% @(#)rebin_rota.hlq	17.1.1.1 (ESO-IPG) 01/25/02 17:43:52 
%++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
%.COPYRIGHT  (c)  1990 European Southern Observatory
%.IDENT      rebin_rota.hlq
%.AUTHOR     KB, IPG/ESO
%.KEYWORDS   MIDAS, help files, REBIN/ROTATE
%.PURPOSE    On-line help file for the command: REBIN/ROTATE
%.VERSION    1.0  03-JUNE-1986 : Creation, KB
%----------------------------------------------------------------
\se
SECTION./ROTA
\es\co
REBIN/ROTATE						04-MAY-1994  KB
\oc\su
REBIN/ROTATE in out [rot_specs] [ref_frame] [ref_flag]
	rotate + rebin an image
\us\pu
Purpose:
           Rotate a 2-dim image by given angle around rotation point and rebin
           with new stepsizes.
\up\sy
Syntax: 
           REBIN/ROTATE in out [rot_specs] [ref_frame] [ref_flag]
\ys\pa
           in = name of input frame
\ap\pa
           out = name of output frame (will be created by this command)
\ap\pa
           rot_specs = angle,rotx,roty,scalx,scaly (a) or KEYWORD (b)
\\
               angle = rotation angle in degrees (positive angle leads to
               counterclockwise rotation);
\\
               rotx,roty = coordinates of point around which the image will be
               rotated, or C for using coordinates of center pixel as "rotation
               point";
\\
               scalx,scaly = scaling factors in x and y, the stepsizes of the 
               output frame will be: stepsize of input frame * scaling factor;
\\
               if no reference frame is given (see following par.), the start
               of the result frame will be set so, that the coordinates of this
               "rotation point" will remain the same in the resulting image;
\\
               if rot-specs = string KEYWORD then the transformation matrix for
               the rotation is taken from the keyword TRANSFRM which should 
               have been filled by the Midas command ALIGN/IMAGE before;
\\
               defaulted to 45.,C,C,1.,1. (i.e. option (a))
\ap\pa
           ref_frame = name of optional 2-dim reference frame;
\\
               if a reference frame is given, the start and stepsize for the
               output frame will be aligned with the reference frame (that 
               means that scalx,scaly of parameter 'rot_specs' will be
               overruled by the stepsize of the reference frame);
\\
               This is also valid, if option (b) is used.
\ap\pa
           ref_flag = YES or NO - if set to YES the output frame will have
               the exact start values, step size and no. of pixels be as in
               the reference frame (only applicable if reference frame given
               and useful for the KEYWORD option (b));
\\
               defaulted to NO
\ap\sa
See also:
           ROTATE/CLOCK, ROTATE/COUNTERCLOCK, ALIGN/IMAGE, REBIN/LINEAR
\as\no
Note: 
           If no reference frame is given, the output frame will be the smallest
           rectangle containing the rotated image, otherwise it has the size of
           the reference frame.
\\
           All pixels in the output frame which are outside the rotated image
           are set to a user defined Nullvalue (2. element of keyword NULL).
\\
           The input image is first rotated and then the pixels of the result
           frame are sampled with the stepsize defined by saclx,scaly
\\
           If ref_flag is not set to YES, the result frame might look as if
           it were not aligned with the reference frame (especially, when there
           was only a very small rotation angle). But if you e.g. divide these
           two frames, you see that the objects you used for the ALIGN/IMAGE
           command are aligned correctly.
\on\exs
Examples:
\ex
           REBIN/ROTA conejo tortuga 23.4,22.,31.
             Rotate image `conejo.bdf' by 23.4 degrees around point with 
             coords.  (22.0,31.0) - this is not necessarily a pixel of the
             image;
\\
             result will be stored in frame `tortuga.bdf'
\xe\ex
           REBIN/ROTA conejo tortuga 23.4,C,31.,1.5,1.5
             Rotate around point with x-coord. = coord. of x-center pixel and 
             y-coord. = 31.0. Rebin output image `tortuga.bdf' with stepsize
             which is 1.5 * stepsize of `conejo.bdf'.
\xe\ex
           REBIN/ROTA conejo tortuga 23.4,C,31.,1.5,1.5 ballena
             As above, but the size of the output frame is determined by the
             size of the reference frame `ballena.bdf' and the scaling values
             are taken as the ratio of the stepsize of `ballena.bdf' and
             `conejo.bdf' (i.e. the scale values 1.5,1.5 are overriden!).
\xe\ex
           REBIN/ROTA conejo tortuga KEYWORD ballena yes
             Rotate image `conejo.bdf' and use keyword TRANSFRM (which was
             setup before via the ALIGN/IMA command) to get rotation angle,
             sample offsets and scaling factors.
\\
             Image `tortuga.bdf' will have the  start coords., step sizes and
             no. of pixels as image `ballena.bdf'.
\xe \sxe