~F8DATA STRUCTURE: IMAGE ARRAYS.

	There are five arrays in CRE:  TVBUF, Television Buffer; PAC,
Picture  Accumulator;  VSEG,   vertical segments;  HSEG,   horizontal
segments; and SKY, background sky blue array. The dimensions are:

	FIVE ARRAYS.
		1. TVBUF - 216 rows, 288 columns of  6 bit bytes.
		2. PAC   - 216 rows, 288 columns of  1 bit bytes.
		3. VSEG  - 216 rows, 289 columns of  1 bit bytes.
		4. HSEG  - 217 rows, 288 columns of  1 bit bytes.
		5. SKY   - 216 rows, 289 columns of 18 bit bytes.

	Inside CRE,  the video image  size was fixed  at 216  rows of
288  columns of 6 bits  per pixel.   My original idea was  to write a
vision operator that would be applied on a small fixed  sized window;
so I have  had windows 2 by 2;  2 by 3; 4  by 9; 32 by 36;  72 by 96;
and  216  by 288.    That is  216=2*2*2*3*3*3  and 288=2*2*2*2*2*3*3.
Having a fixed  window size avoids a  morass of word packing,   array
allocation  and window splicing.   Having  a window  size constructed
out of powers  of 2 and  3 simplifies what  word packing is  required
and allows me to do area and space computations in my head.

	The image arrays  of CRE are  of course two  dimensional with
the coordinates  in row and columns. Row  number increases going down
image, in the  negative Y axis  direction, which  is also called  the
direction south.   Column numbers increase going right  on the image,
in the  positive X axis direction, which is also called the direction
east.   Video  picture  elements,   or  "pixels"  are thought  of  as
expressing  the intensity of  a square  cell; the cells  are numbered
from 0 to 215 rows,   0 to 287 columns; the  number of a cell is  the
grid locus of its upper left (northwest)  corner; the center locus of
a  cell is at (row+1/5,col+1/2).  A pixel cell is  surrounded by four
segments; the horizontal segments  are numbered 0  to 216 rows, 0  to
287 columns;  the number  of an HSEG  is the grid  locus of  its left
(west)  end point. The vertical segments are  numbered 0 to 215 rows,
0 to  288 columns; the  number of  a VSEG  is the grid  locus of  its
upper  (north) end  point.  These conventions  are  suggested in  the
diagram at the bottom of page 19. ~I1973,800;F8- 20 -