Image Coding With Neighbor-Based Quantization Parameter Derivation
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Solution Overview
Problem
The increasing demand for high-resolution, high-quality images leads to higher transmission and storage costs due to increased information bits, necessitating a more efficient image compression technique.
Innovation Solution
A method and apparatus for enhancing video coding efficiency by deriving a quantization parameter (QP) based on neighboring samples, using a decoding apparatus with modules for entropy decoding, inverse quantization, prediction, and reconstruction to generate residual and prediction samples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-resolution, high-quality image data is transmitted or stored, then image quality is improved, but transmission cost and storage cost increase due to increased information bits
Solution Approach 1:
The patent changes the quantization parameter (QP) dynamically based on the gradient magnitude of neighboring blocks. By adjusting QP according to local image characteristics (smooth vs. detailed regions), the system achieves better compression efficiency while maintaining perceived image quality, thus reducing the quantity of information bits needed
2Device complexity
If a fixed quantization parameter is used for all blocks, then device complexity is reduced, but compression efficiency deteriorates due to inability to adapt to local image characteristics
Solution Approach 1:
The patent applies different quantization parameters to different blocks based on their local characteristics. By calculating gradient magnitudes and comparing them to thresholds, the system identifies smooth regions (using larger QP for better compression) versus detailed regions (using smaller QP for better quality), achieving adaptive compression without excessive complexity
Solution Approach 2:
The quantization parameter is changed dynamically based on local image characteristics. The patent derives QP values by comparing gradient magnitudes to thresholds and applying offset values, allowing the system to adapt compression strength to local content requirements, thereby improving compression efficiency
3Speed
If quantization parameter is derived without considering neighboring block characteristics, then processing speed is improved, but compression efficiency deteriorates
Solution Approach 1:
The patent performs preliminary calculations of gradient magnitudes for neighboring blocks before deriving the quantization parameter. By pre-computing these characteristics and storing them, the system can quickly determine appropriate QP values without repeated complex calculations, maintaining processing speed while improving compression efficiency
Solution Approach 2:
The quantization parameter derivation process uses information already available from neighboring blocks (gradient magnitudes, threshold comparisons) to determine optimal QP values. This self-service approach leverages existing data structures and calculations, avoiding additional processing overhead while improving compression performance
Data Source
AI summary
According to an embodiment of the present invention, a picture decoding method performed by a decoding apparatus is provided. The method comprises: decoding image information comprising information on a quantization parameter (QP), deriving an expected average luma value of a current block from neighboring available samples, deriving a quantization parameter offset (QP offset) for deriving a luma quantization parameter (luma QP) based on the expected average luma value and the information on the QP, deriving the luma QP based on the QP offset, performing an inverse quantization for a quantization group comprising the current block based on the derived luma QP, generating residual samples for the current block based on the inverse quantization, generating prediction samples for the current block based on the image information and generating reconstructed samples for the current block based on the residual samples for the current block and the prediction samples for the current block.