Classifying structural variability in noisy projections of biological macromolecules is a central problem in Cryo-EM. In this work, we build on a previous method for estimating the covariance matrix of the three-dimensional structure present in the molecules being imaged. Our proposed method allows for incorporation of contrast transfer function and non-uniform distribution of viewing angles, making it more suitable for real-world data. We evaluate its performance on a synthetic dataset and an experimental dataset obtained by imaging a 70S ribosome complex.
@article{arxiv.1412.0985,
title = {Covariance estimation using conjugate gradient for 3D classification in Cryo-EM},
author = {Joakim Andén and Eugene Katsevich and Amit Singer},
journal= {arXiv preprint arXiv:1412.0985},
year = {2015}
}