Analysis of noise model of optical coherence tomography image in logarithmic domain

In order to analyze the speckle noise distribution model of optical coherence tomography (OCT) images before and after logarithm transformation and provide references for image de-noising and other image processing, theoretical distribution model of the speckle noise was deduced firstly and then was verified by experimental results. First of all, the statistical properties of the speckle noise before the logarithm transformation were analyzed. The distribution model of the speckle noise after logarithm transform was derived through the mathematical theory. Then, the smooth regions of cardiovascular OCT images were selected as the experimental data to obtain the histogram distribution of the speckle noise before and after the logarithm transformation. Finally, the experimental data were fitted by the theoretical distribution model and the evaluated data, such as R-square, root mean square error and X-square tests. The results prove that the noise distribution after logarithm transformation presents Fisher-Tippett distribution. The results are helpful for the de-noising on OCT images.