Image decoding apparatus adaptively determining a scan pattern according to an intra prediction mode

Patent metadata

Field	Value
Publication number	US-RE48564-E
Application number	US-201916367741-A
Country	US
Kind code	E1
Filing date	Mar 28, 2019
Priority date	Jul 31, 2010
Publication date	May 18, 2021
Grant date	May 18, 2021

Abstract

Provided is an image decoding apparatus that restores a quantized transform block by inversely scanning 1D quantized coefficients, inversely quantizes the quantized transform block using a quantization step size, inversely transforms the transform block to generate a residual block, and generates a prediction block according to an intra prediction mode. When a size of the transform block is 8×8, the quantized transform block is divided into a plurality of sub-blocks, and the plurality of sub-blocks and coefficients of each sub-block are scanned using a same scan pattern determined according to the intra prediction mode. When the intra prediction mode is a horizontal mode, the scan pattern is a vertical scan.

First claim

The invention claimed is:

1. An image decoding apparatus, comprising:
an entropy decoder configured to restore an intra prediction mode and one-dimensional (1D) quantized coefficients;
an inverse scanner configured to inversely scan the 1D quantized coefficients to generate quantized transform coefficients;
an inverse quantizer configured to inversely quantize a quantized transform block using a quantization step size to generate a transform block;
an inverse transformer configured to inversely transform the transform block to generate a residual block;
an intra predictor configured to generate a prediction block corresponding to a current prediction block according to the intra prediction mode; and
an adder configured to restore an original block by adding the residual block and the prediction block,
wherein the inverse scanner restores is further configured to restore a plurality of sub-blocks, which are generated by an encoder that divides the quantized transform block into the plurality of sub-blocks after quantizing the transform block when a size of the transform block is 8×8, by applying a first scan pattern determined according to the intra prediction mode to the 1D quantized coefficients, and restores restore the quantized transform block by applying a second scan pattern determined according to the intra prediction mode to the plurality of sub-blocks,
wherein the first scan pattern is a scan order applied to the 1D quantized coefficients, and the second scan pattern is a scan order applied to each sub-block of the plurality of sub-blocks determined according to the intra prediction mode,
wherein the first scan pattern is the same as the second scan pattern,
wherein, when the intra prediction mode is a horizontal mode, the second scan pattern is a vertical scan,
wherein a scan pattern for scanning flags indicating non-zero coefficients of each sub-block is the same as a scan pattern for scanning non-zero coefficients of each sub-block, and
wherein the intra predictor includes:
a reference pixel generator configured to generate reference pixels using available reference pixels of the 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 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 intra prediction mode.

2. The apparatus of claim 1 , wherein, when the intra prediction mode is one out of a predetermined number of intra prediction modes adjacent to the horizontal mode, the second scan pattern is the vertical scan.

3. The apparatus of claim 1 , wherein the restored plurality of sub-blocks are inversely scanned in a reverse direction.

4. The apparatus of claim 1 , wherein the quantization step size is determined per coding unit of a predetermined size.

Assignees

• M&K Holdings Inc

Inventors

• Oh Soo Mi
• Yang Moonock

Classifications

• H04N19/59 Primary

  involving spatial sub-sampling or interpolation, e.g. alteration of picture size or resolution · CPC title

• H04N19/82

  involving filtering within a prediction loop · CPC title

• H04N19/91

  Entropy coding, e.g. variable length coding [VLC] or arithmetic coding · CPC title

• H04N19/122

  Selection of transform size, e.g. 8x8 or 2x4x8 DCT; Selection of sub-band transforms of varying structure or type · CPC title

• H04N19/593 Primary

  involving spatial prediction techniques · CPC title