Reconstruction of noisy images via stochastic resonance in nematic liquid crystals

Abstract

We employ nematic liquid crystals as the nonlinear medium to recover noisy images via stochastic resonance, in which nonlinear coupling allows signals to grow at the expense of noise. The process is theoretically analyzed and the cross-correlation is numerically calculated. It is found that the quality of output images is affected by the input noise intensity, the applied voltage and the correlation length of noise light. Noise-hidden images can be effectively recovered by optimizing these parameters. The results suggest that nematic liquid crystals can be used for reconstruction of noisy images via stochastic resonance based on modulation instability with molecule reorientation nonlinearity.

On some applications of vibrational resonance on noisy image perception: the role of the perturbation parameters

“…Very recently, another way to take benefit of SR in image processing by adjusting the system parameters has been addressed in a nonlinear optical system containing photorefractive or nematic liquid crystals [32–35]. During this process of image enhancement, which uses modulation instability, the nonlinear coefficient of the crystal is controlled by an external voltage.…”

“…Lastly the performance of the detector is quantified by a measurement of similarity between the initial image I and the black and white detected image T . More precisely, we use the cross-covariance which constitutes a fairly appropriate measurement of similarity between two images [35,43,56]. This cross-covariance between image I and T is defined by CI,T=falsefalse⟨false(I−falsefalse⟨Ifalsefalse⟩false)false(T−falsefalse⟨Tfalsefalse⟩false)falsefalse⟩falsefalse⟨false(I−falsefalse⟨Ifalsefalse⟩false)2falsefalse⟩falsefalse⟨false(T−falsefalse⟨Tfalsefalse⟩false)2falsefalse⟩, where 〈.〉 corresponds to an average over the whole image, that is an average across all the image pixels.…”

Experimental focusing shocklike dynamics in a nonlocal optical stochastic Kerr medium

“…3(a-c) do not emphasize them since their transverse location and periodicity are wandering with time [34] and are washed out by the averaging process. Further study would be necessary to identify these short wavelength instabilities with noise sustained modulational instability [14] or other stochastic resonance behavior [38]. Although no focusing dispersive dam break flows are experimentally observed in our stochastic nonlinear medium, shock-like dynamics is still observable.…”

Online Signal Denoising Using Adaptive Stochastic Resonance in Parallel Array and Its Application to Acoustic Emission Signals

“…As a result, the output power spectral density corresponding to the periodic excitation frequency may be greatly increased and exhibit a peak when SR occurs. Due to this constructive role of noise when SR is activated, SR has been explored in a variety of contexts, such as biomedical systems [18,19], image processing [20,21], and fault diagnosis in mechanical systems [22][23][24][25][26][27][28][29][30].…”