Content-type: text/html Man page of X-GEN


Section: X-GEN Commands (1)
Updated: April 2005
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X-GEN - border  


border [-v] [-ds] [startfm] [endfm] [cutoff]  


"border" computes the active area of the detector face. The active area is determined in the following way:
1. A group of images f=1,...N is read in and the mean intensity at
each pixel <C(X,Y)> is calculated over those images:
<C(X,Y)> = [SUM(f) C(X,Y,f) ] / N
2. The mean of all those values is calculated for all X=1,...W
and Y = 1 ... H:
M = SUM(X,Y) <C(X,Y)> / (W*H)
3. Any pixel for which <C(X,Y)> < Q * M is considered outside the
active area. Any pixel for which <C(X,Y)>= Q*M is considered inside the active area. Q is typically 0.42 but is user-selectable. 4. The outside few pixels are excluded.

The functionality of border (including the run-time options) has now been bound up inside "spots", so there should be no reason to run this program on a stand-alone basis.  


This toggles whether additional diagnostics are written to the XLOG log file during the `border' operation.
This value defines the fraction of the dark-current that
will be subtracted from each detector image in determining the background values used in the border calculation. Default value: 0.
This defines how many pixels "in" from the edge of the
computed active area the defined border will be drawn. Thus if the computed X extremes of the active area at a particular Y value are X = 3 to 502, and the value given in this parameter is 7, then the defined X border at that Y value will be (3+7, 502-7), or (10, 495). Default value: 0.
This specifies the first frame in the range to be
examined in determining which pixels are to be active on the detector face. Default value: first frame enumerated in frame index.
This specifies the last frame in the range to be examined
in determining which pixels are to be active on the detector face. Default value: startfm + delta, where delta is a detector-type- specific value: 20-30 for SDMS, Xentronics, and FAST detectors;; 5-8 for all image plate and CCD detectors. If there are fewer than delta images in the FRAMES file, then endfm will be the last frame enumerated there.
This specifies the fraction of the mean background count
that will be treated as inactive. Thus if the average background count is 200 pixels and the fraction specified here is 0.4, then pixels with counts less than 0.4 * 200 = 80 will be treated as inactive. Default value: detector-type-dependent, ranging between 0.36 and 0.42.


Determine the active area on the default number of images, with the default cutoff for the fraction treated as inactive:
border -q0.41 12 30 Determine the active area over images 12 through 30,
using an inactive-fraction cutoff value of 0.41
To find the active area over images 12 through 30, using a cutoff of 0.41:


Report bugs to Andy Howard at or 312-567-5881.  


Copyright © 2002, Illinois Institute of Technology. See the file 'LICENSE' for information on usage and redistribution of this file, and for a DISCLAIMER OF ALL WARRANTIES




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Time: 02:08:09 GMT, October 03, 2005