Apparatus for generating prediction block

An image codec apparatus, comprising:

• a transform unit configured to transform residual signals to generate a transform block;
• a quantization unit configured to quantize the transform block using a quantization step size to generate a quantized transform block;
• a scanning unit configured to scan the quantized transform block to generate one-dimensional (1D) quantized coefficients;
• an intra prediction unit configured to generate a prediction block according to an intra prediction mode selected out of a plurality of intra prediction modes;
• and
• an entropy coding unit configured to entropy-code the 1D quantized coefficients,
• wherein, when a size of the transform block is 8×8, the quantized transform block is divided into a plurality of sub-blocks,
• wherein the plurality of sub-blocks and coefficients of each sub-block are scanned using a scan pattern for scanning the plurality of sub-blocks and the coefficients of each sub-block, the scan pattern being determined according to the selected intra prediction mode,
• wherein, when the selected intra prediction mode is a horizontal mode, the scan pattern is a vertical scan, and
• wherein the intra prediction unit includes:
• a reference pixel generating unit configured to generate reference pixels using available reference pixels of a current block when reference pixels do not exist;
• a reference pixel filtering unit configured to adaptively filter reference pixels adjacent to the current block based on the selected intra prediction mode and size information of the current block;
• a prediction block generating unit configured to generate a prediction block of the current block according to the selected intra prediction mode;
• and
• a prediction block filtering unit configured to adaptively filter one or more prediction pixels of the prediction block based on the selected intra prediction mode and the size of the current block.