TF CTS - Transfer Function - CTF correction with SNR, image/volume

(10/18/15)

PURPOSE

CTF corrects a series of images/volumes by Wiener filtering. Accumulates a CTF corrected sum over all input images/volumes. Similar to 'TF COR' but divides summed input images/volumes by the summed squared CTF images/volumes and adjusts for SNR. Further info on CTF related operations in SPIDER.   Example.

SEE ALSO

TF COR [Transfer Function - CTF correction, image/volume]
TF SNR [Transfer Function - CTF correction, using frequency dependent SNR]
TF C [Transfer Function - Generate a straight, complex, CTF correction image]
TF C3 [Transfer Function - Generate a straight, complex, CTF correction volume]
TF DDF [Transfer Function - Determine Defocus & amplitude contrast]
TF DEV [Transfer Function - Determine Envelope function]

USAGE

.OPERATION: TF CTS

.TEMPLATE FOR IMAGE/VOLUME FILES: img***
[Enter template name of image series to be restored.]

.FILE NUMBERS OR SELECTION DOC. FILE NAME: 1-10
[Enter numbers of files. The file numbers can also be read from a selection document file where file numbers are contained in the first register (not the keys).]

.TEMPLATE FOR IMAGE/VOLUME CTF FILES: ctf***
[Enter template name of file series containing CTF's for respective images. The CTF files have to have the same numbers as corresponding defocus groups (image files).]

.SNR: 100
[Enter Signal-to-Noise Ratio of the images.]

.OUTPUT FILE: mol003
[Enter name for output file.]

NOTES

  1. Input files can be either real or Fourier format. CTF files must be in Fourier format. All files must have the same dimensions. Output file is real.

  2. This operation can also be used for a single image.

  3. Complex CTF files can be generated using 'TF C' or 'TF CT' for 2-D images or by using 'TF C3' or 'TF CT3' for 3-D volumes.

  4. Theory is described in: J. Frank and P. Penczek (1995) On the correction of the contrast transfer function in biological electron microscopy. Optik 98:125-129.

  5. Accumulates a sum over all input images/volumes by multiplying FFT of input image/volume by conjugate of CTF Fourier image. Also computes sum of the squared CTF images/volumes. Divides summed input image/volumes by the summed squared CTF images/volumes adjusted by the SNR. Finally, reverse FFT transforms the output image/volume.

SUBROUTINES

RCTFSS

CALLER

UTIL1

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