Nailing Spot Color Reproduction

Transcription

1 #COLOR19 Nailing Spot Color Reproduction What you should know about Spot Color Processing

2 Who am I? Thorsten Braun Technical Director of ColorLogic GmbH Former R&D Manager with LOGO GmbH & Co.KG and Gretag-Macbeth AG Inventor of ProfileMaker, ColorAnt, CoPrA, ZePrA In the US since 2012 (CrossXColor, Inc.)

3 Introduction Why is it important? Growing topic Confusing and complex What are main aspects to consider? How can this help you with your print production?

4 From document to production Two Sample Jobs Two Sample Printers

5 Key Questions Which Output Device to use? Gamut Size vs. Production Cost What is required for good enough quality? Tolerances, Gradients, Iteration How should I convert? Color Purity vs. Accuracy

6 Spot Color Prediction (Example) Know before print!

7 Spot Color Prediction (Essence) Job 1 Job 2 ISOcoated_v2_eci.icc ISOcoated_v2_eci.icc 7C Indigo_CorrectedV3_TAC370_Smooth_B21343.icc 7C Indigo_CorrectedV3_TAC370_Smooth_B21343.icc

8 How accurate is the prediction? Profile Precision Profile Integrity Job/Conversion Properties Theory vs. Reality

9 German vs English I Da bist du schwer auf dem Holzweg. You are heavy on the wood-way. You are barking up the wrong tree.

10 Select Output Device

11 Job Properties to handle Full Tones Gradients Overprints between Spot Colors and Process Colors Overprints between Spot Colors Any other color combination

12 Types of Color Libraries Lab Libraries (solids) Spectral Libraries (solids) Better Prediction Viewing Conditions Libraries with Gradients CxF/X-4 Full Testcharts

13 Color Library Standards (Examples) aco, ase, acb, CxF Pantone Live CxF/X-4 CGATS Lab Full Tones X X X X Lab Gradients X X (X) Spectral Data X X X X Advanced Gradients (X) (X) X (X) Overprints (X) (X) (X) (X) Technically possible, but not really standardized

14 CxF/X-4 Spectral only No Lab solids allowed No Lab gradients allowed Spot on Black => Opacity Color Acceptance

15 Alternate Color Spaces Lab vs. DCS Full Tone & Tint Transform Embedded CxF/X-4 (Output Intent) Purpose vs. Accident (Reliability?)

16 German vs English II Da haben wir den Salat. There we have the salad. Now we're in a fine mess.

17 Job 1 Review 100% Spots, only No Overprints Color Library Full tones Lab is sufficient

18 Job 2 Review Gradients Overprints Color Library Define Gradients or Linearity Spectral Data recommended Full Testcharts preferred

19 Conversion Steps Target values Getting vs. Guessing Prediction Models Generating the output values ICC conversion Device Link Technology We have to understand the Process!

20 Spot 1 Spot 3 Job C Printing Color Space Spot 1 Spot 2 B Spot 2 A Spot 3 Color Library Color Generation? Target Values Printing Color Space Color Model

21 German vs English III Ich verstehe nur Bahnhof. I only understand train station. It's Greek to me.

22 Color Model Limitations Print Sequence Document Color Space / Output Intent PDF Ink Sequence Opacity CxF/X-4 provides information Automatic Calculation Color Acceptance Depends on Print Order Not predictable ICC Profiles are not spectral (current standard) No standard, depends on manufacturer

23 Quality to expect (Sample results) Library vs. Job (Avg/Max de00) Full Tones Gradients* 2C-Overprints* nc-overprints* Library vs. Job (Avg/Max de00) Full Tones Gradients* 2C-Overprints* nc-overprints* Lab Full Tones 0.9/3.1** 2.0/6.0** 2.3/10.0** Lab Gradients 1.8/6.0** 2.5/11.2** Spectral Full Tones 0.9/3.1** 1.6/3.9** 1.8/6.0** Spectral Gradients 1.6/3.3** ~3.0/~10.0*** 2.0/7.5** ~4.0/~15.0*** Advanced Gradients 1.6/3.3** 1.8/7.5** Overprints * Linearity must be specified ** Good CMYK Sample data *** 7CLR FOGRA Multicolor Forum 2018

24 German vs English IV Ich glaube mein Schwein pfeift. I believe my pig whistles. Are you kidding me?

25 How to improve? Avoid critical overprints Better Color Models Provide more and better data Iterative approaches Use a reference for more consistency

26 What is the Reference? Overprinting Spot Colors is device dependent! The Output is hardly predictable. Define a Reference system for consistent results! Also Proof quality is limited but you may use it as a reference!

27 Workflow with a Reference system I Job Reference Reference Library Target Printer 1 Printer 2

28 Workflow with a Reference system II Job Reference Printer 1 Library Target Printer 2

29 Iterative Optimization Only for digital printing Easy for Full Tones Possible for Gradients Optimize full libraries or per job For overprints: Complex & Massive number of combinations Number of 2-4 combinations Full Tones only / /70/

30 Iteration Example (Job 1)

31 Initial Output First iteration Second iteration

32 Proof vs. Production Accuracy Channel Properties Tolerances Production Limitations

33 Linearity vs. Gradients SCTV/ISO20654 Defines distances only! How about the color hue? Limitations on extreme cases Gradients may not match the target linearity! Linearity combined with gradients

34 Sample Jobs - reviewed Job 1 Job 2 CMYK sufficient Full Tone Spots Iterate Spot Library Easy Job! 7CLR required Gradients and overprints Advanced Spot Library Reference system recommended Complex Job!

35 Conclusion Select Output System wisely Spot Colors complexity is job dependent Spectral data improves quality Use Spot Colors isolated, if possible Consider a reference for cross media production

36 What did we learn?

37 What did we learn? I believe my pig whistles. I only understand train station. You are heavy on the wood-way. There we have the salad.

38 Interested in more See us at booth in the vendor area us Download products and request demo licenses