Printer Ink Limit Optimization How can a limit for ink saving be determined that does not affect print quality Yue Qiao, Larry Ernst December 13, 2012 Problem Definition How low is the ink limit too low to have an acceptable color quality? Customers would like to reduce ink/toner usage with minimum loss of color quality Manufacturers would like to boost ink usage Printers normally have a ink limit below 300% – Dryer or ink, other mechanical, paper problems – Customers way of reducing ink coverage on a page ICC disucssion 2 Ricoh Ink/toner Optimization Technology There could exist multiple sets of printer CMYK values that produce the same/similar CIELab color Ricoh technology: – Creating an accurate color conversion model – Conducting a search algorithm to find many possible CMYK combinations – Choosing the CMYK value to satisfy the requirement ICC disucssion 3 Ricoh Ink/toner Optimization Technology For CMY=[55 40 55 0], total150% coverage •10 sets of CMYK values have the same appearance •Minimum ink coverage is [35 0 33 37] total 115% •Ink saving 45% For CMY=[70 100 100], total 270% coverage •13 sets of CMYK values have the same appearance •Minimum ink coverage is [3 7 0 74] total 84% •Ink saving 186% ICC disucssion 4 Printer color conversion with an ink limit Device path C’M’Y’K’ CMYK fFormula IICC with ink limit RGB C’M’Y’K’ \ \ I C C FFormula CMYK \ ICC disucssion 5 Ink/toner Optimization for Printers with Ink/toner Limit Can the technology maximize the color capability for a printer with ink/toner limit? With the help of the technology, what’s the minimum ink limit is acceptable for an acceptable print quality? ICC disucssion 6 Experiments RPPS ink/toner optimization technology was experimented on three printers: – Production cut sheet EP printer – Production continuous form inkjet printer – High end desktop inkjet printer Create CMYK to Lab conversion table 17^4 – Calculate % of CMYK values that exceed the ink limit. E.g., 60% colors above 160% ink limit – Apply Ink optimization method to the colors over the ink limit – Replace the original CMYK value above the ink limit with reduced C’M’Y’K’ that below the ink limit – Calculate % of CMYK values that exceed/not exceed the ink limit ICC disucssion 7 Experiment Results 100 120 90 100 80 70 80 60 60 loss% 50 loss% acuracy% 40 acuracy% 40 30 20 20 10 0 0 150 200 Cutsheet EP 250 150 300 120 200 100 250 300 Continuous form inkjet 80 loss% 60 acuracy% 40 20 0 150 200 250 300 Desktop inkjet ICC disucssion 8 What is the acceptable ink/toner limit? Recommendation: No lower than 230% to minimize apparent color errors ICC disucssion 9 On going experiments Relationship between ink limit and color quality How does gamut ratio VinkLimit/V0 relate to color quality? Where V0 is the gamut volume of 400% ink coverage, and VinkLimit is the gamut volume of the ink coverage at the ink limit. Predicting that the gamut volume ratio is the key parameter for determining the ink limit with an acceptable color quality ICC disucssion 10 What would we like ICC to help Get feedback on our study Other members share their knowledge and study Possible white paper on printer ink limit recommendation ICC disucssion 11 Questions?