Histogram equalization is a traditional algorithm improving the image contrast,but it comes at the cost of mean brightness shift and details loss.In order to solve these problems,a novel approach to processing foregro...Histogram equalization is a traditional algorithm improving the image contrast,but it comes at the cost of mean brightness shift and details loss.In order to solve these problems,a novel approach to processing foreground pixels and background pixels independently is proposed and investigated.Since details are mainly contained in the foreground,the weighted coupling of histogram equalization and Laplace transform were adopted to balance contrast enhancement and details preservation.The weighting factors of image foreground and background were determined by the amount of their respective information.The proposed method was conducted to images acquired from CVG⁃UGR and US⁃SIPI image databases and then compared with other methods such as clipping histogram spikes,histogram addition,and non⁃linear transformation to verify its validity.Results show that the proposed algorithm can effectively enhance the contrast without introducing distortions,and preserve the mean brightness and details well at the same time.展开更多
In this paper, experiments of both the model turbine(1 k W) and the full scale(10 k W) turbine are carried out in a towing tank and a basin, respectively, and the test of the full scale turbine on the sea is conducted...In this paper, experiments of both the model turbine(1 k W) and the full scale(10 k W) turbine are carried out in a towing tank and a basin, respectively, and the test of the full scale turbine on the sea is conducted. By comparison between the model turbine(D= 0.7 m) and the full scale turbine(D= 2.0 m), it is shown that the maximum power coefficient increases with the increase of the diameter of the turbine. The test results on the sea are used to study the hydrodynamic performances of the horizontal axis turbine, and provide a basis for the design. Experimental results can validate the accuracy of the numerical simulation results.展开更多
基金Sponsored by the National Key R&D Program of China(Grant No.2018YFB1308700)the Research and Development Project of Key Core Technology and Common Technology in Shanxi Province(Grant Nos.2020XXX001,2020XXX009)。
文摘Histogram equalization is a traditional algorithm improving the image contrast,but it comes at the cost of mean brightness shift and details loss.In order to solve these problems,a novel approach to processing foreground pixels and background pixels independently is proposed and investigated.Since details are mainly contained in the foreground,the weighted coupling of histogram equalization and Laplace transform were adopted to balance contrast enhancement and details preservation.The weighting factors of image foreground and background were determined by the amount of their respective information.The proposed method was conducted to images acquired from CVG⁃UGR and US⁃SIPI image databases and then compared with other methods such as clipping histogram spikes,histogram addition,and non⁃linear transformation to verify its validity.Results show that the proposed algorithm can effectively enhance the contrast without introducing distortions,and preserve the mean brightness and details well at the same time.
基金Project supported by the National Natural Science Foun-dation of China(Grant Nos.51409057,51579055)the Resea-rch Fund for the Doctoral Program of Higher Education of China(Grant No.20132304110009)the Natural Science Foundation of Heilongjiang Province(Grant No.E2015048)
文摘In this paper, experiments of both the model turbine(1 k W) and the full scale(10 k W) turbine are carried out in a towing tank and a basin, respectively, and the test of the full scale turbine on the sea is conducted. By comparison between the model turbine(D= 0.7 m) and the full scale turbine(D= 2.0 m), it is shown that the maximum power coefficient increases with the increase of the diameter of the turbine. The test results on the sea are used to study the hydrodynamic performances of the horizontal axis turbine, and provide a basis for the design. Experimental results can validate the accuracy of the numerical simulation results.
