TF LM4 - Transfer Function - Estimate image formation parameters

PURPOSE

Apply nonlinear regression to estimate EM image formation parameters. Outputs to operation line registers.

SEE ALSO

TF ED

[Transfer Function - Estimation of CTF parameters]

USAGE

.OPERATION: TF LM4 [b],[c],[b1],[b2]

[On output, [b], [c] are B-factor of envelope function, and CTF related Noise. [b1], [b2] are parameters of base-line noise]

.INPUT FILE: pow001
[Enter name of the 1-D power spectrum file.]

.PIXEL SIZE [A], SPHERICAL ABBERATION CS [MM]: 2.8, 2

.WAVELENGTH LAMBDA [A]: 0.037
[Enter the wavelength of the electrons. The value used in this example corresponds to 100kV. A table of values is listed in the glossary under lambda]

.AMPLITUDE CONTRAST RATIO [0-1]: 0.1

.ESTIMATED DEFOCUS [A]: 27000
[Enter the defocus (Angstroms) of micrograph. The defocus can be pre-estimated using 'TF ED' ]

NOTES

2. The image formation is PW(f)=CTF(f)**2*ENV(f)**2*NOISE1**2+NOISE2**2.

3. CTF parameters are pre-estimated using linear constrained and uncontrained method.

4. ENV(f) = EXP(-.5*(f/B-factor)**2).

5. NOISE1 = Constant.

6. NOISE2 = EXP(Af+B).

7. Implemented by: Zhong Huang

SUBROUTINES

TFLM4

CALLER

UTIL1