The spectral reflectance of multispectral images can provide more valuable information about object characteristics. In order to improve the utilization of the spectrum, the reflectance reconstruction requires the same system calibration and illumination of the image acquisition. Therefore, Khan proposed the concept of multispectral constancy, which is to transform the multispectral image data into a standard representation through spectral adaptive transformation. Khan used the linear mapping method to solve SAT to convert the multispectral image data obtained under unknown illumination into the image data under standard light source. In order to further improve the spectral utilization rate and expand the application range of multispectral cameras, an algorithm to improve multispectral constancy based on chromatic aberration index is proposed in this paper. The algorithm uses chromatic aberration as the objective function to solve the spectral adaptive transformation. In this paper, ten light sources are used as unknown light sources, SFU and X-rite are used as training and testing datasets, and multispectral camera channels are simulated by Equi-Gaussian and Equi-Energy filters with different number of channels to train and test 5, 6, 8, and 10 channels of data. In this paper, the color difference under different light sources is used as the evaluation index to test the performance of the proposed algorithm, and compared with the Khan method for calculating SAT multispectral constancy. The experimental results show that the spectral constancy algorithm based on color difference can perform better, and expand the application of different kinds of unknown light sources in multispectral constancy.
KEYWORDS: Picosecond phenomena, Cameras, Data modeling, Optical filters, Digital filtering, Reflectivity, Multispectral imaging, Reconstruction algorithms, Neural networks, RGB color model
Taking advantage of the technology of dispersive Fourier transform (DFT), we experimentally observed the evolutionary dynamics of convention solitons(CSs) in a simplified Erbium-doped fiber laser. The periodic beating behavior that occurs during the build-up and disappearance of conventional solitons was discovered in a nonlinear polarization rotation (NPR) fiber lasers. We suggest the reasonable assumption that the periodic beating during the dynamic evolution may be a close connection with the modulation depth of the intracavity saturable absorber The results of this study can deepen researchers' understanding of the evolution of CSs and provide additional judgment dimensions for optimizing the laser parameters.
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