Color image residue transformation and/or inverse transformation method and apparatus, and color image encoding and/or decoding method and apparatus using the same

• US 8,036,478 B2
• Filed: 11/26/2004
• Issued: 10/11/2011
• Est. Priority Date: 11/26/2003
• Status: Expired due to Fees

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kim, Woo-shik, Kim, Hyun-mun
• Primary Examiner(s): Repko; Jason M
• Assistant Examiner(s): Thomas; Mia M
• Application Number:
  US10/996,448
• Publication Number:
  US 20050111741A1
• Time in Patent Office: 2,510 Days
• Field of Search: 382/165, 382/166, 382/236, 382/244, 382/248, 382/232, 382/251, 345/98, 345/589, 348/441, 348/699, 375/240.16, 375/240.24
• US Class Current: 382/232
• CPC Class Codes: H04N 19/107 between spatial and temporal predictive coding, e.g. picture refresh
• CPC Class Codes: H04N 19/122 Selection of transform size, e.g. 8x8 or 2x4x8 DCT; Selection of sub-band transforms of varying structure or type
• CPC Class Codes: H04N 19/124 Quantisation
• CPC Class Codes: H04N 19/136 Incoming video signal characteristics or properties
• CPC Class Codes: H04N 19/172 the region being a picture, frame or field
• CPC Class Codes: H04N 19/186 the unit being a colour or a chrominance component
• CPC Class Codes: H04N 19/50 using predictive coding H04N19/61 takes precedence
• CPC Class Codes: H04N 19/593 involving spatial prediction techniques

Abstract

A color image residue transform and/or inverse transform method and apparatus, and a color image encoding and/or decoding method and apparatus using the same are provided. The residue transform method includes: obtaining a residue corresponding to the difference of an original image and a predicted image; and transforming the residue by using a relation between residues of color image components. The residue inverse transform method includes: generating a residue for each component by performing residue inverse transform of the residue transformed original image; and restoring the original image by adding a predicted image to the residue of each component. Also, the color image lossless encoding method using the residue transform includes: obtaining a residue corresponding to the difference of an original image and a predicted image; and performing encoding by transforming the residue by using the relation between residues of predetermined components. The decoding method includes: extracting residue transformed image data from the coded data of the original image; generating a residue for each component by performing residue inverse transform of the residue transformed image data; and restoring the original image by adding a predicted image to the residue of each component. According to the methods and apparatuses, by performing transform between residues of each color component, the redundancy of the residue of each color component is removed such that when a color image is encoded, a higher compression efficiency can be achieved.

Claims

1. A color image encoding method using residue transform for encoding an original color image formed with at least two or more components, the method comprising:

obtaining, for each component of the original color image, a residue corresponding to the difference of the original color image and a predicted image generated from a restored image;

selecting whether or not to transform the residue by using a relation between residues of respective components of the original color image; and

transforming the residue and encoding the transformed residue if the transforming of the residue is selected, or if the transforming of the residue is not selected, encoding the obtained residue, wherein the encoding of the obtained residue includes at least quantization.

2. The method of claim 1, wherein the original image has any one of an R-G-B format, a Y-Cb-Cr format, and an X-Y-Z format.

3. The method of claim 2, wherein the obtaining of the residue corresponding to the difference comprises:

obtaining a predicted image for each component of the original image, by estimating motions in units of blocks of a predetermined size between the restored previous frame and the current frame of the color component; and

obtaining a lossy temporal residue by subtracting the predicted image from the original image.

4. The method of claim 2, wherein the obtaining of the residue corresponding to the difference comprises:

in a case of intra mode, obtaining a lossy predicted image for each component of the original image, by estimating a prediction direction from pixels spatially adjacent to the pixel block of a current frame of the color component and obtaining a spatial residue by subtracting the lossy predicted image from the original image; and

in a case of inter mode, obtaining a lossy predicted image for each component of the original image, by estimating motions in units of blocks of a predetermined size between the restored previous frame and the current frame of the color component and obtaining a temporal residue by subtracting the predicted image from the original image.

5. The method of claim 2, wherein the predicted image in the obtaining of the residue corresponding to the difference is generated by using an image which is restored by performing inverse quantization and inverse transform of the signal generated through the transform and quantization in the encoding of the residue transformed data, and then performing prediction compensation.

6. The method of claim 2, wherein in the transforming of the residue by using the relation, assuming that three components of the color image are X₁, X₂, and X₃, and Δ

X₁, Δ

X₂, and Δ

X₃ are residues of X₁, X₂, and X₃, respectively, the transform is performed by subtracting the residue value of one component from the residue values of the remaining two component among the three components as the following equation;

7. The method of claim 2, wherein in the transforming of the residue by using the relation, assuming that three components of the color image are X₁, X₂, and X₃, and Δ

X₁, Δ

X₂, and Δ

X₃ are residues of X₁, X₂, and X₃, respectively, the transform is performed by using the following equation;

8. The method of claim 2, wherein in the transforming of the residue by using the relation, assuming that three components of the color image are X₁, X₂, and X₃, and Δ

X₁, Δ

X₂, and Δ

X₃ are residues of X₁, X₂, and X₃, respectively, the transform is performed by using the following equations;

Δ

²X₁=Δ

X₂−

Δ

X₃

t=Δ

X₃+(Δ

²X₁>

>

1)

Δ

²X₃=Δ

X₁−

t

Δ

²X₂=t+(Δ

²X₃>

>

1)

where Δ

²X₁, Δ

²X₂, and Δ

²X₃ are residue transformed signals.

9. The method of claim 1, further comprising:

entropy coding the quantized data and generating a bitstream.

10. The method of claim 1, wherein the obtaining of the residue corresponding to the difference comprises:

obtaining a lossy predicted image for each component of the original image, by estimating a prediction direction from pixels spatially adjacent to the pixel block of a current frame of the color component; and

obtaining a lossy spatial residue by subtracting the lossy predicted image from the original image.

11. A non-transitory computer readable recording medium encoded with computer readable code comprising a program for implementing the method of claim 1.

12. A color image encoding method using residue transform for encoding an original color image formed with at least two or more components, the method comprising:

obtaining a residue corresponding to the difference of the original color image and a predicted image generated from a restored image, for each component of the original color image;

selecting whether or not to perform residue transform by using a relation between residues of respective components of the original color image;

if residue transform is selected, performing lossy encoding by transforming the residue using the relation between the residues of the respective components of the original color image; and

if residue transform is not selected, lossy encoding the residue of each component of the original color image.

13. The method of claim 12, wherein, in the transforming of the residue by using the relation, assuming that three components of the color image are X1, X2, and X3, and Δ

X1, Δ

X2, and Δ

X3 are residues of X1, X2, and X3, respectively, the transform is performed by subtracting the residue value of one component from the residue values of the remaining two component among the three components.

14. A color image encoding apparatus using residue transform for encoding an original color image formed with at least two or more components, the apparatus comprising:

a spatiotemporal prediction unit for generating at least one for each component of the original color image, of a temporal predicted image by using the restored previous image and the current image, and a spatial predicted image by using a restored current image;

a residue generation unit for generating a spatial residue obtained by subtracting the spatial predicted image from the original image in a case of intra mode, and generating a temporal residue obtained by subtracting the temporal predicted image form the original image in a case of inter mode;

a residue transform unit for transforming the residue by using a relation between residues of respective components of the color image; and

a residue encoding unit for encoding the transformed residue, including at least quantization.

15. The apparatus of claim 14, further comprising:

an entropy coding unit for entropy coding the quantized data and generating a bitstream.

16. The apparatus of claim 14, wherein the spatiotemporal prediction unit comprises:

a spatial prediction unit for obtaining a predicted image of each component of the original color image in a case of intra mode, by estimating a prediction direction from restored pixels spatially adjacent to the pixel block of the current frame of each color component; and

a temporal prediction unit for obtaining a predicted image of each component of the original color image incase of inter mode, by estimating motions between the restored previous frame and the current frame of each color component in units of blocks of a predetermined size.

17. The apparatus of claim 14, wherein the predicted image of the spatiotemporal unit is generated by using an image which is restored by performing inverse quantization and inverse transform of a signal generated through transform and quantization in the residue encoding unit, and the performing prediction compensation.

18. A color image encoding apparatus using residue transform for encoding an original color image formed with at least two or more components, the apparatus comprising:

a residue generation unit for generating a residue corresponding to the difference of the original color image and a predicted image generated from a restored color image, for each component of the original color image;

a residue transform selection unit for selecting whether or not to perform residue transform by using a relation between the residues of the color image components generated in the residue generation unit;

a residue transform unit for transforming the residue by using the relation between residues of respective components of the color image if residue transform is selected in the residue transform selection unit; and

a residue encoding unit for encoding the residue transformed in the residue transform unit, or if residue transform is not selected in the residue transform unit, for encoding the residue generated in the residue generation unit, wherein the encoding includes at least quantization.

19. A non-transitory computer readable recording medium encoded with computer readable code comprising a program for implementing the method of any of claim 18.

20. A color image decoding method using residue transform for decoding an original color image formed with at least two or more encoded components, the method comprising:

restoring residue transformed image data by performing lossy decoding on the encoded data of the original color image;

generating the residue of each component of the color image by performing residue inverse transform of the residue transformed image data; and

restoring the original color image by adding a predicted image generated by using the restored image, to the residue of each component.

21. The method of claim 20, wherein the original image has any one of an R-G-B format, a Y-Cb-Cr format, and an X-Y-Z format.

22. The method of claim 20, wherein in the restoring of the original color image, in a case of intra mode, the original image is restored by compensating the residue of each color component for a value spatially predicted by using pixels spatially adjacent to the pixel block of a current image.

23. The method of claim 20, wherein in the restoring of the original color image, in a case of inter mode, the original image is restored by compensating the residue of each color component for a value temporally predicted by obtaining a predicted image from the previous image.

24. The method of claim 20, wherein in the restoring of the original color image, in a case of intra mode, the original image is restored by compensating the residue of each color component for a value spatially predicted by using pixels spatially adjacent to the pixel block of a current image;

and in a case of inter mode, the original image is restored by compensating the residue of each color component for a value temporally predicted by obtaining a predicted image from the previous image.

25. The method of claim 20, wherein assuming that three components of the color image are X₁, X₂, and X₃, and Δ

X₁, Δ

X₂, and Δ

X₃ are residues of X₁, X₂, and X₃, respectively, the residue inverse transform is performed by using the following equation;

26. The method of claim 20, wherein assuming that three components of the color image are X₁, X₂, and X₃, and Δ

X₁, Δ

X₂, and Δ

X₃ are residues of X₁, X₂, and X₃, respectively, the residue inverse transform is performed by using the following equation;

27. The method of claim 20, wherein assuming that three components of the color image are X₁, X₂, and X₃, and Δ

X₁, Δ

X₂, and Δ

X₃ are residues of X₁, X₂, and X₃, respectively, the residue inverse transform is performed by using the following equations;

t=Δ

²X₂−

(Δ

²X₃>

>

1)

Δ

X₁=Δ

²X₃+t

Δ

X₃=t−

(Δ

²X₁>

>

1)

Δ

X₂=Δ

X₃+Δ

²X₁

where Δ

²X₁, Δ

²X₂, and Δ

²X₃ are residue transformed signals.

28. The method of claim 20, further comprising:

entropy decoding an input bitstream of the original color image.

29. A color image decoding method using residue transform for decoding an original color image formed with at least two or more encoded components, the method comprising:

performing at least inverse quantization of the encoded data of the original color image;

determining whether or not the inverse quantized data is residue transformed;

if the data is residue transformed, performing residue inverse transform of the residue transformed image data and generating the residue of each component of the color image;

if the data is not residue transformed, generating the residue of each component of the color image from the inverse quantized data; and

restoring the original color image by adding a predicted image to the residue of each component.

30. A color image decoding apparatus using residue transform for decoding an original color image formed with at least two or more encoded components, the apparatus comprising:

a residue transform data restoration unit for restoring residue transformed image data from lossy encoded data of the original color image;

a residue inverse transform unit for performing residue inverse transform of the residue transformed data and generating the residue of each component of the color image; and

an original color image restoration unit for restoring the original color image by adding a predicted image generated by using a restored image, to the residue of each component.

31. The apparatus of claim 30, wherein the residue transform data restoration unit further comprises:

an entropy decoding unit for entropy decoding an encoded bitstream; and

an inverse quantization/inverse transform unit for performing inverse quantization and inverse transform of the entropy decoded data.

32. A color image decoding apparatus using residue transform comprising:

a lossy decoding unit for performing at least inverse quantization of a lossy encoded bitstream of a color image;

a residue transform determination unit for extracting residue transform selection information indicating whether or not residue transform is performed, from the data lossy decoded in the lossy decoding unit, and interpreting the information;

a residue transform data extraction unit for extracting residue transformed data from the lossy decoded data if the interpretation result of the residue transform selection information indicates that the lossy decoded data is residue transformed;

a residue inverse transform unit for performing residue inverse transform of the residue transformed data and generating the residue of each component of the color image;

a residue data extraction unit for extracting residue data from the lossy decoded data if the interpretation result of the residue transform selection information indicates that the lossy decoded data is not residue transformed; and

an original color image restoration unit for restoring the original color image by adding a predicted image generated by using a restored image, to the residue of each component.