IIR Filter Coefficient Adjustment for Flicker Reduction in WDR Imaging
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Solution Overview
Problem
Existing wide dynamic range (WDR) image processing methods face challenges in preventing flicker artifacts and memory capacity increases when synthesizing short-exposed and long-exposed images, particularly in environments with moving objects and flickering light sources, leading to potential contour doubling and reduced WDR effects.
Innovation Solution
An image processing apparatus and method that employs an infinite impulse response (IIR) filter with a cyclic coefficient adjusted based on motion detection between long-exposed images in current and previous frames to perform filtering on short-exposed images, mitigating flicker and preventing contour doubling by adaptively setting the filtering coefficient according to detected motion values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If weighted-averaging of several images is performed to reduce flicker, then flicker is reduced, but frame memories are needed which increases memory size and data transmission load
Solution Approach 1:
The patent extracts only the necessary previous frame data (specifically long-exposed image data for motion detection) rather than storing multiple complete frames. This selective extraction reduces memory requirements while still enabling flicker reduction through IIR filtering.
Solution Approach 2:
The patent changes the parameter of memory storage from storing multiple complete frames to storing only essential motion detection data. This parameter change in data representation and storage requirements reduces the memory size needed for flicker mitigation.
2Object-affected harmful factors
If weighted-averaging of several images is performed to reduce flicker, then flicker is reduced, but contour doubling occurs for objects in motion
Solution Approach 1:
The patent applies dynamic adjustment of the IIR filter coefficient based on detected motion magnitude. When motion is detected, the coefficient is adjusted to reduce the influence of previous frames, preventing contour doubling while still reducing flicker for stationary regions.
Solution Approach 2:
The patent applies different processing characteristics to different regions based on motion detection. Regions with motion use one filtering strategy (with adjusted coefficients) while regions without motion use standard IIR filtering, achieving both flicker reduction and contour preservation locally.
3Object-affected harmful factors
If IIR filtering is applied to short-exposed images with fixed cyclic coefficient, then flicker is reduced, but WDR effect is compromised when objects are in motion
Solution Approach 1:
The patent uses motion detection feedback from long-exposed images to dynamically adjust the IIR filter coefficient. This feedback mechanism allows the system to adapt the filtering strength based on actual motion conditions, maintaining WDR quality while reducing flicker.
Solution Approach 2:
The patent transforms the fixed cyclic coefficient into a dynamic parameter that adjusts based on motion detection results. This dynamic adjustment ensures optimal balance between flicker reduction and WDR effect preservation under varying motion conditions.
Data Source
AI summary
Provided is an image processing apparatus and method. The image processing apparatus includes: a detection unit configured to detect a motion by using a long-exposed image in a current frame and a long-exposed image in a previous frame; and a processing unit configured to perform infinite impulse response (IIR) filtering on a short-exposed image in the current frame according to a result of the detecting of the motion which is obtained from the detection unit.