This paper makes an investigation of the dehazing effects on image and video coding for surveillance systems. The goal is to achieve good dehazed images and videos at the receiver while sustaining low bitrates (using compression) in the transmission pipeline. At first, this paper proposes a novel method for single-image dehazing, which is used for the investigation. It operates at a faster speed than current methods and can avoid halo effects by using the median operation. We then consider the dehazing effects in compression by investigating the coding artifacts and motion estimation in cases of applying any dehazing method before or after compression. We conclude that better dehazing performance with fewer artifacts and better coding efficiency is achieved when the dehazing is applied before compression. Simulations for Joint Photographers Expert Group images in addition to subjective and objective tests with H.264 compressed sequences validate our conclusion.
The
sodium ion battery (NIB) is a promising alternative technology
for energy storage systems because of the abundance and low cost of
sodium in the Earth’s crust. However, the limited cycle life
and safety concerns of NIBs hinder their large-scale applications.
Here, we report a nonflammable localized high concentration electrolyte
(sodium bis(fluorosulfonyl)imide-triethyl phosphate/1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl
ether (1:1.5:2 in molar ratio)) for highly reversible NIBs. By using
a cryo-transmission electron microscope, it was found that an ultrathin
(3 nm) and robust interphase layer formed on the cathode surface can
block transition metal dissolutions and minimize surface reconstructions
of the cathode. The inorganic-rich solid electrolyte interphase formed
on the hard carbon (HC) surface minimized undesirable reactions between
HC and the electrolyte. These stable interphases enabled high Coulombic
efficiency and long-term stable cycling of the HC anode and the NaCu1/9Ni2/9Fe1/3Mn1/3O2 cathode. The insights obtained in this work can be used to further
improve the cycling stability and safety of rechargeable batteries.
A fuzzy filter adaptive to both sample's activity and the relative position between samples is proposed to reduce the artifacts in compressed multidimensional signals. For JPEG images, the fuzzy spatial filter is based on the directional characteristics of ringing artifacts along the strong edges. For compressed video sequences, the motion compensated spatiotemporal filter (MCSTF) is applied to intraframe and interframe pixels to deal with both spatial and temporal artifacts. A new metric which considers the tracking characteristic of human eyes is proposed to evaluate the flickering artifacts. Simulations on compressed images and videos show improvement in artifact reduction of the proposed adaptive fuzzy filter over other conventional spatial or temporal filtering approaches.
We propose a fast subpixel motion estimation method for motion deblurring, where conventional motion estimation algorithms used in video codings are too complex. The new algorithm is a combination of block matching and optical flow. It does not require any interpolation and it does not provide motion compensated frames. Thus it is much faster than conventional methods. Statistical results show that the new algorithm performs quickly and accurately. It also demonstrates compatible performance with the benchmarking full search algorithm, yet uses significantly less amount of time.
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