Residual Signal Filtering for Blocking Artifact Reduction
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Solution Overview
Problem
Existing hybrid backward-compatible coding technologies struggle to produce high-quality reconstructed signals with minimal image artefacts, particularly due to block-based transformations at low resolutions that exacerbate blocking effects.
Innovation Solution
A method of encoding and decoding signals that involves filtering decoded residuals using a weighted mask to improve picture quality and reduce blocking effects, applied to decoded residuals rather than the encoded or reconstructed picture signal, and utilizing a deblocking filter to mitigate the effects of block-based transformations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If block-based transformations are applied at low resolutions, then coding efficiency is improved, but blocking effects and image artifacts are exacerbated
Solution Approach 1:
A filtering operation is introduced as an intermediary step between the block-based transformation and the final reconstructed signal. The filter processes the decoded residuals to smooth blocking effects before they are applied to the base stream, thereby maintaining coding efficiency while reducing visible artifacts in the output image.
2Manufacturing precision
If residuals are decoded and applied to enhance base stream, then picture quality is improved, but decoding complexity and processing time increase
Solution Approach 1:
The filtering operation is performed on the decoded residuals before they are applied to the base stream. This preliminary action smooths blocking effects in advance, reducing the need for more complex post-processing operations and potentially decreasing overall decoding time while maintaining high picture quality.
3Object-generated harmful factors
If filtering is applied to decoded residuals, then blocking artifacts are reduced, but processing complexity increases
Solution Approach 1:
The filter operates on the decoded residuals by applying a weighting mask that emphasizes border regions. This parameter change approach allows the filter to target specific areas where blocking artifacts are most prominent, reducing overall processing complexity compared to applying a full convolution filter across the entire image.
Data Source
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AI summary
According to aspects of the invention there is provided a method of encoding an input signal, the method comprising: producing a base encoded signal by feeding an encoder with a downsampled version of an input signal; producing a first residual signal by: obtaining a decoded version of the base encoded signal; and using a difference between the decoded version of the base encoded signal and the downsampled version of the input signal to produce a first residual signal; encoding the first residual signal to produce a first encoded residual signal; producing a second residual signal by: decoding the first encoded residual signal to produce a first decoded residual signal; filtering the first decoded residual signal to produce a filtered version of the first decoded residual signal; correcting the decoded version of the base encoded signal using the filtered version of the first decoded residual signal to create a corrected decoded version; upsampling the corrected decoded version; and using a difference between the corrected decoded signal and the input signal to produce the second residual signal; and encoding the second residual signal to produce a second encoded residual signal, wherein the base encoded signal, the first encoded residual signal and the second encoded residual signal comprise an encoding of the input signal. An encoder, decoder and computer readable media may also be provided.