Blurring Privacy Masks Using Intra-Predicted Coding Units
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Solution Overview
Problem
Current video encoding methods for applying privacy masks in surveillance systems are inefficient, as they require significant computational resources and are limited by pixilation, which results in unappealing and restricted masking capabilities.
Innovation Solution
A method that uses intra-predicted coding units with transformed coefficients set to zero to create aesthetically pleasing blurred privacy masks, allowing for flexible coding unit sizes and automatic or user-defined selection, leveraging existing prediction stages to reduce computational demands and support various encoding formats.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If blurring is used for privacy masking, then aesthetic quality is improved, but computational resources required increase
Solution Approach 1:
The patent applies preliminary action by performing intra-prediction before final encoding, generating predicted coding units that are then zeroed out in transform domain. This pre-computed prediction data is reused for privacy masking, avoiding the need for separate blurring computations and reducing overall computational resources while maintaining aesthetic quality.
Solution Approach 2:
The patent changes parameters by operating in the transform domain rather than spatial domain, and by controlling the degree of blurring through quantization parameters and transform block sizes. This allows aesthetic quality to be adjusted through parameter tuning rather than computationally expensive filtering operations.
2Use of energy by moving object
If pixilation is used for privacy masking, then computational resources are reduced, but aesthetic quality deteriorates
Solution Approach 1:
The patent uses copying by replicating the predicted coding unit data across multiple transform blocks within the privacy mask region. Instead of computing separate blur values for each block, the same predicted data is copied and zeroed out uniformly, achieving computational efficiency while maintaining visual consistency and aesthetic quality.
3Use of energy by moving object
If pixilation with maximum size limit is used, then computational resources are reduced, but masking area flexibility is restricted
Solution Approach 1:
The patent applies segmentation by dividing the privacy mask region into multiple coding units that can be independently processed. This allows the masking area to be flexibly adjusted by including or excluding specific coding units, enabling adaptation to various masking area requirements while maintaining computational efficiency through systematic division of the region.
4Ease of manufacture
If conventional privacy masking is used, then implementation is simple, but frame synchronization accuracy deteriorates
Solution Approach 1:
The patent uses feedback by utilizing intra-prediction data that is inherently synchronized with the current frame being encoded. The prediction process naturally aligns with frame boundaries and timing, providing automatic frame synchronization feedback without requiring additional complex synchronization mechanisms, thus maintaining both simplicity and accuracy.
Data Source
AI summary
Methods and apparatus, including computer program products, implementing and using techniques for encoding a video sequence comprising a plurality of image frames, by an encoder are described. An image frame is received from a video stream. An input is received, which indicates one or more regions in the received image frame for which a privacy mask should be applied. The one or more regions are represented by one or more coding units. The image frame is encoded into an output frame, wherein image data in the one or more regions is replaced by intra-predicted coding units with transformed coefficients set to zero, the intra-predicted coding units are obtained from a prediction stage in the encoder.