Intra-prediction Encoding Using Closer Reference Pixels
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Solution Overview
Problem
Intra-prediction in HEVC faces inefficiencies due to increased prediction block sizes, leading to decreased prediction residual energy, especially when predicting pixels farther from the decoded reference pixel, resulting in lower subjective image quality and coding efficiency.
Innovation Solution
An intra-prediction encoding method that uses a closer decoded pixel by determining a correction range and weight coefficient based on the prediction mode, correcting the prediction signal to reduce prediction residual energy, and transmitting correction information for decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If prediction block size is increased in HEVC, then coding efficiency is improved, but prediction residual energy decreases especially for pixels far from decoded reference pixel
Solution Approach 1:
The patent applies local quality by differentiating the treatment of pixels based on their distance from the decoded reference pixel. For pixels far from the reference pixel, the invention uses alternative reference pixels or adjusts prediction parameters to maintain prediction accuracy, thereby reducing prediction residual energy in those specific regions while preserving the overall coding efficiency benefits of larger block sizes.
Solution Approach 2:
The patent implements dynamics by making the prediction process adaptive based on pixel position and prediction mode. The system dynamically selects reference pixels and adjusts prediction parameters according to the specific characteristics of each pixel location within the block, allowing optimal prediction for both near and far pixels without compromising the efficiency gains from increased block size.
2Productivity
If prediction block size is increased, then coding efficiency is improved, but subjective image quality decreases
Solution Approach 1:
The patent maintains subjective image quality by applying different prediction strategies to different regions. For pixels far from the decoded reference pixel in large blocks, the invention uses alternative reference pixels or adjusted prediction parameters to preserve local detail and texture quality, preventing the degradation that would otherwise occur with uniform large-block prediction.
Solution Approach 2:
The system dynamically adapts prediction parameters based on pixel position, prediction mode, and block size. This dynamic adjustment ensures that subjective image quality is maintained across different regions of the block, allowing large blocks to achieve both coding efficiency and quality preservation through position-dependent prediction optimization.
Data Source
AI summary
Setting a reference pixel signal from a decoded pixel signal in intra-prediction in which a prediction signal is generated in the same frame, acquiring prediction mode identification information that identifies an intra-prediction mode, generating a prediction signal based on the reference pixel signal and the prediction mode identification information, making a determination regarding correction of the prediction signal using a reference pixel having a shorter distance from a pixel that is a prediction target in the intra-prediction mode identified by the prediction mode identification information, and correcting the generated prediction signal according to a result of the determination are included in order to provide an image encoding method and an image decoding method capable of improving subjective image quality and coding efficiency using a closer decoded pixel in an intra-prediction process.