Digital Image Noise Removal via Sensor Movement and Median Combination
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Solution Overview
Problem
Conventional methods for removing fixed pattern noise from digital images, such as frame subtraction, require additional time for capturing dark frames and subsequent processing, resulting in prolonged total photographing time.
Innovation Solution
A digital image processing apparatus that physically moves a photoelectric converter between successive captures of light, creating multiple image frames which are then median combined to remove fixed pattern noise, eliminating the need for dark frame photography and reducing overall processing time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If frame subtraction method is used to remove fixed pattern noise, then noise removal effectiveness is improved, but total photographing time is prolonged
Solution Approach 1:
The patent applies preliminary action by capturing multiple image frames simultaneously with the CCD sensor before any noise removal processing occurs. By pre-capturing N frames (where N is an odd number) during the same exposure period, the system prepares the necessary data for median filtering in advance, eliminating the need for separate dark frame capture and reducing total processing time while maintaining effective noise removal.
2Measurement precision
If dark frame photography is performed to accurately reproduce fixed pattern noise, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent uses copying by creating multiple copies of the same image scene captured simultaneously through the CCD sensor. Instead of requiring a separate dark frame photograph to copy the fixed pattern noise characteristics, the system captures N copies of the actual image frames during normal operation. The median filtering of these copies inherently reproduces and eliminates fixed pattern noise without requiring additional dark frame capture equipment or complex calibration procedures.
3Productivity
If multiple successive image frames are captured and median combined, then productivity is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies segmentation by dividing the image capture process into N separate simultaneous frame captures during a single exposure period. Each frame is captured independently by the CCD sensor, and the segmentation allows median filtering to be applied to each pixel position across the N frames. This segmentation approach improves productivity by parallelizing the noise sampling process while the positioning precision requirement is mitigated because all frames are captured simultaneously during the same exposure, minimizing drift effects.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces the total photographing time by integrating noise removal into the image capture process, while maintaining the removal of fixed pattern noise and dead pixels, resulting in a more efficient image processing workflow.
Implementation Method 1
a photoelectric converter that receives light from a subject to be photographed, captures the received light a plurality of successive times, physically moves between each successive capture of the received light such that the received light impacts on a different portion of the photoelectric converter with each successive capture, and converts the plurality of successive captures of received light into electrical signals that represent a plurality of respective image frames of the subject
Data Source
AI summary
An apparatus and method of removing fixed pattern noise in a digital image processing apparatus are provided. The apparatus includes a controlling unit adjusting a number of image frames of a same image photographed by an imaging device and an exposure time of a shutter, and controlling a movement direction of the imaging device, which photographs the image; and a signal processing unit which median-combines the image frames of the same image photographed by the imaging device during the adjusted exposure time after moving the imaging device. The total photographing time is reduced by skipping a process of photographing a dark image and fixed pattern noise can be effectively removed by median-combining the image frames photographed while physically moving the imaging device between the photographing of consecutive image frames to remove the fixed pattern noise.