Low-Complexity Power-Balancing-Point Based Optimization for Photovoltaic Differential Power Processing
DOI:10.1109/TPEL.2020.2977329
期刊:IEEE Transactions on Power Electronics
出版年份:2020
更新时间:2025-09-19 17:13:59
摘要:
With the steadily increasing spatial resolution of synthetic aperture radar images, the need for a consistent but locally adaptive image enhancement rises considerably. Numerous studies already showed that adaptive multilooking, able to adjust the degree of smoothing locally to the size of the targets, is superior to uniform multilooking. This study introduces a novel approach of multiscale and multidirectional multilooking based on intensity images exclusively but applicable to an arbitrary number of image layers. A set of 2-D circular and elliptical ?lter kernels in different scales and orientations (named Schmittlets) is derived from hyperbolic functions. The original intensity image is transformed into the Schmittlet coef?cient domain where each coef?cient measures the existence of Schmittlet-like structures in the image. By estimating their signi?cance via the perturbation-based noise model, the best-?tting Schmittlets are selected for image reconstruction. On the one hand, the index image indicating the locally best-?tting Schmittlets is utilized to consistently enhance further image layers, e.g., multipolarized, multitemporal, or multifrequency layers, and on the other hand, it provides an optimal description of spatial patterns valuable for further image analysis. The ?nal validation proves the advantages of the Schmittlets over six contemporary speckle reduction techniques in six different categories (preservation of the mean intensity, equivalent number of looks, and preservation of edges and local curvature both in strength and in direction) by the help of four test sites on three resolution levels. The additional value of the Schmittlet index layer for automated image interpretation, although obvious, still is subject to further studies.