基于Retinex方法的無人機影像陰影去除應用研究
發(fā)布時間：2018-12-29 15:36
【摘要】：由于光照、地形起伏等原因,無人機航測獲取的影像中會出現(xiàn)陰影,使得影像對比度降低、地表信息模糊,降低了影像質(zhì)量同時也降低了 DOM質(zhì)量和目視解譯的準確度。為了有效恢復無人機航測影像中陰影遮蔽下的重要地表信息,論文分析國內(nèi)外關于航空影像陰影消除研究進展的基礎上,以隴南山區(qū)土地確權項目中獲取的存在陰影的無人機航測影像為數(shù)據(jù)源,選取10幅影像作為代表數(shù)據(jù)并基于實驗區(qū)影像中陰影的性質(zhì)和特點,利用傳統(tǒng)處理方法和Retinex方法對存在陰影的影像進行處理并進行對比分析研究,具體的研究結(jié)論如下:(1)利用代數(shù)運算、直方圖均衡化、同態(tài)濾波、勻光勻色等傳統(tǒng)圖像增強方法對存在陰影的影像進行處理,結(jié)合主觀效果以及標準差、信息熵、平均梯度影像質(zhì)量指標統(tǒng)計值對實驗結(jié)果進行綜合對比評價。結(jié)果表明:相對于原始影像,利用傳統(tǒng)方法處理影像會使影像質(zhì)量指標值有所增加,陰影區(qū)域地表信息有所恢復。(2)利用基于RGB色彩空間下的Retinex算法對存在陰影的影像進行處理,具體實現(xiàn)單尺度(SSR)、多尺度(MSR)和帶顏色恢復因子的Retinex算法(MSRCR)并進行實驗,通過對高斯模糊尺度參數(shù)的不同取值的處理結(jié)果進行對比分析,探究出相對合理的取值。結(jié)果表明:將MSRCR算法應用于無人機影像的陰影去除,雖然處理后的部分影像有一定的色彩偏離,但是在處理效果明顯性、細節(jié)恢復程度等方面的效果較為顯著,同時較原始影像,統(tǒng)計其影像質(zhì)量指標平均值,平均梯度、標準差、信息熵值分別提高了 4.5倍、1.5倍、0.2倍。(3)針對RGB色彩空間下的Retinex算法應用中出現(xiàn)色彩偏離的問題,利用基于HSV色彩空間下的Retinex算法對存在陰影的影像進行處理,并改進算法中的像素值量化方式,最后通過特征匹配實驗驗證算法可行性。結(jié)合主觀效果和影像質(zhì)量評價指標進行綜合評價,結(jié)果表明:一定程度的解決了色彩偏離的問題,有效恢復了陰影遮蔽下的地表信息,同時較原始影像,統(tǒng)計其影像質(zhì)量指標平均值,平均梯度、標準差、信息熵值分別提高了 16倍、3.4倍、0.3倍。通過上述的研究,表明利用Retinex方法可以有效恢復陰影遮蔽下的地表信息,該方法應用于無人機影像的陰影去除是可行的。
[Abstract]:Because of illumination, terrain fluctuation and so on, shadow will appear in the images obtained by UAV aerial survey, which makes image contrast lower, surface information blurred, image quality reduced and DOM quality and visual interpretation accuracy reduced. In order to effectively restore the important surface information of aerial vehicle aerial survey image under shadow shade, this paper analyzes the research progress of shadow elimination of aerial image at home and abroad. Taking the aerial vehicle images with shadows obtained from the land certification project in Longnan mountainous area as the data source, 10 images are selected as the representative data and based on the nature and characteristics of the shadows in the images of the experimental area. The traditional processing method and Retinex method are used to process the shadow images and the results are as follows: (1) using algebraic operation, histogram equalization, homomorphic filtering, Traditional image enhancement methods such as uniform light and uniform color are used to process shaded images. The experimental results are compared and evaluated comprehensively with subjective effects, standard deviation, information entropy and statistical value of average gradient image quality index. The results show that compared with the original image, the image quality index will be increased by using the traditional method to process the image. (2) using Retinex algorithm based on RGB color space to process shadow images, and realizing single-scale (SSR),. (2) the surface information of shadow region is recovered. (2) the Retinex algorithm based on RGB color space is used to process shadow images. Multi-scale (MSR) and Retinex algorithm (MSRCR) with color recovery factor are experimented. By comparing and analyzing the processing results of Gao Si's fuzzy scale parameters, a relatively reasonable value is found out. The results show that the MSRCR algorithm is applied to the shadow removal of UAV images, although some of the processed images have color deviation, but the processing effect is obvious, the degree of detail recovery and so on. At the same time, compared with the original image, the average image quality index, the average gradient, the standard deviation and the information entropy were increased by 4.5 times, 1.5 times, respectively. (3) aiming at the problem of color deviation in the application of Retinex algorithm in RGB color space, the Retinex algorithm based on HSV color space is used to process the shaded image, and the pixel quantization method in the algorithm is improved. Finally, the feasibility of the algorithm is verified by feature matching experiment. Combined with subjective effect and image quality evaluation index, the results show that: the problem of color deviation is solved to a certain extent, the surface information under shadow is recovered effectively, and the original image is more effective than the original image. The average image quality index, average gradient, standard deviation and information entropy were increased by 16 times, 3.4 times and 0.3 times respectively. Through the above research, it is shown that the Retinex method can effectively restore the surface information under shadow shading, and it is feasible to apply this method to the shadow removal of UAV images.
【學位授予單位】：西安科技大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TP391.41
本文編號：2395008
[Abstract]:Because of illumination, terrain fluctuation and so on, shadow will appear in the images obtained by UAV aerial survey, which makes image contrast lower, surface information blurred, image quality reduced and DOM quality and visual interpretation accuracy reduced. In order to effectively restore the important surface information of aerial vehicle aerial survey image under shadow shade, this paper analyzes the research progress of shadow elimination of aerial image at home and abroad. Taking the aerial vehicle images with shadows obtained from the land certification project in Longnan mountainous area as the data source, 10 images are selected as the representative data and based on the nature and characteristics of the shadows in the images of the experimental area. The traditional processing method and Retinex method are used to process the shadow images and the results are as follows: (1) using algebraic operation, histogram equalization, homomorphic filtering, Traditional image enhancement methods such as uniform light and uniform color are used to process shaded images. The experimental results are compared and evaluated comprehensively with subjective effects, standard deviation, information entropy and statistical value of average gradient image quality index. The results show that compared with the original image, the image quality index will be increased by using the traditional method to process the image. (2) using Retinex algorithm based on RGB color space to process shadow images, and realizing single-scale (SSR),. (2) the surface information of shadow region is recovered. (2) the Retinex algorithm based on RGB color space is used to process shadow images. Multi-scale (MSR) and Retinex algorithm (MSRCR) with color recovery factor are experimented. By comparing and analyzing the processing results of Gao Si's fuzzy scale parameters, a relatively reasonable value is found out. The results show that the MSRCR algorithm is applied to the shadow removal of UAV images, although some of the processed images have color deviation, but the processing effect is obvious, the degree of detail recovery and so on. At the same time, compared with the original image, the average image quality index, the average gradient, the standard deviation and the information entropy were increased by 4.5 times, 1.5 times, respectively. (3) aiming at the problem of color deviation in the application of Retinex algorithm in RGB color space, the Retinex algorithm based on HSV color space is used to process the shaded image, and the pixel quantization method in the algorithm is improved. Finally, the feasibility of the algorithm is verified by feature matching experiment. Combined with subjective effect and image quality evaluation index, the results show that: the problem of color deviation is solved to a certain extent, the surface information under shadow is recovered effectively, and the original image is more effective than the original image. The average image quality index, average gradient, standard deviation and information entropy were increased by 16 times, 3.4 times and 0.3 times respectively. Through the above research, it is shown that the Retinex method can effectively restore the surface information under shadow shading, and it is feasible to apply this method to the shadow removal of UAV images.
【學位授予單位】：西安科技大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TP391.41
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