The images that are captured in sand storms often suffer from low contrast and serious color cast that are caused by sand dust, and these issues will have significant negative effects on the performance of an outdoor computer vision system. To address these problems, a method based on halo-reduced dark channel prior (DCP) dehazing for sand dust image enhancement is proposed in this paper. It includes three components in sequence: color correction in the LAB color space based on gray world theory, dust removal using a halo-reduced DCP dehazing method, and contrast stretching in the LAB color space using a Gamma function improved contrast limited adaptive histogram equalization (CLAHE), in which a guided filter is used to improve the artifacts of the histogram equalization. Experiments on a large number of real sand dust images demonstrate that the proposed method can well remove the overall yellowing tone and dust haze effect and obtain normal visual colors and a detailed clear image.
INDEX TERMSNormalized Gamma correction (NGC), DCP, CLAHE, color correction, LAB color space, illumination enhancement. ZHENGHAO SHI received the B.S. degree in material science and engineering from Dalian Jiaotong University, Dalian, China, in 1995, the M.S. degree in computer application technology from the
Phosphorene exhibits great potential applications in nanoelectronics due to its relatively large and direct band gap and good charge carrier mobility, and thus has attracted extensive attentions over the past few years. In this study, a novel hybrid phosphorene with a tricycle-like bulge is proposed using density functional theory calculations. Herein, structural stability, elastic, electronic, and optical properties have been addressed. It is found that all the hybrid phosphorenes are stable, and their cohesive energies are very close to that of black phosphorene monolayer. Due to the tricycle-like bulge, these hybrid layers are much softer than the black phosphorene. Their electronic band structures show that they are semiconductors with a robust indirect band gap, and their band gaps are strongly dependent on the sizes. Spatial charge distribution to the valence band maximum and the conduction band minimum is analyzed to explore the origin of the indirect band gap features. By calculating the complex dielectric function, optical properties have been discussed. Our results suggest that the hybrid phosphorenes with well structural stability, robust indirect band gaps, flexible property, and good optical absorption hold great promise for applications in the field of visible light harvesting and flexible nanoelectronic devices.
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