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Ink Sequence of EG and its Affect on Color Gamut
• Nina Davis
Project Mission Statement
• Q: Can the model for predicting best sequence be affectively applied using drawdowns before going to press?
• Q: Do consumers notice a difference in color when we change print sequence?
Project Scope
• Project addresses these main points:–Effectiveness of predicting gamut
change with drawdowns–Detection of gamut change by
consumers
Drawdowns - Conditions
• Ink – Mono-pigment UV ink for flexo• Substrate – White PET Label• Hand proofer and aniloxes
Drawdowns
• Conduct drawdowns of the following scenarios:–CMYKOGV primaries–OGV primaries and their CMY pairs (two
ways)–CMYOGV over K for opacity
Drawdowns - Measurements
• Each drawdown was measured for:–Density–L*c*h*–Opacity
• Tools: xRite eXact
Drawdowns - Data
• Using opacity data, best sequence was indicated by putting primaries in order of most to least opaque.
Color V O M Y C G
Opacity 12.8 7.1 5.4 3.9 3.6 3.3
Drawdowns - Data
• Change in overprint C* values were used to evaluate sequence.
• Larger C* values indicated better sequence.
Pair OY/YO YC/CY CG/GC VM/MV VC/CV GY/YG OM/MO CM/MC YM/MY
C* 107.48 64.57 72.77 58.79 74.18 60.52 89.24 51.48 86.01
C* 104.12 63.55 72.42 54.99 75.63 86.76 78.14 49.35 77.43
ΔC* 3.36 1.02 .35 3.80 1.45 26.24 11.1 2.13 8.58
• ΔE of OGV is measured to each primary and the area of the triangle formed between the points is calculated.
• Triangles with larger areas determined to yield the best sequence.
Pair OY/YO YC/CY CG/GC VM/MV VC/CV GY/YG OM/MO CM/MC YM/MY
Area 303.06 2007.7 455.46 435.95 501.07 1741.45 787.41 2347.90 2522.68
Area 258.34 2015.54 408.56 568.16 618.06 1734.37 394.66 2127.35 1927.93
ΔA 44.72 7.84 46.9 132.21 116.99 7.08 392.75 220.55 594.75
Drawdowns - Data
• Simplified calculation of real gamut volume by examining overprint tetrahedron.
• Largest volume indicates best sequence.
Pair OY/YO YC/CY CG/GC VM/MV VC/CV GY/YG OM/MO CM/MC YM/MY
ΔVol 49.9 2328.5 250.8 .8 1615.6 31.5 8182.4 3545.6 13005.3
Drawdowns - Data
Press Conditions
• Sequences:– KVOMYCG – calculated using opacity
– KOYCGVM – change in overprint chroma
– KCGOYMV - area of the chroma/hue triangle– KOGYCVM – tetrahedron volume
Press Conditions – Cont.• Same ink and substrate
• Aniloxes:
– K 800/2.8 - O 900/2.2
– C 1200/1.8 - G 1200/1.8
– M 1200/1.8 - V 800/2.8
– Y 1200/1.8
• .067 digital photopolymer plates
• Composite doctor blades• Medium durometer stickyback
Measurements
Measurements
900000910000920000930000940000950000960000970000980000990000
10000001010000
KCGOYMV KOGYCVM KOYCGVM KVOMYCG
106.1%106.6%101.1%100%
• 75 colors in/out of gamut
• Both gamuts produce 70% of the Pantone Solid Coated library, but with varying ΔE.
• Higher max ΔE with smallest gamut.
Measurements
Consumer Product
Consumer Opinion
• Of those who saw a difference, were equally likely to prefer either sequence.
• 67% preferred the sample produced with the smaller gamut.
• 53% preferred the sample produced with the larger gamut.
ConsumersWhoSeeADifference
Yes
No
Consumer Product
Consumer Opinion
• Again, those who answered were equally like to prefer either sample.
• 28 people preferred either sample.
ConsumersWhoSeeADifference
Yes
No
Conclusions
• Printers may be able to utilize drawdowns before going to press to estimate best gamut.
• Sequence may not have a profound effect on the way a consumer sees a product.
• Other areas for research:– The placement of black within the sequence.
– Additional verifications using drawdowns for prediction.
