CCSO Downsampling Filters for Lower Video Reconstruction Error
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Solution Overview
Problem
Existing video coding technologies face challenges in effectively reducing reconstruction errors in video data compression, particularly in handling cross-component offset filtering for color components, which affects image quality.
Innovation Solution
Implementing a cross-component offset filtering method that applies a downsampling filter to samples of a first color component to generate downsampled samples, which are then processed to determine an offset value added to a second color component, using filter coefficients and tap positions to adjust reconstruction values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If video compression is applied to reduce bandwidth and storage requirements, then data size is reduced, but reconstruction error increases
Solution Approach 1:
The patent applies loop filtering as a preliminary action after decoding to adjust and refine the reconstructed video data. By processing the reconstructed samples through filtering operations (including cross-component offset filtering) before further encoding or output, the system pre-corrects reconstruction errors to minimize their impact on final quality while maintaining compression benefits.
Solution Approach 2:
The patent implements feedback mechanisms through loop filtering that uses reconstructed samples from previous encoding cycles to adjust current reconstructions. The cross-component offset filtering uses chroma sample information to refine luma sample reconstructions, creating a feedback loop that continuously improves reconstruction accuracy without increasing the original compressed data size.
2Manufacturing precision
If cross-component offset filtering is applied to adjust color components, then image quality improves, but processing complexity increases
Solution Approach 1:
The patent applies local quality by implementing cross-component offset filtering that operates differently on different color components (luma and chroma) and different spatial locations. The filter uses context-specific offset values derived from neighboring samples, applying localized corrections rather than uniform processing, which improves image quality while keeping the complexity manageable through targeted operation.
Solution Approach 2:
The patent introduces intermediary offset values as mediators between the decoded color components. Instead of directly complex processing, the system computes offset values from neighboring samples that mediate the adjustment of current samples. These offset values simplify the overall process by breaking down the complex color component adjustment into manageable offset calculation and application steps.
3Productivity
If downsampling filter is applied to generate downsampled samples, then computational efficiency improves, but sample detail is reduced
Solution Approach 1:
The patent applies partial downsampling by selectively applying the downsampling filter only to specific color components and specific spatial regions where it provides the most benefit. Rather than uniformly downsampling all samples, the system applies the filter partially to chroma components and luma components where needed, maintaining computational efficiency while preserving critical sample details in key areas.
Data Source
AI summary
Various implementations described herein include methods and systems for coding video. In one aspect, a video bitstream includes a current image frame and a first syntax element for a cross-component sample offset (CCSO) mode. The first syntax element indicates whether to generate a first sample offset of a first color sample of the current image frame based on one or more luma samples. An electronic device identifies a first luma sample that is collocated with the first color sample and neighboring luma sample(s) s of the first luma sample. The first luma sample and the one neighboring luma sample(s) are downsampled to generate downsampled luma sample(s) for the CCSO mode. The electronic device determines the first sample offset of the first color sample based on the downsampled luma sample(s), and reconstructs the current image frame at least by adjusting the first color sample based on the first sample offset.