Adaptive Intra Prediction Filtering for Video Encoding
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Solution Overview
Problem
Conventional image encoding devices face challenges in reducing prediction errors, especially when dealing with block sizes other than 8×8 pixels, due to limited smoothing processes and mismatched prediction modes, leading to inefficiencies and discontinuities at block boundaries.
Innovation Solution
An image encoding device that selects and applies filters based on various parameters such as block size, quantization parameters, and intra prediction modes to adaptively filter prediction images, reducing local prediction errors and improving image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single smoothing process is applied to all blocks, then the device complexity is reduced, but the prediction precision deteriorates for blocks with different characteristics
Solution Approach 1:
The patent applies different smoothing processes to different blocks based on their specific characteristics such as block size, prediction mode, and gradient information. Each block receives a customized smoothing treatment rather than a uniform approach, thereby improving prediction precision for diverse block types while maintaining manageable device complexity through systematic classification.
Solution Approach 2:
The patent dynamically selects smoothing parameters and processes based on real-time analysis of block characteristics including size, prediction mode, and gradient calculations. This dynamic adaptation allows the system to optimize prediction precision for each block while avoiding the complexity of pre-configuring multiple fixed smoothing processes for every possible block type.
2Productivity
If directional prediction modes are used, then the prediction efficiency increases when edges align with prediction directions, but prediction errors increase when edges are slightly distorted or displaced
Solution Approach 1:
The patent changes the smoothing parameters based on the prediction mode and block characteristics. For directional prediction modes, the smoothing process is adapted to the specific direction and strength, allowing the system to maintain high prediction efficiency when edges align with prediction directions while reducing errors when edges are distorted or displaced through adaptive parameter adjustment.
Solution Approach 2:
The patent calculates gradient information and uses it as feedback to determine the appropriate smoothing process. By analyzing the actual edge characteristics and comparing them with the prediction direction, the system can adjust the smoothing intensity and type to compensate for mismatches, thereby maintaining both prediction efficiency and accuracy.
3Device complexity
If average prediction is used, then the device complexity is reduced, but discontinuities occur at block boundaries leading to reduced prediction accuracy
Solution Approach 1:
The patent applies different smoothing treatments to blocks using average prediction based on their location and characteristics. Specifically, blocks adjacent to each other may receive different smoothing processes to ensure continuity at boundaries, thereby reducing discontinuities while maintaining relatively simple device complexity through targeted rather than universal smoothing.
Data Source
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AI summary
When carrying out an intra-frame prediction process to generate an intra prediction image by using an already-encoded image signal in a frame, an intra prediction part 4 refers to a table for filter selection to select a filter from one or more filters which are prepared in advance according to the states of various parameters associated with the encoding of a target block to be filtered, and carries out a filtering process on the prediction image by using the filter. As a result, prediction errors locally occurring can be reduced, and the image quality can be improved.