Following standards ('Generic CMYK Profile' analysis)
Following standards ('Generic CMYK Profile' analysis)
- Subject: Following standards ('Generic CMYK Profile' analysis)
- From: Henrik Holmegaard <email@hidden>
- Date: Sat, 8 Dec 2001 17:04:15 +0100
John Zimmerer <email@hidden> wrote:
The Default profiles that ship with ColorSync are meant to be
default INPUT, not OUTPUT, profiles.
The way a problem is posed may shape the actions taken. This is the
reason I asked for this thread. Thinking of the 'Generic CMYK
Profile' as source for LEGACY data makes it an unimportant profile, a
profile which is of little consequence. And this is a misconception,
as the flywheel ABC of a profile chain is meant to illustrate.
The first post I wrote to the List described how to use LOGO ColorLab
to check the color consistency across a monitor, and the MeasureTool
is still a very handy tool. It's counterpart is CHROMiX ColorThink
which tells me what's inside the profile to which I trust my output.
'Generic CMYK Profile' is 40 Kb; the Lab to CMYK direction has 17
grid points and 8 bit; the CMYK to Lab direction has 6 grid points
and 8 bit ... the same as in ICM1 BTW; the paper white is L 100 a 0 b
0 and the maximum black is L 0 a 0 b 0. There is no precision in this
profile, and where is the gamut mapping?
If I look at a soft proof of an RGB / Lab image, then I see banding
in gradients, and in CMY plus K plate view the image is made up of an
unbelievable amount of black. The black plate indicates an unstable,
toner-based color printer where such massive black saves on costly
CMY and cloaks CMY variations through the day.
This is consistent with the LaserWriter driver, which I believe
defaults to 'Generic CMYK Profile' for QuickDraw output. And the
PostScript color printer that comes to mind as a natural match for
the 'Generic CMYK Profile' color space is the Apple Color
LaserWriter. While QuickDraw does not accept any color model other
than RGB, it does not follow that 'Generic CMYK Profile' is absent as
OUTPUT profile in the Mac OS : The Color LaserWriter.
We will consider your comments for the future.
The future was at the latest when Adobe put the first application out
that used the ColorSync Workflow feature.
In the world of color management software, a simple test of the
default output printing condition a company's software installs is
whether that company would distribute 50,000 copies of a four color
offset brochure using its own defaults.
Adobe product management could with equanimity accept, because Adobe
installs standards-based CMYK output profiles. But could Apple
product management do this, too? Considering the user means taking
the user seriously, because a company lives by its users. That's why
defaults are not inconsequential.
Phil Green is right in the following from Vol 1 No 481, as is Tony
Johnson who helped me put together a first UK feature about ICC
workflows back in 98, and Dr. Dolezalek at FOGRA when they all say
it's nonsense to talk about fingerprinting presses as presses of
different make and model can produce the same color if run right.
What I should have reported in the early List thread is that within
the ECI there are two factions, as it were. Those who argue that
better quality can be achieved with a custom profile. These are the
people whose customers are car manufacturers and critical magazine
publishers. And the other faction which takes the practical view that
if it's standard, then it's up to the press operator to bring the
press up to the necessary color behaviour.
Date: Sun, 07 Mar 1999 12:11:01 +0000
From: Phil Green <email@hidden>
Subject: Re: Of color and Keynes
Henrik Holmegaard wrote:
And reference printing conditions are OK only if you don't know where the
job will output. Otherwise go for the actual press if you possibly can.
As a former press operator, I think you're overstating the need for
custom press profiles. Printers need to be able move jobs from one press
to another to level loads, so 'fingerprinting' each press is of limited
use.
It makes more sense to define characteristic printing conditions that
are based on what is achieved by printers today. Any decent press
operator can adjust ink rheology and press performance to hit a
(well-chosen) standard for a given substrate - if they can't, they are
unlikely to be able to achieve repeatability of the conditions in which
the press was profiled.
You then set up proofing systems to simulate as well as possible the
standard printing characteristic (not the other way around).
Initatives by the standards community, like ISO 12647 for process
control and the reference printing conditions concept, mean that you
don't need to know whether the press is in Hong Kong or parked around
the corner. Custom profiles are then only needed when it necessary to
define a departure from the baseline.
Phil Green