Re: Profiling the ip5000
Re: Profiling the ip5000
- Subject: Re: Profiling the ip5000
- From: Dana Rasmussen <email@hidden>
- Date: Mon, 15 May 2006 09:09:55 -0700
- Thread-topic: Profiling the ip5000
> In a message dated 5/14/06 8:52 PM, Dana Rasmussen wrote:
> Hi Dana.
>
> Testchart-generation algorithms, as you call them, have no direct relation
> to the color *gamut* itself of the device being profiled. Other than for the
> mode in which they operate (RGB or CMYK), testcharts are not
> device-specific. They just contain a list of color *numbers* (like for
> example R 35, G 106, B 210, and such) which are sent to the printing device
> through the printer driver, hopefully with no additional color management
> being done on the color values by the driver itself.
I understand this. You are making a assumption, which might be correct,
that those numbers being sent includes enough numbers that are out of the
gamut of a normal CMYK device that what ever software that is generation the
profile can produce a profile that reflects that expanded range.
>
> Let me say it this way: the same color numbers in the testchart produce
> different results on different devices. In devices with a small gamut the
> results have a small gamut; in devices with a larger gamut, the results have
> a larger gamut.
>
> There is one thing having to do with testcharts that may improve the
> profiling procedure, though: it's probably desirable to use testcharts with
> a higher number of patches when profiling devices with a larger gamut, since
> the color range has a wider span, and more sampling points provide a more
> accurate picture of all those intermediate points that would otherwise have
> to be interpolated, i.e., guessed at by the profiling software.
>
> It takes a while to wrap one's head around this aspect of color management,
> but it becomes clearer in time.
>
Yes, I understand this. I have been profiling inkjets, and other devices
like the Fuji Pictrography for a number of years. I do understand gamut
mapping, and color theory in general. In addition, it's been a long time
since college, but my training was in optics, and physics, so I do have a
understanding of color, and light in general, and how it relates to human
vision.
>
> This is what I think is happening: you feel disappointed because the results
> are coming short of your expectations. But perhaps your expectations need to
> be redefined. Or perhaps you are right to expect more, and there is
> something in the way the testchart is being printed that is limiting the
> gamut of the output.
>
> Are you sure that the printer driver is not adding its own color management?
> Or that *your* color management choices are correctly set? (For example, in
> "Print with Preview", leave file untagged and choose "Same as source" in
> Photoshop CS, or "No Color Management" in Photoshop CS2.)
No this is not my issue.
If what I am seeing so far in the profiles I have generated for this
printer, which is admittedly only two so far, is representative, then there
appears to be a very small gain in gamut for a what has to be a large
increase in complexity of both the printer, and the drivers needed to work
with a 12 color device.
I am less interested in theory here, rather to find if others who have had
this device (Andrew? Bruce?) are seeing similar results. What I am seeing
in Monaco Gamutworks is a profile volume of 1,390.900 for the ipf5000,
Ilford Smooth Pearl, compared to a volume of 1,325,388 for the same paper on
the Epson 4800. (And no I don't know what the volume units that Monaco is
using to calculate the volumes are).
I would be happy to send the profiles out to anyone interested to examine
for them selves. Just email me off list.
--
Dana Rasmussen
Seattle, WA
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