Speckle noise reduction in coherent imaging systems via hybrid median-mean filter

Abstract

Images recorded by coherent imaging systems, including laser-based photography, digital holography (DH), and digital holographic microscopy (DHM), are severely distorted by speckle noise. We present a single-shot image processing method to reduce the speckle noise, coined hybrid median-mean filter (HM2F), which is based on the average of conventional median-filtered images with different kernel sizes. The synergic combination of the median filter and mean approach provides a denoised image with reduced speckle contrast while the spatial resolution is kept at up to 97% of the original value. The HM2F method is compared with the conventional median filter approach, the 3D block matching filter, the nonlocal means filter, the 2D windowed Fourier transform filter, and the Wiener filter using different speckle-distorted images to benchmark its performance. Based on the experimental results and the simplicity of the technique, HM2F is proposed as an effective denoising tool for reducing the speckle noise in laser-based photography, DH, and DHM.

Publication Title

Optical Engineering

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