Two-stage transform for video signals

• US 5,729,691 A
• Filed: 09/29/1995
• Issued: 03/17/1998
• Est. Priority Date: 09/29/1995
• Status: Expired due to Term

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Agarwal, Robit
• Primary Examiner(s): Trammell, James P.
• Assistant Examiner(s): Peeso, Thomas
• Application Number:
  US08/536,343
• Time in Patent Office: 900 Days
• Field of Search: 364/514 R, 364/715.02, 348/403, 348/394, 348/408, 395/114, 395/200.77, 382/236, 382/238, 382/248, 382/250
• US Class Current: 709/247
• CPC Class Codes: H04N 19/129 Scanning of coding units, e.g. zig-zag scan of transform coefficients or flexible macroblock ordering [FMO]
• CPC Class Codes: H04N 19/63 using sub-band based transform, e.g. wavelets
• CPC Class Codes: H04N 19/70 characterised by syntax aspects related to video coding, e.g. related to compression standards

Abstract

Video signals are encoded by applying a forward transform, where the transform has a first stage that exploits local redundancies in the video signals; and a second stage, following the first stage, that exploits remote redundancies in results of the first stage. The transformed video signals are used to generate an encoded video bitstream. The transformed video signals are decoded by applying an inverse transform that corresponds to the forward transform.

Claims

1. A computer-implemented process for encoding video signals, comprising the steps of:

(a) applying a forward transform to the video signals to generate transformed video signals, wherein the forward transform comprises;

(1) a first stage that exploits local redundancies in the video signals; and

(2) a second stage, following the first stage, that exploits remote redundancies in results of the first stage; and

(b) encoding the transformed video signals to generate an encoded video bitstream.

2. The process of claim 1, wherein:

the first stage applies an invertable frequency decomposition on n input samples to generate n/2 high-frequency values and n/2 low-frequency values; and

the second stage comprises an (n/2×

1) transform that is applied to both the n/2 high-frequency values and the n/2 low-frequency values.

3. The process of claim 2, wherein:

the first stage comprises the first stage of one of a Haar transform and a Daubechies transform; and

the second stage comprises one of a generatized slant transform and a DCT transform.

4. The process of claim 3, wherein the video signals comprise one of pixels and pixel differences.

5. The process of claim 1, wherein the video signals comprise one of pixels and pixel differences.

6. An apparatus for encoding video signals, comprising:

(a) means for applying a forward transform to the video signals to generate transformed video signals, wherein the forward transform comprises;

(1) a first stage that exploits local redundancies in the video signals; and

(2) a second stage, following the first stage, that exploits remote redundancies in results of the first stage; and

(b) means for encoding the transformed video signals to generate an encoded video bitstream.

7. The apparatus of claim 6, wherein:

the first stage applies an invertable frequency decomposition on n input samples to generate n/2 high-frequency values and n/2 low-frequency values; and

the second stage comprises an (n/2×

1) transform that is applied to both the n/2 high-frequency values and the n/2 low-frequency values.

8. The apparatus of claim 7, wherein:

the first stage comprises the first stage of one of a Haar transform and a Daubechies transform; and

the second stage comprises one of a generatized slant transform and a DCT transform.

9. The apparatus of claim 8, wherein the video signals comprise one of pixels and pixel differences.

10. The apparatus of claim 6, wherein the video signals comprise one of pixels and pixel differences.

11. A storage medium having stored thereon a plurality of instructions for encoding video signals, wherein the plurality of instructions, when executed by a processor, cause the processor to perform the steps of:

(a) applying a forward transform to the video signals to generate transformed video signals, wherein the forward transform comprises;

(1) a first stage that exploits local redundancies in the video signals; and

(2) a second stage, following the first stage, that exploits remote redundancies in results of the first stage; and

(b) encoding the transformed video signals to generate an encoded video bitstream.

12. The storage medium of claim 11, wherein:

the first stage applies an invertable frequency decomposition on n input samples to generate n/2 high-frequency values and n/2 low-frequency values; and

the second stage comprises an (n/2×

1) transform that is applied to both the n/2 high-frequency values and the n/2 low-frequency values.

13. The storage medium of claim 12, wherein:

the first stage comprises the first stage of one of a Haar transform and a Daubechies transform; and

the second stage comprises one of a generatized slant transform and a DCT transform.

14. The storage medium of claim 13, wherein the video signals comprise one of pixels and pixel differences.

15. The storage medium of claim 11, wherein the video signals comprise one of pixels and pixel differences.

16. A computer-implemented process for decoding encoded video signals, comprising the steps of:

(a) decoding an encoded bitstream to generate transformed video signals; and

(b) applying an inverse transform to the transformed video signals to generate decoded video signals, wherein the inverse transform corresponds to a forward transform comprising;

(1) a first stage that exploits local redundancies in video signals; and

(2) a second stage, following the first stage, that exploits remote redundancies in results of the first stage.

17. The process of claim 16, wherein:

the first stage applies an invertable frequency decomposition on n input samples to generate n/2 high-frequency values and n/2 low-frequency values; and

the second stage comprises an (n/2×

1) transform that is applied to both the n/2 high-frequency values and the n/2 low-frequency values.

18. The process of claim 17, wherein:

the first stage comprises the first stage of one of a Haar transform and a Daubechies transform; and

the second stage comprises one of a generatized slant transform and a DCT transform.

19. The process of claim 18, wherein the decoded video signals comprise one of pixels and pixel differences.

20. The process of claim 16, wherein the decoded video signals comprise one of pixels and pixel differences.

21. An apparatus for decoding encoded video signals, comprising:

(a) means for decoding an encoded bitstream to generate transformed video signals; and

(b) means for applying an inverse transform to the transformed video signals to generate decoded video signals, wherein the inverse transform corresponds to a forward transform comprising;

(1) a first stage that exploits local redundancies in video signals; and

(2) a second stage, following the first stage, that exploits remote redundancies in results of the first stage.

22. The apparatus of claim 21, wherein:

the first stage applies an invertable frequency decomposition on n input samples to generate n/2 high-frequency values and n/2 low-frequency values; and

the second stage comprises an (n/2×

1) transform that is applied to both the n/2 high-frequency values and the n/2 low-frequency values.

23. The apparatus of claim 22, wherein:

the first stage comprises the first stage of one of a Haar transform and a Daubechies transform; and

the second stage comprises one of a generatized slant transform and a DCT transform.

24. The apparatus of claim 23, wherein the decoded video signals comprise one of pixels and pixel differences.

25. The apparatus of claim 21, wherein the decoded video signals comprise one of pixels and pixel differences.

26. A storage medium having stored thereon a plurality of instructions for decoding encoded video signals, wherein the plurality of instructions, when executed by a processor, cause the processor to perform the steps of:

(a) decoding an encoded bitstream to generate transformed video signals; and

(b) applying an inverse transform to the transformed video signals to generate decoded video signals, wherein the inverse transform corresponds to a forward transform comprising;

(1) a first stage that exploits local redundancies in video signals; and

(2) a second stage, following the first stage, that exploits remote redundancies in results of the first stage.

27. The storage medium of claim 26, wherein:

the first stage applies an invertable frequency decomposition on n input samples to generate n/2 high-frequency values and n/2 low-frequency values; and

the second stage comprises an (n/2×

1) transform that is applied to both the n/2 high-frequency values and the n/2 low-frequency values.

28. The storage medium of claim 27, wherein:

the first stage comprises the first stage of one of a Haar transform and a Daubechies transform; and

the second stage comprises one of a generatized slant transform and a DCT transform.

29. The storage medium of claim 28, wherein the decoded video signals comprise one of pixels and pixel differences.

30. The storage medium of claim 26, wherein the decoded video signals comprise one of pixels and pixel differences.