Escape Pixel Coding in Palette Video Compression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traditional video coding techniques are inefficient for compressing screen content with discrete-tone characteristics, such as text or computer graphics, as they assume continuous-tone and smooth images, leading to suboptimal compression performance.
Innovation Solution
The use of palette-based coding techniques, where a palette of dominant pixel values is created and index values are encoded instead of actual pixel values, with escape pixels being encoded using a combination of Golomb Rice and exponential Golomb coding with parameter 3, allowing for efficient compression of screen content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional video coding techniques are used for screen content, then the coding process is simple, but compression efficiency is poor
Solution Approach 1:
The patent segments the pixel value representation into two parts: a most significant portion and a least significant portion. The most significant portion is encoded using Golomb Rice coding while the least significant portion is encoded using exponential Golomb coding with parameter 3. This segmentation allows the encoder to handle different parts of the data with appropriate coding methods, improving overall compression efficiency for screen content while maintaining manageable coding complexity.
2Productivity
If encoder-dependent parameters and division operations are used for escape pixel coding, then coding flexibility is improved, but computational complexity and processing time increase
Solution Approach 1:
The patent extracts the most significant portion and least significant portion of escape pixel values as separate syntax elements. By separating these components, the encoding process can apply optimized coding methods to each portion independently, reducing the need for complex encoder-dependent parameters and division operations while improving encoding speed and reducing computational complexity.
Solution Approach 2:
The patent changes the parameter representation by using fixed parameter 3 for exponential Golomb coding of the least significant portion, rather than using variable encoder-dependent parameters. This parameter change eliminates the need for complex calculations and division operations, thereby improving encoding speed while reducing computational complexity.
3Productivity
If palette mode coding is used for screen content, then compression performance improves, but handling of escape pixels becomes more complex
Solution Approach 1:
The patent applies segmentation to escape pixel coding by dividing the escape pixel value into most significant and least significant portions. Each portion is then encoded using a simplified, dedicated coding method (Golomb Rice for the most significant portion, exponential Golomb with parameter 3 for the least significant portion). This segmentation reduces the complexity of handling escape pixels in palette mode while maintaining improved compression performance for screen content.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
In one example, a device includes a memory configured to store video data and a video decoder configured to decode an exponential Golomb codeword representative of at least a portion of a value for an escape pixel of a palette-mode coded block of video data, the video decoder is configured to decode the exponential Golomb codeword using exponential Golomb with parameter 3 decoding, and decode the block using the value for the escape pixel.