A Spatial-Enhanced LSE-SFIM Algorithm for Hyperspectral and Multispectral Images Fusion

The fusion of a hyperspectral image (HSI) and multispectral image (MSI) can significantly improve the ability of ground target recognition and identification. The quality of spatial information and the fidelity of spectral information are normally contradictory. However, these two properties are non-negligible indicators for multi-source remote-sensing images fusion. The smoothing filter-based intensity modulation (SFIM) method is a simple yet effective model for image fusion, which can improve the spatial texture details of the image well, and maintain the spectral characteristics of the image significantly. However, traditional SFIM has a poor effect for edge information sharpening, leading to a bad overall fusion result. In order to obtain better spatial information, a spatial filter-based improved LSE-SFIM algorithm is proposed in this paper. Firstly, the least square estimation (LSE) algorithm is combined with SFIM, which can effectively improve the spatial information quality of the fused image. At the same time, in order to better maintain the spatial information, four spatial filters (mean, median, nearest and bilinear) are used for the simulated MSI image to extract fine spatial information. Six quality indexes are used to compare the performance of different algorithms, and the experimental results demonstrate that the LSE-SFIM based on bilinear (LES-SFIM-B) performs significantly better than the traditional SFIM algorithm and other spatially enhanced LSE-SFIM algorithms proposed in this paper. Furthermore, LSE-SFIM-B could also obtain similar performance compared with three state-of-the-art HSI-MSI fusion algorithms (CNMF, HySure, and FUSE), while the computing time is much shorter.

The HASHTAG Project: The First Submillimeter Images of the Andromeda Galaxy from the Ground

Observing nearby galaxies with submillimeter telescopes on the ground has two major challenges. First, the brightness is significantly reduced at long submillimeter wavelengths compared to the brightness at the peak of the dust emission. Second, it is necessary to use a high-pass spatial filter to remove atmospheric noise on large angular scales, which has the unwelcome side effect of also removing the galaxy’s large-scale structure. We have developed a technique for producing high-resolution submillimeter images of galaxies of large angular size by using the telescope on the ground to determine the small-scale structure (the large Fourier components) and a space telescope (Herschel or Planck) to determine the large-scale structure (the small Fourier components). Using this technique, we are carrying out the HARP and SCUBA-2 High Resolution Terahertz Andromeda Galaxy Survey (HASHTAG), an international Large Program on the James Clerk Maxwell Telescope, with one aim being to produce the first high-fidelity high-resolution submillimeter images of Andromeda. In this paper, we describe the survey, the method we have developed for combining the space-based and ground-based data, and we present the first HASHTAG images of Andromeda at 450 and 850 μm. We also have created a method to predict the CO(J = 3–2) line flux across M31, which contaminates the 850 μm band. We find that while normally the contamination is below our sensitivity limit, it can be significant (up to 28%) in a few of the brightest regions of the 10 kpc ring. We therefore also provide images with the predicted line emission removed.

High-NA optical edge detection via optimized multilayer films

There has been a significant effort to design nanophotonic structures that process images at the speed of light. A prototypical example is in edge detection, where photonic-crystal-, metasurface-, and plasmon-based designs have been proposed and in some cases experimentally demonstrated. In this work, we show that multilayer optical interference coatings can achieve visible-frequency edge detection in transmission with high numerical aperture, two-dimensional image formation, and straightforward fabrication techniques, unique among all nanophotonic approaches. We show that the conventional Laplacian-based transmission spectrum may not be ideal once the scattering physics of real designs is considered, and show that better performance can be attained with alternative spatial filter functions. Our designs, comprising alternating layers of Si and SiO2 with total thicknesses of only 1 µm, demonstrate the possibility for optimized multilayer films to achieve state-of-the-art edge detection, and, more broadly, analog optical implementations of linear operators.

Directional Moiré Boosting Using Spatial Filtering

Overlapping of two or more grating structures of small frequency differences gives rise to the Moiré patterns. While the overall moiré patterns are widely studied, in many cases – specially in case of a zonal fringe analysis – zone or direction based highlighting or suppression of moiré patterns are very helpful. This paper presents a simple method for directional boosting of moiré patterns, generated using Spatial Light Modulator (SLM) based interferometric setup, using the spatial filtering technique. Keywords: Moiré, Spatial Filter, Directional Boosting, Interferometry, Spatial Light Modulator, Optics

Method for encryption of cartographic images on the basis of internal reorganization of the digital filter structure

The paper presents a method for encrypting geo-images based on the reorganization of the internal structure of the filter. Methods for digital image filtering in the MATLAB environment are taken as a basis. The essence of encryption is to control the aliasing of noise and the kernel of smearing. Knowing these values will allow the addressee to recover the transmitted cards with minimal interference, which will be unattainable for the data interceptor. Under conditions of unfavorable factors, conditions sometimes arise that lead to the loss of information content of images and, as a consequence, damage to information. Therefore, the development of methods to minimize their influence is an urgent task of the study. Thus, one of the approaches to the construction of spatial filters with a controlled structure is proposed for the selection of contrasting images in noises of different intensities. The procedure for converting any spatial filter from an initial display to a form that allows you to control its internal state is described. The obtained results of the original and transformed images make it possible to draw conclusions about the possibility of practical application of the proposed invariant spatial filter in the blocks for analyzing the original image. The method can be used to transfer photo, video messages and text information between consumers using data transmission systems for any purpose. Due to the factorial dependence, it is very problematic for information interceptors to find the required resulting position of all image encryption parameters (sizes, type of the distortion function, regularization parameters α and σ) for information interceptors, since the computational costs are not commensurate with the capabilities of modern computers. This can be used to transfer photo, video messages and text information between consumers using data transmission systems for any purpose, especially when transferring cartographic information.

Spatial and Temporal Characteristic Analysis of Imbalance Usage in the Hangzhou Public Bicycle System

Calculating the availability of bicycles and racks is a traditional method for detecting imbalance usage in a public bicycle system (PBS). However, for bike-sharing systems in Asian countries, which have compact layouts and larger system scales, an alternative docking station may be found within walking distance. In this paper, we proposed a synthetic and spatial-explicit approach to discover the imbalance usage by using the Hangzhou public bicycle system as an example. A spatial filter was used to remove the false-alarm docking stations and to obtain true imbalance areas of interest (AOI), where the system operation department installs more stations or increases the capacity of existing stations. In addition, sub-nearest neighbor analysis was adopted to determine the average distance between stations, resulting in an average station spacing of 190 m rather than 15.5 m, which can reflect the nonbiased service level of Hangzhou’s public bicycle systems. Our study shows that neighboring stations are taken into account when analyzing PBSs that use a staggered or face-to-face layout, and our method can reduce the number of problematic stations that need to be reallocated by about 92.81%.