The University of Hong Kong, Department of Electrical and Electronic Engineering, Pokfulam Road, Hong Kong, China.
J Biomed Opt. 2013 Sep;18(9):096002. doi: 10.1117/1.JBO.18.9.096002.
Visibility of optical coherence tomography (OCT) images can be severely degraded by speckle noise. A computationally efficient despeckling approach that strongly reduces the speckle noise is reported. It is based on discrete wavelet transform (DWT), but eliminates the conventional process of threshold estimation. By decomposing an image into different levels, a set of sub-band images are generated, where speckle noise is additive. These sub-band images can be compounded to suppress the additive speckle noise, as DWT coefficients resulting from speckle noise tend to be approximately decorrelated. The final despeckled image is reconstructed by taking the inverse wavelet transform of the new compounded sub-band images. The performance of speckle reduction and edge preservation is controlled by a single parameter: the level of wavelet decomposition. The proposed technique is applied to intravascular OCT imaging of porcine carotid arterial wall and ophthalmic OCT images. Results demonstrate the effectiveness of this technique for speckle noise reduction and simultaneous edge preservation. The presented method is fast and easy to implement and to improve the quality of OCT images.
光学相干断层扫描（OCT）图像的可见度可能会受到散斑噪声的严重影响。本文报道了一种计算效率高的去散斑方法，可以有效降低散斑噪声。该方法基于离散小波变换（DWT），但消除了传统的阈值估计过程。通过将图像分解为不同的层次，可以生成一组子带图像，其中散斑噪声是附加的。这些子带图像可以进行复合，以抑制附加的散斑噪声，因为来自散斑噪声的 DWT 系数往往是近似不相关的。通过对新复合子带图像进行逆小波变换，重建最终的去散斑图像。通过单个参数来控制去噪和边缘保持的性能：小波分解的层次。该技术应用于猪颈动脉壁的血管内 OCT 成像和眼科 OCT 图像。结果表明，该技术在降低散斑噪声和同时保持边缘方面具有有效性。所提出的方法快速、易于实现，可以提高 OCT 图像的质量。
