Digital Smear Correction Using Reference Image Alignment
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Solution Overview
Problem
Existing digital camera systems struggle with smear correction, particularly due to hand motion during image capture, which worsens with longer exposure times needed for poor lighting conditions, and mechanical or electronic stabilizers do not adequately improve signal-to-noise ratio and are often bulky and expensive.
Innovation Solution
A method and system for detecting and correcting shift and rotation smears in digital images using spatial and temporal difference vectors, correlation, and de-smearing circuits that align and sum pixel values from reference and shifted images to compensate for camera motion, allowing for effective smear correction without the need for bulky stabilizers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If long exposure time is used to improve signal-to-noise ratio in poor lighting conditions, then image brightness is improved, but image smear increases due to hand motion
Solution Approach 1:
The patent applies preliminary action by capturing a reference image before the main image to establish a stable reference frame. This reference image is used to detect and correct smear in the main image through comparison, allowing long exposure times to be used for improved brightness without suffering from motion-induced smear degradation.
Solution Approach 2:
The patent implements feedback by comparing the main image with the reference image to detect smear patterns, then using this detection information to correct the main image. The correction process uses the reference image as a feedback source to restore the original image quality despite hand motion during exposure.
2Stability of the object's composition
If mechanical or electronic stabilizers are used to mitigate hand motion, then image stability is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces mechanical stabilizer systems with a software-based image processing approach. By using digital image comparison and correction algorithms, the system achieves smear compensation without requiring complex mechanical or electronic stabilizing hardware, thereby reducing device complexity and cost.
Solution Approach 2:
The patent creates a digital copy (reference image) of the scene before exposure, which is then used as a template for correcting the main image. This copying approach enables smear detection and correction through digital processing rather than mechanical intervention.
3Stability of the object's composition
If mechanical or electronic stabilizers are used to mitigate hand motion, then image stability is improved, but signal-to-noise ratio improvement is insufficient
Solution Approach 1:
By capturing a reference image before the main image, the system establishes a stable reference that can be used to detect and correct smear. This preliminary action enables the system to achieve both image stability and improved signal-to-noise ratio through digital correction rather than relying solely on physical stabilizers.
Solution Approach 2:
The comparison between reference and main images provides feedback information about smear patterns, which is then used to correct the main image. This feedback mechanism enables simultaneous improvement of both image stability and signal-to-noise ratio by removing motion-induced artifacts while preserving genuine image signal.
Data Source
AI summary
Methods and apparatus to measure small shifts and rotations of video images captured in short succession after a first reference video image is captured, and to add the sequence of captures while shifting or rotating back the shifted or rotated images, in order to improve the SNR in low light conditions.