Two-Dimensional Palette Coding for Screen Content
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Solution Overview
Problem
Existing video compression methods are inefficient for screen content, leading to poor compression performance and quality issues such as blurred curves and texts, due to their failure to fully characterize the features of screen content.
Innovation Solution
The use of a two-dimensional palette coding method that groups pixels into larger units, reduces spatial redundancy by employing run values, and predicts palette table entries from preceding units, thereby improving compression performance for screen content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional video compression methods are used for screen content, then general video compression is achieved, but compression performance is inefficient and picture quality deteriorates (blurred curves and texts)
Solution Approach 1:
The patent segments the screen content into multiple palette tables, where each palette table represents a specific region or characteristic of the screen content. This segmentation allows different compression strategies to be applied to different parts of the content, improving both compression efficiency and preserving visual quality by maintaining distinct color palettes for different regions.
Solution Approach 2:
The patent changes the parameter representation by using palette indices instead of direct color values. Each pixel is represented by an index into a palette table, which significantly reduces the number of bits needed to represent each pixel while maintaining the ability to reconstruct the original image with high fidelity, thus improving compression performance without sacrificing picture quality.
2Productivity
If block coding modes and transform are used for screen content encoding, then general video coding is achieved, but bandwidth consumption increases
Solution Approach 1:
The patent uses copying by referencing previously defined palette tables. Instead of encoding complete palette tables for every block, the encoder copies references to existing palette tables that can be reused, significantly reducing the bitrate required for encoding screen content while maintaining coding efficiency.
Solution Approach 2:
The patent performs preliminary action by pre-defining palette tables that capture the dominant colors and characteristics of screen content regions before actual encoding. These pre-defined palettes are then reused throughout the encoding process, reducing the computational complexity and bandwidth consumption during the main encoding phase.
Data Source
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AI summary
Video data, e.g., screen content video data may be palette coded. A palette table including one or more color indices may be produced. A color index may correspond to one color. A palette index map may be created that maps one or more pixels of the v ideo data to a color index in the palette table, or a color that may be explicitly coded. A. palette index map prediction data may be generated that includes data that indicates values in the palette index map associated with at least some portions of the video data that are generated in a traverse scan order in which a scan line is scanned in an opposite direction of a preceding parallel scan line.