光学相干层析技术的图像信息处理毕业.docVIP

毕业设计论文 光学相干层析技术的图像信息处理 【摘要】光学相干层析技术(Optical Coherence Tomography，简称OCT)是近年来继共焦扫描显微镜之后发展起来的光学成像技术，它利用弱相干光干涉仪的基本原理，检测生物组织不同深度层面对弱相干光的背向散射信号，通过扫描可得到生物组织的二维或三维图像。 由于OCT系统探测方法的特性以及被探测生物组织本身的高散射性，使得OCT图像存在各种噪声以及对比度低等特点，而OCT检测最终是通过图像信息进行诊断，因此提高OCT的成像质量非常重要。本文主要对OCT图像处理做研究，具有实际的应用价值。 本论文在现有实验室OCT系统的基础上，从图像处理的角度，结合国内外研究现状，讨论了OCT技术的基本原理和图像处理技术，从图像的噪声着手，研究了减小图像噪声的算法。 小波变换在图像去噪中具有很好的效果，随着近几年的发展，双树复小波被广泛的应用于图像去噪。双树复小波具有移不变性、多维取向、更小的冗余度，可以保持图像的相位信息不受损坏。本论文讨论了双树复小波变换，并利用此算法消除噪声，大大改善了图像的质量，可以基本满足对OCT图像初步分析判断。但是此算法不能有效的保护图像的边缘特征，需要进一步改进。 【关键词】光学相干层析技术；图像处理；去除噪声；双树复小波变换 The Image Processing Techniques in Optical Coherence Tomography Abstract: Optical Coherence Tomography is a new developing optical image technique following the confocal scanning microscopy. It uses weak coherent basic principle of the interferometer to detect the feeble coherent light back-scattered from the different depths of biological tissue, and then the two or three-dimensional tomographic image can be obtained by the scanning. Owing to the weak inherent nature of the imaging system and the detection method, OCT system suffers from different noises which degrade the quality of the images. The OCT diagnosis is finally realized from the image information, therefore, there is a great significance in improving the quality of the image. Based on the experimental OCT system in our laboratory, the OCT image processing techniques are discussed in the thesis. With the discussion of the available image processing techniques and theories, the noise reduction and contrast enhancement methods have been proposed. Wavelet transform has a good effect on image denoising, with the development in recent years, double-tree complex wavelet transform(DTCWT) is widely used in image denoising. Double-tree complex wavelet transform possesses shift invariant, multi-dimensional approach, smaller redundancy and phase information preserving without image damage. The principle of the DTCWT algorithm is discussed and the validity of the