Motion Adaptive Video Cropping for Stabilization
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Solution Overview
Problem
Conventional video stabilization methods use a constant cropping factor, which reduces the field of view and does not adapt to changing motion in video frames, especially problematic in wide-angle applications where minimal cropping is desired.
Innovation Solution
A method and apparatus for determining the amount of motion in video frames and adaptively predicting a cropping factor to exclude portions of frames, allowing for smooth and intelligent adjustment of the cropping factor based on predicted motion, optimizing the field of view and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a constant cropping factor is used for video stabilization, then the stabilization effect is achieved, but the field of view is reduced
Solution Approach 1:
The patent applies dynamics by transitioning from a static, constant cropping factor to a dynamic, adaptive cropping factor that changes based on real-time motion analysis. The system continuously analyzes motion between frames and adjusts the cropping factor accordingly, allowing the cropping amount to vary over time rather than remaining fixed. This resolves the contradiction by enabling stabilization while minimizing unnecessary cropping when motion is low.
Solution Approach 2:
The patent implements parameter changes by modifying the cropping factor parameter based on motion characteristics. Instead of using a fixed cropping parameter, the system dynamically adjusts this parameter in response to detected motion levels, motion direction, and motion patterns. This allows the field of view to be preserved when possible while still achieving stabilization when needed.
2Reliability
If a constant cropping factor is applied to all frames, then video stabilization is maintained, but image quality deteriorates during low motion periods
Solution Approach 1:
The system dynamically changes the cropping factor parameter based on actual motion conditions. During low motion periods, the cropping factor is reduced or set to zero, preserving image quality. During high motion periods, the cropping factor increases to provide necessary stabilization. This adaptive parameter adjustment resolves the contradiction between maintaining stabilization reliability and preserving image quality.
Solution Approach 2:
The patent applies partial action by using cropping only to the extent necessary for stabilization. Instead of applying a fixed excessive crop to all frames, the system calculates the minimum required cropping based on actual motion, applying partial stabilization when motion is low and full stabilization when motion is high. This optimizes the balance between stabilization effectiveness and image quality preservation.
3Reliability
If the cropping factor is increased to stabilize shaky video, then stabilization improves, but the field of view is further reduced
Solution Approach 1:
The system dynamically adjusts the cropping factor based on the severity of motion detected in each frame or frame sequence. When video is shaky, the cropping factor increases to provide stabilization. When video is stable, the cropping factor decreases to preserve field of view. This dynamic adaptation resolves the contradiction by making cropping proportional to actual stabilization needs rather than applying a fixed reduction.
Solution Approach 2:
The patent implements feedback by continuously monitoring motion between frames and using this information to adjust the cropping factor in real-time. The motion analysis feedback loop allows the system to respond to changing motion conditions, increasing cropping only when and to the extent that stabilization is actually needed, thereby preserving field of view during stable periods.
Data Source
AI summary
Determining an amount of motion in a second frame of video with reference to a first frame of video. Adaptively predicting a cropping factor for the second frame in response to the determined amount of motion. The cropping factor specifies a portion of the second frame that is to be excluded from the second frame. The predicted cropping factor is adaptively changed for a successive plurality of frames by buffering the first frame to predict a desired cropping factor for the second frame, wherein the first frame occurs prior to the second frame.