def transform_com(com, ptcl):
t = Transform()
if len(com) == 3:
t.set_rotation({'psi': meta.psi, 'phi': meta.phi, 'theta': meta.theta, 'type': 'spider'})
else:
t.set_rotation({'psi': meta.psi})
shift = t.transform(com)
# The change in the origin is the projection of the transformed difference vector on the new xy plane.
return shift[0], shift[1]
def subtract(particle,
dens,
sub_dens,
recenter=None,
no_frc=False,
low_cutoff=0.0,
high_cutoff=0.7071):
"""
Perform projection subtraction on one particle image.
:param particle: Tuple holding original (particle EMData, particle MetaData)
:param dens: Whole density map
:param sub_dens: Subtraction density map
:param recenter: Vector between CoM before and after subtraction, or None to skip recenter operation (default None)
:param no_frc: Skip FRC normalization (default False)
:param low_cutoff: Low cutoff frequency in FRC normalization (default 0.0)
:param high_cutoff: High cutoff frequency in FRC normalization (default 0.7071)
:return: Result object
"""
ptcl, meta = particle[0], particle[1]
ctfproj = make_proj(dens, meta)
ctfproj_sub = make_proj(sub_dens, meta)
if no_frc: # Direct subtraction only.
ptcl_sub = ptcl - ctfproj_sub
else: # Per-particle FRC normalization.
ptcl_sub = ptcl.process(
"math.sub.optimal", {
"ref": ctfproj,
"actual": ctfproj_sub,
"low_cutoff_frequency": low_cutoff,
"high_cutoff_frequency": high_cutoff
})
ptcl_norm_sub = ptcl_sub.process("normalize")
if recenter is not None:
# Rotate the coordinate frame of the CoM difference vector by the Euler angles.
t = Transform()
t.set_rotation({
'psi': meta.psi,
'phi': meta.phi,
'theta': meta.theta,
'type': 'spider'
})
shift = t.transform(recenter)
# The change in the origin is the projection of the transformed difference vector on the new xy plane.
meta.x_origin += shift[0]
meta.y_origin += shift[1]
return Result(ptcl, meta, ctfproj, ctfproj_sub, ptcl_sub, ptcl_norm_sub)
