C*TTMASK.FOR******************************************************************
C  Program for masking a Fourier transform, with simultaneous correction for *
C     tilted contrast transfer function.                                     *
C                                                                            *
C     Output is written on top of input, so keep a copy if you think it will *
C     need to be done more than once using different parameters.             *
C                                                                            *
C     Input and output masked transform is on stream 1 (INOUT)               *
C                                                                            *
C     Data cards for control data file in free format                        *
C                                                                            *
C  1.   ISIZEX,ISIZEY,DSTEP,XMAG,CS,KVOLT              (*)                   *
C                                                                            *
C  2.   DFMID1,DFMID2,ANGAST,TLTAXIS,TLTANGL   (*)                           *
C                                                                            *
C  3.   ISHAPE=1 Hard edge circular holes      (*)                           *
C          2 Soft edge circular holes (Gaussian weighted to EXP(-2) at edge) *
C                                                                            *
C  4.    RADMIN,RADMAX (ISHAPE = 1 or 2) radius (circular holes)   (*)       *
C         MIN VALUE ON TILT AXIS; MAX VALUE AT 1200 rlu FROM TILT AXIS       *
C         ISHAPE = 1 (Hard edged), = 2 (Gaussian fall off to exp(-2) at edge)*
C                                                                            *
C  5.  AX,AY,BX,BY,IHMIN,IHMAX,IKMIN,IKMAX,RMAX,ITYPE,NUMSPOT  (*)           *
C       AX    etc,lattice parameters from refined NNBOX output in grid units *
C       IHMIN etc, set min/max limits on H,K for lattice generator           *
C       RMAX  Cutoff radius in transform for lattice generator in grid units *
C       ITYPE if = 0, then generate all spots                                *
C             if = 1, then include only spots of given index (see below)     *
C                                                                            *
C  6. Followed by record for each required spot to be allowed through mask   *
C         IH,IK      (*)                                                     *
C                                                                            *
C     ISIZEX,Y    size of image in x and y, checked against file-header.
C     DSTEP       densitometer stepsize in microns.
C     XMAG        magnification of micrograph.
C     CS          spherical aberration coefficient in mm.
C     KVOLT       microscope voltage in KV, used to calculate wavelength. 
C     DFMID1      defocus in one direction (underfocus +ve) 
C     DFMID2      defocus at 90-degs to above
C     ANGAST      direction for DFMID1 in degrees relative to x,y in transform.
C     TLTAXIS     direction of tiltaxis in degrees relative to x,y in transform,
C                   should be between -90 and +90 degrees.
C     TLTANGL     magnitude of tiltangle.
C                       (+ve for less underfocus at start of scan(y=0)).
C                       if tiltaxis is precisely parallel to y, then TLTANGL
C                       should be positive for less underfocus at x=0.
C                                                                            *
C     Derived from MASKTRAN(Version 1.00) and TTBOX      3-JUL-84 (RH)       *
c                                                                            *
C     Version 1.00   3-OCT-85        RH                                      *
C     Version 1.01   5-NOV-85        RH                                      *
C     Version 1.02  29-NOV-85        RH                                      *
C     Version 1.03  17-JAN-86      JMB/RH   Variable hole size               *
C     Version 1.04  17-AUG-87        RH     Bug along y-axis removed         *
C     Version 1.05  18-NOV-87        JMB    Rectangular images               *
C     Version 2.00   3-JAN-92        RH     Converted to UNIX for Alliant    *
C     Version 2.01  16-APR-02        JMS    Bug fix to call IRTORG           *
C                                                                            *
C*****************************************************************************
C