Visual contrast enhancements of optical coherence tomography images using combined digital and image fusion methods.

摘要

Optical coherence tomography (OCT) is an interferometric, non-invasive and non contact imaging technique that images biological tissues at micrometer scale resolution. Images obtained from the OCT process are often noisy and of low visual contrast level. This thesis focuses on improving the visual contrast of OCT images using combined digital enhancement and image fusion methods. Noise in the image is removed by the Contra Harmonic filter. The image is, then, subjected to combined digital enhancement by High Boost Filter, Intensity Adjustment and Adaptive Histogram Equalization. In the combined digital enhancement process, several enhancement processes are applied sequentially to the original image, which results in better visual contrast. In the image fusion methods, images taken at different depths are fused together before enhancements. Two images are fused by Discrete Wavelet Transform Fusion method at 120 mum apart and the fused image is enhanced by combined digital enhancement process. This results in better visual contrast that is useful in medical analysis of the OCT images.