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Segmentation and classification of high spatial resolution images based on Hölder exponents and variance

Geo-Spatial Information Science 2017年第1期20卷 39-45页

作者： debasish chakraborty Sourabh Singh Dibyendu Dutta Regional Remote Sensing Centre-East National Remote Sensing CentreISRONew TownKolkataIndia Department of Computer Science and Engineering SMITSikkimIndia

Pixel-based or texture-based classification technique individually does not yield an appropriate result in classifying the high spatial resolution remote sensing imagery since it comprises textured and non-textured *** this study,Hölder exponents(HE)and variance(VAR)are used together to transform the image for measuring texture.A threshold is derived to segment the transformed image into textured and non-textured ***,the original image is extracted into textured and non-textured regions using this segmented image ***,extracted textured region is classified using ISODATA classification algorithm considering HE,VAR,and intensity values of individual pixel of textured *** extracted non-textured region of the image is classified using ISODATA classification *** case of non-textured region,HE and VAR value of individual pixel is not considered for classification for significant textural variation is not found among different ***,the classified outputs of non-textured and textured regions that are generated independently are merged together to get the final classified *** 1 m PAN images are classified using the proposed algorithm,and the classification accuracy is more than 88%.

关键词： High-resolution image texture segmentation Hölder exponents variance contrast classification ISODATA

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Inversion of radiative transfer model for retrieval of wheat biophysical parameters from broadband reflectance measurements

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Information Processing in Agriculture 2016年第2期3卷 107-118页

作者： Vinay Kumar Sehgal debasish chakraborty Rabi Narayan Sahoo Division of Agricultural Physics Indian Agricultural Research InstituteNew Delhi 110012India

This study describes the retrieval of wheat biophysical variables of leaf chlorophyll(Cab),leaf area index(LAI),canopy chlorophyll(CCC),and leaf wetness(Cw)from broadband reflectance data corresponding to IRS LISS-3(Linear Imaging Self Scanner)sensor by inversion of PROSAIL5B canopy radiative transfer *** data of wheat crop,grown under different treatments,were measured by hand-held spectroradiometer and later integrated to LISS-3 reflectance using its band-wise relative spectral response *** inversion techniques were used and their performance was compared using different statistical parameters and target *** inversion techniques tried were:a look up table with best solution(LUT-I),a look up table with mean of best 10%solutions(LUT-II)and an artificial neural network(ANN).All the techniques could estimate the biophysical variables by capturing variability in their observed values,though accuracy of estimation varied among the three *** diagram clearly depicted the superiority of LUT-II over the other two approaches indicating that a mean of best 10%solutions is a better strategy while ANN was worst performer showing highest bias for all the *** all the three inversion techniques,the general order of retrieval accuracy was LAI>Cab>CCC>*** range of Cw was very narrow and none of the techniques could estimate variations in *** most of the cases,the parameters were underestimated by model *** best identified LUT-II technique was then applied to retrieve wheat LAI from IRS LISS-3 satellite image of 5-Feb-2012 in Sheopur *** comparison with ground observations showed that the RMSE of LAI retrieval was about 0.56,similar to that observed in ground *** findings of this study may help in refining the protocol for generating operational crop biophysical products from IRS LISS-3 or similar sensors.

关键词： PROSAIL Look up table Neural network Leaf area index Chlorophyll content Target diagram IRS LISS-3

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Elevated Vascular Endothelial Growth Factor Level in Association with Mean Platelet Volume Are Emerging Risk Factors for Vascular Complications in T2DM Patients

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Health 2019年第11期11卷 1542-1553页

作者： Priyanka Biswas Amit Kr. chakraborty Anumoy Mukherjee Baidyanath Pal debasish Maji Madhusnata De Department of Genetics Vivekananda Institute of Medical Sciences Ramakrishna Mission Seva Pratishthan Kolkata India Department of Pathology Murshidabad Medical College and Hospital Berhampore India Biological Anthropological Unit Indian Statistical Institute Kolkata India Department of Endocrinology Vivekananda Institute of Medical Sciences Ramakrishna Mission SevaPratishthan Kolkata India

Increasing evidence in both experimental and clinical studies suggests oxidative stress (OS) plays a major role in the pathogenesis of type 2 diabetes mellitus and its complications. In a physiological condition, appropriate levels of ROS, generated either in restricted amounts or transient fashion, are required to promote physiological angiogenesis and homeostatic maintenance of healthy vasculature. Uncontrolled continuous ROS production will ultimately contribute to pathology and cause tissue damage. One of the most important proangiogenic factors is vascular endothelial growth factor (VEGF) which plays a key role in diabetic endothelial dysfunction, which ultimately leads to pathogenesis of vascular complications. As VEGF is released by activated platelets, hence platelet activation could be the source of VEGF in plasma samples. Increased platelet activity is emphasized to play a role in the development of vascular complications in T2DM patients and platelet volume, a marker of the platelet function and activation, is measured as mean platelet volume (MPV). Therefore, we aimed to investigate the association between plasma VEGF levels and MPV levels that may lead to vascular complications. A case-control study of one hundred patients with T2DM (n = 100) and thirty control subjects (n = 30) were screened from different areas of West Bengal. All procedures were done with the informed consent of participants. Elevated VEGF level was found in T2DM patients (526.8 ± 34.3 pg/ml) compared to healthy controls (317.9 ± 12.9 pg/ml) which was statistically significant. T2DM patients had higher MPV (12.5 ± 0.2 fl) compared to controls (11.4 ± 0.2 fl). Thus the present study showed a significant association between VEGF level in plasma and MPV indicating the severity of vascular complications. Hence, in conclusion, it suggested that VEGF levels along with MPV are a reliable biomarker for evaluating the development and progression of vascular complications.

关键词： Oxidative Stress Vascular Endothelial Growth Factor Mean Platelet Volume Vascular Complications

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