Method and apparatus for entropy encoding/decoding

1. A method of entropy encoding a plurality of current coefficients of a quality layer among a plurality of quality layers of an image block divided into the plurality of quality layers, the method comprising:

determining a coding pass with respect to each of the current coefficients;

a context model among a plurality of context models with respect to each of the current coefficients using an adjacent lower coefficient of an adjacent lower layer corresponding to a respective one of the current coefficients, wherein the context model is determined independently of coefficients of lower layers other than the adjacent lower layer; and

encoding a group of coefficients having a same selected context model among the current coefficients using the selected context model,

wherein the plurality of quality layers are layered in succession on top of one another, and the plurality of quality layers comprise a plurality of lower layers which are lower than the quality layer, and

the adjacent lower layer is one of the plurality of layers and is adjacently below the quality layer.

2. The method of claim 1 , wherein the plurality of quality layers comprise one discrete layer and a plurality of fine granular scalability layers.

3. The method of claim 1 , wherein the coding pass is determined according to whether all lower coefficients corresponding to each of the current coefficients are zero.

4. The method of claim 1 , wherein the coding pass is determined according to whether the adjacent lower coefficient of the adjacent lower layer corresponding to each of the current coefficients is zero, wherein the coding pass is determined independently of coefficients of lower layers other than the adjacent lower layer.

5. The method of claim 1 , wherein the at least one lower coefficient is an adjacent lower coefficient corresponding to each of the current coefficients.

6. The method of claim 5 , wherein a value of the adjacent lower coefficient is 1, 0 or −1, and three candidate models exist for the context model.

7. The method of claim 5 , wherein a value of the adjacent lower coefficient is 1 or −1, and two candidate models exist for the context model.

8. A method of entropy decoding a plurality of encoded current coefficients of a quality layer among a plurality of quality layers of an image block divided into the plurality of quality layers, the method comprising:

determining a coding pass with respect to each of the encoded current coefficients;

selecting a context model among a plurality of context models with respect to each of the encoded current coefficients using an adjacent lower coefficient of an adjacent lower layer corresponding to a respective one of the encoded current coefficients if the coding pass is a refinement pass, wherein the context model is determined independently of coefficients of lower layers other than the adjacent lower layer; and

decoding a group of coefficients having a same selected context model among the encoded current coefficients using the same selected context model,

wherein the plurality of quality layers are layered in succession on top of one another, and the plurality of quality layers comprise a plurality of lower layers which are lower than the quality layer, and

the adjacent lower layer is one of the plurality of layers and is adjacently below the quality layer.

9. The method of claim 8 , wherein the plurality of quality layers comprise one discrete layer and a plurality of FGS layers.

10. The method of claim 8 , wherein the coding pass is determined according to whether all lower coefficients corresponding to each of the encoded current coefficients are zero.

11. The method of claim 8 , wherein the coding pass is determined according to whether the adjacent lower coefficient of the adjacent lower layer corresponding to each of the encoded current coefficients is zero, wherein the coding pass is determined independently of coefficients of lower layers other than the adjacent lower layer.

12. The method of claim 8 , wherein the at least one lower coefficient is an adjacent lower coefficient corresponding to each of the encoded current coefficients.

13. The method of claim 12 , wherein a value of the adjacent lower coefficient is 1, 0 or −1, and three candidate models exist for the context model.

14. The method of claim 12 , wherein a value of the adjacent lower coefficient is 1 or −1, and two candidate models exist for the context model.

15. A method of entropy encoding a plurality of current coefficients of a quality layer among a plurality of quality layers of an image block divided into the plurality of quality layers, the method comprising;

determining a coding pass with respect to each of the current coefficients;

selecting a variable length coding (VLC) table among a plurality VLC tables with respect to the current coefficients using an adjacent lower coefficient of an adjacent lower layer corresponding to a respective one of the current coefficients, wherein the VLC table is determined independently of coefficients of lower layers other than the adjacent lower layer; and

performing a variable length encoding process on a group of coefficients having a same selected context model among the current coefficients using the selected VLC table,

wherein the plurality of quality layers are layered in succession on top of one another, and the plurality of quality layers comprise a plurality of lower layers which are lower than the quality layer, and

the adjacent lower layer is one of the plurality of layers and is adjacently below the quality layer.

16. The method of claim 15 , wherein the coding pass is determined according to whether all lower coefficients corresponding to each of the current coefficients are zero.

17. The method of claim 15 , wherein the coding pass is determined according to whether the adjacent lower coefficient of the adjacent lower layer corresponding to each of the current coefficients is zero, wherein the coding pass is determined independently of coefficients of lower layers other than the adjacent lower layer.

18. The method of claim 15 , wherein the at least one lower coefficient is an adjacent lower coefficient corresponding to each of the current coefficients.

19. A method of entropy decoding a plurality of encoded current coefficients of a quality layer among a plurality of quality layers of an image block divided into the plurality of quality layers, the method comprising:

determining a coding pass with respect to each of the encoded current coefficient;

selecting a variable length coding (VLC) table among a plurality of VLC tables with respect to each of the encoded current coefficients using an adjacent lower coefficient of an adjacent lower layer corresponding to a respective one of the encoded current coefficients, wherein the VLC table is determined independently of coefficients of lower layers other than the adjacent lower layer; and

performing variable length decoding on a group of coefficients having the same selected context model among the encoded current coefficients by using the selected VLC table,

wherein the plurality of quality layers are layered in succession on top of one another, and the plurality of quality layers comprise a plurality of lower layers which are lower than the quality layer, and

the adjacent lower layer is one of the plurality of layers and is adjacently below the quality layer.

20. The method of claim 19 , wherein the coding pass is determined according to whether all lower coefficients corresponding to each of the encoded current coefficients are zero.

21. The method of claim 19 , wherein the coding pass is determined according to whether the adjacent lower coefficient of the adjacent lower layer corresponding to each of the encoded current coefficients is zero, wherein the coding pass is determined independently of coefficients of lower layers other than the adjacent lower layer.

22. The method of claim 19 , wherein the at least one lower coefficient is an adjacent lower coefficient corresponding to each of the encoded current coefficients.

23. An apparatus for entropy encoding a plurality of current coefficients of a quality layer among a plurality of quality layers of an image block divided into the plurality of quality layers, the apparatus comprising:

a hardware processor;

a unit which determines a coding pass with respect to each of the current coefficients;

a unit which selects a context model among a plurality of context models with respect to each of the current coefficients using an adjacent lower coefficient of an adjacent lower layer corresponding to a respective one of the current coefficients, wherein the context model is determined independently of coefficients of lower layers other than the adjacent lower layer; and

a unit which performs arithmetic encoding on a group of coefficients having a same selected context model among the current coefficients using the selected context model,

wherein the plurality of quality layers are layered in succession on top of one another, and the plurality of quality layers comprise a plurality of lower layers which are lower than the quality layer, and

the adjacent lower layer is one of the plurality of layers and is adjacently below the quality layer.

24. An apparatus for entropy decoding a plurality of encoded current coefficients of in a layer among a plurality of quality layers of an image block divided into the plurality of quality layers, the apparatus comprising:

a hardware processor;

a unit which determines a coding pass with respect to each of the encoded current coefficients;

a unit which selects a context model among a plurality of context models with respect to each of the encoded current coefficients using an adjacent lower coefficient of an adjacent lower layer corresponding to a respective one of the encoded current coefficients, wherein the context model is determined independently of coefficients of lower layers other than the adjacent lower layer; and

a unit which performs arithmetic decoding on a group of coefficients having a same selected context model among the encoded current coefficients by using the selected context model,

wherein the plurality of quality layers are layered in succession on top of one another, and the plurality of quality layers comprise a plurality of lower layers which are lower than the quality layer, and

the adjacent lower layer is one of the plurality of layers and is adjacently below the quality layer.