NSST Residual Decoding for Lower Video Coding Rate

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Solution Overview

Problem

The increasing demand for high-resolution and high-quality images leads to a significant increase in the amount of information to be transmitted and stored, resulting in higher transmission and storage costs.

Innovation Solution

A video decoding method and apparatus utilizing Non-Separable Secondary Transform (NSST) to derive transform coefficients and residual samples, with the option to encode or not encode the NSST index based on specific conditions, reducing the bit amount required for NSST index transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If high-resolution and high-quality images are transmitted, then image quality is improved, but transmission cost increases

Engineering Contradiction:

Improveimage qualityVSAvoidtransmission cost

Core Design Contradiction:

Measurement precisionVSLoss of energy

Solution Approach 1:

The patent extracts and transmits only the essential residual information after prediction, rather than transmitting the complete high-resolution image data. By separating the prediction component from the residual component and only encoding the residual, the transmission cost is reduced while maintaining image quality reconstruction capability.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent transforms the image data from spatial domain to frequency domain using transform coding, and then applies quantization to change the precision parameters of different frequency components. Less important high-frequency components are quantized with lower precision, reducing the total bit rate while preserving perceptually important information.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If transform coefficients are fully encoded, then reconstruction accuracy is improved, but bit rate increases

Engineering Contradiction:

Improvereconstruction accuracyVSAvoidbit rate

Core Design Contradiction:

Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent applies different quantization precision levels to different regions and frequency components of the transform coefficients. Important low-frequency coefficients and locally important regions are encoded with higher precision, while less important high-frequency coefficients are encoded with lower precision or omitted entirely, achieving rate-distortion optimization.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent performs partial encoding of transform coefficients by selectively encoding only those coefficients that contribute significantly to reconstruction accuracy. Through thresholding and significance testing, many small-magnitude coefficients are omitted from encoding, reducing bit rate while maintaining acceptable reconstruction quality.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS12531988B2Image coding method on basis of non-separable secondary transform and device therefor

Publication Date: 2026.01.20 LG ELECTRONICS INC

AI summary

An image decoding method performed by means of a decoding device according to the present disclosure comprises the steps of: deriving transform coefficients of a target block from a bitstream; deriving a non-separable secondary transform (NSST) index with respect to the target block; performing inverse transform with respect to the transform coefficients of the target block on the basis of the NSST index and thus deriving residual samples of the target block; and generating a reconstructed picture on the basis of the residual samples.