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Ignore:
Timestamp:
Jun 8, 2008, 2:39:37 PM (18 years ago)
Author:
eugene
Message:

cleanup of comments, added "valid" field to pmShutterCorrectin

File:
1 edited

Legend:

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  • trunk/psModules/src/detrend/pmShutterCorrection.h

    r17228 r17994  
    55 * @author Paul Price, IfA
    66 *
    7  * @version $Revision: 1.15 $ $Name: not supported by cvs2svn $
    8  * @date $Date: 2008-03-29 03:10:17 $
     7 * @version $Revision: 1.16 $ $Name: not supported by cvs2svn $
     8 * @date $Date: 2008-06-09 00:39:37 $
    99 * Copyright 2006 Institute for Astronomy, University of Hawaii
    1010 */
     
    1616/// @{
    1717
    18 /*  A mechanical shutter may not yield uniform exposure times as a function of
    19  *  position on the detector.  The typical error consists of a constant
    20  *  exposure-time offset relative to the requested value, ie exposure time is
    21  *  T_o + dT(x,y).  The exposure error, dT, may be measured with the following
    22  *  scheme.  Obtain a set of exposures with different exposures times taken of
    23  *  the same flat-field source; the source must be spatially stable between the
    24  *  exposures, but need not have a stable amplitude.  For an illuminating flux
    25  *  of intensity F(x,y) = F_o f(x,y), the signal recorded by any pixel in the
    26  *  detector is given by: S(t,x,y) = F_o(t) f(x,y) (T_o + dT(x,y)) where F_o is
    27  *  the F_o(t) is the (variable) overall intensity of the illuminating source
    28  *  and f(x,y) is the spatial illumination patter times the flat-field response.
    29  *  Choose a reference location in the image (eg, the detector center) and
    30  *  divide by the value of that region (ie, mean or median):
     18/*  A mechanical shutter may not yield uniform exposure times as a function of position on the
     19 *  detector.  The typical error consists of a constant exposure-time offset relative to the
     20 *  requested value, ie exposure time is T_o + dT(x,y).  The exposure error, dT, may be
     21 *  measured with the following scheme.  Obtain a set of exposures with different exposures
     22 *  times taken of the same flat-field source; the source must be spatially stable between the
     23 *  exposures, but need not have a stable amplitude.  For an illuminating flux of intensity
     24 *  F(x,y) = F_o f(x,y), the signal recorded by any pixel in the detector is given by: S(t,x,y)
     25 *  = F_o(t) f(x,y) (T_o + dT(x,y)) where F_o(t) is the (variable) overall intensity of the
     26 *  illuminating source and f(x,y) is the spatial illumination pattern times the flat-field
     27 *  response.  Choose a reference location in the image (eg, the detector center) and divide by
     28 *  the value of that region (ie, mean or median):
    3129 *
    3230 *  s(t,x,y) = S(t,x,y) / S(t,0,0)
     
    3432 *  s(t,x,y) = f(x,y) (T_o + dT(x,y)) / f(0,0) (T_o + dT(0,0))
    3533 *
    36  *  we can absorb the term f(0,0) into f(x,y) as we have no motivation for the
    37  *  scale of f(x,y).  For any single pixel, over the set of exposures, we thus
    38  *  need to solve for dT(x,y), dT(0,0), and f'(x,y) in the equation:
    39  *  s(t,x,y) = f'(x,y) (T_o + dT(x,y)) / (T_o + dT(0,0))
     34 *  we can absorb the term f(0,0) into f(x,y) as we have no motivation for the scale of f(x,y)
     35 *  -- a normalization for the flat-field is not specified here.  For any single pixel, over
     36 *  the set of exposures, we thus need to solve for dT(x,y), dT(0,0), and f'(x,y) in the
     37 *  equation: s(t,x,y) = f'(x,y) (T_o + dT(x,y)) / (T_o + dT(0,0))
    4038 *
    4139 *  we avoid directly fitting these values as the process would be a non-linear
     
    6260/// Shutter correction parameters, applicable for a single pixel
    6361typedef struct {
    64     double scale;                       ///< The normalisation for an exposure, A(k)
     62    double scale;                       ///< The normalisation for an exposure, A(k) or f'(x,y)
    6563    double offset;                      ///< The time offset, dTk
    6664    double offref;                      ///< The reference time offset, dTo
    6765    int num;                            ///< Number of points used
    6866    float stdev;                        ///< Standard deviation
     67    bool valid;                         // is the fitted shutter correction valid (produce a significant improvement?)
    6968} pmShutterCorrection;
    7069
     
    173172/// Calculate the reference shutter time from the correction data
    174173float pmShutterCorrectionReference(
    175     const pmShutterCorrectionData *data ///< Correction data
     174    pmShutterCorrectionData *data ///< Correction data
    176175    );
    177176
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