This function is not yet fully documented. This is a transcript of the text-formatted help.

bbphantom  Create a standard phantom (test image)
   IMG=bbphantom(DIM,'type') creates an image of dimension DIM. This is
   primarily intended for use in tomographic problems, but may be useful
   in other fields as well.

   Several test images may also be specified with a parameter, e.g.
   IMG=bbphantom([200,200],'circle',50) creates a 200-by-200 image
   of a circle with a radius of 50 pixels.

   The following phantoms are implemented. If a parameter is followed
   by a value in parenthesis, it will be the default. All lengths are
   specified in pixels.
     'ellip' - solid ellipse
         Par. 1: vector with semiaxes (y-axis, x-axis) or radius.
         Default: dim/2 or min(dim)/2 (ellipse and circle resp.).
         AKA: 'ellipse', 'circle', 'disk'
     'points' - points or circles arranged in a hexagonal grid
         Par. 1: distance between points (min(DIM)/10)
         Par. 2: radius or 0 for points (0)
         AKA: 'hex-balls'
     'boxes' - simple box-phantom with many aligned edges
         Par. 1: boxes per row/column (4)
         Par. 2: intensity-vector, starting with the outer box
     'restest' - resolution-test inspired by the Jaszczak phantom
         Par. 1: number of regions (6)
         Par. 2: radii-vector (starting with outer circle)
         Par. 3: intensity vector (starting with outer circle)
     'head' - Shepp-Logan head-phantom with large uniform areas
         Par. 1: scale-factor, between 0 and 1 (1)
         AKA: 'shepp-logan', 'head1'
     'toft' - As 'head', but with concentrations modified by Peter Toft
         Par. 1: As 'head'.
         AKA: 'modified shepp-logan', 'head2'

   The following options applies to all phantoms.
     'crisp' - Turn off sub-pixel resolution and threshold
     'hard'  - Turn off sub-pixel positioning
     'soft'  - Sub-pixel resolution (default)

   Both 'hard' and 'soft' produce the same average intensity, regardless
   of the image size. 'soft' will further place any image elements at 1/4
   pixel resolution, sometimes producing an undesirable blur.

   'crisp' is useful for investigating how an algorithm responds to hard
   edges and for determing the point spread function, e.g. with the
   'points' phantom.

   Limitation: the 'points' and 'restest' phantoms depends on the image
   size. This will be changed in a future release.

   NOTE: all phantoms are intended to represent linear intensities. To
   view a phantom on a monitor, please use bbimagein to compensate for
   the non-linearity of the display. The 'head'-phantom is the original
   Shepp-Logan phantom; the default for phantom is 'toft'.

     bbimagein(IMG); axis image OFF;

   See also bbimagein,  (image processing toolbox).