Re: Real world experience w/ GMG and Oris RIPs
Re: Real world experience w/ GMG and Oris RIPs
- Subject: Re: Real world experience w/ GMG and Oris RIPs
- From: "Mike Eddington" <email@hidden>
- Date: Tue, 23 Nov 2004 12:45:59 -0500
- Importance: Normal
Title: Message
<are you sure the
process lowers the delta E of the
overall profile, or only of the particular
test values that are being
used, while errors in colors that lie between
those test values remain
the same, or even get worse
?>
After looking into
this further I can verify that colors in between patches are not left out. GMG
does allow one to view the curves that exist between fulcrums. If one
fulcrum is adjusted and the dE gets pulled down, the interpolation curve between
the fulcrums will be changed too. Therefore colors between the test values are
indeed adjusted, whether or not this is adds to profile accuracy is
subjective.
My results using GMG
in both a proprietary and ICC workflow show much better numerical and visual
results for the iterative method. Here are the results comparing the iterative
approach GMG implements vs the single measurement cycle in creating an ICC
profile, both created with the IT8 7/3. Upon profile completion,
an IT8 was output and measured in Gretag MeasureTool.
GMG proprietary
proof compared to TR001 data:
Ave dE: 1.09,
max dE: 4.89
GMG ICC proof
compared to TR001
Ave dE: 4.10, max dE
13.79
I should also point
out that upon the 1st measurement cycle of the proprietary method, the average
dE started out at 2.35 with a max of 7.32. These would represent a non-iterative
profile, and are still better than the ICC results.
Again, whether any
of this makes a difference in overall proof quality would be subjective...i.e.
if you don't trust the numbers, you'll have to rely on a visual check. Looking
at sample proofs I output, the GMG iterative proof is
visually closer to the target proof than the ICC proof. I also see visual improvement from a proof from
the 1st iteration to the last. The ICC proof doesn't look horrid, but
it doesn't look as close visually. Perhaps it is due to the 4D tables of
GMG vs the 3D tables of an ICC profile...but I can't argue whether or not there is "a
scientific basis to explain why an iterative approach provides any
benefit", all I can say is that I see better results using
it.
Also, in regards to Terry's observation that around 200
patches are not measured from the ECI 2002 chart. the explanation I got from GMG
is below...in slightly broken english
;-)
"on the eci
chart there are some patches twice---- we only measure them
once.
also we always need all possible overprint
combinations to form this 4d color matrix which makes our profiles so
accorate. example 3% cyan is on the cart but 3/3/3 patch is
not available, therefore we have to skip the 3% patch too. if you want
this is a limitation in the way our profiles are defined. Well but this
limitation also makes us so accorate.... so you judge :-)"
mike
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