Implemen'ng a G7 Calibrated Workflow for Gravure Package Prin'ng Jing Sheng and Bob Chung! RIT School of Media Sciences! Presented at the RIT Gravure Day, April 10, 2013!
2 Introduc*on Prin*ng is a form of manufacturing. Aims and tolerances Calibra*on Produc*on varia*on Prin*ng technology advancement File format From applica*on- specific to PDF/X Press calibra*on Based on TVI, neutrality, data set Prin*ng process control
G7 Defines Press Calibra*on Aims 3 G7 is a neutrality- based press calibra*on method. Star*ng from a set of pre- determined CMY triplets Recognizing paper color, black solid, and CMY solids of any CMYK imaging device as input Using graph paper to determine tone reproduc*on aims and gray reproduc*on aims. CGATS TR 015 a descrip*on of a mathema*cal procedure to establish colorimetric aims for the 3- color neutral scale and the black scale.
4 IDEAlliance s G7 Pass/Fail Criteria Using 23 triplets, weighted average and maximum L* = Abs (L* sample L* target ) C h = ((a* sample a* target ) 2 + (b* sample b* target ) 2 )) 0.5 Weighted L* = L* x (1- max( 0, (%- 50)/50 x 0.75 )) Weighted Ch = C h x (1- max( 0, (%- 50)/50 x 0.75 )) Tolerances for average weighted L* and C h = 1.5 Tolerances for maximum weighted L* and C h = 3.0
5 G7 Master Printer Qualifica*on A G7 consultant is engaged in the G7 qualifica*on process by Working with the printer to implement the neutrality- based press calibra*on Submifng printed sheets and proofs for comformity assessment
6 G7 Cer*fied GRACoL Printer RIT s PSA (Prin*ng Standards Audit) is the next level of G7 that focuses on dataset conformance. IDEAlliance awards GRACoL Cer*fied Printer based on the PSA cer*fica*on and G7 Master Printer status.
7 Objec*ve Implemen*ng a G7- calibrated workflow for gravure prin*ng at a package prin*ng company. G7 press calibra*on procedure 1) Organize a press run, including test form design. 2) Engrave and print one- half of the cylinder (Run_1). 3) Measure press sheet and generate G7 curves. 4) Engrave with the adjusted test form on the other half of the cylinder and print (Run_2). 5) Verify repeatability and G7 conformance.
1. Press Run Organizer 8 Test form design Specify press, inks, and paper/substrate Prin*ng aims Color measurement G7 s/w
1. Press Run Organizer 9 An example of a test form Key target is the 25- step P2P target.
10 2. Engrave and Print (Run_1) Engrave according to the current engraving standards Print to conform to prin*ng aims (Run_1)
11 3. Measure & Generate G7 Curves Measure P2P targets with a scanning spectrophotometer, e.g., X- Rite i1 IO. Enter measurement data into Curve2 s/w. Implements the G7 adjustment curves in Photoshop. X- Rite i1 IO & i1 Pro 2
12 3. Measure & Generate G7 Curves Curve2 example of Run_1 spider and TVI plots The spider plot verifies solid ink conformity. The TVI plot reflects the dot gain of each ink color. Run 1 spider plots Run 1 TVI
4. Engrave and Print (Run_2) 13 By engraving to the same cylinder and prin*ng to the same aims, we can verify the repeatability of the Run_1, and verify G7 conformity in Run_2.
14 4. Engrave and Print (Run_2) Curve2 examples of Run_2 spider and TVI plots The spder plot verifies the solid color repeatability. The TVI plot reflects the effect of curve adjustment. Run_2 spider plots Run_2 TVI
5a. Verify Run- to- Run Repeatability 15 Curve2 example showing mul*ple measurement files can be averaged.
16 5b. Verify Run_1 & Run_2 Neutrality Curve2 examples Run 1 Grey Balance Run 2 Grey Balance
17 Paths Forward Seek a gravure packacking printer interested in the G7 press calibra*on. Create a co- op or intership for a qualified RIT student to help implement the G7. Further improvement includes G7 curves are implemented in Photoshop and no change is applied to the default engraving (no impact to the current workflow). Once proven, G7 curves can be implemented in the engraving opera*on.
18 Expected Outcome and Benefits The company - - - apply G7 Master Printer status The RIT student - - - apply knowledge/gain real experiences RIT Professor - - - serve industry & educa*on while gaining publishing opportunity
19 Thank you. Q/A