Computer generation of binary Fresnel holography

Abstract

Binarization of Fresnel holograms by direct thresholding based on the polarity of the fringe pattern is studied. It is found that if the hologram is binarized (i.e., for black and white hologram pixels) in this manner, only the edges of the object are preserved in the reconstructed image. To alleviate the errors caused by binarization, the use of error diffusion has been routinely employed. However, the reconstructed image using such standard technique is heavily contaminated with random noise. In this paper, we propose a novel noniterative method for generating Fresnel holograms that are suitable for binarization. Our method is capable of preserving good visual quality on the reconstructed images.

Complex Fresnel hologram display using a single SLM

“…But, in Section 4, we use two binary holograms for experimental demonstration because binary holograms can be produced swiftly with printers. In addition, with binary holograms, we could enhance the storage capacity of digital holograms and facilitate more efficient transmission of holograms [30]. To accomplish the binarization process, we first add a random phase to the object pattern, and then calculate the corresponding diffraction field.…”

“…To accomplish the binarization process, we first add a random phase to the object pattern, and then calculate the corresponding diffraction field. The binary holograms are obtained by binarizing the real and the imaginary parts of H cp by the sign binarization method [30], i.e.,…”

“…The random phase can help expand the spectrum of the object light and reduces the edge effect caused by binarization [30]. The two binary holograms B r and B i are shown in Figs.…”

Enhanced method for the generation of binary Fresnel holograms based on grid-cross downsampling

“…An alternative method has been reported in Ref. [20] with the integration of grid line downsampling and sign thresholding, which provides a better preservation of the shaded regions in the reconstructed image and with less amount of noise contamination. Despite the success, the shaded regions are filled with a texture of uniformly spaced holes that are rather prominent in the reconstructed image.…”

“…We then describe the pros and cons of the method in Ref. [20], which is developed to reduce the artifacts caused by sign thresholding. Our proposed scheme and its evaluation are presented.…”