Some unique features and highlights of the methods offered as part as the ASPIRE platform: 

1. Automatic Particle Picking: The APPLE-Picker is an automatic, training-free, and template-free procedure for particle picking, currently available as a standalone toolbox. 
2. 2-D Classification and Averaging: classification of images with similar viewing directions, in-plane registration and averaging to improve their signal-to-noise ratio (SNR).
3. Orientation Estimation: assigning orientations to the class averages based on their mutual common-lines.
4. 3-D Covariance Estimation: a standalone useful tool for analysis conformational variability.  

Please refer to the relevant sections and the publication list in order to learn more about the algorithms.