During the last two decades, Single Instruction Multiple Data (SIMD) processors have become important architectures in embedded systems for imageprocessing applications. The main reasons are their area and energy eff...
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During the last two decades, Single Instruction Multiple Data (SIMD) processors have become important architectures in embedded systems for imageprocessing applications. The main reasons are their area and energy efficiency. Often the processing elements (PEs) of an SIMD processor are only locally connected. This may result in a communication bottleneck (only access to direct neighbors). One way to solve this is to use a fully connected communication network (FC-SIMD) between PEs. However, this solution leads to an excessive communication area cost, low communication network utilization, and scalability problems. E.g., the area overhead of an FC-SIMD is more than 100% when the number of PEs gets bigger than *** this paper, we introduce a new type of SIMD architecture, called RC-SIMD, with a reconfigurable communication network. It uses a delay-line in the instruction bus, causing the accesses to the communication network to be distributed over time. This architecture requires only a very cheap communication network while performing almost the same as expensive FC-SIMD ***, the new architecture causes irregular resource conflicts. We therefore introduce a conflict model that existing schedulers are able to cope with. Experimental results show that, on average (compared to locally connected SIMDs), RC-SIMD require 21% fewer cycles than architecture without the delay-line, while the area overhead is at most 10%.
Conduction welding offers an alternative to keyhole welding. Compared with keyhole welding, it is an intrinsically stable process because vaporization phenomena are minimal. However, as with keyhole welding, an on-lin...
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Conduction welding offers an alternative to keyhole welding. Compared with keyhole welding, it is an intrinsically stable process because vaporization phenomena are minimal. However, as with keyhole welding, an on-line process-monitoring system is advantageous for quality assurance to maintain the required penetration depth, which in conduction welding is more sensitive to changes in heat sinking. The maximum penetration is obtained when the surface temperature is just below the boiling point, and so we normally wish to maintain the temperature at this level. We describe a two-color optical system that we have developed for real-time temperature profile measurement of the conduction weld pool. The key feature of the system is the use of a complementary metal-oxide semiconductor standard color camera leading to a simplified low-cost optical setup. We present and discuss the real-time temperature measurement and control performance of the system when a defocused beam from a high power Nd:YAG laser is used on 5 mm thick stainless steel workpieces. (c) 2005 Optical Society of America.
Eye tracking is one of the latest technologies that has shown potential in several areas, including biometrics;human-computer interactions for people with and without disabilities;and noninvasive monitoring, detection...
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Eye tracking is one of the latest technologies that has shown potential in several areas, including biometrics;human-computer interactions for people with and without disabilities;and noninvasive monitoring, detection, and even diagnosis of physiological and neurological problems in individuals. Current noninvasive eye-tracking methods achieve a 30-Hz rate with a low accuracy in gaze estimation, which is insufficient for many applications. We propose a new noninvasive optical eye-tracking system that is capable of operating at speeds as high as 6-12 kHz. A new CCD video camera and hardware architecture are used, and a novel fast algorithm leverages specific features of the input CCD camera to yield a real-time eye-tracking system. A field-programmable gate array is used to control the CCD camera and to execute the operations. Initial results show the excellent performance of our system under severe head-motion and low-contrast conditions. (C) 2005 Optical Society of America.
We analyze the estimation precision of the parameter of the orthogonal state contrast image (OSCI) under coherent illumination. This parameter represents the degree of polarization of the light if the materials that c...
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We analyze the estimation precision of the parameter of the orthogonal state contrast image (OSCI) under coherent illumination. This parameter represents the degree of polarization of the light if the materials that compose the scene are purely depolarizing. Two different estimation modes are considered, depending on the uniformity of the illumination of the scene. We first determine lower bounds on the estimation precision in both cases by computing the Cramer-Rao lower bounds (CRLBs) for unbiased estimation. This allows us to compare the potential precision that can be reached in each mode. We then consider the estimators based on empirical averaging of the data, and we show that there are cases where they are strongly biased. We thus propose and characterize another estimator based on the natural representation of the OSCI, which is asymptotically unbiased and whose variance is close to the unbiased CRLB. (c) 2005 Optical Society of America.
Closely related to the development process of novel image processing algorithms is always the need for a systematic training and evaluation of these methods. Thus, a predefined set of images (so-called reference image...
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High precision, repeatability, and quality are the three vital requirements in laser welding production. For accurate real-time tracking and inspecting the laser welding process, the high-performance sensors are extre...
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ISBN:
(纸本)0819455881
High precision, repeatability, and quality are the three vital requirements in laser welding production. For accurate real-time tracking and inspecting the laser welding process, the high-performance sensors are extremely demanded. Monitored signal reliability can be significantly increased by using high resolution, digital CMOS sensors and high-speed, real-time imageprocessing technologies. This feature presents the latest developments in high-performance optical joint tracking systems and optical inspection systems based on these technologies. Using a coaxially aligned CMOS imaging detector, the optical signals emission of the plasma during CO2 laser welding was studied. The camera images taken from the process were analyzed with image-processingalgorithms. Compared with the lateral systems, coaxial arrangement of the camera allows observing the significant process characteristics. Experimental evidence shows that the system can monitor the instability of the keyhole, the gap caused by the welding distortion, and the deviations from the desired welding path. By the image analysis, the spatially distribution intensity of the plasma emission was analyzed, and it can be correlated to the penetration state and the penetration depth. Thus the laser welding process and the weld quality can be evaluated.
Determining the effective MTF, SNR and Sensor geometries of multi-aperture computational imaging architectures will allow the National image Interpretability Rating Scale to be applied to computational imagers. An app...
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We present an imaging system that measures the polarimetric state of the light coming from each point of a scene. This system, which determines the four components of the Stokes vector at each spatial location, is bas...
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We present an imaging system that measures the polarimetric state of the light coming from each point of a scene. This system, which determines the four components of the Stokes vector at each spatial location, is based on a liquid-crystal polarization modulator, which makes it possible to acquire four-dimensional Stokes parameter images at a standard video rate. We show that using such polarimetric images instead of simple intensity images can improve target detection and segmentation performance. (C) 2004 Optical Society of America.
This paper discusses the dependences that make it possible to determine the viewing range when a television device is used for driving in the nocturnal regime. (C) 2004 Optical Society of America.
This paper discusses the dependences that make it possible to determine the viewing range when a television device is used for driving in the nocturnal regime. (C) 2004 Optical Society of America.
Issues associated with the radar detection of military targets that are concealed or camouflaged by forest clutter are described. The specific sensor platform can be categorized as an ultrawideband (UWB) foliage penet...
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Issues associated with the radar detection of military targets that are concealed or camouflaged by forest clutter are described. The specific sensor platform can be categorized as an ultrawideband (UWB) foliage penetration (FOPEN) synthetic aperture radar (SAR). The discussion illustrates the fact that many contemporary approaches to FOPEN target detection Are computationally intensive and/or require the implementation of elaborate training procedure's. Alternative approaches, based the application of a set of simple rank-order filters (alternately known as order statistical or L filters), are presented. Initial results indicate impressive performance levels (in terms of probability of detection as a function of false-alarm rate) with respect to baseline constant false-alarm rate computations. A number of avenues for future investigations are cited.
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