Dot patterns
The LQ’s print head is able to print graphics as well as text because graphic images are formed on the LQ about the same way that pictures in newspapers and magazines are printed. If you look closely at a newspaper photograph, you can see that it is made up of many small dots. The LQ also forms its images with patterns of dots, as many as 360 dot positions per inch horizontally and 180 dots vertically. The images printed by the LQ can, therefore, be as finely detailed as the ones at the beginning of this section.
Eight-pin graphicsThe LQ has an 8-pin graphics mode with six densities. Although this mode uses only one third of the LQ’s pins, it produces good quality graphics.
Twenty-four-pin graphicsThe graphics mode that takes full advantage of the LQ’s print head is 24-pin graphics. It has five densities, but for simplicity this explanation will begin with only one of them, triple-density.
Triple-density prints up to 180 dots per inch horizontally. As the print head moves across the paper, every 1/180th of an inch it must receive instructions about which of its 24 pins to fire. At each position it can fire any number of pins from none to 24. This means that the printer must receive 24 bits of information for each column it prints. Since the LQ uses 8-bit bytes of information in its communication with a computer, it needs three bytes of information for each position.