Epson SQ-2550, User Manual

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Graphics
Using hand-calculated data to print graphics
With what you know now, you can use the simplest application
of graphics - using hand-calculated data to print graphic
images. While this method is the most tedious, it helps you
understand dot graphics. Also, it is useful for small graphic
elements that are used many times.
The illustration below shows how you can use a grid to plan
where you want dots to be printed. This grid is for a single
line of graphics 42 columns long. Since each line of 24-element
graphics is approximately 1/8th of an inch high and since
triple-density graphics prints 180 dots per inch horizontally, a
design planned on this figure will be about 1/8th of an inch
high and less than 1/4th of an inch wide.
The actual pattern that the printer prints on the paper is, of
course, made up of dots that overlap each other both vertically
and horizontally. The reason the planning grid uses an X for
each dot is that using an accurate representation of the dots
makes calculating the data numbers difficult because they cover
each other. Therefore, remember that each X represents the
center of a dot, and the dots actually overlap each other.
4-16 Software and Graphics