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AS DC - Average images - find & save variance, from doc. file

(8/22/96)

PURPOSE

Adds 2 or more (up to 20000) images together, computing several measures of variance (per point, total, etc.). The sum and the variance images are stored in separate output files.

SEE ALSO

AS [Average images - find & save variance]
AS AD [Average images - add to the existing average - find variance.]
AS F [Average images - find statistics & Q factor map]
AS R [Average images - find & save variance, better]

USAGE

.OPERATION: AS DC

.INPUT: PIC001
[Enter pattern of image name to be added.]

.DOCUMENT WITH FILE NUMBERS: FILES001
[Enter document file name with first column containing numbers of images to be added.]

.ALL, ODD-EVEN (A/O): O
['A' - all images will be added into one output file, 'O' - two subaverages will be calculated: one for odd-numbered images and one for even-numbered images. The next two questions will appear twice for the 'O' option.]

.AVERAGE FILE: AVG001
[Enter name of output file receiving average.]

.VARIANCE FILE: VAR001
[Enter name of output file receiving variance map.]

[Questions for average and variance files are repeated if option 'O' was chosen.]

The following values are then printed out:

 
           Number of images 
           Number of elements 
           Total variance              Total std. deviation 
           Variance. per point         Std. deviation per point 
           Average offset = 0.0 
           Variance of average image 

NOTES

  1. This version of 'AS' does not subtract the average from each images during the calculation of global average and variance. Thus, the statistics calculated are 'Real' and the average offset is always zero. Command 'AS' results in the variance estimator which is usually far 'too optimistic' - the variance obtained is too small and cannot be used for statistical tests.

SUBROUTINES

ADDS

CALLER

UTIL2

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