Prediction of inkjet printing quality using i.jetset device. Christophe TREHOULT

Transcription

1 Prediction of inkjet printing quality using i.jetset device Christophe TREHOULT

2 A part of the digital printing research program of CTP ( ) To develop a complete system to evaluate ink jet printing quality by IA in correlation with visual ranking 2

3 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

4 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

5 Set of papers Plain papers Multifonctional Enhanced for Inkjet Coated Matt Glossy Sources Printer manufacturer Paper maker Available on the market In development 5

6 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

7 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

8 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

9 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

10 Printing quality criteria Print through Unevenness Vignettes 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

11 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 Good Bad Good 0 11

12 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 K Text sharpness Optical Density Colorimetry Line sharpness Contrast Bleeding K/Y Bleeding M/Y Sample. Ref. Measurements Human Evaluation scales 12

13 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

14 Printing test form by C.T.P. Print through Line sharpness Vignettes Colorimetry Optical density Bleeding Text sharpness Line sharpness Bleeding Uneveness 14

15 Scanning Professional scanner 3000x3000 dpi. 48 bits color depth. Implementation of a script in the Twain driver. Reproducibility > 95% 15

16 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

17 View from the main application form Single analysis Complete automation of full process Quicken processing 17

18 Subjective assesment Bleeding Measured index 5.0 R 2 = Human evaluation 18

19 Subjective assessment Line sharpness Measured index R 2 = Human evaluation 19

20 Subjective assessment Text quality Measured index R 2 = Human evaluation 20

21 Subjective assesment Print through Measured index R 2 = Human evaluation 21

22 Subjective assesment Unevenness Measured index R 2 = Human evaluation 22

23 Subjective assessment Vignettes continuity Unevenness 250 Light level Grey level profile analysis Integration area Amplitude factor Experimental curve Theoretical curve Dark level

24 Vignettes continuity Measured index 5.0 R 2 = Human evaluation

25 Contrast Grey level profile analysis

26 Contrast - details Max grey level difference Theoretical curve Experimental curve Grey level variation Period variation thickening 26

27 Dot shapes scanning Scanner maximum magnification on original print dots Clustering print dots 27

28 Stereomicrospope print dots Image acquiring 70µm 70µm 28

29 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

30 Gamut evaluation Gamut curve integrated to get one measurement index 30

31 Colorimetry ( Gamut ) Gamut Gamut HP815c paper 05-A1 HP8250 paper 05-A1 Larger gamut = Better possibility for color reproduction Ink amount linked to gamut area 31

32 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 N sur J M sur J C sur J 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 DOUAI CEDEX - Tél: (33) FAX (33) Siège social : Domaine Universitaire - BP Grenoble cedex 9 - France tél. (33) télécopie (33) Centre Technique de l'industrie des papiers, Cartons et Celluloses - loi du siret code APE 731 Z Standard mode 32

33 Result synthesis form Results file 1/2 Date: 07/09/07 Paper: a 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 Colorimetry Contrast Bleeding N/J Bleeding M/J Line sharpness K Text C 1.86 Blank Black Gain Gloss M 1.94 Uneveness " 60" Ink setting Print through 2.48 Vignettes Mean Image human evaluation Date: 07/09/07 Paper: a Source: Type: Gram m age: Soft V : 2.0 Scanner: Epson V700 Results file 2/2 Gamut Printing mode Gamut measure : EyeOne Test form: FTJE8V Optical density Vignettes 5 4 Colorimetry Print through 3 Contrast Uneveness 0 Bleeding N/J Text M Bleeding M/J -100 Text C Line sharpness Text K 33

34 Analysis delay for one printer Printing Scannerisation Images treatments 2 to 5 min 5 min 5 min Total 12 to 15 min 34

35 Automated analysis delay Interleaved treatments Delay (Min) Sample 1 5 Printing Samp Scan Print. Samp Treat Scan. Print. Samp Treat. Scan. Print. Samp Treat. Scan. Print Treat. Scan Treat Min (First sample) + (n-1) x 5 Min 35

36 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

37 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

38 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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