Transform Coefficient Level Coding With Rice Lookup Tables
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Solution Overview
Problem
The increasing demand for high-resolution, high-quality images and videos, particularly in virtual reality and augmented reality, necessitates a more efficient compression technique to reduce transmission and storage costs while maintaining image quality.
Innovation Solution
A method and apparatus for enhancing video/image coding efficiency by improving residual coding efficiency through level coding for transform coefficients, utilizing rice parameter lookup tables and bin strings to derive level values from bitstreams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high resolution and high quality image/video are transmitted or stored, then image quality is improved, but transmission and storage costs are increased
Solution Approach 1:
The patent extracts and separately encodes the level value information of transform coefficients using a dedicated lookup table and Rice parameter derivation mechanism. This separation allows for more efficient coding of coefficient magnitudes independent of other transform parameters, reducing the overall bit rate required to maintain high image quality.
Solution Approach 2:
The patent dynamically selects Rice parameters from a lookup table based on the actual level value range of transform coefficients in each block. This adaptive selection optimizes the encoding efficiency for different content characteristics, allowing the system to maintain high quality while reducing the average bit rate across diverse video content.
2Productivity
If conventional coding methods are used for transform coefficients, then coding simplicity is maintained, but residual coding efficiency is insufficient
Solution Approach 1:
The patent pre-computes and stores optimal Rice parameter values in a lookup table before the actual video coding process. This preliminary preparation allows the encoder to quickly retrieve appropriate parameters during encoding without performing complex real-time calculations, thereby improving residual coding efficiency while minimizing the computational complexity during the actual coding operation.
Solution Approach 2:
The patent introduces a lookup table as an intermediary structure that maps transform coefficient level value ranges to optimal Rice parameters. This intermediary mechanism simplifies the coding process by replacing complex parameter selection algorithms with a straightforward table lookup operation, improving efficiency without significantly increasing implementation complexity.
3Adaptability or versatility
If mixed level values (low and high) are present in transform coefficients, then coding adaptability is improved, but coding performance in high bit rate environments is reduced
Solution Approach 1:
The patent applies different Rice parameters from the lookup table to different regions or blocks based on their local characteristics (low level values versus high level values). This local optimization ensures that each block is encoded with parameters best suited to its specific content characteristics, improving overall coding performance in high bit rate environments while maintaining the ability to handle mixed level value scenarios.
Data Source
AI summary
A video decoding method performed by a decoding apparatus according to the present document may comprise the steps of: obtaining, from a bitstream, information indicating a level value of a transform coefficient in a current block; selecting one Rice parameter look-up table for the information indicating the level value of the transform coefficient, from among a plurality of Rice parameter look-up tables; deriving a Rice parameter for the information indicating the level value of the transform coefficient on the basis of the selected Rice parameter look-up table; deriving a bin string for the information indicating the level value of the transform coefficient on the basis of the Rice parameter; and deriving the level value of the transform coefficient on the basis of the bin string.