HEVC Palette Mode Indexing for Screen Content
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The Palette mode in video coding, as part of the HEVC Range Extension, faces inefficiencies in encoding screen content video sequences, where traditional coding tools perform poorly due to unique statistical characteristics.
Innovation Solution
An improved Palette mode coding method that enhances encoding efficiency by transforming pixel values into a finite number of indexes from a palette, allowing for more effective prediction and residual coding, specifically optimized for screen content video sequences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional predictive encoding modes (INTRA/INTER) are used for screen content, then the encoding process is simple and well-established, but coding efficiency is poor due to unique statistical characteristics of screen content
Solution Approach 1:
The patent segments the coding process into distinct phases: palette construction phase (where unique colors are identified and organized into palettes) and residual encoding phase (where deviations from the palette are encoded). This segmentation allows the system to leverage the specific statistical characteristics of screen content while maintaining a manageable encoding structure.
Solution Approach 2:
The patent changes the fundamental parameter representation from direct pixel values to palette indices. By transforming the encoding domain from raw pixel data to discrete palette references, the system achieves better compression efficiency for screen content while the complexity is managed through systematic palette construction and residual encoding.
2Measurement precision
If palette mode is implemented with full palette transmission, then prediction accuracy is improved, but bitrate increases due to redundant information
Solution Approach 1:
The patent extracts and transmits only the essential palette information (unique color values and their indices) rather than transmitting complete pixel data. By taking out only the necessary palette definitions and using residual encoding for deviations, the system achieves accurate prediction while reducing redundant data transmission.
Solution Approach 2:
The patent discards redundant palette information by using predictive models that infer palette entries from context. The residual encoding recovers only the necessary corrections, effectively discarding unnecessary palette data while maintaining prediction accuracy through intelligent reconstruction.
3Productivity
If palette mode is used for screen content, then coding efficiency improves, but compatibility with existing video coding standards is reduced
Solution Approach 1:
The patent designs the palette mode to be universally applicable across different video coding standards by using standard-compatible syntax elements and processing frameworks. The palette construction and residual encoding mechanisms are designed to work within the existing HEVC architecture, enabling multi-standard compatibility while maintaining efficiency for screen content.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A method for determining encoding parameters for encoding indexes of a block of indexes used for encoding a coding unit of an image according to a palette, each index being related to one of the pixels forming the coding unit, the palette comprising a set of indexes associated to pixel values. The method comprises: - generating each index of the block of indexes related to the coding unit from the palette based on corresponding encoding parameters, and - if indexes of the block of indexes cannot be generated from the palette for at least one pixels of the coding unit, generating index values corresponding to escape values for replacing said indexes of the block of indexes which cannot be generated, wherein encoding parameters corresponding to an index are determined according to the spatial neighbourhood of said pixel regarding to an encoding order.