Showing papers by "Hang Zhao published in 2014"
06 Sep 2014
TL;DR: It is shown that recording multiple images, transformed in the octic group, with a sensor of asymmetric sub-pixel layout increases the spatial sampling compared to a conventional sensor with a rectilinear grid of pixels and hence increases the image resolution.
Abstract: This paper presents a novel super-resolution framework by exploring the properties of non-conventional pixel layouts and shapes. We show that recording multiple images, transformed in the octic group, with a sensor of asymmetric sub-pixel layout increases the spatial sampling compared to a conventional sensor with a rectilinear grid of pixels and hence increases the image resolution. We further prove a theoretical bound for achieving well-posed super-resolution with a designated magnification factor w.r.t. the number and distribution of sub-pixels. We also propose strategies for selecting good sub-pixel layouts and effective super-resolution algorithms for our setup. The experimental results validate the proposed theory and solution, which have the potential to guide the future CCD layout design with super-resolution functionality.
13 citations
TL;DR: An advanced computational imaging system with an optical architecture that enables simultaneous and dynamic pupil-plane and image-plane coding accommodating several task-specific applications is described.
Abstract: United States. Dept. of Defense. Assistant Secretary of Defense for Research & Engineering (Air Force contract #FA8721-05-C-002)
13 citations
23 Oct 2014
TL;DR: The results show that combinations of vertical-vertical and slant 45° - vertical polarization pair have relative low penetration losses and high reflectivity, meaning that the signal would be contained within a room or within the hallway in such environment with an in-building base station.
Abstract: In this paper, we present measurement results of material penetration loss and reflection coefficient as a function of antenna polarization at 5.8 GHz. The measurements were made in a typical building hallway with a variety of test materials. This is a unique measurement campaign because the same antenna apertures were used to create three different types of polarizations: linear, circular polarized, and slant 45°. With the given antenna pair, each having a gain of 6 dBi, and a vector network analyzer; we developed measurements of penetration and reflection for dry wall, wood, door window, and steel door, along with five different combinations of antenna polarizations. For each of the above mentioned materials, we have measured the penetration loss and reflection coefficients for all five polarizations and then compared them. The results show that combinations of vertical-vertical and slant 45° — slant 45° polarizations have relative low penetration losses and high reflectivity, meaning that the signal would be contained within a room or within the hallway in such environment with an in-building base station. Also, it was concluded that co-circular polarized waves would become cross circular polarized when received after a single reflection. Lastly, a generalized comparison is made between the measurement using a slant 45° — vertical polarization pair to the other combinations of antenna polarization.
2 citations