RF - R Factor ||

PURPOSE

Computes various measures of proximity between two images: R factor, phase residual, and Fourier ring correlation.

SEE ALSO

RF 3	[Phase Residual & Fourier shell correlation, 3D ||]
RF SN	[Spectral SNR of images ||]
FT	[Fourier Transform ||]

USAGE

.OPERATION: RF

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

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

.RING WIDTH: 1.
[Enter the ring thickness in reciprocal space sampling units.]

.SCALE FACTOR (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.]

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

NOTES

1. 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 along with the RF measures.

2. If the scale range specified contains no minimum, then an error message is printed: "NO MINIMUM IN RFACT CURVE FOUND FOR RING XX" where XX is the ring number where the error occurred.

3. Internally Fourier transforms of input images are calculated. Check manual chapter "FT" for the list of "forbidden" dimensions.

4. The following measures are computed:
   a) R(AKEY et al.) = 2*SUM(ABS(F1-F2))/SUM(ABS(F1)+ABS(F2));
   b) R(McPherson) = 2*SUM(ABS(F1)-ABS(F2))/SUM(ABS(F1)+ABS(F2));
   c) PHASE RESIDUAL = SQRT(SUM[(ABS(F1)+ABS(F2))*DPHI**2]/ SUM(ABS(F1)+ABS(F2)))
   where DPHI = The phase difference between corresponding Fourier coefficients, which should be <45 deg.;
   d) R.M.S ERROR = 2*SQRT(SUM(ABS(F1-F2)**2)/SUM(ABS(F1)**2+ ABS(F2)**2));
   e) FOURIER RING CORRELATION, which should be larger than the Critical Fourier Ring Correlation provided for comparison;
   f) CRITICAL FOURIER RING CORRELATION
   

5. Contents of DOC file and RESULTS file:

    
               COLUMN:       #1          #2      #3        #4          #5                                                   
    
              |NUMBER|   |RING RADIUS   |DPH|   |FRC|   |FRCCRIT|    |PIXELS| 
                         |NORMALIZED|  
   

SUBROUTINES

RFACTSDO, PR3DB, RFACTSD2, FMRS_2

CALLER

FOUR1