RF - Phase Residual & Fourier ring correlation, 2D ||

(2/21/12)

PURPOSE

Computes phase residual and Fourier ring correlation measures of proximity between two images. Calculates the differential phase residual over a ring with of specified ring width and the Fourier ring correlation between rings of the specified widths and stores the values in a document file. Takes real or Fourier input images.   Example.

SEE ALSO

FRC [Fourier ring correlation and resolution determination ||]
RF 3 [Phase Residual & Fourier shell correlation, 3D ||]
RF SN [Spectral SNR of images, resolution determination & integral SNR ||]
FT [Fourier Transform ||]

USAGE

.OPERATION: RF

.FIRST INPUT IMAGE: FIL001
[Enter the name of the first input file. File can be real or Fourier.]

.SECOND INPUT IMAGE: FIL002
[Enter the name of the second input file. File must be of dimensions as first input file]

.RING WIDTH (RECIPROCAL SPACE SAMPLING UNITS): 1.
[Enter the ring thickness in reciprocal space sampling units.]

.SCALE FACTORS (LOWER, UPPER): 0.8, 1.2
[Give the range of scale factors by which the second Fourier must be multiplied for the comparison. This range is divided into 20 steps for a scale search.]

.OUTPUT DOCUMENT FILE: DOC001
[Enter name of document file in which results are saved.

NOTES

  1. The following measures are reported for each ring:

    a) Normalized Frequency.
     |NORM-FREQ| -- Doc. file register: #1

    b) Phase Residual.
     |DPH| -- Doc. file register: #2

    c) Fourier Ring Correlation, which should be larger than the Critical Fourier Ring Correlation (FRCCRIT) provided for comparison.
     |FRC| -- Doc. file register: #3

    d) Critical Fourier Ring Correlation
     |FRCCRIT| -- Doc. file register: #4

    e) Number of pixels in ring.
     |PIXELS| -- Doc. file register: #5

  2. If you do not want a results file listing use 'MD' operation with option 'VERBOSE OFF'.

  3. Scale search is done separately for each ring in Fourier space. This will NOT lead to sensible results if one of the transforms falls off rapidly in a frequency range where the other transform is strong. The range specified by the user is searched for the lowest value, and the actual scaling factor used is printed.

  4. If the scale range specified contains no maximum, then an error message is printed: "NO MAXIMUM IN CFACT CURVE FOUND FOR RING XX" where XX is the ring number where the error occurred. This is only relevant for phase residual calculation.

SUBROUTINES

RFACTSDO, PR3DB, RFACTSD2, FMRS_2

CALLER

FOUR1

© Copyright Notice /       Enquiries: spider@wadsworth.org