imaging system resolution depends upon Fλ/d where F is the focal ratio, X is the wavelength, and d is the detector size. Assuming a 100% fill factor, no aliasing occurs when Fλ/d > 2. However, sampling artifacts ...
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ISBN:
(纸本)9780819468604
imaging system resolution depends upon Fλ/d where F is the focal ratio, X is the wavelength, and d is the detector size. Assuming a 100% fill factor, no aliasing occurs when Fλ/d > 2. However, sampling artifacts are quite acceptable and most systems have Fλ/d < 1. Sampling artifacts are most noticeable with periodic targets (bar patterns, picket fences, plowed fields, etc). Since real targets are aperiodic, the sampling theorem (frequency domain analysis) does not directly provide guidance in algorithm development. Sampling creates an edge location ambiguity of one pixel. Phasing effects and edge ambiguity are often overlooked when designing image processingalgorithms.
yyDespite tremendous efforts to avoid them, stripes are a re-occurring problem for many remote imaging sensors. Much work has focused on suppressing or eliminating them in order to recover accurate observed radiances....
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ISBN:
(纸本)9780819468314
yyDespite tremendous efforts to avoid them, stripes are a re-occurring problem for many remote imaging sensors. Much work has focused on suppressing or eliminating them in order to recover accurate observed radiances. Beyond the obvious need to eliminate stripes to obtain accurate scientific measurements, stripes can also significantly impact the performance of compression algorithms. Many compression algorithms are based on linear representations of image space or assume the data to be relatively smooth. In contrast stripes produce nonlinearities in the data as well as sharp discontinuities which make it seem necessary to describe the images with many parameters. Yet the sources and nature of the stripes are often not well known, they could come from specific irregularities with the sensors. If the a priori construction of the sensor is accounted for, and the stripe statistically modeled. it is possible to transmit the stripe parameters separately along with de-striped images. The de-striped images have image statistics whose assumptions are much closer to those for which standard compression algorithms are optimized. As an example, we show this yields a significant boost in the performance of these algorithms when applied to the de-striped MODIS images.
The range and scope of electro-optical (EO) sensor systems within security and surveillance (S&S) is growing, and this places a corresponding demand on the image processing functionality required to meet end users...
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ISBN:
(纸本)9780819468994
The range and scope of electro-optical (EO) sensor systems within security and surveillance (S&S) is growing, and this places a corresponding demand on the image processing functionality required to meet end users' requirements. Increasingly, these requirements include the ability to monitor wide areas with multiple affordable cameras, and for good quality imagery to be available 24-hours a day. This paper presents the results from some real-time systems which offer this capability, and focuses on a number of the image processing techniques used to deliver a high-quality, wide-angle, day/night capability. These include the production of a seamless image mosaic from multiple sensors, the removal of artefacts from scenes, enhancements to-take account of changing environmental conditions, and a means of allowing the system to automatically focus on an area of interest highlighted by an operator. In addition, the cost of some high-performance S&S systems may be reduced by omitting physical calibration elements and performing sensor calibration using scene-derived data instead, and so a method for achieving this is also reported. The paper considers both the theoretical aspects of the algorithms presented and the issues involved-in real-time implementation for S&S applications.
The proceedings contain 18 papers. The topics discussed include;phase and frequency stability for synthetic aperture LADAR;signal-to-noise ratios of coherent imaging LADAR;technical assessment of a 100W CW fiber laser...
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ISBN:
(纸本)9780819468604
The proceedings contain 18 papers. The topics discussed include;phase and frequency stability for synthetic aperture LADAR;signal-to-noise ratios of coherent imaging LADAR;technical assessment of a 100W CW fiber laser amplifier for fourier telescopy imaging;hyper-spectral imaging using an optical fiber transition element;a comparative study of algorithms for radar imaging from gapped data;estimating object shape from return flux measurements using a sinusoid beam dither method;sampling artifacts, system design, and imagingprocessing;new approaches to image super-resolution beyond the diffraction limit;digital and optical superresolution of low-resolution image-sequences;fourier image sharpness sensor for high-speed wavefront sensing;real time phase diversity advanced image processing and wavefront sensing;piston phase error due to bending of delivery fiber;and range estimation based on multiple imaging.
Multispectral imaging is becoming an increasingly important tool for monitoring the earth and its environment from space borne and airborne platforms. Multispectral imaging data consists of visible and IR measurements...
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ISBN:
(纸本)9780819468314
Multispectral imaging is becoming an increasingly important tool for monitoring the earth and its environment from space borne and airborne platforms. Multispectral imaging data consists of visible and IR measurements from a scene across space and spectrum. Growing data rates resulting from faster scanning and finer spatial and spectral resolution makes compression an increasingly critical tool to reduce data volume for transmission and archiving. Examples of multispectral sensors we consider include the NASA 36 band MODIS imager, Meteosat 2nd generation 12 band SEVIRI imager, GOES R series 16 band ABI imager, current generation GOES 5 band imager, and Japan's 5 band MTSAT imager. Conventional lossless compression algorithms are not able to reach satisfactory compression ratios nor are they near the upper limits for lossless compression on imager data as estimated from the Shannon entropy. We introduce a new lossless compression algorithm developed for the NOAA-NESDIS satellite based Earth science multispectral imagers. The algorithm is based on capturing spectral correlations using spectral prediction, and spatial correlations with a linear transform encoder. The algorithm as presented has been designed to work with NOAA's scientific data and so is purely lossless but lossy modes can be supported. The compression algorithm also structures the data in a way that makes it easy to incorporate robust error correction using FEC coding methods as TPC and LDPC for satellite use. This research was funded by NOAA-NESDIS for its Earth observing satellite program and NOAA goals.
Useful diagnosis of lung lesions in computed tomography (CT) depends on many factors including the ability of radiologists to detect and correctly interpret the lesions. Computer-aided Diagnosis (CAD) systems can be u...
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ISBN:
(纸本)9780819466303
Useful diagnosis of lung lesions in computed tomography (CT) depends on many factors including the ability of radiologists to detect and correctly interpret the lesions. Computer-aided Diagnosis (CAD) systems can be used to increase the accuracy of radiologists in this task. CAD systems are, however, trained against ground truth and the mechanisms employed by the CAD algorithms may be distinctly different from the visual perception and analysis tasks of the radiologist. In this paper, we present a framework for finding the mappings between human descriptions and characteristics and computed image features. The data in our study were generated from 29 thoracic CT scans collected by the Lung Image Database Consortium (LIDC). Every case was annotated by up to 4 radiologists by marking the contour of nodules and assigning nine semantic terms to each identified nodule;fifty-nine image features were extracted from each segmented nodule. Correlation analysis and stepwise multiple regression were applied to find correlations among semantic characteristics and image features and to generate prediction models for each characteristic based on image features. From our preliminary experimental results, we found high correlations between different semantic terms (margin, texture), and promising mappings from image features to certain semantic terms (texture, lobulation, spiculation, malignancy). While the framework is presented with respect to the interpretation of pulmonary nodules in CT images, it can be easily extended to find mappings for other modalities in other anatomical structures and for other image features.
This paper considers the effect of using different probe and gallery sensors on the performance of 3D face recognition. We report results of recognition experiments using face scans of 120 different persons, taken wit...
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ISBN:
(纸本)0819462586
This paper considers the effect of using different probe and gallery sensors on the performance of 3D face recognition. We report results of recognition experiments using face scans of 120 different persons, taken with two different commercial scanners, each at two different times. Our matching algorithm is a version of ICP, which is a popular approach to 3D face recoanition. We find substantial differences in recognition rate between the sensors considered in part due to the different C types of imaging artifacts produced. When matching data across sensors, the higher-quality data should be the enrollment data.
This paper proposed a novel scheme for early breast cancer detection using UWB microwave imaging. By applying the CLEAN algorithm to process the received signals at each sensor, the IR components can be successfully r...
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ISBN:
(纸本)1424401224
This paper proposed a novel scheme for early breast cancer detection using UWB microwave imaging. By applying the CLEAN algorithm to process the received signals at each sensor, the IR components can be successfully resolved. The locations and scattering strengths of dominant scatterers are then estimated based on the TOA data fusion concept. Simulation results have indicated the feasibility of detecting a tumor of 2 mm at depth of 2 cm. As compared to the existing techniques, the proposed approach is more computationally-efficient since the scanning process is localized at a few candidate locations. A number of issues that need to be addressed in future include: (i) effectiveness of the proposed approach for 3-D phantoms with realistic breast shapes and tissue compositions; (ii) extension of analysis to more complicated antenna array systems; (iii) other signal processingalgorithms that may provide better IR component extraction and scatterer location estimation
The Civil Air Patrol (CAP) is procuring Airborne Real-time Cueing Hyperspectral Enhanced Reconnaissance (ARCHER) systems to increase their search-and-rescue mission capability. These systems are being installed on a f...
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ISBN:
(纸本)0819457914
The Civil Air Patrol (CAP) is procuring Airborne Real-time Cueing Hyperspectral Enhanced Reconnaissance (ARCHER) systems to increase their search-and-rescue mission capability. These systems are being installed on a fleet of Gippsland GA-8 aircraft, and will position CAP to gain real-world mission experience with the application of hyperspectral sensor and processing technology to search and rescue. The ARCHER system design, data processing, and operational concept leverage several years of investment in hyperspectral technology research and airborne system demonstration programs by the Naval Research Laboratory (NRL) and Air Force Research Laboratory (AFRL). Each ARCHER system consists of a NovaSol-designed, pushbroom, visible/near-infrared (VNIR) hyperspectral imaging (HSI) sensor, a co-boresighted visible panchromatic high-resolution imaging (HRI) sensor, and a CMIGITS-iii GPS/INS unit in an integrated sensor assembly mounted inside the GA8 cabin. ARCHER incorporates an on-board data processing system developed by Space Computer Corporation (SCC) to perform numerous real-time processing functions including data acquisition and recording, raw data correction, target detection, cueing and chipping, precision image geo-registration, and display and dissemination of image products and target cue information. A ground processing station is provided for post-flight data playback and analysis. This paper describes the requirements and architecture of the ARCHER system, with emphasis on data processor design, components, software, interfaces, and displays. Key sensor performance characteristics and real-time data processing features are discussed. The use of the system for detecting and geo-locating ground targets in real-time is demonstrated using test data collected in Southern California in the fall of 2004.
The Civil Air Patrol (CAP) is procuring Airborne Real-time Cueing Hyperspectral Enhanced Reconnaissance (ARCHER) systems to increase their search-and-rescue mission capability. These systems are being installed on a f...
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ISBN:
(纸本)0819457728
The Civil Air Patrol (CAP) is procuring Airborne Real-time Cueing Hyperspectral Enhanced Reconnaissance (ARCHER) systems to increase their search-and-rescue mission capability. These systems are being installed on a fleet of Gippsland GA-8 aircraft, and will position CAP to gain real-world mission experience with the application of hyperspectral sensor and processing technology to search and rescue. The ARCHER system design, data processing, and operational concept leverage several years of investment in hyperspectral technology research and airborne system demonstration programs by the Naval Research Laboratory (NRL) and Air Force Research Laboratory (AFRL). Each ARCHER system consists of a NovaSol-designed, pushbroom, visible/near-infrared (VNIR) hyperspectral imaging (HSI) sensor, a co-boresighted visible panchromatic high-resolution imaging (HRI) sensor, and a CMIGITS-iii GPS/INS unit in an integrated sensor assembly mounted inside the GA-8 cabin. ARCHER incorporates an on-board data processing system developed by Space Computer Corporation (SCC) to perform numerous real-time processing functions including data acquisition and recording, raw data correction, target detection, cueing and chipping, precision image geo-registration, and display and dissemination of image products and target cue information. A ground processing station is provided for post-flight data playback and analysis. This paper describes the requirements and architecture of the ARCHER system, including design, components, software, interfaces, and displays. Key sensor performance characteristics and real-time data processing features are discussed in detail. The use of the system for detecting and geo-locating ground targets in real-time is demonstrated using test data collected in Southern California in the fall of 2004.
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