Help for MOMGEN

PURPOSE:
 
MOMGEN is the second of a sequence of VICAR applications programs which
measure the radiometric properties of a camera system.  The programs
are designed to support radiometric calibration of flight camera systems.
 
MOMGEN extracts statistical information from specified areas in the
input image(s) and stores the data in a record in the Light Transfer
File (LTF) corresponding to the specified exposure.
 
EXECUTION:
                MOMGEN INP=(E1,E2,E3,...EN) OUT=LTF PARMS
                or
                MOMGEN LIST=file OUT=LTF PARMS
 
OPERATION:
 
Input data to MOMGEN consists of one or more flat field frames taken
at the same exposure from a light transfer or reciprocity sequence.
These images may be input using either the INP or LIST parameters.
 
MOMGEN extracts statistical information from specified areas in the
input image(s) and stores the data in a record in the Light Transfer
File (LTF) corresponding to the specified exposure.  The LTF must have
been previously initialized by LTGEN, the first program in the sequence.
 
Multiple executions of MOMGEN are performed to extract and store data
from each exposure level into the LTF.  Note that if one of these
MOMGEN executions fails due to a tape read error or a bad frame, that
execution may be rerun without having to repeat all other executions.
Each exposure record in the LTF will contain data from the last MOMGEN
execution at that exposure.

After all exposure records in the LTF have been completed by MOMGEN,
data analysis routines may be executed to access the LTF and determine
camera properties such as:
 
        1) System gain constant and read noise floor (see CCDNOISE).
        2) Light transfer curve slope and offset (see CCDSLOPE).
        3) Shutter offset and camera sensitivity (see CCDRECIP).
 
LIGHT TRANSFER FILE FORMAT:
 
The Light Transfer File (LTF) is in VICAR format, and consists of VICAR
labels containing num_areas, num_expos and an array of the exposures,
followed by one record for each exposure level of the light transfer or
reciprocity sequence.

The label array areas contains the size fields for each area
specified (see LTGEN):

        where   AREA(1,K)=starting line for area K
                AREA(2,K)=starting sample
                AREA(3,K)=number of lines
                AREA(4,K)=number of samples
 
The exposure time (msec)is in the label of the LTF file.
Each exposure record contains the number of input frames at that
exposure (NI), and the moments for each area specified:

      NI,OUT(3*NI*NAREA)

where the array OUT consists of moment information in the following order:
 
         SUM(1),SUM(2),...,SUM(NI)          sum of DNs for area 1
         SUM(1),SUM(2),...,SUM(NI)          sum of DNs for area 2
            .    .          .
            .    .          .
         SUM2(1),SUM2(2),...,SUM2(NI)       sum of squares for area 1
         SUM2(1),SUM2(2),...,SUM2(NI)       sum of squares for area 2
            .    .          .
            .    .          .
         SUMXY(1),SUMXY(2),...,SUMXY(NI)    sum of cross terms for area 1
         SUMXY(1),SUMXY(2),...,SUMXY(NI)    sum of cross terms for area 2
            .    .          .
            .    .          .
The exposure records are arranged in order of increasing exposure.
 
Galileo specific:
If an extended exposure dark current record is present, it occurs
first in the LTF (with EXPO=-1.0), followed by the normal DC frame
(EXPO=0.0), followed by the lowest to highest exposure levels.
 
ORIGINAL PROGRAMMER: Gary Yagi, circa 1983
COGNIZANT PROGRAMMER: Gary Yagi
REVISION HISTORY:

   19 MAR 97....T.Huang........Ported from VAX to UNIX to support
                               both Cassini and Galileo.
   23 NOV 93....C.C.Avis.......Added LIST and label search for EXPO
                               Added error checking, max inputs to 50,
                               max size 1024.
   26 APR 88....G.M.Yagi.......Added more documentation: FR 35678.
    4 JUL 86....G.M.Yagi.......Code and documentation clean-up
   19 FEB 85....M.E.MORRILL....INCLUDED EXTENDED EXPOSURE
                                 MODE DEFINITION
   14 JAN 85....M.E.MORRILL....EXPANDED TO 400 AREAS
    1 OCT 84....M.E.MORRILL....VAX-VICAR*2 Conversion
          82....G.M.YAGI.......INITIAL RELEASE
 

PARAMETERS: