Webinar -- G7 for Grand Format Printers


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Webinar -- G7 for Grand Format Printers

  1. 1. How consistent is your color in printing? G7 for Grand Format Printers X-Rite Color Management for Grand Format Printers
  2. 2. Sponsor • X-Rite is the global leader in color science and technology • Pantone is part of the family • Mature product line for printing and graphic arts markets
  3. 3. Today's Speaker – Dan Reid o Founded in 1998 to help business realize the benefits of color management o Consulting and product sales for some of the largest and smallest print providers o Early adopter of G7 calibration technique for non-litho applications. Certified by IDEAlliance in 2006
  4. 4. First Webinar o PDF Slides – http://slidesha.re/17vHP5W o Recorded Webinar – http://bit.ly/1coYVIi • This is webinar is also being recorded o We will send links to the slides and recording Part 1 — Printer Calibration
  5. 5. • Quick Poll • G7 Myths & Background • Ways to Achieve G7 Compliance • G7 Tools to Achieve Compliance • Tips • QA Agenda
  6. 6. (1st Poll Question) • Have you implemented G7 calibration method at your business?
  7. 7. • If you have not implemented G7, why not? (2nd Poll Question)
  8. 8. • RGB files by their nature are neutral • Files from RGB to CMYK are typically a US Web Coated (SWOP) v2 or GRACoL (2006) separations • Though US Web Coated in not based on G7 using GRACoL as a source ICC profile in your RIP usually works Invariably source files are either RGB or CMYK
  9. 9. Can you see a difference? GRACoL – ICC profile Assigned US Web Coated (SWOP) v2 – Original
  10. 10. GRACoL – ICC profile Assigned US Web Coated (SWOP) v2 – Original Can you see a difference?
  11. 11. • Equal values of RGB = neutrality • Common agreed gray balance triplet for CMYK for mid-tone is 50/40/40/0 o GRACoL 2006 and Web Coated SWOP 2006 are based on G7 calibration process. Neutrals in RGB and CMYK
  12. 12. AFTER G7 Correction Before G7 Correction
  13. 13. • Just getting prints neutral won't alone achieve a visual match • Using a method to consistently achieve a visual contrast relative to the substrate color is missing key So neutrality is well defined, what about visual contrast?
  14. 14. • Formally introduced in 2006 by IDEAlliance • Origins and original calculations were based on lithographic printing • Slowly introduced and tested in other printing processes • Most Grand Format RIPs supports G7 calibration method either directly or indirectly by color reference Brief History of G7 Method
  15. 15. Common Myths about G7 • G7 does not replace color management • If you are using a printing process other than commercial (litho) printing then G7 calibration provides little benefit • Color ICC profiles can achieve the same results
  16. 16. •ICC profiles are not designed to fix or compensate o poor color calibration o poor gray balance o Consistent visual appearance ICC Profiles
  17. 17. • Targeting G7 via color management may not be sufficient meet required tolerance metrics • Output (Printer) ICC profile typically does not have enough samples to be accurate enough • Output (Printer) ICC profile does not have enough resolution for accuracy o Table resolution needs to be higher resulting in larger sized ICC profiles (MB). Not a huge deal, but not all RIP profiling solutions allow adjustable table resolution • May necessitate manual ICC Profile tuning to achieve a match within tolerance • Possible but requires some trial and error • Tedious | time consuming G7 via Color Reference
  18. 18. Of course no one would consider building ICC profiles without first optimizing color balance There could be a color bias the ICC profile will faithfully record ICC profile will not automatically re-distribute color tones to achieve smooth gradients Poor Color Calibration
  19. 19. • If your ICC profiling chart prints with a color cast then the ICC profiling software will record that bias • ICC Profiling Black Generation options define how to black is used to create neutrals (GCR/UCR) o Invariably there are not enough samples available to provide sufficient accuracy on first attempt from the ICC profiling chart o Improvements are possible by iterating correction by re-printing profiling charts with corrections applied, measure, and evaluating if further improvement is needed Poor Gray Balance — Color Cast
  20. 20. How many near neutral and neutral patches do you see?
  21. 21. Black Generation options define how to gray is built but..... o Black Gen setting can minimize color bias but do not address tone response curve o Tone Response curve provides the “look” of output Poor Gray Balance — Color Cast
  22. 22. • Most Grand Format Printing RIPs do not offer iterative color tuning o Too many medias, not enough time o Not practical – there is typically some variance in printing that is higher than color tolerance targeted o Traditional color match using ICC profiles in a RIP may be sufficient to pass within tolerance • No mechanism to compensate other than re-linearization which may not be sufficient since the goal is not meeting a gray balance tolerance • May require more frequent profiling of printing device if re- linearization does bring the printer back in line within tolerance G7 via Color Reference
  23. 23. •Output color gamut is frequently smaller than the source color gamut of SWOP or GRACoL o Using standard ICC profiles sometimes can result in severe compression o Accuracy in color compression is not always sufficient • Directly related to how many samples are taken • Some color / neutrals need additional sampling to improve accuracy Grand Format Printing ain’t GRACoL or SWOP
  24. 24. G7 Grayscale o Basic requirement for G7 Qualification G7 Targeted o Used for printing presses – not Grand Format o Color Gamut similar to ISO 12647-2 / GRACoL / TR- 15 G7 ColorSpace o G7 Grayscale required but many proofing RIPs use color management instead to G7 correction curves achieve G7 compliance o Color Match verified against G7 reference typically GRACoL or SWOP3 G7 Compliance Levels
  25. 25. G7 Extreme o No color management (no reference print conditions) but G7 Grayscale applied o Defines setup where color gamut is larger that source (ie GRACoL) and not compressed to meet a reference like G7 ColorSpace o Usually not “accurate” color but pleasing G7 Compliance Levels
  26. 26. OriginalGRACoLSep GRACoLSepprintedw/oColorManagement File Printed with G7 cal but no Color Management
  27. 27. GRACoLSepprintedw/oColorManagement File Printed with G7 cal but no Color Management AKA, G7 Extreme
  28. 28. Original GRACoL Sep Original GRACoL Sep
  29. 29. • Better and more consistent match across printing technologies • Improved visual color appearance across different substrates • Alignment with source ICC profiles based upon G7 method (GRACoL & SWOP) • Improved recalibration process that aligns with a visual system using only 300 patches o Improves the shelf life of ICC profile if based upon G7 Benefits of G7 for Your Business
  30. 30. • This defines how contrasty a image appears to the eye. o Some materials inherently have a lower visual contrast o Especially problematic in non-litho applications o Media and printing technology have direct impact on how an image contrast appears to the eye Visual Contrast
  31. 31. Visual Contrast — Target L*95 Paper
  32. 32. Visual Contrast Paper (LAB) 95, -0.78, -1.75
  33. 33. • P2P25x has 300 patches • Chart is formatted to be compatible with lots of measurement devices Standard G7 Test Form
  34. 34. • Chromix Curve3 • Tucanna PrintControlPro • Alwan PrintStandardizerX Tools for Generating G7 Correction Curves
  35. 35. • Chromix Verify • Tucanna RapidCheck • Alwan Verify • SpotOn! Verify • EFI ColorVerifier • GMG ProofControl • Bodoni ProofSign Tools for Checking G7 Conformance
  36. 36. AFTER G7 Correction Before G7 Correction
  37. 37. Before G7 Calibration
  38. 38. After G7 Calibration
  39. 39. Gray Balance Compensation
  40. 40. • Relative (native) Black Aim Point instead of targeting absolute reference of (0a*0b*) o Legacy G7 method black aim point is for absolute black reference o Though curves may be smoother you may fail G7 qualification by not being able to hold gray balance in SC • Normalize High Densities o Designed to smooth out drastic curve corrections in the shadows o Again this may make it difficult to pass G7 Qual in shadow areas G7 for the Advanced
  41. 41. • Use ICC profile charts to smooth data o Apply smoothed data to P2P25x G7 for the Advanced
  42. 42. • Do not resize the P2P25x image o Special designed in a dithered pattern for accuracy • Print at least two P2P25x on each test form o Rotate one of the charts 180° o Average data!! Either externally or in the G7 tool o You should have at least two data files to average, more the better! • Consider a program to collect measurements over time o Improves correction curves by statistically more data o Proactive instead of Reactive (uh, what happened?) Tips for Success
  43. 43. (Poll Question) • What is the most troublesome way customers communicate color?
  44. 44. Device Link ICC Profiles Best way to handle color conversion o No trip through LAB o “Baked” color conversion o Fastest since all calculations are done, not only the fly as in a traditional in RIP color conversion o Best method for scaling source to destination Several Device Link generation products are available o They offer features on how to handle scaling o Purity of colors o Black generation preservation
  45. 45. X-Rite i1Profiler v1.5 o Adds Device Link Functionality • Improvement in color gradients not banding as in a traditional LAB conversion • Maintains purity of source black generation to be mapped to the destination instead of converting to 4/C black in LAB conversion Device Link ICC Profiles
  46. 46. Last — Third Webinar • Talk more about device link color matching • Delve deep in how to communicate color intentions throughout production o How to handle customer supplied -- • Proofs from a third-party vendor • Print samples • Named colors – PMS • Brand color matching
  47. 47. • Communicating Color for Grand Format o Input | Reference color spaces o RGB files o New and old school PMS color Upcoming Webinars September 25 2013
  48. 48. Questions and Answers Discuss this topic further: #G7grandformat Type your questions into the side bar on right.
  49. 49. How consistent is your color in printing? G7 for Grand Format Printers X-Rite Color Management for Grand Format Printers