Image Decoding with Block-Size-Gated Secondary Inverse Transform
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Solution Overview
Problem
Existing image encoding/decoding methods face parsing delays and data buffering issues due to secondary transform information processing, especially for large coding blocks, leading to degraded subjective image quality and increased signaling overhead.
Innovation Solution
The method determines whether to apply secondary inverse transform based on the maximum transform block size and the current block's dimensions, avoiding secondary transform for large blocks and enabling efficient entropy encoding/decoding, thus reducing parsing delay and data buffering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If secondary transform is applied to large coding blocks, then signaling overhead is reduced, but subjective image quality is degraded and parsing delay increases
Solution Approach 1:
The patent applies different transform strategies to different regions: secondary transform is applied only to specific frequency domains (vertical or horizontal) rather than uniformly across the entire block, and only when block size conditions are met. This localized application maintains image quality in critical regions while reducing signaling overhead in appropriate scenarios.
Solution Approach 2:
The patent dynamically changes transform parameters based on block size and orientation. The secondary transform is conditionally applied based on comparing block dimensions against thresholds, and the choice between vertical or horizontal secondary transform depends on the aspect ratio and size characteristics of the coding block.
2Loss of information
If secondary transform is applied to large coding blocks, then signaling overhead is reduced, but parsing delay increases due to waiting for final split block processing
Solution Approach 1:
The patent performs preliminary determination of whether secondary transform should be applied based on block size information available early in the decoding process. By checking block dimensions against maximum transform block sizes before initiating transform operations, the system avoids waiting for final split block processing, thereby reducing parsing delay while still optimizing signaling overhead.
3Reliability
If data buffering is increased to store data for four times longer, then processing completeness is ensured, but device complexity and memory requirements increase
Solution Approach 1:
The patent extracts and processes transform information on a per-block basis rather than waiting for all split blocks to be processed. By taking out the necessary transform information early and processing it independently when block size conditions are satisfied, the system reduces the buffering period from four times longer to a minimal delay, thereby reducing device complexity and memory requirements while maintaining processing completeness.
Data Source
AI summary
Disclosed herein are an image encoding/decoding method and apparatus. The image decoding method of the present disclosure may include obtaining maximum transform block size information, deriving a maximum transform block size on the basis of the maximum transform block size information, and, determining whether or not a secondary inverse transform is applied to the current block on the basis of the maximum transform block size and a horizontal size and a vertical size of a current block.