scholarly journals A Color Restoration Algorithm for Diffractive Optical Images of Membrane Camera

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1053
Author(s):  
Yanlei Du ◽  
Xiaofeng Yang ◽  
Yiping Ma ◽  
Chunxue Xu
Keyword(s):  
Computational Efficiency ◽  
Imaging System ◽  
Chromatic Aberration ◽  
Earth Orbit ◽  
Diffractive Imaging ◽  
Optical Images ◽  
Geo Satellite ◽  
Restoration Algorithm ◽  
Color Restoration ◽  
Algorithm Framework

In order to verify the technology of the membrane diffractive imaging system for Chinese next generation geo-stationary earth orbit (GEO) satellite, a series of ground experiments have been carried out using a membrane optical camera with 80 mm aperture (Φ80) lens. The inherent chromatic aberration due to diffractive imaging appears in the obtained data. To address the issue, an effective color restoration algorithm framework by matching, tailoring, and non-linearly stretching the image histograms is proposed in this letter. Experimental results show the proposed approach has good performances in color restoration of the diffractive optical images than previous methods. The effectiveness and robustness of the algorithm are also quantitatively assessed using various color deviation indexes. The results indicate that the chromatic aberration of diffractive images can be effectively removed by about 85%. Also, the proposed method presents reasonable computational efficiency.

New Aspects in the Design of Electron Optical Magnification Systems

1972 ◽  
Vol 30 ◽  
pp. 606-607
Author(s):  
Willem H.J. Andersen
Keyword(s):  
Electron Microscope ◽  
Imaging System ◽  
Chromatic Aberration ◽  
Research Tool ◽  
Energy Losses ◽  
Objective Lens ◽  
Theoretical Limit ◽  
Optical Magnification ◽  
Chromatic Aberrations ◽  
High Degree

Electron microscope design, and particularly the design of the imaging system, has reached a high degree of perfection. Present objective lenses perform up to their theoretical limit, while the whole imaging system, consisting of three or four lenses, provides very wide ranges of magnification and diffraction camera length with virtually no distortion of the image. Evolution of the electron microscope in to a routine research tool in which objects of steadily increasing thickness are investigated, has made it necessary for the designer to pay special attention to the chromatic aberrations of the magnification system (as distinct from the chromatic aberration of the objective lens). These chromatic aberrations cause edge un-sharpness of the image due to electrons which have suffered energy losses in the object.There exist two kinds of chromatic aberration of the magnification system; the chromatic change of magnification, characterized by the coefficient Cm, and the chromatic change of rotation given by Cp.

Electron Holography Improving Transmission Electron Microscopy

1990 ◽  
Vol 48 (1) ◽  
pp. 208-209
Author(s):  
Hannes Lichte
Keyword(s):  
Electron Microscopy ◽  
Transfer Functions ◽  
Imaging System ◽  
Spherical Aberration ◽  
Image Plane ◽  
Chromatic Aberration ◽  
Object Wave ◽  
Objective Lens ◽  
Electron Holography ◽  
Wave Aberration

Generally, the electron object wave o(r) is modulated both in amplitude and phase. In the image plane of an ideal imaging system we would expect to find an image wave b(r) that is modulated in exactly the same way, i. e. b(r) =o(r). If, however, there are aberrations, the image wave instead reads as b(r) =o(r) * FT(WTF) i. e. the convolution of the object wave with the Fourier transform of the wave transfer function WTF . Taking into account chromatic aberration, illumination divergence and the wave aberration of the objective lens, one finds WTF(R) = Echrom(R)Ediv(R).exp(iX(R)) . The envelope functions Echrom(R) and Ediv(R) damp the image wave, whereas the effect of the wave aberration X(R) is to disorder amplitude and phase according to real and imaginary part of exp(iX(R)) , as is schematically sketched in fig. 1.Since in ordinary electron microscopy only the amplitude of the image wave can be recorded by the intensity of the image, the wave aberration has to be chosen such that the object component of interest (phase or amplitude) is directed into the image amplitude. Using an aberration free objective lens, for X=0 one sees the object amplitude, for X= π/2 (“Zernike phase contrast”) the object phase. For a real objective lens, however, the wave aberration is given by X(R) = 2π (.25 Csλ3R4 + 0.5ΔzλR2), Cs meaning the coefficient of spherical aberration and Δz defocusing. Consequently, the transfer functions sin X(R) and cos(X(R)) strongly depend on R such that amplitude and phase of the image wave represent only fragments of the object which, fortunately, supplement each other. However, recording only the amplitude gives rise to the fundamental problems, restricting resolution and interpretability of ordinary electron images:

A Modified Multi Scale Retinex with Color Restoration Algorithm for Automatic Enhancement of Landsat-5 Remote Sensing Image

2011 ◽  
Vol 341-342 ◽  
pp. 893-897
Author(s):  
Gui Zhou Wang ◽  
Guo Jin He
Keyword(s):  
Image Enhancement ◽  
Dynamic Range ◽  
Color Constancy ◽  
Human Perception ◽  
Histogram Equalization ◽  
Image Processing Algorithm ◽  
Multi Scale ◽  
Dynamic Range Compression ◽  
Restoration Algorithm ◽  
Color Restoration

The retinex is a human perception based image processing algorithm which provides color constancy and dynamic range compression. The multi scale retinex with color restoration (MSRCR) has shown itself to be a very versatile automatic image enhancement algorithm that simultaneously provides dynamic range compression, color constancy, and color rendition. But the MSRCR results suffer from lower global brightness and partial color distortion. In order to improve the MSRCR method, this paper presents a modified MSRCR algorithm to Landsat-5 image enhancement considering percent liner stretch and histogram adjustment. Finally, the effect of modified MSRCR method on Landsat-5 image enhancement is analyzed and the comparison with other color adjustment methods such as gamma correction and histogram equalization is reported in the experimental results.

IR performance study of an adaptive coded aperture "diffractive imaging" system employing MEMS "eyelid shutter" technologies

2007 ◽  
Author(s):  
A. Mahalanobis ◽  
C. Reyner ◽  
H. Patel ◽  
T. Haberfelde ◽  
David Brady ◽  
...  
Keyword(s):  
Imaging System ◽  
Coded Aperture ◽  
Performance Study ◽  
Diffractive Imaging

Ocean Zooglider:  an autonomous vehicle for optical and acoustic sensing of zooplankton and suspended particles

2021 ◽  
Author(s):  
Sven Gastauer ◽  
Jeffrey S. Ellen ◽  
Mark D. Ohman
Keyword(s):  
Autonomous Navigation ◽  
Adaptive Sampling ◽  
Marine Mammals ◽  
Imaging System ◽  
Autonomous Vehicle ◽  
Three Dimensional ◽  
Marine Snow ◽  
Seafloor Topography ◽  
Optical Images ◽  
Mission Duration

<p><em>Zooglider</em> is an autonomous buoyancy-driven ocean glider designed and built by the Instrument Development Group at Scripps. <em>Zooglider</em> includes a low power camera with a telecentric lens for shadowgraph imaging and two custom active acoustics echosounders (operated at 200/1000 kHz).  A passive acoustic hydrophone records vocalizations from marine mammals, fishes, and ambient noise.  The imaging system (<em>Zoocam</em>) quantifies zooplankton and ‘marine snow’ as they flow through a sampling tunnel within a well-defined sampling volume. Other sensors include a pumped Conductivity-Temperature-Depth probe and Chl-<em>a</em> fluorometer.  An acoustic altimeter permits autonomous navigation across regions of abrupt seafloor topography, including submarine canyons and seamounts.  Vertical sampling resolution is typically 5 cm, maximum operating depth is ~500 m, and mission duration up to 50 days.  Adaptive sampling is enabled by telemetry of measurements at each surfacing.  Our post-deployment processing methodology classifies the optical images using advanced Deep Learning methods that utilize context metadata.  <em>Zooglider</em> permits in situ measurements of mesozooplankton and marine snow - and their natural, three dimensional orientation - in relation to other biotic and physical properties of the ocean water column.  <em>Zooglider</em> resolves micro-scale patches, which are important for predator-prey interactions and biogeochemical cycling. </p><p> </p>

Modeling and design of a multichannel chromatic aberration compensated imaging system

2015 ◽  
Author(s):  
Gebirie Y. Belay ◽  
Heidi Ottevaere ◽  
Michael Vervaeke ◽  
Jürgen Van Erps ◽  
Hugo Thienpont
Keyword(s):  
Imaging System ◽  
Chromatic Aberration

Neutron Image Restoration by Combining Richardson-Lucy With Steering Kernel

2013 ◽  
Author(s):  
Shuang Qiao ◽  
Qiao Wang ◽  
Jipeng Huang
Keyword(s):  
Imaging System ◽  
Signal To Noise Ratio ◽  
Neutron Imaging ◽  
Low Contrast ◽  
Image Characteristics ◽  
Restoration Algorithm ◽  
Degraded Image ◽  
Neutron Image ◽  
Noise Amplification ◽  
Work Done

Neutron image obtained from a small digital neutron imaging system, always has characteristics of low contrast, blurred edges and serious noise. It is disadvantageous to further analyse information about the sample’s internal structure, so it is essential for the observer to process the degraded image to improve its visual quality. In order to avoid the noise amplification problem of the original Richardson-Lucy (R-L) algorithm, which is adopted to recover degraded image, a restoration algorithm by combining R-L algorithm with Steering Kernel (S-K) algorithm for neutron image is presented in this paper. First S-K algorithm is applied to restrain the noise of the blurred noisy neutron image, as well as improving the signal-to-noise ratio of the image, and then R-L algorithm is used to reconstruct the blurred noisy image. The proposed algorithm is able to make up for the deficiency of R-L algorithm in dealing with the noise amplification problem, which is caused by the repeated iteration, while retaining the details of the image characteristics as much as possible. Comparative experimental results show that the algorithm can obtain satisfactory restoration visual effect for neutron image. The details of the work done are described in this paper.

scholarly journals Global clear-sky surface skin temperature from multiple satellites using a single-channel algorithm with viewing zenith angle correction

2016 ◽  
Author(s):  
Benjamin R. Scarino ◽  
Patrick Minnis ◽  
Thad Chee ◽  
Kristopher M. Bedka ◽  
Christopher R. Yost ◽  
...  
Keyword(s):  
Skin Temperature ◽  
Real Time ◽  
Single Channel ◽  
Weather Prediction ◽  
Surface Radiation ◽  
Earth Orbit ◽  
Viewing Angle ◽  
Clear Sky ◽  
Geo Satellite ◽  
Surface Skin Temperature

Abstract. Surface skin temperature (Ts) is an important parameter for characterizing the energy exchange at the ground/water-atmosphere interface. The Satellite ClOud and Radiation Property retrieval System (SatCORPS) employs a single-channel thermal-infrared- (TIR-) method to retrieve Ts over clear-sky land and ocean surfaces from data taken by geostationary-Earth orbit (GEO) satellite and low-Earth orbit (LEO) satellite imagers. GEO satellites can provide somewhat continuous estimates of Ts over the diurnal cycle in non-polar regions, while polar Ts retrievals from LEO imagers, such as the Advanced Very High Resolution Radiometer (AVHRR) can complement the GEO measurements. The combined global coverage of remotely sensed Ts, along with accompanying cloud and surface radiation parameters, produced in near-real time and from historical satellite data, should be beneficial for both weather and climate applications. For example, near-real-time hourly Ts observations can be assimilated in high-temporal resolution numerical weather prediction models and historical observations can be used for validation or assimilation of climate models. Key drawbacks to the utility of TIR-derived Ts, data include the limitation to clear-sky conditions, the reliance on a particular set of analyses/reanalyses necessary for atmospheric corrections, and the dependence on viewing angle. Therefore, Ts validation with established references is essential, as is proper evaluation of Ts sensitivity to atmospheric correction source. This article presents improvements on the NASA Langley GEO satellite and AVHRR TIR-based Ts product, derived using a single-channel technique. The resulting clear-sky skin temperature values are validated with surface references and independent satellite products. Furthermore, an empirical means of correcting for the viewing-angle dependency of satellite land surface temperature (LST) is explained and validated. Application of a daytime nadir-normalization model yields improved accuracy and precision of GOES-13 LST relative to independent Moderate-resolution Imaging Spectroradiometer (MYD11_L2) LST and Atmospheric Radiation Measurement Program/NOAA ESRL Surface Radiation network ground stations. These corrections serve as a basis for a means to improve satellite-based LST accuracy, thereby leading to better monitoring and utilization of the data. The immediate availability and broad coverage of these skin temperature observations should prove valuable to modelers and climate researchers looking for improved forecasts and better understanding of the global climate model.

scholarly journals Spatial characteristics of wave-like structures in diffuse aurora obtained using optical observations

2012 ◽  
Vol 30 (12) ◽  
pp. 1693-1701 ◽  
Author(s):  
K. Axelsson ◽  
T. Sergienko ◽  
H. Nilsson ◽  
U. Brändström ◽  
Y. Ebihara ◽  
...  
Keyword(s):  
Imaging System ◽  
Particle Interaction ◽  
High Energy ◽  
Temporal Variations ◽  
Optical Observations ◽  
Plasma Convection ◽  
Loss Cone ◽  
Optical Images ◽  
Whistler Mode Waves ◽  
Diffuse Aurora

Abstract. We present the results of a statistical study using optical images from ALIS (Auroral Large Imaging System) to investigate the spatial and temporal variations of structures in diffuse aurora. Analysis of conjugate Reimei data shows that such fine structures are a result of modulation of high-energy precipitating electrons. Pitch angle diffusion into the loss cone due to interaction of whistler mode waves with plasma sheet electrons is the most feasible mechanism leading to high-energy electron precipitation. This suggests that the fine structure is an indication of modulations of the efficiency of the wave–particle interaction. The scale sizes and variations of these structures, mapped to the magnetosphere, can give us information about the characteristics of the modulating wave activity. We found the scale size of the auroral stripes and the spacing between them to be on average 13–14 km, which corresponds to 3–4 ion gyro radii for protons with an energy of 7 keV. The structures move southward with a speed close to zero in the plasma convection frame.

Sign in / Sign up

Export Citation Format

Share Document