【摘要】：圖像,是人類獲得信息最直接、最常見的資源。但由于圖像的獲取與傳輸過程易受到外界因素的影響,往往使得圖像不甚理想,給后續(xù)的處理造成一定不便,因此,圖像增強在圖像預(yù)處理階段是一個關(guān)鍵環(huán)節(jié)。傳統(tǒng)的圖像增強主要是在空間域和變換域內(nèi)處理。模糊算法是一種介于兩者之間的方法,即將圖像像素映射到模糊域,在模糊域中對相關(guān)系數(shù)做非線性處理來增強圖像的對比度。本文深入系統(tǒng)地研究了基于非下采樣輪廓波與剪切波的圖像增強算法并結(jié)合模糊對比度與多尺度Retinex思想,做出的主要工作如下:1、提出了一種基于NSCT和改進的模糊對比度的圖像增強方法。首先對圖像進行NSCT變換,其次對低頻子帶系數(shù)采用線性增強的方式來拉伸圖像的對比度,用改進的自適應(yīng)閾值函數(shù)來處理高頻系數(shù),濾除噪聲的影響,最后利用改進的模糊對比度算子來增強圖像的邊緣和紋理,仿真結(jié)果表明,相比于其它傳統(tǒng)方法或Pal_King的改進算法,該算法能夠明顯改善圖像的視覺效果并突出圖像的細節(jié)信息,且抗噪性能良好。2、提出了一種基于Shearlet變換和多尺度Retinex結(jié)合的遙感圖像增強方法。首先,用多尺度Retinex來調(diào)整分解后的剪切波的低頻分量,去除照射光對圖像的影響,其次,用閾值函數(shù)來消除剪切波不同尺度和方向上的高頻分量中的噪聲。最后,對重構(gòu)圖像進行模糊對比度增強,來提升圖像的全局對比度。實驗結(jié)果表明,本文提出的算法在改善光照條件對遙感圖像的影響以及豐富圖像紋理細節(jié)方面的有效性。
[Abstract]:Image is the most direct and common resource for human to obtain information. However, the process of image acquisition and transmission is easy to be affected by external factors, which often makes the image not ideal, causing some inconvenience to the subsequent processing. Therefore, image enhancement is a key step in the image preprocessing stage. Traditional image enhancement is mainly processed in spatial domain and transform domain. Fuzzy algorithm is a kind of method between them, which maps image pixels to fuzzy domain, and performs nonlinear processing of correlation coefficient in fuzzy domain to enhance the contrast of image. In this paper, the image enhancement algorithm based on non-downsampling contour wave and shear wave is studied in detail and combined with the idea of fuzzy contrast and multi-scale Retinex. The main work is as follows: 1. An image enhancement method based on NSCT and improved fuzzy contrast is proposed. Firstly, the image is transformed by NSCT, then the low frequency subband coefficient is linearly enhanced to stretch the contrast of the image, and the improved adaptive threshold function is used to deal with the high frequency coefficient to filter out the influence of noise. Finally, the improved fuzzy contrast operator is used to enhance the edge and texture of the image. The simulation results show that compared with other traditional methods or Pal_King 's improved algorithm, the algorithm can obviously improve the visual effect of the image and highlight the details of the image. A method of remote sensing image enhancement based on Shearlet transform and multi-scale Retinex is proposed. Firstly, multiscale Retinex is used to adjust the low-frequency component of the shearing wave after decomposition to remove the influence of the irradiated light on the image. Secondly, the threshold function is used to eliminate the noise in the high-frequency components of the shearing wave in different scales and directions. Finally, the global contrast of reconstructed image is enhanced by fuzzy contrast enhancement. Experimental results show that the proposed algorithm is effective in improving the influence of illumination conditions on remote sensing images and enriching the texture details of images.
【學(xué)位授予單位】：新疆大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TP751

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本文編號：2256238