The task imgen can be used to create an image with a source of some simple model disposition. It can generate noise, point sources, Gaussians, elliptical disks, Bessel functions and DC terms. It can also be used to modify an already existing image by a model. In the following example, we subtract an offset (by -1.5 and 3.5 arcsec in x and y from the reference pixel) circular Gaussian model from an image. The Gaussian parameters are given in the keyword spar (height 0.87 Jy, FWHM of 1.7 arcsec). Note that imgen cannot create elliptical Gaussians unless they align with the x and y axes.
If you wish to create an entirely new image with imgen , you should leave in unset, and specify cell and imsize.