Method and apparatus of color system adaptive intensity compensation and video encoding/decoding method and apparatus thereof

• US 20070014479A1
• Filed: 03/21/2006
• Published: 01/18/2007
• Est. Priority Date: 07/15/2005
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Birinov, Dmitri, Cho, Daesung, Kim, Wooshik, Kim, Hyun
• Granted Patent: US 7,657,088 B2
• Time in Patent Office: Days
• US Class Current: 382/238
• CPC Class Codes: H04N 19/117 Filters, e.g. for pre-processing or post-processing sub-band filter banks H04N19/635
• CPC Class Codes: H04N 19/186 the unit being a colour or a chrominance component
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/85 using pre-processing or post-processing specially adapted for video compression

Abstract

A method and apparatus for encoding and/or decoding image data. The encoding method includes: if the color space of an image is a single color space, correcting pixel values by applying identical correction pixel values to all color components of a previous image, and if the color space of the image is not a single color space, correcting pixel values by applying different correction pixel values to the color components of the previous image; performing temporal prediction encoding of a current image by using the corrected pixel values of the previous image; quantizing the prediction encoded data; and generating a bitstream by entropy encoding the quantized data. According to the method and apparatus, when the pixel values of a previous image are desired to be corrected in order to perform temporal prediction encoding, different pixel value correction methods are applied according to whether or not the characteristics of color components included in the color space of the image desired to be encoded. By doing so, when image data is encoded, the encoding can be performed adaptively to a variety of color spaces and higher compression efficiency can be maintained.

Claims

1. An image pixel value correction method of correcting a pixel value of a previous image in order to perform temporal prediction encoding of a current image, the method comprising:

correcting a pixel value of a first color component among pixel values of the previous image using a first proportional constant and a first offset value;

determining whether a color space of the image is a single color space; and

correcting a pixel value corresponding to a color component other than the first color component using the first proportional constant and the first offset value, when the color space of the image is a single color space, and correcting a pixel value corresponding to a color component other than the first color component using a second proportional constant and a second offset value, when the color space of the image is not a single color space,

wherein the single color space is a color space having color components including a chrominance component and a luminance component.

2. The method of claim 1, wherein the second proportional constant is different from the first proportional constant.

3. The method of claim 1, wherein the second offset value is different from the first offset value.

4. The method of claim 1, wherein, when the color space of the image is a YCbCr or a YUV color space, the first color component is the Y component.

5. The method of claim 1, wherein, when the color space of the image is an RGB color space, the first color component is the G component.

6. The method of claim 1, wherein, in the determining of whether the color space of the image is a single color space, information on whether the color space of the image is a single color space is input by a user.

7. The method of claim 1, wherein, in the determining of whether the color space of the image is a single color space, the color space of the image is input by a user and it is determined whether the color space of the image is a single color space is input by a user.

8. The method of claim 1, wherein, in the determining of whether the color space of the image is a single color space, when the color space of the image is an RGB color space, it is determined that the color space of the image is a single color space.

9. The method of claim 1, wherein, in the determining of whether the color space of the image is a single color space, when the color space of the image is a YCbCr or a YUV color space, it is determined that the color space of the image is not a single color space.

10. The method of claim 1, wherein the correcting a pixel value of a first color component comprises:

generating correction pixel values using the first proportional constant and the first offset value; and

correcting the pixel value of the first color component using the correction pixel values generated by using the first proportional constant and the first offset value.

11. The method of claim 10, wherein, in the correcting a pixel value of the color component other than the first color component, when the color space of the image is a single color space, the pixel value of the color component other than the first color component is corrected using the correction pixel values generated using the first proportional constant and the first offset value.

12. The method of claim 10, wherein the correcting a pixel value of the color component other than the first color component, when the color space of the image is not a single color space, comprises:

generating correction pixel values using the second proportional constant and the second offset value; and

correcting the pixel value of the color component other than the first color component using the correction pixel values generated using the second proportional constant and the second offset value.

61. A computer readable recording medium having embodied thereon a computer program for executing the method of claim 1.

13. An image pixel value correction apparatus for correcting the pixel value of a previous image in order to perform temporal prediction encoding of a current image, the apparatus comprising:

a first correction value generation unit generating correction pixel values using a first proportional constant and a first offset value;

a color space determination unit determining whether the color space of the image is a single color space;

a second correction value generation unit generating correction pixel values using a second proportional constant and a second offset value, when the color space of the image is not a single color space; and

a pixel value replacement unit replacing the pixel values of all the color components of the previous image with the correction pixel values generated in the first correction value generation unit, when the color space of the image is a single color space, and replacing the pixel values of the first color component with the correction pixel values generated in the first correction value generation unit and replacing the pixel values of the color components other than the first color component with the correction pixel values generated in the second correction value generation unit, when the color space of the image is not a single color space,

wherein the single color space is a color space having color components including a chroma component and a luma component.

14. The apparatus of claim 13, wherein the second proportional constant is different from the first proportional constant.

15. The apparatus of claim 13, wherein the second offset value is different from the first offset value.

16. The apparatus of claim 13, wherein, when the color space of the image is a YCbCr or a YUV color space, the first color component is the Y component.

17. The apparatus of claim 13, wherein, when the color space of the image is an RGB color space, the first color component is the G component.

18. The apparatus of claim 13, wherein the color space determination unit receives an input of information on whether the color space of the image is a single color space, and determines whether the color space of the image is a single color space using the input information.

19. The apparatus of claim 13, wherein the color space determination unit receives an input of the color space of the image, and determines whether the color space of the image is a single color space.

20. The apparatus of claim 13, wherein, when the color space of the image is an RGB color space, the color space determination unit determines that the color space of the image is a single color space.

21. The apparatus of claim 13, wherein, when the color space of the image is a YCbCr or a YUV color space, the color space determination unit determines that the color space of the image is not a single color space.

22. An image encoding method of encoding an image by using temporal prediction encoding, the method comprising:

correcting pixel values by applying identical correction pixel values to all color components of a previous image, when a color space of an image is a single color space, and correcting pixel values by applying different correction pixel values to the color components of the previous image, when the color space of the image is not a single color space;

performing temporal prediction encoding of a current image using the corrected pixel values of the previous image to yield prediction encoded data;

quantizing the prediction encoded data to yield quantized data; and

generating a bitstream by entropy encoding the quantized data,

wherein the single color space is a color space having color components including a chroma component and a luma component.

23. The method of claim 22, wherein the correcting pixel values of the previous image comprises:

correcting the pixel value of a first color component among pixel values of the previous image using a first proportional constant and a first offset value;

determining whether the color space of the image is a single color space; and

correcting a pixel value corresponding to a color component other than the first color component using the first proportional constant and the first offset value, when the color space of the image is a single color space, and correcting a pixel value corresponding to a color component other than the first color component using a second proportional constant and a second offset value, when the color space of the image is not a single color space.

24. The method of claim 22, wherein, when the color space of the image is a YCbCr or a YUV color space, the first color component is the Y component.

25. The method of claim 22, wherein, when the color space of the image is an RGB color space, the first color component is the G component.

26. The method of claim 23, wherein, in the determining whether the color space of the image is a single color space, when the color space of the image is an RGB color space, it is determined that the color space of the image is a single color space.

27. The method of claim 23, wherein, in the determining whether the color space of the image is a single color space, when the color space of the image is a YCbCr or a YUV color space, it is determined that the color space of the image is not a single color space.

28. The method of claim 23, wherein the correcting a pixel value of the first color component comprises:

generating correction pixel values using the first proportional constant and the first offset value; and

correcting the pixel value of the first color component using the correction pixel values generated using the first proportional constant and the first offset value.

29. The method of claim 23, wherein, in the correcting a pixel value of the color component other than the first color component, when the color space of the image is a single color space, the pixel value of the color component other than the first color component is corrected using the correction pixel values generated using the first proportional constant and the first offset value.

30. The method of claim 23, wherein the correcting a pixel value of the color component other than the first color component, when the color space of the image is not a single color space, comprises:

generating correction pixel values using the second proportional constant and the second offset value; and

correcting the pixel value of the color component other than the first color component using the correction pixel values generated using the second proportional constant and the second offset value.

31. The method of claim 22, wherein, in the generating a bitstream, encoding is performed so that information on whether the image is a single color space is included in the bitstream.

32. The method of claim 22, wherein, in the generating a bitstream, encoding is performed so that the first proportional constant and the first offset value are included in the bitstream.

33. The method of claim 22, wherein, in the generating a bitstream, when the image is not a single color space, encoding is performed so that the second proportional constant and the second offset value are included in the bitstream.

62. A computer readable recording medium having embodied thereon a computer program for executing the method of claim 22.

34. An image encoding apparatus for encoding an image using temporal prediction encoding, the apparatus comprising:

a pixel value correction unit correcting pixel values by applying identical correction pixel values to all color components of a previous image, when the color space of an image is a single color space, and correcting pixel values by applying different correction pixel values to the color components of the previous image, when the color space of the image is not a single color space;

a temporal prediction unit performing temporal prediction encoding of a current image using the corrected pixel values of the previous image to yield prediction encoded data;

a quantization unit quantizing the prediction encoded data to yield quantized data; and

an entropy encoding unit generating a bitstream by entropy encoding the quantized data,

wherein the single color space is a color space having color components including a chroma component and a luma component.

35. The apparatus of claim 34, wherein the pixel value correction unit comprises:

a first correction value generation unit generating correction pixel values using a first proportional constant and a first offset value;

a color space determination unit determining whether the color space of the image is a single color space;

a second correction value generation unit generating correction pixel values by using a second proportional constant and a second offset value, when the color space of the image is not a single color space; and

a pixel value replacement unit replacing the pixel values of all the color components of the previous image, with the correction pixel values generated in the first correction value generation unit, when the color space of the image is a single color space, and replacing the pixel values of the first color component with the correction pixel values generated in the first correction value generation unit and replacing the pixel values of the color components other than the first color component with the correction pixel values generated in the second correction value generation unit, when the color space of the image is not a single color space.

36. The apparatus of claim 35, wherein, when the color space of the image is a YCbCr or a YUV color space, the first color component is the Y component.

37. The apparatus of claim 35, wherein, when the color space of the image is an RGB color space, the first color component is the G component.

38. The apparatus of claim 35, wherein, when the color space of the image is an RGB color space, the color space determination unit determines that the color space of the image is a single color space.

39. The apparatus of claim 35, wherein, when the color space of the image is a YCbCr or a YUV color space, the color space determination unit determines that the color space of the image is not a single color space.

40. The apparatus of claim 35, wherein the entropy encoding unit performs encoding so that information on whether the image is a single color space is included in the bitstream.

41. The apparatus of claim 35, wherein the entropy encoding unit performs encoding so that the first proportional constant and the first offset value are included in the bitstream.

42. The apparatus of claim 34, wherein, when the image is not a single color space, the entropy encoding unit performs encoding so that the second proportional constant and the second offset value are included in the bitstream.

43. An image decoding method of decoding an image from an input bitstream, the method comprising:

entropy decoding the bitstream to yield entropy decoded data;

inverse quantizing the entropy decoded data to yield inverse quantized data;

correcting pixel values by applying identical correction pixel values to all color components of a previous image, when the color space of an image is a single color space, and correcting pixel values by applying different correction pixel values to the color components of the previous image, when the color space of the image is not a single color space; and

performing temporal prediction decoding of data corresponding to a current image among the inverse quantized data using the corrected pixel values of the previous image,

wherein the single color space is a color space having color components including a chroma component and a luma component.

44. The method of claim 43, wherein the correcting pixel values of the previous image comprises:

correcting the pixel value of a first color component among pixel values of the previous image using a first proportional constant and a first offset value;

determining whether the color space of the image is a single color space; and

correcting a pixel value corresponding to a color component other than the first color component using the first proportional constant and the first offset value, when the color space of the image is a single color space, and correcting a pixel value corresponding to a color component other than the first color component using a second proportional constant and a second offset value, when the color space of the image is not a single color space.

45. The method of claim 44, wherein, when the color space of the image is a YCbCr or a YUV color space, the first color component is the Y component.

46. The method of claim 44, wherein, when the color space of the image is an RGB color space, the first color component is the G component.

47. The method of claim 44, wherein, in the determining whether the color space of the image is a single color space, when the color space of the image is an RGB color space, it is determined that the color space of the image is a single color space.

48. The method of claim 44, wherein, in the determining whether the color space of the image is a single color space, when the color space of the image is any one of YCbCr and YUV color spaces, it is determined that the color space of the image is not a single color space.

49. The method of claim 44, wherein, in the determining whether the color space of the image is a single color space, information on whether the color space of the image is a single color space, included in the entropy decoded data, is used.

50. The method of claim 44, wherein information on the first proportional constant and the first offset value is included in the entropy decoded data.

51. The method of claim 44, wherein information on the second proportional constant and the second offset value is included in the entropy decoded data.

63. A computer readable recording medium having embodied thereon a computer program for executing the method of claim 43.

52. An image decoding apparatus of decoding an image from an input bitstream, the method comprising:

an entropy decoding unit entropy decoding the bitstream to yield entropy decoded data;

an inverse quantization unit inverse quantizing the entropy decoded data to yield inverse quantized data;

a pixel value correction unit correcting pixel values by applying identical correction pixel values to all color components of a previous image, when the color space of an image is a single color space, and correcting pixel values by applying different correction pixel values to the color components of the previous image, when the color space of the image is not a single color space; and

a temporal prediction decoding unit, performing temporal prediction decoding of data corresponding to a current image among the inverse quantized data using the corrected pixel values of the previous image,

wherein the single color space is a color space having color components including a chroma component and a luma component.

53. The apparatus of claim 52, wherein the pixel value correction unit comprises:

a first correction value generation unit generating correction pixel values using a first proportional constant and a first offset value;

a color space determination unit determining whether the color space of the image is a single color space;

a second correction value generation unit generating correction pixel values using a second proportional constant and a second offset value, when the color space of the image is not a single color space; and

a pixel value replacement unit replacing the pixel values of all the color components of the previous image, with the correction pixel values generated in the first correction value generation unit, when the color space of the image is a single color space, and replacing the pixel values of the first color component with the correction pixel values generated in the first correction value generation unit and replacing the pixel values of the color components other than the first color component with the correction pixel values generated in the second correction value generation unit, when the color space of the image is not a single color space.

54. The apparatus of claim 53, wherein, when the color space of the image is a YCbCr or a YUV color space, the first color component is the Y component.

55. The apparatus of claim 53, wherein, when the color space of the image is an RGB color space, the first color component is the G component.

56. The apparatus of claim 53, wherein, when the color space of the image is an RGB color space, the color space determination unit determines that the color space of the image is a single color space.

57. The apparatus of claim 53, wherein, when the color space of the image is a YCbCr or a YUV color space, the color space determination unit determines that the color space of the image is not a single color space.

58. The apparatus of claim 53, wherein the color space determination unit determines whether the color space of the image is a single color space using information included in the entropy decoded data.

59. The apparatus of claim 53, wherein information on the first proportional constant and the first offset value is included in the entropy decoded data.

60. The apparatus of claim 53, wherein information on the second proportional constant and the second offset value is included in the entropy decoded data.