Journal Paper - 2017 by CHIMAN KWAN
Journal of Signal, Image, and Video Processing, 2017
Bayer pattern has been widely used in commercial digital cameras. In NASA's mast camera (Mastcams... more Bayer pattern has been widely used in commercial digital cameras. In NASA's mast camera (Mastcams) onboard the Mars rover Curiosity, Bayer pattern has also been used in capturing the RGB bands. It is well known that debayering, also known as demosaicing in the literature, introduces artifacts such as false colors and zipper edges. In this paper, we first present four fusion approaches, including weighted and the well-known alpha-trimmed mean filtering approaches. Each fusion approach combines demosaicing results from seven debayering algorithms in the literature, which are selected based on their performance mentioned in other survey papers and the availability of open source codes. Second, we present debayering results using two benchmark image data sets: IMAX and Kodak. It was observed that none of the seven algorithms in the literature can yield the best performance in terms of peak signal-to-noise ratio (PSNR), CIELAB score, and subjective evaluation. Although the fusion algorithms are simple, it turns out that the debayering performance can be improved quite dramatically after fusion based on our extensive evaluations. In particular, the average PSNR improvements of the weighted fusion algorithm over the best individual method are 1.1 dB for the IMAX database and 1.8 dB for the Kodak database, respectively. Third, we applied the various algorithms to 36 actual Mastcam images. Subjective evaluation indicates that the fusion algorithms still work well, but not as good as the existing debayering algorithm used by NASA.
IEEE Geoscience and Remote Sensing Letters, 2017
WorldView 3 (WV-3) is the first commercially deployed super-spectral, very high-resolution (HR) s... more WorldView 3 (WV-3) is the first commercially deployed super-spectral, very high-resolution (HR) satellite. However , the resolution of the shortwave infrared (SWIR) bands is much lower than that of the other bands. In this letter, we describe four different approaches, which are combinations of pansharpening and hypersharpening methods, to generate HR SWIR images. Since there are no ground truth HR SWIR images, we also propose a new picture quality predictor to assess hypersharpening performance, without the need for reference images. We describe extensive experiments using actual WV-3 images that demonstrate that some approaches can yield better performance than others, as measured by the proposed blind image quality assessment model of hypersharpened SWIR images.
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 2017
The Mars Science Laboratory is a robotic rover mission to Mars launched by NASA on November 26, 2... more The Mars Science Laboratory is a robotic rover mission to Mars launched by NASA on November 26, 2011, which successfully landed the Curiosity rover in Gale Crater on August 6, 2012. The Curiosity rover has two mast cameras (Mastcams) that acquire stereo images at a number of different wavelengths. Each camera has nine bands of which six bands are overlapped in the two cameras. These acquired stereo band images at different wavelengths can be fused into a 12-band multispectral image cube, which could be helpful to guide the rover to interesting locations. Since the two Mastcams' fields of view are three times different from each other, in order to fuse the left-and right-camera band images to form a multispectral image cube, there is a need for a precise image alignment of the stereo images with registration errors at the subpixel level. A two-step image alignment approach with a novel utilization of existing image registration algorithms is introduced in this paper and is applied to a set of Mastcam stereo images. The effect of the two-step alignment approach using more than 100 pairs of Mastcam images, selected from over 500000 images in NASA's Planetary Data System database, clearly demonstrated that the fused images can improve pixel clustering and anomaly detection performance. In particular, registration errors in the subpixel level are observed with the applied alignment approach. Moreover, the pixel clustering and anomaly detection performance have been observed to be better when using fused images.
Adv. Sci. Technol. Eng. Syst. J. , 2017
This paper proposes a novel approach to sensor and actuator integrity monitoring in a dynamic sys... more This paper proposes a novel approach to sensor and actuator integrity monitoring in a dynamic system. Multiple sensor and actuator faults can be detected. Furthermore, faulty sensors and actuators are isolated by contribution analysis. Most importantly, fault magnitudes can be correctly estimated and failed sensors or actuators outputs can be reconstructed. The proposed approach is robust to disturbances, minimizes false alarms, while achieving maximized sensitivity to any faults. Numerical examples justify correctness and validity of the developed methodology.
J. Appl. Remote Sens. , 2017
This paper presents a practical approach to target detection for hyperspectral images. In target ... more This paper presents a practical approach to target detection for hyperspectral images. In target detection, it is normally assumed that the ground truth target signatures collected in a laboratory are available and one then uses them to search for targets in a given image. However, directly applying the laboratory signatures to the real data is not appropriate due to environmental differences between the ground truth data and real data. Conventional atmospheric compensation schemes such as the use of MODTRAN can help to improve the target detection performance. However, the computational load is huge and thus real-time applications may prohibit this compensation approach. We present results of an alternative compensation technique known as in-scene compensation, which is appealing as no complicated techniques such as MODTRAN are needed. Two in-scene methods for visible near-infra-red/short-wave infrared range have been developed in the literature: empirical line method (ELM) and vegetation normalization (VN). Both approaches have advantages and disadvantages. We propose a hybrid in-scene compensation method that can be considered as a combination of ELM and VN and we call our method ELM augmented VN (EAVN). One key advantage of EAVN is that it combines the advantages of ELM and VN and eliminates their disadvantages. Compared to ELM, there is no need for two or more known target pixels in the test scene. Compared to VN, there is no need for dark pixels. Extensive experimental results using ground-based sensor data showed that the EAVN algorithm provides excellent compensation to environmental changes. After compensation, the receiver operating characteristics performance of target detection has been significantly improved by orders of magnitude in a number of cases, as compared to two standard compensation methods: quick atmospheric correction and internal average relative reflectance correction.
Journal Paper - 2016 by CHIMAN KWAN
Journal of Sensors, 2016
Remote sensing and its applications have gained more and more attention from researchers in recen... more Remote sensing and its applications have gained more and more attention from researchers in recent years. One clear indicator can be seen from the 2016 International Geo-science and Remote Sensing Symposium (IGARSS), which has received over 3,000 papers. This field is expanding and evolving rapidly. The aim of this special issue is an attempt to capture a small section of recent advances in remote sensing. We would like to thank all the contributing authors, reviewers, and journal staffs for making this special issue a reality. As will be seen shortly, the 6 papers indeed cover a wide range of remote sensing applications using airborne and space-borne instruments. The paper by H. Li et al. addressed an important problem in many state-of-the-art multispectral airborne imagers. Due to significant difference in intensity between different band images, image registration becomes very difficult even though the multispectral imager consists of identical monochrome cameras equipped with different bandpass filters. The authors proposed a two-stage image registration algorithm. The first stage is to use phase correlation method to calculate the parameters of a coarse-offset relationship between different band images. The second stage uses the scale invariant feature transform (SIFT) to detect the feature points. Actual experimental data were used to demonstrate the proposed algorithm. It was seen that conventional SIFT-only method failed whereas the proposed method can still achieve good registration performance. Land cover land use (LCLU) classification is important for environment monitoring and urban planning. The paper by J. Jiao and Z. Deng focused on building and tree detection algorithms by using improved superpixels from large high-resolution urban aerial images. The authors also proposed a method to calculate the tree parameters using a cost function and information from shadows. Experiments showed that their method is fast and robust, while still being simple and efficient, and they also indicate that the shadow is a good feature to estimate the tree height. The results of proposed algorithms have great potential for generating 3D urban models. Airborne electromagnetic methods (AEM) systems are important for estimating abundance of natural resources. Typically, inductance is being measured using a rectangular loop onboard an aircraft. One serious problem with existing systems is that the effect of a finite-conducting ground on the inductance of the transmitting loop was neglected, or the ground was handled as a perfect conductor. In other words, there was no accurate method to evaluate ground's effect on the inductance of the transmitting loop. Consequently, the measurement will not be accurate. X. Jia et al. proposed a new and efficient algorithm to calculate ground's effect on the inductance of a rectangular loop. An experiment was constructed afield, showing that the inductance increased gradually when the loop was lifted up from 0 m to 30 m, which supported the algorithm positively. Using satellite data for generating vegetation profiles has the advantage of large area coverage. Due to the presence of clouds in the data, a composite 16-day period is normally used where at least a certain number of cloud free data are present. However, 16-day period vegetation profiles are less sensitive to real-time changes due to the composite period used for the bidirectional reflectance distribution function (BRDF) model. The paper by S. Kim et al. investigated the impact of different composite periods on the vegetation profiles. Geostationary Ocean Color Imager (GOCI) was
Journal of Signal, Image, and Video Processing, 2016
Assessment of damages due to fire, drought, flood, land slide, etc., using hyperspectral images f... more Assessment of damages due to fire, drought, flood, land slide, etc., using hyperspectral images from Hype-rion, AVIRIS or HyspIRI has challenging issues. The effects of different illumination, atmospheric conditions and varying sensor/target viewing geometries are some of these challenges. A common approach for target detection is to apply atmospheric correction algorithms to the radiance image data cube and then search within the atmospherically corrected image cube for the target reflectance signature of interest. One major issue with the above approach is that it is com-putationally demanding. In this paper, instead of applying atmospheric correction to the raw radiance data, we generate radiance profiles of burn scar for the observed atmospheric and illumination conditions at the time of the hyperspec-tral image data collection and form a radiance profile library using a nonlinear analytical model for radiative transfer and MODTRAN. The target detection has been performed by a spectral similarity technique which takes into consideration multiple radiance profile variants of the target of interest. The effectiveness of the radiance domain-based target detection approach on reducing the computation time has been demonstrated on burn scar detection using airborne AVIRIS image data.
SPIE Journal of Applied Remote Sensing, 2016
NASA has been planning a hyperspectral infrared imager mission which will provide global coverage... more NASA has been planning a hyperspectral infrared imager mission which will provide global coverage using a hyperspectral imager with 60-m resolution. In some practical applications, such as special crop monitoring or mineral mapping, 60-m resolution may still be too coarse. There have been many pansharpening algorithms for hyperspectral images by fusing high-resolution (HR) panchromatic or multispectral images with low-resolution (LR) hyperspectral images. We propose an approach to generating HR hyperspectral images by fusing high spatial resolution color images with low spatial resolution hyperspectral images. The idea is called hybrid color mapping (HCM) and involves a mapping between a high spatial resolution color image and a low spatial resolution hyperspectral image. Several variants of the color mapping idea, including global, local, and hybrid, are proposed and investigated. It was found that the local HCM yielded the best performance. Comparison of the local HCM with 10 state-ofthe-art algorithms using five performance metrics has been carried out using actual images from the air force and NASA. Although our HCM method does not require a point spread function (PSF), our results are comparable to or better than those methods that do require PSF. More importantly, our performance is better than most if not all methods that do not require PSF. After applying our HCM algorithm, not only the visual performance of the hyperspectral image has been significantly improved, but the target classification performance has also been improved. Another advantage of our technique is that it is very efficient and can be easily parallelized. Hence, our algorithm is very suitable for real-time applications.
Fluctuation and Noise Letters, 2016
The statistical-physics-based Kirchhoff-law–Johnson-noise (KLJN) key exchange offers a new and si... more The statistical-physics-based Kirchhoff-law–Johnson-noise (KLJN) key exchange offers a new and simple unclonable system for credit/debit card chip authentication and payment. The key exchange, the authentication and the communication are unconditionally secure so that neither mathematics-nor statistics-based attacks are able to crack the scheme. The ohmic connection and the short wiring lengths between the chips in the card and the terminal constitute an ideal setting for the KLJN protocol, and even its simplest versions offer unprecedented security and privacy for credit/debit card chips and applications of physical unclonable functions (PUFs).
IEEE Trans. Geoscience and Remote Sensing, 2016
The Reed–Xiaoli (RX) algorithm has been widely used as an anomaly detector for hyperspectral imag... more The Reed–Xiaoli (RX) algorithm has been widely used as an anomaly detector for hyperspectral images. Recently, kernel RX (KRX) has been proven to yield high performance in anomaly detection and change detection. In this paper, we present a generalization of the KRX algorithm. The novel algorithm is called cluster KRX (CKRX), which becomes KRX under certain conditions. The key idea is to group background pixels into clusters and then apply a fast eigendecomposition algorithm to generate the anomaly detection index. Both global and local versions of CKRX have been implemented. Application to anomaly detection using actual hyperspectral images is included. In addition to anomaly detection , the CKRX algorithm has been integrated with other prediction algorithms for change detection. Spatially registered visible and near-infrared hyperspectral images collected from a tower-based geometry have been used in the anomaly and change detection studies. Receiver operating characteristics curves and actual computation times were used to compare different algorithms. It was demonstrated that CKRX has comparable detection performance as KRX, but with much lower computational requirements. Index Terms—Anomaly detection, change detection algorithms , cluster kernel RX (CKRX), hyperspectral imaging, kernel RX (KRX), receiver operating characteristics (ROC), Reed–Xiaoli (RX).
Journal Paper - 2015 by CHIMAN KWAN
J. Multidisciplinary Engineering Science and Technology, 2015
Hyperspectral images have been used in anomaly and change detection applications such as search a... more Hyperspectral images have been used in anomaly and change detection applications such as search and rescue operations where it is critical to have fast detection. However, conventional Reed-Xiaoli (RX) algorithm [6] took about 600 seconds using a PC to finish the processing of an 800x1024 hyperspectral image with 10 bands. This is not acceptable for real-time applications. A more recent algorithm known as kernel RX (KRX) [7] achieves better detection performance than RX at the expense of computational cost. For example, for the same 800x1024 image with 10 bands, KRX took 15 hours to finish the processing. In this paper, we present a general framework for fast anomaly detection using RX and KRX algorithms. First, a fast data reduction scheme using Principal Component Analysis (PCA) is proposed. This method takes less than 1 second to finish and the performance degradation is minimal. Second, we propose several speed boosting options in the RX and KRX algorithms. These options include image sub-sampling, the use of block pixels, and background pixel sub-sampling. Actual hyperspectral image has been used in our studies. Receiver operating characteristics (ROC) curves and actual computation times were used to compare the various options. For the 800x1024x10 image, we were able to improve the speed by more than 220 times for RX and 700 times for KRX with minimal degradation in detection performance.
J. Multidisciplinary Engineering Science and Technology, 2015
Past estimates of chemical element concentration from investigations on the surface of Mars by Al... more Past estimates of chemical element concentration from investigations on the surface of Mars by Alpha-Particle X-ray Spectrometer (APXS) instrument have been conducted by converting the peak areas of the characteristic element lines into element concentrations using look-up calibration tables. In this work, we have investigated the feasibility of applying a linear spectral unmixing technique, NCLS (Nonnegatively Constrained Least Squares) to APXS spectra data for concentration estimation. A procedure for signature calibration with the NCLS technique is also introduced in this work. Estimates using NCLS are highly accurate in comparison to the applied benchmark technique, PLS (Partial Least Squares) in a leave-one-out testing framework that uses 11 geostandards. Future work will consider the performance comparison with a peak-area based concentration estimation method, and whether the fusion of the two methods can further increase the correct concentration estimation accuracy.
Journal Paper - 2013 by CHIMAN KWAN
Fluctuation and Noise Letters, 2013
Weak unclonable function (PUF) encryption key means that the manufacturer of the hardware can clo... more Weak unclonable function (PUF) encryption key means that the manufacturer of the hardware can clone the key but not anybody else. Strong unclonable function (PUF) encryption key means that even the manufacturer of the hardware is unable to clone the key. In this paper, first we introduce an " ultra " strong PUF with intrinsic dynamical randomness, which is not only unclonable but also gets renewed to an independent key (with fresh randomness) during each use via the unconditionally secure key exchange. The solution utilizes the Kirchhoff-law-Johnson-noise (KLJN) method for dynamical key renewal and a one-time-pad secure key for the challenge/response process. The secure key is stored in a flash memory on the chip to provide tamper-resistance and nonvolatile storage with zero power requirements in standby mode. Simplified PUF keys are shown: a strong PUF utilizing KLJN protocol during the first run and noise-based logic (NBL) hyperspace vector string verification method for the challenge/response during the rest of its life or until it is re-initialized. Finally, the simplest PUF utilizes NBL without KLJN thus it can be cloned by the manufacturer but not by anybody else.
Sensors and Actuators B Journal, 2013
The feasibility of fluctuation-enhanced sensing (FES) for the detection and classification of dif... more The feasibility of fluctuation-enhanced sensing (FES) for the detection and classification of different gases using a single chemiresistive microsensor has been investigated through experimental measurements and data analyses. A nanostructured semiconducting metal oxide film has been used as a chemiresistive sensor in the experiments. Similarity fingerprints have been introduced to be used with the FES signatures, and combining similarity fingerprints with slope fingerprints results in a considerable increase in the classification accuracy attained by both Linear Discriminant Analysis (LDA) and Support Vector Machine (SVM) classification techniques.
Weak physical uncloneable function (WPUF) encryption key means that the manufacturer of the hardw... more Weak physical uncloneable function (WPUF) encryption key means that the manufacturer of the hardware can clone the key but anybody else is unable to so that. Strong physical uncloneable function (SPUF) encryption key means that even the manufacturer of the hardware is unable to clone the key. In this paper, first we introduce a "ultra"-strong PUF with intrinsic dynamical randomness, which is not only not cloneable but it also gets renewed to an independent key (with fresh randomness) during each use via the unconditionally secure key exchange. The solution utilizes the Kirchhoff-law-Johnson-noise (KLJN) method for dynamical key renewal and a one-time-pad secure key for the challenge/response process. The secure key is stored in a flash memory on the chip to provide tamper-resistance and non-volatile storage with zero power requirements in standby mode. Simplified PUF keys are shown: a strong PUF utilizing KLJN protocol during the first run and noise-based logic (NBL) hyperspace vector string verification method for the challenge/response during the rest of its life or until it is re-initialized. Finally, the simplest PUF utilizes NBL without KLJN thus it can be cloned by the manufacturer but not by anybody else.
Fluctuation enhanced sensing (FES) with a nanostructured, semiconducting metal oxide film for gas detection and classification
The feasibility of fluctuation-enhanced sensing (FES) for the detection and classification of dif... more The feasibility of fluctuation-enhanced sensing (FES) for the detection and classification of different gases using a single chemiresistive microsensor has been investigated through experimental measurements and data analyses. A nanostructured semiconducting metal oxide film has been used as a chemiresistive sensor in the experiments. Similarity fingerprints have been introduced to be used with the FES signatures, and combining similarity fingerprints with slope fingerprints results in a considerable increase in the classification accuracy attained by both Linear Discriminant Analysis (LDA) and Support Vector Machine (SVM) classification techniques.
Journal Paper - 2012 by CHIMAN KWAN
IEEE Trans. Industry Applications, 2012
Con Edison experiences more than 1000 arcing faults on its secondary distribution system each yea... more Con Edison experiences more than 1000 arcing faults on its secondary distribution system each year. Arcing faults introduce strong harmonics into the power network. We propose a fast, low-cost, and high-performance approach to locating arcing faults based on harmonics. First, we implemented two novel algorithms. One is based on the voltage ratio of harmonics. This method can detect arcing fault one at a time. The second one is based on sparse sensing, which is a powerful technique that can detect multiple faults and is robust to measurement noise. Both methods require low-cost voltage measurements; no high-cost sensors are required. In addition, the computations can be done very quickly within a few cycles (< 50 ms). Second, we have performed extensive simulation studies using the IEEE 14-bus system, IEEE 18-bus system, IEEE 118-bus system, and a 454-bus system. We only need to measure the voltages of a small percentage of the nodes. For example, voltages from only 20% of the nodes in a 454-bus system are needed for accurate fault location. Multiple simultaneous faults can be located. All the results clearly demonstrated the location accuracy of our algorithms.
Fluctuation and Noise Letters, 2012
Fluctuation-enhanced sensing (FES) comprises the analysis of the stochastic component of the sens... more Fluctuation-enhanced sensing (FES) comprises the analysis of the stochastic component of the sensor signal and the utilization of the microscopic dynamics of the interaction between the agent and the sensor. We study the relationship between the measurement time window and the statistical error of the measurement data in the simplest case, when the output is the mean-square value of the stochastic signal. This situation is relevant at any practical case when the time window is finite, for example, when a sampling of the output of a fluctuation-enhanced array takes place; or a single sensor's activation (temperature, etc.) is stepped up; or a single sensor's output is monitored by sampling subsequently in different frequency windows. Our study provides a lower limit of the relative error versus data window size with different types of power density spectra: white noise, 1/f (flicker, pink) noise, and 1/f 2 (red) noise spectra.
Journal Paper - 2011 by CHIMAN KWAN
IEEE Trans. Nanotechnology, 2011
We survey and show our earlier results about three different ways of fluctuation-enhanced sensing... more We survey and show our earlier results about three different ways of fluctuation-enhanced sensing of bio agent, 1) the phage-based method for bacterium detection published earlier; 2) sensing and evaluating the odors of microbes; and 3) spectral and amplitude distribution analysis of noise in light scattering to identify spores based on their diffusion coefficient.
2011 IEEE Industry Applications Society Annual Meeting, 2011
In power distribution networks, impedance shortcircuit faults are hard to detect in their incipie... more In power distribution networks, impedance shortcircuit faults are hard to detect in their incipient, as fault currents may not be large enough to trip circuit breakers. In this paper, we summarize our research activities in short-circuit fault locating in underground power distribution networks. First, a simulation testbed was built. It can emulate power distribution networks with both bolted and impedance faults. Different impedances can be added to different branches. Power injection points, load nodes, and short-circuit fault locations can all be adjusted by users. Second, a hardware testbed corresponding to the simulation testbed was fabricated. Third, two novel fault locating algorithms (fault signature matching and sparsity recovery) were implemented. Results obtained from the simulation and hardware testbeds have excellent agreement. Our fault locating algorithms are validated by extensive numerical and experimental data. It is observed that, standard voltage measurements at a small number of preselected nodes are sufficient to locate the faults precisely; and hence, our fault locating scheme is of low cost. In addition, since our algorithms require only simple matrix calculations, location determination within a few cycles (< 50ms) is achievable.
Uploads
Journal Paper - 2017 by CHIMAN KWAN
Journal Paper - 2016 by CHIMAN KWAN
Journal Paper - 2015 by CHIMAN KWAN
Journal Paper - 2013 by CHIMAN KWAN
Journal Paper - 2012 by CHIMAN KWAN
Journal Paper - 2011 by CHIMAN KWAN