Level 2 Help for FIL2

WTMAX

The magnitude of the largest weight to be used in the filtering. Default=32000


PRINT

The OTF as recomputed from the weights is to be printed out. Default is it 
will be printed.


RECT

Use the RECT algorithm to computed the OTF.  Default is the RECT algorithm 
will not be used.


DIVIDE

This is used in the final transformation equation.  Each output point 
is scaled by OUT = A + B*dn / DIVIDE
where A and B are defined by SCALE.  The default is that the sum of the 
weights is used.  If this sum is zero, then 1 is used.


SCALE

This keyword specifies the application of a linear transformation to each
output point .Default is SCALE=(A,B)=(0,1).


NLW

The extent of the weight matrix in lines. Must be odd.  For 1-dim filter,
1 < NLW < 1025. For 2-dim filter, 1 < NLW < 65.  Default is 11.


NSW

The extent of the weight matrix in samples. Must be odd.  For 1-dim filter,
1 < NSW < 1025. For 2-dim filter, 1 < NSW < 65.  Default is 11.


MTF

N pairs of real numbers may be input representing the (amplitude,frequency)
values of the OTF. The last frequency value must be .5. N must be LE 33.
No default.


HIA

N real numbers may be input representing the horizontal amplitude values of
the OTF at the frequencies specified by HIF. 2 < N < 33. No default.


HIF

N real numbers may be input representing the horizontal frequencies cor-
responding to the HIA amplitude values. 2 < N < 33. No default.


VIA

N real numbers may be input representing the vertical amplitude values of
the OTF at the frequencies specified by VIF. 2 < N < 33. No default.


VIF

N real numbers may be input representing the vertical frequencies cor-
responding to the VIA amplitude values. 2 < N < 33. No default.


SN

The signal-to-noise ratio used in the transformation of the OTF into its
Wiener reciprocal.  The reciprocal will correct the image for degradation 
due to the input OTF.  The expression is

 	OTF   =  OTF   / (OTF  **2 + 1/SN**2 )
           out      in      in

SN also serves as the flag to perform the reciprocal.  
Default is no reciprocal.


RANGE

The pair of values (a,b) specifies the range of dn over which the filter
weights are to be applied.


PSF

N real numbers may be input which represent the Point Spread Function or the
right side of the Line Spread Function.  The central weight is first.  The 
OTF will be computed from this.  1 < N < 33.  No default.