Help for CONCAT

PURPOSE:
To easily concatenate images into a regular mosaic grid.

EXECUTION:
gen out=a1.img nl=50 ns=100 ival=0
gen out=a2.img nl=50 ns=100 ival=50
gen out=a3.img nl=50 ns=100 ival=100
gen out=a4.img nl=50 ns=100 ival=150
concat inp=(a1.img,a2.img,a3.img,a4.img) out=a.img ns=200

where (in this example):
a.img looks like:

   a1.img   a2.img

   a3.img   a4.img

The inputs can be of any format type.
The output is byte.
The default is to stretch each input image so that it appears from 0 to 
255 dn in the output.

METHOD:
Concat assumes the input images are the same size.
It stretches all inputs from 0 to 255.
It then orders the inputs into rows on the output beginning from left to 
right starting at the top row and working down. When one row is filled it
begins on the next row. The NS keyword determins the number of pixels per
output row and thus the number of images per row.
Empty mosaic grids are filled with zero's.

HISTORY:
10-1-97  J Lorre. 
COGNIZANT PROGRAMMER:  Jean Lorre