Prediction of inkjet printing quality using i.jetset device Christophe TREHOULT
A part of the digital printing research program of CTP (2002-2004) To develop a complete system to evaluate ink jet printing quality by IA in correlation with visual ranking 2
Why? None existing standard system to measure Ink-Jet printing quality Growing demand of industrial partners. On line measurement for process control. Research & development of new coating. BENCHMARKING 3
Aims Print quality assessment using visual scales Transfer the know-how of the CTP expert team into a machine Sensitivity Reproducibility Automatisation Full & efficient system Ink jet and other processes To be able to give one global measurement of printing quality for each sample. 4
Set of papers Plain papers Multifonctional Enhanced for Inkjet Coated Matt Glossy Sources Printer manufacturer Paper maker Available on the market In development 5
Categories of printers Several generations of printers from 1999 to 2006 Several purposes Report editing Photo reproduction Multifonctional machines Different manufacturers Main competitors in this field 10% 15% 10% 40% HP EPSON CANON LEXMARK AUTRES 25% Source Distributique 2005 6
Set of printers HP Deskjet 815c, Deskjet 5850, Photosmart HP8250 Epson Stylus color 740, Stylus C70, Stylus Photo 890, Stylus C84, Stylus D88, Stylus Pro 4000 (Wide format) Canon BJC 6000, i865, Pixma ip4200 Lexmark (Z45) Pigments/ dyes based inks Piezo and thermal technologies 7
Print quality & human evaluation Human scales - Print quality expert team since 1999 CTP Others (Paper makers, suppliers, printers..) Print quality index (for each measure) Human evaluation scales Bleeding Print unevenness Print trough Ink spreading Text sharpness Vignettes 0 = Very good 5 = Very bad 8
Summary of measures Optical density (Black) Gamut Colorimetry Contrast (Black) Bleeding Black / Yellow Magenta / Yellow Line sharpness (Black) Text sharpness Black Magenta / Cyan Unevenness (Blue) Print through Vignettes 9
Printing quality criteria Print through Unevenness Vignettes 5 4 3 2 1 0 Optical Density Colorimetry Contrast Bleeding K/Y M Text sharpness Bleeding M/Y 0 : Good / 5 : Bad K Text sharpness Line sharpness Sample. Ref. 10
C.T.P. printing quality index Each printing quality criteria converted into index 0 = Very good Bad 5 5 = Very bad 4 Bad 2 = Acceptability level Bad 5 Index 3 2 1 Good Bad Good 0 11
CTP s image analysis workflow Specific Ink jet test form Set of Ink jet printers Image Acquisition Scanner & opt. Fitting image analysis treatments Report & Global quality Index Comparison With CTP s Data base Print through Unevenness M Text sharpness 0 : Good / 5 : Bad Vignettes 5 4 3 2 1 0 K Text sharpness Optical Density Colorimetry Line sharpness Contrast Bleeding K/Y Bleeding M/Y Sample. Ref. Measurements Human Evaluation scales 12
Developments Gradation scales for each printing quality criterion Test form Printing parameters for each printer. Images acquisition & treatments. Correlation between evaluation scales & image analysis treatments Ready for the future evolution Adaptated to the needs of the final user 13
Printing test form by C.T.P. Print through Line sharpness Vignettes Colorimetry Optical density Bleeding Text sharpness Line sharpness Bleeding Uneveness 14
Scanning Professional scanner 3000x3000 dpi. 48 bits color depth. Implementation of a script in the Twain driver. Reproducibility > 95% 15
Software Choice : Visilog 6.5 (NOESIS) - RunTime Version Integrated system Driving of all the devices trough a stand alone application Acquisition & archiving images Interactive Measure Treatment Calibration 16
View from the main application form Single analysis Complete automation of full process Quicken processing 17
Subjective assesment Bleeding Measured index 5.0 R 2 = 0.97 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 Human evaluation 18
Subjective assessment Line sharpness Measured index 5.0 4.5 4.0 3.5 R 2 = 0.96 3.0 2.5 2.0 1.5 1.0 0.5 0.0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 Human evaluation 19
Subjective assessment Text quality Measured index 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 R 2 = 0.98 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 Human evaluation 20
Subjective assesment Print through Measured index 5.0 4.5 R 2 = 0.95 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 Human evaluation 21
Subjective assesment Unevenness Measured index 5.0 4.5 4.0 3.5 R 2 = 0.96 3.0 2.5 2.0 1.5 1.0 0.5 0.0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 Human evaluation 22
Subjective assessment Vignettes continuity Unevenness 250 Light level Grey level profile analysis 200 0 2000 150 Integration area 100 50 0 Amplitude factor Experimental curve Theoretical curve Dark level 0 200 400 600 800 1000 1200 1400 1600 1800 2000 23
Vignettes continuity Measured index 5.0 R 2 = 0.94 4.0 3.0 2.0 1.0 Human evaluation 0.0 0.0 1.0 2.0 3.0 4.0 5.0 24
Contrast Grey level profile analysis 250 200 150 100 50 0 25
Contrast - details Max grey level difference Theoretical curve Experimental curve Grey level variation Period variation thickening 26
Dot shapes scanning Scanner maximum magnification on original print dots Clustering print dots 27
Stereomicrospope print dots Image acquiring 70µm 70µm 28
Color measurement Connected and interfaced in the software Spectroscan Spectrolino Eye-one (USB connected) Black O.D. and gradation curve values translated into measurement indexes (0 to 5) 29
Gamut evaluation Gamut curve integrated to get one measurement index 30
Colorimetry ( Gamut ) Gamut Gamut 100 100 80 80 60 60 40 40 20 20 0-100 -80-60 -40-20 0 20 40 60 80 100-20 0-100 -80-60 -40-20 0 20 40 60 80 100-20 -40-40 -60-60 -80-80 -100-100 HP815c paper 05-A1 HP8250 paper 05-A1 Larger gamut = Better possibility for color reproduction Ink amount linked to gamut area 31
Images evaluation Ribbon Alien SOHO PAGE TEST POUR IMPRESSION J.E. Parts de Marché des Imprimantes: AUTRES Imprimantes Pourcentage du marché 20% 40% H.P. H.P. 40 EPSON 25 CANON 15% CANON 15 AUTRES + LEX 20 25% EPSON Comparatif des papiers Non Couchés sur les 3 Machines: 4.0 Figure 2a: Evaluation du bleeding Papiers NC, sur H.P. 3.5 3.0 2.5 2.0 1.5 1.0 N sur J M sur J C sur J 0.5 0.0 A1 A2 D1 D2 D3 D4 D5 D6 D7 D8 D9 Réf ér ences papier s Low Res. High Res. Antenne CTP - 59, rue Jean Perrin - ZI DORIGNIES - 59508 DOUAI CEDEX - Tél: (33) 03.27.98.05.51 - FAX (33) 03.27.98.05.49 Siège social : Domaine Universitaire - BP 251-38044 Grenoble cedex 9 - France tél. (33) 04 76 15 40 15 - télécopie (33) 04 76 15 40 16 Centre Technique de l'industrie des papiers, Cartons et Celluloses - loi du 22.7.48 - siret 775594.815.00018 - code APE 731 Z Standard mode 32
Result synthesis form Results file 1/2 Date: 07/09/07 Paper: 070215-05a Printing mode Source: HP 8250 Type: Grammage: Soft V : 2.0 Scanner: Epson V700 Test form: FTJE8V 13 Criteria Index L a b Delta E Optical density 3.37 87 3 70 21.7 Colorimetry 2.0 54 50 18 42.9 Contrast 2.16 51 62-19 13.1 Bleeding N/J 2.27 44 3-47 10.8 Bleeding M/J 1.74 63-28 -46 32.2 Line sharpness 2.09 62-42 24 26.8 K 1.73 87 3 70 Text C 1.86 Blank Black Gain Gloss M 1.94 Uneveness 2.40 5" 60" Ink setting Print through 2.48 Vignettes Mean 3.20 2.3 Image human evaluation Date: 07/09/07 Paper: 070215-05a Source: Type: Gram m age: Soft V : 2.0 Scanner: Epson V700 Results file 2/2 Gamut 70 70 53 0 65 1726 39 53 65-1 32 1039 100 65 65 48 0 61 1442 31 48 54-1 27 724 72 54 49 0 54 1308 80 65 49 70 0 43 1524 7764 60 40 Printing mode Gamut measure : EyeOne Test form: FTJE8V 13 20 Optical density Vignettes 5 4 Colorimetry 0-100 -80-60 -40-20 0 20 40 60 80 100 Print through 3 Contrast -20 2 1-40 Uneveness 0 Bleeding N/J -60-80 Text M Bleeding M/J -100 Text C Line sharpness Text K 33
Analysis delay for one printer Printing Scannerisation Images treatments 2 to 5 min 5 min 5 min Total 12 to 15 min 34
Automated analysis delay Interleaved treatments Delay (Min) Sample 1 5 Printing Samp. 2 10 Scan Print. Samp. 3 15 Treat Scan. Print. Samp. 4 20 15 Treat. Scan. Print. Samp. 5 25 15 Treat. Scan. Print. 30 15 Treat. Scan. 35 15 Treat. 35 15 15 Min (First sample) + (n-1) x 5 Min 35
Follow-up of the system Printers & Medias evolution Technology. Resolution. Inks characteristics. Digital printing survey at C.T.P. Updates Calibration & control Training courses 36
Measures to be added Cockling of samples Evaluation of ink setting Evaluation of wallace test Evaluation of rub test Evaluation of water fastness Evaluation of light fastness Others processes Xerography Large format ink jet Flexo, Rotogravure. 37
Conclusion New technology for fast and reliable assessment of ink jet quality Ready to be adapted to the future evolution Visual assessment connected to image analysis Usefull for bench-marking, research and process control 38
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