Sun Glint Removal from Water Area Image using Bidirectional Empirical Mode Decomposition

• Main Authors: Shih, Ling-Chien, 施伶蒨
• Other Authors: Shih,Tian-Yuan
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/54511089937041335884

碩士 === 國立交通大學 === 土木工程學系 === 100 === When taking aerial photography images on sea area at daytime, the sea surface reflection of solar radiation cause the sun glint. It will cause the loss of image information, even continuous images stitching. In this paper bring up the definition of sun glint, and use the radiation transfer analysis and image processing methods for testing. We readed images to get digital numbers, but we can’t transfer it to radiance.Even we use Cox and Munk (1954) Model and MODO to get the transmittance and solar radiance, we still can’t correct the radiance.There was no models of sea surface when shooting images,the transmittance we calculated can’t apply for every point of surface, it can’t be used to correct sun glint. For the uneven image colors and the loss of image information, using white balancing and dehazing for testing, the results found sun glint region increased significantly, increase the range and brightness exaggerated. If sun glint area can be regarded as the brightness characteristics and allowed images from RGB color space into HSV color space, the Value processed with Bidimensional Empirical Mode Decomposition(BEMD), and found that the region and characteristics of residual with sun glint of origin images are the same, and removed the residual. That results can found that BEMD really improve the sun glint. The Mean value, Root Mean Square Error (RMSE) , Peak Signal to Noise Ratio(PSNR), and Structural Similarity (SSIM), which are the statistical indicators calculated for results, and these indicators compared with the naked eyes, and finally make conclusions and suggestions.