Patent ID: 9584826
Date: 2017-02-28
CPC Classifications: H04N

Claim:
1. An image encoding apparatus, comprising: an intra predictor configured to generate a prediction block according to an intra prediction mode selected out of a plurality of intra prediction modes; a subtracter configured to generate a residual block by calculating a difference between the prediction block and an original block; a transformer configured to transform the residual block to generate a transform block; a quantizer configured to quantize the transform block using a quantization step size to generate a quantized transform block; a scanner configured to scan the quantized transform block to generate one-dimensional (1D) quantized coefficients; and an entropy coder 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 after the quantization of the transform block, wherein the scanner scans the plurality of sub-blocks using a first scan pattern determined according to the selected intra prediction mode and scans coefficients of each sub-block using a second scan pattern determined according to the selected intra prediction mode, wherein the first scan pattern is a scan order applied to the plurality of sub-blocks, and the second scan pattern is a scan order applied to the coefficients of each sub-block, wherein the first scan pattern is the same as the second scan pattern, wherein, when the selected intra prediction mode is a horizontal mode, the scan pattern is a vertical scan, and wherein the intra predictor includes: a reference pixel generator configured to generate reference pixels using available reference pixels of a current prediction block when reference pixels do not exist; a reference pixel filter configured to adaptively filter reference pixels adjacent to the current prediction block based on the selected intra prediction mode and size information of the current prediction block; and a prediction block generator configured to generate the prediction block of the current prediction block according to the selected intra prediction mode.