Method of removing deblocking artifacts

1. A method of processing a reconstructed picture, the method comprising:

generating a prediction block based on a prediction mode;

generating a quantization block by inverse-scanning quantization coefficient information;

generating a transform block by inverse-quantizing the quantization block using a quantization parameter;

generating a residual block by inverse-transforming the transform block;

generating a reconstructed picture by using the prediction block and the residual block; and

applying a deblocking filter on the reconstructed picture,

wherein it is determined whether the deblocking filtering is applied between two adjacent blocks P and Q containing samples p0 and q0 respectively by using a boundary quantization parameter when a boundary strength is not zero,

wherein the boundary quantization parameter is set to an average value of a quantization parameter of block P and a quantization parameter of block Q, and the quantization parameter is derived by adding a residual quantization parameter and a quantization parameter predictor,

wherein the quantization parameter predictor is derived per quantization unit which includes at least one coding unit,

when at least two of a left quantization parameter, an above quantization parameter and a previous quantization parameter are available, an average of two available quantization parameters selected in order of the left quantization parameter, the above quantization parameter and the previous quantization parameter is set as the quantization parameter predictor,

wherein the previous quantization parameter is set as the quantization parameter predictor when both of the left quantization parameter and the above quantization parameter are unavailable,

wherein the transform block is inversely transformed by using transform matrix determined according to a size of a transform unit.

2. The method of claim 1 , wherein a deblocking filter to be applied is selected by using the boundary quantization parameter.

3. The method of claim 1 , wherein the average of the two available quantization parameters is rounded off.