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Contrast between the wavelet transform with coefficients selection method and the traditional frequency domain filtering method for digital hologram reconstruction

The wavelet transform with coefficients selection method and the one of traditional frequency domain filtering methods named Gaussian high-pass filter method are used for the reconstruction of the digital holograms in this paper. In order to eliminate the speckle noise near the filtered zero-order diffraction spots more effectively, the high and low frequency coefficients in the wavelet transform were adjusted. A holographic experimental system based on Michelson interferometer was set up and digital off-axis holograms were recorded. By adopting the Robert gradient method in Iconology, the reconstructed results both by the wavelet transform with coefficients selection method and the traditional Gaussian high-pass filter method were compared. The larger the gradient magnitude value (G) is, the more information the image contains, and the image is clearer. The G values of the reconstructed images got by wavelet transform with coefficients selection method and the traditional Gaussian filtering method are 1099891 and 1042562, respectively. The results validated that applying the wavelet transform with coefficients selection method for digital hologram reconstruction can more effectively eliminate zero-order diffraction image and improve the SNR and quality of reconstructed image than applying the traditional Gaussian high-pass filter method.