- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Multi-Spectral Water Index (MuWI): A Native 10-m Multi-Spectral Water Index for Accurate Water Mapping on Sentinel-2
摘要： Accurate water mapping depends largely on the water index. However, most previously widely-adopted water index methods are developed from 30-m resolution Landsat imagery, with low-albedo commission error (e.g., shadow misclassified as water) and threshold instability being identified as the primary issues. Besides, since the shortwave-infrared (SWIR) spectral band (band 11) on Sentinel-2 is 20 m spatial resolution, current SWIR-included water index methods usually produce water maps at 20 m resolution instead of the highest 10 m resolution of Sentinel-2 bands, which limits the ability of Sentinel-2 to detect surface water at finer scales. This study aims to develop a water index from Sentinel-2 that improves native resolution and accuracy of water mapping at the same time. Support Vector Machine (SVM) is used to exploit the 10-m spectral bands among Sentinel-2 bands of three resolutions (10-m; 20-m; 60-m). The new Multi-Spectral Water Index (MuWI), consisting of the complete version and the revised version (MuWI-C and MuWI-R), is designed as the combination of normalized differences for threshold stability. The proposed method is assessed on coincident Sentinel-2 and sub-meter images covering a variety of water types. When compared to previous water indexes, results show that both versions of MuWI enable to produce native 10-m resolution water maps with higher classification accuracies (p-value < 0.01). Commission and omission errors are also significantly reduced particularly in terms of shadow and sunglint. Consistent accuracy over complex water mapping scenarios is obtained by MuWI due to high threshold stability. Overall, the proposed MuWI method is applicable to accurate water mapping with improved spatial resolution and accuracy, which possibly facilitates water mapping and its related studies and applications on growing Sentinel-2 images.
关键词： MNDWI,OSH,SVM,AWEI,water mapping,water classification,shadow,NDWI,Sentinel-2,MuWI,Landsat,water index,multi-spectral water index,sunglint,machine learning
更新于2025-09-23 15:21:01
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Optical scanning holography for tumor extraction from brain magnetic resonance images
摘要： Tumor segmentation from magnetic resonance images (MRI) is an error-prone and time-absorbing process. Recently, optical methods have opened a new avenue to tack with the aforementioned problem. In this paper, we propose a novel architecture adapting the Optical Scanning Holography (OSH) to the detection of the abnormal tissue regions in MRI. The proposed method combines an o?-axis optical scan, performed by a heterodyne fringe pattern, and a MR image display ensured by a spatial light modulator. The output in-phase component of the scanned current is collected digitally. Hence, a high-precision distribution of biological tissues is extracted using this in-phase component. Its maximum position is exactly the one of the tumor. Meanwhile, this position is used in an Active Contour Model (ACM) to perform a fast segmentation of the extent corresponding to the tumors. Several images of brain tumors from BRATS database, with tumors having di?erent contrast and form, are used to test the proposed system. Parameters reverted by the optical process are used to investigate the detection performance. Further, in terms of tumor segmentation, the proposed OSH-ACM process has high performance metrics compared to some of recently published method. The underlying physics of the precision superiority, presented by the OSH-ACM, is the high-precision extraction of the abnormal tissue regions by the in-phase component of the scanned current.
关键词： Active contour,Optical Scanning Holography (OSH),Segmentation,Brain tumor detection,In-phase component of the scanned current
更新于2025-09-23 15:21:01
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Review on feature extraction for 3D incoherent image processing using optical scanning holography
摘要： The advancement of digital holography in the past 2 decades has enabled precise capturing of three-dimensional (3-D) images of physical objects. This important technology has been widely applied in numerous industrial sectors such as, but not limited to remote sensing, metrology, bio-medical imaging, advertising, and entertainment. Most of the hologram acquisition techniques developed to date are employing digital cameras for recording the hologram, hence imposing rigid restrictions on the size and resolution of the captured 3-D image. This limitation, however, is not found in optical scanning holography (OSH). Based on a scanning mechanism and a single pixel sensor, OSH is capable of capturing digital holograms of both macroscopic and microscopic, as well as fluorescent objects with high precision. Since its invention in the late 70s, numerous research works have been conducted to enhance this technology, optimizing important factors such as acquisition speed, precision, data size, and security. The objective of this review paper is to provide a walkthrough of the state-of-the-art of the OSH technology, from its original principle, to different variants that have been developed over the years with emphasis on their feature extraction capabilities under the incoherent mode of operation. Whenever possible, we shall provide the key formulations of each approach, and experimental outcomes for demonstrating the pros and cons of the method.
关键词： generalized two-pupil image processing system,spiral-phase pupil,anisotropic edge detection,feature extraction,annular pupil,Optical Scanning Holography (OSH)
更新于2025-09-12 10:27:22