Light scattering and color change are two main problems in underwater images. Due to light scattering, incident light gets reflected and deflected multiple times by particles present in the water. This degrades the visibility and contrast of the underwater image. Dark channel prior is method used for removing the haze present in the underwater image. It is based on a key observation -most local patches in haze-free underwater images contain some pixels which have very low intensities in at least one color channel. Using this prior with the haze imaging color model estimates the thickness of the haze and recover a high quality hazefree image. This method does not require images with different exposure values, and is entirely based on the attenuation experienced by point across multiple frames. In this paper underwater image enhancement using Dark channel Prior is attempted. Results shows that the performance of this method is better compared to image enhancement using histogram equalization
Keywords-Local patches, Dark channel prior, MATLAB/SimulinkI.
This paper presents the design and simulation of Silicon Carbide (SiC) based technology, Indium Gallium Nitride (InGaN) Multiple Quantum Well (MQW) Light-Emitting Diode (LED) with a Compositionally Step Graded (CSG) InGaN barrier and V-Shaped well in the active region. The simulations are obtained in Silvaco Computer Aided Design simulator and parameters such as Internal Quantum Efficiency (IQE) with respect to input current, spontaneous emission in regard to wavelength and power versus current in the device are theoretically studied. The CSG InGaN barrier LED with V-shaped quantum well shows substantial growth in output power when compared to the CSG GaN barrier structure with conventional MQW. The high carrier confinement in the V-shape well causes, transportation/injection of hole and change in band bending due to polarization effect. Moreover, lattice-matched SiC substrate over GaN material increases the InGaN V-shaped MQW LEDs radiative recombination rate which in turn leads to high output power. The optical luminous power of 160mW and 82% of peak IQE, emitting wavelength at 460 nm and 200mA of injection current is obtained for the proposed LED. The enactment of the V shape MQW CSG-InGaN device technology is a good alternative choice for commercial and industrial lighting applications.
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