Image Encoding Transformation Coefficient Prediction
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Solution Overview
Problem
Current image compression methods, such as those used in MPEG-4 and H.264/AVC, face inefficiencies in encoding high-resolution video content due to limitations in predicting transformation coefficients in the frequency domain, particularly when neighboring blocks have different coefficients.
Innovation Solution
A method and apparatus for improving image compression efficiency by predicting transformation coefficients in the frequency domain, where only the difference between the predicted and actual coefficients is encoded, utilizing a hierarchical coding structure and various prediction modes to optimize encoding and decoding processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If transformation coefficients are encoded directly without prediction, then encoding is simple, but compression efficiency is poor
Solution Approach 1:
The patent applies preliminary action by performing prediction of transformation coefficients before encoding. The encoder predicts transformation coefficients of the current block using coefficients from neighboring blocks, and only encodes the difference between predicted and actual coefficients. This preliminary prediction step reduces the amount of data needing encoding, improving compression efficiency while managing complexity through systematic prediction modes.
2Productivity
If prediction is applied when neighboring blocks have similar coefficients, then compression efficiency improves, but prediction fails when blocks have different coefficients
Solution Approach 1:
The patent applies dynamics by making the prediction process adaptive based on image characteristics. The encoder determines prediction modes (vertical, horizontal, DC, or skip mode) based on the actual transformation coefficients of neighboring blocks. When neighboring blocks have similar coefficients, prediction modes are applied; when they differ significantly, the skip mode is used. This dynamic adaptation ensures prediction accuracy varies with local image content, improving overall compression efficiency while maintaining reliability.
Data Source
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AI summary
Methods and apparatuses for encoding and decoding an image. A transformation coefficient having a low frequency component to be predicted from among transformation coefficients of a transformation block is replaced with a predetermined value, an incomplete residual block is generated by inversely transforming the transformation block including the replaced transformation coefficient, and the transformation coefficient having the low frequency component is predicted by using values of the incomplete residual block.