Resolution conversion upon hierarchical coding and decoding

• US 20040086188A1
• Filed: 10/22/2003
• Published: 05/06/2004
• Est. Priority Date: 10/24/2002
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Owada, Mitsuru
• Granted Patent: US 7,558,441 B2
• Time in Patent Office: Days
• US Class Current: 382/233
• CPC Class Codes: G06T 9/00 Image coding bandwidth or redundancy reduction for static pictures H04N1/41; coding or decoding of static colour picture signals H04N1/64; methods or arrangements for coding, decoding, compressing or decompressing digital video signals H04N19/00
• CPC Class Codes: H04N 19/132 Sampling, masking or truncation of coding units, e.g. adaptive resampling, frame skipping, frame interpolation or high-frequency transform coefficient masking
• CPC Class Codes: H04N 19/134 characterised by the element, parameter or criterion affecting or controlling the adaptive coding
• CPC Class Codes: H04N 19/187 the unit being a scalable video layer
• CPC Class Codes: H04N 19/44 Decoders specially adapted therefor, e.g. video decoders which are asymmetric with respect to the encoder
• CPC Class Codes: H04N 19/59 involving spatial sub-sampling or interpolation, e.g. alteration of picture size or resolution
• CPC Class Codes: H04N 19/635 characterised by filter definition or implementation details

Abstract

In a decoding method of decoding encoded image data which has been hierarchically encoded in advance, a size of an image to be outputted is determined, and then the encoded image data is decoded up to a layer of hierarchy which is at least one layer more than a minimum number of layer/layers of hierarchy necessary to acquire an image of the determined size.

Claims

1. A decoding method of decoding encoded image data which has been hierarchically encoded in advance, comprising:

determining a size of an image to be outputted; and

decoding the encoded image data up to a layer of hierarchy which is at least one layer more than a minimum number of layer/layers of hierarchy necessary to acquire an image of the determined size.

2. The decoding method according to claim 1, wherein said decoding includes:

determining the minimum number of layer/layers of hierarchy necessary to acquire the image of the determined size; and

decoding the encoded image data up to a layer of hierarchy which is at least one layer more than the determined minimum number of layer/layers of hierarchy.

3. The decoding method according to claim 1, wherein said decoding includes:

determining a layer/layers of hierarchy each of which, when the encoded image data is decoded up to each layer, makes a size of a decoded image exceed the determined size; and

decoding the encoded image data up to a layer of hierarchy which is at least one layer more than the lowest of the determined layer/layers.

4. The decoding method according to claim 1, wherein said decoding includes:

decoding a lowest layer of hierarchy of encoded image data among layer/layers which has/have not been decoded, comparing a size of an image obtained by decoding the encoded image data and the determined size, and repeating the decoding of a lowest layer of hierarchy of the encoded image data among the layer/layers which has/have not been decoded when the size of the decoded image is smaller than the determined size; and

decoding a next lowest layer of hierarchy of the encoded image data.

5. The decoding method according to claim 1, wherein said decoding includes:

acquiring a layer of hierarchy which is at least one layer more than a minimum number of layer/layers of hierarchy necessary to obtain a decoded image of the determined size using a look up table on the basis of a size of an image to be obtained by decoding all of the encoded image data and the determined image size; and

decoding the encoded image data up to the acquired layer of hierarchy.

6. The decoding method according to claim 1, further comprising reducing the size of the decoded image to the determined size.

7. The decoding method according to claim 1, further comprising determining whether the minimum number of layer/layers of hierarchy corresponds to all the layers of hierarchy of the encoded image data,

wherein if the determination proves true, all the layers of hierarchy of the encoded image data are decoded.

8. The decoding method according to claim 1, wherein the determined size includes horizontal pixel number information and vertical pixel number information.

9. The decoding method according to claim 1, wherein an encoding method used is a discrete wavelet transform method.

10. The decoding method according to claim 1, wherein an encoding method used conforms to JPEG2000.

12. A storage medium, readable by an information processing apparatus, storing a program including program codes capable of realizing the decoding method according to claim 1, the program being executable by the information processing apparatus.

11. A decoding apparatus for decoding encoded image data which has been hierarchically encoded in advance, comprising:

a determination unit that determines a size of an image to be outputted; and

a decoding unit that decodes the encoded image data up to a layer of hierarchy which is at least one layer more than a minimum number of layer/layers of hierarchy necessary to acquire an image of the determined size.

13. An encoding method of hierarchically encoding an image, comprising:

determining a size of an image to be outputted; and

encoding the image up to a layer of hierarchy which is at least one layer more than a minimum number of layer/layers of hierarchy necessary to acquire an image of the determined size.

14. The encoding method according to claim 13, wherein said encoding includes:

determining the minimum number of layer/layers of hierarchy necessary to acquire an image of the determined size; and

encoding the image up to a layer of hierarchy which is at least one layer more than the determined minimum number of layer/layers of hierarchy.

15. The encoding method according to claim 13, wherein said encoding includes:

determining a layer/layers of hierarchy each of which, when the image is encoded up to each layer, makes a size of an encoded image exceed the determined size; and

encoding the image up to a layer of hierarchy which is at least one layer more than the lowest of the determined layer/layers.

16. The encoding method according to claim 13, wherein said encoding includes:

encoding a lowest layer of hierarchy of an image among layer/layers which has/have not been encoded, comparing a size of an encoded image and the determined size, and repeating encoding of a lowest layer of hierarchy of the image among the layer/layers which has/have not decoded when the size of the encoded image is smaller than the determined size; and

encoding a next lowest layer of hierarchy of the image.

17. The encoding method according to claim 13, wherein said encoding includes:

acquiring a layer of hierarchy which is at least one layer more than a minimum number of layer/layers of hierarchy necessary to obtain an encoded image of the determined size using a look up table on the basis of a size of the image and the determined image size; and

encoding the image up to the acquired layer of hierarchy.

18. The encoding method according to claim 13, further comprising determining whether the minimum number of layer/layers of hierarchy corresponds to all the layers of hierarchy to which the image data can be encoded,

wherein if the determination proves true, the image are encoded up to the possible layer.

19. The encoding method according to claim 13, wherein the determined size includes horizontal pixel number information and vertical pixel number information.

20. The encoding method according to claim 13, wherein an encoding method is a discrete wavelet transform method.

21. The encoding method according to claim 13, wherein an encoding method conforms to JPEG2000.

23. A storage medium, readable by an information processing apparatus, storing a program including program codes capable of realizing the encoding method according to claim 13, the program being executable by the information processing apparatus.

22. An encoding apparatus for hierarchically encoding an image, comprising:

a determination unit that determines a size of an image to be outputted; and

an encoding unit that encodes the image up to a layer of hierarchy which is at least one layer more than a minimum number of layer/layers of hierarchy necessary to acquire an image of the determined size.

24. An encoding method of hierarchically encoding an image, comprising:

restraining a frequency component which causes alias of an image signal of the image at the time of separating the image signal into layers of hierarchy; and

separating the restrained image signal into layers of hierarchy.

25. The encoding method according to claim 24, wherein said restraining includes:

restraining a high frequency component of the input image signal; and

restraining a low frequency component of the input image signal.

26. The encoding method according to claim 25, wherein a low pass filter is used in said restraining of the high frequency component, and an output from said low pass filter is subtracted from the input image signal in said restraining of the low frequency component.

27. The encoding method according to claim 25, wherein a high pass filter is used in said restraining of the low frequency component, and an output from the high pass filter is subtracted from the input image signal in said restraining of the high frequency component.

28. The encoding method according to claim 25, wherein a low pass filter is used in said restraining of the high frequency component, and a high pass filter is used in said restraining of the low frequency component.

29. The encoding method according to claim 25, repeating said restraining and said separating for an image signal obtained by separating the image signal whose high frequency component is restrained.

30. The encoding method according to claim 26, wherein a filter is used in said separating, and a passband of the low pass filter is narrower than a passband of the filter used in said separating.

31. The encoding method according to claim 28, wherein a filter is used in said separating, and a passband of the low pass filter is narrower than a passband of the filter used in said separating.

32. The encoding method according to claim 27, wherein a filter is used in said separating, and a passband of the high pass filter is narrower than a passband of the filter used in said separating.

33. The encoding method according to claim 28, wherein a filter is used in said separating, and a passband of the high pass filter is narrower than a passband of the filter used in said separating.

34. The encoding method according to claim 25, wherein in said restraining of a high frequency component and a low frequency component, at least either one of a horizontal component and a vertical component of the image signal is restrained.

35. The encoding method according to claim 24, wherein an encoding method is a discrete wavelet transform method.

36. The encoding method according to claim 24, wherein an encoding method uses an orthogonal mirror filter at least.

37. The encoding method according to claim 24, wherein an encoding method conforms to JPEG2000.

52. A storage medium, readable by an information processing apparatus, storing a program including program codes capable of realizing the encoding method according to claim 24, the program being executable by the information processing apparatus.

38. An encoding apparatus for hierarchically encoding an image, comprising:

a frequency restraining unit that restrains a frequency component which causes alias of an image signal of the image at the time of separating the image signal into layers of hierarchy; and

a separating unit that separates the image signal restrained by said frequency restraining unit into layers of hierarchy.

39. The encoding apparatus according to claim 38, wherein said frequency restraining unit comprises:

a first restraining unit which restrains a high frequency component of the input image signal; and

a second restraining unit that restrains a low frequency component of the input image signal.

40. The encoding apparatus according to claim 39, wherein said first restraining unit is a low pass filter, and said second restraining unit is a subtractor which subtracts the image signal restrained by said first restraining unit from the input image signal.

41. The encoding apparatus according to claim 39, wherein said second restraining unit is a high pass filter, and said first restraining unit is a subtractor which subtracts the image signal restrained by said second restraining unit from the input image signal.

42. The encoding apparatus according to claim 39, wherein said first restraining unit is a low pass filter, and said second restraining unit is a high pass filter.

43. The encoding apparatus according to claim 39, wherein said frequency restraining unit and said separating unit recursively perform processes on an image signal obtained by separating by said separating unit the image signal restrained by said first restraining unit.

44. The encoding apparatus according to claim 40, wherein said separating unit includes a filter, and a passband of the low pass filter is narrower than the passband of the filter of the separating unit.

45. The encoding apparatus according to claim 42, wherein said separating unit includes a filter, and a passband of the low pass filter is narrower than the passband of the filter of the separating unit.

46. The encoding apparatus according to claim 41, wherein said separating unit includes a filter, and a passband of the high pass filter is narrower than the passband of the filter of the separating unit.

47. The encoding apparatus according to claim 41, wherein said separating unit includes a filter, and a passband of the high pass filter is narrower than the passband of the filter of the separating unit.

48. The encoding method according to claim 39, wherein said first and second restraining unit restrain at least either one of a horizontal component and a vertical component of the image.

49. The encoding apparatus according claim 38, wherein an encoding method is a discrete wavelet transform method.

50. The encoding apparatus according to claim 38, wherein an encoding method uses an orthogonal mirror filter at least.

51. The encoding apparatus according to claim 38, wherein an encoding method conforms to JPEG2000.

53. A decoding method of decoding encoded image data which has been hierarchically encoded in advance, comprising:

determining a layer of hierarchy up to which the encoded image data is to be decoded;

decoding the encoded image data up to the determined layer;

judging whether or not the determined layer corresponds to the highest layer of hierarchy of the encoded image data; and

restraining, when the determined layer does not correspond to the highest layer, a frequency component, which causes alias, of the decoded image data.

56. The decoding method according to claim 53, wherein a low pass filter is used in said restraining.

59. The decoding method according to claim 53, wherein in said restraining, at least a horizontal component or a vertical component is restrained.

62. The decoding method according to claim 53, wherein an encoding method is a discrete wavelet transform method.

65. The decoding method according to claim 53, wherein an encoding method conforms to JPEG2000.

83. A storage medium, readable by an information processing apparatus, storing a program including program codes capable of realizing the decoding method according to claim 53, the program being executable by the information processing apparatus.

54. A decoding method of decoding encoded image data which has been hierarchically encoded in advance, comprising:

decoding all of the encoded image data;

judging whether or not the encoded image data was obtained as a result of encoding all layers of hierarchy; and

restraining, when all the layers of hierarchy have not been encoded, a frequency component, which causes alias, of the decoded image data.

57. The decoding method according to claim 54, wherein a low pass filter is used in said restraining.

60. The decoding method according to claim 54, wherein in said restraining, at least a horizontal component or a vertical component is restrained.

63. The decoding method according to claim 54, wherein an encoding method is a discrete wavelet transform method.

66. The decoding method according to claim 54, wherein an encoding method conforms to JPEG2000.

84. A storage medium, readable by an information processing apparatus, storing a program including program codes capable of realizing the decoding method according to claim 54, the program being executable by the information processing apparatus.

55. A decoding method of decoding encoded image data which has been hierarchically encoded in advance, comprising:

inputting encoded image data from external;

determining a layer of hierarchy up to which the encoded image data is to be decoded;

decoding the encoded image data up to the determined layer;

judging whether or not all layers of hierarchy of the encoded image data have been decoded; and

restraining, when all the layers of hierarchy have not been decoded, a frequency component, which causes alias, of the decoded image data.

58. The decoding method according to claim 55, wherein a low pass filter is used in said restraining.

61. The decoding method according to claim 55, wherein in said restraining, at least a horizontal component or a vertical component is restrained.

64. The decoding method according to claim 55, wherein an encoding method is a discrete wavelet transform method.

67. The decoding method according to claim 55, wherein an encoding method conforms to JPEG2000.

85. A storage medium, readable by an information processing apparatus, storing a program including program codes capable of realizing the decoding method according to claim 55, the program being executable by the information processing apparatus.

68. A decoding apparatus for decoding encoded image data which has been hierarchically encoded in advance, comprising:

a determination unit that determines a layer of hierarchy up to which the encoded image data is to be decoded;

a decoder which decodes the encoded image data up to the determined layer;

a judging unit that judges whether or not the determined layer corresponds to the highest layer of hierarchy of the encoded image data; and

a restraining unit that restrains, when the determined hierarchy does not corresponds to the highest layer, a frequency component, which causes alias, of the decoded image data.

71. The decoding apparatus according to claim 68, wherein said restraining unit uses a low pass filter.

74. The decoding apparatus according to claim 68, wherein said restraining unit restrains at least a horizontal component or a vertical component.

77. The decoding apparatus according to claim 68, wherein an encoding method is a discrete wavelet transform method.

80. The decoding apparatus according to claim 68, wherein an encoding method conforms to JPEG2000.

69. A decoding apparatus for decoding encoded image data which has been hierarchically encoded in advance, comprising:

a decoder that decodes all of the encoded image data;

a judging unit which judges whether or not the encoded image data was obtained as a result of encoding all layers of hierarchy; and

a restraining unit that restrains, when all the layers of hierarchy have not been encoded, a frequency component, which causes alias, of the decoded image data.

72. The decoding apparatus according to claim 69, wherein said restraining unit uses a low pass filter.

75. The decoding apparatus according to claim 69, wherein said restraining unit restrains at least a horizontal component or a vertical component.

78. The decoding apparatus according to claim 69, wherein an encoding method is a discrete wavelet transform method.

81. The decoding apparatus according to claim 69, wherein an encoding method conforms to JPEG2000.

70. A decoding apparatus for decoding encoded image data which has been hierarchically encoded in advance, comprising:

an input unit that inputs encoded image data from external;

a determination unit that determines a layer of hierarchy up to which the encoded image data is to be decoded;

a decoder that decodes the encoded image data up to the determined layer;

a judging unit that judges whether or not all layers of hierarchy of the encoded image data have been decoded; and

a restraining unit that restrains, when all the layers of hierarchy have not been decoded, a frequency component, which causes alias, of the decoded image data.

73. The decoding apparatus according to claim 70, wherein said restraining unit uses a low pass filter.

76. The decoding apparatus according to claim 70, wherein said restraining unit restrains at least a horizontal component or a vertical component.

79. The decoding apparatus according to claim 70, wherein an encoding method is a discrete wavelet transform method.

82. The decoding apparatus according to claim 70, wherein an encoding method conforms to JPEG2000.