Epson Printers and Black Generation
Epson Printers and Black Generation
- Subject: Epson Printers and Black Generation
- From: Darrin Southern <email@hidden>
- Date: Mon, 12 Feb 2001 17:58:00 +1100
Dear List,
I have been working on an issue regarding the CYMK printing to the Epson
7000, 7500, 9000 + 9500 printers and the role the black generation places
with profiles built and applied to the BEST Color Rip.
I have put a scan of a baseline test printed from the BEST to the Epson 7000
on my homepage at
http://homepage.mac.com/darrinsouthern/ the two files are
80k and 140k, (this was the smallest without loosing quality).
This test was printed without any 'paper' or 'reference' profiles. It was
printed with the BEST rip set to 720 dpi (1440 dpi gave the same sort of
result)
The Epson 7000 has the light magenta and light cyan to build the lighter
colors, and the yellow ink does not show up the dot pattern (stiple).
The Epson 9500 prints the baseline target the same way.
The problem is the black, which seems to print a very large dot for the
lighter shades. This becomes an issue when lighter colors are needed to be
proofed, and this output I have mentioned before on the digest as the 'dodgy
black stiple'.
I have then built a paper profile without a reference profile, and then
printed any test file with the 'BESTref5' profile as the reference profile.
I printed the 'QualityofColors' file and set the total ink to 180%.
When printing the test patches for the ColorBlind profiles, I used the 1440
patches, which the 'dodgy black stiple' appeared on a particular range of
patches. With PrintOpen 4.0 Mac, there are only 840 patches, which limits
these 'dodgy black stiple' patches.
I have adjusted the Black Weight and Black Start within ColorBlind
Professional 3.6, and this only seemed to reduce the Black Generation, not
remove it. The settings removed it from the area of the image that has
values of C:39 M:66 Y:95 K:11 but I was unable to remove it from the area of
the image with the values of C:72 M:58 Y:67 K:29
Within PrintOpen 3.0.1 and 4.0, there is ability to build a profile and with
the Black Length set to 0 'Skeleton' and setting the Width to 0 'Neutrals'
gets me a little better result than with ColorBlind, but I need to build a
profile with 'No Black' in the Color Composition to completely remove any
trace of black in the colors.
I have not made any real changes to the Minimum dot and the Catchlight in
the Modify process colors, as this will 'probably' adjust the appearance of
the output.
I do not believe this 'dodgy black stiple' is a total ink issue, as building
color squares in Illustrator with the yellow values moving from 10%, 30%,
55%, 80%, 94% and 100%, all with a 10% black, and then printing them out
with the different profiles, gives the same results.
The PrintOpen 'Skeleton' profile gives a slightly better result than the
ColorBlind 'Black Start' profile, but only when the PrintOpen 'No Black'
profile is used, does the stiple get removed.
I hope that this is not the only benefit of PrintOpen 4.0 (Black Generation
is a feature of the upgrade mentioned at their website), as I needed to scan
my targets in PO 3.0.1 and then import then into PO 4.0, as I get errors
working with the DTP41. I have checked the motor speed of the DTP41 and it
is set to 1.2, and the device works fine with the 30 targets in PO 3.0.1
The PrintOpen 'No Black' profile does not just remove the black from the
squares, but it uses a mix of C M with the existing Y to 'darken' the square
to give the appearance of the 10% black.
I apologies for the long post, but I wanted to get all the information out
to the list, even to just guide anyone else just starting out.
Should I be using another profiling software ? Or profiling in RGB ?
Should I be happy with the output produced by removing the black from the
images ?
Darrin Southern.