Sea cucumbers usually live in an environment where lighting and visibility are generally not controllable,which cause the underwater image of sea cucumbers to be distorted,blurred,and severely attenuated.Therefore,the...Sea cucumbers usually live in an environment where lighting and visibility are generally not controllable,which cause the underwater image of sea cucumbers to be distorted,blurred,and severely attenuated.Therefore,the valuable information from such an image cannot be fully extracted for further processing.To solve the problems mentioned above and improve the quality of the underwater images of sea cucumbers,pre-processing of a sea cucumber image is attracting increasing interest.This paper presents a newmethod based on contrast limited adaptive histogram equalization and wavelet transform(CLAHE-WT)to enhance the sea cucumber image quality.CLAHE was used to process the underwater image for increasing contrast based on the Rayleigh distribution,and WTwas used for de-noising based on a soft threshold.Qualitative analysis indicated that the proposed method exhibited better performance in enhancing the quality and retaining the image details.For quantitative analysis,the test with 120 underwater images showed that for the proposed method,the mean square error(MSE),peak signal to noise ratio(PSNR),and entropy were 49.2098,13.3909,and 6.6815,respectively.The proposed method outperformed three established methods in enhancing the visual quality of sea cucumber underwater gray image.展开更多
Based on the sea ice digital videos and photos along the investigation route in the Second Chinese National Arctic Research Expedition (CHINARE) during July and September, 2003, collections of sea ice thickness and co...Based on the sea ice digital videos and photos along the investigation route in the Second Chinese National Arctic Research Expedition (CHINARE) during July and September, 2003, collections of sea ice thickness and concentration in the area of latitude range of 74.11°N - 79.56°N and longitude range of 144.17°W - 169.95°W are finished. This paper discusses the methods of obtaining ice/snow thicknesses from ship-side videos and ice concentrations from aerial photos, and illustrates the measures should be taken in analysis and in-situ investigation processes to improve the reliability of the parameters. The methods in this paper are somewhat universal and can be used in the research of Bohai Sea and Polar Regions sea ice.展开更多
On the basis of aerial photos of sea ice in the Second Chinese NationalArctic Research Expdition during July and September 2003 in the area of 74.11°～79.56°N and144.17°～169.95°W, image processing...On the basis of aerial photos of sea ice in the Second Chinese NationalArctic Research Expdition during July and September 2003 in the area of 74.11°～79.56°N and144.17°～169.95°W, image processing techniques are used to acquire some geometric parameters offloes, such as fractal dimension, roundness and mean caliper diameter. Latitudinal variation ofmorphology of arctic ice floes is then obtained, after comparing fractal dimension and roundnesswhich represent geometry of floe edge, the latter is found to show a more obvious tendency withlatitude but still not enough to describe floe abrasion. Then mean caliper diameter of ice floe isused as characteristic size to analyze floe size distribution, the result reveals that cumulativeprobabilities of floe sizes agree well with a power-law function, and distribution dimension isgenerally in the range of 1.05～1.25 and slightly increases as the latitude increases. Howeverslight curvatures are still observed in the plots of cumulative probabilities as in formerresearches, which can be attributed to both the limitation of sampling area and effect ofthermodynamic process.展开更多
The thermal front in the oceanic system is believed to have a significant effect on biological activity.During an era of climate change,changes in heat regulation between the atmosphere and oceanic interior can alter ...The thermal front in the oceanic system is believed to have a significant effect on biological activity.During an era of climate change,changes in heat regulation between the atmosphere and oceanic interior can alter the characteristics of this important feature.Using the simulation results of the 3D Regional Ocean Modelling System(ROMS),we identified the location of thermal fronts and determined their dynamic variability in the area between the southern Andaman Sea and northern Malacca Strait.The Single Image Edge Detection(SIED)algorithm was used to detect the thermal front from model-derived temperature.Results show that a thermal front occurred every year from 2002 to 2012 with the temperature gradient at the location of the front was 0.3°C/km.Compared to the years affected by El Ni?o and negative Indian Ocean Dipole(IOD),the normal years(e.g.,May 2003)show the presence of the thermal front at every selected depth(10,25,50,and 75 m),whereas El Ni?o and negative IOD during 2010 show the presence of the thermal front only at depth of 75 m due to greater warming,leading to the thermocline deepening and enhanced stratification.During May 2003,the thermal front was separated by cooler SST in the southern Andaman Sea and warmer SST in the northern Malacca Strait.The higher SST in the northern Malacca Strait was believed due to the besieged Malacca Strait,which trapped the heat and make it difficult to release while higher chlorophyll a in Malacca Strait is due to the freshwater conduit from nearby rivers(Klang,Langat,Perak,and Selangor).Furthermore,compared to the southern Andaman Sea,the chlorophyll a in the northern Malacca Strait is easier to reach the surface area due to the shallower thermocline,which allows nutrients in the area to reach the surface faster.展开更多
基金supported by the International Science&Technology Cooperation Program of China(2015DFA00090)Special Fund for Agro-scientific Research in the Public Interest(201203017).
文摘Sea cucumbers usually live in an environment where lighting and visibility are generally not controllable,which cause the underwater image of sea cucumbers to be distorted,blurred,and severely attenuated.Therefore,the valuable information from such an image cannot be fully extracted for further processing.To solve the problems mentioned above and improve the quality of the underwater images of sea cucumbers,pre-processing of a sea cucumber image is attracting increasing interest.This paper presents a newmethod based on contrast limited adaptive histogram equalization and wavelet transform(CLAHE-WT)to enhance the sea cucumber image quality.CLAHE was used to process the underwater image for increasing contrast based on the Rayleigh distribution,and WTwas used for de-noising based on a soft threshold.Qualitative analysis indicated that the proposed method exhibited better performance in enhancing the quality and retaining the image details.For quantitative analysis,the test with 120 underwater images showed that for the proposed method,the mean square error(MSE),peak signal to noise ratio(PSNR),and entropy were 49.2098,13.3909,and 6.6815,respectively.The proposed method outperformed three established methods in enhancing the visual quality of sea cucumber underwater gray image.
基金supported by the National Natural Science Foundation of China(40233032)China Social Commonweal Project(2003DEB5J057).
文摘Based on the sea ice digital videos and photos along the investigation route in the Second Chinese National Arctic Research Expedition (CHINARE) during July and September, 2003, collections of sea ice thickness and concentration in the area of latitude range of 74.11°N - 79.56°N and longitude range of 144.17°W - 169.95°W are finished. This paper discusses the methods of obtaining ice/snow thicknesses from ship-side videos and ice concentrations from aerial photos, and illustrates the measures should be taken in analysis and in-situ investigation processes to improve the reliability of the parameters. The methods in this paper are somewhat universal and can be used in the research of Bohai Sea and Polar Regions sea ice.
基金supported by the National Natural Science Foundation of China under contract Nos 40233032 and 40376006China Science and Technology Basement and Social Commonweal Special Project under contract No.2003DEB5J057.
文摘On the basis of aerial photos of sea ice in the Second Chinese NationalArctic Research Expdition during July and September 2003 in the area of 74.11°～79.56°N and144.17°～169.95°W, image processing techniques are used to acquire some geometric parameters offloes, such as fractal dimension, roundness and mean caliper diameter. Latitudinal variation ofmorphology of arctic ice floes is then obtained, after comparing fractal dimension and roundnesswhich represent geometry of floe edge, the latter is found to show a more obvious tendency withlatitude but still not enough to describe floe abrasion. Then mean caliper diameter of ice floe isused as characteristic size to analyze floe size distribution, the result reveals that cumulativeprobabilities of floe sizes agree well with a power-law function, and distribution dimension isgenerally in the range of 1.05～1.25 and slightly increases as the latitude increases. Howeverslight curvatures are still observed in the plots of cumulative probabilities as in formerresearches, which can be attributed to both the limitation of sampling area and effect ofthermodynamic process.
基金the Higher Education Ministry research grant,under the Long-Term Research Grant Scheme(No.LRGS/1/2020/UMT/01/1/2)the Universiti Malaysia Terengganu Scholarship(BUMT)。
文摘The thermal front in the oceanic system is believed to have a significant effect on biological activity.During an era of climate change,changes in heat regulation between the atmosphere and oceanic interior can alter the characteristics of this important feature.Using the simulation results of the 3D Regional Ocean Modelling System(ROMS),we identified the location of thermal fronts and determined their dynamic variability in the area between the southern Andaman Sea and northern Malacca Strait.The Single Image Edge Detection(SIED)algorithm was used to detect the thermal front from model-derived temperature.Results show that a thermal front occurred every year from 2002 to 2012 with the temperature gradient at the location of the front was 0.3°C/km.Compared to the years affected by El Ni?o and negative Indian Ocean Dipole(IOD),the normal years(e.g.,May 2003)show the presence of the thermal front at every selected depth(10,25,50,and 75 m),whereas El Ni?o and negative IOD during 2010 show the presence of the thermal front only at depth of 75 m due to greater warming,leading to the thermocline deepening and enhanced stratification.During May 2003,the thermal front was separated by cooler SST in the southern Andaman Sea and warmer SST in the northern Malacca Strait.The higher SST in the northern Malacca Strait was believed due to the besieged Malacca Strait,which trapped the heat and make it difficult to release while higher chlorophyll a in Malacca Strait is due to the freshwater conduit from nearby rivers(Klang,Langat,Perak,and Selangor).Furthermore,compared to the southern Andaman Sea,the chlorophyll a in the northern Malacca Strait is easier to reach the surface area due to the shallower thermocline,which allows nutrients in the area to reach the surface faster.
