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The input data set, always a halfword disk data set (never a tape).

The output data set. The stretched version of INP. Can be halfword or 
byte as specified. Default is halfword.

4 INTEGERS - A VICAR size field. (Starting_Line, Starting_sample, 
Number_of_Lines, Number_of_samples) Default = it will be read from
the image label.

INTEGER - Starting Line of input image.

INTEGER - Starting Sample of input image.

INTEGER - Number of lines in the input image.

INTEGER - Number of Samples in input image.

This keyword has two valid valuse: BYTE and HALF.
BYTE specifies that the output data set is to be in byte format, with 
DN values from 0 to 255. 
 
HALF specifies that the output is a halfword data set with DN values 
ranging from LVALUE to HVALUE.

SPEED is an integer specifying a line increment.  When computing 
the halfword histogram, only every SPEEDth line will be read. 
Default is SPEED = 1.

PERCENT is a real number specifying the percent of the histogram 
to be saturated (half of PERCENT at each end). 
Default is PERCENT = 0.0.

LPERCENT is a real number specifying the percentage of the lower 
end of the histogram to be saturated. 
Default is LPERCENT = 0.0.

HPERCENT is a real number specifying the percentage of the high
end of the histogram to be saturated. 
Default is HPERCENT = 0.0.

HVALUE is an integer specifying the output DN value to which that 
input DN corresponding to the upper saturation point on the  
histogram is to be mapped.
Default is 511, unless BYTE has been specified in which case the 
default value is 255.

LVALUE is an integer specifying the output DN value to which that
input DN corresponding to the lower saturation point on the histogram
is to be mapped. 
Default is LVALUE = 0.

AREA is composed of four integers which correspond to a size field within 
which the histogram is to be computed.  AREA refers to pixels and is 
relative to line = 1, sample = 1, not to the origin of the size field 
(the default being the entire picture).

EXCLUDE is composed of pairs of integers specifying the exclusion of the 
DN range between them from auto_stretch computation.  EXCLUDE may have up
to 100 pairs of values, to specify multiple DN ranges.

The default is to exclude only 0 DN.

INCLUDE specifies 0 DN is to be included in the auto-stretch computation.
The default is to exclude 0 DN.

Note that if the user specifies a range using EXCLUDE that includes 0, 
then specifying INCLUDE does not work;  all this parameter does is to
suppress addition of 0 DN to whatever range(s) was (were) specified
using EXCLUDE.

PHIST is a keyword specifying the histogram of the input image is to be 
printed.
Default is no histogram will be printed.

EHIST is a keyword specifying the excluded histogram is to be printed out.

SPIKE is an integer specifying the number of spikes in the histogram. 
This parameter is used to control the scale of the frequency axis of the
printed histogram mby setting the SPIKE + 1st highest frequency to the 
maximum value (100), and normalizing all other frequencies to this scale.
Default is SPIKE = 1.

NLIN is an integer specifying the number of grey levels to display in the
printed histogram.  This controls the number of lines printed per histogram.
Default NLIN = 256.

HINC is an integer specifying the grey level increment factor for the 
printed histogram.  This parameter overrides the NLIN parameter. The 
default is to have the program automatically compute the histogram
increment based upon the value of NLIN.

SB is the starting band which is to be output.  The default is 1.

NB is the number of bands which is to be output.  The default is the number
of bands in the input image.

BRANGE is composed of two integers which correspond to the starting band and
number of bands of the input from which the histogram is to be computed.
The default for BRANGE is the values of SB and NB.