Method for reduced bit-depth quantization

• US 20030206585A1
• Filed: 05/02/2002
• Published: 11/06/2003
• Est. Priority Date: 08/09/2001
• Status: Active Grant

• Current Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Kerofsky, Louis Joseph
• Granted Patent: US 7,123,655 B2
• Time in Patent Office: Days
• US Class Current: 375/240.03
• CPC Class Codes: H03M 7/24 Conversion to or from floating-point codes
• CPC Class Codes: H04N 19/126 Details of normalisation or weighting functions, e.g. normalisation matrices or variable uniform quantisers
• CPC Class Codes: H04N 19/136 Incoming video signal characteristics or properties
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/18 the unit being a set of transform coefficients
• CPC Class Codes: H04N 19/184 the unit being bits, e.g. of the compressed video stream
• CPC Class Codes: H04N 19/42 characterised by implementation details or hardware specially adapted for video compression or decompression, e.g. dedicated software implementation H04N19/635 takes precedence

Abstract

A method is provided for the quantization of a coefficient. The method comprises: supplying a coefficient K; supplying a quantization parameter (QP); forming a quantization value (L) from the coefficient K using a mantissa portion (Am)(QP)) and an exponential portion (x^Ae(QP)). Typically, the value of x is 2. In some aspects of the method, forming a quantization value (L) from the coefficient K includes L=K*A(QP)=K*Am(QP)*(2^Ae(QP)). In other aspects, the method further comprises: normalizing the quantization value by 2^N as follows: Ln=L/2^N=K*Am(QP)/2^(N-Ae(QP)). In some aspects, forming a quantization value includes forming a set of recursive quantization factors with a period P, where A(QP+P)=A(QP)/x. Forming recursive quantization factors includes forming recursive mantissa factors, where Am(QP)=Am(QP mod P), and forming recursive quantization factors includes forming recursive exponential factors, where Ae(QP)=Ae(QP mod P)−QP/P.

Claims

1. A method for the quantization of a coefficient, the method comprising:

supplying a coefficient K;

supplying a quantization parameter (QP);

forming a quantization value (L) from the coefficient K using a mantissa portion (Am)(QP)) and an exponential portion (x^Ae(QP)).

2. The method of claim 1 wherein the exponential portion (x^Ae(QP)) includes x being the value 2.

3. The method of claim 2 wherein forming a quantization value (L) from the coefficient K using a mantissa portion (Am)(QP)) and an exponential portion (x^Ae(QP)) includes:

4. The method of claim 3 further comprising:

normalizing the quantization value by 2^N as follows;

$\mathrm{Ln}=\frac{L}{2^N}=K*\mathrm{Am}<br><br>\frac{\left(\mathrm{QP}\right)}{2^{\left(N-\mathrm{Ae}<br><br>\left(\mathrm{QP}\right)\right)}}.$

5. The method of claim 1 wherein forming a quantization value includes forming a set of recursive quantization factors with a period P, where A(QP+P)=A(QP)/x.

6. The method of claim 5 wherein forming a set of recursive quantization factors includes forming recursive mantissa factors, where Am(QP)=Am(QP mod P).

7. The method of claim 5 forming a set of recursive quantization factors includes forming recursive exponential factors, where Ae(QP)=Ae(QP mod P)−

QP/P.

8. The method of claim 4 wherein forming a quantization value includes forming a set of recursive quantization factors with a period P, where A(QP+P)=A(QP)/2.

9. The method of claim 6 wherein forming a set of recursive quantization factors includes forming recursive mantissa factors, where P=6.

10. The method of claim 7 forming a set of recursive quantization factors includes forming recursive exponential factors, where P=6.

11. The method of claim 1 wherein supplying a coefficient K includes supplying a coefficient matrix K[i][j];

wherein forming a quantization value (L) from the coefficient matrix K[i][j] using a mantissa portion (Am)(QP) and an exponential portion (x^Ae(QP)) includes forming a quantization value matrix (L[i][j]) using a mantissa portion matrix (Am(QP)[i][j]) and an exponential portion matrix (x^{Ae(QP)[i][j]).}

12. The method of claim 11 wherein forming a quantization value matrix (L[i][j]) using a mantissa portion matrix (Am(QP)[i][j]) and an exponential portion matrix (x^{Ae(QP)[i][j]) includes, for each particular value of QP, every element in the exponential portion matrix being the same value.}

13. The method of claim 12 wherein every element in the exponential portion matrix is the same value for a period (P) of QP values, where Ae(QP)=Ae(P*(QP/P)).

14. The method of claim 1 further comprising:

forming a dequantization value (X1) from the quantization value, using a mantissa portion (Bm)(QP)) and an exponential portion (x^Be(QP)).

15. The method of claim 14 wherein the exponential portion (x^Be(QP)) includes x being the value 2.

16. The method of claim 15 wherein forming a dequantization value (X1) from the quantization value, using a mantissa portion (Bm)(QP)) and an exponential portion (2^Be(QP)) includes:

17. The method of claim 16 further comprising:

denormalizing the quantization value by 2^N as follows;

$\begin{array}{c}\mathrm{X1d}=<br><br>\mathrm{X1}/2^N\\ =<br><br>\mathrm{X1}*\mathrm{Bm}<br><br>\left(\mathrm{QP}\right)/2^N.\end{array}$

18. The method of claim 14 wherein forming a dequantization value includes forming a set of recursive dequantization factors with a period P, where B(QP+P)=x*B(QP).

19. The method of claim 18 wherein forming a set of recursive dequantization factors includes forming recursive mantissa factors, where Bm(QP)=Bm(QP mod P).

20. The method of claim 19 forming a set of recursive dequantization factors includes forming recursive exponential factors, where Be(QP)=Be(QP mod P)+QP/P.

21. The method of claim 18 wherein forming a set of recursive quantization factors with a period P includes the value of x being equal to 2.

22. The method of claim 19 wherein forming recursive mantissa factors includes the value of P being equal to 6.

23. The method of claim 22 forming a set of recursive dequantization factors includes forming recursive exponential factors, where Be(QP)=Be(QP mod P)+QP/P.

24. The method of claim 14 wherein forming a dequantization value (X1) from the quantization value, using a mantissa portion (Bm)(QP)) and an exponential portion (x^Be(QP)) includes forming a dequantization value matrix (X1[i][j]) using a mantissa portion matrix (Bm(QP)[i][j]) and an exponential portion matrix (x^{Be(QP)[i][j])}.

25. The method of claim 24 wherein forming a dequantization value matrix (X1[i][j]) using a mantissa portion matrix (Bm(QP)[i][j]) and an exponential portion matrix (x^Be(QP)[i][j]) includes, for each particular value of QP, every element in the exponential portion matrix being the same value.

26. The method of claim 23 wherein every element in the exponential portion matrix is the same value for a period (P) of QP values, where Be(QP)=Be(P*(QP/P)).

27. A method for the dequantization of a coefficient, the method comprising:

receiving a quantization value;

forming a dequantization value (X1) from the quantization value, using a mantissa portion (Bm)(QP)) and an exponential portion (x^Be(QP)).

28. The method of claim 27 wherein the exponential portion (x^Be(QP)) includes x being the value 2.

29. The method of claim 28 wherein forming a dequantization value (X1) from the quantization value, using a mantissa portion (Bm)(QP)) and an exponential portion (2^Be(QP)) includes:

30. The method of claim 29 wherein receiving the quantization value includes received a normalized quantization value;

and,

the method further comprising;

denormalizing the quantization value by 2^N as follows;

$\begin{array}{c}\mathrm{X1d}=<br><br>\mathrm{X1}/2^N\\ =<br><br>\mathrm{X1}*\mathrm{Bm}<br><br>\left(\mathrm{QP}\right)/2^N.\end{array}$

31. The method of claim 27 wherein forming a dequantization value includes forming a set of recursive dequantization factors with a period P, where B(QP+P)=x*B(QP).

32. The method of claim 31 wherein forming a set of recursive dequantization factors includes forming recursive mantissa factors, where Bm(QP)=Bm(QP mod P).

33. The method of claim 32 forming a set of recursive dequantization factors includes forming recursive exponential factors, where Be(QP)=Be(QP mod P)+QP/P.

34. The method of claim 31 wherein forming a set of recursive quantization factors with a period P includes the value of x being equal to 2.

35. The method of claim 32 wherein forming recursive mantissa factors includes the value of P being equal to 6.

36. The method of claim 35 forming a set of recursive dequantization factors includes forming recursive exponential factors, where Be(QP)=Be(QP mod P)+QP/P.

37. The method of claim 27 wherein forming a dequantization value (X1) from the quantization value, using a mantissa portion (Bm)(QP)) and an exponential portion (x^Be(QP)) includes forming a dequantization value matrix (X1[i][j]) using a mantissa portion matrix (Bm(QP)[i][j]) and an exponential portion matrix (x^Be(QP)[i][j]).

38. The method of claim 37 wherein forming a dequantization value matrix (X1[i][j]) using a mantissa portion matrix (Bm(QP)[i][j]) and an exponential portion matrix (x^Be(QP)[i][j]) includes, for each particular value of QP, every element in the exponential portion matrix being the same value.

39. The method of claim 36 wherein every element in the exponential portion matrix is the same value for a period (P) of QP values, where Be(QP)=Be(P*(QP/P)).