Level 2 Help for MEM

Either two or three input images are required.  The first one is the
degraded image that need restoring (deconvolution).  The second one
is the point spread function (PSF) that the original image was convolved
with.  The third image is the optional default image, which can be
a guess as to what the image should look like.  Most of the time the
default image can be left out.  See the help file for more information
about the degraded image and the PSF image.

The output maximum entropy image.  Has the same format as the input image.

The standard Vicar size field.  Use to select the window out of the degraded
image to restore.  The default is to restore the whole image.

The starting line of the window.

The starting sample of the window.

The number of lines in the window.

The number of samples in the window.

The RMSERROR parameter gives the amount of noise in the data.  This can be 
estimated from the standard deviation of a blank part of the image (use
standard deviation from HIST).  Specifying too large a number will lead to 
an overly smooth image.  Too small a number will prevent convergence.  If 
you don't want to estimate RMSERROR then run MEM with some low value, and
then use the RMS error that is obtained when MEM starts to slow down.

The MAXITER parameter is the maximum number of iterations the program will do.
If the solution is reached sooner MEM will stop before doing that number of
iterations.  Typically 10 to 15 iterations are required.  More difficult 
problems and higher signal-to-noise cases will take more iterations.  There 
little to be gained from doing more than 40 or 50 iterations.

The MAXCRIT parameter specifies the maximum allowed solution criterion.  The
solution criterion is a measure of how close to the maximum entropy solution
the image is for the particular RMS error it is currently at.  Values near
zero indicate that it is at a solution; values near one indicate problems.
The default value for MAXCRIT can nearly always be used.

The MEM program can be restarted using a previous image by specifying the
'RESTART keyword.  The previous (and output) image is specified in the
output image slot.  The parameters and/or images can be changed when restarting
so that adjustments can be made along the way.