Journal ArticleDOI
Multispectral Filter-Wheel Cameras: Geometric Distortion Model and Compensation Algorithms
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TLDR
A mathematical model of the distortions of the optical path is derived and it is shown that the color fringes vanish completely after application of two different algorithms for compensation.Abstract:
Multispectral image acquisition considerably improves color accuracy in comparison to RGB technology. A common multispectral camera design concept features a filter-wheel consisting of six or more optical bandpass filters. By shifting the filters sequentially into the optical path, the electromagnetic spectrum is acquired through the channels, thus making an approximate reconstruction of the spectrum feasible. However, since the optical filters exhibit different thicknesses, refraction indices and may not be aligned in a perfectly coplanar manner, geometric distortions occur in each spectral channel: The reconstructed RGB images thus show rainbow-like color fringes. To compensate for these, we analyze the optical path and derive a mathematical model of the distortions. Based on this model we present two different algorithms for compensation and show that the color fringes vanish completely after application of our algorithms. We also evaluate our compensation algorithms in terms of accuracy and execution time.read more
Citations
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Patent
Systems and methods for non-contact heart rate sensing
Lalit Keshav Mestha,Beilei Xu +1 more
TL;DR: In this paper, a processing module can process multi-spectral video images of individuals and detect skin blobs within different images of the multiscale video images, which can then be converted into time series signals and processed with a band pass filter.
Patent
Rapid multi-spectral imaging methods and apparatus and applications for cancer detection and localization
Haishan Zeng,Fawzy Yasser +1 more
TL;DR: In this article, an iterative light transport based inversion algorithm was applied for correcting the intensity of the spectral images from the geometry/coupling effect as well as from the scattering amplitude distortions.
Journal ArticleDOI
Integration of 3D and multispectral data for cultural heritage applications: Survey and perspectives
TL;DR: The state of the art of such acquisition systems and their applications for the study of cultural heritage are presented and existing registration techniques that can be used to obtain 3D models with multispectral texture are described.
Proceedings ArticleDOI
Direct PSF Estimation Using a Random Noise Target
TL;DR: A new measurement method utilizing a random noise test target with markers is developed, which allows for direct comparison between prototype and image and presents comprehensive results for the PSF estimation using the authors' multispectral camera and provides deconvolution results.
Journal ArticleDOI
Normalized Total Gradient: A New Measure for Multispectral Image Registration.
TL;DR: In this article, a new measure called normalized total gradient is proposed for multispectral image registration, which is based on the assumption that the gradient of the difference between two aligned band images is sparser than that between two misaligned ones.
References
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Demosaicking: color filter array interpolation
TL;DR: The author begins by discussing the image formation process and examines the demosaicking methods in three groups: the first group consists of heuristic approaches, the second group formulates demosaicked as a restoration problem, and the third group is a generalization that uses the spectral filtering model given in Wandell.
Journal ArticleDOI
Color demosaicking via directional linear minimum mean square-error estimation
Lei Zhang,Xiaolin Wu +1 more
TL;DR: The experimental results show that the presented color demosaicking technique outperforms the existing methods both in PSNR measure and visual perception.
Journal ArticleDOI
Color image processing pipeline
TL;DR: An overview of the image processing pipeline is presented, first from a signal processing perspective and later from an implementation perspective, along with the tradeoffs involved.
Journal ArticleDOI
Interpolation Artefacts in Mutual Information-Based Image Registration
TL;DR: It is shown how the registration function depends on the interpolation method and how a slight resampling of one of the images may drastically improve the smoothness of this function.
Journal ArticleDOI
Interpolation artifacts in multimodality image registration based on maximization of mutual information
TL;DR: Several strategies reduced artifacts and improved registration robustness: JIT, BLUR, avoiding an extreme number of intensity bins, and resampling the images in a rotated orientation with different relative voxel sizes.