Temporal Dithering and Filtering for Video Contouring Artifacts
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Solution Overview
Problem
Existing video processing techniques fail to effectively reduce contouring artifacts caused by bit limiting, especially when displaying high-bit videos on lower-bit devices, and lack flexibility in adapting to varying output resolutions.
Innovation Solution
A temporal dithering manager applies temporal dithering at a preprocessing stage and temporal filtering at a post-processing stage to improve video quality, using dynamic dither patterns and filters like IIR and FIR to minimize artifacts and adapt to device resolutions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If simple truncation or rounding is applied to reduce bit depth, then device complexity is reduced, but contouring artifacts appear in areas with slow spatially varying brightness or color
Solution Approach 1:
The patent applies dithering at a preprocessing stage before truncation, rather than after. By adding a dither signal to the input signal before the truncation operation, the patent prevents contouring artifacts from forming in the first place, while keeping the overall processing complexity manageable through this staged approach
Solution Approach 2:
The patent introduces a dither signal as an intermediary element between the input signal and the truncation operation. This dither signal, generated from truncated low-order bits and processed through temporal dithering and filtering, acts as a mediator that prevents the direct formation of contouring artifacts during bit depth reduction
2Object-affected harmful factors
If temporal dithering with dynamic patterns is applied, then contouring artifacts are reduced, but processing time and computational cost increase
Solution Approach 1:
The patent changes the temporal parameter of the dither signal by applying temporal filtering (IIR or FIR filters) to the dither signal generated from truncated low-order bits. This temporal transformation reduces the flicker and static pattern visibility while maintaining artifact reduction, and the use of efficient filter implementations keeps processing time acceptable
Solution Approach 2:
The patent employs dynamic dither patterns that change over time through temporal filtering operations. Instead of static dither patterns, the temporal filtering creates dynamically varying patterns that reduce perceptual artifacts, while the system adapts to different motion conditions to optimize processing efficiency
3Reliability
If dithering is performed at display level for specific hardware, then compatibility with specific devices is improved, but adaptability to varying output resolutions is reduced
Solution Approach 1:
The patent performs dithering at an earlier stage in the video processing pipeline, before the signal is committed to a specific display format. The temporal dithering and filtering operations create a universally compatible processed signal that can be adapted to various output resolutions and display devices, making the dithering process multi-functional rather than device-specific
Solution Approach 2:
By applying temporal dithering and filtering at a preprocessing stage before format conversion or display output, the patent prepares the signal in advance for multiple possible output scenarios. This preliminary processing ensures compatibility across different devices while maintaining adaptability to varying resolutions, as the dithered signal can be subsequently formatted for different displays
Data Source
AI summary
A temporal dithering manager uses temporal dithering to reduce contouring artifacts due to bit limiting. The temporal dithering manager truncates low order bits of an input signal, creates a temporal dither signal based on the truncated low order bits and applies the temporally created dither signal to the truncated signal. A temporal filtering manager applies a temporal filter to the truncated signal, thereby improving the quality of the truncated signal. The temporal dithering can be applied at a preprocessing stage, and the temporal filtering at a post-processing stage.