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