Complex-valued speckle effect and its suppression for high quality of phase unwrapping reconstruction in coherent digital holographic microscopy

In coherent digital holographic microscopy, speckle noise is incorporated into the hologram so that phase reconstruction may become worse in quality. Meanwhile, the previous speckle suppression algorithms are not satisfactory to solving this problem due to under- or over-filtering the image with a purely multiplicative or additive phase processing technique. In this paper, the complex-valued speckle effect on the phase reconstruction is first disclosed in theory by creating a multiplicative complex-valued model. A composite noise processing approach is subsequently proposed, which combines a revision of speckle reducing anisotropic diffusion algorithm and an improvement of dual-domain noise processing technique by developing a principal component analysis model for the image blocks to determine the true noise standard deviation in the algorithm for optimization of speckle suppression. The phase unwrapping algorithm with proposed speckle suppression processing is optimally combined to obtain better robustness and phase reconstruction quality of the image. The results are satisfactory. It verifies the validity of the proposed method especially for the objects with continuously-varied phases