Granulometric Analysis of Speckles for Polarization-Difference Imaging in Turbid Media
Z. F. Li, H. Li, W. M. Xie, and L. L. Fan
Polarization gating techniques have been previously applied to image the absorption of objects embedded in an optically scattering medium; however, speckle noise existed in the polarization gating imaging in the case of coherent illumination. In this paper we employed a morphological opening operation with a disc-shaped structuring element to suppress the speckle coarse grains, improving the quality of polarization-difference images. Furthermore, the successive opening operations with a family of structuring elements of different sizes were used to estimate the average granulometric size of speckles. Finally, it was experimentally demonstrated that the average granulometric size of speckles is approximately in proportion to the background scattering coefficient of turbid media.
Keywords: Granulometric analysis, speckle, polarization-difference, scattering coefficient, turbid media