Jaws
gDocError-diffusion screening, or EDS, was developed primarily for proofing applications at relatively low resolution. The screen is created programmatically as the page is rendered, the color value at each pixel is examined in turn, and in comparison with those of the surrounding pixels, to decide which screen dots should be turned on or off. The resulting screen can therefore respond to the specifics of the contents of each page.
EDS can produce very good results under the right circumstances, but is too slow for some applications, including digital production presses.
It’s also not generally regarded as suitable for platemaking, as the dot pattern produced is not guaranteed to be printable on press.
EDS can also suffer from quality issues such as tear-away (where visible artifacts appear consistently on one side of a high-profile edge in the rendered graphic).
It can also sometimes leave uneven tints in flat tones including mottle or grain, and ‘rivers’ where long, narrow artifacts appear as unscreened pixels are randomly aligned. The Harlequin EDS screen is Harlequin Error Diffusion Screening, or HEDS.
