Shutter Fluttering Sequence for Iris Biometric Motion Blur
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Solution Overview
Problem
Iris-based biometric systems face challenges in acquiring sharply-focused images from moving subjects, especially in low-light conditions, due to motion blur, which degrades image quality and destroys fine details essential for identification.
Innovation Solution
A method and system for determining an optimal shutter fluttering sequence that encodes information at all frequencies, using a two-step process to find the number and duration of open shutter periods and their arrangement, maximizing a fitness score based on Modulation Transfer Function and contrast attributes, while respecting hardware constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a traditional shutter is used with long exposure time to capture images in low-light conditions, then sufficient light is collected, but motion blur occurs which destroys fine details
Solution Approach 1:
The shutter is opened and closed periodically during the exposure period, creating a fluttering pattern. This periodic action allows the system to collect light over a long duration while the repeated opening and closing prevents motion blur by effectively resetting the exposure multiple times, thereby maintaining image sharpness while achieving sufficient light collection in low-light conditions
2Use of energy by moving object
If the shutter is kept open longer to capture moving subjects, then more light is collected, but motion blur increases and fine details are lost
Solution Approach 1:
By implementing periodic shutter opening and closing during the exposure period, the system maintains the ability to capture high-frequency spatial information. The periodic action effectively divides the long exposure into multiple shorter exposure intervals, preventing the accumulation of motion blur while still allowing sufficient total light collection over the extended exposure duration
3Manufacturing precision
If post-processing deblurring methods are applied to recover sharp images, then image sharpness improves, but sensor noise is severely amplified
Solution Approach 1:
The shutter fluttering pattern is designed in advance to inherently prevent motion blur during image capture. By optimizing the opening and closing timing of the shutter before image acquisition, the system prevents the need for aggressive post-processing deblurring operations that would amplify sensor noise, thereby maintaining image quality without introducing artificial noise
Data Source
AI summary
A method, system and computer-usable medium for determining shutter fluttering sequence. The disclosed approach is based on the use of shutter flutter technology, which means that an image can be acquired in such a manner as to encode all information about the moving subject. The disclosed approach involves determining a shutter's fluttering pattern that optimally encodes information at all frequencies. The disclosed approach involves an optimization method for finding a shutter fluttering pattern that has several desired properties. These properties can be expressed in the context of a fitness function: given a fluttering pattern and the target subject's velocity, it produces the equivalent Modulation Transfer Function (MTF), measures three attributes, and produces a fitness score. These attributes are the minimum contrast, the variance in contrast across spatial frequencies, and the mean contrast. The objective of the disclosed approach is to determine the fluttering pattern that maximizes the fitness score.