Stochastic screening

Stochastic screening uses mathematical algorithms to randomly space pixels within an established framework. In other words, it is not completely random, but to the human eye does not have a discernible order. The result is variable spacing of dots, which differs from a conventional tint or halftone. Variable dot spacing is also referred to as frequency modulated, or FM, screening.

The examples below show the differences between stochastic and conventional rendering techniques.

- A flat tint uses fixed size dots with fixed spacing between the dots.

- A conventional halftone, by far the most widely used rendering technique in commercial printing, also has fixed spacing between dots, but varies the size of the halftone dots to produce halftone gray scale.

- 1st order stochastic varies spacing between dots, but keeps dot size fixed.

- 2nd order stochastic varies both dot spacing and size

EcoPRO supports first order stochastic screening in the raster mode of the windows 95 / 98 / NT 4.0 driver. However, stochastic screening is a promising but unproved rendering method for screen printing. Most screen printers have achieved better results so far using conventional halftone rendering.