Introduction. Achieving Accurate and Consistent Color in Digital Print Production. What is Process Control in Digital Printing?

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1 WHITE PAPER Intelligent Measring Technology when Color Qality conts Achieving Accrate and Consistent Color in Digital Print Prodction A Gide to the Barbieri DOC Process Control Soltion Introdction TABLE OF CONTENTS 1 Introdction 1 What is Process Control in Digital Printing? 2 Challenges in Digital Printing 3 Benefits of Process Control 3 Barbieri DOC Process Control Soltion 4 Reference File and Printing Conditions 4 Barbieri Control Strip 5 Gide to the Barbieri DOC Report 6 Conclsion 6 Abot Barbieri This paper is intended for professionals in the digital printing indstry who reqire a cost effective soltion to achieve accrate and consistent color in wide and large format, flatbed and indstrial printing. We explain process control in digital printing and address the crrent shortcomings with a gide to the Barbieri DOC Process Control Soltion, proving accrate and consistent color is achievable and cost effective. This gide serves to assist yo in determining yor best color management option. What is Process Control in Digital Printing? Process control in digital printing is a series of actions which ensre otpt meets expectation by managing variables which can impact prodction. The main objective is to ensre accrate and consistent color reprodction by creating a tailored a soltion for each printer and media combination. The FOGRA Process Standard Digital 2 (PSD) is an evolving set of gidelines sed to evalate color in digital print prodction. Its three objectives are: THE DIGITAL PRINT INDUSTRY is forecast to grow by 225 percent over the next decade 1. Evolving technologies and applications will frther add to the demands on the digital printing professional. 1 The Ftre of Digital Printing to 2024, Smithers Pira 1. Otpt process control to achieve repeatable reslts. 2. Evalating color fidelity sing a media relative method. 3. PDF/-X compliant workflows. Even with readily available innovations, the shortcomings of crrent practice in process control inclde tedios manal labor, inaccrate gesswork and wasteage de to nseen changes to printing conditions. Using technology sch as the Barbieri DOC Process Control Soltion which incorporates leading edge methods for process control, ensres accrate and consistent reslts for optimal performance and saving costs. 2 FOGRA Process Standard Digital 1

2 Challenges In Digital Printing Digital printing professionals mst ensre colors are accrately reprodced. As technologies evolve and demands change, digital print volmes are increasing and extending into textile, ceramic, glass, laminate and atomotive applications among others. Printers will increasingly need to cater to a range of different media, evolving imaging technologies and inks. Withot a cost effective process control, bsinesses can be impacted by: Prodction downtime. Wasted ink and media. Shipping, application and removal costs. Damaged client relations and reptation. Lost revene and missed opportnities throgh lack of competiveness. On a day to day basis, changes to printer conditions can go ndetected, occring if there is any change to temperatre and hmidity, media and ink. IS YOUR PROCESS CONTROL SAVING YOU MONEY? $ Standard Printing Workflow The workflow for printer configration (fig. 1) involves selecting a printer configration and material combination. Calibration and profiling is then performed. The verification process then analyzes if printing conditions have changed. Measrements are then made on a control strip, generating a qality report and enabling evalation over time and in mltiple locations. SETUP 01 CALIBRATION Throgh ink limit setting and linearization, RIP software analyzes ink application to media, adjsting tonal vales as reqired. PROFILING Data is converted from one device to a selected color space which matches the available colors of another device (printer). Wide format printers have the capability to print close to 900 sqare metres per hor and on expensive sbstrates of p to 5 metres in width. Prodction downtime and wasted resorces can be avoided. Investing in the best available color measrement technology to improve process control boosts prodction and yor bottom line. VERIFICATION Varios factors can remain ndetected and impact prodction. These inclde changes to the printer, ink, media, temperatre and hmidity. With the Barbieri DOC Process Control Soltion, printing conditions can be determined before prodction starts. FIG. 1 Printing workflow REPORT 02 MEASUREMENT Using a calibrated color measring device, patches on a control strip are measred to assess if colors are printing within tolerance. EVALUATION Printing is monitored based on measrement data for prodction over time and in mltiple locations. 2

3 What are the Benefits of Process Control in Digital Printing? Improving process control has a range of benefits in digital print prodction. Assesses print conditions daily, before prodction starts. Eliminates the need to ct large format media (sing a portable device). Processes measrements on the spot (sing a portable device). Enables prodction to be monitored over time and in mltiple locations. Uses a benchmark, or initial reference file, to determine printing conditions. Barbieri DOC Process Control Soltion The Barbieri DOC Process Control Soltion provides an instant pass/fail report, analyzing if printing conditions have changed before prodction starts, saving time, ink and media. It addresses the shortcomings of crrent practice in process control. The Barbieri DOC Process Control Soltion is achieved in three steps: 1. Setp: Create and Save a Reference File Setp is only performed once for every printer/media combination and completed in mintes. After calibration and profiling, a control strip is printed on the selected media. This control strip is measred sing a device with Barbieri DOC 3. A reference file is atomatically created and saved as a preset based on the selected printer/media combination. Alternately, an external absolte reference sch as FOGRA or IDEAlliance can be sed. 2. Daily Check: Print and Measre Control Strip This check is performed daily, before prodction starts. It is based on the saved DOC reference file created dring setp. A control strip is printed on the media. In the device s DOC option, the saved job with the reference file for the printer/media combination is selected. The control strip is measred within mintes for an instant pass/fail reslt. 1. SETUP Print and measre a control strip. This printer/media combination is ato saved as a reference file. 2. DAILY CHECK Select the saved reference and measre the control strip. Daily checks are made at the printer and on media when sing portable device. Use free Barbieri control strip, IDEAlliance, UGRA/FOGRA or cstom wedges. 3. Report: Instant Pass or Fail Reslts Reslts are instantly displayed as pass or fail on the device screen (when sing the SpectroPad) and also saved as a PDF. The generated report shows the printer/media combination, reference sed, tolerance sets and vales. This data can be transferred via wifi or USB to monitor printer performance and qality control. 3. REPORT Reslts shown on device or PDF. 3 The Barbieri SpectroPad (portable), Spectro LFP and Swing inclde DOC fnctionality option. 3

4 The Reference File and Reference Printing Conditions A basic reqirement for color measrement is a reference file. This reference file ses the defined printer/media combination to match measrements made on a control strip. Reference printing conditions se a characterization data set to match CMYK data to the printed otpt. This characterization data set is based on the reqired measrement mode (eg. M0, M1 or M2) and measring conditions sch as illmination (eg. D50), media backing and observation angle (eg. 2 ). Abot the Control Strip Barbieri DOC operates with an indstry compliant, proprietary control strip. It also spports the FOGRA wedge, IDEAlliance and cstom strips. The control strip is a set of patches which meet ISO reqirements 4. The ISO standard recommends a 48 patch minimm, inclding solid process primary and secondary colors, their mid and shadow tones and grays. Barbieri Control Strip Patches and DOC Measrements v PRIMARY COLORS CHROMATIC GRAYS SECONDARY COLORS AUTO POSITIONING LINES PRIMARY MID & SHADOW TONES w WHITE POINT SECONDARY MID & SHADOW TONES IN THE AUTOMATED Barbieri LFP and Swing devices, ato positioning lines indicate placement of the control strip on the measring srface. TOTAL (48 PATCHES) x FIG. 2 Barbieri CMYK Control Strip Tolerances are given in Delta E vales based on these control strip patches: v w x The maximm tolerance vales for primary and secondary colors measre patches A2, A3, A4, A5, A7, A8, A9, A10, A11, B2, B3, B4, B5, B9, B10, B11, C2, C3, C4, C5, C9, C10 and C11. Average grayscale measres B7, C5, C6, C7, D5 and D7. The media is measred on an nprinted white point in patch D6. This action verifies the sbstrate is within tolerance of the media defined in the reference file. The total average and total maximm tolerance measres all patches. 4 Refer to Section 5.1, ISO

5 Gide to the Barbieri DOC Report USING ONLY MAXIMUM OR 95% QUANTILE VALUES The Barbieri DOC report is generated sing evalation software to calclate Delta E (ΔE) vales. These pass/fail reslts are calclated sing tolerance sets which assess the control strip colors and media, giving a reslt based on an acceptable amont of difference to the reference file. Different applications, sch as high qality prints and textiles, have different tolerances. A tolerance set will depend on cstomer expectations and the possibilities of the printer/media combination. Barbieri recommend three tolerance sets, shown in Table 1. Cstom sets can also be sed to sit the prpose of the media and printer capability. Barbieri Tolerance Sets Color Distance Formla ΔE00 T1 Narrow T2 Medim T3 Wide Average Total <2.50 <3.50 <4.50 Maximm Total <6.50 <7.50 <8.50 Primary/Secondary <4.50 <5.50 <6.50 Grayscale < 2.50 <3.50 <4.50 Media < 2.50 <3.50 <4.50 Table 1 Tolerance sets sed to determine pass/fail for DOC Process Control Soltion Data Vales in a Barbieri DOC Report Using only maximm vales incldes otliers, which can impact the interpretation of reslts. A more robst representation of reslts can be obtained by sing the qantile (eg. at 95%), as any otliers are dismissed. The Barbieri DOC Process Control Soltion has the capability to calclate maximm and qantile vales. MEDIA ABSOLUTE (side-by-side) vs MEDIA or SUBSTRATE RELATIVE* 5 FIG. 3 Data displayed on a Barbieri SpectroPad sing the DOC Process Control Soltion ΔE 00 CIE DE 2000 COLOR DISTANCE FORMULA is the most recent calclation and recommended metric. INK measres solid primary and secondary process colors. PRIMARY refers to Cyan, Magenta and Yellow (CMY) channels. SECONDARY refers to Red, Green and Ble (RGB); i.e. CMY combined. GAMUT refers to the match between the device and printed color space. LINEARIZATION is a vital calibration procedre to determine if adjstments are needed for how ink is applied to media. GRAYSCALE is a mixtre of CMY amonts which incrementally achieve ink distribtion linear in appearance. MEDIA measres a blank patch within the control strip to verify the sbstrate remains nchanged in relation to the reference file. ABSOLUTE (side-by-side) EVALUATION refers to matching color based on a reference characterization data set printed on the same media or sbstrate specified. MEDIA or SUBSTRATE RELATIVE EVALUATION is individal image appraisal of color appearance sed if white points differ de to two different sbstrates. *5 Media relative, the term sed by FOGRA, is an increasingly favored method for evalation. IDEAlliance refer to this evalation method as sbstrate relative. The Barbieri DOC Process Control Soltion has the capability to measre media relative and absolte. 5

6 Conclsion Digital wide and large format, flatbed and indstrial printing professionals reqire a cost effective process control soltion to achieve accrate and consistent color. This is especially important given the crrent and forecast growth of the digitial printing indstry. As innovations and prodction techniqes evolve, the gidelines for process control for digital printing also evolve. Otdated practices and limited technologies impact prodction and revene by casing printer downtime and wasteage. Unseen factors necessarily impact prodction. The Barbieri DOC Process Control Soltion is cost effective and easy to se. It offers flexibility with media types and evalation methods, cstomization and instant reslts. It was devised to address the shortcomings of crrent practice in process control based on client experience, innovations from international indstry bodies and internal research and development. A process control soltion which is cost effective and delivers optimal prodction is possible with the Barbieri DOC Process Control Soltion. Barbieri DOC Process Control Indstry compliant and versatile se proprietary or preferred control strip. Determine on the spot if colors are printing accrately (when sing portable device). Monitor printer performance over time and prodction in mltiple locations. Avoid wasted resorces from changes to ink, media, temperatre, hmidity and after printer maintenance. Generate an instant PDF report, transfer via USB, wifi or view reslts on device. Easy to se for reslts within mintes. Available with these Barbieri spectrophotometers SpectroPad Spectro LFP Spectro Swing Abot Barbieri Barbieri is an internationally operating manfactrer and spplier of intelligent color measrement systems which ensre the highest image qality for professional digital printing. The international Barbieri technical laboratory continosly discovers new featres, characteristics and applications to improve prodcts and assist clients for improved performance. Barbieri is the color measrement market leader for wide and large format, flatbed and indstrial printing. How can yo achieve accrate and consistent color reprodction with yor process control? Upgrade a Barbieri device with the Barbieri DOC Process Control Soltion or select DOC as a featre with any new Barbieri SpectroPad, Spectro LFP or Spectro Swing. This white paper was written by Tanja Polegbic dring an internship with Barbieri Electronic as a research component to the Master in Color Design & Technology (1 edition) from the Politecnico di Milano, Italy. Barbieri electronic snc/ohg Via I.-Seidner-Str Bressanone/Brixen - Italy Tel Fax info@barbierielectronic.com 6