Basic Information on imgen

Task: imgen
Purpose: All-purpose image manipulator/creator
Categories: utility, map manipulation

        IMGEN is a MIRIAD task that modifies an image, or creates a new
        image.  See also maths to create images based on expressions
        involving X, Y and Z.

Key: in
        The input image, which is to be modified. The default is a map
        with one plane which consists entirely of zeros.

Key: out
        The name of the output image.  The output image has the same
        characteristics as the input image, if present.  If no input
        image is given, the `imsize', `cell' and `radec' keywords give
        the characteristics of the output.  No default.

Key: factor
        Factor to multiply the input image by. This is meaningless if no
        input image is given.  The default is 1.

Key: object
        This determines the type of objects added to the input image.
        Several objects can be given (of the same type or different).
        Minimum match is supported.  Possible objects are:
 
           level      An offset (DC) level.
           noise      Noise (gaussian distribution).
           point      A point source.
           gaussian   An elliptical or circular gaussian.
           gauss3     3D elliptical or circular gaussian (for cubes).
           disk       An elliptical or circular disk.
           j1x        J1(x)/x function
           jet        Jet model with power law brightness.
           shell      2D projection of an optically-thin spherical shell
           comet      2D projection of a parent molecule in comet.
           cluster    standard isothermal 2D projection for cluster gas.

Key: spar
        Parameters which give the characteristics of the object. The
        parameters are given as a sequence of values, with one to six
        values needed per object (depending on the object type). When
        there are multiple objects, the parameter value for the second
        object follow those for the first object, etc. The values are
        as follows:
          Object Type           SPAR values
          -----------           -----------
           level                  offset
           noise                  rms
           point                  amp,x,y
           gaussian               amp,x,y,bmaj,bmin,pa
           gauss3                 amp,x,y,z,bmaj,bmin,pa,bz
           disk                   amp,x,y,bmaj,bmin,pa
           j1x                    amp,x,y,bmaj,bmin,pa
           jet                    amp,x,y,bmaj,bmin,pa
           shell                  amp,x,y,bmaj
           comet                  amp,x,y,scalelength
           cluster                amp,x,y,core radius
 
        Here offset is the offset level, "rms" is the rms value of the
        noise, "amp" is the normally peak value of the object (but see
        options=totflux below), "x" and "y" are the offset positions (in
        arcsec) of the object relative to the reference pixel, "z" is
        the absolute pixel position on the third axis, "bmaj" and "bmin"
        are the major and minor axes FWHM (in arcsec), "pa" is the
        position angle of the major axis (in deg), and "bz" is the FWHM
        (in pixels) in the 3rd dimension.  The position angle is
        measured from north towards east.
 
        Comet scalelength, and cluster core radius are in arcsec units.
        Jet model has brightness with power law index bmaj and bmin
        along major and minor axes.
 
        The default is an object of unit amplitude, at the reference
        pixel, with a FWHM of 5 arcsec in x and y and 5 pixels in z.

Key: imsize
        If not input image is given, then this determines the size, in
        pixels, of the output image. Either one or two numbers can be
        given.  If only one number is given, then the output is square.
        For testing purposes a third number can be given to create a
        cube, no good coordinate headers however are written for such
        cubes.  Default is 256 pixels square.

Key: cell
        The increment between pixels, in arcsec.  Only used if there is
        no input map.  Default is 1 arcsec.

Key: radec
        If no input image is given, this gives the RA and DEC of the
        image, in hours and degrees, respectively.  They can be given in
        hh:mm:ss,dd:mm:ss, or as decimal hours and degrees. The default
        is RA=0, DEC=30.

Key: options
        Extra processing options. Several can be given, separated by
        commas. Minimum match is used. Possible values are:
          totflux  Interpret the "amp" values in the spar keyword as
                   total integrated flux densities (Normally the "amp"
                   parameters are interpretted as peak values).

Key: seed
        Integer used to initialise the random number generator.  The
        same value of SEED produces the same noise, different values
        produce different noise.
 
Revision: 1.6, 2011/10/24 06:35:38 UTC