Xerox DocuPrint Network Printer Series Guide Manual page 56

POSTSCRIPT
2-30
Figure 2-10. Image pixel sequence example
Image:
00000000
00011000
00111100
01111110
00011000
00000000
Sequence A (origin top left, row scan order):
0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 1 1 1 1 0 0 0 1 1 1 1 1
1 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0
Sequence B (origin bottom right, column scan order):
0 0 0 0 0 0 0 0 1 0 0 0 0 0 1 1 0 0 0 1 1 1 1 0 0 1 1 1 1 0
0 0 1 1 0 0 0 0 1 0 0 0 0 0 0 0 0 0
Regardless of which scan order is chosen, the scan proceeds in one
direction (called the fast scan direction) through each parallel slice in
turn, progressing through the slices in a direction called the slow
scan direction.
In sequence A, the fast scan direction is left to right and the slow scan
direction is top to bottom. For sequence B, the fast scan direction is
bottom to top, and the slow scan direction is right to left. The terms
left, right, bottom, and top only have meaning based on the
orientation of the image on the page.
When DocuPrint NPS executes a PostScript program, the principal
product for each page is an image just like the images that can be
incorporated into PostScript programs. The image data is transferred
to the imaging hardware as a sequence of values in laser scan order.
XEROX DOCUPRINT NPS GUIDE TO USING PAGE DESCRIPTION LANGUAGES