Digital Image Noise Reduction via Multi-Exposure Color Balancing
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Solution Overview
Problem
Single frame auto white balancing algorithms in digital imaging devices introduce noise into images due to the amplification of the noise floor during color correction, especially when high correction factors are applied.
Innovation Solution
The implementation of a digital image processing system that captures multiple images with varying exposure times for each color component, allowing for the determination of optimal exposure times based on auto white balancing gain factors to minimize noise amplification and improve color balance accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If single frame auto white balancing algorithms are used to correct color balance, then color rendition is improved, but noise in the processed image increases due to amplification of the noise floor
Solution Approach 1:
The patent segments the image capture process by taking multiple individual frames for each color component (red, green, blue) separately with different exposure times, rather than processing a single frame. This segmentation allows selective combination of frames to achieve color balance while minimizing noise amplification.
Solution Approach 2:
The patent changes the exposure time parameter for each color component based on the determined correction factors. By adjusting exposure time inversely proportional to the correction factor magnitude, the system optimizes the signal-to-noise ratio for each color component while achieving the required color balance correction.
2Measurement precision
If high correction factors are applied during color correction, then color balance accuracy is improved, but noise amplification increases
Solution Approach 1:
The patent performs preliminary action by capturing multiple frames with different exposure times before the color correction step. By pre-capturing frames with optimized exposure times based on anticipated correction factors, the system prepares the data in a state that minimizes noise amplification during subsequent color correction.
Solution Approach 2:
The patent applies dynamic adjustment of exposure time for each color component based on the magnitude of correction factors. The exposure time is made dynamic and adaptive rather than fixed, allowing the system to optimize the balance between correction accuracy and noise minimization for each specific imaging condition.
Data Source
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AI summary
An apparatus for balancing the colour in a digital image, the apparatus being configured to: receive a first digital image having a first image exposure time, wherein the first digital image is of a digital image comprising a plurality of colour components; determine a colour balance factor for each of the plurality of colour components of the first digital image; and determine a further exposure time for at least one further digital image, wherein the further exposure time is dependent at least in part on the colour balance factor for a colour component associated with the at least one further digital image and the first image exposure time.