To get a current list of Comaparators, run e2help.py cmp or for more detailed information e2help.py cmp -v 2.
The most commonly used comparators and options are:
- ccc - simple cross correlation coefficient (dot product). Causes orientation bias for some particles, but generally good for initial coarse alignments.
- frc:snrweight=1:zeromask=1 - Integrated Fourier ring correlation coefficient, in this case with SSNR weighting and noise masking. This is the standard for the highest resolution reconstructions. If used without snrweight=1, it is important to set a good maxres= value instead.
- phase:snrweight=1:zeromask=1 - Similar to frc, but uses mean phase error instead.