Specifications

The Digital Fine Print Course

Printing a Fine Print

RIP Linearization

3. Once the media’s ink limits have been determined the next step is linearization.

Linearization test charts are usually supplied with the RIP software, and should be avail-

able in different formats to suit different spectrophotometers. They usually comprise step

wedges in cyan, magenta, yellow and black, and sometimes also combinations of CMY and

CMYK. At least 21 steps per colour are considered necessary to accurately linearize a RIP,

though some linearization test charts can contain several hundred patches.

Once printed and dried, the linearization test chart is read, either directly into the RIP

software by connecting the Spectrophotometer directly to the RIP's computer, or by read-

ing the linearization test chart with a remote spectrophotometer, and then transferring

those readings (in the appropriate format for the RIP) into the RIP's software for process-

ing. Processing usually only involves selecting the new linearization data/file in the RIP

software as the current linearization for that printer and media 'environment/preset'.

Linearization is a critical step because it puts the printer into a balanced and known con-

dition to which it can be returned through subsequent re linearization.

To maintain its accuracy the printer needs to be re linearized on a regular basis, and the

new linearization data saved into the current 'environment/preset'. The re linearization

frequency is often determined by experience as in "The prints are no longer looking cor-

rect so it must be time to re linearize the printer", or are included in a regular mainte-

nance schedule. Sometimes re linearization needs to be performed several times a day in

the case of a printer whose output shifts or drifts during a normal working day.

Digital photographic printers are usually re linearized at the start of each day or shift or

even each roll of paper, or immediately before printing colour sensitive work, such as BW

images (printed on colour photographic paper).

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