Single Color Mode in Palette Video Coding
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Solution Overview
Problem
Conventional video coding techniques are inefficient for compressing computer-generated screen content, which often features discrete-tone and high contrast object boundaries, deviating from the assumptions of continuous-tone and spatial smoothness made in traditional video coding methods.
Innovation Solution
The implementation of palette-based coding, where a block of video data with a single color value is encoded using a single color mode as a sub-mode of the palette coding mode, reducing the number of bits required by generating a palette with a single palette entry indicating the single color value and signaling this in the encoded bitstream.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional video coding techniques are used for screen content, then the coding process follows standard procedures, but the compression efficiency is poor due to the discrete-tone and high contrast characteristics of screen content
Solution Approach 1:
The patent changes the coding parameters by introducing a single color mode that detects and codes blocks with uniform color values differently from conventional methods. When a block is identified as having a single color value, the encoder sets a single color mode flag and codes only the palette index and color value, rather than using standard transformation and quantization processes. This parameter change adapts the coding strategy to match the discrete-tone characteristics of screen content, significantly improving compression efficiency while preserving visual quality.
2Quantity of substance
If palette-based coding is used for blocks with single color value, then the number of bits required is reduced, but the complexity of the coding process increases due to additional mode detection and palette management
Solution Approach 1:
The patent segments the coding process into distinct modes by introducing a single color mode flag that divides blocks into two categories: those with single color values and those with multiple color values. This segmentation allows the encoder to apply simplified coding procedures only to uniform blocks, reducing the average bit rate. The segmentation is implemented through straightforward detection logic that checks color value uniformity within each block, adding minimal computational complexity while achieving significant bit rate reduction.
Solution Approach 2:
The patent applies partial action by implementing the single color mode only for blocks that meet the uniform color criterion, rather than applying a complex coding scheme to all blocks. The encoder performs a simple uniformity check and applies the simplified single-color coding procedure only when appropriate, leaving conventional coding methods for more complex blocks. This selective application reduces overall complexity while capturing the benefits of specialized coding for suitable content.
3Stability of the object's composition
If traditional palette coding mode is used for single color blocks, then the coding framework is maintained, but unnecessary bits are transmitted for palette information that could be inferred
Solution Approach 1:
The patent extracts and transmits only the essential information for single color blocks by setting the single color mode flag and transmitting only the palette index and color value. When the single color mode is detected, the encoder omits transmission of full palette information that would otherwise be required in conventional palette mode. The decoder, upon detecting the single color mode flag, infers the palette information from the transmitted palette index and color value, eliminating redundant bit transmission while maintaining coding framework consistency.
Data Source
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AI summary
Techniques are described for palette-based video coding. In palette-based coding, a video coder may form a "palette" as a table of colors for representing video data of a particular area. Rather than coding actual pixel values (or their residuals), the video coder may code palette index values for one or more of the pixels that correspond to entries in the palette representing the colors of the pixels. A palette may be explicitly encoded, predicted from previous palette entries, or a combination thereof. In this disclosure, techniques are described for coding a block of video data that has a single color value using a single color mode as a sub-mode of a palette coding mode. The disclosed techniques enable a block having a single color value to be coded with a reduced number of bits compared to a normal mode of the palette coding mode.