Stochastic Screens
Stochastic screens are used when printing images on an ink-jet printer. Instead of using an evenly space line screen and varying the value by varying the size of the halftone dots, a stochastic screen uses all the same size dots, but varies the spacing, or frequency of the dots to give the illusion of continuous tone. This is also known as frequency modulation or FM screening. Note that even grayscale images utilize all four (or more) ink colors, CMYK, to produce a neutral tone. Recently, there has been an increased use of stochastic screen printing with printing presses as well.
Halftone vs. Stochastic printing examples. Photo by Carol Garutti
Some ink-jet printers have a difficult time recreating neutral tones because of the need to utilize all colors of ink. This is usually a shortcoming of the printer's standard print driver software. The solution is to use a third party RIP (raster image processor) software package to print . ColorBurst® and Color Byte's ImagePrint are examples of RIP software.
Resolution—DPI, PPI, LPI, SPI, EPI, and EIEIO
There are many terms to describe various resolution attributes when discussing digital imaging. They fall into three main categories: input resolution, file resolution and output device resolution. Keep in mind that most folks use DPI, Dots per Inch to describe most of these attributes. This is fine in most cases, but it helps to understand these different attributes.
On the next page we will look at these different attributes of resolution.
