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Today's Topics:
1. Re: Backlight Film Epson 9800 (Walt)
2. RE: U.S. Sheetfed vs. U.S. SWOP (Steve Upton)
3. Re: U.S. Sheetfed vs. U.S. SWOP (Graeme Gill)
4. Re: U.S. Sheetfed vs. U.S. SWOP (Steve Upton)
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Message: 1
Date: Wed, 02 May 2007 15:14:59 -0400
From: Walt <email@hidden>
Subject: Re: Backlight Film Epson 9800
To: email@hidden
Message-ID: <email@hidden>
Content-Type: text/plain; charset=us-ascii; format=flowed;
x-avg-checked=avg-ok-15AD2268
We use the Parrot Color backlit film with the 9800/k3
and are very pleased with the results, but it's possible
that our requirements aren't as demanding as yours.
I think we're using the premium 10 mil.
http://parrotcolor.com/store/home.php?cat=459
Email Carolyn Cope <email@hidden> for
more information.
Good luck!
Walt
From: Igor Perchuk <email@hidden>
Subject: Backlight Film Epson 9800
Hi everyone,
I was wondering if anyone has any experience printing on backlight
film on epson 9800 with K3 inks. I have tried everything and am
getting nowhere. I use to use the epson backlight film before that
worked great, but that was discontinued. Now I have tried the kodak
universal and there reverse backlight film. I am not getting the
contrast I need. The black density is too light and the colors are
washed-out. Is there an alternative media out there that would work
better.
Thanks for any help,
Igor Perchuk
-~
Let us therefore brace ourselves to our duty and so bear
ourselves that if the British Commonwealth and Empire
lasts for a thousand years men will still say, "This
was their finest hour".
Winston Spencer Churchill
June 18, 1940
------------------------------
Message: 2
Date: Wed, 2 May 2007 16:10:31 -0700
From: Steve Upton <email@hidden>
Subject: RE: U.S. Sheetfed vs. U.S. SWOP
To: "ColorSync Users Mailing List" <email@hidden>
Message-ID: <p062408dcc25ec5df873f@[216.254.28.122]>
Content-Type: text/plain; charset="us-ascii"
At 8:21 AM -0400 5/2/07, Mike Eddington wrote:
Thought I goofed so I looked at the profiles again and confirmed
that
I
was looking at US Sheetfed Coated rather than the UnCoated. Yes,
the
profile appears smaller in gamut volume than US SWOP in the
ColorSync
utility using the Yuv view. Any suggestions on how to empirically
evaluate
the gamut of a profile when comparing to another profile?
I was using ColorThink Pro, and also Monaco Gamut Works which both
show
the US sheetfed Coated profile as larger than the US SWOP
profile...but
yeah, I can confirm what you're saying. The Colorsync utility
shows it
as a smaller gamut. After viewing some other profiles of mine, I must
say I'm clueless as to what's going on with how the colorsync utility
displays gamut volume as there's some very strange plots compared to
what ColorThink and GamutWorks come up with. In short, I don't trust
it.
Can anyone offer any insight the differences between the Colorsync
Utility's gamut plots compared with say ColorThink Pro?
yup, I can :-)
The primary difference you are seeing between ColorThink Pro
(CTPro) and the ColorSync Utility (CSU) is that CTPro plots using
absolute colorimetry and the CSU plots using the 'perceptual' intent.
This is when you are looking at the list of profiles and select one
profile to view. If you have opened a single profile into CSU and
select any of the A2Bx intents, then they will be graphed with that
intent...
What this really means:
There are 4 different ways of graphing the device->Lab transform of
a profile:
1. Perceptual - CSU(A2B0 table or select profile in list), CTPro
(option) - you are seeing the gamut of device-values as they are
converted to Lab using the perceptual intent.
2. Relative Colorimetric - CSU(A2B1 table), CTPro(option) - you are
seeing the gamut of device-values as they are converted to Lab
using the rel con intent.
3. Saturation - CSU(A2B2 table), CTPro(option) - you are seeing the
gamut of device-values as they are converted to Lab using the
saturation intent.
4. Absolute Colorimetric - CSU( not available ), CTPro(default) -
you are seeing the gamut of the device as described by the profile.
The white point is lowered to actual paper white and the black
point raised to ink black..
The graphs of 1-3 are of limited use (if any) to the average user
as they describe the 'proofing' behavior of a specific part of the
profile. They do NOT describe the gamut of the device OR the
behavior of the profile when used to OUTPUT an image. It is
interesting to see how rel col raises the black level vs perceptual
and saturation though.
#4 describes the gamut of the device and is a far more useful graph
- and is typically what people expect when graphing a profile.
A good way to confirm this device gamut is to also plot (in
ColorThink) the measurement data that created the profile and
you'll find that the profile conforms to the measurement data
closely - at least on good profiles. This is a good sanity check
for profiles.
The use of the perceptual intent for the default graph in the CSU
is not a good idea - it probably grabs the default intent recorded
in the profile's header, but I'm not sure. The gamut shown (without
explanation) is again, NOT for the device and NOT the gamut
produced when printing. Strictly speaking, it is the gamut that
you'll receive from the profile when using it to convert a CMYK
file to Lab (and on to another profile) using the perceptual
intent; something that is rarely performed in a workflow. Even in
CMYK to CMYK conversions, rel col with BPC is recommended...
Regards,
Steve
______________________________________________________________________
__
o Steve Upton CHROMiX www.chromix.com
o (hueman) 866.CHROMiX
o email@hidden 206.985.6837
o ColorGear ColorThink ColorValet ColorSmarts ProfileCentral
______________________________________________________________________
__
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------------------------------
Message: 3
Date: Thu, 03 May 2007 13:25:23 +1000
From: Graeme Gill <email@hidden>
Subject: Re: U.S. Sheetfed vs. U.S. SWOP
To: email@hidden
Message-ID: <email@hidden>
Content-Type: text/plain; charset=us-ascii; format=flowed
Steve Upton wrote:
4. Absolute Colorimetric - CSU( not available ), CTPro(default) -
you are seeing the gamut of the
device as described by the profile. The white point is lowered to
actual paper white and the
black point raised to ink black..
When you say "raised to ink black..", this worries me. ICC relative
colorimetric
only shifts the devices absolute black point very slightly as a
side effect
of the white point shift when it is encoded into the table. The
relative
colorimetric intent tables should not have had the black point changed
in any other way, unlike the perceptual table, which should have
had its
black point expanded to that of the reference medium black
(0.30911% reflectance).
The use of the perceptual intent for the default graph in the CSU
is not a good idea - it
probably grabs the default intent recorded in the profile's
header, but I'm not sure. The gamut
shown (without explanation) is again, NOT for the device and NOT
the gamut produced when
printing. Strictly speaking, it is the gamut that you'll receive
from the profile when using it
to convert a CMYK file to Lab (and on to another profile) using
the perceptual intent; something
that is rarely performed in a workflow. Even in CMYK to CMYK
conversions, rel col with BPC is
recommended...
The gamut portrayed by the non-colorimetric A2B tables can vary
quite widely. On some
V2 profiles it may be identical to the colormetric table. On
others, it will represent
vendors "secret sauce", and on ICC V4 profiles it is meant to be a
transformation
from the device gamut to the Reference Medium Color Gamut, and
hence should
look pretty the same as the Reference Medium Color Gamut :- so in
my book, noone
should be looking at anything other than the absolute or relative
A2B table
when it comes to examining the gamut of the device. The contents of
all the other tables only give an indication of how the profile
creation software
is manipulating the color.
Graeme Gill.
------------------------------
Message: 4
Date: Thu, 3 May 2007 09:50:24 -0700
From: Steve Upton <email@hidden>
Subject: Re: U.S. Sheetfed vs. U.S. SWOP
To: email@hidden
Message-ID: <p062408e2c25fc235ac57@[216.254.28.122]>
Content-Type: text/plain; charset="us-ascii"
At 1:25 PM +1000 5/3/07, Graeme Gill wrote:
Steve Upton wrote:
4. Absolute Colorimetric - CSU( not available ), CTPro(default) -
you are seeing the gamut of the
device as described by the profile. The white point is lowered to
actual paper white and the
black point raised to ink black..
When you say "raised to ink black..", this worries me. ICC
relative colorimetric
only shifts the devices absolute black point very slightly as a
side effect
of the white point shift when it is encoded into the table. The
relative
colorimetric intent tables should not have had the black point
changed
in any other way, unlike the perceptual table, which should have
had its
black point expanded to that of the reference medium black
(0.30911% reflectance).
right. indeed. I meant it raised it in relation to the perceptual
and saturation intents which pull it down to 0,0,0.
<snip>
in my book, noone
should be looking at anything other than the absolute or relative
A2B table
when it comes to examining the gamut of the device. The contents of
all the other tables only give an indication of how the profile
creation software
is manipulating the color.
exactly! The fact that the CSU displays the perceptual table's
color - with blacks pulled down to 0,0,0 and whites pulled up to
100,0,0 - as a default with no explanation to the inexperienced
user about what it is they are seeing is very misleading. (sorry,
huge sentence). It's not technically incorrect but it certainly
implies colors on output that simple won't be there.
Regards,
Steve
______________________________________________________________________
__
o Steve Upton CHROMiX www.chromix.com
o (hueman) 866.CHROMiX
o email@hidden 206.985.6837
o ColorGear ColorThink ColorValet ColorSmarts ProfileCentral
______________________________________________________________________
__
--
------------------------------
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