Help for STRETCH2B

 PURPOSE:
Procedure STRETCH2B (STRetch TO BYTE) is a VICAR procedure that converts an
image (either single or multichannel) to byte, by means of an automatic
contrast stretch, based upon the input mean and standard deviation. The input
may be of any format excluding COMPLEX (but including BYTE itself), and 
contain any number of channels.  For multichannel inputs, the user may list
the desired band(s) to process, or request that all bands be processed,
without enumeration.
 EXECUTION:
     STRETCH2B uses the VICAR programs COPY, HIST, and C to extract the
requested band and subarea, compute the input mean and standard deviation,
the rescale to byte by forcing the input mean to map to the value or the
MEAN parameter (default = 127.5), and forcing the range of SIGMA (default = 2.5)
standard deviations to map to the 255 DN range about the MEAN.
     If the input is multichannel, each requested channel is processed
one at a time, and each channel is output to a different file.
 EXAMPLES:
     STRETCH2B yuma.half yuma.byte

         In this example, if the input contains one band, that band is
         stretched, using the defaults, then output to yuma.byte.  If the
         input is multichannel, the first input band is stretched.

     STRETCH2B dv12 (dv12.r,dv12.g,dv12.b) bands=(5,3,1) sigma=5

         In this example, Band 5 is stretched to dv12.r
                          Band 3 is stretched to dv12.g and
                          Band 1 is stretched to dv12.b
         with 0 to 255 spanning 5 standard deviations from the mean.

     STRETCH2B sebass sebass 'all

         In this example, all bands of the input are stretched. The outputs
         will have the names sebass.1, sebass.2, sebass.3, ...
 WRITTEN BY:             Ron Alley                   18 Feb 1998

 COGNIZANT PROGRAMMER:   Ron Alley                   18 Feb 1998

 REVISION:               New                         18 Feb 1988