EMAN
Refine 3d Model
Determine CTF parameters
Once the particles are boxed we may use ctfit
to determine the ctf parameters. Knowing the ctf parameters is necessary
in order to classify the particles into
classes and to align the particles
within these classes. The ctf parameters include the microscope parameters
(spherical aberration coefficient, the defocus, as well as temperature
factor) as well as the parameters that describe the effects of the noise
(for which there are 5). This information is written into the headers for
the particle files and are read by the classification and alignment programs.
At this point also, the phases are flipped (see ctfit). So besides the
new header information, the particles themselves are modified.
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Last Modified: Feb 7 14:43:58 CST 1999