Palette Mode Coding for Screen Content 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 smoothness, which are not applicable to screen content featuring sharp lines and high-contrast object boundaries.
Innovation Solution
The implementation of palette-based coding, where a palette of dominant pixel values is created to represent video data, with index values signaling pixel values instead of actual pixel values, allowing for efficient encoding and decoding of screen content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional video coding techniques are used, then continuous-tone video can be compressed, but screen content with discrete-tone characteristics cannot be efficiently compressed
Solution Approach 1:
The patent changes the fundamental parameter representation from continuous-tone pixel values to discrete palette indices. By transforming the video data representation from actual color values to indices referencing a limited palette, the coding technique adapts to the discrete-tone characteristics of screen content while maintaining compression efficiency.
Solution Approach 2:
The patent applies palette-based coding specifically to screen content regions rather than uniformly to all video content. By identifying and applying the discrete-tone optimization locally to appropriate content types, the system achieves high compression efficiency for screen content while preserving compatibility with traditional video coding for continuous-tone content.
2Loss of information
If actual pixel values are transmitted, then complete color information is preserved, but data volume increases
Solution Approach 1:
The patent creates a palette table that contains the actual color values, and then transmits only indices referencing this palette instead of the full pixel values. The receiver reconstructs the original image by copying color values from the palette using the transmitted indices, thereby preserving complete color information while dramatically reducing data volume.
Solution Approach 2:
The patent introduces a palette table as an intermediary structure between the source image and the transmitted data. This palette acts as a lookup table that maps discrete indices to actual color values, allowing the system to transmit compact index information while maintaining the ability to reconstruct full-color images at the receiver.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Receiving a plurality of syntax elements that are indicative of a palette that was used to encode a block of video data, the plurality of syntax elements including a first syntax element that indicates a number of palette values for the palette that are explicitly signaled in the encoded video bitstream, wherein the first syntax element is encoded using one or more Golomb codes such that the length of the encoded first syntax element is less than or equal to a predetermined maximum number of bits, decoding the plurality of syntax elements, including decoding the first syntax element using the one or more Golomb codes, reconstructing the palette based on the decoded plurality of syntax elements, and decoding the block of video data using the reconstructed palette.