The article presents a comparison of two statistical approaches to the problem of imagereconstructionfrom projections: the worldwide known concept based on a discrete-to-discrete data model and our original idea bas...
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ISBN:
(纸本)9783031087547;9783031087530
The article presents a comparison of two statistical approaches to the problem of imagereconstructionfrom projections: the worldwide known concept based on a discrete-to-discrete data model and our original idea based on a continuous-to-continuous data model. Both reconstruction approaches are formulated taking into account the statistical properties of signals obtained by CT scanners. The main goal of this strategy is significantly improving the quality of the reconstructed images, so allowing a reduction in the x-ray dose absorbed by a patient during CT examinations. In the concept proposed by us, the reconstruction problem is formulated as a shift-invariant system. In consequence, that significantly improves the quality of the subsequently reconstructed images, and it allows to reduce the computational complexity compared to the reference method. The performed by us experiments have shown that our original reconstruction method outperforms the referential approach regarding the image quality obtained and the time of necessary calculations.
We present Viewset Diffusion, a diffusion-based generator that outputs 3D objects while only using multi-view 2D data for supervision. We note that there exists a one-to-one mapping between viewsets, i.e., collections...
ISBN:
(纸本)9798350307184
We present Viewset Diffusion, a diffusion-based generator that outputs 3D objects while only using multi-view 2D data for supervision. We note that there exists a one-to-one mapping between viewsets, i.e., collections of several 2D views of an object, and 3D models. Hence, we train a diffusion model to generate viewsets, but design the neural network generator to reconstruct internally corresponding 3D models, thus generating those too. We fit a diffusion model to a large number of viewsets for a given category of objects. The resulting generator can be conditioned on zero, one or more input views. Conditioned on a single view, it performs 3D reconstruction accounting for the ambiguity of the task and allowing to sample multiple solutions compatible with the input. The model performs reconstruction efficiently, in a feed-forward manner, and is trained using only rendering losses using as few as three views per viewset. Project page: ***/viewset-diffusion.
In this paper, automated planogram compliance technique is proposed for retail applications. A mobile robot with camera vision capabilities provides the images of the products on shelves, which are processed to recons...
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ISBN:
(数字)9783031590573
ISBN:
(纸本)9783031590566;9783031590573
In this paper, automated planogram compliance technique is proposed for retail applications. A mobile robot with camera vision capabilities provides the images of the products on shelves, which are processed to reconstruct an overall image of the shelves to be compared to the planogram. The imagereconstruction includes image frames extraction from live video stream, images stitching and concatenation. Object detection, for the products, is achieved using a deep learning tool based on YOLOv5 model. dataset, for algorithm training and testing, is built to identify the products based on their image identification, number, and location on the shelf. A small scale of shelves with products is built and different cases of products on shelves are tested in a laboratory environment. It was found that YOLOv5 algorithm detects various products on shelves with a precision of 0.98, recall of 0.99, F-measure of 0.98, and clarification loss of 0.006.
Traditional low-rank methods overlook residuals as corruptions, but we discovered that low-rank residuals actually keep image edges together with corrupt components. Therefore, filtering out such structural informatio...
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ISBN:
(纸本)9781577358800
Traditional low-rank methods overlook residuals as corruptions, but we discovered that low-rank residuals actually keep image edges together with corrupt components. Therefore, filtering out such structural information could hamper the discriminative details in images, especially in heavy corruptions. In order to address this limitation, this paper proposes a novel method named ESL-LRR, which preserves image edges by finding image projections from low-rank residuals. Specifically, our approach is built in a manifold learning framework where residuals are regarded as another view of imagedata. Edge preserved image projections are then pursued using a dynamic affinity graph regularization to capture the more accurate similarity between residuals while suppressing the influence of corrupt ones. With this adaptive approach, the proposed method can also find image intrinsic low-rank representation, and much discriminative edge preserved projections. As a result, a new classification strategy is introduced, aligning both modalities to enhance accuracy. Experiments are conducted on several benchmark imagedatasets, including MNIST, LFW, and COIL100. The results show that the proposed method has clear advantages over compared state-of-the-art (SOTA) methods, such as Low-Rank Embedding (LRE), Low-Rank Preserving Projection via Graph Regularized reconstruction (LRPP GRR), and Feature Selective Projection (FSP) with more than 2% improvement, particularly in corrupted cases.
Recent advances in generative adversarial networks (GANs) have opened up the possibility of generating high-resolution photo-realistic images that were impossible to produce previously. The ability of GANs to sample f...
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ISBN:
(纸本)9781665405409
Recent advances in generative adversarial networks (GANs) have opened up the possibility of generating high-resolution photo-realistic images that were impossible to produce previously. The ability of GANs to sample from high-dimensional distributions has naturally motivated researchers to leverage their power for modeling the image prior in inverse problems. We extend this line of research by developing a Bayesian imagereconstruction framework that utilizes the full potential of a pre-trained StyleGAN2 generator, which is the currently dominant GAN architecture, for constructing the prior distribution on the underlying image. Our proposed approach, which we refer to as learned Bayesian reconstruction with generative models (L-BRGM), entails joint optimization over the style-code and the input latent code, and enhances the expressive power of a pre-trained StyleGAN2 generator by allowing the style-codes to be different for different generator layers. Considering the inverse problems of image inpainting and super-resolution, we demonstrate that the proposed approach is competitive with, and sometimes superior to, state-of-the-art GAN-based imagereconstruction methods.
In this study, we show how S&P 500 Index volatility surfaces can be modeled in a purely data-driven way using variational autoencoders. The approach autonomously learns concepts such as the volatility level, smile...
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ISBN:
(数字)9783031236334
ISBN:
(纸本)9783031236327;9783031236334
In this study, we show how S&P 500 Index volatility surfaces can be modeled in a purely data-driven way using variational autoencoders. The approach autonomously learns concepts such as the volatility level, smile, and term structure without leaning on hypotheses from traditional volatility modeling techniques. In addition to introducing notable improvements to an existing variational autoencoder approach for the reconstruction of both complete and incomplete volatility surfaces, we showcase three practical use cases to highlight the relevance of this approach to the financial industry. First, we show how the latent space learned by the variational autoencoder can be used to produce synthetic yet realistic volatility surfaces. Second, we demonstrate how entire sequences of synthetic volatility surfaces can be generated to stress test and analyze an options portfolio. Third and last, we detect anomalous surfaces in our options dataset and pinpoint exactly which subareas are divergent.
Diffuse optical tomography (DOT) is a non-invasive, label-free imaging technique widely used in applications such as breast cancer diagnosis and brain imaging. It allows for the quantitative measurement of tissue func...
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This study examines the pressure drops and flow patterns in a Chevron-type Compact Plate Heat Exchanger (CPHE) with air-water two-phase mixture under adiabatic conditions. A transparent replica channel, made from epox...
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This study examines the pressure drops and flow patterns in a Chevron-type Compact Plate Heat Exchanger (CPHE) with air-water two-phase mixture under adiabatic conditions. A transparent replica channel, made from epoxy resin, was used to mimic the heat exchanger's fluid dynamics and allow for optical access. The channel featured a 63 degrees corrugation angle, 2.5 mm depth, and 8.9 mm pitch, yielding a global enlargement factor of 1.17. A particular inlet section was designed to ensure even phase mixing and distribution. Operating conditions varied from 6 to 365 kg/m(2)s for water and 0.02 to 5 kg/m(2)s for air, expanding the range of previous studies. High-framerate back-illuminated visualizations provided detailed observations of the flow patterns. Moreover, frame-by-frame void fraction was estimated via HSV video analysis adopting a convolutional neural network (U-Net) to produce binary masks and estimate gas bubble volumes and via a volume-reconstruction algorithm exploiting the pseudo-2D shape of the channel. A novel correlation for Darcy's friction factor based on Reynolds number was developed for single-phase flow, complemented by an analysis of two-phase pressure drops using a two-phase multiplier correlated with the Lockhart-Martinelli parameter. The incorporation of void fraction data significantly improved their modelling accuracy.
In radio astronomy, signals from radio telescopes are transformed into images of observed celestial objects, or sources. However, these images, called dirty images, contain real sources as well as artifacts due to sig...
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This research project explores a paradigm shift in perceptual enhancement by integrating a Unified Recognition Framework and Vision-Language Pre-Training in three-dimensional imagereconstruction. Through the synergy ...
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