Improved wavelet hierarchical threshold filter method for optical coherence tomography image de-noising

• Published in: Journal of innovative optical health science Vol. 11; no. 3; pp. 1850012-1 - 1850012-11
• Main Authors: Cao, Jing, Wang, Pinghe, Wu, Bo, Shi, Guohua, Zhang, Yan, Li, Xiqi, Zhang, Yudong, Liu, Yong
• Format: Journal Article
• Language: English
• Published: World Scientific Publishing Company 01.05.2018; World Scientific Publishing
• Subjects: Optical coherence tomography; speckle; wavelets; speckle; Optical coherence tomography; wavelets
• ISSN: 1793-5458; 1793-7205
• DOI: 10.1142/S1793545818500128

According to the speckle feature in Optical coherence tomography (OCT), images with speckle indicate not only noise but also signals, an improved wavelet hierarchical threshold filter (IWHTF) method is proposed. At first, a modified hierarchical threshold-selected algorithm is used to prevent signals from being removed by assessing suitable thresholds for different noise levels. Then, an improved wavelet threshold function based on two traditional threshold functions is proposed to trade-off between speckle removing and sharpness degradation. The de-noising results of an OCT finger skin image shows that the IWHTF method obtains better objective evaluation metrics and visual image quality improvement. When α = 0 . 2 , β = 5 . 0 and K = 1 . 2 , the improved method can achieve 9.58 dB improvement in signal-to-noise ratio, with sharpness degraded by 3.81%.