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Literatura académica sobre el tema "Reconstruction de pixel"

Autor: Grafiati

Publicado: 25 de mayo de 2024

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Artículos de revistas sobre el tema "Reconstruction de pixel"

Rymarczyk, Tomasz y Grzegorz Kłosowski. "Identification of moisture inside walls in buildings using machine learning and ensemble methods". International Journal of Applied Electromagnetics and Mechanics 69, n.º 3 (5 de julio de 2022): 375–88. http://dx.doi.org/10.3233/jae-210176.

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According to the article, locating moisture within the walls of buildings using electrical impedance tomography is discussed in detail. The algorithmic approach, whose role is to convert the input measurements into images, received excellent attention during the development process. Numerous models have been trained to generate tomographic images based on individual pixels in a given image based on machine learning methods. An array of categorisation data was then generated, which enabled the development of a classification model to solve the problem of optimal model selection for a given point on the screen. It was achieved in this manner by developing a pixel-oriented ensemble model (POE), the goal of which is to provide tomographic reconstructions of at least the same quality as homogeneous algorithmic approaches. Artificial neural networks (ANN), linear regression (LR), and the long short-term memory network (LSTM) were employed in the current research to get homogeneous machine learning results. An image reconstruction algorithm such as the ANN or the LR reconstructs the image pixel by pixel, which means that a different prediction model is trained for each image pixel. In the case of LSTM, a single network is responsible for creating the entire image. Then, using the POE algorithm, the best reconstruction method was fitted to each pixel of the output image while considering the measurement scenario provided to the program. As a result, each measurement consequences in a unique assignment of reconstructive procedures to individual pixels, which is different for each measurement. It is the capacity to maximise the selection of a prediction model while considering both a given pixel and a specific measurement vector that distinguishes the provided POE concept from other approaches.

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Mantripragada, Kiran, Phuong D. Dao, Yuhong He y Faisal Z. Qureshi. "The effects of spectral dimensionality reduction on hyperspectral pixel classification: A case study". PLOS ONE 17, n.º 7 (14 de julio de 2022): e0269174. http://dx.doi.org/10.1371/journal.pone.0269174.

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This paper presents a systematic study of the effects of hyperspectral pixel dimensionality reduction on the pixel classification task. We use five dimensionality reduction methods—PCA, KPCA, ICA, AE, and DAE—to compress 301-dimensional hyperspectral pixels. Compressed pixels are subsequently used to perform pixel classifications. Pixel classification accuracies together with compression method, compression rates, and reconstruction errors provide a new lens to study the suitability of a compression method for the task of pixel classification. We use three high-resolution hyperspectral image datasets, representing three common landscape types (i.e. urban, transitional suburban, and forests) collected by the Remote Sensing and Spatial Ecosystem Modeling laboratory of the University of Toronto. We found that PCA, KPCA, and ICA post greater signal reconstruction capability; however, when compression rates are more than 90% these methods show lower classification scores. AE and DAE methods post better classification accuracy at 95% compression rate, however their performance drops as compression rate approaches 97%. Our results suggest that both the compression method and the compression rate are important considerations when designing a hyperspectral pixel classification pipeline.

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Hirata, Christopher M. y Christopher Merchant. "Pixel Centroid Characterization with Laser Speckle and Application to the Nancy Grace Roman Space Telescope Detector Arrays". Publications of the Astronomical Society of the Pacific 134, n.º 1041 (1 de noviembre de 2022): 115001. http://dx.doi.org/10.1088/1538-3873/ac99fe.

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Abstract The Nancy Grace Roman Space Telescope will use its wide-field instrument to carry out a suite of sky surveys in the near-infrared. Several of the science objectives of these surveys, such as the measurement of the growth of cosmic structure using weak gravitational lensing, require exquisite control of instrument-related distortions of the images of astronomical objects. Roman will fly new large-format (4 × 4 k) Teledyne H4RG-10 infrared detector arrays. This paper investigates whether the pixel centroids are located on a regular grid by projecting laser speckle patterns through a double slit aperture onto a non-flight detector array. We develop a method to reconstruct the pixel centroid offsets from the stochastic speckle pattern. Due to the orientation of the test setup, only x-offsets are measured here. We test the method both on simulations, and by injecting artificial offsets into the real images. We use cross-correlations of the reconstructions from different speckle realizations to determine how much of the variance in the pixel offset maps is signal (fixed to the detector) and how much is noise. After performing this reconstruction on 64 × 64 pixel patches, and fitting out the best-fit linear mapping from pixel index to position, we find that there are residual centroid offsets in the x (column) direction from a regular grid of 0.0107 pixels rms (excluding shifts of an entire row relative to another, which our speckle patterns cannot constrain). This decreases to 0.0097 pix rms if we consider residuals from a quadratic rather than linear mapping. These rms offsets include both the physical pixel offsets, as well as any apparent offsets due to crosstalk and remaining systematic errors in the reconstruction. We comment on the advantages and disadvantages of speckle scene measurements as a tool for characterizing the pixel-level behavior in astronomical detectors.

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Ahmed, Ansari Vaqar y Uday Pandit Khot. "An Efficient Motion Vector Recovery and Reconstruction Method for Spatiotemporal Video Error Concealment". International Journal of Computer Vision and Image Processing 9, n.º 4 (octubre de 2019): 28–48. http://dx.doi.org/10.4018/ijcvip.2019100103.

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In this article, an efficient spatiotemporal video error concealment (EC) based on motion vector (MV) recovery and a pixel reconstruction (PR) method is proposed. The pixel-based motion vector with partition (PMVP) is modified by using Mahalanobis distance (MD) rather than Euclidean distance (ED) for recovering MVs, as MD uses standard deviation and covariance of available pixels. Further, the MD gives more accuracy for non-square cluster compared to ED. This modified pixel-based motion vector with partition (MPMVP) algorithm is further upgrade by two different strategies. First, by using voting priority of available MVs based on the probabilities of similar directions. Second, by considering separate horizontal and vertical directions of available MVs in voting priority. For pixel reconstruction, modified spiral pixel reconstruction (MSPR) algorithm based on directional edge recovery method using minimum and maximum Mahalanobis distance from available pixels of surrounding MBs is proposed. Mahalanobis distance approach is most optimized similarity measure technique compared to other distance measurement approach to obtained lost motion vectors. These proposed EC techniques are compared with existing EC techniques like, SPR EC using ED, PMVP based EC with ED, and MV Interpolation by Zhou's method for various packet loss rates (PLRs) as 3%, 7%, 16%, 20% and quantization parameters (QPs) as 20, 24, 28, 32, 36. For total average in PLR of 3%, 7%, 16% and 20%, MSPR is having better PSNR compared to PMVP by 2.516, 2.29, 2.06 and 2.02 dB, respectively; and compared to SPR by 0.796, 0.718, 0.643 and 0.631 dB, respectively.

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Irum, Isma, Muhammad Sharif, Mussarat Yasmin, Mudassar Raza y Faisal Azam. "A Noise Adaptive Approach to Impulse Noise Detection and Reduction". Nepal Journal of Science and Technology 15, n.º 1 (2 de febrero de 2015): 67–76. http://dx.doi.org/10.3126/njst.v15i1.12016.

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A noise adaptive filter has been proposed in this study aiming to estimate the original image pixel values in the presence of impulse noise in monochromatic images. The proposed filter approach is noise adaptive that as the percentage of noise density increases in the image, the size of neighborhood in filtering window is also increased. Proposed approach comprises of two stages, one is impulse noise detection and the other is impulse noise reduction or cancellation. First stage is based on median and mean distance and thresholding whereas the second stage is based on reconstruction of the image using the values of neighboring pixels of the pixel under consideration detected as contaminated pixel by first stage. Reconstruction is done by estimating reference values using uncorrupted pixels in the neighborhood of pixel under consideration. The proposed method has been compared to various existing methods by using peak signal to noise ratio (PSNR) for measuring the objective quality strength. To measure the impulse noise detection the method has also been compared with other existing methods using the ratio of mis etection (MD) and false detection (FD).DOI: http://dx.doi.org/10.3126/njst.v15i1.12016 Nepal Journal of Science and TechnologyVol. 15, No.1 (2014) 67-76

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Tian, Y., W. Zhou, Q. Wang, X. Niu, W. Han, H. Yang, H. Zhang, S. Liao, X. Li y C. Zhao. "A novel silicon pixel sensor for beam monitoring applications at heavy-ion accelerators". Journal of Instrumentation 19, n.º 04 (1 de abril de 2024): C04039. http://dx.doi.org/10.1088/1748-0221/19/04/c04039.

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Abstract This paper describes a silicon pixel sensor for non-interceptive real-time beam monitoring at heavy-ion accelerators. The total size of the sensor is 4 mm × 5 mm. It has 64 (row) × 120 (column) square pixels, each single of which is in the size of 40 μm × 40 μm. With the exposed sensing pad, this sensor can directly collect the charge in the media over the pixels. The in-pixel circuit mainly consists of a low-noise Charge Sensitive Amplifier (CSA) to establish the signal for the energy reconstruction and a discriminator with a Time-to-Amplitude Converter (TAC) for the Time of Arrival (TOA) measurement. The analog signal from each pixel is accessible through time-shared multiplexing over the entire pixel array. This paper will discuss the design of this IMPix-S1 sensor.

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Diógenes, A. N., L. O. E. Dos Santos, C. P. Fernandes, A. C. Moreira y C. R. Apolloni. "POROUS MEDIA MICROSTRUCTURE RECONSTRUCTION USING PIXEL-BASED AND OBJECT-BASED SIMULATED ANNEALING – COMPARISON WITH OTHER RECONSTRUCTION METHODS". Revista de Engenharia Térmica 8, n.º 2 (31 de diciembre de 2009): 35. http://dx.doi.org/10.5380/reterm.v8i2.61896.

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In this contribution the issue of the stochastic reconstruction of particulatemedia from 2D photomicrographic images is addressed with particular reference to pore space connectivity. The reconstruction of porous bodies in 2D or 3D space was achieved by using simulated annealing techniques. Two methods were proposed to reconstruct a well connected pore space. The first, named PSA (Pixel-based Simulated Annealing), a pixel-movement based, three constraints were found to be necessary for the successful reconstruction of well connected pore space: the two-pointcorrelation function, the d3-4 distance transform distribution and the linealpath function for the pore phase. The second, named OSA (Object-based Simulated Annealing), only constrains the two-point correlation function. Following several researches which tried to reconstruct porous media using pixel-movement based simulated techniques, we propose a new parameter to add a microstructure descriptor, but we also propose a new technique, based in moving the microstructure grains (spheres) instead of the pixels. Both methods were applied to reconstruct reservoir rocks microstructures, and the 2D and 3D results were compared with microstructures reconstructed by truncated Gaussian methods. The PSA resulted in microstructures characterized by poor pore space connectivity, and by artificial patterns, while the OSA reconstructed microstructures with good pore space connectivity. These results indicate that the OSA method can reconstruct better microstructures than the present methods.

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Fager, R. S., K. V. Peddanarappagari y G. N. Kumar. "Pixel-based reconstruction (PBR) promising simultaneous techniques for CT reconstructions". IEEE Transactions on Medical Imaging 12, n.º 1 (marzo de 1993): 4–9. http://dx.doi.org/10.1109/42.222660.

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Li, L., L. Zhang, J. N. Dong, J. Liu y M. Wang. "Characterization of a CMOS pixel sensor for charged particle tracking". Journal of Instrumentation 16, n.º 12 (1 de diciembre de 2021): P12016. http://dx.doi.org/10.1088/1748-0221/16/12/p12016.

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Abstract A prototype of the CMOS pixel sensor named Supix-1 has been fabricated and tested in order to investigate the feasibility of a pixelated tracker for a proposed Higgs factory, namely, the Circular Electron-Positron Collider (CEPC). The sensor, taped out with a 180 nm CMOS Image Sensor (CIS) process, consists of nine different pixel arrays varying in pixel pitches, diode sizes and geometries in order to study the particle detection performance of enlarged pixels. The test was carried out with a 55Fe radioactive source. Two soft X-ray peaks observed were used to calibrate the charge to voltage factor of the sensor. The pixel-wise equivalent noise charge, charge collection efficiency and signal-to-noise ratio were evaluated. A reconstruction method for clustering pixels of a signal has been developed and the cluster-wise performance was studied as well. The test results show that pixels with the area as large as of 21 × 84 μm have satisfactory noise level and charge collection performance, meeting general requirements for a pixel sensor. This contribution demonstrates that the CMOS pixel sensor with enlarged pitches, using the CIS technology, can be used in tracking for upcoming collider detectors akin to the CEPC.

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Wu, Wei, Luoqi Ge, Jiancheng Luo, Ruohong Huan y Yingpin Yang. "A Spectral–Temporal Patch-Based Missing Area Reconstruction for Time-Series Images". Remote Sensing 10, n.º 10 (28 de septiembre de 2018): 1560. http://dx.doi.org/10.3390/rs10101560.

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Clouds, cloud shadows (CCS), and numerous other factors will cause a missing data problem in passive remote sensing images. A well-known reconstruction method is the selection of a similar pixel (with an additional clear reference image) from the remaining clear part of an image to replace the missing pixel. Due to the merit of filling the missing value using a pixel acquired on the same image with the same sensor and the same date, this method is suitable for time-series applications when a time-series profile-based similar measure is utilized for selecting the similar pixel. Since the similar pixel is independently selected, the improper reference pixel or various accuracies obtained by different land covers causes the problem of salt-and-pepper noise in the reconstructed part of an image. To overcome these problems, this paper presents a spectral–temporal patch (STP)-based missing area reconstruction method for time-series images. First, the STP, the pixels of which have similar spectral and temporal evolution characteristics, is extracted using multi-temporal image segmentation. However, some STP have Missing Observations (STPMO) in the time series, which should be reconstructed. Next, for an STPMO, the most similar STP is selected as the reference STP; then, the mean and standard deviation of the STPMO is predicted using a linear regression method with the reference STP. Finally, the textural information, which is denoted by the spatial configuration of color or intensities of neighboring pixels, is extracted from the clear temporal-adjacent STP and “injected” into the missing area to obtain synthetic cloud-free images. We performed an STP-based missing area reconstruction experiment in Jiangzhou, Chongzuo, Guangxi with time-series images acquired by wide field view (WFV) onboard Chinese Gao Fen 1 on 12 different dates. The results indicate that the proposed method can effectively recover the missing information without salt-and-pepper noise in the reconstructed area; also, the reconstructed part of the image is consistent with the clear part without a false edge. The results confirm that the spectral information from the remaining clear part of the same image and textural information from the temporal-adjacent image can create seamless time-series images.

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Tesis sobre el tema "Reconstruction de pixel"

Liu, Yi Ph D. Massachusetts Institute of Technology. "Scanning-free compressive reconstruction of object motion with sub-pixel accuracy". Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/74924.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 55-57).
Sub-pixel movement detection is an under-sampling problem. The basic idea for successful detection is to spread out the information over a larger sampling region. Diffraction provides a natural way to spread out the information; however, conventional digital holographic methods are not effective for extracting sub-pixel accuracy. Here we show how to apply compressive reconstruction to the same problem effectively. Compressed sensing is a new framework to systematically find highly accurate solutions to an under-sampled linear system. To guarantee the accuracy of reconstruction result, compressed sensing requires that the unknown has to be sparse in some predetermined basis. In our study, for the one dimensional sub-pixel movement detection, we propose to use the derivative operator as the sparsifying basis. We implemented the derivative operator to the hologram and applied a sparsity constraint on the object derivative space for compressive holography. Together with spectrum domain zero-padding, our compressive algorithm allows for sub-pixel accuracy edge localization. The extension to the 2D case is not trivial. It has been shown that the spiral phase mask can serve as an approximate 2D derivative operator in the Fourier domain. In this case, we implemented spiral phase filtering in the hologram spectrum domain. By applying cross-correlation between reconstructions for consecutive subpixel movements, sub-pixel movement was successfully detected.
by Yi Liu.
S.M.

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Kawahara, Ryo. "A Novel Catadioptric Ray-Pixel Camera Model and its Application to 3D Reconstruction". Kyoto University, 2019. http://hdl.handle.net/2433/242435.

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Oja, Martin y Sebastian Olsson. "Stand-alone Dual Sensing Single Pixel Camera in SWIR". Thesis, Linköpings universitet, Fysik och elektroteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-158206.

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A Single pixel camera is just that, a camera that uses only a single pixel to take images. Though, it is a bit more to it than just a pixel. It requires several components which will be explained in the thesis. For it to be viable it also needs the sampling technology Compressive sensing which compresses the data in the sampling stage, thus reducing the amount of data required to be sampled in order to reconstruct an image. This thesis will present the method of building an SPC with the required hardware and software. Different types of experiments, such as detection of small changes in a scene and different wavelength bands, has been conducted in order to test the performance and application areas for the SPC. The resulting system is able to produce images of resolutions up to 512x512 pixels. Disturbances such as movement in the scene or the camera itself being shaken became less of a problem with the addition of a second pixel. This thesis proves that an SPC is a viable technology with many different areas of application and it is a relatively cheap way of making a camera for the infrared spectrum.

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Reidel, Claire-Anne. "Applications for CMOS pixel sensors in ion-beam therapy". Thesis, Strasbourg, 2020. https://publication-theses.unistra.fr/public/theses_doctorat/2020/REIDEL_Claire-Anne_2020_ED182.pdf.

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En hadronthérapie, des mesures de haute précision sont essentielles pour avoir une base de données robuste et délivrer le traitement prescrit au patient. Dans ce travail, un système de trajectométrie, composé de capteurs à pixels MIMOSA-28, a été utilisé pour différentes applications cliniques. Plusieurs améliorations ont été implémentées au niveau matériel et logiciel résultant à une résolution spatiale de trace < 10 μm. Les expériences ont été menées avec succès dans différents centres médicaux et de recherche. Les profils de faisceaux ont été mesurés et la largeur du faisceau le long de l'axe a pu être calculée grâce à un code de transport basé sur la diffusion. Un outil en ligne de suivi de faisceau a été développé pour avoir une information rapide de son profil. D'autre part, les perturbations de la fluence dues à des marqueurs de repères pour un faisceau 12C ont été évaluées. Après reconstruction et extrapolation de chaque trace, une distribution 3D de la fluence a pu être établie et la perturbation maximale de la fluence et sa position ont pu être quantifiées. Les points froids mesurés varient entre moins de 3% à 9.2% pour un marqueur et une énergie de faisceau définis
In ion-beam therapy, high precision measurements are essential for having robust basic data to deliver the prescribed treatment to the patient. In this study, MIMOSA-28 pixel sensors were used as a tracker system for different medical applications. Several hardware and software improvements were implemented leading to a spatial track resolution < 10 μm. The experiments were conducted with success in different medical and research facilities. In this work, beam profiles were measured along the beam axis and the width of the beam along the axis could be calculated with a transportation code based on multiple Coulomb scattering. Moreover, an online beam monitoring was developed in order to have fast information about the beam profile. In another study, the fluence perturbation of 12C ion beams due to small fiducial markers was investigated. After reconstruction and extrapolation of single track, a 3D fluence distribution could be performed and the maximum perturbation and its position along the beam axis could be quantified. In this work, the measured cold spot varied between less than 3% up to 9.2% for a defined marker and a defined primary energy beam

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Benitez, Mendieta Jessica. "An efficient and semiautomatic segmentation method for 3D surface reconstruction of the lumbar spine from Magnetic Resonance Imaging (MRI)". Thesis, Queensland University of Technology, 2016. https://eprints.qut.edu.au/101274/1/Jessica_Benitez%20Mendieta_Thesis.pdf.

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A new semiautomatic technique for the segmentation and reconstruction of 3D vertebral anatomy from MRI is presented where five cadaveric human lumbar spines and one ovine spine were used. The MR images were subjected to contrast enhancement, anisotropic diffusion filtering, and thresholding was selected as the preferable segmentation technique to create 3D surfaces from the MRI datasets. The reconstructions were manually cleaned using commercial software. The resulting reconstructed surface included discrete vertebral bodies with distinct separation between the spinous processes. CT reconstructions were used to assess the accuracy of the reconstructed spinal anatomy from MRI.

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Delestre, Barbara. "Reconstruction 3D de particules dans un écoulement par imagerie interférométrique". Electronic Thesis or Diss., Normandie, 2022. http://www.theses.fr/2022NORMR116.

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Pour de nombreuses applications industrielles ou environnementales, il est important de mesurer la taille et le volume de particules de formes irrégulières. C'est par exemple le cas dans le cadre du givrage des aéronefs qui se produit durant les vols, où il est nécessaire de mesurer in-situ la teneur en eau et la teneur en glace dans la troposphère afin de détecter et d’éviter les zones à risques. Notre intérêt s’est porté sur l’imagerie interférométrique en défaut de mise au point, une technique optique offrant de nombreux avantages (large champ de mesure, gamme de tailles étudiée étendue [50 μm : quelques millimètres], distance particule/appareil de mesure de plusieurs dizaines de centimètres…). Au cours de ces travaux de thèse, nous avons montré que la reconstruction 3D d'une particule peut se faire à partir d'un ensemble de trois images interférométriques de cette particule (sous trois angles de vue perpendiculaires). Cela peut être fait en utilisant l'algorithme de réduction d'erreur (ER) qui permet d'obtenir la fonction f(x,y) à partir des mesures du module de sa transformée de Fourier 2D |F(u,v)|, en reconstruisant la phase de sa transformée de Fourier 2D. La mise en œuvre de cet algorithme nous a permis de reconstruire la forme de particules irrégulières à partir de leurs images interférométriques. Des démonstrations expérimentales ont été réalisées à l'aide d'un montage spécifique basé sur l'utilisation d’une matrice de micro-miroirs (DMD) qui génère les images interférométriques de particules rugueuses programmables. Les résultats obtenus sont très encourageants. Les volumes obtenus restent assez proches du volume réel de la particule et les formes 3D reconstruites nous donnent une bonne idée de la forme générale de la particule étudiée même dans les cas les plus extrêmes où l'orientation de la particule est quelconque. Enfin, nous avons montré qu'une reconstruction 3D précise d'une particule rugueuse "programmée" peut être effectuée à partir d'un ensemble de 120 images interférométriques
For many industrial or environmental applications, it is important to measure the size and volume of irregularly shaped particles. This is for example the case in the context of aircraft icing which occurs during flights, where it is necessary to measure in situ the water content and the ice content in the troposphere in order to detect and avoid risk areas. Our interest has been on interferometric out-of-focus imaging, an optical technique offering many advantages (wide measurement field, extended range of sizes studied [50 μm: a few millimeters], distance particle / measuring device several tens of centimeters ...). During this thesis, we showed that the 3D reconstruction of a particle can be done from a set of three interferometric images of this particle (under three perpendicular viewing angles). This can be done using the error reduction (ER) algorithm which allows to obtain the function f(x,y) from the measurements of the modulus of its 2D Fourier transform |F(u,v)| , by reconstructing the phase of its 2D Fourier transform. The implementation of this algorithm allowed us to reconstruct the shape of irregular particles from their interferometric images. Experimental demonstrations were carried out using a specific assembly based on the use of a micro-mirror array (DMD) which generates the interferometric images of programmable rough particles. The results obtained are very encouraging. The volumes obtained remain quite close to the real volume of the particle and the reconstructed 3D shapes give us a good idea of the general shape of the particle studied even in the most extreme cases where the orientation of the particle is arbitrary. Finally, we showed that an accurate 3D reconstruction of a "programmed" rough particle can be performed from a set of 120 interferometric images

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Rebiere, Valentin. "Image processing for a RGB-Z mixed matrix". Electronic Thesis or Diss., Sorbonne université, 2021. http://www.theses.fr/2021SORUS468.

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Un système RGB-Z est un système de vision sur puce (V-SoC) qui capture à la fois les informations de couleur et de profondeur. Récemment, l’idée de combiner l’acquisition de la couleur et de la profondeur au niveau du pixel et dans la même matrice a émergé. Un tel capteur permettrait une intégration plus compacte tout en réduisant les problèmes de calibration par rapport à un système composés de deux capteurs. Cependant, une telle intégration soulève de nouvelles contraintes à différent niveaux techniques. Dans cette thèse, nous nous focalisons sur les problèmes de reconstruction de l'information de couleur manquante due à l'hétérogénéité de la matrice de pixels. Actuellement, il n'existe pas sur le marché de capteur RGB-Z monolithique tel que décrit dans la thèse. Dans un premier temps, nous avons proposé différentes matrices RGB-Z. Ces matrices sont basées sur deux architectures de pixels Z différentes. La distribution et la taille des pixels Z varient en fonction des matrices proposées. Dans un deuxième temps, plusieurs algorithmes de reconstruction de l’information manquante inspirés de l'état de l'art ont été adaptés et implémentés aux matrices proposées. Ces solutions ne sont pas satisfaisantes. Pour cela, un algorithme adaptatif pour reconstruire l'information de couleur manquante en utilisant un nouvel opérateur appelé semi-gradient est proposé. Cet opérateur permet de mieux reconstruire les structures situées le long des bords fins. Enfin, une première implémentation matérielle est proposée pour évaluer la latence de l'algorithme
A Red, Green, Blue and Depth (RGB-Z) system is a vision system-on-chip (V-SoC) that captures both color and depth information. Recently, the idea of combining color and depth acquisition at the pixel level and in the same array has emerged. Such a sensor would allow a more compact integration while reducing the calibration problems compared to a system composed of two sensors. However, such integration raises new constraints at different technical levels. In this thesis, we focus on the problems of reconstructing the missing color information due to the heterogeneity of the pixel matrix. Currently, there is no monolithic RGB-Z sensor on the market as described in the thesis. In a first step, we have proposed different RGB-Z arrays. These arrays are based on two different Z-pixel architectures. The sampling and the size of the Z pixels vary according to the proposed matrices. In a second step, several algorithms for reconstructing the missing information inspired by the state of the art have been adapted and implemented to the proposed matrices. These solutions are not satisfactory. For this purpose, an adaptive algorithm to reconstruct the missing color information using a new operator called semi-gradient is proposed. This operator allows to better reconstruct the structures located along the narrow edges. Finally, a first hardware implementation is proposed to evaluate the latency of the algorithm

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Nguyen, Duy Thuy. "Développement d'algorithmes de reconstruction tomographique pour l'analyse PIXE d'échantillons biologiques". Phd thesis, Université Sciences et Technologies - Bordeaux I, 2008. http://tel.archives-ouvertes.fr/tel-00404564.

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Le développement des techniques de microscopie 3D offrant une résolution spatiale de l'ordre du micromètre a ouvert un large champ de recherche en biologie cellulaire. Parmi elles, un avantage intéressant de la micro-tomographie par faisceau d'ions est de donner des résultats quantitatifs en termes de concentrations locales d'une manière directe, en utilisant une technique d'émission de rayonnement X (PIXET) combinée à la microscopie ionique en transmission (STIMT). Le traitement des données expérimentales constitue un point délicat. Après une brève introduction aux techniques de reconstruction existantes, nous présentons le principe du code DISRA, le plus complet écrit jusqu'à ce jour, qui nous a servi de base pour ce travail de thèse. Nous avons modifié et étendu le code DISRA en considérant les aspects spécifiques des échantillons biologiques. Un logiciel de traitement de données complet a ainsi été développé, avec une interface utilisateur permettant le contrôle de chaque étape de la reconstruction. Les résultats d'expériences de STIMT et/ou PIXET effectuées au CENBG sur des spécimens de référence et sur des cellules végétales ou humaines isolées sont présentés.

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Casas, Guido Eda Leslie Mónica. "3D reconstruction of chronic wounds using a hand-held camcorder and its application in cutaneous leishmaniasis wounds". Master's thesis, Pontificia Universidad Católica del Perú, 2015. http://tesis.pucp.edu.pe/repositorio/handle/123456789/8135.

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Chronic wounds are a major healthcare problem worldwide which mainly a ects geriatric population and patients with limited mobility. In tropical countries, Cutaneous Leishmaniasis (CL) is also a cause for chronic wounds, being endemic in 75% of Peru . In this context, the assessment of these type of wounds represents a big challenge due to the limited access to specialized medical resources. This work aims to develop a video-based method to compute the 3D point cloud of skin wounds which could provide accurate metrics for medical assessment despite of the location of the patient. Recently, CL specialists have used metrics as volume in clinical assessment with promising results. The acquisition protocol is prompt to be user friendly and feasible in remote locations; the video is taken using a commercial hand-held video camera without a rig or special illumination. The algorithm follows the Structure from Motion methodology: FAST feature detector, pyramidal optical flow and Jacob’s method for missing points estimation. The results show good performance in terms of accuracy and repeatability of the point cloud computation, less than 0.6 mm and 0.21 mm respectively. However, experiments suggest that the volume computation technique does not adapt well to the proposed method output and requires a deeper analysis. The method has been entirely implemented using open source libraries.
Tesis

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Nawaf, Mohamad Motasem. "3D structure estimation from image stream in urban environment". Thesis, Saint-Etienne, 2014. http://www.theses.fr/2014STET4024/document.

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Dans le domaine de la vision par ordinateur, l’estimation de la structure d’une scène 3D à partir d’images 2D constitue un problème fondamental. Parmi les applications concernées par cette problématique, nous nous sommes intéressés dans le cadre de cette thèse à la modélisation d’un environnement urbain. Nous nous sommes intéressés à la reconstruction de scènes 3D à partir d’images monoculaires générées par un véhicule en mouvement. Ici, plusieurs défis se posent à travers les différentes étapes de la chaine de traitement inhérente à la reconstruction 3D. L’un de ces défis vient du fait de l’absence de zones suffisamment texturées dans certaines scènes urbaines, d’où une reconstruction 3D (un nuage de points 3D) trop éparse. De plus, du fait du mouvement du véhicule, d’une image à l’autre il n’y a pas toujours un recouvrement suffisant entre différentes vues consécutives d’une même scène. Dans ce contexte, et ce afin de lever les verrous ci-dessus mentionnés, nous proposons d’estimer, de reconstruire, la structure d’une scène 3D par morceaux en se basant sur une hypothèse de planéité. Nous proposons plusieurs améliorations à la chaine de traitement associée à la reconstruction 3D. D’abord, afin de structurer, de représenter, la scène sous la forme d’entités planes nous proposons une nouvelle méthode de reconstruction 3D, basée sur le regroupement de pixels similaires (superpixel segmentation), qui à travers une représentation multi-échelle pondérée fusionne les informations de couleur et de mouvement. Cette méthode est basée sur l’estimation de la probabilité de discontinuités locales aux frontières des régions calculées à partir du gradient (gradientbased boundary probability estimation). Afin de prendre en compte l’incertitude liée à l’estimation du mouvement, une pondération par morceaux est appliquée à chaque pixel en fonction de cette incertitude. Cette méthode génère des regroupements de pixels (superpixels) non contraints en termes de taille et de forme. Pour certaines applications, telle que la reconstruction 3D à partir d’une séquence d’images, des contraintes de taille sont nécessaires. Nous avons donc proposé une méthode qui intègre à l’algorithme SLIC (Simple Linear Iterative Clustering) l’information de mouvement. L’objectif étant d’obtenir une reconstruction 3D plus dense qui estime mieux la structure de la scène. Pour atteindre cet objectif, nous avons aussi introduit une nouvelle distance qui, en complément de l’information de mouvement et de données images, prend en compte la densité du nuage de points. Afin d’augmenter la densité du nuage de points utilisé pour reconstruire la structure de la scène sous la forme de surfaces planes, nous proposons une nouvelle approche qui mixte plusieurs méthodes d’appariement et une méthode de flot optique dense. Cette méthode est basée sur un système de pondération qui attribue un poids pré-calculé par apprentissage à chaque point reconstruit. L’objectif est de contrôler l’impact de ce système de pondération, autrement dit la qualité de la reconstruction, en fonction de la précision de la méthode d’appariement utilisée. Pour atteindre cet objectif, nous avons appliqué un processus des moindres carrés pondérés aux données reconstruites pondérées par les calculés par apprentissage, qui en complément de la segmentation par morceaux de la séquence d’images, permet une meilleure reconstruction de la structure de la scène sous la forme de surfaces planes. Nous avons également proposé un processus de gestion des discontinuités locales aux frontières de régions voisines dues à des occlusions (occlusion boundaries) qui favorise la coplanarité et la connectivité des régions connexes. L’ensemble des modèles proposés permet de générer une reconstruction 3D dense représentative à la réalité de la scène. La pertinence des modèles proposés a été étudiée et comparée à l’état de l’art. Plusieurs expérimentations ont été réalisées afin de démontrer, d’étayer, la validité de notre approche
In computer vision, the 3D structure estimation from 2D images remains a fundamental problem. One of the emergent applications is 3D urban modelling and mapping. Here, we are interested in street-level monocular 3D reconstruction from mobile vehicle. In this particular case, several challenges arise at different stages of the 3D reconstruction pipeline. Mainly, lacking textured areas in urban scenes produces low density reconstructed point cloud. Also, the continuous motion of the vehicle prevents having redundant views of the scene with short feature points lifetime. In this context, we adopt the piecewise planar 3D reconstruction where the planarity assumption overcomes the aforementioned challenges.In this thesis, we introduce several improvements to the 3D structure estimation pipeline. In particular, the planar piecewise scene representation and modelling. First, we propose a novel approach that aims at creating 3D geometry respecting superpixel segmentation, which is a gradient-based boundary probability estimation by fusing colour and flow information using weighted multi-layered model. A pixel-wise weighting is used in the fusion process which takes into account the uncertainty of the computed flow. This method produces non-constrained superpixels in terms of size and shape. For the applications that imply a constrained size superpixels, such as 3D reconstruction from an image sequence, we develop a flow based SLIC method to produce superpixels that are adapted to reconstructed points density for better planar structure fitting. This is achieved by the mean of new distance measure that takes into account an input density map, in addition to the flow and spatial information. To increase the density of the reconstructed point cloud used to performthe planar structure fitting, we propose a new approach that uses several matching methods and dense optical flow. A weighting scheme assigns a learned weight to each reconstructed point to control its impact to fitting the structure relative to the accuracy of the used matching method. Then, a weighted total least square model uses the reconstructed points and learned weights to fit a planar structure with the help of superpixel segmentation of the input image sequence. Moreover, themodel handles the occlusion boundaries between neighbouring scene patches to encourage connectivity and co-planarity to produce more realistic models. The final output is a complete dense visually appealing 3Dmodels. The validity of the proposed approaches has been substantiated by comprehensive experiments and comparisons with state-of-the-art methods

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Más fuentes

Libros sobre el tema "Reconstruction de pixel"

Jähne, Bernd. Digital image processing: Concepts, algorithms, and scientific applications. Berlin: Springer-Verlag, 1991.

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Digital image processing. 6^a ed. Berlin: Springer, 2005.

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Digital image processing: Concepts, algorithms, and scientific applications. 4^a ed. Berlin: Springer, 1997.

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Jähne, Bernd. Digital image processing: Concepts, algorithms, and scientific applications. 3^a ed. Berlin: Springer-Verlag, 1995.

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Jähne, Bernd. Digital image processing: Concepts, algorithms, and scientific applications. 2^a ed. Berlin: Springer-Verlag, 1993.

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Capítulos de libros sobre el tema "Reconstruction de pixel"

Green, A. R., F. Lei, A. J. Bird, I. D. Jupp y A. J. Dean. "Incident Pixel Reconstruction for Gamma Ray Telescopes". En Imaging in High Energy Astronomy, 235–38. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-011-0407-4_34.

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Yaguchi, Yuichi, Kenta Iseki, Nguyen Tien Viet y Ryuichi Oka. "3D Object Reconstruction Using Full Pixel Matching". En Computer Analysis of Images and Patterns, 873–80. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-03767-2_106.

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Burger, Martin, Janic Föcke, Lukas Nickel, Peter Jung y Sven Augustin. "Reconstruction Methods in THz Single-Pixel Imaging". En Applied and Numerical Harmonic Analysis, 263–90. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-319-73074-5_9.

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Rodríguez, Marc, Gaëlle Largeteau-Skapin y Eric Andres. "Adaptive Pixel Resizing for Multiscale Recognition and Reconstruction". En Lecture Notes in Computer Science, 252–65. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-10210-3_20.

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Vami, Tamas Almos y Viktor Veszpremi. "Study of the CMS Phase 1 Pixel Pilot Blade Reconstruction". En Springer Proceedings in Physics, 366–69. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-13-1316-5_68.

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Schneider, Christian, Maximilian Meyer y Tim Kunz. "Automotive 3D reconstruction based on multi-pixel LED headlight systems". En Proceedings, 85–112. Wiesbaden: Springer Fachmedien Wiesbaden, 2017. http://dx.doi.org/10.1007/978-3-658-19059-0_6.

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Huang, Hong, Xingyang Li y Wenjian He. "Pixel-Wise Reconstruction of Private Data in Split Federated Learning". En Information and Communications Security, 435–50. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-7356-9_26.

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Chan, Kennard Yanting, Guosheng Lin, Haiyu Zhao y Weisi Lin. "IntegratedPIFu: Integrated Pixel Aligned Implicit Function for Single-View Human Reconstruction". En Lecture Notes in Computer Science, 328–44. Cham: Springer Nature Switzerland, 2022. http://dx.doi.org/10.1007/978-3-031-20086-1_19.

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Huang, Linjie, Zhe Zhang, Shaohua Wu y Junjun Xiao. "Improved Video Reconstruction Basing on Single-Pixel Camera By Dual-Fiber Collecting". En Lecture Notes in Electrical Engineering, 90–97. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-6504-1_12.

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Dolveck-Guilpart, B. "Tomographic Image Reconstruction from a Limited Set of Projections Using a Natural Pixel Decomposition". En Inverse Problems and Theoretical Imaging, 54–61. Berlin, Heidelberg: Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-75298-8_7.

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Actas de conferencias sobre el tema "Reconstruction de pixel"

Childers, Taylor, Matti Kortelainen, Martin Kwok, Alexei Strelchenko y Yunsong Wang. "Porting CMS Heterogeneous Pixel Reconstruction to Kokkos". En Porting CMS Heterogeneous Pixel Reconstruction to Kokkos. US DOE, 2021. http://dx.doi.org/10.2172/1827400.

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Gabaldon, Charris, Savannah L. Cuozzo, Pratik J. Barge, Ziqi Niu, Hwang Lee, Lior Cohen, Irina Novikova y Eugeniy E. Mikhailov. "Single-pixel Imaging with Full Wavefront Reconstruction via Homodyne Detection". En Frontiers in Optics. Washington, D.C.: Optica Publishing Group, 2022. http://dx.doi.org/10.1364/fio.2022.jw5a.71.

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We demonstrate the spatial transmission (amplitude and phase) map reconstructions of semi-transparent objects without a camera by recording interference traces of transmitted probe beams and structured references. No prior object information is needed for reconstruction.

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Andriotis, N., A. Bocci, E. Cano, L. Cappelli, M. Dewing, T. Di Pilato, J. Esseiva et al. "Evaluating Performance Portability with the CMS Heterogeneous Pixel Reconstruction code". En Evaluating Performance Portability with the CMS Heterogeneous Pixel Reconstruction code. US DOE, 2023. http://dx.doi.org/10.2172/1973419.

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Kwok, Martin y Matti Kortelainen. "Performance of CUDA Unified Memory in CMS Heterogeneous Pixel Reconstruction". En Performance of CUDA Unified Memory in CMS Heterogeneous Pixel Reconstruction. US DOE, 2021. http://dx.doi.org/10.2172/1827369.

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Frieden, B. Roy y Hartmut H. G. Aumann. "Image reconstruction from a staggered array using filtered localized projection". En OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1986. http://dx.doi.org/10.1364/oam.1986.mr5.

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It is common nowadays to collect image data by scanning the image field with a staggered array of solid state detectors. This may also be from several directions. In view of the finite size of each detector, the reconstructed image is limited in resolution or pixel size. How small may this be made? An efficient way of combining the scan data is localized projection. By this method, the required pixel size is first fixed. Then, the intensity within each pixel area is incremented by the readings from all scanning detectors that spatially intercept it, regardless of the detector size, its direction of scan, etc. This locally projected image will have a characteristic point spread function which may spill out over a few pixels. To reduce this spillage (perhaps to one pixel) a simple filtering operation to accomplish partial deconvolution may be performed. This filtered-locally projected approach has so far been applied to simulated IRAS astronomical data where all the scans are parallel. The effects of noise and dead detectors have also been investigated with encouraging results.

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Fursich, Benjamin, Richard Bamler, Sven Augustin, Heinz-Wilhelm Hubers y Xiao Xiang Zhu. "Towards single-pixel FMCW radar reconstruction". En 2016 4th International Workshop on Compressed Sensing Theory and its Applications to Radar, Sonar and Remote Sensing (CoSeRa). IEEE, 2016. http://dx.doi.org/10.1109/cosera.2016.7745707.

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Patra, S. K., J. Saibaba, Geeta Varadan y S. K. Nayak. "A technique for spectral pixel reconstruction". En IGARSS 2011 - 2011 IEEE International Geoscience and Remote Sensing Symposium. IEEE, 2011. http://dx.doi.org/10.1109/igarss.2011.6049795.

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Ju, Yakun, Kin-Man Lam, Yang Chen, Lin Qi y Junyu Dong. "Pay Attention to Devils: A Photometric Stereo Network for Better Details". En Twenty-Ninth International Joint Conference on Artificial Intelligence and Seventeenth Pacific Rim International Conference on Artificial Intelligence {IJCAI-PRICAI-20}. California: International Joint Conferences on Artificial Intelligence Organization, 2020. http://dx.doi.org/10.24963/ijcai.2020/97.

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We present an attention-weighted loss in a photometric stereo neural network to improve 3D surface recovery accuracy in complex-structured areas, such as edges and crinkles, where existing learning-based methods often failed. Instead of using a uniform penalty for all pixels, our method employs the attention-weighted loss learned in a self-supervise manner for each pixel, avoiding blurry reconstruction result in such difficult regions. The network first estimates a surface normal map and an adaptive attention map, and then the latter is used to calculate a pixel-wise attention-weighted loss that focuses on complex regions. In these regions, the attention-weighted loss applies higher weights of the detail-preserving gradient loss to produce clear surface reconstructions. Experiments on real datasets show that our approach significantly outperforms traditional photometric stereo algorithms and state-of-the-art learning-based methods.

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Higashida, Ryo, Mayumi Kawana, Ken-ichi Aoshima y Nobuhiko Funabashi. "Holographic Display Using Magneto-optical Spatial Light Modulator with 50-M pixels and 1-μm pixel pitch". En 3D Image Acquisition and Display: Technology, Perception and Applications. Washington, D.C.: Optica Publishing Group, 2023. http://dx.doi.org/10.1364/3d.2023.jtu4a.47.

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We clarified a bias magnetic field can correct the asymmetric magnetization switching properties of a fabricated magneto-optical spatial light modulator with 50-M pixels and 1-μm pixel pitch. Additionally, the successful holographic images reconstruction was demonstrated.

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Zhang, Liangpei, Xiong Xu, Jie Li, Huanfeng Shen, Yanfei Zhong y Xin Huang. "Research on image reconstruction based and pixel unmixing based sub-pixel mapping methods". En IGARSS 2012 - 2012 IEEE International Geoscience and Remote Sensing Symposium. IEEE, 2012. http://dx.doi.org/10.1109/igarss.2012.6351985.

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