An efficient approach was proposed for discriminating shadows from moving objects. In the background subtraction stage, moving objects were extracted. Then, the initial classification for moving shadow pixels and fore...An efficient approach was proposed for discriminating shadows from moving objects. In the background subtraction stage, moving objects were extracted. Then, the initial classification for moving shadow pixels and foreground object pixels was performed by using color invariant features. In the shadow model learning stage, instead of a single Gaussian distribution, it was assumed that the density function computed on the values of chromaticity difference or bright difference, can be modeled as a mixture of Gaussian consisting of two density functions. Meanwhile, the Gaussian parameter estimation was performed by using EM algorithm. The estimates were used to obtain shadow mask according to two constraints. Finally, experiments were carried out. The visual experiment results confirm the effectiveness of proposed method. Quantitative results in terms of the shadow detection rate and the shadow discrimination rate(the maximum values are 85.79% and 97.56%, respectively) show that the proposed approach achieves a satisfying result with post-processing step.展开更多
With the non-ionizing,non-invasive,high penetration,high resolution and spectral fingerprinting features of terahertz(THz)wave,THz spectroscopy has great potential for the qualitative and quantitative identification o...With the non-ionizing,non-invasive,high penetration,high resolution and spectral fingerprinting features of terahertz(THz)wave,THz spectroscopy has great potential for the qualitative and quantitative identification of key substances in biomedical field,such as the early diagnosis of cancer,the accurate boundary determination of pathological tissue and non-destructive detection of superficial tissue.However,biological samples usually contain various of substances(such as water,proteins,fat and fiber),resulting in the signal-to-noise ratio(SNR)for the absorption peaks of target substances are very small and then the target substances are hard to be identified.Here,we present recent works for the SNR improvement of THz signal.These works include the usage of attenuated total reflection(ATR)spectroscopy,the fabrication of sample-sensitive metamaterials,the utilization of different agents(including contrast agents,optical clearing agents and aptamers),the application of reconstruction algorithms and the optimization of THz spectroscopy system.These methods have been proven to be effective theoretically,but only few of them have been applied into actual usage.We also analyze the reasons and summarize the advantages and disadvantages of each method.At last,we present the prospective application of THz spectroscopy in biomedical field.展开更多
基金Project(50805023)supported by the National Natural Science Foundation of ChinaProject(BA2010093)supported by the Special Fund of Jiangsu Province for the Transformation of Scientific and Technological Achievements,ChinaProject(2008144)supported by the Hexa-type Elites Peak Program of Jiangsu Province,China
文摘An efficient approach was proposed for discriminating shadows from moving objects. In the background subtraction stage, moving objects were extracted. Then, the initial classification for moving shadow pixels and foreground object pixels was performed by using color invariant features. In the shadow model learning stage, instead of a single Gaussian distribution, it was assumed that the density function computed on the values of chromaticity difference or bright difference, can be modeled as a mixture of Gaussian consisting of two density functions. Meanwhile, the Gaussian parameter estimation was performed by using EM algorithm. The estimates were used to obtain shadow mask according to two constraints. Finally, experiments were carried out. The visual experiment results confirm the effectiveness of proposed method. Quantitative results in terms of the shadow detection rate and the shadow discrimination rate(the maximum values are 85.79% and 97.56%, respectively) show that the proposed approach achieves a satisfying result with post-processing step.
基金National Major Project of Scientific Instrument and Equipment Development(2017YFF0106300)National Natural Science Foundation of China(61922059,61771314,61722111,81961138014)+3 种基金Shanghai Rising-Star Program(17QA1402500)the 111 Project(D18014)the International Joint Lab Program supported by Science and Technology Commission Shanghai Municipality(17590750300)the Key project supported by Science and Technology Commission Shanghai Municipality(YDZX20193100004960).
文摘With the non-ionizing,non-invasive,high penetration,high resolution and spectral fingerprinting features of terahertz(THz)wave,THz spectroscopy has great potential for the qualitative and quantitative identification of key substances in biomedical field,such as the early diagnosis of cancer,the accurate boundary determination of pathological tissue and non-destructive detection of superficial tissue.However,biological samples usually contain various of substances(such as water,proteins,fat and fiber),resulting in the signal-to-noise ratio(SNR)for the absorption peaks of target substances are very small and then the target substances are hard to be identified.Here,we present recent works for the SNR improvement of THz signal.These works include the usage of attenuated total reflection(ATR)spectroscopy,the fabrication of sample-sensitive metamaterials,the utilization of different agents(including contrast agents,optical clearing agents and aptamers),the application of reconstruction algorithms and the optimization of THz spectroscopy system.These methods have been proven to be effective theoretically,but only few of them have been applied into actual usage.We also analyze the reasons and summarize the advantages and disadvantages of each method.At last,we present the prospective application of THz spectroscopy in biomedical field.
