Level 2 Help for SIMPLIFY

The NCLASS value gives an upper limit for DNs for the regions of the input
image.  Only DNs from 1 to NCLASS are considered in finding the most frequent
DN in a window.  The NCLASS value should be set as low as the input image 
allows in order to reduce execution time.  NCLASS must be in the range 1 to
255.  The default value is 255.

The THRESHLD threshold value limits the cases where a DN value will be changed.
Except for the case of unclassified DNs when the REPLACE option is selected,
a DN will not be changed if the most frequent DN does not occur at least the
THRESHLD number of times in the window.  The default THRESHLD value is 4.

The window size gives the linear size in pixels of the moving window used in
testing DNs for changing.  The window size must be an odd integer greater than
or equal to 3.  A size of 3 means a 3x3 window with eight neighbor pixels
surrounding the center pixel.  The default size is 3.

When the REPLACE option is specified, all pixels with a DN of zero will be
replaced with the most frequent DN (in the window) if the window around the 
pixel contains at least one DN in the range 1 to the NCLASS value. 
No replacement is the default.

This optional parameter limits the cases where a DN value will be changed.
If this parameter is entered, only DNs equal to the VALUE parameter can be
changed.  DN values equal to the VALUE parameter are changed or left the
same according to the usual rules based on the THRESHLD and REPLACE
parameters.