Multispectral Skin Imaging Alignment Using Cross-Channel Motion Vectors
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Solution Overview
Problem
Existing methods for aligning image frames in multi-spectral imaging of human skin are hindered by the spectral variation of skin reflectance, leading to misalignment due to movement during sequential illumination with different wavelengths, which complicates image registration.
Innovation Solution
A method and apparatus that utilize a multi-channel imaging device with separate light detection channels for different spectral bands, calculating motion vectors from one channel to align frames in another, ensuring consistent alignment across frames using multi-spectral light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If sequential multi-spectral illumination is used to capture image frames at different wavelengths, then spectral information richness is improved, but subject movement during the scan causes misalignment between frames
Solution Approach 1:
The patent applies preliminary action by first capturing a reference frame at a reference wavelength, then using this reference frame to guide the capture and alignment of subsequent frames at different wavelengths. Motion vectors are calculated based on the reference frame before aligning other frames, ensuring that spectral information is captured while maintaining spatial coherence across wavelengths.
2Productivity
If simple alignment algorithms are used for non-varying illumination, then alignment speed is improved, but spectral variation of skin reflectance under multi-spectral light complicates image registration
Solution Approach 1:
The patent applies local quality by calculating motion vectors for different regions of the image frame independently. Instead of applying a single global transformation, the method computes local motion compensation based on reference frames, allowing different parts of the image to be aligned according to their specific motion characteristics, thus handling spectral variations effectively.
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
Effectively aligns image frames despite spectral variations, enabling accurate spectral analysis of skin properties by maintaining consistent spatial coordinates across different wavelengths.
Implementation Method 1
a multi-channel imaging device to obtain two or more sequences of image frames of the subject, wherein each sequence of image frames is obtained using a respective light detection channel of the multi-channel imaging device
Implementation Method 2
controlling one or more light sources to emit multi-spectral light to illuminate the subject, wherein the multi-spectral light comprises at least a first light component having a first illumination wavelength, and a second light component having a second illumination wavelength
Data Source
AI summary
According to an aspect, there is provided a method for aligning image frames in a sequence of image frames of a subject. The method comprises controlling (101) one or more light sources to emit multi-spectral light to illuminate the subject, wherein the multi-spectral light comprises at least a first light component having a first illumination wavelength, and a second light component having a second illumination wavelength; controlling (103) a multi-channel imaging device to obtain two or more sequences of image frames of the subject, wherein each sequence of image frames is obtained using a respective light detection channel of the multi-channel imaging device, wherein the multi-channel imaging device comprises a first light detection channel that is responsive to light in a first spectral band to generate a first sequence of frames of the subject, and a second light detection channel that is responsive to light in a second spectral band to generate respective a second sequence of frames of the subject, wherein the first illumination wavelength is within the first spectral band, and the second illumination wavelength is within the second spectral band; processing (105) the first sequence of frames to calculate motion vectors for each frame, wherein each motion vector represents a movement of the subject between frames in the first sequence; and aligning (107) the frames in the second sequence of frames according to the corresponding determined motion vectors such that the subject is aligned across the frames in the second sequence of frames.