Method and apparatus of simplified luma-based chroma intra prediction

An intra-frame prediction and chroma technology, applied in the field of coding technology, can solve problems such as high computational complexity

Active Publication Date: 2015-03-25
MEDIATEK SINGAPORE PTE LTD SINGAPORE
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Problems solved by technology

Such large multipliers will introduce higher computational complexity

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  • Method and apparatus of simplified luma-based chroma intra prediction
  • Method and apparatus of simplified luma-based chroma intra prediction
  • Method and apparatus of simplified luma-based chroma intra prediction

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[0051] As mentioned above, the current LM model derivation is quite complicated. Some operations require higher algorithm precision, such as the a1s*lmDiv operation. Therefore, in one embodiment of the invention, the complexity of the a1s*lmDiv operation is reduced by incorporating in the a1s derivation the internal bit depth of the chroma signal processed during the video encoding process. For example, the shift operation for a1s in conjunction with one embodiment of the present invention becomes:

[0052] a1s=a1>>Max(0,Log2(abs(a1))–(BitDepth C –2)). (20)

[0053] In equation (20), use (BitDepth C -2) Replace the constant (ie 14) of equation (13). Accordingly, the number of bits of a1s is limited to the bit depth of the chroma signal (i.e., BitDepth C ) minus one plus a sign bit. Also, change lmDiv from (2^15+a2s / 2) / a2s to (2^(BitDepth C -1)+a2s / 2) / a2s. Therefore, when a2s is equal to 1, lmDiv will be less than (2^BitDepth C ). As mentioned earlier, according to th...

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Abstract

A method and apparatus for chroma intra prediction based on reconstructed luma pixels and chroma pixels are disclosed. The chroma intra prediction is based on a linear model of derived co-located current luma pixels of the current luma block scaled by a scaling factor. The scaling factor comprises a product term of a division factor and a scaled covariance-like value associated with neighboring reconstructed luma and chroma pixels of a current block. The division factor is related to a first data range divided with rounding by a scaled variance-like value associated with the neighboring reconstructed luma pixels of the current block. The scaled covariance-like value, the first data range, or both of the scaled covariance-like value and the first data range are dependent on the internal bit depth, with which the chroma signal is processed during video coding process, according to an embodiment of the present invention.

Description

[0001] cross reference [0002] The present invention claims the priority of the PCT patent application No. PCT / CN2012 / 074118 filed on April 16, 2012 and the title of the invention is "Improvements of Luma-based Chroma Intra Prediction", which is hereby cited and incorporated by reference The entire content of the patent application. technical field [0003] The present invention is related to video coding, and more specifically, the present invention is related to simplified chroma intra prediction based on reconstructed luma pixels and chroma pixels coding technology. Background technique [0004] Motion-compensated inter-frame coding has been widely used in various coding standards, such as MPEG-1 / 2 / 4 and H.261 / H.263 / H.264 / AVC. Compared with motion-compensated inter-frame coding, which can effectively reduce the bitrate of compressed video, intra-frame coding (intra coding) is used to compress regions with large motion or scene changes. In addition, intra-frame coding...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04N19/593H04N19/186H04N19/42
Inventor 朱莉安娜·徐国玫郭峋
Owner MEDIATEK SINGAPORE PTE LTD SINGAPORE
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