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High performance loop filters in video compression

A loop filter, filter technology, applied in the direction of digital video signal modification, electrical components, image communication, etc., can solve problems such as incomplete capture of non-uniform frames

Inactive Publication Date: 2015-03-18
THE CHINESE UNIVERSITY OF HONG KONG
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, block-based methods do not fully capture the local statistics of non-uniform frames

Method used

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  • High performance loop filters in video compression
  • High performance loop filters in video compression
  • High performance loop filters in video compression

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Experimental program
Comparison scheme
Effect test

Embodiment approach 1

[0051] Figure 4 A block diagram of the filter 100 according to the first embodiment of the present application is shown, and in the present application, the filter may refer to an NLK loop filter. Such as Figure 4 As shown, the NLK loop filter 100 includes a parameter estimation unit 10 , an NLK filter unit 20 and an inverse ICT unit 30 .

[0052] The parameter estimation unit 10 is configured to receive the pilot frame and then determine the mean value from the blocks of the pilot frame by equations (4) and (5) respectively. and variance Figure 5 shows the operation of obtaining the current residual block in the pilot frame and its turning to the residual block, where P m，n is with B m，n corresponding prediction block. R m，n , is the residual block.

[0053] As mentioned above, the pilot frame is retrieved from the encoding process using the QALF+DLF loop filter method.

[0054] NLK filter unit 20 is configured to receive each quantized residual coefficient y ...

Embodiment approach 2

[0063] A quadtree is a tree data structure in which each internal node has exactly four child nodes. Quadtrees are often used to quarter a two-dimensional space. Figure 6 An example of quadtree block division is shown. A quadtree-based block partition indication as described below means that the NLK or OCNLK filter is on or off for each block. Gray blocks are selected to use the filter according to an embodiment of the application, other blocks are not filtered. These block controls are encoded as side information by Context Adaptive Binary Arithmetic Coding (CABAC) and passed to the decoder. Block sizes can be 4, 8, 16, 32, 64 and 128. The decoder then determines whether to use the suggested filter after the passed block control is decoded.

[0064] Figure 7 A block diagram of a filter 200 according to the second embodiment of the present application is shown, and the filter 200 may be a quadtree-based NLK or OCNLK loop filter (QNLK or QOCNLK). Such as Figure 7 As s...

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Abstract

Disclosed are a filter and a method to improve the objective and subjective video coding performance The filter comprises: a parameter estimation unit configured to determine means and variances from a pilot frame; a filter unit configured to receive quantized residual coefficients in video coding process and restore coefficients from the quantized residual coefficients and the determined means and variances; an inverse ICT unit configured to apply an inverse ICT to the restored coefficients to obtain a filtered frame; a rate-distortion optimization unit configured to determine a quadtree block partition index; and an adaptive block selection unit configured to select final blocks according to quadtree block partition index, the final blocks being utilized to form the filtered frame.

Description

technical field [0001] This application relates to high performance loop filters for video compression. Background technique [0002] Due to the large data volume of images and videos, they are always expressed in compressed form when they are transmitted or stored. Block-based transform coding is widely used in image compression methods. First, an 8th-order DCT (order-8DCT) is used to compress the signal energy, and then, quantization is applied to the transform coefficients. Block-based transform coding is also widely used for video data that is first compressed by intra / inter prediction to further compress the signal energy. Then, quantization is performed on the residual transform coefficients of the video signal. Such video coding methods are often referred to as hybrid video coding due to their use of transform coding and predictive coding. Most video coding standards (including H.264 / AVC) use hybrid video coding. In image and video coding systems, quantization is...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04N19/82H04N19/61H04N19/147H04N19/96
CPCH04N19/82H04N19/176H04N19/619H04N19/117H04N19/46H04N19/96H04N19/147
Inventor 张任奇湛伟权
Owner THE CHINESE UNIVERSITY OF HONG KONG