MTFCAL (Mar95)                    pipeline                   MTFCAL (Mar95)



NAME
    MTFCAL  --  "calibrate" the measured MTF's as output from HGEOM onto
    a spherical harmonic degree l-scale.
    
    
USAGE
    mtfcal input output
    
    
PARAMETERS
    
    input
        Input MTF file
    
    output
        Output calibrated MTF file.
        
        The  output  file  is  a  2-plane  image  with  time  along  the 
        x-direction  and  degree l along the y-direction.  Image plane 1
        contains the calibrated MTFs and  image  plane  2  contains  the
        estimated errors.
    
    trim_file = "grasplib$plm_200_coarse"
        The  ASCII trimming file used to generate the time series of SHT
        coefficients.  This file provides information on  the  remapping
        type  (latitude  or  sin(latitude))  and  the remap range (i.e.,
        maximum longitude and latitude/sin(latitude)).
    
    data_type = "velocity"
        The type of data being processed.  Choices are:
        
        velocity
            For velocity  (i.e.,  Doppler)  images  (eg.  GONG  velocity
            images).
        
        intensity
            For intensity images (eg. South Pole K-line images.)
            
            NOTE:  how one temporally filters the input images will have
            an affect on how the calibration should  be  performed.   If
            the  temporal filter is applied by ratioing images, the mode
            amplitudes should be approximately constant when going  from
            disk  center  to  the  limb  (since  the  mode  amplitude is
            believed to be a constant fraction of the local  intensity).
            If  the  temporal  filter is applied by differencing images,
            the mode amplitudes will  drop  off  more-or-less  like  the
            limb-darkening  when  going  from  disk  center to the limb.
            The current  version  of  mtfcal  assumes  a  constant  mode
            amplitude  from  disk  center  to  the  limb (i.e., temporal
            filtering by ratioing).
    
    correct_type = "full"
        Defines just what component  of  the  MTF  will  be  calibrated.
        Choices are:
        
        full
            The  full MTF, including contributions from the sky plus the
            optics  plus  the  detector  (i.e.,  integration  over   the 
            detector pixels).
        
        sky_optics
            The  contribution  to  the  full  MTF  coming from the pixel
            integration is removed leaving just  the  contribution  from
            the sky plus the optics.
        
        pixel_only
            Only   the   "blurring"   from   the  pixel  integration  is 
            calibrated.

        mask = yes
            Apply moving mask?
    
        mask_cbr = 0.05
            Moving mask radius for cosine-bell apodization.
    
        mask_EWrad = 0.97
            Maximum mask fractional radius in E-W direction.
    
        mask_NSrad = 0.90
            Maximum mask fractional radius in N-S direction
    

    
    
KEYWORDS
    
    The code reads the following keywords from the input image header:
    
       TS_START     - Starting date/time string (yyyy/mm/dd hh:mm:ss)
       PIXLENX      - Pixel length along the x-direction (in solar images)
       PIXLENY      - Pixel length along the y-direction (in solar images)
       CD1_1        - WCS variable giving the dispersion in x (=time step)
       CD2_2        - WCS variable giving the dispersion in y (=k(r) step)
       RD_SCALE     - Factor by which "radii" were scaled in MTF(k(r)) in
                      order to maintain precision when writing to 16-bit
                      FITS files.
    
    
    
DESCRIPTION
    
    
    
EXAMPLES
    
    
    
TIME REQUIREMENTS
    
    
    
BUGS
    
    Archival data may use  the  date  and  time  keywords  DATE-OBS  and
    STRT_TIM,  respectively.   If  this  occurs,  the  user will have to
    manually add the correct TS_START.
    
    
    
SEE ALSO
    HGEOM, PLM_TRIM