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A statistical learning method for image-based monitoring of the plume signature in laser powder bed fusion
摘要： The industrial breakthrough of metal additive manufacturing processes mainly involves highly regulated sectors, e.g., aerospace and healthcare, where both part and process qualification are of paramount importance. Because of this, there is an increasing interest for in-situ monitoring tools able to detect process defects and unstable states since their onset stage during the process itself. In-situ measured quantities can be regarded as “signatures” of the process behaviour and proxies of the final part quality. This study relies on the idea that the by-products of laser powder bed fusion (LPBF) can be used as process signatures to design and implement statistical monitoring methods. In particular, this paper proposes a methodology to monitor the LPBF process via in-situ infrared (IR) video imaging of the plume formed by material evaporation and heating of the surrounding gas. The aspect of the plume naturally changes from one frame to another following the natural dynamics of the process: this yields a multimodal pattern of the plume descriptors that limits the effectiveness of traditional statistical monitoring techniques. To cope with this, a nonparametric control charting scheme is proposed, called K-chart, which allows adapting the alarm threshold to the dynamically varying patterns of the monitored data. A real case study in LPBF of zinc powder is presented to demonstrate the capability of detecting the onset of unstable conditions in the presence of a material that, despite being particularly interesting for biomedical applications, imposes quality challenges in LPBF because of its low melting and boiling points. A comparison analysis is presented to highlight the benefits provided by the proposed approach against competitor methods.
关键词： Process plume,Metal additive manufacturing,Laser powder bed fusion,Infrared imaging,In-situ monitoring,Zinc
更新于2025-11-28 14:24:20
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Spatiotemporal Adaptive Nonuniformity Correction Based on BTV Regularization
摘要： The residual nonuniformity response, ghosting artifacts, and over-smooth effects are the main defects of the existing nonuniformity correction (NUC) methods. In this paper, a spatiotemporal feature-based adaptive NUC algorithm with bilateral total variation (BTV) regularization is presented. The primary contributions of the innovative method are embodied in the following aspects: BTV regularizer is introduced to eliminate the nonuniformity response and suppress the ghosting effects. The spatiotemporal adaptive learning rate is presented to further accelerate convergence, remove ghosting artifacts, and avoid over-smooth. Moreover, the random projection-based bilateral filter is proposed to estimate the desired target image more accurately which yields more details in the actual scene. The experimental results validated that the proposed algorithm achieves outstanding performance upon both simulated data and real-world sequence.
关键词： infrared image sensors,Infrared imaging,neural networks,image denoising
更新于2025-09-23 15:23:52
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Local spatial correlation-based stripe non-uniformity correction algorithm for single infrared images
摘要： Stripe non-uniformity typically exists in infrared images and affects the visual effect; thus, eliminating stripe non-uniformity is essential to improve image quality. In this paper, a correction model with higher accuracy is developed. Unlike some other stripe non-uniformity correction methods using the same gain coefficient and offset parameters for the pixels of each column, different deviations of the correction parameters in the same column resulted by unsatisfactory preliminary non-uniformity correction are considered and are thought to be small and still relevant in space. The proposed method calculates the correction parameters for each pixel respectively based on the intrinsic spatial correlation between adjacent pixels in a column. What is more, an edge detection method is included. The experimental results indicate that the proposed algorithm effectively eliminates stripe noise of images of different scenes and it also works well in terms of preserving details. Furthermore, the algorithm exhibits high real-time performance.
关键词： De-striping,Spatial correlation,Non-uniformity correction,Stripe noise,Infrared imaging
更新于2025-09-23 15:23:52
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Nonuniformity Correction for Variable-Integration-Time Infrared Camera
摘要： A two-dimensional calibration technique is proposed to correct the spatial nonuniformity in infrared imaging systems adapting to different integration time and time-varying offset with one-time calibration. Differing from traditional calibration-based nonuniformity correction, this method calibrates nonuniformity with two-dimensional information from two integration time besides different irradiance, which conquers drawbacks of traditional calibration-based correction. First, it eliminates the dependence on integration time in calibration process and dramatically suppresses fixed pattern noise by a large attenuation factor. In addition, time-varying offset is real-time canceled by the subtraction of images integrated with normal and short time. Correction error of two-point correction and the proposed method are analyzed in detail. In experiments with cooled infrared camera, the proposed method provides enhanced uniformity even for seven-time variation of integration time using same correction coefficients. Both quantitative and qualitative comparisons to two-point correction demonstrate its superiority. The one-time calibration and shutterless correction scheme avoids interruption of the normal operation for real scene, extending the application range in practical engineering for infrared imaging systems with low complexity of computation and hardware.
关键词： Infrared imaging,nonuniformity correction
更新于2025-09-23 15:22:29
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Infrared super-resolution imaging using multi-scale saliency and deep wavelet residuals
摘要： Infrared (IR) imaging systems with low-density focal plane arrays produce images with poor spatial resolution. To address this limitation, super-resolution (SR) algorithms can be applied on IR-low resolution (LR) images. In this paper, we present a new SR technique based on the multi-scale saliency detection and the residuals learned by the deep convolutional neural network (CNN) in the wavelet domain (DWCNN). The input LR image is processed in the transformed domain by applying 2D discrete wavelet transform. It decomposes an image into its low-frequency and high-frequency subbands. The multi-scale saliency detection is used to extract small scale and large scale salient feature maps from the bicubic upscaled LR image. These maps are incorporated in the high-frequency subbands of the LR image. Furthermore, the low-frequency and high-frequency subands are re?ned using the residuals learned by the DWCNN in training phase. The proposed algorithm is compared with the conventional and state-of-the-art SR methods. Results indicate that our method yields good reconstruction quality with high peak signal to ratio, structural similarity and low blur indices. Besides, our method requires less computational time.
关键词： Infrared imaging,Convolutional neural network,Discrete wavelet transform,Multi-scale saliency,Super-resolution
更新于2025-09-23 15:22:29
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Stability Monitoring of the VIIRS Day/Night Band over Dome C with a Lunar Irradiance Model and BRDF Correction
摘要： The unique feature of the Visible Infrared Imager Radiometer Suite (VIIRS) day/night band (DNB) is its ability to take quantitative measurements of low-light scenes at night. In order to monitor the stability of the high gain stage (HGS) of the DNB, nighttime observations over the Dome C site under moonlight are analyzed in this study. The Miller and Turner 2009 (MT2009) lunar irradiance model has been used to simulate lunar illumination over Dome C. However, the MT2009 model does not differentiate the waxing and waning lunar phases. In this paper, the MT-SWC (SeaWiFS Corrected) lunar irradiance model differentiating the waxing and waning lunar phases is derived by correcting the MT2009 model using lunar observations made by the Sea-Viewing Wide Field-of-View Sensor (SeaWiFS). In addition, a top of atmosphere (TOA) bi-directional reflectance distribution function (BRDF) model during nighttime over Dome C is developed to remove the angular dependence from the nighttime TOA reflectance. The long-term stability monitoring of the DNB high-gain stage (HGS) reveals a lower reflectance factor in 2012 in comparison to the following years, which can be traced back to the change in relative spectral response (RSR) of National Oceanic & Atmospheric Administration's (NOAA's) Interface Data Processing Segment (IDPS) VIIRS DNB in April 2013. It also shows the radiometric stability of DNB data, with long-term stability of less than 1.58% over the periods from 2013 to 2016. This method can be used to monitor the radiometric stability of other low-light observing sensors using vicarious calibration sites under moonlight illumination.
关键词： visible infrared imaging radiometer suite (VIIRS),Miller and Turner 2009 (MT2009),Sea-Viewing Wide Field-of-View Sensor (SeaWiFS),Dome C site,day/night band (DNB),lunar observations,BRDF effect
更新于2025-09-23 15:22:29
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A New Generation of NIR-II Probes: Lanthanide-Based Nanocrystals for Bioimaging and Biosensing
摘要： Fluorescence-based imaging in the second near infrared window (NIR-II, 1000–1700 nm) is extensively used in both fundamental scientific research and clinical practice, owing to its advances of high sensitivity and high spatiotemporal resolution with increasing tissue penetration depths. Among several NIR-II fluorophores, recent accomplishments in biocompatible lanthanide-based luminescent nanomaterials have aroused great interest of researchers. This progress report summarizes recent progress in controlled synthesis of lanthanide-based NIR-II nanomaterials and their state-of-the-art in NIR-II biomedical imaging and biosensing applications. In addition, challenges and opportunities for this kind of novel NIR-II nanoprobes are also discussed.
关键词： lanthanides,bioimaging,NIR-II,near infrared imaging,fluorescence,nanoparticles
更新于2025-09-23 15:22:29
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Rhenium and technetium-complexed silicon rhodamines as near-infrared imaging probes for bimodal SPECT- and optical imaging
摘要： Fluorescent Si-rhodamines were modified to enable complexation with the Re(I)- and 99mTc(I)-tricarbonyl core. The corresponding complexes exhibit suitable properties as bimodal imaging probes for SPECT- and optical imaging in vitro. Importantly, the novel in aqueous solution stable, functionalized Si-rhodamines retain favourable optical properties after complexation (QY=0.09, λabs=654 nm, λem=669 nm in PBS) and show promising near-infrared optical properties for potential in vivo applications enabling bimodal scintigraphic imaging and optical imaging, e.g. used in radio- and fluorescence-guided tumor resection.
关键词： SPECT,Optical imaging,Near-infrared imaging,Technetium,Rhenium,Silicon rhodamines
更新于2025-09-23 15:21:01
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Near-infrared fluorescence-guided surgery using indocyanine green facilitates secure infrapyloric lymph node dissection during laparoscopic distal gastrectomy
摘要： Purpose We aimed to investigate the usefulness of near-infrared indocyanine green (ICG)-enhanced fluorescence guidance for infrapyloric LN dissection in laparoscopic distal gastrectomy. Methods This study enrolled patients with early gastric cancer scheduled for laparoscopic distal gastrectomy. After intra-operative submucosal injection of ICG (0.1 mg/mL), LN dissection was conducted under near-infrared ICG fluorescence guidance. The operation time, bleeding events during infrapyloric LN dissection were analyzed. Cases were retrospectively 1:3 propensity-score matched to patients who underwent laparoscopic distal gastrectomy without ICG injection. Results The mean time from midline omentectomy to exposure of the right gastroepiploic vein was significantly shorter in the ICG group (n = 20) than in the non-ICG group (n = 60) (13.05 ± 5.77 vs 18.68 ± 7.92 min; p = 0.001), and the incidence of bleeding during infrapyloric LN dissection was lower in the ICG group (20% vs 68.3%, p < 0.001). The two groups did not differ significantly regarding the number of LNs retrieved from the infrapyloric area (p = 0.434). Conclusions Near-infrared ICG fluorescence guidance facilitates safe and fast infrapyloric LN dissection in laparoscopic distal gastrectomy.
关键词： Indocyanine green,Laparoscopic surgery,Lymph node dissection,Near-infrared imaging,Gastric cancer
更新于2025-09-23 15:21:01
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Comparing fundus autofluorescence and infrared imaging findings of peripheral retinoschisis, schisis detachment, and retinal detachment
摘要： Purpose: The primary goal of this study was to identify characteristic features of peripheral degenerative retinoschisis (RS), schisis detachment (SD) and retinal detachment (RD) on both fundus autofluorescence (FAF) and infrared (IR) imaging, using spectral domain optical coherence tomography (SD-OCT) imaging of the peripheral retina as the confirmatory imaging tool. Methods: This is a descriptive case series study. A total of 27 eyes of 22 patients were included. Thirteen eyes of 10 patients diagnosed with RS, 4 eyes of 3 patients diagnosed with SD, and 10 eyes of 9 patients diagnosed with RD were included. Patients with images of poor quality were excluded. Heidelberg Spectralis HRA + OCT machine (Heidelberg Engineering, Heidelberg, Germany) were used to acquire the images. Results: All conditions appeared as areas of hypo-AF on FAF and hypo-reflectance on IR imaging. Accentuated vasculature of the lesion was noted with IR imaging due to elevation of the RS and RD, which was less frequently observed with FAF. On FAF, a hyper-AF leading edge around the RS lesion indicated the presence of intraretinal or subretinal fluid and an extension of the RS. Retinal breaks/holes were best visualized with IR imaging. SD-OCT confirmed the diagnosis in all performed cases. Conclusions: We were unable to differentiate between RS and RD based solely on findings from FAF and IR imaging. However, the combination of them with SD-OCT can assist in the diagnosis of RS from RD and in the evaluation of RS progression. OCT remains the main modality imaging to differentiate these conditions.
关键词： Retinoschisis,Retinal detachment,Fundus autofluorescence,Infrared imaging,Spectral domain optical coherence tomography,Schisis detachment
更新于2025-09-23 15:21:01