Image Capture for Ambient Light Correction Under Object Motion
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Solution Overview
Problem
Images captured by cameras often introduce errors due to movement of the object between frames when ambient light correction is applied, making accurate comparison or color determination difficult.
Innovation Solution
A method involving capturing multiple primary images with varying illumination, performing ambient light correction on these images to generate ambient light corrected (ALC) images, and selecting the ALC image with the lowest error due to motion by comparing pixel intensity changes across pairs of ALC images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ambient light correction is applied by comparing pixels of captured images, then ambient light can be corrected to enable accurate comparison and color determination, but errors are introduced when there is movement of the object between frames
Solution Approach 1:
The patent applies preliminary action by capturing multiple images at different exposure times before the final comparison is made. By capturing a first image with a first exposure time and a second image with a second exposure time, the system prepares multiple versions of the same scene that can be selectively combined or compared to account for motion artifacts, thus improving reliability while maintaining measurement precision.
Solution Approach 2:
The patent utilizes parameter changes by varying the exposure time between the first image and the second image. This change in exposure parameter allows the system to capture different amounts of ambient light and controlled light, creating images that can be mathematically combined to eliminate ambient light effects while reducing motion-induced errors through the temporal separation of captures.
2Measurement precision
If multiple images are captured with varying illumination to perform ambient light correction, then color accuracy can be improved, but the time required for image capture and processing increases
Solution Approach 1:
The patent applies periodic action by capturing images at different exposure times in a systematic sequence. The first image is captured with a first exposure time and the second image with a second exposure time, creating a periodic pattern of illumination capture that enables ambient light correction. This structured approach allows for efficient processing while maintaining color accuracy.
Solution Approach 2:
The patent uses preliminary action by capturing the necessary images with varying illumination before the final color determination is made. By pre-capturing the first image and second image with different exposure times, the system prepares all necessary data for ambient light correction in advance, enabling accurate color determination without extending the critical processing time.
Data Source
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AI summary
:According to an aspect, there is provided a method for minimising error in ambient light corrected (ALC) images due to motion. The method comprises capturing a plurality of primary images of an object over a time window, with controlled illumination of the object varying over time, performing ambient light correction on at least a portion of the plurality of primary images to generate a plurality of ambient light corrected images, each ALC image being generated based on demodulating a sub-set of the plurality of primary images with differing controlled illumination, calculating an error value for pairs of ALC images, each pair of ALC images including a first ALC image and a second ALC image and comparing the error values for each pair of ALC images and selecting an error-minimised image from the pair of ALC images having the lowest error value within the time window Calculating the error value comprises comparing each pixel of the first ALC image with a corresponding pixel of the second ALC image, and determining a change in intensity for each pixel between the first ALC image and the second ALC image, and calculating an error value for the pair of ALC images based on the change in intensity over a plurality of pixels.