Enhancement of grayscale image display with amplitude Fourier holograms, employing a limited bandwidth phase

Abstract

An alternative method is proposed to generate a modified random phase that is able to concentrate the light around a given direction, produces well-contrasted Fourier amplitude holograms, reduces the quantity and the randomness of the speckle noise in the image, and decreases the amount of data necessary for the phase definition. This modified limited bandwidth random phase uses structured random phase patterns to control the object dispersion. The resulting hologram displays an image with structured speckle noise (SSN), exhibiting similar metrics as the iterative method for hologram generation. A filtering process eliminates the SSN; the speckle contrast in the final image is reduced from 0.66 to 0.07; and the peak SNR increases from 7.21 dB to 12.62 dB. This method enhances the fine details and grayscale tone perception in the final image.