Epson Multi-mode Data Controller MFJ-1278B - Manual (Page 181)

MFJ-1278B MULTI-MODE OPERATIONAL COMMANDS
ASPECT n Mode: FAX Default: 3
Parameter:
n = 2 thru 8
ASPECT is used to establish a reasonable aspect ratio between horizontal and vertical
presentation of 2-Level or 8-Level FAX graphics. The ASPECT command does not apply to
16 Level FAX graphics. It is necessary to have an ASPECT control because the vertical
density a dot matrix printer can represent is much less than the representable horizontal
density.
The ASPECT setting is a ratio of printed: non-printed rows of FAX graphics. The default of
3 means that for every 1 printed FAX row, two rows are discarded. This is the optimum
aspect ratio for HF weather FAX.
If your pictures seem to be elongated horizontally, you should decrease the value of aspect.
The reverse (vertical elongation) is corrected by an increased aspect value.