- 标题
- 摘要
- 关键词
- 实验方案
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Comparison of four iterative methods for improving the contrast of the radiography images
摘要： Recently, radiography image elaboration using different image processing methods has been introduced as an alternative to enhance the radiographs. The ability of improving the quality of an image depends on the scattered X-ray and the acquisition data by electronic system in digital radiography (RT). Iterative methods, well known in general sparse signal reconstruction, can be suited for the radiography images. In this research, the digital radiography image is improved by minimizing an objective function using the Fast Iterative Shrinkage-Thresholding Algorithm (FISTA), Monotone FISTA (MFISTA), Over relaxation MFISTA (OMFISTA) and Converged FISTA (CFISTA), where the solution sparsity may be adjusted as desired. The paper surveys four well-known methods for sparse process, and assesses their optimization parameters with the goal of obtaining the best algorithm for industrial radiography images. First, the radiographs from the welded objects were provided and four iterative methods were implemented to the radiographs for enhancing the contrast. Then reconstructed images were assessed on the basis of their quality. The results show that the reconstructed images have better contrast than the original radiography and the OMFISTA method has a lower runtime compared to others. Also, the results demonstrate the viability and efficiency of the four proposed algorithms on radiography image deblurring problems without any information about the noise of radiography system.
关键词： Image Reconstruction,Welded Objects,Radiography Image,Iterative Methods
更新于2025-09-10 09:29:36
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Impact of a novel exponential weighted 4DCT reconstruction?algorithm
摘要： Purpose: This work characterizes a novel exponential 4DCT reconstruction algorithm (EXPO), impact on image quality as compared to the standard cosine‐squared weighted 4DCT in phantom and patient, to determine its reconstruction. Methods: A motion platform translated objects in the superior–inferior (S‐I) direction at varied breathing rates (8–20 bpm) and couch pitches (0.06–0.1) to evaluate interplay between parameters. Ten‐phase 4DCTs were acquired and data were reconstructed with cosine squared and EXPO weighting. To quantify the magnitude of image blur, objects were translated in the anterior–posterior (A‐P) and S‐I directions for full‐width half maximum (FWHM) analysis between both 4DCT algorithms and a static case. 4DCT sinogram data for 10 patients were retrospectively reconstructed using both weighting factors. Image subtractions elucidated intensity and boundary differences. Subjective image quality grading (presence of image artifacts, noise, spatial resolution (i.e., lung/liver boundary sharpness), and overall image quality) was conducted yielding 200 evaluations. Results: After taking static object size into account, the FWHM of EXPO reconstructions in the A‐P direction was 3.3 ± 1.7 mm (range: 0–4.9) as compared to cosine squared 9.8 ± 4.0 mm (range: 2.6–14.4). The FWHM of objects translated in the S‐I direction reconstructed with EXPO agreed better with the static FWHM than the cosine‐squared reconstructions. Slower breathing periods, faster couch pitches, and intermediate 4DCT phases had the largest reductions of blurring with EXPO. 18 of 60 comparisons of artifacts were improved with EXPO reconstruction, whereas no appreciable changes were observed in image quality scores. In 18 of 20 cases, EXPO provided sharper images although the reduced projections also increased baseline noise. Conclusion: Exponential weighted 4DCT offers potential for reducing image blur (i.e., improving image sharpness) in 4DCT with a tendency to reduce artifacts. Future work will involve evaluating the impact on treatment planning including delineation ability and dose calculation.
关键词： reconstruction,artifacts,4DCT
更新于2025-09-10 09:29:36
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Reconstruction of 3D Forest Mock-Ups from Airborne LiDAR Data for Multispectral Image Simulation Using DART Model
摘要： Three dimensional(3D) radiative transfer simulation is becoming an important and essential tool to understand the interaction between solar radiation and forestcanopies. However, conducting a 3D simulation usually needsa lot of input parameters, especially the 3D informationof forest scene, which is difficult to obtain and reconstruct. This paper presents a voxel approach that derives forest mock-upsfrom LiDAR data. These 3D mock-ups are adapted to DART model, using its recently introduced data access objects (DAO) tool. Here, they are used to simulate multispectral imageswith DART.
关键词： image simulation,LiDAR,forest,3D reconstruction
更新于2025-09-10 09:29:36
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Robust Super-Resolution Image Reconstruction Method for Geometrically Deformed Remote Sensing Images
摘要： Due to the limitations of imaging sensors, remote sensing images often have limited resolution. To address this issue, various super-resolution (SR) image reconstruction techniques have been developed to reconstruct a high-resolution image from a sequence of low-resolution, noisy and blurry observations. In this paper, we propose an efficient super-resolution image reconstruction method for geometrically deformed remote sensing images, based on the nonlocal total variation (NLTV) regularization. The proposed minimization problem is solved by a fast primal-dual algorithm. Numerical experiments demonstrate the performance of the proposed method.
关键词： super-resolution image reconstruction,Remote sensing images,primal-dual algorithm
更新于2025-09-10 09:29:36
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Salient Object Detection Via Double Sparse Representations Under Visual Attention Guidance
摘要： This paper introduces a novel method for salient object detection from the perspective of sparse representation under visual attention guidance. After pretreatment and regional analysis with eye fixation detection and multi scale segmentation, regions that are used to make up the foreground and background dictionaries are respectively selected by sorting the visual attraction level of all image regions. For saliency measurement, the reconstruction errors instead of common local and global contrasts are used as the saliency indicator, which is expected to improve the object integrity. In addition, the multi scale workflow is conductive to enhance the robustness for objects of different sizes. The proposed method was compared to six state-of-the-art saliency detection methods using three benchmark datasets, and it was confirmed to have more favorable performance in the detection of multiple objects as well as maintaining the integrity of the object area.
关键词： Salient object detection,visual attention guidance,reconstruction error,sparse representation
更新于2025-09-10 09:29:36
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[IEEE 2018 37th Chinese Control Conference (CCC) - Wuhan (2018.7.25-2018.7.27)] 2018 37th Chinese Control Conference (CCC) - Pipeline Scene Reconstruction Based on Image Mosaicing
摘要： Robots should be able to perceive the surroundings in the complicated and unknown environment before carrying out further navigation. Consequently, environmental reconstruction is the premise for the robot autonomous operations. In this paper, a pipeline scene reconstruction method based on image mosaicing is proposed for cylindrical pipeline environment. With a wide-angle camera, the image sequence of the pipeline environment is captured. In order to obtain intuitional environmental information around the pipeline, an unwrapped model is proposed to unfold the distorted raw image to corrected ?at surface image. By utilizing ORB (Oriented FAST and Rotated BRIEF) and weighted smoothing blending algorithm, image mosaicing with sequence frames are performed to realize scene reconstruction. The experimental results demonstrate that the proposed algorithm can achieve seamless stitching of pipeline image, and the number of keypoints is prominently decreased in comparison to that of FAST operator, while the quality of keypoints is improved. Compared with the classical SIFT and SURF operator, the time-consuming of the algorithm is improved about 2.5 times, which is more suitable for real-time environmental reconstruction.
关键词： image mosaicing,ORB,scene reconstruction,image unwrapping
更新于2025-09-10 09:29:36
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Reconstruction and analysis of exploding wire particle trajectories via automatic calibration of stereo images
摘要： Quantitative understanding of the physics of dust or granular matter transport significantly impacts several aspects of burning plasma science and technology. This work takes machine vision techniques popular in robotics and self-driving cars and applies them to identification and analysis of microparticles generated from exploding wires. Using only the image frames and knowledge of the intrinsic properties of the cameras, a Python code was written to identify the particles, automatically calibrate the relative image positions, and extract trajectory data. After identifying approximately 50 particles based on the timing of secondary particle explosions, the eight point and random sample consensus algorithms were used to determine the geometric correlation between the cameras. Over 100 particle matches were found between the two camera views. These correlated trajectories were used in subsequent 3D track reconstruction and analysis of the physics behind the particle motion. The 3D reconstruction resulted in accurate positioning of the particles with respect to the experimental setup. The particle motion was consistent with the effects of a 1 g gravitational field modified by drag forces. The methods and analyses presented here can be used in many facets of high temperature plasma diagnostics.
关键词： stereo images,automatic calibration,plasma diagnostics,particle trajectories,3D reconstruction,exploding wire
更新于2025-09-10 09:29:36
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Cloud Photogrammetry with Dense Stereo for Fisheye Cameras
摘要： In this paper, we present our approach for dense 3D cloud reconstruction using two hemispheric sky imagers with fisheye lenses in a stereo setup. Fisheye lenses follow a different projection function than classical pinhole-type cameras, which provide a large field of view with a single image, but also renders the computation of dense 3D information more complicated, such that we cannot rely entirely on standard implementations for dense 3D stereo reconstruction. In this work, we examine the epipolar rectification model, which allows the use of dense matching algorithms designed for classical perspective cameras to search for disparity information at every pixel. Together with an appropriate camera calibration, which includes internal camera geometry and global position and orientation of the stereo camera pair, we can use the disparity information for dense 3D stereo reconstruction of the a cloud and thus estimate its shape. From the obtained 3D shapes, cloud dynamics, size, motion, type and spacing can be derived and used e.g. for radiation closure under cloudy conditions. We implemented and evaluated the proposed approach using real world data and present two case studies. In the first case, we validate the quality and accuracy of the method by comparing the stereo reconstruction of a stratocumulus layer with the reflectivity observations measured by a cloud radar and the cloud base height estimated from a Lidar-ceilometer. The second case analyzes a rapid cumulus convection in the presence of strong wind shear.
关键词： fisheye cameras,cloud photogrammetry,dense stereo,cloud dynamics,3D reconstruction
更新于2025-09-10 09:29:36
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Repeatability of <sup>18</sup> F-FDG PET Radiomic Features: a Phantom Study to Explore Sensitivity to Image Reconstruction Settings, Noise, and Delineation Method
摘要： Background: 18F-fluoro-2-deoxy-D-Glucose positron emission tomography (18F-FDG PET) radiomics has the potential to guide the clinical decision making in cancer patients, but validation is required before radiomics can be implemented in the clinical setting. The aim of this study was to explore how feature space reduction and repeatability of 18F-FDG PET radiomic features are affected by various sources of variation such as underlying data (e.g. object size and uptake), image reconstruction methods and settings, noise, discretization method, and delineation method.
关键词： 18F-FDG PET/CT radiomic features,delineation,image reconstruction settings
更新于2025-09-10 09:29:36
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Sensor resolution enhancement for remote imaging by synthesizing mask-based camera array images
摘要： In this paper, we propose an architecture based on camera array with masks to enhance the sensor resolution of remote imaging system. The sensor resolution is enhanced by multiplexing the sensor images of each camera, in which the angular resolution bandwidth is converted using masks to expand the spatial resolution bandwidth. The improvement of the sensor resolution depends on the number of cameras in the array. The theory of improving the sensor resolution is discussed both in Fourier domain and spatial domain. We verify resolution enhancement of the architecture by ray-tracing imaging simulation. A simulation model is built to verify the resolution-enhancing ability of the camera array architecture. From each camera in the array, we get a resolution-limited image. The reconstructed image is synthesized from all the images of the cameras. The post-synthesized image has finer information details compared with the images of each camera. The resolution improvement varies with the object distance. The optimal resolution improvement of the reconstructed image is equal to the total sensor pixels of the camera array.
关键词： Image reconstruction,Light field,Remote imaging,Resolution enhancement
更新于2025-09-10 09:29:36