Dolev 800 - Brisque Application Issues
Class Screening
Worflow for Application
Printing

Conventional
Geometric Dot
HDP
FullTone
Job Type
Explanation of Film Linearization (ExCurve)
Explanation for the need of the Tone Reproduction LUT
Tips for Output Tone Reproduction
Basic Explanation: Dot Gain in Proofing & Printing

Conventional

No Output Tone reproduction is necessary unless you change printing conditions.

The Output Tone Reproduction LUT is built referenced to a linear printed scale. Therefore it is essential that the printer keeps the same printing conditions (paper type, ink density per separation, etc.) when printing the actual job.
If the press conditions are not the same for both Tone Reproduction calibration and actual printing, Dot gain will be different and you will not get the expected results.

Geometric Dot

• When a higher than 250 lpi (70 l/cm) is used it may be necessary to build an Output Tone Reproduction LUT.
• Dot Gain is slightly lower than when using an equivalent conventional Screen Ruling.

HDP

Higher Dot gain must be compensated for by the Output Tone Reproduction LUT.

FullTone

• Higher dot gain has to be compensated for by the Output Tone Reproduction LUT.
• It is less sensitive to ink water balance than conventional screening.
• It is less sensitive to color shifts caused by misregistration.
• It is best to use a densitometer with a narrow band polarizing filter for all dot area measurements.

Job Type

• Newspaper printed on news print stock.
  Flexo - a printing method used mostly for packaging and printing on cardboard, plastic etc.
• Quality Newspaper printed on a higher grade paper than simple newsprint (contains fillers & whiteners).
  Magazine printed on supercalendared, uncoated or lightly coated paper.
• High quality printed on offset enamel stock.
  (Magazine publications, Brochures, etc).
• Top quality printed on highest quality papers with optimum print conditions. Art books, Advertising, trading cards, Annual Reports etc.

Explanation of Film Linearization (ExCurve)

When a file is exposed with no modifications, the result on film is not linear to the file (identical throughout the tone range). Parameters affecting the film linearization are: film type, exposure parameters and processing parameters.

To produce a linear result, that is identical between file and film throughout the tone range, a compensation LUT which takes into account all exposure and processing variables should be built.
In CreoScitex systems, this LUT is called ExCurve .

When a file is sent for exposure, its parameters are modified by the ExCurve.

Explanation for the need of the Tone Reproduction LUT

A certain level of Dot gain is expected during normal printing. Historically, printers have taken into account numerous variables to produce optimum quality while accounting for expected Dot gain. These variables include paper, ink, and numerous press conditions.

For example:
A newspaper is printed at 85 lpi (34 l/cm) w here a midtone Dot gain
of 20-25% is expected.
Another example would be:
Coated paper is printed at 150-175 lpi (60-70 l/cm) where a midtone Dot gain
of 15-18% is expected.

When using very high screen ruling (HDP) and/or FullTone applications, dot gain values are much higher throughout the tone range. Sometimes there is also Dot loss in highlight areas. The file should be modified by an Output Tone Reproduction LUT to compensate for this condition.

The Output Tone Reproduction LUT is used to compensate for both higher dot gain and/or dot loss. This will ensure the expected tone reproduction on press.

Tips for Output Tone Reproduction

A certain level of Dot gain is expected during normal printing. Historically, printers have taken into account numerous variables to produce optimum quality while accounting for expected Dot gain. These variables include paper, ink, and numerous press co nditions.
For example:
A newspaper is printed at 85 lpi (34 l/cm) where a midtone Dot gain
of 20-25% is expect ed.
Another example would be :
Coated paper is printed at 150-175 lpi (60-70 l/cm) where a midtone Dot gain
of 15-18% is expected.

Basic Explanation: Dot Gain in Proofing & Printing

To produce a reliable color proof, one should take into consideration that Dot gain on a printed sheet and Dot gain on a proof may be different.

On the printed sheet Dot gain is caused by optical and physical phenomena:

• Optical Dot gain is caused by light scattering.
• Physical Dot gain is caused by ink spread on the paper surface.
  Some factors are: pressures between cylinders, ink/water balance, substrates, etc.

On the Proof, mostly Optical dot gain is seen.