This document describes experiments conducted to evaluate color conformance of an offset printing process according to ISO 12647-2. It involves preparing test forms, qualifying inks and paper, and printing using linear and curved plates. Results for color, tone value and gray balance reproduction are analyzed. Conformance is improved when using curved plates which better reproduce tone value curves through adjustments made during printing. The experiments provide insight into implementing tone value control methods to achieve color standards compliance in offset printing.

1. …………………………………………………………………………………………………..
BY:
NITA SAMANTARAY
ROLL NO-130935003
PRINTING AND MEDIA
TECHNOLOGY

2. 1.INTRODUCTION
2.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 PLATES
3.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 COMPARISON
4.CONCLUSIONS
5.REFERENCE

3. 

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.

4. 
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.

5. 
Targets for Analysis:
IT8.7/4 basic data set
1)Step wedge target
2)color control stripes
3)gray balance

7. 

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.

9. 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


10. 




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).

11. 
Overall press conformance is determined by
the cumulative reflective frequency
curve(CRF) between dE and standard data.

12. 




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.

15. 




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.

17. 


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.

19. 

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.

20. 

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.

22. 


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.

23. 
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
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http://the-printguide.blogspot.com/2009/06/all-about-dotgaintvi-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/

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