A Zernike-moment-based non-local denoising filter for cryo-EM images

Jia Wang,Changcheng Yin

doi:10.1007/s11427-013-4467-3

Abstract

Cryo-electron microscopy (cryo-EM) plays an important role in determining the structure of proteins, viruses, and even the whole cell. It can capture dynamic structural changes of large protein complexes, which other methods such as X-ray crystallography and nuclear magnetic resonance analysis find difficult. The signal-to-noise ratio of cryo-EM images is low and the contrast is very weak, and therefore, the images are very noisy and require filtering. In this paper, a filtering method based on non-local means and Zernike moments is proposed. The method takes into account the rotational symmetry of some biological molecules to enhance the signal-to-noise ratio of cryo-EM images. The method may be useful in cryo-EM image processing such as the automatic selection of particles, orientation determination, and the building of initial models.

Highlights

Cryo-electron microscopy plays an important role in determining the structure of proteins, viruses, and even the whole cell
The method takes into account the rotational symmetry of some biological molecules to enhance the signal-to-noise ratio of Cryo-electron microscopy (cryo-EM) images
The method may be useful in cryo-EM image processing such as the automatic selection of particles, orientation determination, and the building of initial models

Summary

Introduction

Cryo-electron microscopy (cryo-EM) plays an important role in determining the structure of proteins, viruses, and even the whole cell. A filtering method based on non-local means and Zernike moments is proposed. The non-local means filter [4] is a new kind of spatial filter that works well in both detail preservation and noise removal, and it is capable of yielding high-quality denoising results Improvements of this method have been reported to work well in the processing of different kinds of images, such as fluorescent images of living cells [5] and Positron Emission Tomography images [6]. If the rotation symmetry is considered, the LANL method may be improved This can be achieved using Zernike moments to compute the similarity between two pixels in an image. We present a Zernike-moment-based non-local means filter for cryo-EM images and analyze the filtering effect.

Methods

Results

Conclusion