WPDFD Issue #17 - August 01, 1999

DPI

How a laser printer emulates halftone dots using laser dots. With computer printers, dots are also used to build up an image, but in a slightly different way. Laser printers generally try to simulate the effect of a traditional halftone screen with varying sizes of dots. They can usually only produce a single dot size of one color - 300 or 600 DPI are typical. These tiny dots are clustered to produce larger halftone dots in a kind of snail shell pattern.

Sometimes you will hear the phrase 'resolution independent', and as this month's review is about Macromedia Flash 4, I will explain what this means. The first time I encountered this concept was back in the mid '80s when Adobe PostScript was first introduced. Rather than describe an image in terms of absolute pixels, PostScript describes it in terms of vectors. Any rectangle can be drawn by plotting its top left and bottom right co-ordinates.