Error reduction in transformed digital data

• US 6,393,155 B1
• Filed: 11/04/1998
• Issued: 05/21/2002
• Est. Priority Date: 11/04/1998
• Status: Expired due to Term

• Current Assignee: Uniloc 2017 LLC (SoftBank Group Corp.)
• Original Assignee: International Business Machines Corporation
• Inventors: Mitchell, Joan LaVerne, Bright, Martin James
• Primary Examiner(s): Au, Amelia M.
• Assistant Examiner(s): Wu, Jingge
• Application Number:
  US09/186,249
• Time in Patent Office: 1,294 Days
• Field of Search: 382/232, 382/233, 382/238, 382/251-255, 382/248-250, 375/240.2, 375/240.21, 375/240.02, 375/240.17, 375/240.18, 375/240.19, 348/403, 348/405, 348/699
• US Class Current: 382/248
• CPC Class Codes: G06T 9/007 Transform coding, e.g. discrete cosine transform

Abstract

This invention solves problems due to employing error degraded data in digital processing. It particularly solves multi-generation problems wherein transform data degrade during each inverse transform and forward transform cycle even without any processing due to the rounding and clipping errors. It provides methods, systems and devices for reduced-error processing of transform-coded data. After inverse transformation of transform data, high-precision numbers are converted to integers and clipped to an allowed range forming converted data. High-precision differences are obtained by subtracting the high-precision output of the inverse transform from the converted data. The converted data can be manipulated and sent to output devices which expect integer data. Processed high-precision numbers are formed by adding the high-precision differences to the processed converted data. Thus, the rounding and clipping errors are greatly reduced in the processed high-precision numbers. In another embodiment of the present invention processed high-precision numbers are generated by selecting the high-precision numbers instead of the manipulated converted data whenever the manipulated converted data still equals the converted data. Although advantageous to many applications employing digital transformed data, the invention is particularly advantageous for use in digital studios during editing of MPEG-coded, JPEG-coded and wavelet-coded video and audio data.

Claims

1. A method for digitally processing transform data representing a phenomenon, the method comprising:

performing an inverse transform of said transform data to the real domain forming initial high-precision numbers;

converting said initial high-precision numbers to integers and clipping the integers to an allowed range forming initial converted data;

subtracting said converted data from said initial high-precision numbers forming high-precision differences;

manipulating said initial converted data to produce an effect and forming processed converted data; and

adding said high-precision differences to said processed converted data forming processed high-precision numbers.

2. A method as recited in claim 1, wherein said step of adding includes adding intelligently.

3. A method as recited in claim 1, wherein said adding step comprises adding said high-precision differences having magnitudes greater than 1 to said processed converted data only if said processed converted data are at an extreme of the allowed range.

4. A method as recited in claim 1, wherein the phenomenon is an image.

5. A method as recited in claim 4, wherein said effect is the chroma-key merging of two data sets.

6. A method as recited in claim 4, wherein said effect is the color correction of image data.

7. A method as recited in claim 4, wherein said effect is a 90 degree rotation of the image.

8. A method as recited in claim 1, wherein said initial high-precision numbers are fixed precision numbers including a fractional part.

9. A method as recited in claim 1, wherein the step of performing employs an inverse discrete cosine transform.

10. A method as recited in claim 1, further comprising performing a forward transform of said processed high-precision numbers forming processed transform data.

11. A method as recited in claim 10, wherein the inverse to said forward transform is different from said inverse transform.

12. A method as recited in claim 11, wherein said forward transform is a forward discrete cosine transform and said inverse transform is an inverse discrete wavelet transform.

13. A method as recited in claim 1, further comprising performing an inverse quantization of transform-coded data forming the transform data.

14. A method as recited in claim 10, further comprising:

performing an inverse quantization of transform-coded data forming the transform data; and

performing a quantization of said processed transform data forming processed quantized data.

15. A method as recited in claim 14, further comprising:

entropy decoding coded data forming the transform-coded data; and

entropy encoding the processed quantized data.

16. A method as recited in claim 15, wherein said coded data are coded audio data.

17. A method as recited in claim 15, wherein said coded data are coded image data.

18. A method as recited in claim 15, wherein said coded data are coded video data.

19. A method as recited in claim 17, wherein said coded image data are in a JPEG still image international standard format.

20. A method as recited in claim 18, wherein said coded video data are in a MPEG motion video international standard format.

46. A method as recited in claim 1, further comprising providing said converted data for use by an output device.

47. A method as recited in claim 46, wherein the output device is a display monitor.

48. A method as recited in claim 46, wherein the output device is a raster display monitor.

49. A method as recited in claim 1, wherein the transform data includes information of a spectral analysis.

21. A method for digitally processing transform data representing a phenomenon, the method comprising:

performing an inverse transform of said transform data to the real domain forming initial high-precision numbers;

converting said initial high-precision numbers to integers and clipping the integers to an allowed range forming initial converted data;

subtracting said initial high-precision numbers from said initial converted data forming high-precision differences;

manipulating said initial converted data to produce a first effect forming processed converted data;

manipulating said high-precision differences to produce a second effect forming processed high-precision differences; and

adding said processed high-precision differences to said processed converted data forming processed high-precision numbers.

22. A method as recited in claim 21, wherein said adding step comprises adding said processed high-precision differences having magnitudes greater than 1 to said processed converted data only if said processed converted data are at an extreme of the allowed range.

23. A method as recited in claim 21, wherein said first effect is the chroma-key merging of two data sets.

24. A method as recited in claim 23, wherein said second effect is the merging of two high-precision differences according to the chroma-keying merging of two data sets.

25. A method as recited in claim 21, wherein said first effect is the color correction of image data.

26. A method as recited in claim 21, wherein said first effect is a 90 degree rotation of the image and said second effect is a 90 degree rotation of said high-precision differences.

27. A method as recited in claim 21, wherein said high-precision numbers are floating point numbers.

28. A method as recited in claim 21, wherein the step of performing employs an inverse discrete wavelet transform.

29. A method as recited in claim 21, further comprising performing a forward transform of said processed high-precision numbers forming processed transform data.

30. A method as recited in claim 29, wherein the inverse to said forward transform is different from said inverse transform.

31. A method as recited in claim 30, wherein said forward transform is a forward discrete cosine transform and said inverse transform is an inverse discrete wavelet transform.

32. A method as recited in claim 21, further comprising performing an inverse quantization of transform-coded data forming the transform data.

33. A method as recited in claim 29, further comprising:

performing an inverse quantization of transform-coded data forming the transform data; and

performing a quantization of said processed transform data forming processed quantized data.

34. A method as recited in claim 33, further comprising:

entropy decoding coded data forming the transform-coded data; and

entropy encoding the processed quantized data.

35. A method as recited in claim 34, wherein said coded data are coded video data.

36. A method as recited in claim 34, wherein said coded data are in a JPEG still image international standard format.

37. A method as recited in claim 35, wherein said coded video data are in a MPEG motion video international standard format.

38. A system for digitally processing transform data representing a phenomenon, the system comprising:

an inverse transformer to perform an inverse transform of the transform data to the real domain using high-precision numbers;

converter to convert said high-precision numbers to integers, and a clipper to clip the integers to an allowed range;

a subtractor to subtract said converted data from said high-precision numbers forming high-precision differences;

a manipulator to manipulate the converted data to produce an effect forming processed converted data; and

an adder to add said high-precision differences to said processed converted data forming processed high-precision numbers.

39. A system as recited in claim 38, further comprising a forward transformer for performing a forward transform of said processed high-precision numbers forming processed transform data.

40. A system as recited in claim 39, further comprising an inverse quantizer for performing an inverse quantization of transform-coded data forming the transform data.

41. A system as recited in claim 40, further comprising a quantizer for performing a quantization of said processed transform data forming processed quantized data.

42. A system as recited in claim 41, further comprising:

a lossless entropy decoder to form the transform-coded data; and

a lossless entropy encoder to encode the quantized data.

43. A system as recited in claim 42, wherein the quantized data forms an other level of transform-coded data and further comprising:

another inverse quantizer, another inverse transformer, another converter and clipper, another manipulator, another selector, another forward transformer, and another quantizer to perform together a similar function on the other level of transform-coded data as performed on the first level transform-coded data.

44. A system as recited in claim 43, wherein the effect produced by the first manipulator is a different type of effect from that produced by said another manipulator.

45. A system as recited in claim 43, wherein the functions of the first inverse quantizer, first inverse transformer, first converter and clipper, first selector, first forward transformer, and first quantizer, and the respective functions of said another inverse quantizer, another inverse transformer, another converter and clipper, another selector, another forward transformer, and another quantizer are each performed by a same module.

50. An article of manufacture comprising a computer usable medium having computer readable program code means embodied therein for digitally processing transform data representing a phenomenon, the computer readable program code means in said article of manufacture comprising computer readable program code means for causing a computer to effect:

performing an inverse transform of said transform data to the real domain forming initial high-precision numbers;

converting said initial high-precision numbers to integers and clipping the integers to an allowed range forming initial converted data;

subtracting said initial high-precision numbers from said initial converted data forming high-precision differences;

manipulating said initial converted data to produce an effect and forming processed converted data; and

adding said high-precision differences to said processed converted data forming processed high-precision numbers.

51. An article of manufacture as recited in claim 50, wherein the phenomenon is an image.

52. A computer program product as recited in claim 50, the computer readable program code means in said computer program product further comprising computer readable program code means for causing a computer to effect performing a forward transform of said processed high-precision numbers.

53. A computer program product as recited in claim 52, wherein the inverse to said forward transform is different from said inverse transform.

54. A computer program product as recited in claim 52, wherein said forward transform is a forward discrete cosine transform and said inverse transform is an inverse discrete wavelet transform.

55. A program storage device readable by machine, tangibly embodying a program of instructions executable by the machine to perform method steps for digitally processing transform-coded data representing a phenomenon, said method steps comprising:

performing an inverse quantization of said transform-coded data forming transform data;

performing an inverse transform of said transform data to the real domain forming initial high-precision numbers;

converting said initial high-precision numbers to integers and clipping the integers to an allowed range forming initial converted data;

subtracting said initial high-precision numbers from said initial converted data forming high-precision differences;

manipulating said initial converted data to produce an effect and forming processed converted data; and

adding said high-precision differences to said processed converted data forming processed high-precision numbers.

56. A program storage device as recited in claim 55, said method steps comprising:

performing a forward transform of said processed high-precision numbers forming forward transform data; and

performing a quantization of said forward transformed data forming quantized data.

57. A program storage device readable by machine as recited in claim 56, said method steps further comprising:

decoding coded data forming transform-coded data employing entropy decode; and

encoding the quantized data employing entropy encode forming encoded data.

58. A program storage device readable by machine as recited in claim 57, said method steps further comprising alternating said subtracting, manipulating, and adding steps with said steps of performing a forward transform, performing a quantization, entropy encoding, entropy decoding, performing an inverse quantization, and performing an inverse transform a desired number of times.

59. A program storage device readable by machine as recited in claim 58, wherein said coded data are compressed data, and the steps of performing a forward transform, performing a quantization, entropy encoding, entropy decoding, performing an inverse quantization, and performing an inverse transform implement a compression/decompression cycle.

60. A program storage device readable by machine as recited in claim 57, wherein the phenomenon is image data encoded in the JPEG standard format.