# Printer Ink Limit Optimization

```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
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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
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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%
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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
\
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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?
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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
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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
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What is the acceptable
ink/toner limit?
Recommendation: No lower than 230% to minimize apparent color errors
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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
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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
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Questions?
```