METHOD FOR ENCODING/DECODING A QUANTIZATION COEFFICIENT, AND APPARATUS USING SAME
The present invention relates to a method for encoding/decoding a quantization coefficient, and to an apparatus using same. The decoding method can include the steps of: decoding initial quantization parameter information and quantization parameter range information of a slice; and obtaining a quantization parameter limitation range applied to an encoding unit included in the slice using the initial quantization parameter information and the quantization parameter range information. Accordingly, the efficiency of encoding and decoding an image can be improved during encoding/decoding.
1 . A decoding method comprising:
decoding initial quantization parameter information and quantization parameter range information on a slice; and
deriving a quantization parameter limit range applied to a coding unit comprised in the slice using the initial quantization parameter information and the quantization parameter range information on the slice.
2 . The decoding method of claim 1 , further comprising decoding basic quantization parameter information on the slice.
3 . The decoding method of claim 1 , wherein the initial quantization parameter information is a value obtained by adding changed slice quantization parameter information to basic quantization parameter information or subtracting the changed slice quantization parameter information from the basic quantization parameter information, or a value comprised in a slice header.
4 . The decoding method of claim 1 , wherein the quantization parameter limit range is from a value obtained by subtracting the quantization parameter range information from the initial quantization parameter information to a value obtained by adding the quantization parameter range information to the initial quantization parameter information.
5 . The decoding method of claim 1 , further comprising determining a variable-length code table based on the quantization parameter limit range of the coding unit and previous quantization parameter information on the coding unit and decoding a quantization parameter of the coding unit using the variable-length code table.
6 . The decoding method of claim 5 , wherein the previous quantization parameter information on the coding unit comprises at least one of quantization parameter information on a coding unit decoded before the coding unit, quantization parameter information on a left coding unit of the coding unit and the initial quantization parameter information on the slice.
7 . The decoding method of claim 5 , wherein the determining the variable-length code table based on the quantization parameter limit range of the coding unit and the previous quantization parameter information on the coding unit and decoding the quantization parameter of the coding unit using the variable-length code table comprises selecting a previously stored variable-length code table based on quantization parameter limit range and the previous quantization parameter information on the coding unit or creating a variable-length code table based on the quantization parameter limit range and the previous quantization parameter information on the coding unit.
8 . The decoding method of claim 1 , further comprising determining whether to change a quantization parameter value of the coding unit.
9 . The decoding method of claim 8 , wherein the determining whether to change the quantization parameter value of the coding unit comprises determining whether to change the quantization parameter value of the coding unit based on information on whether a quantization parameter of the coding unit is changed or depth information on a coding unit where a quantization parameter is changed.
10 . A decoding apparatus comprising:
an entropy decoding module to decode a quantization parameter variable; and
a dequantization module to derive a quantization parameter limit range applied to a coding unit comprised in a slice based on the quantization parameter variable decoded by the entropy decoding module.
11 . The decoding apparatus of claim 10 , wherein the dequantization module derives the quantization parameter limit range applied to the coding unit comprised in the slice using initial quantization parameter information and quantization parameter range information on the slice.
12 . The decoding apparatus of claim 10 , wherein the dequantization module determines a variable-length code table based on the quantization parameter limit range of the coding unit and previous quantization parameter information on the coding unit and performs dequantization based on a quantization parameter of the coding unit derived using the variable-length code table.
13 . The decoding apparatus of claim 12 , wherein the variable-length code table comprises a previously stored variable-length code table determined based on quantization parameter limit range and the previous quantization parameter information on the coding unit or a variable-length code table created based on the quantization parameter limit range and the previous quantization parameter information on the coding unit.
14 . The decoding apparatus of claim 10 , wherein the dequantization module comprises a quantization parameter derivation module to derive the quantization parameter limit range of the coding unit and previous quantization parameter information on the coding unit based on the quantization parameter variable provided from the entropy decoding module.
15 . The decoding apparatus of claim 14 , wherein the dequantization module further comprises a variable-length code table determination module to determine a variable-length code table for decoding a quantization parameter of the coding unit based on the quantization parameter limit range of the coding unit and previous quantization parameter information on the coding unit derived by the quantization parameter derivation module; and a dequantization implementation module to perform dequantization based on the variable-length code table determined by the variable-length code table determination module.