecting as to the longitudinal direction comprises;

extracting a horizontal high frequency component of the video signal as an extracted high frequency component signal;

taking an absolute value of the extracted high frequency component signal as an absolute value signal;

accumulating/adding the absolute value signal in a vertical direction as an accumulated/added high frequency component signal;

extracting a high frequency component from the accumulated/added high frequency component signal as a signal;

accumulating/adding the signal outputted in said extracting of the high frequency component on a predetermined N-point basis;

detecting the horizontal block noise level of the video signal by extending the signal outputted in said extracting of the high frequency component in a temporal direction;

determining a maximum value and a position of the maximum value among N-piece accumulated/added values determined by said accumulation/addition operation; and

masking the detected horizontal block noise level at the position of the maximum value, and determining the horizontal block boundary corresponding to the position.

74. The program according to claim 73, wherein said smoothing operation further comprises:

a horizontal operation of extracting only a horizontal high frequency component of the video signal;

a horizontal multiplying operation of multiplying an output in said horizontal operation and an output in said detecting at to the longitudinal direction;

deducting an output in said horizontal multiplying operation from the video signal;

a vertical operation of extracting a vertical high frequency component of the video signal;

a vertical multiplying operation of multiplying an output in said vertical operation and an output in said detecting as to the lateral direction; and

deducting an output in said vertical multiplying operation from the video signal, wherein

the block noise is eliminated according to the horizontal and vertical block noise levels.

75. The program according to claim 74, further comprising controlling a picture enhancement level emphasizing an outline of the video signal according to the horizontal and vertical block noise levels detected in said step of detecting as to the longitudinal direction and said step of detecting as to the lateral direction, respectively.

76. The program according to claim 74, further comprising specifying the video signal to be inputted in accordance with the horizontal and vertical block noise levels detected in said detecting as to the longitudinal direction and said detecting as to the lateral direction, respectively, as a judgement result, wherein

said specifying comprises displaying the judgement result of the video signal on a screen in a predetermined format.

77. The program according to claim 73, further comprising controlling a picture enhancement level emphasizing an outline of the video signal according to the horizontal and vertical block noise levels detected in said detecting as to the longitudinal direction and said detecting as to the lateral direction, respectively.

78. The program according to claim 73, further comprising specifying the video signal to be inputted in accordance with the horizontal and vertical block noise levels detected in said detecting as to the longitudinal direction and said detecting as to the lateral direction, respectively, as a judgement result, wherein

said specifying comprises displaying the judgement result of the video signal on a screen in a predetermined format.

79. A program recorded on a recording medium to be run in a computer device for detecting block noise from a video signal subjected to lossy encoding on a predetermined image block basis caused by decoding the video signal said program for comprising:

converting an analog video signal into a first digital video signal;

decoding a second digital video signal as a digital-encoded video signal and outputting the second digital video signal including decoded block boundary information;

selecting one of the first digital video signal outputted in said converting operation and the second digital video signal outputted in said decoding and outputting operation, as the video signal, as is externally instructed;

detecting a lateral block boundary, where the block noise is generated, on a screen and a lateral block noise level with respect to the video signal outputted in said selecting operation;

detecting a longitudinal block boundary, where the block noise is generated, on the screen and a longitudinal block noise level with respect to the video signal outputted in said selecting operation;

specifying a block boundary in both the longitudinal direction and the lateral direction from the lateral block boundary and the longitudinal block boundary obtained in said detecting as to the lateral direction and said detecting as to longitudinal direction selected, respectively; and

smoothing the video signal in a predetermined manner according to the block boundary in both the longitudinal direction and the lateral direction, wherein

said detecting as to the lateral direction and said detecting as to the longitudinal direction each comprises outputting the block boundary based on the lateral block boundary and the longitudinal block boundary, respectively, for the first digital video signal outputted in said converting operation, and outputting the block boundary based on the decoded block boundary information for the second digital video signal outputted in said decoding and outputting operation.

80. The program according to claim 79, wherein said detecting as to the lateral direction comprises:

extracting a vertical high frequency component of the video signal as an extracted high frequency component signal;

taking an absolute value of the extracted high frequency component signal as an absolute value signal;

accumulating/adding the absolute value signal in a horizontal direction as an accumulated/added high frequency component signal;

extracting a high frequency component from the accumulated/added high frequency component signal as a signal;

accumulating/adding the signal outputted in said extracting of the high frequency component on a predetermined N-point basis, where N is a positive integer;

detecting the lateral block noise level of the video signal by extending the signal outputted in said extracting of the high frequency component in a temporal direction;

determining a maximum value and a position of the maximum value among N-piece accumulated/added values determined by said a accumulating/adding operation; and

synchronizing with said selecting operation, and selectively outputting one of the block boundary information and the position of the maximum value as a selected block boundary; and

masking the lateral block noise level at the selected block boundary outputted in said selectively outputting operation, and determining a vertical block boundary corresponding to the position of the maximum value as the lateral block boundary, and

said detecting as to the longitudinal direction comprises;

extracting a horizontal high frequency component of the selected video signal as an extracted high frequency component signal;

taking an absolute value of the extracted high frequency component signal as an absolute value signal;

accumulating/adding the absolute value signal in a vertical direction as an accumulated/added high frequency component signal;

extracting a high frequency component from the accumulated/added high frequency component signal as a signal;

accumulating/adding the signal outputted in said extracting of the high frequency component on a predetermined N-point basis;

detecting the longitudinal block noise level of the video signal by extending the signal outputted in said extracting of the high frequency component in a temporal direction;

determining a maximum value and a position of the maximum value among N-piece accumulated/added values determined by said accumulating/adding operation; and

synchronizing with said selecting operation, and selectively outputting one of the block boundary information and the position of the maximum value as a selected block boundary; and

masking the longitudinal block noise level at the selected block boundary outputted in said selectively outputting operation, and determining a horizontal block boundary corresponding to the position of the maximum value at the longitudinal block boundary.

81. The program according to claim 80, wherein said smoothing comprises:

a horizontal operation of extracting only a horizontal high frequency component of the video signal;

a horizontal multiplying operation of multiplying an output in said horizontal operation and an output in said detecting as to the longitudinal direction;

deducting an output in said horizontal multiplying operation from the video signal;

a vertical operation of extracting only a vertical high frequency component of the video signal;

a vertical multiplying operation of multiplying an output in said vertical operation and an output in said detecting as to the lateral direction; and

deducting an output in said vertical multiplying operation from the video signal, wherein

the block noise is eliminated according to the lateral and longitudinal block noise levels.

82. The program according to claim 80, further comprising controlling a picture enhancement level emphasizing an outline of the video signal according to the longitudinal and lateral block noise levels detected in said detecting as to the longitudinal direction and said detecting as to the lateral direction, respectively.

83. The program according to claim 80, further comprising specifying the video signal to be inputted in accordance with the longitudinal and lateral block noise levels detected in said detecting as to the longitudinal direction and said detecting as to the lateral direction, respectively, as a judgement result, wherein

said specifying comprises displaying the judgement result of the video signal on a screen in a predetermined format.

84. The program according to claim 79, further comprising controlling a picture enhancement level emphasizing an outline of the video signal according to the longitudinal and lateral block noise levels detected in said detecting as to the longitudinal direction and said detecting as to the lateral direction, respectively.

85. The program according to claim 79, further comprising specifying the video signal to be inputted in accordance with the longitudinal and lateral block noise levels detected in said detecting as to the longitudinal direction and said detecting as to the lateral direction, respectively, as a judgement result, wherein

said specifying comprises displaying the judgement result of the video signal on a screen in a predetermined format.

86. A program recorded on a recording medium to be run in a computer device for detecting block noise from a digital video signal subjected to lossy encoding on a predetermined image block basis caused by decoding the video signal, said program comprising:

detecting, with respect to the video signal, a vertical block boundary, where the block noise is generated, in a lateral direction and a vertical block noise level on a screen;

detecting, with respect to the video signal, a horizontal block boundary, where the block noise is generated, in a longitudinal direction and a horizontal block noise level on the screen;

specifying a block boundary in both the longitudinal direction and the lateral direction from the vertical block boundary and the horizontal block boundary obtained in said detecting as to the lateral direction and said detecting as to the longitudinal direction, respectively;

smoothing the video signal in a predetermined manner corresponding to the block boundary in both the longitudinal direction and the lateral direction; and

specifying the video signal to be inputted in accordance with the longitudinal and lateral block noise levels detected in said detecting as to longitudinal direction and said detecting as to the lateral directions, respectively, as a judgement result, wherein

said specifying comprises displaying the judgement result on a screen in a predetermined format.

87. A program recorded on a recording medium to be run in a computer device for detecting block noise in one of a vertical direction and a horizontal direction from a digital video signal subjected to lossy encoding on a predetermined image block basis caused by decoding the video signal, said program comprising:

extracting one of a vertical high frequency component and a horizontal high frequency component of the video signal as an extracted high frequency component signal;

taking an absolute value of the extracted high frequency component signal as an absolute value signal;

accumulating/adding the absolute value signal in the horizontal direction or the vertical direction as an accumulated/added high frequency component signal;

extracting a high frequency component from the accumulated/added high frequency component signal as a signal;

accumulating/adding the signal outputted in said extracting of the high frequency component on a predetermined N-point basis, where N is a positive integer;

detecting a block noise level of the video signal by extending the signal outputted in said extracting of the high frequency component in a temporal direction;

determining a maximum value and a position of the maximum value among N-piece accumulated/added values determined by said accumulating/adding operation; and

masking the detected block noise level at the position of the maximum value, and determining a vertical block boundary or a horizontal block boundary corresponding to the position of the maximum value.

88. A program recorded on a recording medium to be run in a computer device for controlling a dot clock to be regenerated in a video processing system in which a digital video signal subjected to lossy encoding on a predetermined image block basis is processed, said program comprising:

receiving the video signal and detecting a block boundary with respect to the video signal, where block noise is generated, in a longitudinal direction on a screen; and

changing a clock delay such that the block boundary detected in said detecting operation periodically has a single maximum point with respect to a clock generating device in which the dot clock used for the video processing system is generated based on a horizontal synchronizing pulse,

wherein said detecting operation step comprises;

extracting a horizontal high frequency component of the video signal as an extracted high frequency component signal;

taking an absolute value of the extracted high frequency component signal as an absolute value signal;

accumulating/adding the absolute value signal in a vertical direction as an accumulated/added high frequency component signal;

extracting a high frequency component from the accumulated/added high frequency component signal as a signal; and

accumulating/adding the signal outputted in said extracting of the high frequency component on a predetermined N-point basis, where N is a positive integer.

89. A block noise eliminating apparatus for detecting and eliminating, from a digital video signal subjected to lossy encoding on a predetermined image block basis, block noise caused by decoding the video signal, said block noise eliminating apparatus comprising:

vertical block boundary detecting means for receiving the video signal and detecting, with respect to the video signal, a vertical block boundary, where the block noise is generated, in a lateral direction and a vertical block noise level on a screen;

horizontal block boundary detecting means for receiving the video signal and detecting, with respect to the video signal, a horizontal block boundary, where the block noise is generated, in a longitudinal direction and a horizontal block noise level on the screen;

block area detecting means for specifying a block boundary in both the longitudinal direction and the lateral direction from the vertical block boundary and the horizontal block boundary detected in said vertical block boundary detecting means and said horizontal block boundary detecting means, respectively;

block boundary smoothing means for smoothing the video signal to be inputted in a predetermined manner corresponding to the block boundary in both the longitudinal direction and the lateral direction specified by said block area detecting means;

picture enhancing means for controlling a picture enhancement level emphasizing an outline part of the video signal according to the horizontal block noise level detected by said horizontal block boundary detecting means and the vertical block noise detected by said vertical block boundary detecting means and

controlling means for specifying the video signal to be inputted in accordance with the horizontal block noise level detected by said horizontal block boundary detecting means and the vertical block noise level detected by said vertical block boundary detecting means, wherein

said controlling means is operable to display a judgement result of the specification of the video signal on a screen in a predetermined format.

90. A program recorded on a recording medium to be run in a computer device for detecting block noise from a digital video signal subjected to lossy encoding on a predetermined image block basis caused by decoding the video signal, said program comprising:

detecting with respect to the video signal, a vertical block boundary, where the block noise is generated, in a lateral direction and a vertical block noise level on a screen;

detecting, with respect to the video signal, a horizontal block boundary, where the block noise is generated, in a longitudinal direction and a horizontal block noise level on the screen;

specifying a block boundary in both the longitudinal direction and the lateral direction from the vertical block boundary and the horizontal block boundary obtained in said detecting as to the lateral direction and said detecting as to the longitudinal direction, respectively;

smoothing the video signal in a predetermined manner corresponding to the block boundary in both the longitudinal direction and the lateral direction;

controlling a picture enhancement level emphasizing an outline of the video signal according to the longitudinal and lateral block noise levels detected in said detecting as to the longitudinal direction and said detecting as to the lateral direction, respectively; and

specifying the video signal to be inputted in accordance with the longitudinal and lateral block noise levels detected in said detecting as to the longitudinal direction and said detecting as to the lateral direction, respectively, as a judgement result, wherein

said specifying comprises displaying the judgement result of the video signal on a screen in a predetermined format.