Intra Prediction Mode Selection via Gradient Analysis
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Solution Overview
Problem
Conventional video encoding standards face inefficiencies in reducing prediction mode information, leading to high bitrates and increased data transmission requirements, especially with emerging high-quality video services like 360° videos and HDR, which demand improved compression performance without degrading video quality.
Innovation Solution
A method for processing video frames by determining an application area of preceding pixel blocks, performing gradient analysis, and selecting an intra prediction video coding mode based on computed gradients to optimize encoding and decoding processes, allowing for autonomous selection of intra prediction modes at both the encoder and decoder, thereby reducing the need for explicit mode information in the bitstream.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If conventional video encoding standards are used with explicit mode information in bitstream, then prediction accuracy is maintained, but bitrate increases and compression efficiency decreases
Solution Approach 1:
The patent extracts the prediction mode information from the bitstream by performing gradient analysis directly at the decoder side. The decoder autonomously determines the intra prediction mode by analyzing gradient values of pixels in the current block, eliminating the need to transmit explicit mode information. This extraction approach reduces bitrate while maintaining prediction accuracy.
Solution Approach 2:
The decoder performs self-service by autonomously selecting prediction modes through gradient analysis without relying on encoder-transmitted mode information. The system uses local gradient computations and template matching to independently determine the optimal prediction mode, making the encoding process self-sufficient at the decoder side.
2Productivity
If gradient analysis and autonomous mode selection are implemented, then bitrate is reduced and compression efficiency improves, but computational complexity increases
Solution Approach 1:
The patent segments the gradient analysis process into distinct stages: computing gradient values for pixels, identifying significant gradients, performing template matching with reference blocks, and selecting prediction modes. This segmentation allows for optimized implementation of each stage, balancing computational load and reducing overall complexity.
Solution Approach 2:
The patent applies partial action by performing gradient analysis only on selected pixels rather than all pixels in the block. It uses excessive action by computing multiple gradient directions and performing comprehensive template matching to ensure accurate mode selection, then prunes the search space to reduce computational burden.
3Measurement precision
If intra prediction modes are selected based on gradient analysis, then prediction accuracy improves, but processing time increases
Solution Approach 1:
The patent performs preliminary gradient computation and identification of significant gradients before the actual mode selection process. By pre-processing the gradient information and identifying candidate regions, the system reduces the time required for subsequent template matching and final mode determination, thus improving processing efficiency while maintaining accuracy.
Solution Approach 2:
The patent applies local quality by performing detailed gradient analysis and template matching only in regions where gradients indicate significant variations. In homogeneous regions with low gradients, the system uses simpler prediction methods, thus allocating computational resources efficiently and reducing overall processing time while maintaining high prediction accuracy where needed.
Data Source
AI summary
A method of processing an image divided into a plurality of pixel blocks which are processed according to a processing sequence is provided, which comprises, for a current pixel block: determining an application area consisting of a set of pixels in blocks preceding the current block in the processing sequence, for each pixel of the application area, computing a gradient representing a directional change of an intensity at the pixel, and selecting, based on at least one of the computed gradients, an intra prediction video coding mode among a plurality of intra prediction video coding modes usable for encoding and/or decoding the current block.