光学相干层析成像过程中产生的噪声恶化了其成像质量。提高图像的信噪比一直是光学相干层析系统研制中一个焦点问题。根据光学相干层析系统采集的原始图像的信号和噪声分布的特点, 对双变量收缩的小波去噪方法进行了改进, 增加噪声系数比较多的子带的死亡地带半径来去除图像的噪声。利用对比度噪声比率、信噪比和边缘保持参数等评价指标来评价图像的改善效果。结果表明该方法能有效地去除噪声并可保留光学相干层析原始图像的边缘特征。

Noise in optical coherence tomographic (OCT) imaging degrades the quality of images, so improving image’s signal-to-noise ratio (SNR) is a focal problem in the development of OCT system. According to the distribution characteristics of signal and image noise collected by OCT system, a wavelet denoising method with a bivariate shrinkage function is improved, by increasing the radius of deadzone in a subband which includes more noise coefficient, to reduce noise. Some estimation parameters, such as contrast-to-noise ratio (CNR), SNR and edge preservation parameter, are used to estimate the improved effect of the image. The results show that it can reduce noise effectively and preserve edge information.