PROCESS CONFORMANCE TO ISO 12647_2 : A CASE STUDY

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BY:NITA SAMANTARAYROLL NO-130935003PRINTING AND MEDIA TECHNOLOGY

CONTENTS:

1.INTRODUCTION2.METHODOLOGY 2.1.TEST FORM PREPARATION 2.2.INK AND PAPER QUALIFICATION 2.3.PRINTING WITH LINEAR PLATES 2.4.CURVE GENERATION 2.5.PRINTING WITH CURVED PLATES3.RESULTS AND ANALYSIS 3.1.CRF OF IT8.7/4 COLOR CONFORMANCE 3.2.SOLID AND OVERPRINT CONFORMANCE 3.3.TVI CONFORMANCE 3.4.GRAY BALANCE CONFORMANCE 3.5.GAMUT COMPARISON4.CONCLUSIONS5.REFERENCE

1.INTRODUCTION:

ISO 12647_2 is used for offset lithographic process.

METHODS ARE: 1)Matching of tone value curves; 2)Use of near neutral scales; 3)Use of CMYK –CMYK multi

dimensional transforms.

2.METHODOLOGY:

The following Materials And Equipments are to be used:

1) Heidelberg sheet-fed speed master 74

(SM74). 2) X-rite Intellitrax press side color

scanner. 3) Ink with Aqueous coating. 4)paper type-1 should be used.

2.1TEST FORM PREPARATION:

Targets for Analysis: IT8.7/4 basic data set 1)Step wedge target 2)color control stripes 3)gray balance

2.2 INK AND PAPER QUALIFICATION:

Ink should get conform to ISO 2846_1.

-Ink was tested in the RIT Print Applications Laboratory(PAL).

Paper should also get conform to ISO specification.

Cont….

2.3 PRINTING WITH LINEAR PLATES:

LINEAR PLATES( linear run)- Plate dots equals digital dots.

-verified using CC Dot meter. CMYK density and colorimetric measured using X-

Rite Inteli Trex with black backing. Tolerance for solids= 5dEab. If OK , 200 samples printed. 3 sheets taken randomly and average value is

obtained. SID lost: Black-0.06 Cyan and Magenta-0.02 Yellow-0.01

2.4 CURVE GENERATION:

IT8.7/4 chart was measured using X-Rite with white backing.

Solid, overprint and TVI were analyzed using Microsoft excel spreadsheet .

TVI curve is generated using Kodak prinergy RIP.

2 curves obtained: Curve A(CMY) and Curve B(K).

3.RESULTS AND ANALYSIS:

Overall press conformance is determined by the cumulative reflective frequency curve(CRF) between dE and standard data.

3.1 CRF OF IT8.7/4 COLOR CONFORMANCE:

The characterization data set of linear run was compared to the fogra39 characterization data set.

The color difference dE was plotted as the CRF curve.

The color difference for linear plates at 90% is 6.33dE.

For curved plates it is reduced to 3.54dE. The reduction in dE is mainly due to TVI

adjustment.

Cont….

3.2 SOLID AND OVERPRINT CONFORMANCE:

Cont…

The yellow SID is out of tolerance. The reason is black backing and ink dry

back. Yellow SID also affects red and green SID’s

as we can see in the table. The white backing aim points have a higher

c* and l* than black backing. To conform to solid specifications: - the inking is adjusted. - white backing aim points in black backing

measurements.

3.3 TVI CONFORMANCE:

Cont…

The above is the TVI conformance with the linear plates and with the curved plates.

There are 20 nonconforming TVI values in he linear run but none in curved run.

The reason is: - the printing is repeatable between

the two press runs. - the software package used is not

effective in creating the correct transfer curve.

3.4GRAY BALANCE CONFORMANCE:

Cont…

When CMY patches are printed at the ISO 12647_2 conditions , the metric chromaticity (C*) approaches zero.

So improving TVI automatically improving gray balance is needed.

3.5 GAMUT COMPARISON:

The averaged IT8.7/4 measurement of the curved run samples was then used to built the SM74 ICC profile.

By comparing SM74 and ISO coated v2:

-the custom profile is 1/8 smaller than that of the standard offset color gamut in volume.

-the shrinkage is mainly from the white point, and corner points.

Cont…

4.CONCLUSION:

This case study offered us a close-up view of how to implement the TVI method for color conformance according to ISO 12647_2.

Solid and overprint conformance using linear plates and TVI using curved plates.

TVI method helps improve TVI conformance but not gray balance conformance.

REFERENCES:

http://the-print-guide.blogspot.com/2009/06/all-about-dot-gaintvi-tone-value.html

www.fogra.org/index_icc.en.html. ISO Coated v2 (ECI) in ECI Off set

2009. www.eci.org. ISO website: www.iso.org.

http://www.iso.org/

THANK YOU

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