(v13) Screening definitions

This page applies to Harlequin v13.1r0 and later; both Harlequin Core and Harlequin MultiRIP

AM: Amplitude modulation. Halftones that vary the size of dots whilst keeping their placement constant are described as amplitude modulated.

Channel: (or color channel). Typically, one of the inks, donors, or other marking agents used by a final output device. In this section, the word “channel” is used when describing rasters, because the RIP always halftones a raster format intended for the final output device, so the various color elements within that raster are inherently device-specific ones. The mapping of device-independent colors to device-specific channels need not be one-to-one, such as when proofing or separating.

Color channel: (or channel) Typically, one of the inks, donors, or other marking agents used by a final output device. In this section, the word “channel” is used when describing rasters, because the RIP always halftones a raster format intended for the final output device, so the various color elements within that raster are inherently device specific ones. The mapping of device-independent colors to device-specific channels need not be one-to-one, such as when proofing or separating.

Display-list: Generally, this is the list of graphic elements making up a page. In the Harlequin RIP, the display-list is fundamental to the architecture and its structure reflects the band divisions within both the page and the rendering process.

EDS: Error diffusion screening. A halftoning method whereby quantization error is distributed over neighboring pixels.

FM: Frequency modulation. Halftones that vary the placement of dots whilst keeping their size constant are described as frequency modulated.

Halftone: The use of dots of varying size, density or placement to give the illusion of continuous tones to the naked eye.

Halftone instance: In this section, a value that differentiates one particular screening or halftoning implementation or method from another. Different color channels may employ different halftone instances, for example, even though the halftones they employ share common characteristics.

HDLT: Harlequin Display List Technology. This enables customization hooks to be called at strategic times, between interpretation and rendering, during the creation of the RIP's display list.

HDS: Harlequin Dispersed Screening. A patented FM halftoning method having some properties similar to traditional AM halftones.

HPS: Harlequin Precision Screening. A feature to achieve more accurate angles in traditional AM halftones, in order to minimize moiré.

Raster: A two-dimensional array of pixels (picture elements).

Screening: Originally, a photographic method of creating halftones. In this section, the process of reproducing a page or parts of a page in the form of a halftone raster.