Camera Hand Jitter Reduction via Digital Frame Alignment
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Solution Overview
Problem
Current digital camera systems in mobile devices face challenges in reducing hand jitter-induced blurriness, especially under low lighting conditions, as existing techniques either require mechanical gyroscopes or amplify noise when trying to compensate for camera movements.
Innovation Solution
A camera system that operates in both normal and hand jitter reduction modes by modifying exposure time and gain parameters, using a table-based approach to maintain an equivalent exposure time-gain product, allowing for efficient digital compensation of hand jitter without the need for separate hardware, even under low light conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If exposure time is increased to capture images under low lighting conditions, then image brightness is improved, but hand jitter-induced blurriness increases
Solution Approach 1:
The system performs preliminary stabilization by capturing multiple frames at shorter exposure times before the final image is formed. By pre-capturing multiple slightly different frames due to hand jitter and then digitally stabilizing them through alignment and averaging, the system eliminates the need to use a single long exposure that would be blurry, thus resolving the contradiction between brightness and sharpness
Solution Approach 2:
The system changes the parameter of exposure time from a single long exposure to multiple short exposures. By capturing multiple frames at reduced individual exposure times and then processing them digitally (aligning and averaging), the system achieves both sufficient overall brightness accumulation and reduced hand jitter blur, as each short frame is sharper while the combined result is bright enough
2Manufacturing precision
If mechanical gyroscopes are used to compensate for camera movements, then hand jitter reduction is improved, but device complexity increases
Solution Approach 1:
The system replaces the mechanical gyroscope stabilization system with a digital image processing approach. Instead of using mechanical sensors and actuators to physically counteract hand jitter, the system captures multiple frames and uses digital signal processing (frame alignment, motion estimation, and averaging) to achieve stabilization, thereby eliminating complex mechanical hardware while maintaining hand jitter compensation capability
Solution Approach 2:
The system creates multiple digital copies of the scene at different moments in time (multiple frames) and then processes these copies through digital alignment and averaging. This digital copying and processing approach replaces the need for mechanical copying through physical stabilization, reducing hardware complexity while achieving the same stabilization effect
3Manufacturing precision
If multiple frames are captured and processed to reduce hand jitter, then image quality is improved, but computational complexity increases
Solution Approach 1:
The system applies partial processing by focusing computational effort only on the necessary aspects of multiple frames - specifically motion estimation and alignment - rather than fully processing each frame independently. By using efficient algorithms that estimate motion between frames and apply corrective transformations, the system achieves quality improvement with reduced computational overhead compared to exhaustive frame-by-frame processing
Solution Approach 2:
The system merges multiple frames through digital averaging after alignment. By combining the information from multiple short-exposure frames into a single stabilized image through additive averaging, the system achieves both improved brightness (from accumulated photons) and reduced noise (through statistical averaging), while the merging process itself is computationally efficient compared to more complex multi-frame processing techniques
Data Source
AI summary
A camera system in normal mode and hand jitter reduction (hjr) mode may comprise generating a first exposure time-gain product by multiplying the normal mode exposure time with the normal mode gain. It may further comprise modifying the normal mode exposure time and gain and multiplying these modified parameters to generate a second exposure time-gain product for a hjr mode that reduces the difference between the first exposure time-gain product and the second exposure time-gain product. To reduce the difference the normal mode frame rate may also be modified. Operation of a camera in normal mode may be in response to a sensed light level being above a threshold. The hjr mode may be selected by the user while the camera is operating. The hjr mode may be used in response to a sensed light level being lower than the threshold.