Privacy Mask Encoding Using Camera Motion Vectors
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Solution Overview
Problem
Pixelated privacy masks in cameras with movable fields of view tend to oscillate or flicker, causing an unpleasant user experience due to noise changes during camera movement.
Innovation Solution
The method encodes pixel blocks within the privacy mask area as inter-coded blocks with a motion vector set equal to the camera movement and a residual set to zero, ensuring that pixel blocks remain copies of their reference blocks, thereby preventing flickering and noise-related brightness or color changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pixelated privacy masks are applied to images captured by cameras with movable fields of view, then privacy protection is achieved, but the masks oscillate or flicker during camera movement causing unpleasant user experience
Solution Approach 1:
The patent applies temporal smoothing by referencing previously decoded images to determine privacy mask areas before encoding current images. This preliminary action stabilizes the mask position across multiple frames, preventing flickering during camera movement while maintaining privacy protection.
Solution Approach 2:
The patent copies privacy mask area information from previously decoded reference images to current images. By using the privacy mask area from a previous frame as a reference, the system maintains consistent mask positioning across frames, eliminating oscillation and flicker effects during camera movement.
2Productivity
If standard inter-coding is used for pixel blocks in privacy mask areas during camera movement, then compression efficiency is maintained, but noise changes cause brightness or color changes in the masked areas
Solution Approach 1:
The patent applies different encoding strategies to different regions of the image. For pixel blocks within privacy mask areas, it uses a specialized encoding mode that copies reference blocks directly, while other regions use standard inter-coding. This local differentiation ensures consistency in masked areas without compromising overall encoding efficiency.
Solution Approach 2:
The patent segments the image into pixel blocks and further identifies which blocks fall within privacy mask areas. This segmentation allows independent handling of masked and non-masked regions, applying appropriate encoding methods to each segment to maintain both efficiency and visual stability.
Data Source
AI summary
Image encoding within a pixelated privacy mask area is adapted in order to reduce flickering during movement of a camera. Motion vectors are set equal to the movement of the camera, and residuals are set to zero, thereby encoding pixel blocks within the privacy mask area as copies of corresponding pixel blocks in a reference image.