A standard Vicar input data set
A standard Vicar output file.
FOUR INTEGERS - A standard Vicar size field specifying starting line,
starting sample, number of lines, and number of samples.
INTEGER - Starting line
INTEGER - Starting sample
INTEGER - Number of lines
INTEGER - Number of samples
INTEGER - Specifies the minimum DN value of the input data. The domain of the stretch function is DNMIN to DNMAX.
INTEGER - Specifies the maximum DN value of the input data. The domain of the stretch function is DNMIN to DNMAX.
TWO INTEGERS - LINEAR=(min,max) performs the following transform:
a = (dnmax-dnmin)/(max-min)
DN(out) = a*(DN(in)-min) + dnmin
if DN(out) would be less than DNMIN: DN(out) = DNMIN
if DN(out) would be greater than DNMAX: DN(out) = DNMAX
INTEGER - Input intensities which are a multiple of n are set to the value specified by the DNVALUE parameter.
N INTEGERS - The input DN values specified are set the value
specified by the DNVALUE parameter.
This parameter causes a "gamma" stretch to be performed. The gamma
stretch is defined by the following formula:
/ \
DN = DNRANGE * | (DN -DN ) / DNRANGE | ** (1.0/gamma)
out | in min |
\ /
where the user specifies the parameter, gamma.
In all cases, the output DN is rounded to the nearest integer prior to
output.
N PAIRS REALS - TABLE=(in1,out1,in2,out2,..,inN,outN) will set the
input DN values in1,in2,... to the DN values
out1,out2,... and will linearly interpolate between
these points to compute the intervening DN values.
All DN values outside the range in1 to inN will
remain unchanged unless the parameter BACKGND is
also specified. In that case, all DN values
outside the range in1 to inN will be set to
the BACKGND value. The maximum number of pairs
which may be specified is 100. The values
in1,in2,...,inN must be specified in increasing
order.
N PAIRS INTEGERS - ITABLE=(in1,out1,in2,out2,...,inN,outN) will
set the input DN values in1,in2,... to the DN values
out1,out2,... but will not do any interpolation.
All DN values not explicitly specified, including
those outside the range in1 to inN will remain
unchanged unless the BACKGND parameter is also
specified. In that case, all DN values not
explicitly specified, including those outside the
range in1 to inN, will be set to the BACKGND value.
The maximum number of pairs which may be specified
is 100.
STRING - Allows the user to explicitly specify the transfer
function as a FORTRAN type expression with the
keyword DN as the independent variable. This
is similar to the VICAR program F2. For example,
FUNCTION="2*DN+3" will multiply each input DN
value by 2 and add 3. This will then be the output
DN value, provided it is in the range DNMIN to DNMAX.
If it is less than DNMIN it is set to DNMIN or if it
is greater than DNMAX it is set to DNMAX.
KEYWORD There are two stretch options that are specified by a keyword.
These two (COMP and PSTRETCH) options are lumped together here.
COMP - Causes intensity levels to be complemented. The actual transform
is: DN(out) = DNMAX+DNMIN-DN(in)
PSTRETCH - Specifies that a periodic stretch is to be performed.
The transfer function is:
DN(out)=AMPL/2*SIN[2*PI*FREQ*DN(in)/(DNMAX-DNMIN)+PHI]+DC
where PI = 3.14159
and AMPL,FREQ,PHI,DC are parameters which may be specified
seperately by the user and which have the following defaults:
AMPL= DNMAX-DNMIN
FREQ= 1.0
PHI = 0.0
DC = (DNMAX-DNMIN)/2
TWO INTEGERS - Specifies that a linear post stretch will be performed
following the initial stretch. The initial stretch
will performed over the range DNMIN to DNMAX.
Specifying a post stretch of POST=(LVAL,HVAL) will
then take DN value DNMIN to LVAL and DN value DNMAX
to HVAL. Actually only one stretch is performed;
the composite of the initial and post stretches.
(Default is that no post-stretch is performed.)
INTEGER - Specifies the DN value to use for the CONTOUR and ALARM stretches. The appropriate DN's will be set to this DN value. (Default is DNVALUE=DNMAX)
INTEGER - Specifies a DN value to use as background for the TABLE and ITABLE stretches. All DN values outside the range specified by TABLE, or all those not explicitly specified by ITABLE will be set to this value. (Default is to leave these DN's unchanged.)
REAL - Specifies the frequency to be used in the case of the PSTRETCH (periodic) stretch. (Default is FREQ=1.0)
REAL - Specifies the amplitude to be used in the case of the PSTRETCH (periodic) stretch. (Default is AMPL=DNMAX-DNMIN)
REAL - Specifies the phase to be used in the case of the PSTRETCH (periodic) stretch. (Default is PHI=0)
REAL - Specifies the mean to be used in the case of the PSTRETCH (periodic) stretch. (Default is DC=(DNMAX-DNMIN)/2 )