Real-Time Flicker Detection and Suppression in Video Sequences
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Solution Overview
Problem
Existing methods for detecting and suppressing image flicker in video sequences are inadequate, particularly in real-time applications over networks, as they are non-causal, computationally complex, and require buffering, which is unacceptable in internet communications.
Innovation Solution
A method that evaluates a variable based on the luminance of pixels at regular intervals, estimating the variation frequency and detecting undesired temporal luminance variations using a frame mean or weighted mean, which can be implemented in real-time with reduced computational complexity and hardware requirements, and includes a combined detection and suppression mechanism using cumulative distribution functions (CDFs) adapted for real-time video processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing CDF-based methods are used for flicker detection and suppression, then flicker suppression capability is improved, but computational complexity and hardware requirements increase significantly
Solution Approach 1:
The patent segments the flicker detection and suppression process into distinct functional blocks: a detection unit that analyzes luminance variations, a decision unit that determines flicker presence based on statistical criteria, and a suppression unit that applies CDF-based correction only when needed. This segmentation allows the system to maintain low computational complexity by avoiding unnecessary processing while preserving effective flicker suppression capability when detected.
Solution Approach 2:
The patent implements preliminary action by pre-computing and storing reference CDFs (cumulative distribution functions) from clean video frames before flicker occurs. These reference CDFs are used during real-time flicker suppression without requiring complex real-time computations, thus reducing hardware requirements while maintaining suppression effectiveness.
2Measurement precision
If buffering is implemented for flicker detection, then detection accuracy is improved, but real-time performance deteriorates
Solution Approach 1:
The patent uses preliminary action by pre-computing reference CDFs from clean video frames stored in a buffer before flicker detection is needed. This allows the real-time detection system to access pre-processed reference data without requiring continuous buffering during critical real-time operations, thus maintaining both detection accuracy and real-time performance.
Solution Approach 2:
The patent segments the video processing into different phases: a pre-processing phase where reference CDFs are computed and stored, and a real-time phase where detection and suppression occur using the pre-computed references. This temporal segmentation allows the system to achieve high detection accuracy through statistical analysis while maintaining real-time performance by avoiding computationally intensive operations during critical moments.
3Reliability
If complex flicker detection algorithms are applied, then detection capability is improved, but processing time increases
Solution Approach 1:
The patent applies preliminary action by pre-computing reference CDFs and statistical parameters from clean video frames before real-time detection is needed. This preliminary processing shifts the computational burden from real-time to offline processing, allowing the real-time detection system to use simple comparison operations against the pre-computed references, thus maintaining high detection capability while minimizing processing time during critical operations.
Solution Approach 2:
The patent uses copying by creating reference CDFs from clean video frames that serve as templates for detecting flicker. Instead of performing complex analysis on every incoming frame, the system copies the statistical characteristics from clean frames and compares new frames against these copies, significantly reducing real-time processing requirements while maintaining reliable detection capability.
Data Source
AI summary
The invention relates to a method, device and computer-program product for detection of undesired temporal variations (flicker) in a sequence of video frames. In one embodiment, frame-wise luminance means are compared with a reference level and the crossing frequency is compared with expected variation frequencies, such as frequencies associated with an illumination frequency through aliasing. The crossings count can be refined by introducing a latency zone around the reference level. In case of a positive detection of an undesired temporal variation, there is further provided a correction method, device and computer-program product using cumulated distribution functions. The visual detriment of flicker-induced saturation of pixels is alleviated either by brightening non-saturated pixels or by replacing the saturated pixels by randomly sampled values in accordance with a reference cumulated distribution function. The invention provides embodiments suitable for real-time processing of streamed video sequences.