Journal articles: 'Snapshot images'

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Bond, Howard E., Laura K. Fullton, Karen G. Schaefer, Robin Ciardullo, and Michael Sipior. "HST Snapshot images of Planetary Nebulae." Symposium - International Astronomical Union 180 (1997): 211–12. http://dx.doi.org/10.1017/s0074180900130347.

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During Cycle 5 of the HST General Observer program we have been carrying out a “snapshot” survey of central stars of planetary nebulae. The snapshots are short exposures in the V (F555W) and I (F814W) filters, taken with the Wide Field Planetary Camera (WFPC2) during brief scheduling opportunities.

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McClung, Andrew, Sarath Samudrala, Mahsa Torfeh, Mahdad Mansouree, and Amir Arbabi. "Snapshot spectral imaging with parallel metasystems." Science Advances 6, no. 38 (September 2020): eabc7646. http://dx.doi.org/10.1126/sciadv.abc7646.

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Spectral imagers divide scenes into quantitative and narrowband spectral channels. They have become important metrological tools in many areas of science, especially remote sensing. Here, we propose and experimentally demonstrate a snapshot spectral imager using a parallel optical processing paradigm based on arrays of metasystems. Our multi-aperture spectral imager weighs less than 20 mg and simultaneously acquires 20 image channels across the 795- to 980-nm spectral region. Each channel is formed by a metasurface-tuned filter and a metalens doublet. The doublets incorporate absorptive field stops, reducing cross-talk between image channels. We demonstrate our instrument’s capabilities with both still images and video. Narrowband filtering, necessary for the device’s operation, also mitigates chromatic aberration, a common problem in metasurface imagers. Similar instruments operating at visible wavelengths hold promise as compact, aberration-free color cameras. Parallel optical processing using metasystem arrays enables novel, compact instruments for scientific studies and consumer electronics.

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Simarro, Gonzalo, Daniel Calvete, Paola Souto, and Jorge Guillén. "Camera Calibration for Coastal Monitoring Using Available Snapshot Images." Remote Sensing 12, no. 11 (June 6, 2020): 1840. http://dx.doi.org/10.3390/rs12111840.

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Joint intrinsic and extrinsic calibration from a single snapshot is a common requirement in coastal monitoring practice. This work analyzes the influence of different aspects, such as the distribution of Ground Control Points (GCPs) or the image obliquity, on the quality of the calibration for two different mathematical models (one being a simplification of the other). The performance of the two models is assessed using extensive laboratory data (i.e., snapshots of a grid). While both models are able to properly adjust the GCPs, the simpler model gives a better overall performance when the GCPs are not well distributed over the image. Furthermore, the simpler model allows for better recovery of the camera position and orientation.

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Langford, Martha. "Snapshot Photography: The Lives of Images." History of Photography 38, no. 4 (October 2, 2014): 443–45. http://dx.doi.org/10.1080/03087298.2014.949108.

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Burgess, A. M., and R. W. Hunstead. "Snapshot Imaging with the Australia Telescope Compact Array." Publications of the Astronomical Society of Australia 12, no. 2 (August 1995): 227–38. http://dx.doi.org/10.1017/s1323358000020312.

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AbstractRadio snapshot imaging is an efficient observing method which allows several sources to be observed in the one session. Snapshot observing with the Australia Telescope Compact Array (ATCA) involves special difficulties, as the small number of antennas combined with the short total integration time leads to high sidelobe levels in the raw images. The images can be improved markedly by standard deconvolution techniques, but more care is required in their use because of the difficulty in distinguishing real emission from artefacts. This study, based on a set of snapshot observations of strong sources at 5 GHz, gives guidance on both the planning of observations and the data reduction. We show that snapshot imaging with the 6 km ATCA can achieve a dynamic range of 100–200:1 provided certain conditions are met, namely a peak flux density > 100 mJy, an angular size ≤ 30″ and an hour-angle coverage spanning at least six well-separated 5-minute cuts. When observing weak sources it is essential for calibration sources to be selected carefully and observed frequently.

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Evans, Sarah. "Snapshot Photography: The Lives of Images by Catherine Zuromskis." Biography 38, no. 3 (2015): 436–37. http://dx.doi.org/10.1353/bio.2015.0028.

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Chalfen, Richard. "Snapshot photography: the lives of images by Catherine Zuromskis." Visual Studies 31, no. 2 (March 20, 2015): 157–58. http://dx.doi.org/10.1080/1472586x.2015.1020085.

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Wang, Pu, Gianluca Turcatel, Cosimo Arnesano, David Warburton, Scott E. Fraser, and Francesco Cutrale. "Fiber pattern removal and image reconstruction method for snapshot mosaic hyperspectral endoscopic images." Biomedical Optics Express 9, no. 2 (January 25, 2018): 780. http://dx.doi.org/10.1364/boe.9.000780.

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Jura, M. "Recent and Future Studies of Circumstellar Matter – A Snapshot." Symposium - International Astronomical Union 191 (1999): 603–10. http://dx.doi.org/10.1017/s0074180900203604.

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At this meeting, powerful new images and spectroscopy of AGB stars were presented. Theoretical models have advanced, and we are learning more from studies of the pre-solar grains isolated from meteorites.We suggest that several mass loss mechanisms may be operating in AGB stars: current images imply both spherical winds and highly flattened outflows. There are good arguments that in some cases, a companion may be critical in driving the final outflow. In the near future, a number of extremely powerful new instruments and techniques will be available that will lead to a much deeper understanding of these systems.

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Gryspeerdt, Edward, Tom Goren, and Tristan W. P. Smith. "Observing the timescales of aerosol–cloud interactions in snapshot satellite images." Atmospheric Chemistry and Physics 21, no. 8 (April 26, 2021): 6093–109. http://dx.doi.org/10.5194/acp-21-6093-2021.

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Abstract. The response of cloud processes to an aerosol perturbation is one of the largest uncertainties in the anthropogenic forcing of the climate. It occurs at a variety of timescales, from the near-instantaneous Twomey effect to the longer timescales required for cloud adjustments. Understanding the temporal evolution of cloud properties following an aerosol perturbation is necessary to interpret the results of so-called “natural experiments” from a known aerosol source such as a ship or industrial site. This work uses reanalysis wind fields and ship emission information matched to observations of ship tracks to measure the timescales of cloud responses to aerosol in instantaneous (or“snapshot”) images taken by polar-orbiting satellites. As in previous studies, the local meteorological environment is shown to have a strong impact on the occurrence and properties of ship tracks, but there is a strong time dependence in their properties. The largest droplet number concentration (Nd) responses are found within 3 h of emission, while cloud adjustments continue to evolve over periods of 10 h or more. Cloud fraction is increased within the early life of ship tracks, with the formation of ship tracks in otherwise clear skies indicating that around 5 %–10 % of clear-sky cases in this region may be aerosol-limited. The liquid water path (LWP) enhancement and the Nd–LWP sensitivity are also time dependent and strong functions of the background cloud and meteorological state. The near-instant response of the LWP within ship tracks may be evidence of a bias in estimates of the LWP response to aerosol derived from natural experiments. These results highlight the importance of temporal development and the background cloud field for quantifying the aerosol impact on clouds, even in situations where the aerosol perturbation is clear.

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Lins, Alene, Madalena Oliveira, and Luís António Santos. "Figurations of the body in the snapshot of digital photojournalism: the non-pose and disfiguration." Comunicação e Sociedade 32 (December 29, 2017): 419–38. http://dx.doi.org/10.17231/comsoc.32(2017).2770.

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This article analyses the technological changes that have modified the snapshot in photojournalism. Formerly, snapshot was a result of the technique and expertise of the photographer. Today, due to a kind of “agility” of the cameras, it has become a possible practice for any photo-reporter. Sequential photographs turn the portrayed subject’s body into a pliant element of the editorial process. In figurations that privilege unfulfilled gestures and disfigurements, some images published by the press symbolically alter the social representation of the person portrayed. The study described within this paper also points to the use of an aesthetic of the grotesque, present in the expressions, gestures and posture of the subject photographed and to a discourse of the snapshot as a regime of power exerted by the press.

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Palmer, Meredith S., Sarah E. Huebner, Marco Willi, Lucy Fortson, and Craig Packer. "Citizen science, computing, and conservation: How can “Crowd AI” change the way we tackle large-scale ecological challenges?" Human Computation 8, no. 2 (July 27, 2021): 54–75. http://dx.doi.org/10.15346/hc.v8i2.123.

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Camera traps - remote cameras that capture images of passing wildlife - have become a ubiquitous tool in ecology and conservation. Systematic camera trap surveys generate ‘Big Data’ across broad spatial and temporal scales, providing valuable information on environmental and anthropogenic factors affecting vulnerable wildlife populations. However, the sheer number of images amassed can quickly outpace researchers’ ability to manually extract data from these images (e.g., species identities, counts, and behaviors) in timeframes useful for making scientifically-guided conservation and management decisions. Here, we present ‘Snapshot Safari’ as a case study for merging citizen science and machine learning to rapidly generate highly accurate ecological Big Data from camera trap surveys. Snapshot Safari is a collaborative cross-continental research and conservation effort with 1500+ cameras deployed at over 40 eastern and southern Africa protected areas, generating millions of images per year. As one of the first and largest-scale camera trapping initiatives, Snapshot Safari spearheaded innovative developments in citizen science and machine learning. We highlight the advances made and discuss the issues that arose using each of these methods to annotate camera trap data. We end by describing how we combined human and machine classification methods (‘Crowd AI’) to create an efficient integrated data pipeline. Ultimately, by using a feedback loop in which humans validate machine learning predictions and machine learning algorithms are iteratively retrained on new human classifications, we can capitalize on the strengths of both methods of classification while mitigating the weaknesses. Using Crowd AI to quickly and accurately ‘unlock’ ecological Big Data for use in science and conservation is revolutionizing the way we take on critical environmental issues in the Anthropocene era.

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Kabsch, Wolfgang. "Processing of X-ray snapshots from crystals in random orientations." Acta Crystallographica Section D Biological Crystallography 70, no. 8 (July 25, 2014): 2204–16. http://dx.doi.org/10.1107/s1399004714013534.

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A functional expression is introduced that relates scattered X-ray intensities from a still or a rotation snapshot to the corresponding structure-factor amplitudes. The new approach was implemented in the programnXDSfor processing monochromatic diffraction images recorded by a multi-segment detector where each exposure could come from a different crystal. For images containing indexable spots, the intensities of the expected reflections and their variances are obtained by profile fitting after mapping the contributing pixel contents to the Ewald sphere. The varying intensity decline owing to the angular distance of the reflection from the surface of the Ewald sphere is estimated using a Gaussian rocking curve. This decline is dubbed `Ewald offset correction', which is well defined even for still images. Together with an image-scaling factor and other corrections, an explicit expression is defined that predicts each recorded intensity from its corresponding structure-factor amplitude. All diffraction parameters, scaling and correction factors are improved by post-refinement. The ambiguous case of a lower point group than the lattice symmetry is resolved by a method reminiscent of the technique of `selective breeding'. It selects the indexing alternative for each image that yields, on average, the highest correlation with intensities from all other images. Processing a test set of rotation images byXDSand treating the same images bynXDSas snapshots of crystals in random orientations yields data of comparable quality, clearly indicating an anomalous signal from Se atoms.

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Spigulis, Janis, Zigmars Rupenheits, Uldis Rubins, Madars Mileiko, and Ilze Oshina. "Spectral Line Reflectance and Fluorescence Imaging Device for Skin Diagnostics." Applied Sciences 10, no. 21 (October 24, 2020): 7472. http://dx.doi.org/10.3390/app10217472.

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The multi-spectral-line imaging concept, which was recently implemented for the snapshot mapping of three main skin chromophores—melanin, oxy-hemoglobin, and deoxy-hemoglobin, is further explored for the snapshot capturing of four spectral line images at wavelengths of 450, 523, 638, and 850 nm, with the consecutive acquiring of a 405 nm excited fluorescence image. A corresponding laser-based prototype device was designed and assembled. Processing of the mentioned five images enables obtaining distribution maps of four skin chromophores within the malformation and comparing their mean fluorescence intensity with that of the surrounding healthy skin. This set of information is helpful for dermatologists, cosmetologists, oncologists, and other healthcare professionals to quantify the diagnosis of skin malformations (including cancers) and to follow up the recovery process after therapy. This paper describes the design of the developed proof-of-concept prototype device and initial test results.

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Smith, Shawn Michelle. "Archive of the Ordinary: Jason Lazarus, Too Hard to Keep." Journal of Visual Culture 17, no. 2 (August 2018): 198–206. http://dx.doi.org/10.1177/1470412918782363.

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This article considers snapshot photography and affect through a reading of artist Jason Lazarus’s Too Hard to Keep. Lazarus’s project is an archive and shifting installation of anonymous photographs that donors can no longer bear to keep. It highlights the dual nature of the photographic snapshot – simultaneously banal and emotionally charged, tedious and intensely affecting, private and public, a site of cultural normativity as well as resistance. The article proposes that because viewers of Lazarus’s installations cannot know what specific feelings any of the images previously evoked, they are encouraged to contemplate shared practices of photography and the diffuse affective charge of ordinary photographs.

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Juntunen, Cory, Isabel M. Woller, and Yongjin Sung. "Hyperspectral Three-Dimensional Fluorescence Imaging Using Snapshot Optical Tomography." Sensors 21, no. 11 (May 24, 2021): 3652. http://dx.doi.org/10.3390/s21113652.

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Hyperspectral three-dimensional (3D) imaging can provide both 3D structural and functional information of a specimen. The imaging throughput is typically very low due to the requirement of scanning mechanisms for different depths and wavelengths. Here we demonstrate hyperspectral 3D imaging using Snapshot projection optical tomography (SPOT) and Fourier-transform spectroscopy (FTS). SPOT allows us to instantaneously acquire the projection images corresponding to different viewing angles, while FTS allows us to perform hyperspectral imaging at high spectral resolution. Using fluorescent beads and sunflower pollens, we demonstrate the imaging performance of the developed system.

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Onishi, Ryo, and Daisuke Sugiyama. "Deep Convolutional Neural Network for Cloud Coverage Estimation from Snapshot Camera Images." SOLA 13 (2017): 235–39. http://dx.doi.org/10.2151/sola.2017-043.

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Trunel, Lucile. "A snapshot of some current digitisation projects in French art libraries." Art Libraries Journal 34, no. 1 (2009): 17–21. http://dx.doi.org/10.1017/s0307472200015716.

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The Gallica programme of the Bibliothèque nationale de France, and the Digital Library of the Institut national d’histoire de l’art (INHA), are two major French initiatives in the digitisation of art history information. Gallica was launched in 1995 and by the end of 2007 incorporated some 80,000 images and 90,000 texts. Essentially encyclopaedic in content, it nevertheless contains much material relevant to art, including iconographic documents from the library’s specialist departments. Mass digitisation of some 100,000 works per annum from 2007 onwards will add a substantial body of texts and periodicals in this subject. INHA’s digitisation programme for its Digital Library began in 2002: the two main areas it is currently concentrating on are a corpus of ‘classics of art history’, and the digitisation of specialised and rare documents such as the pre-1920 catalogues of the Louvre. 200,000 images are already available on line.

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Doran, YJ. "Building knowledge through images in physics." Visual Communication 18, no. 2 (March 8, 2018): 251–77. http://dx.doi.org/10.1177/1470357218759825.

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This article considers the role of images in physics. Utilizing the Systemic Functional Linguistic dimension of field it shows that diagrams that present large classification and composition taxonomies as well as long sequences of activities can be overlaid upon graphs that show arrays of ordered data. Through an analysis using the concepts of semantic density and semantic gravity from Legitimation Code Theory, it is argued that this allows images to present large degrees of meaning in a single snapshot whilst also linking abstracted theory to specific instances of data. That is, the analysis shows that images play a significant role in developing technical physics knowledge through abstractions away from the empirical world. This article contributes to the growing body of research focusing on the structuring of knowledge and the non-linguistic semiotic resources used to organize it.

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Sivkov, S. I., S. P. Simakov, and A. I. Vinokur. "Algorithms for contactless scanning of book monuments." Proceedings of SPSTL SB RAS, no. 3 (September 21, 2021): 9–15. http://dx.doi.org/10.20913/2618-7575-2021-3-9-15.

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The article is devoted to the questions of cultural heritage preservation by creating the digital collection of book monuments. The original documents are monuments of book culture and their dilapidated state requires careful handling, splitting of documents for scanning is extremely undesirable. The market does not present the equipment for contactless scanning of books without embroidering, therefore an algorithm that allows digitalizing book monuments in a contactless way has been developed. The technique has been constructed using an algorithm based on the projection of the light grid on the object scanned. The authors propose a sequence of actions consisting of image processing and comparing the results between two images. The first snapshot determines the initial parameters of the grid; the second snapshot determines the actual distortion of the test snapshot. Subsequent mathematical processing allows getting scanned images without absence of geometric distortions of the scanned page due to the system of using the two-dimensional array of corrections. The application of the system has been modeled on the example of «The legend of the destruction of Siberian cities of Tara and Tyumen by the lesser Tatars / / Collection of moral stories, words, lives and other articles [hand.]». The evaluation parameters of the simulation result have been the following: text distinctness, absence of geometric distortions, color quality, uniformity of document scanning quality within a single book, etc., as checked and recognized as high by the experts.The experience described opens possibilities of book monuments digitization using the new algorithm. The development of the system is aimed at expanding the database of objects of material culture to be digitized, perfecting the software, improving the quality of digital images, as well as the capabilities of image recognition and search for the document itself and information it contains.

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Nguyen, Bao D., and George A. McMechan. "Five ways to avoid storing source wavefield snapshots in 2D elastic prestack reverse time migration." GEOPHYSICS 80, no. 1 (January 1, 2015): S1—S18. http://dx.doi.org/10.1190/geo2014-0014.1.

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Five alternative algorithms were evaluated to circumvent the excessive storage requirement imposed by saving source wavefield snapshots used for the crosscorrelation image condition in 2D prestack elastic reverse time migration. We compared the algorithms on the basis of their ability, either to accurately reconstruct (not save) the source wavefield or to use an alternate image condition so that neither saving nor reconstruction of full wavefields was involved. The comparisons were facilitated by using the same (velocity-stress) extrapolator in all the algorithms, and running them all on the same hardware. We assumed that there was enough memory in a node to do an extrapolation, and that all input data were stored on disk rather than residing in random-access memory. This should provide a fair and balanced comparison. Reconstruction of the source wavefield from boundary and/or initial values reduced the required storage to a very small fraction of that needed to store source wavefield snapshots for conventional crosscorrelation, at the cost of adding an additional source extrapolation. Reverse time checkpointing avoided recursive forward recomputation. Two nonreconstructive imaging conditions do not require full snapshot storage or an additional extrapolation. Time-binning the imaging criteria removed the need for image time searching or sorting. Numerical examples using elastic data from the Marmousi2 model showed that the quality of the elastic prestack PP and PS images produced by the cost-optimized alternative algorithms were (virtually) identical to the higher cost images produced by traditional crosscorrelation.

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Aasen, Helge. "INFLUENCE OF THE VIEWING GEOMETRY WITHIN HYPERSPECTRAL IMAGES RETRIEVED FROM UAV SNAPSHOT CAMERAS." ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences III-7 (June 7, 2016): 257–61. http://dx.doi.org/10.5194/isprsannals-iii-7-257-2016.

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Hyperspectral data has great potential for vegetation parameter retrieval. However, due to angular effects resulting from different sun-surface-sensor geometries, objects might appear differently depending on the position of an object within the field of view of a sensor. Recently, lightweight snapshot cameras have been introduced, which capture hyperspectral information in two spatial and one spectral dimension and can be mounted on unmanned aerial vehicles. This study investigates the influence of the different viewing geometries within an image on the apparent hyperspectral reflection retrieved by these sensors. Additionally, it is evaluated how hyperspectral vegetation indices like the NDVI are effected by the angular effects within a single image and if the viewing geometry influences the apparent heterogeneity with an area of interest. The study is carried out for a barley canopy at booting stage. The results show significant influences of the position of the area of interest within the image. The red region of the spectrum is more influenced by the position than the near infrared. The ability of the NDVI to compensate these effects was limited to the capturing positions close to nadir. The apparent heterogeneity of the area of interest is the highest close to a nadir.

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Aasen, Helge. "INFLUENCE OF THE VIEWING GEOMETRY WITHIN HYPERSPECTRAL IMAGES RETRIEVED FROM UAV SNAPSHOT CAMERAS." ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences III-7 (June 7, 2016): 257–61. http://dx.doi.org/10.5194/isprs-annals-iii-7-257-2016.

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Hyperspectral data has great potential for vegetation parameter retrieval. However, due to angular effects resulting from different sun-surface-sensor geometries, objects might appear differently depending on the position of an object within the field of view of a sensor. Recently, lightweight snapshot cameras have been introduced, which capture hyperspectral information in two spatial and one spectral dimension and can be mounted on unmanned aerial vehicles. This study investigates the influence of the different viewing geometries within an image on the apparent hyperspectral reflection retrieved by these sensors. Additionally, it is evaluated how hyperspectral vegetation indices like the NDVI are effected by the angular effects within a single image and if the viewing geometry influences the apparent heterogeneity with an area of interest. The study is carried out for a barley canopy at booting stage. The results show significant influences of the position of the area of interest within the image. The red region of the spectrum is more influenced by the position than the near infrared. The ability of the NDVI to compensate these effects was limited to the capturing positions close to nadir. The apparent heterogeneity of the area of interest is the highest close to a nadir.

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Tao, Chenning, Huanzheng Zhu, Peng Sun, Rengmao Wu, and Zhenrong Zheng. "Hyperspectral image recovery based on fusion of coded aperture snapshot spectral imaging and RGB images by guided filtering." Optics Communications 458 (March 2020): 124804. http://dx.doi.org/10.1016/j.optcom.2019.124804.

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Chen, Mason T., Faisal Mahmood, Jordan A. Sweer, and Nicholas J. Durr. "GANPOP: Generative Adversarial Network Prediction of Optical Properties From Single Snapshot Wide-Field Images." IEEE Transactions on Medical Imaging 39, no. 6 (June 2020): 1988–99. http://dx.doi.org/10.1109/tmi.2019.2962786.

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Xie, Yunqiang, Chunyu Liu, Shuai Liu, Weiyang Song, and Xinghao Fan. "Snapshot Imaging Spectrometer Based on Pixel-Level Filter Array (PFA)." Sensors 21, no. 7 (March 25, 2021): 2289. http://dx.doi.org/10.3390/s21072289.

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Snapshot spectral imaging technology plays an important role in many fields. However, most existing snapshot imaging spectrometers have the shortcomings of a large volume or heavy computational burden. In this paper, we present a novel snapshot imaging spectrometer based on the pixel-level filter array (PFA), which can simultaneously obtain both spectral and spatial information. The system is composed of a fore-optics, a PFA, a relay lens, and a monochromatic sensor. The incoming light first forms an intermediate image on the PFA through the fore-optics. Then, the relay lens reimages the spectral images on the PFA onto the monochromatic sensor. Through the use of the PFA, we can capture a three-dimensional (spatial coordinates and wavelength) datacube in a single exposure. Compared with existing technologies, our system possesses the advantages of a simple implementation, low cost, compact structure, and high energy efficiency by removing stacked dispersive or interferometric elements. Moreover, the characteristic of the direct imaging mode ensures the low computational burden of the system, thus shortening the imaging time. The principle and design of the system are described in detail. An experimental prototype is built and field experiments are carried out to verify the feasibility of the proposed scheme.

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Blanco-Medina, Pablo, Eduardo Fidalgo, Enrique Alegre, Roberto A. Vasco-Carofilis, Francisco Jañez-Martino, and Victor Fidalgo Villar. "Detecting Vulnerabilities in Critical Infrastructures by Classifying Exposed Industrial Control Systems Using Deep Learning." Applied Sciences 11, no. 1 (January 1, 2021): 367. http://dx.doi.org/10.3390/app11010367.

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Industrial control systems depend heavily on security and monitoring protocols. Several tools are available for this purpose, which scout vulnerabilities and take screenshots of various control panels for later analysis. However, they do not adequately classify images into specific control groups, which is crucial for security-based tasks performed by manual operators. To solve this problem, we propose a pipeline based on deep learning to classify snapshots of industrial control panels into three categories: internet technologies, operation technologies, and others. More specifically, we compare the use of transfer learning and fine-tuning in convolutional neural networks (CNNs) pre-trained on ImageNet to select the best CNN architecture for classifying the screenshots of industrial control systems. We propose the critical infrastructure dataset (CRINF-300), which is the first publicly available information technology (IT)/operational technology (OT) snapshot dataset, with 337 manually labeled images. We used the CRINF-300 to train and evaluate eighteen different pipelines, registering their performance under CPU and GPU environments. We found out that the Inception-ResNet-V2 and VGG16 architectures obtained the best results on transfer learning and fine-tuning, with F1-scores of 0.9832 and 0.9373, respectively. In systems where time is critical and the GPU is available, we recommend using the MobileNet-V1 architecture, with an average time of 0.03 s to process an image and with an F1-score of 0.9758.

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Robertsson, Johan O. A., Fredrik Andersson, and René-Édouard Plessix. "Efficient snapshot-free reverse time migration and computation of multiparameter gradients in full-waveform inversion." GEOPHYSICS 86, no. 5 (July 27, 2021): T305—T320. http://dx.doi.org/10.1190/geo2020-0606.1.

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Computing images in reverse time migration and model parameter gradients from adjoint wavefields in full-waveform inversion (FWI) requires the correlation of a forward-propagated wavefield with another reverse-propagated wavefield. Although in theory only two wavefield propagations are required, one forward propagation and one reverse propagation, it requires storing the forward-propagated wavefield as a function of time to carry out the correlations, which is associated with significant input/output (I/O) cost. Alternatively, three wavefield propagations can be carried out to reverse propagate the forward-propagated wavefield in tandem with the reverse-propagated wavefield. We have determined how highly accurate reverse time migrated images and FWI model parameter gradients for anisotropic elastic FWI can be efficiently computed without significant disk I/O using two wavefield propagations by means of the principle of superposition.

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Yue, Jibo, Haikuan Feng, Xiuliang Jin, Huanhuan Yuan, Zhenhai Li, Chengquan Zhou, Guijun Yang, and Qingjiu Tian. "A Comparison of Crop Parameters Estimation Using Images from UAV-Mounted Snapshot Hyperspectral Sensor and High-Definition Digital Camera." Remote Sensing 10, no. 7 (July 18, 2018): 1138. http://dx.doi.org/10.3390/rs10071138.

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Timely and accurate estimates of crop parameters are crucial for agriculture management. Unmanned aerial vehicles (UAVs) carrying sophisticated cameras are very pertinent for this work because they can obtain remote-sensing images with higher temporal, spatial, and ground resolution than satellites. In this study, we evaluated (i) the performance of crop parameters estimates using a near-surface spectroscopy (350~2500 nm, 3 nm at 700 nm, 8.5 nm at 1400 nm, 6.5 nm at 2100 nm), a UAV-mounted snapshot hyperspectral sensor (450~950 nm, 8 nm at 532 nm) and a high-definition digital camera (Visible, R, G, B); (ii) the crop surface models (CSMs), RGB-based vegetation indices (VIs), hyperspectral-based VIs, and methods combined therefrom to make multi-temporal estimates of crop parameters and to map the parameters. The estimated leaf area index (LAI) and above-ground biomass (AGB) are obtained by using linear and exponential equations, random forest (RF) regression, and partial least squares regression (PLSR) to combine the UAV based spectral VIs and crop heights (from the CSMs). The results show that: (i) spectral VIs correlate strongly with LAI and AGB over single growing stages when crop height correlates positively with AGB over multiple growth stages; (ii) the correlation between the VIs multiplying crop height and AGB is greater than that between a single VI and crop height; (iii) the AGB estimate from the UAV-mounted snapshot hyperspectral sensor and high-definition digital camera is similar to the results from the ground spectrometer when using the combined methods (i.e., using VIs multiplying crop height, RF and PLSR to combine VIs and crop heights); and (iv) the spectral performance of the sensors is crucial in LAI estimates (the wheat LAI cannot be accurately estimated over multiple growing stages when using only crop height). The LAI estimates ranked from best to worst are ground spectrometer, UAV snapshot hyperspectral sensor, and UAV high-definition digital camera.

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Olesik, John W., Jeffery A. Kinzer, and Garrett J. McGowan. "Observation of Atom and Ion Clouds Produced from Single Droplets of Sample in Inductively Coupled Plasmas by Optical Emission and Laser-Induced Fluorescence Imaging." Applied Spectroscopy 51, no. 5 (May 1997): 607–16. http://dx.doi.org/10.1366/0003702971940909.

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An instrument to obtain optical emission and laser-induced fluorescence images of atom or ion clouds, each produced from isolated, monodisperse droplets of sample in an inductively coupled plasma, is described. An excimer laser pumped dye laser is used to produce a large (28-mm × 24-mm) beam for saturated fluorescence from atoms or ions throughout a large portion of the ICP. An intensified charge-coupled device (ICCD) detects optical emission or laser induced fluorescence snapshot images at the focal plane of an aberration-corrected slitless spectrograph. Images produced from a single laser pulse can be detected. Double-exposure emission images with 1-μs gate times can be acquired to monitor the movement of atom or ion clouds produced from a single droplet of sample solution. Variations in the number of atoms or ions produced as a function of time (or height) in the plasma can be monitored. Excitation in the plasma can be assessed from ratios of emission to fluorescence intensities.

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Mihoubi, Sofiane, Pierre-Jean Lapray, and Laurent Bigué. "Survey of Demosaicking Methods for Polarization Filter Array Images." Sensors 18, no. 11 (October 30, 2018): 3688. http://dx.doi.org/10.3390/s18113688.

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Snapshot polarization imaging has gained interest in the last few decades. Recent research and technology achievements defined the polarization Filter Array (PFA). It is dedicated to division-of-focal plane polarimeters, which permits to analyze the direction of light electric field oscillation. Its filters form a mosaicked pattern, in which each pixel only senses a fraction of the total polarization states, so the other missing polarization states have to be interpolated. As for Color or Spectral Filter Arrays (CFA or SFA), several dedicated demosaicking methods exist in the PFA literature. Such methods are mainly based on spatial correlation disregarding inter-channel correlation. We show that polarization channels are strongly correlated in images. We therefore propose to extend some demosaicking methods from CFA/SFA to PFA, and compare them with those that are PFA-oriented. Objective and subjective analysis show that the pseudo panchromatic image difference method provides the best results and can be used as benchmark for PFA demosaicking.

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Kvitka, V. E. "Simulation and Prototyping of an Orbital Lightning Detector." Herald of the Bauman Moscow State Technical University. Series Instrument Engineering, no. 3 (132) (September 2020): 4–17. http://dx.doi.org/10.18698/0236-3933-2020-3-4-17.

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The problem of detecting lightning flashes from space is becoming more and more important as the remote sensing of Earth, climatology and atmospheric physics develop. Orbital lightning detectors are designed both in Russia and abroad. The paper considers the problem of mathematical and physical simulation of a high-speed camera designed to observe lightning flashes from onboard spacecraft in low Earth orbit. Our previous works substantiated the exterior design of the lightning detector, computed its properties and described the algorithms behind the software. In order to validate the design results, we need to prototype the instrument. We describe the main problems of detecting lightning flashes as observed from space. We show a computer simulation method producing snapshots that takes into account the interference generated by the background and the photodetector. We studied the problems of recreating the target environment during prototyping of the lightning detector, accounting for the properties of the phenomenon observed, that is, the flash spot dimensions and the ratio of the background brightness to that of the lightning. We describe the principle of comparing these two types of snapshots (taken by the prototype and synthesised by the software) and compared the results of processing the images obtained. The results matched, which allowed us to validate the snapshot processing algorithm and confirmed that the lightning detector simulation method developed is correct

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Tsagkatakis, G., S. Nikolidakis, E. Petra, A. Kapantagakis, K. Grigorakis, G. Katselis, N. Vlahos, and P. Tsakalides. "Fish Freshness Estimation though analysis of Multispectral Images with Convolutional Neural Networks." Electronic Imaging 2020, no. 12 (January 26, 2020): 171–1. http://dx.doi.org/10.2352/issn.2470-1173.2020.12.fais-171.

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Quantification of food quality is a critical process for ensuring public health. Fish correspond to a particularly challenging case due to its high perishable nature as food. Existing approaches require laboratory testing, a laborious and timeconsuming process. In this paper, we propose a novel approach for evaluating fish freshness by exploiting the information encoded in the spectral profile acquired by a snapshot spectral camera. To extract the relevant information, we employ state-ofthe- art Convolutional Neural Networks and treat the problem as an instance of multi-class classification, where each class corresponds to a two-day period since harvesting. Experimental evaluation on individuals from the Sparidae (Boops sp.) family demonstrates that the proposed approach constitutes a valid methodology, offering both accuracy as well as effortless application.

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Beyerlein, Kenneth R., Thomas A. White, Oleksandr Yefanov, Cornelius Gati, Ivan G. Kazantsev, Nicolai Fog-Gade Nielsen, Peter M. Larsen, Henry N. Chapman, and Søren Schmidt. "FELIX: an algorithm for indexing multiple crystallites in X-ray free-electron laser snapshot diffraction images." Journal of Applied Crystallography 50, no. 4 (July 7, 2017): 1075–83. http://dx.doi.org/10.1107/s1600576717007506.

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A novel algorithm for indexing multiple crystals in snapshot X-ray diffraction images, especially suited for serial crystallography data, is presented. The algorithm, FELIX, utilizes a generalized parametrization of the Rodrigues–Frank space, in which all crystal systems can be represented without singularities. The new algorithm is shown to be capable of indexing more than ten crystals per image in simulations of cubic, tetragonal and monoclinic crystal diffraction patterns. It is also used to index an experimental serial crystallography dataset from lysozyme microcrystals. The increased number of indexed crystals is shown to result in a better signal-to-noise ratio, and fewer images are needed to achieve the same data quality as when indexing one crystal per image. The relative orientations between the multiple crystals indexed in an image show a slight tendency of the lysozme microcrystals to adhere on (\overline 110) facets.

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Minns, A. R., J. M. Riley, P. J. Warner, M. J. Rioja, and H. J. A. Röttgering. "The Nature of a Homogeneous Sample of Compact Radio Sources Variable at 151 MHz." International Astronomical Union Colloquium 164 (1998): 281–82. http://dx.doi.org/10.1017/s0252921100045565.

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AbstractGlobal VLBI snapshot observations at 1.6 GHz (5 EVN + 4 VLBA) of a sample of low-frequency variable (LFV) radio sources found using the Cambridge Low Frequency Synthesis Telescope (CLFST) are presented. Variability at 151 MHz is almost certainly due to propagation effects in our Galaxy (e.g., refractive interstellar scintillation). Theory indicates that only sources with a significant fraction of their low-frequency flux coming from components with angular sizes ≲ 30 mas will show such effects. This is confirmed by the VLBI images.

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Schambach, Maximilian, and Fernando Puente León. "Reconstruction of multispectral images from spectrally coded light fields of flat scenes." tm - Technisches Messen 86, no. 12 (November 18, 2019): 758–64. http://dx.doi.org/10.1515/teme-2019-0103.

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AbstractWe present a novel method to reconstruct multispectral images of flat objects from spectrally coded light fields as taken by an unfocused light field camera with a spectrally coded microlens array. In this sense, the spectrally coded light field camera is used as a multispectral snapshot imager, acquiring a multispectral datacube in a single exposure. The multispectral image, corresponding to the light field’s central view, is reconstructed by shifting the spectrally coded subapertures onto the central view according to their respective disparity. We assume that the disparity of the scene is approximately constant and non-zero. Since the spectral mask is identical for all subapertures, the missing spectral data of the central view will be filled up from the shifted spectrally coded subapertures. We investigate the reconstruction quality for different spectral masks and camera parameter sets optimized for real life applications such as in-line production monitoring for which the constant disparity constraint naturally holds. For synthesized reference scenes, using 16 color channels, we achieve a reconstruction \mathrm{PSNR} of up to 51 dB.

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Menon, Rajiv G., Edward G. Walsh, Donald B. Twieg, Charles G. Cantrell, Parmede Vakil, Sumeeth V. Jonathan, Hunt H. Batjer, and Timothy J. Carroll. "Snapshot MR Technique to Measure OEF Using Rapid Frequency Mapping." Journal of Cerebral Blood Flow & Metabolism 34, no. 7 (April 23, 2014): 1111–16. http://dx.doi.org/10.1038/jcbfm.2014.59.

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Magnetic resonance (MR)-based oxygen extraction fraction (OEF) measurement techniques that use blood oxygen level-dependent (BOLD)-based approaches require the measurement of the R2′ decay rate and deoxygenated blood volume to derive the local oxygen saturation in vivo. We describe here a novel approach to measure OEF using rapid local frequency mapping. By modeling the MR decay process in the static dephasing regime as two separate dissipative and oscillatory effects, we calculate the OEF from local frequencies measured across the brain by assuming that the biophysical mechanisms causing OEF-related frequency changes can be determined from the oscillatory effects. The Parameter Assessment by Retrieval from Signal Encoding (PARSE) technique was used to acquire the local frequency change maps. The PARSE images were taken on 11 normal volunteers, and 1 patient exhibiting hemodynamic stress. The mean MR-OEF in 11 normal subjects was 36.66 ± 7.82%, in agreement with positron emission tomography (PET) literature. In regions of hemodynamic stress induced by vascular steal, OEF exhibits the predicted focal increases. These preliminary results show that it is possible to measure OEF using a rapid frequency mapping technique. Such a technique has numerous advantages including speed of acquisition, is noninvasive, and has sufficient spatial and temporal resolution.

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Zhu, Jianchen, Shengjie Zhao, and Di Wu. "Classification of Remote Sensing Images Through Reweighted Sparse Subspace Representation Using Compressed Data." Traitement du Signal 38, no. 1 (February 28, 2021): 27–37. http://dx.doi.org/10.18280/ts.380103.

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In many real-world scenarios, subspace clustering essentially aims to cluster unlabeled high-dimensional data into a union of finite-dimensional linear subspaces. The problem is that the data are always high-dimensional, with the increase of the computation, storge, and communication of various intelligent data-driven systems. This paper attempts to develop a method to cluster spectral images directly using the measurements of compressive coded aperture snapshot spectral imager (CASSI), eliminating the need to reconstruct the entire data cube. Assuming that compressed measurements are drawn from multiple subspaces, a novel algorithm was developed by solving a 1-norm minimization problem, which is known as reweighted sparse subspace clustering (RSSC). The proposed algorithm clusters the compressed measurements into different subspaces, which greatly improves the clustering accuracy over the SSC algorithm by adding a reweighted step. The compressed CASSI measurements obtained using the coherence-based coded aperture can improve the performance of the proposed spectral image clustering method. The accuracy of our spectral image clustering approach was verified through simulations on two real datasets.

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Thorsen, Sofie, and Cecilie Astrupgaard. "Bridging the computational and visual turn: Re-tooling visual studies with image recognition and network analysis to study online climate images." Nordic Journal of Media Studies 3, no. 1 (June 1, 2021): 141–63. http://dx.doi.org/10.2478/njms-2021-0008.

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Abstract In this article, we argue that to capture the liveliness of how visual public debates like the climate controversy unfold online, we must replace snapshot and single-platform approaches with a method that can capture their temporal and cross-platform dynamics. We suggest that such a methodology could be assembled by combining image recognition, visual network analysis, and a quali-quantitative approach within a digital methods framework. We demonstrate the potential application of the methodology in a two-fold case study of 1) how the human–nature relation is visually depicted on Instagram and Twitter, and 2) how visual genres in the climate debate on Twitter change from 2015 to 2017. Through these experiments, we analyse more than a quarter million social media images to produce novel insights about the climate debate, while showcasing how the computational and visual capabilities of social science can be bridged to open up opportunities for mapping complex visual debates across platforms and time.

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Noskov, Mikhail, and Valeriy Tutatchikov. "Application of two-dimensional fast Fourier transform algorithm, analog of the Cooley-Tukey algorithm, for 4k fixed format digital image of satellite data in frequency domain processing." E3S Web of Conferences 149 (2020): 02010. http://dx.doi.org/10.1051/e3sconf/202014902010.

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Currently, digital images in the format Full HD (1920 * 1080 pixels) and 4K (4096 * 3072) are widespread. This article will consider the option of processing a similar image in the frequency domain. As an example, take a snapshot of the earth's surface. The discrete Fourier transform will be computed using a two-dimensional analogue of the Cooley-Tukey algorithm and in a standard way by rows and columns. Let us compare the required number of operations and the results of a numerical experiment. Consider the examples of image filtering.

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Gupta, Pooja, and Kuldip Pahwa. "Clock Algorithm Analysis for Increasing Quality of Digital Images." International Journal of Image and Graphics 16, no. 03 (July 2016): 1650016. http://dx.doi.org/10.1142/s0219467816500169.

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A digital image is not an exact snapshot of reality; it is only a discrete approximation. Thus, the captured images are always bit different from the images actually perceived by human eyes. These variations occur due to varying lighting conditions, weathers conditions like rain and fog, distance of scene from camera, image capturing angle, etc. The problem becomes more severe if these images are captured using low resolution image capturing devices like: Mobile phones, CCTV Cameras, Webcam, VGA cameras etc. Image enhancement addresses a solution of generating a high quality image from its low contrast version. Color enhancement is a process that differentiates objects in an image; as well as provides the detailed information of that image. This paper proposes color enhancement of low resolution digital images using clock algorithm. It is claimed that the proposed clock algorithm employed here produces good quality images in comparison with the existing color enhancement techniques. The simulation results proved that the proposed clock algorithm efficiently enhances the quality of digital low resolution images and analytically their quality improvement is observed in terms of peak signal to noise ratio (PSNR), mean square error (MSE) and bit error rate (BER) over the existing color enhancement techniques.

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Tamkhane, Bipin D. "A Survey on Intensification Techniques used in Satellite Images." International Journal for Research in Applied Science and Engineering Technology 9, no. VII (July 25, 2021): 2242–45. http://dx.doi.org/10.22214/ijraset.2021.36873.

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An image intensification is a required methodology in field of Satellite image research area. The images taken through satellite are captured from very longer distance and because of this images having garbling and noise as lots of airy barriers are present in between the path. The usage of Satellite images is very diverse in research areas like astrological studies, geographical studies, study of geoscience, etc. Nowadays, after taking a snapshot of an image, some of the radiometric or geometric based enhancement techniques are applied on the images taken from satellite but these techniques do not fulfill the requirements in all application areas. This is what there is a need to improvise the quality of an image before it is being actually used. The main objective behind this research work is to understand the different methodologies used in intensification of satellite images and how can we perform more improvements to existing techniques so these type of images which are taken from satellite are intelligible to the human eyes. The meaning of intensification in term of image is nothing but the altering of a look and feel of the image in a way that the information contained by that image is more readily intelligible visually.

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Zhao, Xiao-Ying, Xiao-Hu Li, Jian Song, Bin Liu, and Xing-Wang Wu. "The SnapShot Freeze Algorithm Improves Image Quality of Coronary Computed Tomography Angiography Using High-Resolution Wide-Detector CT." Journal of Medical Imaging and Health Informatics 9, no. 8 (October 1, 2019): 1681–85. http://dx.doi.org/10.1166/jmihi.2019.2789.

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Objective: The aim of this study was to investigate the effect the motion-correction reconstruction algorithm SnapShot Freeze (SSF) on the diagnostic performance of coronary computed tomography angiography (CCTA) using high-resolution, wide-detector CT. Methods: CCTA was performed using an electrocardiography-triggered auto-gating protocol in 62 patients. All images were reconstructed using both standard algorithm and motioncorrection algorithm (SSF). According to the American Heart Association (AHA) guidelines for coronary angiography, the coronary artery was divided into 15 segments. The coronary artery segments were evaluated using a 4-point Likert scale to determine the image quality. Arteries with a score greater than 1 were further evaluated by two expert radiologists blinded to conditions. The diagnostic performance of SSF was compared in the patients with high heart rate (HR ≥ 75 beats per minute) compared to low HR (< 75 beats per minute). Results: At the segmental level, the Likert score for segments 1–4 and 6–14 were higher in SSF compared to standard algorithm (p < 0.05). The proportion of images that was improved by SSF was greater for the high HR systolic phase imaging (66.7%) than for the low HR diastolic phase imaging (34.3%, p < 0.05). Conclusion: The SSF algorithm improves coronary CTA images acquired using a 256-row wide detector CT, compared to standard algorithm, particularly in patients with high HR.

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Lei, Hongxia, Vladimir Mlynárik, Nathalie Just, and Rolf Gruetter. "Snapshot gradient-recalled echo-planar images of rat brains at long echo time at 9.4 T." Magnetic Resonance Imaging 26, no. 7 (September 2008): 954–60. http://dx.doi.org/10.1016/j.mri.2008.01.009.

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Matthaei, Dieter, Axel Haase, Dietmar Henrich, and Eckhart Dühmke. "Fast inversion recovery T1 contrast and chemical shift contrast in high-resolution Snapshot FLASH MR images." Magnetic Resonance Imaging 10, no. 1 (January 1992): 1–6. http://dx.doi.org/10.1016/0730-725x(92)90366-8.

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Rowlinson, A., R. L. C. Starling, K. Gourdji, G. E. Anderson, S. ter Veen, S. Mandhai, R. A. M. J. Wijers, T. W. Shimwell, and A. J. van der Horst. "LOFAR early-time search for coherent radio emission from short GRB 181123B." Monthly Notices of the Royal Astronomical Society 506, no. 4 (July 21, 2021): 5268–77. http://dx.doi.org/10.1093/mnras/stab2060.

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ABSTRACT The mergers of two neutron stars are typically accompanied by broad-band electromagnetic emission from either a relativistic jet or a kilonova. It has also been long predicted that coherent radio emission will occur during the merger phase or from a newly formed neutron star remnant; however, this emission has not been seen to date. This paper presents the deepest limits for this emission from a neutron star merger, following triggered LOFAR observations of the short gamma-ray burst 181123B, starting 4.4 min after the GRB occurred. During the X-ray plateau phase, a signature of ongoing energy injection, we detect no radio emission to a 3σ limit of 153 mJy at 144 MHz (image integration time of 136 s), which is significantly fainter than the predicted emission from a standard neutron star. At a redshift of 1.8, this corresponds to a luminosity of 2.5 × 1044 erg s−1. Snapshot images were made of the radio observation on a range of time-scales, targeting short-duration radio flashes similar to fast radio bursts. No emission was detected in the snapshot images at the location of GRB 181123B enabling constraints to be placed on the prompt coherent radio emission model and emission predicted to occur when a neutron star collapses to form a black hole. At the putative host redshift of 1.8 for GRB 181123B, the non-detection of the prompt radio emission is two orders of magnitude lower than expected for magnetic reconnection models for prompt GRB emission and no magnetar emission is expected.

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Nindos, A., C. E. Alissandrakis, T. S. Bastian, S. Patsourakos, B. De Pontieu, H. Warren, T. Ayres, et al. "First high-resolution look at the quiet Sun with ALMA at 3mm." Astronomy & Astrophysics 619 (November 2018): L6. http://dx.doi.org/10.1051/0004-6361/201834113.

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We present an overview of high-resolution quiet Sun observations, from disk center to the limb, obtained with the Atacama Large millimeter and sub-millimeter Array (ALMA) at 3 mm. Seven quiet-Sun regions were observed at a resolution of up to 2.5″ by 4.5″. We produced both average and snapshot images by self-calibrating the ALMA visibilities and combining the interferometric images with full-disk solar images. The images show well the chromospheric network, which, based on the unique segregation method we used, is brighter than the average over the fields of view of the observed regions by ∼305 K while the intranetwork is less bright by ∼280 K, with a slight decrease of the network/intranetwork contrast toward the limb. At 3 mm the network is very similar to the 1600 Å images, with somewhat larger size. We detect, for the first time, spicular structures, rising up to 15″ above the limb with a width down to the image resolution and brightness temperature of ∼1800 K above the local background. No trace of spicules, either in emission or absorption, is found on the disk. Our results highlight the potential of ALMA for the study of the quiet chromosphere.

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Xie, Jiangjian, Anqi Li, Junguo Zhang, and Zhean Cheng. "An Integrated Wildlife Recognition Model Based on Multi-Branch Aggregation and Squeeze-And-Excitation Network." Applied Sciences 9, no. 14 (July 12, 2019): 2794. http://dx.doi.org/10.3390/app9142794.

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Infrared camera trapping, which helps capture large volumes of wildlife images, is a widely-used, non-intrusive monitoring method in wildlife surveillance. This method can greatly reduce the workload of zoologists through automatic image identification. To achieve higher accuracy in wildlife recognition, the integrated model based on multi-branch aggregation and Squeeze-and-Excitation network is introduced. This model adopts multi-branch aggregation transformation to extract features, and uses Squeeze-and-Excitation block to adaptively recalibrate channel-wise feature responses based on explicit self-mapped interdependencies between channels. The efficacy of the integrated model is tested on two datasets: the Snapshot Serengeti dataset and our own dataset. From experimental results on the Snapshot Serengeti dataset, the integrated model applies to the recognition of 26 wildlife species, with the highest accuracies in Top-1 (when the correct class is the most probable class) and Top-5 (when the correct class is within the five most probable classes) at 95.3% and 98.8%, respectively. Compared with the ROI-CNN algorithm and ResNet (Deep Residual Network), on our own dataset, the integrated model, shows a maximum improvement of 4.4% in recognition accuracy.

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Diaz, Nelson Eduardo, Hoover Fabian Rueda Chacon, and Henry Arguello Fuentes. "High-dynamic range compressive spectral imaging by grayscale coded aperture adaptive filtering." Ingeniería e Investigación 35, no. 3 (December 14, 2015): 53–60. http://dx.doi.org/10.15446/ing.investig.v35n3.49868.

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The coded aperture snapshot spectral imaging system (CASSI) is an imaging architecture which senses the three dimensional informa-tion of a scene with two dimensional (2D) focal plane array (FPA) coded projection measurements. A reconstruction algorithm takes advantage of the compressive measurements sparsity to recover the underlying 3D data cube. Traditionally, CASSI uses block-un-block coded apertures (BCA) to spatially modulate the light. In CASSI the quality of the reconstructed images depends on the design of these coded apertures and the FPA dynamic range. This work presents a new CASSI architecture based on grayscaled coded apertu-res (GCA) which reduce the FPA saturation and increase the dynamic range of the reconstructed images. The set of GCA is calculated in a real-time adaptive manner exploiting the information from the FPA compressive measurements. Extensive simulations show the attained improvement in the quality of the reconstructed images when GCA are employed. In addition, a comparison between traditional coded apertures and GCA is realized with respect to noise tolerance.

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Correa Pugliese, Claudia Victoria, Diana Fernanda Galvis Carreño, and Henry Arguello Fuentes. "Sparse representations of dynamic scenes for compressive spectral video sensing." DYNA 83, no. 195 (February 23, 2016): 42–51. http://dx.doi.org/10.15446/dyna.v83n195.47873.

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The coded aperture snapshot spectral imager (CASSI) is an optical architecture that captures spectral images using compressive sensing. This system improves the sensing speed and reduces the large amount of collected data given by conventional spectral imaging systems. In several applications, it is necessary to analyze changes that occur between short periods of time. This paper first presents a sparsity analysis for spectral video signals, to obtain accurate approximations and better comply compressed sensing theory. The use of the CASSI system in compressive spectral video sensing then is proposed. The main goal of this approach is to capture the spatio-spectral information of dynamic scenes using a 2-dimensional set of projections. This application involves the use of a digital micro-mirror device that implements the traditional coded apertures used by CASSI. Simulations show that accurate reconstructions along the spatial, spectral and temporal axes are attained, with PSNR values of around 30 dB.

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Journal articles on the topic 'Snapshot images'

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